Merge branch master into package-grpc-tools-doc

.bazelrc

@@ -0,0 +1,3 @@
+# load bazelrc from the legacy location
+# as recommended in https://github.com/bazelbuild/bazel/issues/6319
+import %workspace%/tools/bazel.rc

.clang_complete

@@ -14,4 +14,5 @@
 -Ithird_party/cares
 -Ithird_party/googletest/googletest/include
 -Ithird_party/googletest/googlemock/include
+-Ithird_party/nanopb
 

BUILD

@@ -131,7 +131,6 @@ GRPCXX_SRCS = [
     "src/cpp/server/create_default_thread_pool.cc",
     "src/cpp/server/dynamic_thread_pool.cc",
     "src/cpp/server/health/default_health_check_service.cc",
-    "src/cpp/server/health/health.pb.c",
     "src/cpp/server/health/health_check_service.cc",
     "src/cpp/server/health/health_check_service_server_builder_option.cc",
     "src/cpp/server/server_builder.cc",
@@ -151,7 +150,6 @@ GRPCXX_HDRS = [
     "src/cpp/common/channel_filter.h",
     "src/cpp/server/dynamic_thread_pool.h",
     "src/cpp/server/health/default_health_check_service.h",
-    "src/cpp/server/health/health.pb.h",
     "src/cpp/server/thread_pool_interface.h",
     "src/cpp/thread_manager/thread_manager.h",
 ]
@@ -247,6 +245,7 @@ GRPCXX_PUBLIC_HDRS = [
     "include/grpcpp/support/config.h",
     "include/grpcpp/support/proto_buffer_reader.h",
     "include/grpcpp/support/proto_buffer_writer.h",
+    "include/grpcpp/support/server_callback.h",
     "include/grpcpp/support/slice.h",
     "include/grpcpp/support/status.h",
     "include/grpcpp/support/status_code_enum.h",
@@ -279,6 +278,7 @@ grpc_cc_library(
     deps = [
         "grpc_common",
         "grpc_lb_policy_grpclb",
+        "grpc_lb_policy_xds",
     ],
 )
 
@@ -294,6 +294,7 @@ grpc_cc_library(
     deps = [
         "grpc_common",
         "grpc_lb_policy_grpclb_secure",
+        "grpc_lb_policy_xds_secure",
         "grpc_secure",
         "grpc_transport_chttp2_client_secure",
         "grpc_transport_chttp2_server_secure",
@@ -820,6 +821,7 @@ grpc_cc_library(
         "src/core/lib/transport/timeout_encoding.cc",
         "src/core/lib/transport/transport.cc",
         "src/core/lib/transport/transport_op_string.cc",
+        "src/core/lib/uri/uri_parser.cc",
     ],
     hdrs = [
         "src/core/lib/avl/avl.h",
@@ -954,6 +956,7 @@ grpc_cc_library(
         "src/core/lib/transport/timeout_encoding.h",
         "src/core/lib/transport/transport.h",
         "src/core/lib/transport/transport_impl.h",
+        "src/core/lib/uri/uri_parser.h",
     ],
     external_deps = [
         "zlib",
@@ -1038,6 +1041,7 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/client_channel_factory.cc",
         "src/core/ext/filters/client_channel/client_channel_plugin.cc",
         "src/core/ext/filters/client_channel/connector.cc",
+        "src/core/ext/filters/client_channel/health/health_check_client.cc",
         "src/core/ext/filters/client_channel/http_connect_handshaker.cc",
         "src/core/ext/filters/client_channel/http_proxy.cc",
         "src/core/ext/filters/client_channel/lb_policy.cc",
@@ -1052,7 +1056,6 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/retry_throttle.cc",
         "src/core/ext/filters/client_channel/subchannel.cc",
         "src/core/ext/filters/client_channel/subchannel_index.cc",
-        "src/core/ext/filters/client_channel/uri_parser.cc",
     ],
     hdrs = [
         "src/core/ext/filters/client_channel/backup_poller.h",
@@ -1060,6 +1063,7 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/client_channel_channelz.h",
         "src/core/ext/filters/client_channel/client_channel_factory.h",
         "src/core/ext/filters/client_channel/connector.h",
+        "src/core/ext/filters/client_channel/health/health_check_client.h",
         "src/core/ext/filters/client_channel/http_connect_handshaker.h",
         "src/core/ext/filters/client_channel/http_proxy.h",
         "src/core/ext/filters/client_channel/lb_policy.h",
@@ -1075,7 +1079,6 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/retry_throttle.h",
         "src/core/ext/filters/client_channel/subchannel.h",
         "src/core/ext/filters/client_channel/subchannel_index.h",
-        "src/core/ext/filters/client_channel/uri_parser.h",
     ],
     language = "c++",
     deps = [
@@ -1087,6 +1090,7 @@ grpc_cc_library(
         "orphanable",
         "ref_counted",
         "ref_counted_ptr",
+        "health_proto",
     ],
 )
 
@@ -1198,6 +1202,38 @@ grpc_cc_library(
     ],
 )
 
+grpc_cc_library(
+    name = "health_proto",
+    srcs = [
+        "src/core/ext/filters/client_channel/health/health.pb.c",
+    ],
+    hdrs = [
+        "src/core/ext/filters/client_channel/health/health.pb.h",
+    ],
+    external_deps = [
+        "nanopb",
+    ],
+    language = "c++",
+)
+
+grpc_cc_library(
+    name = "grpclb_proto",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c",
+        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c",
+        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c",
+    ],
+    hdrs = [
+        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h",
+        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h",
+        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h",
+    ],
+    external_deps = [
+        "nanopb",
+    ],
+    language = "c++",
+)
+
 grpc_cc_library(
     name = "grpc_lb_policy_grpclb",
     srcs = [
@@ -1206,9 +1242,6 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c",
     ],
     hdrs = [
         "src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h",
@@ -1216,9 +1249,6 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h",
     ],
     external_deps = [
         "nanopb",
@@ -1228,6 +1258,7 @@ grpc_cc_library(
         "grpc_base",
         "grpc_client_channel",
         "grpc_resolver_fake",
+        "grpclb_proto",
     ],
 )
 
@@ -1239,9 +1270,6 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c",
     ],
     hdrs = [
         "src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h",
@@ -1249,9 +1277,6 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h",
-        "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h",
     ],
     external_deps = [
         "nanopb",
@@ -1262,6 +1287,60 @@ grpc_cc_library(
         "grpc_client_channel",
         "grpc_resolver_fake",
         "grpc_secure",
+        "grpclb_proto",
+    ],
+)
+
+grpc_cc_library(
+    name = "grpc_lb_policy_xds",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc",
+    ],
+    hdrs = [
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h",
+    ],
+    external_deps = [
+        "nanopb",
+    ],
+    language = "c++",
+    deps = [
+        "grpc_base",
+        "grpc_client_channel",
+        "grpc_resolver_fake",
+        "grpclb_proto",
+    ],
+)
+
+grpc_cc_library(
+    name = "grpc_lb_policy_xds_secure",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc",
+    ],
+    hdrs = [
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h",
+    ],
+    external_deps = [
+        "nanopb",
+    ],
+    language = "c++",
+    deps = [
+        "grpc_base",
+        "grpc_client_channel",
+        "grpc_resolver_fake",
+        "grpc_secure",
+        "grpclb_proto",
     ],
 )
 
@@ -1503,11 +1582,14 @@ grpc_cc_library(
         "src/core/lib/security/credentials/oauth2/oauth2_credentials.cc",
         "src/core/lib/security/credentials/plugin/plugin_credentials.cc",
         "src/core/lib/security/credentials/ssl/ssl_credentials.cc",
-        "src/core/lib/security/security_connector/alts_security_connector.cc",
+        "src/core/lib/security/security_connector/alts/alts_security_connector.cc",
+        "src/core/lib/security/security_connector/fake/fake_security_connector.cc",
         "src/core/lib/security/security_connector/load_system_roots_fallback.cc",
         "src/core/lib/security/security_connector/load_system_roots_linux.cc",
-        "src/core/lib/security/security_connector/local_security_connector.cc",
+        "src/core/lib/security/security_connector/local/local_security_connector.cc",
         "src/core/lib/security/security_connector/security_connector.cc",
+        "src/core/lib/security/security_connector/ssl_utils.cc",
+        "src/core/lib/security/security_connector/ssl/ssl_security_connector.cc",
         "src/core/lib/security/transport/client_auth_filter.cc",
         "src/core/lib/security/transport/secure_endpoint.cc",
         "src/core/lib/security/transport/security_handshaker.cc",
@@ -1519,6 +1601,7 @@ grpc_cc_library(
     ],
     hdrs = [
         "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds.h",
         "src/core/lib/security/context/security_context.h",
         "src/core/lib/security/credentials/alts/alts_credentials.h",
         "src/core/lib/security/credentials/composite/composite_credentials.h",
@@ -1533,11 +1616,14 @@ grpc_cc_library(
         "src/core/lib/security/credentials/oauth2/oauth2_credentials.h",
         "src/core/lib/security/credentials/plugin/plugin_credentials.h",
         "src/core/lib/security/credentials/ssl/ssl_credentials.h",
-        "src/core/lib/security/security_connector/alts_security_connector.h",
+        "src/core/lib/security/security_connector/alts/alts_security_connector.h",
+        "src/core/lib/security/security_connector/fake/fake_security_connector.h",
         "src/core/lib/security/security_connector/load_system_roots.h",
         "src/core/lib/security/security_connector/load_system_roots_linux.h",
-        "src/core/lib/security/security_connector/local_security_connector.h",
+        "src/core/lib/security/security_connector/local/local_security_connector.h",
         "src/core/lib/security/security_connector/security_connector.h",
+        "src/core/lib/security/security_connector/ssl_utils.h",
+        "src/core/lib/security/security_connector/ssl/ssl_security_connector.h",
         "src/core/lib/security/transport/auth_filters.h",
         "src/core/lib/security/transport/secure_endpoint.h",
         "src/core/lib/security/transport/security_handshaker.h",
@@ -1923,6 +2009,7 @@ grpc_cc_library(
     deps = [
         "grpc",
         "grpc++_codegen_base",
+        "health_proto",
     ],
 )
 
@@ -1935,6 +2022,7 @@ grpc_cc_library(
     deps = [
         "grpc++_codegen_base",
         "grpc_unsecure",
+        "health_proto",
     ],
 )
 
@@ -1978,6 +2066,8 @@ grpc_cc_library(
         "include/grpcpp/impl/codegen/byte_buffer.h",
         "include/grpcpp/impl/codegen/call.h",
         "include/grpcpp/impl/codegen/call_hook.h",
+        "include/grpcpp/impl/codegen/call_op_set.h",
+        "include/grpcpp/impl/codegen/call_op_set_interface.h",
         "include/grpcpp/impl/codegen/callback_common.h",
         "include/grpcpp/impl/codegen/channel_interface.h",
         "include/grpcpp/impl/codegen/client_callback.h",
@@ -1990,14 +2080,18 @@ grpc_cc_library(
         "include/grpcpp/impl/codegen/core_codegen_interface.h",
         "include/grpcpp/impl/codegen/create_auth_context.h",
         "include/grpcpp/impl/codegen/grpc_library.h",
+        "include/grpcpp/impl/codegen/intercepted_channel.h",
         "include/grpcpp/impl/codegen/interceptor.h",
+        "include/grpcpp/impl/codegen/interceptor_common.h",
         "include/grpcpp/impl/codegen/metadata_map.h",
         "include/grpcpp/impl/codegen/method_handler_impl.h",
         "include/grpcpp/impl/codegen/rpc_method.h",
         "include/grpcpp/impl/codegen/rpc_service_method.h",
         "include/grpcpp/impl/codegen/security/auth_context.h",
         "include/grpcpp/impl/codegen/serialization_traits.h",
+        "include/grpcpp/impl/codegen/server_callback.h",
         "include/grpcpp/impl/codegen/server_context.h",
+        "include/grpcpp/impl/codegen/server_interceptor.h",
         "include/grpcpp/impl/codegen/server_interface.h",
         "include/grpcpp/impl/codegen/service_type.h",
         "include/grpcpp/impl/codegen/slice.h",
@@ -2137,7 +2231,6 @@ grpc_cc_library(
 grpc_cc_library(
     name = "grpc_opencensus_plugin",
     srcs = [
-        "src/core/ext/filters/census/grpc_context.cc",
         "src/cpp/ext/filters/census/channel_filter.cc",
         "src/cpp/ext/filters/census/client_filter.cc",
         "src/cpp/ext/filters/census/context.cc",

CMakeLists.txt

@@ -328,10 +328,10 @@ add_dependencies(buildtests_c grpc_jwt_verifier_test)
 add_dependencies(buildtests_c grpc_security_connector_test)
 add_dependencies(buildtests_c grpc_ssl_credentials_test)
 if(_gRPC_PLATFORM_LINUX)
-add_dependencies(buildtests_c handshake_client)
+add_dependencies(buildtests_c handshake_client_ssl)
 endif()
 if(_gRPC_PLATFORM_LINUX)
-add_dependencies(buildtests_c handshake_server)
+add_dependencies(buildtests_c handshake_server_ssl)
 endif()
 if(_gRPC_PLATFORM_LINUX)
 add_dependencies(buildtests_c handshake_server_with_readahead_handshaker)
@@ -359,10 +359,10 @@ add_dependencies(buildtests_c json_stream_error_test)
 add_dependencies(buildtests_c json_test)
 add_dependencies(buildtests_c lame_client_test)
 add_dependencies(buildtests_c load_file_test)
-add_dependencies(buildtests_c memory_profile_client)
-add_dependencies(buildtests_c memory_profile_server)
+add_dependencies(buildtests_c memory_usage_client)
+add_dependencies(buildtests_c memory_usage_server)
 if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
-add_dependencies(buildtests_c memory_profile_test)
+add_dependencies(buildtests_c memory_usage_test)
 endif()
 add_dependencies(buildtests_c message_compress_test)
 add_dependencies(buildtests_c minimal_stack_is_minimal_test)
@@ -488,7 +488,6 @@ add_dependencies(buildtests_c h2_sockpair_1byte_nosec_test)
 if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
 add_dependencies(buildtests_c h2_uds_nosec_test)
 endif()
-add_dependencies(buildtests_c inproc_nosec_test)
 add_dependencies(buildtests_c alts_credentials_fuzzer_one_entry)
 add_dependencies(buildtests_c api_fuzzer_one_entry)
 add_dependencies(buildtests_c client_fuzzer_one_entry)
@@ -585,6 +584,7 @@ if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
 add_dependencies(buildtests_cxx client_crash_test)
 endif()
 add_dependencies(buildtests_cxx client_crash_test_server)
+add_dependencies(buildtests_cxx client_interceptors_end2end_test)
 add_dependencies(buildtests_cxx client_lb_end2end_test)
 add_dependencies(buildtests_cxx codegen_test_full)
 add_dependencies(buildtests_cxx codegen_test_minimal)
@@ -665,6 +665,7 @@ add_dependencies(buildtests_cxx server_crash_test)
 endif()
 add_dependencies(buildtests_cxx server_crash_test_client)
 add_dependencies(buildtests_cxx server_early_return_test)
+add_dependencies(buildtests_cxx server_interceptors_end2end_test)
 add_dependencies(buildtests_cxx server_request_call_test)
 add_dependencies(buildtests_cxx shutdown_test)
 add_dependencies(buildtests_cxx slice_hash_table_test)
@@ -1124,6 +1125,7 @@ add_library(grpc
   src/core/lib/transport/timeout_encoding.cc
   src/core/lib/transport/transport.cc
   src/core/lib/transport/transport_op_string.cc
+  src/core/lib/uri/uri_parser.cc
   src/core/lib/debug/trace.cc
   src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc
   src/core/ext/transport/chttp2/transport/bin_decoder.cc
@@ -1170,11 +1172,14 @@ add_library(grpc
   src/core/lib/security/credentials/oauth2/oauth2_credentials.cc
   src/core/lib/security/credentials/plugin/plugin_credentials.cc
   src/core/lib/security/credentials/ssl/ssl_credentials.cc
-  src/core/lib/security/security_connector/alts_security_connector.cc
+  src/core/lib/security/security_connector/alts/alts_security_connector.cc
+  src/core/lib/security/security_connector/fake/fake_security_connector.cc
   src/core/lib/security/security_connector/load_system_roots_fallback.cc
   src/core/lib/security/security_connector/load_system_roots_linux.cc
-  src/core/lib/security/security_connector/local_security_connector.cc
+  src/core/lib/security/security_connector/local/local_security_connector.cc
   src/core/lib/security/security_connector/security_connector.cc
+  src/core/lib/security/security_connector/ssl/ssl_security_connector.cc
+  src/core/lib/security/security_connector/ssl_utils.cc
   src/core/lib/security/transport/client_auth_filter.cc
   src/core/lib/security/transport/secure_endpoint.cc
   src/core/lib/security/transport/security_handshaker.cc
@@ -1229,6 +1234,7 @@ add_library(grpc
   src/core/ext/filters/client_channel/client_channel_factory.cc
   src/core/ext/filters/client_channel/client_channel_plugin.cc
   src/core/ext/filters/client_channel/connector.cc
+  src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
@@ -1243,8 +1249,8 @@ add_library(grpc
   src/core/ext/filters/client_channel/retry_throttle.cc
   src/core/ext/filters/client_channel/subchannel.cc
   src/core/ext/filters/client_channel/subchannel_index.cc
-  src/core/ext/filters/client_channel/uri_parser.cc
   src/core/ext/filters/deadline/deadline_filter.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
   src/core/tsi/alts_transport_security.cc
   src/core/tsi/fake_transport_security.cc
   src/core/tsi/local_transport_security.cc
@@ -1264,10 +1270,14 @@ add_library(grpc
   src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
+  src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c
   src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c
   src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
-  src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc
   src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
   src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
@@ -1536,6 +1546,7 @@ add_library(grpc_cronet
   src/core/lib/transport/timeout_encoding.cc
   src/core/lib/transport/transport.cc
   src/core/lib/transport/transport_op_string.cc
+  src/core/lib/uri/uri_parser.cc
   src/core/lib/debug/trace.cc
   src/core/ext/transport/cronet/client/secure/cronet_channel_create.cc
   src/core/ext/transport/cronet/transport/cronet_api_dummy.cc
@@ -1575,6 +1586,7 @@ add_library(grpc_cronet
   src/core/ext/filters/client_channel/client_channel_factory.cc
   src/core/ext/filters/client_channel/client_channel_plugin.cc
   src/core/ext/filters/client_channel/connector.cc
+  src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
@@ -1589,8 +1601,11 @@ add_library(grpc_cronet
   src/core/ext/filters/client_channel/retry_throttle.cc
   src/core/ext/filters/client_channel/subchannel.cc
   src/core/ext/filters/client_channel/subchannel_index.cc
-  src/core/ext/filters/client_channel/uri_parser.cc
   src/core/ext/filters/deadline/deadline_filter.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
+  third_party/nanopb/pb_common.c
+  third_party/nanopb/pb_decode.c
+  third_party/nanopb/pb_encode.c
   src/core/lib/http/httpcli_security_connector.cc
   src/core/lib/security/context/security_context.cc
   src/core/lib/security/credentials/alts/alts_credentials.cc
@@ -1608,11 +1623,14 @@ add_library(grpc_cronet
   src/core/lib/security/credentials/oauth2/oauth2_credentials.cc
   src/core/lib/security/credentials/plugin/plugin_credentials.cc
   src/core/lib/security/credentials/ssl/ssl_credentials.cc
-  src/core/lib/security/security_connector/alts_security_connector.cc
+  src/core/lib/security/security_connector/alts/alts_security_connector.cc
+  src/core/lib/security/security_connector/fake/fake_security_connector.cc
   src/core/lib/security/security_connector/load_system_roots_fallback.cc
   src/core/lib/security/security_connector/load_system_roots_linux.cc
-  src/core/lib/security/security_connector/local_security_connector.cc
+  src/core/lib/security/security_connector/local/local_security_connector.cc
   src/core/lib/security/security_connector/security_connector.cc
+  src/core/lib/security/security_connector/ssl/ssl_security_connector.cc
+  src/core/lib/security/security_connector/ssl_utils.cc
   src/core/lib/security/transport/client_auth_filter.cc
   src/core/lib/security/transport/secure_endpoint.cc
   src/core/lib/security/transport/security_handshaker.cc
@@ -1652,9 +1670,6 @@ add_library(grpc_cronet
   src/core/tsi/alts/handshaker/altscontext.pb.c
   src/core/tsi/alts/handshaker/handshaker.pb.c
   src/core/tsi/alts/handshaker/transport_security_common.pb.c
-  third_party/nanopb/pb_common.c
-  third_party/nanopb/pb_decode.c
-  third_party/nanopb/pb_encode.c
   src/core/tsi/transport_security.cc
   src/core/ext/transport/chttp2/client/insecure/channel_create.cc
   src/core/ext/transport/chttp2/client/insecure/channel_create_posix.cc
@@ -1934,6 +1949,7 @@ add_library(grpc_test_util
   src/core/lib/transport/timeout_encoding.cc
   src/core/lib/transport/transport.cc
   src/core/lib/transport/transport_op_string.cc
+  src/core/lib/uri/uri_parser.cc
   src/core/lib/debug/trace.cc
   src/core/ext/filters/client_channel/backup_poller.cc
   src/core/ext/filters/client_channel/channel_connectivity.cc
@@ -1942,6 +1958,7 @@ add_library(grpc_test_util
   src/core/ext/filters/client_channel/client_channel_factory.cc
   src/core/ext/filters/client_channel/client_channel_plugin.cc
   src/core/ext/filters/client_channel/connector.cc
+  src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
@@ -1956,8 +1973,11 @@ add_library(grpc_test_util
   src/core/ext/filters/client_channel/retry_throttle.cc
   src/core/ext/filters/client_channel/subchannel.cc
   src/core/ext/filters/client_channel/subchannel_index.cc
-  src/core/ext/filters/client_channel/uri_parser.cc
   src/core/ext/filters/deadline/deadline_filter.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
+  third_party/nanopb/pb_common.c
+  third_party/nanopb/pb_decode.c
+  third_party/nanopb/pb_encode.c
   src/core/ext/transport/chttp2/transport/bin_decoder.cc
   src/core/ext/transport/chttp2/transport/bin_encoder.cc
   src/core/ext/transport/chttp2/transport/chttp2_plugin.cc
@@ -2248,6 +2268,7 @@ add_library(grpc_test_util_unsecure
   src/core/lib/transport/timeout_encoding.cc
   src/core/lib/transport/transport.cc
   src/core/lib/transport/transport_op_string.cc
+  src/core/lib/uri/uri_parser.cc
   src/core/lib/debug/trace.cc
   src/core/ext/filters/client_channel/backup_poller.cc
   src/core/ext/filters/client_channel/channel_connectivity.cc
@@ -2256,6 +2277,7 @@ add_library(grpc_test_util_unsecure
   src/core/ext/filters/client_channel/client_channel_factory.cc
   src/core/ext/filters/client_channel/client_channel_plugin.cc
   src/core/ext/filters/client_channel/connector.cc
+  src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
@@ -2270,8 +2292,11 @@ add_library(grpc_test_util_unsecure
   src/core/ext/filters/client_channel/retry_throttle.cc
   src/core/ext/filters/client_channel/subchannel.cc
   src/core/ext/filters/client_channel/subchannel_index.cc
-  src/core/ext/filters/client_channel/uri_parser.cc
   src/core/ext/filters/deadline/deadline_filter.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
+  third_party/nanopb/pb_common.c
+  third_party/nanopb/pb_decode.c
+  third_party/nanopb/pb_encode.c
   src/core/ext/transport/chttp2/transport/bin_decoder.cc
   src/core/ext/transport/chttp2/transport/bin_encoder.cc
   src/core/ext/transport/chttp2/transport/chttp2_plugin.cc
@@ -2541,6 +2566,7 @@ add_library(grpc_unsecure
   src/core/lib/transport/timeout_encoding.cc
   src/core/lib/transport/transport.cc
   src/core/lib/transport/transport_op_string.cc
+  src/core/lib/uri/uri_parser.cc
   src/core/lib/debug/trace.cc
   src/core/ext/transport/chttp2/server/insecure/server_chttp2.cc
   src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.cc
@@ -2583,6 +2609,7 @@ add_library(grpc_unsecure
   src/core/ext/filters/client_channel/client_channel_factory.cc
   src/core/ext/filters/client_channel/client_channel_plugin.cc
   src/core/ext/filters/client_channel/connector.cc
+  src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
@@ -2597,8 +2624,11 @@ add_library(grpc_unsecure
   src/core/ext/filters/client_channel/retry_throttle.cc
   src/core/ext/filters/client_channel/subchannel.cc
   src/core/ext/filters/client_channel/subchannel_index.cc
-  src/core/ext/filters/client_channel/uri_parser.cc
   src/core/ext/filters/deadline/deadline_filter.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
+  third_party/nanopb/pb_common.c
+  third_party/nanopb/pb_decode.c
+  third_party/nanopb/pb_encode.c
   src/core/ext/transport/inproc/inproc_plugin.cc
   src/core/ext/transport/inproc/inproc_transport.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
@@ -2620,9 +2650,10 @@ add_library(grpc_unsecure
   src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c
   src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c
   src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
-  third_party/nanopb/pb_common.c
-  third_party/nanopb/pb_decode.c
-  third_party/nanopb/pb_encode.c
+  src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc
   src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
   src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
   src/core/ext/filters/census/grpc_context.cc
@@ -2849,7 +2880,6 @@ add_library(grpc++
   src/cpp/server/create_default_thread_pool.cc
   src/cpp/server/dynamic_thread_pool.cc
   src/cpp/server/health/default_health_check_service.cc
-  src/cpp/server/health/health.pb.c
   src/cpp/server/health/health_check_service.cc
   src/cpp/server/health/health_check_service_server_builder_option.cc
   src/cpp/server/server_builder.cc
@@ -2862,6 +2892,10 @@ add_library(grpc++
   src/cpp/util/status.cc
   src/cpp/util/string_ref.cc
   src/cpp/util/time_cc.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
+  third_party/nanopb/pb_common.c
+  third_party/nanopb/pb_decode.c
+  third_party/nanopb/pb_encode.c
   src/cpp/codegen/codegen_init.cc
 )
 
@@ -2986,6 +3020,7 @@ foreach(_hdr
   include/grpcpp/support/config.h
   include/grpcpp/support/proto_buffer_reader.h
   include/grpcpp/support/proto_buffer_writer.h
+  include/grpcpp/support/server_callback.h
   include/grpcpp/support/slice.h
   include/grpcpp/support/status.h
   include/grpcpp/support/status_code_enum.h
@@ -3080,6 +3115,8 @@ foreach(_hdr
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
+  include/grpcpp/impl/codegen/call_op_set.h
+  include/grpcpp/impl/codegen/call_op_set_interface.h
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
@@ -3092,14 +3129,18 @@ foreach(_hdr
   include/grpcpp/impl/codegen/core_codegen_interface.h
   include/grpcpp/impl/codegen/create_auth_context.h
   include/grpcpp/impl/codegen/grpc_library.h
+  include/grpcpp/impl/codegen/intercepted_channel.h
   include/grpcpp/impl/codegen/interceptor.h
+  include/grpcpp/impl/codegen/interceptor_common.h
   include/grpcpp/impl/codegen/metadata_map.h
   include/grpcpp/impl/codegen/method_handler_impl.h
   include/grpcpp/impl/codegen/rpc_method.h
   include/grpcpp/impl/codegen/rpc_service_method.h
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
+  include/grpcpp/impl/codegen/server_callback.h
   include/grpcpp/impl/codegen/server_context.h
+  include/grpcpp/impl/codegen/server_interceptor.h
   include/grpcpp/impl/codegen/server_interface.h
   include/grpcpp/impl/codegen/service_type.h
   include/grpcpp/impl/codegen/slice.h
@@ -3210,7 +3251,6 @@ add_library(grpc++_cronet
   src/cpp/server/create_default_thread_pool.cc
   src/cpp/server/dynamic_thread_pool.cc
   src/cpp/server/health/default_health_check_service.cc
-  src/cpp/server/health/health.pb.c
   src/cpp/server/health/health_check_service.cc
   src/cpp/server/health/health_check_service_server_builder_option.cc
   src/cpp/server/server_builder.cc
@@ -3223,6 +3263,10 @@ add_library(grpc++_cronet
   src/cpp/util/status.cc
   src/cpp/util/string_ref.cc
   src/cpp/util/time_cc.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
+  third_party/nanopb/pb_common.c
+  third_party/nanopb/pb_decode.c
+  third_party/nanopb/pb_encode.c
   src/cpp/codegen/codegen_init.cc
   src/core/ext/transport/chttp2/client/insecure/channel_create.cc
   src/core/ext/transport/chttp2/client/insecure/channel_create_posix.cc
@@ -3400,6 +3444,7 @@ add_library(grpc++_cronet
   src/core/lib/transport/timeout_encoding.cc
   src/core/lib/transport/transport.cc
   src/core/lib/transport/transport_op_string.cc
+  src/core/lib/uri/uri_parser.cc
   src/core/lib/debug/trace.cc
   src/core/ext/transport/chttp2/alpn/alpn.cc
   src/core/ext/filters/http/client/http_client_filter.cc
@@ -3413,6 +3458,7 @@ add_library(grpc++_cronet
   src/core/ext/filters/client_channel/client_channel_factory.cc
   src/core/ext/filters/client_channel/client_channel_plugin.cc
   src/core/ext/filters/client_channel/connector.cc
+  src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
@@ -3427,7 +3473,6 @@ add_library(grpc++_cronet
   src/core/ext/filters/client_channel/retry_throttle.cc
   src/core/ext/filters/client_channel/subchannel.cc
   src/core/ext/filters/client_channel/subchannel_index.cc
-  src/core/ext/filters/client_channel/uri_parser.cc
   src/core/ext/filters/deadline/deadline_filter.cc
   src/core/ext/transport/chttp2/server/insecure/server_chttp2.cc
   src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.cc
@@ -3557,6 +3602,7 @@ foreach(_hdr
   include/grpcpp/support/config.h
   include/grpcpp/support/proto_buffer_reader.h
   include/grpcpp/support/proto_buffer_writer.h
+  include/grpcpp/support/server_callback.h
   include/grpcpp/support/slice.h
   include/grpcpp/support/status.h
   include/grpcpp/support/status_code_enum.h
@@ -3651,6 +3697,8 @@ foreach(_hdr
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
+  include/grpcpp/impl/codegen/call_op_set.h
+  include/grpcpp/impl/codegen/call_op_set_interface.h
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
@@ -3663,14 +3711,18 @@ foreach(_hdr
   include/grpcpp/impl/codegen/core_codegen_interface.h
   include/grpcpp/impl/codegen/create_auth_context.h
   include/grpcpp/impl/codegen/grpc_library.h
+  include/grpcpp/impl/codegen/intercepted_channel.h
   include/grpcpp/impl/codegen/interceptor.h
+  include/grpcpp/impl/codegen/interceptor_common.h
   include/grpcpp/impl/codegen/metadata_map.h
   include/grpcpp/impl/codegen/method_handler_impl.h
   include/grpcpp/impl/codegen/rpc_method.h
   include/grpcpp/impl/codegen/rpc_service_method.h
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
+  include/grpcpp/impl/codegen/server_callback.h
   include/grpcpp/impl/codegen/server_context.h
+  include/grpcpp/impl/codegen/server_interceptor.h
   include/grpcpp/impl/codegen/server_interface.h
   include/grpcpp/impl/codegen/service_type.h
   include/grpcpp/impl/codegen/slice.h
@@ -4060,6 +4112,8 @@ foreach(_hdr
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
+  include/grpcpp/impl/codegen/call_op_set.h
+  include/grpcpp/impl/codegen/call_op_set_interface.h
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
@@ -4072,14 +4126,18 @@ foreach(_hdr
   include/grpcpp/impl/codegen/core_codegen_interface.h
   include/grpcpp/impl/codegen/create_auth_context.h
   include/grpcpp/impl/codegen/grpc_library.h
+  include/grpcpp/impl/codegen/intercepted_channel.h
   include/grpcpp/impl/codegen/interceptor.h
+  include/grpcpp/impl/codegen/interceptor_common.h
   include/grpcpp/impl/codegen/metadata_map.h
   include/grpcpp/impl/codegen/method_handler_impl.h
   include/grpcpp/impl/codegen/rpc_method.h
   include/grpcpp/impl/codegen/rpc_service_method.h
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
+  include/grpcpp/impl/codegen/server_callback.h
   include/grpcpp/impl/codegen/server_context.h
+  include/grpcpp/impl/codegen/server_interceptor.h
   include/grpcpp/impl/codegen/server_interface.h
   include/grpcpp/impl/codegen/service_type.h
   include/grpcpp/impl/codegen/slice.h
@@ -4241,6 +4299,8 @@ foreach(_hdr
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
+  include/grpcpp/impl/codegen/call_op_set.h
+  include/grpcpp/impl/codegen/call_op_set_interface.h
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
@@ -4253,14 +4313,18 @@ foreach(_hdr
   include/grpcpp/impl/codegen/core_codegen_interface.h
   include/grpcpp/impl/codegen/create_auth_context.h
   include/grpcpp/impl/codegen/grpc_library.h
+  include/grpcpp/impl/codegen/intercepted_channel.h
   include/grpcpp/impl/codegen/interceptor.h
+  include/grpcpp/impl/codegen/interceptor_common.h
   include/grpcpp/impl/codegen/metadata_map.h
   include/grpcpp/impl/codegen/method_handler_impl.h
   include/grpcpp/impl/codegen/rpc_method.h
   include/grpcpp/impl/codegen/rpc_service_method.h
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
+  include/grpcpp/impl/codegen/server_callback.h
   include/grpcpp/impl/codegen/server_context.h
+  include/grpcpp/impl/codegen/server_interceptor.h
   include/grpcpp/impl/codegen/server_interface.h
   include/grpcpp/impl/codegen/service_type.h
   include/grpcpp/impl/codegen/slice.h
@@ -4333,7 +4397,6 @@ add_library(grpc++_unsecure
   src/cpp/server/create_default_thread_pool.cc
   src/cpp/server/dynamic_thread_pool.cc
   src/cpp/server/health/default_health_check_service.cc
-  src/cpp/server/health/health.pb.c
   src/cpp/server/health/health_check_service.cc
   src/cpp/server/health/health_check_service_server_builder_option.cc
   src/cpp/server/server_builder.cc
@@ -4346,6 +4409,10 @@ add_library(grpc++_unsecure
   src/cpp/util/status.cc
   src/cpp/util/string_ref.cc
   src/cpp/util/time_cc.cc
+  src/core/ext/filters/client_channel/health/health.pb.c
+  third_party/nanopb/pb_common.c
+  third_party/nanopb/pb_decode.c
+  third_party/nanopb/pb_encode.c
   src/cpp/codegen/codegen_init.cc
 )
 
@@ -4469,6 +4536,7 @@ foreach(_hdr
   include/grpcpp/support/config.h
   include/grpcpp/support/proto_buffer_reader.h
   include/grpcpp/support/proto_buffer_writer.h
+  include/grpcpp/support/server_callback.h
   include/grpcpp/support/slice.h
   include/grpcpp/support/status.h
   include/grpcpp/support/status_code_enum.h
@@ -4563,6 +4631,8 @@ foreach(_hdr
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
+  include/grpcpp/impl/codegen/call_op_set.h
+  include/grpcpp/impl/codegen/call_op_set_interface.h
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
@@ -4575,14 +4645,18 @@ foreach(_hdr
   include/grpcpp/impl/codegen/core_codegen_interface.h
   include/grpcpp/impl/codegen/create_auth_context.h
   include/grpcpp/impl/codegen/grpc_library.h
+  include/grpcpp/impl/codegen/intercepted_channel.h
   include/grpcpp/impl/codegen/interceptor.h
+  include/grpcpp/impl/codegen/interceptor_common.h
   include/grpcpp/impl/codegen/metadata_map.h
   include/grpcpp/impl/codegen/method_handler_impl.h
   include/grpcpp/impl/codegen/rpc_method.h
   include/grpcpp/impl/codegen/rpc_service_method.h
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
+  include/grpcpp/impl/codegen/server_callback.h
   include/grpcpp/impl/codegen/server_context.h
+  include/grpcpp/impl/codegen/server_interceptor.h
   include/grpcpp/impl/codegen/server_interface.h
   include/grpcpp/impl/codegen/service_type.h
   include/grpcpp/impl/codegen/slice.h
@@ -8041,12 +8115,12 @@ target_link_libraries(grpc_verify_jwt
 if (gRPC_BUILD_TESTS)
 if(_gRPC_PLATFORM_LINUX)
 
-add_executable(handshake_client
+add_executable(handshake_client_ssl
   test/core/handshake/client_ssl.cc
 )
 
 
-target_include_directories(handshake_client
+target_include_directories(handshake_client_ssl
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
   PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
@@ -8059,7 +8133,7 @@ target_include_directories(handshake_client
   PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
 )
 
-target_link_libraries(handshake_client
+target_link_libraries(handshake_client_ssl
   ${_gRPC_SSL_LIBRARIES}
   ${_gRPC_ALLTARGETS_LIBRARIES}
   grpc_test_util
@@ -8070,8 +8144,8 @@ target_link_libraries(handshake_client
 
   # avoid dependency on libstdc++
   if (_gRPC_CORE_NOSTDCXX_FLAGS)
-    set_target_properties(handshake_client PROPERTIES LINKER_LANGUAGE C)
-    target_compile_options(handshake_client PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
+    set_target_properties(handshake_client_ssl PROPERTIES LINKER_LANGUAGE C)
+    target_compile_options(handshake_client_ssl PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
   endif()
 
 endif()
@@ -8079,13 +8153,13 @@ endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 if(_gRPC_PLATFORM_LINUX)
 
-add_executable(handshake_server
+add_executable(handshake_server_ssl
   test/core/handshake/server_ssl.cc
   test/core/handshake/server_ssl_common.cc
 )
 
 
-target_include_directories(handshake_server
+target_include_directories(handshake_server_ssl
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
   PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
@@ -8098,7 +8172,7 @@ target_include_directories(handshake_server
   PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
 )
 
-target_link_libraries(handshake_server
+target_link_libraries(handshake_server_ssl
   ${_gRPC_SSL_LIBRARIES}
   ${_gRPC_ALLTARGETS_LIBRARIES}
   grpc_test_util
@@ -8109,8 +8183,8 @@ target_link_libraries(handshake_server
 
   # avoid dependency on libstdc++
   if (_gRPC_CORE_NOSTDCXX_FLAGS)
-    set_target_properties(handshake_server PROPERTIES LINKER_LANGUAGE C)
-    target_compile_options(handshake_server PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
+    set_target_properties(handshake_server_ssl PROPERTIES LINKER_LANGUAGE C)
+    target_compile_options(handshake_server_ssl PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
   endif()
 
 endif()
@@ -8756,12 +8830,12 @@ target_link_libraries(load_file_test
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
-add_executable(memory_profile_client
+add_executable(memory_usage_client
   test/core/memory_usage/client.cc
 )
 
 
-target_include_directories(memory_profile_client
+target_include_directories(memory_usage_client
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
   PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
@@ -8774,7 +8848,7 @@ target_include_directories(memory_profile_client
   PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
 )
 
-target_link_libraries(memory_profile_client
+target_link_libraries(memory_usage_client
   ${_gRPC_ALLTARGETS_LIBRARIES}
   grpc_test_util
   grpc
@@ -8784,19 +8858,19 @@ target_link_libraries(memory_profile_client
 
   # avoid dependency on libstdc++
   if (_gRPC_CORE_NOSTDCXX_FLAGS)
-    set_target_properties(memory_profile_client PROPERTIES LINKER_LANGUAGE C)
-    target_compile_options(memory_profile_client PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
+    set_target_properties(memory_usage_client PROPERTIES LINKER_LANGUAGE C)
+    target_compile_options(memory_usage_client PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
   endif()
 
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
-add_executable(memory_profile_server
+add_executable(memory_usage_server
   test/core/memory_usage/server.cc
 )
 
 
-target_include_directories(memory_profile_server
+target_include_directories(memory_usage_server
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
   PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
@@ -8809,7 +8883,7 @@ target_include_directories(memory_profile_server
   PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
 )
 
-target_link_libraries(memory_profile_server
+target_link_libraries(memory_usage_server
   ${_gRPC_ALLTARGETS_LIBRARIES}
   grpc_test_util
   grpc
@@ -8819,20 +8893,20 @@ target_link_libraries(memory_profile_server
 
   # avoid dependency on libstdc++
   if (_gRPC_CORE_NOSTDCXX_FLAGS)
-    set_target_properties(memory_profile_server PROPERTIES LINKER_LANGUAGE C)
-    target_compile_options(memory_profile_server PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
+    set_target_properties(memory_usage_server PROPERTIES LINKER_LANGUAGE C)
+    target_compile_options(memory_usage_server PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
   endif()
 
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
 
-add_executable(memory_profile_test
+add_executable(memory_usage_test
   test/core/memory_usage/memory_usage_test.cc
 )
 
 
-target_include_directories(memory_profile_test
+target_include_directories(memory_usage_test
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
   PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
@@ -8845,7 +8919,7 @@ target_include_directories(memory_profile_test
   PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
 )
 
-target_link_libraries(memory_profile_test
+target_link_libraries(memory_usage_test
   ${_gRPC_ALLTARGETS_LIBRARIES}
   grpc_test_util
   grpc
@@ -8855,8 +8929,8 @@ target_link_libraries(memory_profile_test
 
   # avoid dependency on libstdc++
   if (_gRPC_CORE_NOSTDCXX_FLAGS)
-    set_target_properties(memory_profile_test PROPERTIES LINKER_LANGUAGE C)
-    target_compile_options(memory_profile_test PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
+    set_target_properties(memory_usage_test PROPERTIES LINKER_LANGUAGE C)
+    target_compile_options(memory_usage_test PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
   endif()
 
 endif()
@@ -12363,6 +12437,47 @@ target_link_libraries(client_crash_test_server
 )
 
 
+endif (gRPC_BUILD_TESTS)
+if (gRPC_BUILD_TESTS)
+
+add_executable(client_interceptors_end2end_test
+  test/cpp/end2end/client_interceptors_end2end_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+
+target_include_directories(client_interceptors_end2end_test
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
+  PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
+  PRIVATE ${_gRPC_PROTOBUF_INCLUDE_DIR}
+  PRIVATE ${_gRPC_ZLIB_INCLUDE_DIR}
+  PRIVATE ${_gRPC_BENCHMARK_INCLUDE_DIR}
+  PRIVATE ${_gRPC_CARES_INCLUDE_DIR}
+  PRIVATE ${_gRPC_GFLAGS_INCLUDE_DIR}
+  PRIVATE ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
+  PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
+  PRIVATE third_party/googletest/googletest/include
+  PRIVATE third_party/googletest/googletest
+  PRIVATE third_party/googletest/googlemock/include
+  PRIVATE third_party/googletest/googlemock
+  PRIVATE ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(client_interceptors_end2end_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+  grpc++_test_util
+  grpc_test_util
+  grpc++
+  grpc
+  gpr_test_util
+  gpr
+  ${_gRPC_GFLAGS_LIBRARIES}
+)
+
+
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
@@ -15233,6 +15348,47 @@ target_link_libraries(server_early_return_test
 )
 
 
+endif (gRPC_BUILD_TESTS)
+if (gRPC_BUILD_TESTS)
+
+add_executable(server_interceptors_end2end_test
+  test/cpp/end2end/server_interceptors_end2end_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+
+target_include_directories(server_interceptors_end2end_test
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
+  PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
+  PRIVATE ${_gRPC_PROTOBUF_INCLUDE_DIR}
+  PRIVATE ${_gRPC_ZLIB_INCLUDE_DIR}
+  PRIVATE ${_gRPC_BENCHMARK_INCLUDE_DIR}
+  PRIVATE ${_gRPC_CARES_INCLUDE_DIR}
+  PRIVATE ${_gRPC_GFLAGS_INCLUDE_DIR}
+  PRIVATE ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
+  PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
+  PRIVATE third_party/googletest/googletest/include
+  PRIVATE third_party/googletest/googletest
+  PRIVATE third_party/googletest/googlemock/include
+  PRIVATE third_party/googletest/googlemock
+  PRIVATE ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(server_interceptors_end2end_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+  grpc++_test_util
+  grpc_test_util
+  grpc++
+  grpc
+  gpr_test_util
+  gpr
+  ${_gRPC_GFLAGS_LIBRARIES}
+)
+
+
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
@@ -17590,42 +17746,6 @@ endif()
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
-add_executable(inproc_nosec_test
-  test/core/end2end/fixtures/inproc.cc
-)
-
-
-target_include_directories(inproc_nosec_test
-  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
-  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
-  PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
-  PRIVATE ${_gRPC_PROTOBUF_INCLUDE_DIR}
-  PRIVATE ${_gRPC_ZLIB_INCLUDE_DIR}
-  PRIVATE ${_gRPC_BENCHMARK_INCLUDE_DIR}
-  PRIVATE ${_gRPC_CARES_INCLUDE_DIR}
-  PRIVATE ${_gRPC_GFLAGS_INCLUDE_DIR}
-  PRIVATE ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
-  PRIVATE ${_gRPC_NANOPB_INCLUDE_DIR}
-)
-
-target_link_libraries(inproc_nosec_test
-  ${_gRPC_ALLTARGETS_LIBRARIES}
-  end2end_nosec_tests
-  grpc_test_util_unsecure
-  grpc_unsecure
-  gpr_test_util
-  gpr
-)
-
-  # avoid dependency on libstdc++
-  if (_gRPC_CORE_NOSTDCXX_FLAGS)
-    set_target_properties(inproc_nosec_test PROPERTIES LINKER_LANGUAGE C)
-    target_compile_options(inproc_nosec_test PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${_gRPC_CORE_NOSTDCXX_FLAGS}>)
-  endif()
-
-endif (gRPC_BUILD_TESTS)
-if (gRPC_BUILD_TESTS)
-
 add_executable(resolver_component_test_unsecure
   test/cpp/naming/resolver_component_test.cc
   third_party/googletest/googletest/src/gtest-all.cc

Makefile

@@ -1039,8 +1039,8 @@ grpc_print_google_default_creds_token: $(BINDIR)/$(CONFIG)/grpc_print_google_def
 grpc_security_connector_test: $(BINDIR)/$(CONFIG)/grpc_security_connector_test
 grpc_ssl_credentials_test: $(BINDIR)/$(CONFIG)/grpc_ssl_credentials_test
 grpc_verify_jwt: $(BINDIR)/$(CONFIG)/grpc_verify_jwt
-handshake_client: $(BINDIR)/$(CONFIG)/handshake_client
-handshake_server: $(BINDIR)/$(CONFIG)/handshake_server
+handshake_client_ssl: $(BINDIR)/$(CONFIG)/handshake_client_ssl
+handshake_server_ssl: $(BINDIR)/$(CONFIG)/handshake_server_ssl
 handshake_server_with_readahead_handshaker: $(BINDIR)/$(CONFIG)/handshake_server_with_readahead_handshaker
 handshake_verify_peer_options: $(BINDIR)/$(CONFIG)/handshake_verify_peer_options
 histogram_test: $(BINDIR)/$(CONFIG)/histogram_test
@@ -1064,9 +1064,9 @@ json_test: $(BINDIR)/$(CONFIG)/json_test
 lame_client_test: $(BINDIR)/$(CONFIG)/lame_client_test
 load_file_test: $(BINDIR)/$(CONFIG)/load_file_test
 low_level_ping_pong_benchmark: $(BINDIR)/$(CONFIG)/low_level_ping_pong_benchmark
-memory_profile_client: $(BINDIR)/$(CONFIG)/memory_profile_client
-memory_profile_server: $(BINDIR)/$(CONFIG)/memory_profile_server
-memory_profile_test: $(BINDIR)/$(CONFIG)/memory_profile_test
+memory_usage_client: $(BINDIR)/$(CONFIG)/memory_usage_client
+memory_usage_server: $(BINDIR)/$(CONFIG)/memory_usage_server
+memory_usage_test: $(BINDIR)/$(CONFIG)/memory_usage_test
 message_compress_test: $(BINDIR)/$(CONFIG)/message_compress_test
 minimal_stack_is_minimal_test: $(BINDIR)/$(CONFIG)/minimal_stack_is_minimal_test
 multiple_server_queues_test: $(BINDIR)/$(CONFIG)/multiple_server_queues_test
@@ -1164,6 +1164,7 @@ client_callback_end2end_test: $(BINDIR)/$(CONFIG)/client_callback_end2end_test
 client_channel_stress_test: $(BINDIR)/$(CONFIG)/client_channel_stress_test
 client_crash_test: $(BINDIR)/$(CONFIG)/client_crash_test
 client_crash_test_server: $(BINDIR)/$(CONFIG)/client_crash_test_server
+client_interceptors_end2end_test: $(BINDIR)/$(CONFIG)/client_interceptors_end2end_test
 client_lb_end2end_test: $(BINDIR)/$(CONFIG)/client_lb_end2end_test
 codegen_test_full: $(BINDIR)/$(CONFIG)/codegen_test_full
 codegen_test_minimal: $(BINDIR)/$(CONFIG)/codegen_test_minimal
@@ -1229,6 +1230,7 @@ server_context_test_spouse_test: $(BINDIR)/$(CONFIG)/server_context_test_spouse_
 server_crash_test: $(BINDIR)/$(CONFIG)/server_crash_test
 server_crash_test_client: $(BINDIR)/$(CONFIG)/server_crash_test_client
 server_early_return_test: $(BINDIR)/$(CONFIG)/server_early_return_test
+server_interceptors_end2end_test: $(BINDIR)/$(CONFIG)/server_interceptors_end2end_test
 server_request_call_test: $(BINDIR)/$(CONFIG)/server_request_call_test
 shutdown_test: $(BINDIR)/$(CONFIG)/shutdown_test
 slice_hash_table_test: $(BINDIR)/$(CONFIG)/slice_hash_table_test
@@ -1343,7 +1345,6 @@ h2_sockpair_nosec_test: $(BINDIR)/$(CONFIG)/h2_sockpair_nosec_test
 h2_sockpair+trace_nosec_test: $(BINDIR)/$(CONFIG)/h2_sockpair+trace_nosec_test
 h2_sockpair_1byte_nosec_test: $(BINDIR)/$(CONFIG)/h2_sockpair_1byte_nosec_test
 h2_uds_nosec_test: $(BINDIR)/$(CONFIG)/h2_uds_nosec_test
-inproc_nosec_test: $(BINDIR)/$(CONFIG)/inproc_nosec_test
 resolver_component_test_unsecure: $(BINDIR)/$(CONFIG)/resolver_component_test_unsecure
 resolver_component_test: $(BINDIR)/$(CONFIG)/resolver_component_test
 resolver_component_tests_runner_invoker_unsecure: $(BINDIR)/$(CONFIG)/resolver_component_tests_runner_invoker_unsecure
@@ -1491,8 +1492,8 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/grpc_jwt_verifier_test \
   $(BINDIR)/$(CONFIG)/grpc_security_connector_test \
   $(BINDIR)/$(CONFIG)/grpc_ssl_credentials_test \
-  $(BINDIR)/$(CONFIG)/handshake_client \
-  $(BINDIR)/$(CONFIG)/handshake_server \
+  $(BINDIR)/$(CONFIG)/handshake_client_ssl \
+  $(BINDIR)/$(CONFIG)/handshake_server_ssl \
   $(BINDIR)/$(CONFIG)/handshake_server_with_readahead_handshaker \
   $(BINDIR)/$(CONFIG)/handshake_verify_peer_options \
   $(BINDIR)/$(CONFIG)/histogram_test \
@@ -1511,9 +1512,9 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/json_test \
   $(BINDIR)/$(CONFIG)/lame_client_test \
   $(BINDIR)/$(CONFIG)/load_file_test \
-  $(BINDIR)/$(CONFIG)/memory_profile_client \
-  $(BINDIR)/$(CONFIG)/memory_profile_server \
-  $(BINDIR)/$(CONFIG)/memory_profile_test \
+  $(BINDIR)/$(CONFIG)/memory_usage_client \
+  $(BINDIR)/$(CONFIG)/memory_usage_server \
+  $(BINDIR)/$(CONFIG)/memory_usage_test \
   $(BINDIR)/$(CONFIG)/message_compress_test \
   $(BINDIR)/$(CONFIG)/minimal_stack_is_minimal_test \
   $(BINDIR)/$(CONFIG)/multiple_server_queues_test \
@@ -1602,7 +1603,6 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/h2_sockpair+trace_nosec_test \
   $(BINDIR)/$(CONFIG)/h2_sockpair_1byte_nosec_test \
   $(BINDIR)/$(CONFIG)/h2_uds_nosec_test \
-  $(BINDIR)/$(CONFIG)/inproc_nosec_test \
   $(BINDIR)/$(CONFIG)/alts_credentials_fuzzer_one_entry \
   $(BINDIR)/$(CONFIG)/api_fuzzer_one_entry \
   $(BINDIR)/$(CONFIG)/client_fuzzer_one_entry \
@@ -1669,6 +1669,7 @@ buildtests_cxx: privatelibs_cxx \
   $(BINDIR)/$(CONFIG)/client_channel_stress_test \
   $(BINDIR)/$(CONFIG)/client_crash_test \
   $(BINDIR)/$(CONFIG)/client_crash_test_server \
+  $(BINDIR)/$(CONFIG)/client_interceptors_end2end_test \
   $(BINDIR)/$(CONFIG)/client_lb_end2end_test \
   $(BINDIR)/$(CONFIG)/codegen_test_full \
   $(BINDIR)/$(CONFIG)/codegen_test_minimal \
@@ -1727,6 +1728,7 @@ buildtests_cxx: privatelibs_cxx \
   $(BINDIR)/$(CONFIG)/server_crash_test \
   $(BINDIR)/$(CONFIG)/server_crash_test_client \
   $(BINDIR)/$(CONFIG)/server_early_return_test \
+  $(BINDIR)/$(CONFIG)/server_interceptors_end2end_test \
   $(BINDIR)/$(CONFIG)/server_request_call_test \
   $(BINDIR)/$(CONFIG)/shutdown_test \
   $(BINDIR)/$(CONFIG)/slice_hash_table_test \
@@ -1850,6 +1852,7 @@ buildtests_cxx: privatelibs_cxx \
   $(BINDIR)/$(CONFIG)/client_channel_stress_test \
   $(BINDIR)/$(CONFIG)/client_crash_test \
   $(BINDIR)/$(CONFIG)/client_crash_test_server \
+  $(BINDIR)/$(CONFIG)/client_interceptors_end2end_test \
   $(BINDIR)/$(CONFIG)/client_lb_end2end_test \
   $(BINDIR)/$(CONFIG)/codegen_test_full \
   $(BINDIR)/$(CONFIG)/codegen_test_minimal \
@@ -1908,6 +1911,7 @@ buildtests_cxx: privatelibs_cxx \
   $(BINDIR)/$(CONFIG)/server_crash_test \
   $(BINDIR)/$(CONFIG)/server_crash_test_client \
   $(BINDIR)/$(CONFIG)/server_early_return_test \
+  $(BINDIR)/$(CONFIG)/server_interceptors_end2end_test \
   $(BINDIR)/$(CONFIG)/server_request_call_test \
   $(BINDIR)/$(CONFIG)/shutdown_test \
   $(BINDIR)/$(CONFIG)/slice_hash_table_test \
@@ -2058,10 +2062,10 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/grpc_security_connector_test || ( echo test grpc_security_connector_test failed ; exit 1 )
 	$(E) "[RUN]     Testing grpc_ssl_credentials_test"
 	$(Q) $(BINDIR)/$(CONFIG)/grpc_ssl_credentials_test || ( echo test grpc_ssl_credentials_test failed ; exit 1 )
-	$(E) "[RUN]     Testing handshake_client"
-	$(Q) $(BINDIR)/$(CONFIG)/handshake_client || ( echo test handshake_client failed ; exit 1 )
-	$(E) "[RUN]     Testing handshake_server"
-	$(Q) $(BINDIR)/$(CONFIG)/handshake_server || ( echo test handshake_server failed ; exit 1 )
+	$(E) "[RUN]     Testing handshake_client_ssl"
+	$(Q) $(BINDIR)/$(CONFIG)/handshake_client_ssl || ( echo test handshake_client_ssl failed ; exit 1 )
+	$(E) "[RUN]     Testing handshake_server_ssl"
+	$(Q) $(BINDIR)/$(CONFIG)/handshake_server_ssl || ( echo test handshake_server_ssl failed ; exit 1 )
 	$(E) "[RUN]     Testing handshake_server_with_readahead_handshaker"
 	$(Q) $(BINDIR)/$(CONFIG)/handshake_server_with_readahead_handshaker || ( echo test handshake_server_with_readahead_handshaker failed ; exit 1 )
 	$(E) "[RUN]     Testing handshake_verify_peer_options"
@@ -2096,8 +2100,8 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/lame_client_test || ( echo test lame_client_test failed ; exit 1 )
 	$(E) "[RUN]     Testing load_file_test"
 	$(Q) $(BINDIR)/$(CONFIG)/load_file_test || ( echo test load_file_test failed ; exit 1 )
-	$(E) "[RUN]     Testing memory_profile_test"
-	$(Q) $(BINDIR)/$(CONFIG)/memory_profile_test || ( echo test memory_profile_test failed ; exit 1 )
+	$(E) "[RUN]     Testing memory_usage_test"
+	$(Q) $(BINDIR)/$(CONFIG)/memory_usage_test || ( echo test memory_usage_test failed ; exit 1 )
 	$(E) "[RUN]     Testing message_compress_test"
 	$(Q) $(BINDIR)/$(CONFIG)/message_compress_test || ( echo test message_compress_test failed ; exit 1 )
 	$(E) "[RUN]     Testing minimal_stack_is_minimal_test"
@@ -2308,6 +2312,8 @@ test_cxx: buildtests_cxx
 	$(Q) $(BINDIR)/$(CONFIG)/client_channel_stress_test || ( echo test client_channel_stress_test failed ; exit 1 )
 	$(E) "[RUN]     Testing client_crash_test"
 	$(Q) $(BINDIR)/$(CONFIG)/client_crash_test || ( echo test client_crash_test failed ; exit 1 )
+	$(E) "[RUN]     Testing client_interceptors_end2end_test"
+	$(Q) $(BINDIR)/$(CONFIG)/client_interceptors_end2end_test || ( echo test client_interceptors_end2end_test failed ; exit 1 )
 	$(E) "[RUN]     Testing client_lb_end2end_test"
 	$(Q) $(BINDIR)/$(CONFIG)/client_lb_end2end_test || ( echo test client_lb_end2end_test failed ; exit 1 )
 	$(E) "[RUN]     Testing codegen_test_full"
@@ -2398,6 +2404,8 @@ test_cxx: buildtests_cxx
 	$(Q) $(BINDIR)/$(CONFIG)/server_crash_test || ( echo test server_crash_test failed ; exit 1 )
 	$(E) "[RUN]     Testing server_early_return_test"
 	$(Q) $(BINDIR)/$(CONFIG)/server_early_return_test || ( echo test server_early_return_test failed ; exit 1 )
+	$(E) "[RUN]     Testing server_interceptors_end2end_test"
+	$(Q) $(BINDIR)/$(CONFIG)/server_interceptors_end2end_test || ( echo test server_interceptors_end2end_test failed ; exit 1 )
 	$(E) "[RUN]     Testing server_request_call_test"
 	$(Q) $(BINDIR)/$(CONFIG)/server_request_call_test || ( echo test server_request_call_test failed ; exit 1 )
 	$(E) "[RUN]     Testing shutdown_test"
@@ -3592,6 +3600,7 @@ LIBGRPC_SRC = \
     src/core/lib/transport/timeout_encoding.cc \
     src/core/lib/transport/transport.cc \
     src/core/lib/transport/transport_op_string.cc \
+    src/core/lib/uri/uri_parser.cc \
     src/core/lib/debug/trace.cc \
     src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc \
     src/core/ext/transport/chttp2/transport/bin_decoder.cc \
@@ -3638,11 +3647,14 @@ LIBGRPC_SRC = \
     src/core/lib/security/credentials/oauth2/oauth2_credentials.cc \
     src/core/lib/security/credentials/plugin/plugin_credentials.cc \
     src/core/lib/security/credentials/ssl/ssl_credentials.cc \
-    src/core/lib/security/security_connector/alts_security_connector.cc \
+    src/core/lib/security/security_connector/alts/alts_security_connector.cc \
+    src/core/lib/security/security_connector/fake/fake_security_connector.cc \
     src/core/lib/security/security_connector/load_system_roots_fallback.cc \
     src/core/lib/security/security_connector/load_system_roots_linux.cc \
-    src/core/lib/security/security_connector/local_security_connector.cc \
+    src/core/lib/security/security_connector/local/local_security_connector.cc \
     src/core/lib/security/security_connector/security_connector.cc \
+    src/core/lib/security/security_connector/ssl/ssl_security_connector.cc \
+    src/core/lib/security/security_connector/ssl_utils.cc \
     src/core/lib/security/transport/client_auth_filter.cc \
     src/core/lib/security/transport/secure_endpoint.cc \
     src/core/lib/security/transport/security_handshaker.cc \
@@ -3697,6 +3709,7 @@ LIBGRPC_SRC = \
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/connector.cc \
+    src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
@@ -3711,8 +3724,8 @@ LIBGRPC_SRC = \
     src/core/ext/filters/client_channel/retry_throttle.cc \
     src/core/ext/filters/client_channel/subchannel.cc \
     src/core/ext/filters/client_channel/subchannel_index.cc \
-    src/core/ext/filters/client_channel/uri_parser.cc \
     src/core/ext/filters/deadline/deadline_filter.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
     src/core/tsi/alts_transport_security.cc \
     src/core/tsi/fake_transport_security.cc \
     src/core/tsi/local_transport_security.cc \
@@ -3732,10 +3745,14 @@ LIBGRPC_SRC = \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc \
+    src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c \
-    src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc \
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
@@ -3998,6 +4015,7 @@ LIBGRPC_CRONET_SRC = \
     src/core/lib/transport/timeout_encoding.cc \
     src/core/lib/transport/transport.cc \
     src/core/lib/transport/transport_op_string.cc \
+    src/core/lib/uri/uri_parser.cc \
     src/core/lib/debug/trace.cc \
     src/core/ext/transport/cronet/client/secure/cronet_channel_create.cc \
     src/core/ext/transport/cronet/transport/cronet_api_dummy.cc \
@@ -4037,6 +4055,7 @@ LIBGRPC_CRONET_SRC = \
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/connector.cc \
+    src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
@@ -4051,8 +4070,11 @@ LIBGRPC_CRONET_SRC = \
     src/core/ext/filters/client_channel/retry_throttle.cc \
     src/core/ext/filters/client_channel/subchannel.cc \
     src/core/ext/filters/client_channel/subchannel_index.cc \
-    src/core/ext/filters/client_channel/uri_parser.cc \
     src/core/ext/filters/deadline/deadline_filter.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
+    third_party/nanopb/pb_common.c \
+    third_party/nanopb/pb_decode.c \
+    third_party/nanopb/pb_encode.c \
     src/core/lib/http/httpcli_security_connector.cc \
     src/core/lib/security/context/security_context.cc \
     src/core/lib/security/credentials/alts/alts_credentials.cc \
@@ -4070,11 +4092,14 @@ LIBGRPC_CRONET_SRC = \
     src/core/lib/security/credentials/oauth2/oauth2_credentials.cc \
     src/core/lib/security/credentials/plugin/plugin_credentials.cc \
     src/core/lib/security/credentials/ssl/ssl_credentials.cc \
-    src/core/lib/security/security_connector/alts_security_connector.cc \
+    src/core/lib/security/security_connector/alts/alts_security_connector.cc \
+    src/core/lib/security/security_connector/fake/fake_security_connector.cc \
     src/core/lib/security/security_connector/load_system_roots_fallback.cc \
     src/core/lib/security/security_connector/load_system_roots_linux.cc \
-    src/core/lib/security/security_connector/local_security_connector.cc \
+    src/core/lib/security/security_connector/local/local_security_connector.cc \
     src/core/lib/security/security_connector/security_connector.cc \
+    src/core/lib/security/security_connector/ssl/ssl_security_connector.cc \
+    src/core/lib/security/security_connector/ssl_utils.cc \
     src/core/lib/security/transport/client_auth_filter.cc \
     src/core/lib/security/transport/secure_endpoint.cc \
     src/core/lib/security/transport/security_handshaker.cc \
@@ -4114,9 +4139,6 @@ LIBGRPC_CRONET_SRC = \
     src/core/tsi/alts/handshaker/altscontext.pb.c \
     src/core/tsi/alts/handshaker/handshaker.pb.c \
     src/core/tsi/alts/handshaker/transport_security_common.pb.c \
-    third_party/nanopb/pb_common.c \
-    third_party/nanopb/pb_decode.c \
-    third_party/nanopb/pb_encode.c \
     src/core/tsi/transport_security.cc \
     src/core/ext/transport/chttp2/client/insecure/channel_create.cc \
     src/core/ext/transport/chttp2/client/insecure/channel_create_posix.cc \
@@ -4389,6 +4411,7 @@ LIBGRPC_TEST_UTIL_SRC = \
     src/core/lib/transport/timeout_encoding.cc \
     src/core/lib/transport/transport.cc \
     src/core/lib/transport/transport_op_string.cc \
+    src/core/lib/uri/uri_parser.cc \
     src/core/lib/debug/trace.cc \
     src/core/ext/filters/client_channel/backup_poller.cc \
     src/core/ext/filters/client_channel/channel_connectivity.cc \
@@ -4397,6 +4420,7 @@ LIBGRPC_TEST_UTIL_SRC = \
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/connector.cc \
+    src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
@@ -4411,8 +4435,11 @@ LIBGRPC_TEST_UTIL_SRC = \
     src/core/ext/filters/client_channel/retry_throttle.cc \
     src/core/ext/filters/client_channel/subchannel.cc \
     src/core/ext/filters/client_channel/subchannel_index.cc \
-    src/core/ext/filters/client_channel/uri_parser.cc \
     src/core/ext/filters/deadline/deadline_filter.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
+    third_party/nanopb/pb_common.c \
+    third_party/nanopb/pb_decode.c \
+    third_party/nanopb/pb_encode.c \
     src/core/ext/transport/chttp2/transport/bin_decoder.cc \
     src/core/ext/transport/chttp2/transport/bin_encoder.cc \
     src/core/ext/transport/chttp2/transport/chttp2_plugin.cc \
@@ -4689,6 +4716,7 @@ LIBGRPC_TEST_UTIL_UNSECURE_SRC = \
     src/core/lib/transport/timeout_encoding.cc \
     src/core/lib/transport/transport.cc \
     src/core/lib/transport/transport_op_string.cc \
+    src/core/lib/uri/uri_parser.cc \
     src/core/lib/debug/trace.cc \
     src/core/ext/filters/client_channel/backup_poller.cc \
     src/core/ext/filters/client_channel/channel_connectivity.cc \
@@ -4697,6 +4725,7 @@ LIBGRPC_TEST_UTIL_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/connector.cc \
+    src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
@@ -4711,8 +4740,11 @@ LIBGRPC_TEST_UTIL_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/retry_throttle.cc \
     src/core/ext/filters/client_channel/subchannel.cc \
     src/core/ext/filters/client_channel/subchannel_index.cc \
-    src/core/ext/filters/client_channel/uri_parser.cc \
     src/core/ext/filters/deadline/deadline_filter.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
+    third_party/nanopb/pb_common.c \
+    third_party/nanopb/pb_decode.c \
+    third_party/nanopb/pb_encode.c \
     src/core/ext/transport/chttp2/transport/bin_decoder.cc \
     src/core/ext/transport/chttp2/transport/bin_encoder.cc \
     src/core/ext/transport/chttp2/transport/chttp2_plugin.cc \
@@ -4955,6 +4987,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/lib/transport/timeout_encoding.cc \
     src/core/lib/transport/transport.cc \
     src/core/lib/transport/transport_op_string.cc \
+    src/core/lib/uri/uri_parser.cc \
     src/core/lib/debug/trace.cc \
     src/core/ext/transport/chttp2/server/insecure/server_chttp2.cc \
     src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.cc \
@@ -4997,6 +5030,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/connector.cc \
+    src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
@@ -5011,8 +5045,11 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/retry_throttle.cc \
     src/core/ext/filters/client_channel/subchannel.cc \
     src/core/ext/filters/client_channel/subchannel_index.cc \
-    src/core/ext/filters/client_channel/uri_parser.cc \
     src/core/ext/filters/deadline/deadline_filter.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
+    third_party/nanopb/pb_common.c \
+    third_party/nanopb/pb_decode.c \
+    third_party/nanopb/pb_encode.c \
     src/core/ext/transport/inproc/inproc_plugin.cc \
     src/core/ext/transport/inproc/inproc_transport.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
@@ -5034,9 +5071,10 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c \
-    third_party/nanopb/pb_common.c \
-    third_party/nanopb/pb_decode.c \
-    third_party/nanopb/pb_encode.c \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc \
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
     src/core/ext/filters/census/grpc_context.cc \
@@ -5228,7 +5266,6 @@ LIBGRPC++_SRC = \
     src/cpp/server/create_default_thread_pool.cc \
     src/cpp/server/dynamic_thread_pool.cc \
     src/cpp/server/health/default_health_check_service.cc \
-    src/cpp/server/health/health.pb.c \
     src/cpp/server/health/health_check_service.cc \
     src/cpp/server/health/health_check_service_server_builder_option.cc \
     src/cpp/server/server_builder.cc \
@@ -5241,6 +5278,10 @@ LIBGRPC++_SRC = \
     src/cpp/util/status.cc \
     src/cpp/util/string_ref.cc \
     src/cpp/util/time_cc.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
+    third_party/nanopb/pb_common.c \
+    third_party/nanopb/pb_decode.c \
+    third_party/nanopb/pb_encode.c \
     src/cpp/codegen/codegen_init.cc \
 
 PUBLIC_HEADERS_CXX += \
@@ -5330,6 +5371,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/config.h \
     include/grpcpp/support/proto_buffer_reader.h \
     include/grpcpp/support/proto_buffer_writer.h \
+    include/grpcpp/support/server_callback.h \
     include/grpcpp/support/slice.h \
     include/grpcpp/support/status.h \
     include/grpcpp/support/status_code_enum.h \
@@ -5424,6 +5466,8 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
+    include/grpcpp/impl/codegen/call_op_set.h \
+    include/grpcpp/impl/codegen/call_op_set_interface.h \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
@@ -5436,14 +5480,18 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/core_codegen_interface.h \
     include/grpcpp/impl/codegen/create_auth_context.h \
     include/grpcpp/impl/codegen/grpc_library.h \
+    include/grpcpp/impl/codegen/intercepted_channel.h \
     include/grpcpp/impl/codegen/interceptor.h \
+    include/grpcpp/impl/codegen/interceptor_common.h \
     include/grpcpp/impl/codegen/metadata_map.h \
     include/grpcpp/impl/codegen/method_handler_impl.h \
     include/grpcpp/impl/codegen/rpc_method.h \
     include/grpcpp/impl/codegen/rpc_service_method.h \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
+    include/grpcpp/impl/codegen/server_callback.h \
     include/grpcpp/impl/codegen/server_context.h \
+    include/grpcpp/impl/codegen/server_interceptor.h \
     include/grpcpp/impl/codegen/server_interface.h \
     include/grpcpp/impl/codegen/service_type.h \
     include/grpcpp/impl/codegen/slice.h \
@@ -5599,7 +5647,6 @@ LIBGRPC++_CRONET_SRC = \
     src/cpp/server/create_default_thread_pool.cc \
     src/cpp/server/dynamic_thread_pool.cc \
     src/cpp/server/health/default_health_check_service.cc \
-    src/cpp/server/health/health.pb.c \
     src/cpp/server/health/health_check_service.cc \
     src/cpp/server/health/health_check_service_server_builder_option.cc \
     src/cpp/server/server_builder.cc \
@@ -5612,6 +5659,10 @@ LIBGRPC++_CRONET_SRC = \
     src/cpp/util/status.cc \
     src/cpp/util/string_ref.cc \
     src/cpp/util/time_cc.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
+    third_party/nanopb/pb_common.c \
+    third_party/nanopb/pb_decode.c \
+    third_party/nanopb/pb_encode.c \
     src/cpp/codegen/codegen_init.cc \
     src/core/ext/transport/chttp2/client/insecure/channel_create.cc \
     src/core/ext/transport/chttp2/client/insecure/channel_create_posix.cc \
@@ -5789,6 +5840,7 @@ LIBGRPC++_CRONET_SRC = \
     src/core/lib/transport/timeout_encoding.cc \
     src/core/lib/transport/transport.cc \
     src/core/lib/transport/transport_op_string.cc \
+    src/core/lib/uri/uri_parser.cc \
     src/core/lib/debug/trace.cc \
     src/core/ext/transport/chttp2/alpn/alpn.cc \
     src/core/ext/filters/http/client/http_client_filter.cc \
@@ -5802,6 +5854,7 @@ LIBGRPC++_CRONET_SRC = \
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/connector.cc \
+    src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
@@ -5816,7 +5869,6 @@ LIBGRPC++_CRONET_SRC = \
     src/core/ext/filters/client_channel/retry_throttle.cc \
     src/core/ext/filters/client_channel/subchannel.cc \
     src/core/ext/filters/client_channel/subchannel_index.cc \
-    src/core/ext/filters/client_channel/uri_parser.cc \
     src/core/ext/filters/deadline/deadline_filter.cc \
     src/core/ext/transport/chttp2/server/insecure/server_chttp2.cc \
     src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.cc \
@@ -5910,6 +5962,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/config.h \
     include/grpcpp/support/proto_buffer_reader.h \
     include/grpcpp/support/proto_buffer_writer.h \
+    include/grpcpp/support/server_callback.h \
     include/grpcpp/support/slice.h \
     include/grpcpp/support/status.h \
     include/grpcpp/support/status_code_enum.h \
@@ -6004,6 +6057,8 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
+    include/grpcpp/impl/codegen/call_op_set.h \
+    include/grpcpp/impl/codegen/call_op_set_interface.h \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
@@ -6016,14 +6071,18 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/core_codegen_interface.h \
     include/grpcpp/impl/codegen/create_auth_context.h \
     include/grpcpp/impl/codegen/grpc_library.h \
+    include/grpcpp/impl/codegen/intercepted_channel.h \
     include/grpcpp/impl/codegen/interceptor.h \
+    include/grpcpp/impl/codegen/interceptor_common.h \
     include/grpcpp/impl/codegen/metadata_map.h \
     include/grpcpp/impl/codegen/method_handler_impl.h \
     include/grpcpp/impl/codegen/rpc_method.h \
     include/grpcpp/impl/codegen/rpc_service_method.h \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
+    include/grpcpp/impl/codegen/server_callback.h \
     include/grpcpp/impl/codegen/server_context.h \
+    include/grpcpp/impl/codegen/server_interceptor.h \
     include/grpcpp/impl/codegen/server_interface.h \
     include/grpcpp/impl/codegen/service_type.h \
     include/grpcpp/impl/codegen/slice.h \
@@ -6398,6 +6457,8 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
+    include/grpcpp/impl/codegen/call_op_set.h \
+    include/grpcpp/impl/codegen/call_op_set_interface.h \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
@@ -6410,14 +6471,18 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/core_codegen_interface.h \
     include/grpcpp/impl/codegen/create_auth_context.h \
     include/grpcpp/impl/codegen/grpc_library.h \
+    include/grpcpp/impl/codegen/intercepted_channel.h \
     include/grpcpp/impl/codegen/interceptor.h \
+    include/grpcpp/impl/codegen/interceptor_common.h \
     include/grpcpp/impl/codegen/metadata_map.h \
     include/grpcpp/impl/codegen/method_handler_impl.h \
     include/grpcpp/impl/codegen/rpc_method.h \
     include/grpcpp/impl/codegen/rpc_service_method.h \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
+    include/grpcpp/impl/codegen/server_callback.h \
     include/grpcpp/impl/codegen/server_context.h \
+    include/grpcpp/impl/codegen/server_interceptor.h \
     include/grpcpp/impl/codegen/server_interface.h \
     include/grpcpp/impl/codegen/service_type.h \
     include/grpcpp/impl/codegen/slice.h \
@@ -6556,6 +6621,8 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
+    include/grpcpp/impl/codegen/call_op_set.h \
+    include/grpcpp/impl/codegen/call_op_set_interface.h \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
@@ -6568,14 +6635,18 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/core_codegen_interface.h \
     include/grpcpp/impl/codegen/create_auth_context.h \
     include/grpcpp/impl/codegen/grpc_library.h \
+    include/grpcpp/impl/codegen/intercepted_channel.h \
     include/grpcpp/impl/codegen/interceptor.h \
+    include/grpcpp/impl/codegen/interceptor_common.h \
     include/grpcpp/impl/codegen/metadata_map.h \
     include/grpcpp/impl/codegen/method_handler_impl.h \
     include/grpcpp/impl/codegen/rpc_method.h \
     include/grpcpp/impl/codegen/rpc_service_method.h \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
+    include/grpcpp/impl/codegen/server_callback.h \
     include/grpcpp/impl/codegen/server_context.h \
+    include/grpcpp/impl/codegen/server_interceptor.h \
     include/grpcpp/impl/codegen/server_interface.h \
     include/grpcpp/impl/codegen/service_type.h \
     include/grpcpp/impl/codegen/slice.h \
@@ -6687,7 +6758,6 @@ LIBGRPC++_UNSECURE_SRC = \
     src/cpp/server/create_default_thread_pool.cc \
     src/cpp/server/dynamic_thread_pool.cc \
     src/cpp/server/health/default_health_check_service.cc \
-    src/cpp/server/health/health.pb.c \
     src/cpp/server/health/health_check_service.cc \
     src/cpp/server/health/health_check_service_server_builder_option.cc \
     src/cpp/server/server_builder.cc \
@@ -6700,6 +6770,10 @@ LIBGRPC++_UNSECURE_SRC = \
     src/cpp/util/status.cc \
     src/cpp/util/string_ref.cc \
     src/cpp/util/time_cc.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
+    third_party/nanopb/pb_common.c \
+    third_party/nanopb/pb_decode.c \
+    third_party/nanopb/pb_encode.c \
     src/cpp/codegen/codegen_init.cc \
 
 PUBLIC_HEADERS_CXX += \
@@ -6789,6 +6863,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/config.h \
     include/grpcpp/support/proto_buffer_reader.h \
     include/grpcpp/support/proto_buffer_writer.h \
+    include/grpcpp/support/server_callback.h \
     include/grpcpp/support/slice.h \
     include/grpcpp/support/status.h \
     include/grpcpp/support/status_code_enum.h \
@@ -6883,6 +6958,8 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
+    include/grpcpp/impl/codegen/call_op_set.h \
+    include/grpcpp/impl/codegen/call_op_set_interface.h \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
@@ -6895,14 +6972,18 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/core_codegen_interface.h \
     include/grpcpp/impl/codegen/create_auth_context.h \
     include/grpcpp/impl/codegen/grpc_library.h \
+    include/grpcpp/impl/codegen/intercepted_channel.h \
     include/grpcpp/impl/codegen/interceptor.h \
+    include/grpcpp/impl/codegen/interceptor_common.h \
     include/grpcpp/impl/codegen/metadata_map.h \
     include/grpcpp/impl/codegen/method_handler_impl.h \
     include/grpcpp/impl/codegen/rpc_method.h \
     include/grpcpp/impl/codegen/rpc_service_method.h \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
+    include/grpcpp/impl/codegen/server_callback.h \
     include/grpcpp/impl/codegen/server_context.h \
+    include/grpcpp/impl/codegen/server_interceptor.h \
     include/grpcpp/impl/codegen/server_interface.h \
     include/grpcpp/impl/codegen/service_type.h \
     include/grpcpp/impl/codegen/slice.h \
@@ -12670,57 +12751,57 @@ endif
 endif
 
 
-HANDSHAKE_CLIENT_SRC = \
+HANDSHAKE_CLIENT_SSL_SRC = \
     test/core/handshake/client_ssl.cc \
 
-HANDSHAKE_CLIENT_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(HANDSHAKE_CLIENT_SRC))))
+HANDSHAKE_CLIENT_SSL_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(HANDSHAKE_CLIENT_SSL_SRC))))
 ifeq ($(NO_SECURE),true)
 
 # You can't build secure targets if you don't have OpenSSL.
 
-$(BINDIR)/$(CONFIG)/handshake_client: openssl_dep_error
+$(BINDIR)/$(CONFIG)/handshake_client_ssl: openssl_dep_error
 
 else
 
 
 
-$(BINDIR)/$(CONFIG)/handshake_client: $(HANDSHAKE_CLIENT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+$(BINDIR)/$(CONFIG)/handshake_client_ssl: $(HANDSHAKE_CLIENT_SSL_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(HANDSHAKE_CLIENT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/handshake_client
+	$(Q) $(LD) $(LDFLAGS) $(HANDSHAKE_CLIENT_SSL_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/handshake_client_ssl
 
 endif
 
 $(OBJDIR)/$(CONFIG)/test/core/handshake/client_ssl.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
-deps_handshake_client: $(HANDSHAKE_CLIENT_OBJS:.o=.dep)
+deps_handshake_client_ssl: $(HANDSHAKE_CLIENT_SSL_OBJS:.o=.dep)
 
 ifneq ($(NO_SECURE),true)
 ifneq ($(NO_DEPS),true)
--include $(HANDSHAKE_CLIENT_OBJS:.o=.dep)
+-include $(HANDSHAKE_CLIENT_SSL_OBJS:.o=.dep)
 endif
 endif
 
 
-HANDSHAKE_SERVER_SRC = \
+HANDSHAKE_SERVER_SSL_SRC = \
     test/core/handshake/server_ssl.cc \
     test/core/handshake/server_ssl_common.cc \
 
-HANDSHAKE_SERVER_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(HANDSHAKE_SERVER_SRC))))
+HANDSHAKE_SERVER_SSL_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(HANDSHAKE_SERVER_SSL_SRC))))
 ifeq ($(NO_SECURE),true)
 
 # You can't build secure targets if you don't have OpenSSL.
 
-$(BINDIR)/$(CONFIG)/handshake_server: openssl_dep_error
+$(BINDIR)/$(CONFIG)/handshake_server_ssl: openssl_dep_error
 
 else
 
 
 
-$(BINDIR)/$(CONFIG)/handshake_server: $(HANDSHAKE_SERVER_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+$(BINDIR)/$(CONFIG)/handshake_server_ssl: $(HANDSHAKE_SERVER_SSL_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(HANDSHAKE_SERVER_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/handshake_server
+	$(Q) $(LD) $(LDFLAGS) $(HANDSHAKE_SERVER_SSL_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/handshake_server_ssl
 
 endif
 
@@ -12728,11 +12809,11 @@ $(OBJDIR)/$(CONFIG)/test/core/handshake/server_ssl.o:  $(LIBDIR)/$(CONFIG)/libgr
 
 $(OBJDIR)/$(CONFIG)/test/core/handshake/server_ssl_common.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
-deps_handshake_server: $(HANDSHAKE_SERVER_OBJS:.o=.dep)
+deps_handshake_server_ssl: $(HANDSHAKE_SERVER_SSL_OBJS:.o=.dep)
 
 ifneq ($(NO_SECURE),true)
 ifneq ($(NO_DEPS),true)
--include $(HANDSHAKE_SERVER_OBJS:.o=.dep)
+-include $(HANDSHAKE_SERVER_SSL_OBJS:.o=.dep)
 endif
 endif
 
@@ -13476,98 +13557,98 @@ endif
 endif
 
 
-MEMORY_PROFILE_CLIENT_SRC = \
+MEMORY_USAGE_CLIENT_SRC = \
     test/core/memory_usage/client.cc \
 
-MEMORY_PROFILE_CLIENT_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(MEMORY_PROFILE_CLIENT_SRC))))
+MEMORY_USAGE_CLIENT_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(MEMORY_USAGE_CLIENT_SRC))))
 ifeq ($(NO_SECURE),true)
 
 # You can't build secure targets if you don't have OpenSSL.
 
-$(BINDIR)/$(CONFIG)/memory_profile_client: openssl_dep_error
+$(BINDIR)/$(CONFIG)/memory_usage_client: openssl_dep_error
 
 else
 
 
 
-$(BINDIR)/$(CONFIG)/memory_profile_client: $(MEMORY_PROFILE_CLIENT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+$(BINDIR)/$(CONFIG)/memory_usage_client: $(MEMORY_USAGE_CLIENT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(MEMORY_PROFILE_CLIENT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/memory_profile_client
+	$(Q) $(LD) $(LDFLAGS) $(MEMORY_USAGE_CLIENT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/memory_usage_client
 
 endif
 
 $(OBJDIR)/$(CONFIG)/test/core/memory_usage/client.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
-deps_memory_profile_client: $(MEMORY_PROFILE_CLIENT_OBJS:.o=.dep)
+deps_memory_usage_client: $(MEMORY_USAGE_CLIENT_OBJS:.o=.dep)
 
 ifneq ($(NO_SECURE),true)
 ifneq ($(NO_DEPS),true)
--include $(MEMORY_PROFILE_CLIENT_OBJS:.o=.dep)
+-include $(MEMORY_USAGE_CLIENT_OBJS:.o=.dep)
 endif
 endif
 
 
-MEMORY_PROFILE_SERVER_SRC = \
+MEMORY_USAGE_SERVER_SRC = \
     test/core/memory_usage/server.cc \
 
-MEMORY_PROFILE_SERVER_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(MEMORY_PROFILE_SERVER_SRC))))
+MEMORY_USAGE_SERVER_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(MEMORY_USAGE_SERVER_SRC))))
 ifeq ($(NO_SECURE),true)
 
 # You can't build secure targets if you don't have OpenSSL.
 
-$(BINDIR)/$(CONFIG)/memory_profile_server: openssl_dep_error
+$(BINDIR)/$(CONFIG)/memory_usage_server: openssl_dep_error
 
 else
 
 
 
-$(BINDIR)/$(CONFIG)/memory_profile_server: $(MEMORY_PROFILE_SERVER_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+$(BINDIR)/$(CONFIG)/memory_usage_server: $(MEMORY_USAGE_SERVER_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(MEMORY_PROFILE_SERVER_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/memory_profile_server
+	$(Q) $(LD) $(LDFLAGS) $(MEMORY_USAGE_SERVER_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/memory_usage_server
 
 endif
 
 $(OBJDIR)/$(CONFIG)/test/core/memory_usage/server.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
-deps_memory_profile_server: $(MEMORY_PROFILE_SERVER_OBJS:.o=.dep)
+deps_memory_usage_server: $(MEMORY_USAGE_SERVER_OBJS:.o=.dep)
 
 ifneq ($(NO_SECURE),true)
 ifneq ($(NO_DEPS),true)
--include $(MEMORY_PROFILE_SERVER_OBJS:.o=.dep)
+-include $(MEMORY_USAGE_SERVER_OBJS:.o=.dep)
 endif
 endif
 
 
-MEMORY_PROFILE_TEST_SRC = \
+MEMORY_USAGE_TEST_SRC = \
     test/core/memory_usage/memory_usage_test.cc \
 
-MEMORY_PROFILE_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(MEMORY_PROFILE_TEST_SRC))))
+MEMORY_USAGE_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(MEMORY_USAGE_TEST_SRC))))
 ifeq ($(NO_SECURE),true)
 
 # You can't build secure targets if you don't have OpenSSL.
 
-$(BINDIR)/$(CONFIG)/memory_profile_test: openssl_dep_error
+$(BINDIR)/$(CONFIG)/memory_usage_test: openssl_dep_error
 
 else
 
 
 
-$(BINDIR)/$(CONFIG)/memory_profile_test: $(MEMORY_PROFILE_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+$(BINDIR)/$(CONFIG)/memory_usage_test: $(MEMORY_USAGE_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(MEMORY_PROFILE_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/memory_profile_test
+	$(Q) $(LD) $(LDFLAGS) $(MEMORY_USAGE_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/memory_usage_test
 
 endif
 
 $(OBJDIR)/$(CONFIG)/test/core/memory_usage/memory_usage_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
-deps_memory_profile_test: $(MEMORY_PROFILE_TEST_OBJS:.o=.dep)
+deps_memory_usage_test: $(MEMORY_USAGE_TEST_OBJS:.o=.dep)
 
 ifneq ($(NO_SECURE),true)
 ifneq ($(NO_DEPS),true)
--include $(MEMORY_PROFILE_TEST_OBJS:.o=.dep)
+-include $(MEMORY_USAGE_TEST_OBJS:.o=.dep)
 endif
 endif
 
@@ -17241,6 +17322,49 @@ endif
 endif
 
 
+CLIENT_INTERCEPTORS_END2END_TEST_SRC = \
+    test/cpp/end2end/client_interceptors_end2end_test.cc \
+
+CLIENT_INTERCEPTORS_END2END_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(CLIENT_INTERCEPTORS_END2END_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/client_interceptors_end2end_test: openssl_dep_error
+
+else
+
+
+
+
+ifeq ($(NO_PROTOBUF),true)
+
+# You can't build the protoc plugins or protobuf-enabled targets if you don't have protobuf 3.5.0+.
+
+$(BINDIR)/$(CONFIG)/client_interceptors_end2end_test: protobuf_dep_error
+
+else
+
+$(BINDIR)/$(CONFIG)/client_interceptors_end2end_test: $(PROTOBUF_DEP) $(CLIENT_INTERCEPTORS_END2END_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LDXX) $(LDFLAGS) $(CLIENT_INTERCEPTORS_END2END_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) $(LDLIBS_SECURE) $(GTEST_LIB) -o $(BINDIR)/$(CONFIG)/client_interceptors_end2end_test
+
+endif
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/cpp/end2end/client_interceptors_end2end_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
+deps_client_interceptors_end2end_test: $(CLIENT_INTERCEPTORS_END2END_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(CLIENT_INTERCEPTORS_END2END_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 CLIENT_LB_END2END_TEST_SRC = \
     test/cpp/end2end/client_lb_end2end_test.cc \
 
@@ -20026,6 +20150,49 @@ endif
 endif
 
 
+SERVER_INTERCEPTORS_END2END_TEST_SRC = \
+    test/cpp/end2end/server_interceptors_end2end_test.cc \
+
+SERVER_INTERCEPTORS_END2END_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(SERVER_INTERCEPTORS_END2END_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/server_interceptors_end2end_test: openssl_dep_error
+
+else
+
+
+
+
+ifeq ($(NO_PROTOBUF),true)
+
+# You can't build the protoc plugins or protobuf-enabled targets if you don't have protobuf 3.5.0+.
+
+$(BINDIR)/$(CONFIG)/server_interceptors_end2end_test: protobuf_dep_error
+
+else
+
+$(BINDIR)/$(CONFIG)/server_interceptors_end2end_test: $(PROTOBUF_DEP) $(SERVER_INTERCEPTORS_END2END_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LDXX) $(LDFLAGS) $(SERVER_INTERCEPTORS_END2END_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) $(LDLIBS_SECURE) $(GTEST_LIB) -o $(BINDIR)/$(CONFIG)/server_interceptors_end2end_test
+
+endif
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/cpp/end2end/server_interceptors_end2end_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
+deps_server_interceptors_end2end_test: $(SERVER_INTERCEPTORS_END2END_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(SERVER_INTERCEPTORS_END2END_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 SERVER_REQUEST_CALL_TEST_SRC = \
     $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc \
     $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc \
@@ -23984,26 +24151,6 @@ ifneq ($(NO_DEPS),true)
 endif
 
 
-INPROC_NOSEC_TEST_SRC = \
-    test/core/end2end/fixtures/inproc.cc \
-
-INPROC_NOSEC_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(INPROC_NOSEC_TEST_SRC))))
-
-
-$(BINDIR)/$(CONFIG)/inproc_nosec_test: $(INPROC_NOSEC_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libend2end_nosec_tests.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util_unsecure.a $(LIBDIR)/$(CONFIG)/libgrpc_unsecure.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
-	$(E) "[LD]      Linking $@"
-	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(INPROC_NOSEC_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libend2end_nosec_tests.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util_unsecure.a $(LIBDIR)/$(CONFIG)/libgrpc_unsecure.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) -o $(BINDIR)/$(CONFIG)/inproc_nosec_test
-
-$(OBJDIR)/$(CONFIG)/test/core/end2end/fixtures/inproc.o:  $(LIBDIR)/$(CONFIG)/libend2end_nosec_tests.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util_unsecure.a $(LIBDIR)/$(CONFIG)/libgrpc_unsecure.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
-
-deps_inproc_nosec_test: $(INPROC_NOSEC_TEST_OBJS:.o=.dep)
-
-ifneq ($(NO_DEPS),true)
--include $(INPROC_NOSEC_TEST_OBJS:.o=.dep)
-endif
-
-
 RESOLVER_COMPONENT_TEST_UNSECURE_SRC = \
     test/cpp/naming/resolver_component_test.cc \
 
@@ -24804,6 +24951,7 @@ ifneq ($(OPENSSL_DEP),)
 # installing headers to their final destination on the drive. We need this
 # otherwise parallel compilation will fail if a source is compiled first.
 src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc: $(OPENSSL_DEP)
+src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc: $(OPENSSL_DEP)
 src/core/ext/transport/chttp2/client/secure/secure_channel_create.cc: $(OPENSSL_DEP)
 src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc: $(OPENSSL_DEP)
 src/core/ext/transport/cronet/client/secure/cronet_channel_create.cc: $(OPENSSL_DEP)
@@ -24833,11 +24981,14 @@ src/core/lib/security/credentials/local/local_credentials.cc: $(OPENSSL_DEP)
 src/core/lib/security/credentials/oauth2/oauth2_credentials.cc: $(OPENSSL_DEP)
 src/core/lib/security/credentials/plugin/plugin_credentials.cc: $(OPENSSL_DEP)
 src/core/lib/security/credentials/ssl/ssl_credentials.cc: $(OPENSSL_DEP)
-src/core/lib/security/security_connector/alts_security_connector.cc: $(OPENSSL_DEP)
+src/core/lib/security/security_connector/alts/alts_security_connector.cc: $(OPENSSL_DEP)
+src/core/lib/security/security_connector/fake/fake_security_connector.cc: $(OPENSSL_DEP)
 src/core/lib/security/security_connector/load_system_roots_fallback.cc: $(OPENSSL_DEP)
 src/core/lib/security/security_connector/load_system_roots_linux.cc: $(OPENSSL_DEP)
-src/core/lib/security/security_connector/local_security_connector.cc: $(OPENSSL_DEP)
+src/core/lib/security/security_connector/local/local_security_connector.cc: $(OPENSSL_DEP)
 src/core/lib/security/security_connector/security_connector.cc: $(OPENSSL_DEP)
+src/core/lib/security/security_connector/ssl/ssl_security_connector.cc: $(OPENSSL_DEP)
+src/core/lib/security/security_connector/ssl_utils.cc: $(OPENSSL_DEP)
 src/core/lib/security/transport/client_auth_filter.cc: $(OPENSSL_DEP)
 src/core/lib/security/transport/secure_endpoint.cc: $(OPENSSL_DEP)
 src/core/lib/security/transport/security_handshaker.cc: $(OPENSSL_DEP)

bazel/grpc_deps.bzl

@@ -102,7 +102,7 @@ def grpc_deps():
         native.http_archive(
             name = "boringssl",
             # on the chromium-stable-with-bazel branch
-            url = "https://boringssl.googlesource.com/boringssl/+archive/dcd3e6e6ecddf059adb48fca45bc7346a108bdd9.tar.gz",
+            url = "https://boringssl.googlesource.com/boringssl/+archive/afc30d43eef92979b05776ec0963c9cede5fb80f.tar.gz",
         )
 
     if "com_github_madler_zlib" not in native.existing_rules():
@@ -169,12 +169,12 @@ def grpc_deps():
     if "com_github_bazelbuild_bazeltoolchains" not in native.existing_rules():
         native.http_archive(
             name = "com_github_bazelbuild_bazeltoolchains",
-            strip_prefix = "bazel-toolchains-cdea5b8675914d0a354d89f108de5d28e54e0edc",
+            strip_prefix = "bazel-toolchains-280edaa6f93623074513d2b426068de42e62ea4d",
             urls = [
-                "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/cdea5b8675914d0a354d89f108de5d28e54e0edc.tar.gz",
-                "https://github.com/bazelbuild/bazel-toolchains/archive/cdea5b8675914d0a354d89f108de5d28e54e0edc.tar.gz",
+                "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/280edaa6f93623074513d2b426068de42e62ea4d.tar.gz",
+                "https://github.com/bazelbuild/bazel-toolchains/archive/280edaa6f93623074513d2b426068de42e62ea4d.tar.gz",
             ],
-            sha256 = "cefb6ccf86ca592baaa029bcef04148593c0efe8f734542f10293ea58f170715",
+            sha256 = "50c9df51f80cdf9ff8f2bc27620c155526b9ba67be95e8a686f32ff8898a06e2",
         )
 
     if "io_opencensus_cpp" not in native.existing_rules():

build.yaml

@@ -382,6 +382,7 @@ filegroups:
   - src/core/lib/transport/timeout_encoding.cc
   - src/core/lib/transport/transport.cc
   - src/core/lib/transport/transport_op_string.cc
+  - src/core/lib/uri/uri_parser.cc
   deps:
   - gpr
   filegroups:
@@ -538,6 +539,7 @@ filegroups:
   - src/core/lib/transport/timeout_encoding.h
   - src/core/lib/transport/transport.h
   - src/core/lib/transport/transport_impl.h
+  - src/core/lib/uri/uri_parser.h
   deps:
   - gpr
   uses:
@@ -572,6 +574,7 @@ filegroups:
   - src/core/ext/filters/client_channel/client_channel_channelz.h
   - src/core/ext/filters/client_channel/client_channel_factory.h
   - src/core/ext/filters/client_channel/connector.h
+  - src/core/ext/filters/client_channel/health/health_check_client.h
   - src/core/ext/filters/client_channel/http_connect_handshaker.h
   - src/core/ext/filters/client_channel/http_proxy.h
   - src/core/ext/filters/client_channel/lb_policy.h
@@ -587,7 +590,6 @@ filegroups:
   - src/core/ext/filters/client_channel/retry_throttle.h
   - src/core/ext/filters/client_channel/subchannel.h
   - src/core/ext/filters/client_channel/subchannel_index.h
-  - src/core/ext/filters/client_channel/uri_parser.h
   src:
   - src/core/ext/filters/client_channel/backup_poller.cc
   - src/core/ext/filters/client_channel/channel_connectivity.cc
@@ -596,6 +598,7 @@ filegroups:
   - src/core/ext/filters/client_channel/client_channel_factory.cc
   - src/core/ext/filters/client_channel/client_channel_plugin.cc
   - src/core/ext/filters/client_channel/connector.cc
+  - src/core/ext/filters/client_channel/health/health_check_client.cc
   - src/core/ext/filters/client_channel/http_connect_handshaker.cc
   - src/core/ext/filters/client_channel/http_proxy.cc
   - src/core/ext/filters/client_channel/lb_policy.cc
@@ -610,11 +613,11 @@ filegroups:
   - src/core/ext/filters/client_channel/retry_throttle.cc
   - src/core/ext/filters/client_channel/subchannel.cc
   - src/core/ext/filters/client_channel/subchannel_index.cc
-  - src/core/ext/filters/client_channel/uri_parser.cc
   plugin: grpc_client_channel
   uses:
   - grpc_base
   - grpc_deadline_filter
+  - health_proto
 - name: grpc_codegen
   public_headers:
   - include/grpc/impl/codegen/byte_buffer.h
@@ -655,24 +658,19 @@ filegroups:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
   src:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
   plugin: grpc_lb_policy_grpclb
   uses:
   - grpc_base
   - grpc_client_channel
   - nanopb
   - grpc_resolver_fake
+  - grpclb_proto
 - name: grpc_lb_policy_grpclb_secure
   headers:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h
@@ -680,18 +678,12 @@ filegroups:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
   src:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c
-  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
   plugin: grpc_lb_policy_grpclb
   uses:
   - grpc_base
@@ -699,6 +691,7 @@ filegroups:
   - grpc_client_channel
   - nanopb
   - grpc_resolver_fake
+  - grpclb_proto
 - name: grpc_lb_policy_pick_first
   src:
   - src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
@@ -715,6 +708,43 @@ filegroups:
   - grpc_base
   - grpc_client_channel
   - grpc_lb_subchannel_list
+- name: grpc_lb_policy_xds
+  headers:
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h
+  src:
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc
+  plugin: grpc_lb_policy_xds
+  uses:
+  - grpc_base
+  - grpc_client_channel
+  - nanopb
+  - grpc_resolver_fake
+  - grpclb_proto
+- name: grpc_lb_policy_xds_secure
+  headers:
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h
+  src:
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc
+  plugin: grpc_lb_policy_xds
+  uses:
+  - grpc_base
+  - grpc_secure
+  - grpc_client_channel
+  - nanopb
+  - grpc_resolver_fake
+  - grpclb_proto
 - name: grpc_lb_subchannel_list
   headers:
   - src/core/ext/filters/client_channel/lb_policy/subchannel_list.h
@@ -782,6 +812,7 @@ filegroups:
   - include/grpc/grpc_security.h
   headers:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds.h
   - src/core/lib/security/context/security_context.h
   - src/core/lib/security/credentials/alts/alts_credentials.h
   - src/core/lib/security/credentials/composite/composite_credentials.h
@@ -796,11 +827,14 @@ filegroups:
   - src/core/lib/security/credentials/oauth2/oauth2_credentials.h
   - src/core/lib/security/credentials/plugin/plugin_credentials.h
   - src/core/lib/security/credentials/ssl/ssl_credentials.h
-  - src/core/lib/security/security_connector/alts_security_connector.h
+  - src/core/lib/security/security_connector/alts/alts_security_connector.h
+  - src/core/lib/security/security_connector/fake/fake_security_connector.h
   - src/core/lib/security/security_connector/load_system_roots.h
   - src/core/lib/security/security_connector/load_system_roots_linux.h
-  - src/core/lib/security/security_connector/local_security_connector.h
+  - src/core/lib/security/security_connector/local/local_security_connector.h
   - src/core/lib/security/security_connector/security_connector.h
+  - src/core/lib/security/security_connector/ssl/ssl_security_connector.h
+  - src/core/lib/security/security_connector/ssl_utils.h
   - src/core/lib/security/transport/auth_filters.h
   - src/core/lib/security/transport/secure_endpoint.h
   - src/core/lib/security/transport/security_handshaker.h
@@ -825,11 +859,14 @@ filegroups:
   - src/core/lib/security/credentials/oauth2/oauth2_credentials.cc
   - src/core/lib/security/credentials/plugin/plugin_credentials.cc
   - src/core/lib/security/credentials/ssl/ssl_credentials.cc
-  - src/core/lib/security/security_connector/alts_security_connector.cc
+  - src/core/lib/security/security_connector/alts/alts_security_connector.cc
+  - src/core/lib/security/security_connector/fake/fake_security_connector.cc
   - src/core/lib/security/security_connector/load_system_roots_fallback.cc
   - src/core/lib/security/security_connector/load_system_roots_linux.cc
-  - src/core/lib/security/security_connector/local_security_connector.cc
+  - src/core/lib/security/security_connector/local/local_security_connector.cc
   - src/core/lib/security/security_connector/security_connector.cc
+  - src/core/lib/security/security_connector/ssl/ssl_security_connector.cc
+  - src/core/lib/security/security_connector/ssl_utils.cc
   - src/core/lib/security/transport/client_auth_filter.cc
   - src/core/lib/security/transport/secure_endpoint.cc
   - src/core/lib/security/transport/security_handshaker.cc
@@ -1068,6 +1105,24 @@ filegroups:
   uses:
   - grpc_base
   - grpc_server_backward_compatibility
+- name: grpclb_proto
+  headers:
+  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h
+  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h
+  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
+  src:
+  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c
+  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c
+  - src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
+  uses:
+  - nanopb
+- name: health_proto
+  headers:
+  - src/core/ext/filters/client_channel/health/health.pb.h
+  src:
+  - src/core/ext/filters/client_channel/health/health.pb.c
+  uses:
+  - nanopb
 - name: nanopb
   src:
   - third_party/nanopb/pb_common.c
@@ -1167,6 +1222,8 @@ filegroups:
   - include/grpcpp/impl/codegen/byte_buffer.h
   - include/grpcpp/impl/codegen/call.h
   - include/grpcpp/impl/codegen/call_hook.h
+  - include/grpcpp/impl/codegen/call_op_set.h
+  - include/grpcpp/impl/codegen/call_op_set_interface.h
   - include/grpcpp/impl/codegen/callback_common.h
   - include/grpcpp/impl/codegen/channel_interface.h
   - include/grpcpp/impl/codegen/client_callback.h
@@ -1179,14 +1236,18 @@ filegroups:
   - include/grpcpp/impl/codegen/core_codegen_interface.h
   - include/grpcpp/impl/codegen/create_auth_context.h
   - include/grpcpp/impl/codegen/grpc_library.h
+  - include/grpcpp/impl/codegen/intercepted_channel.h
   - include/grpcpp/impl/codegen/interceptor.h
+  - include/grpcpp/impl/codegen/interceptor_common.h
   - include/grpcpp/impl/codegen/metadata_map.h
   - include/grpcpp/impl/codegen/method_handler_impl.h
   - include/grpcpp/impl/codegen/rpc_method.h
   - include/grpcpp/impl/codegen/rpc_service_method.h
   - include/grpcpp/impl/codegen/security/auth_context.h
   - include/grpcpp/impl/codegen/serialization_traits.h
+  - include/grpcpp/impl/codegen/server_callback.h
   - include/grpcpp/impl/codegen/server_context.h
+  - include/grpcpp/impl/codegen/server_interceptor.h
   - include/grpcpp/impl/codegen/server_interface.h
   - include/grpcpp/impl/codegen/service_type.h
   - include/grpcpp/impl/codegen/slice.h
@@ -1303,6 +1364,7 @@ filegroups:
   - include/grpcpp/support/config.h
   - include/grpcpp/support/proto_buffer_reader.h
   - include/grpcpp/support/proto_buffer_writer.h
+  - include/grpcpp/support/server_callback.h
   - include/grpcpp/support/slice.h
   - include/grpcpp/support/status.h
   - include/grpcpp/support/status_code_enum.h
@@ -1315,7 +1377,6 @@ filegroups:
   - src/cpp/common/channel_filter.h
   - src/cpp/server/dynamic_thread_pool.h
   - src/cpp/server/health/default_health_check_service.h
-  - src/cpp/server/health/health.pb.h
   - src/cpp/server/thread_pool_interface.h
   - src/cpp/thread_manager/thread_manager.h
   src:
@@ -1339,7 +1400,6 @@ filegroups:
   - src/cpp/server/create_default_thread_pool.cc
   - src/cpp/server/dynamic_thread_pool.cc
   - src/cpp/server/health/default_health_check_service.cc
-  - src/cpp/server/health/health.pb.c
   - src/cpp/server/health/health_check_service.cc
   - src/cpp/server/health/health_check_service_server_builder_option.cc
   - src/cpp/server/server_builder.cc
@@ -1358,6 +1418,7 @@ filegroups:
   - grpc_transport_inproc_headers
   - grpc++_codegen_base
   - nanopb_headers
+  - health_proto
 - name: grpc++_config_proto
   language: c++
   public_headers:
@@ -1463,6 +1524,7 @@ libs:
   - grpc_transport_chttp2_client_insecure
   - grpc_transport_inproc
   - grpc_lb_policy_grpclb_secure
+  - grpc_lb_policy_xds_secure
   - grpc_lb_policy_pick_first
   - grpc_lb_policy_round_robin
   - grpc_resolver_dns_ares
@@ -1542,6 +1604,7 @@ libs:
   - grpc_resolver_sockaddr
   - grpc_resolver_fake
   - grpc_lb_policy_grpclb
+  - grpc_lb_policy_xds
   - grpc_lb_policy_pick_first
   - grpc_lb_policy_round_robin
   - census
@@ -2786,7 +2849,7 @@ targets:
   filegroups:
   - cmdline
   uses_polling: false
-- name: handshake_client
+- name: handshake_client_ssl
   build: test
   language: c
   src:
@@ -2801,7 +2864,7 @@ targets:
   platforms:
   - linux
   secure: true
-- name: handshake_server
+- name: handshake_server_ssl
   build: test
   language: c
   headers:
@@ -3100,7 +3163,7 @@ targets:
   - mac
   - linux
   - posix
-- name: memory_profile_client
+- name: memory_usage_client
   build: test
   run: false
   language: c
@@ -3112,7 +3175,7 @@ targets:
   - gpr_test_util
   - gpr
   uses_polling: false
-- name: memory_profile_server
+- name: memory_usage_server
   build: test
   run: false
   language: c
@@ -3123,7 +3186,7 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
-- name: memory_profile_test
+- name: memory_usage_test
   cpu_cost: 1.5
   build: test
   language: c
@@ -4467,6 +4530,22 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
+- name: client_interceptors_end2end_test
+  gtest: true
+  cpu_cost: 0.5
+  build: test
+  language: c++
+  headers:
+  - test/cpp/end2end/interceptors_util.h
+  src:
+  - test/cpp/end2end/client_interceptors_end2end_test.cc
+  deps:
+  - grpc++_test_util
+  - grpc_test_util
+  - grpc++
+  - grpc
+  - gpr_test_util
+  - gpr
 - name: client_lb_end2end_test
   gtest: true
   build: test
@@ -5379,6 +5458,22 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
+- name: server_interceptors_end2end_test
+  gtest: true
+  cpu_cost: 0.5
+  build: test
+  language: c++
+  headers:
+  - test/cpp/end2end/interceptors_util.h
+  src:
+  - test/cpp/end2end/server_interceptors_end2end_test.cc
+  deps:
+  - grpc++_test_util
+  - grpc_test_util
+  - grpc++
+  - grpc
+  - gpr_test_util
+  - gpr
 - name: server_request_call_test
   gtest: true
   build: test

config.m4

@@ -234,6 +234,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/transport/timeout_encoding.cc \
     src/core/lib/transport/transport.cc \
     src/core/lib/transport/transport_op_string.cc \
+    src/core/lib/uri/uri_parser.cc \
     src/core/lib/debug/trace.cc \
     src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc \
     src/core/ext/transport/chttp2/transport/bin_decoder.cc \
@@ -280,11 +281,14 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/security/credentials/oauth2/oauth2_credentials.cc \
     src/core/lib/security/credentials/plugin/plugin_credentials.cc \
     src/core/lib/security/credentials/ssl/ssl_credentials.cc \
-    src/core/lib/security/security_connector/alts_security_connector.cc \
+    src/core/lib/security/security_connector/alts/alts_security_connector.cc \
+    src/core/lib/security/security_connector/fake/fake_security_connector.cc \
     src/core/lib/security/security_connector/load_system_roots_fallback.cc \
     src/core/lib/security/security_connector/load_system_roots_linux.cc \
-    src/core/lib/security/security_connector/local_security_connector.cc \
+    src/core/lib/security/security_connector/local/local_security_connector.cc \
     src/core/lib/security/security_connector/security_connector.cc \
+    src/core/lib/security/security_connector/ssl/ssl_security_connector.cc \
+    src/core/lib/security/security_connector/ssl_utils.cc \
     src/core/lib/security/transport/client_auth_filter.cc \
     src/core/lib/security/transport/secure_endpoint.cc \
     src/core/lib/security/transport/security_handshaker.cc \
@@ -339,6 +343,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/connector.cc \
+    src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
@@ -353,8 +358,8 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/retry_throttle.cc \
     src/core/ext/filters/client_channel/subchannel.cc \
     src/core/ext/filters/client_channel/subchannel_index.cc \
-    src/core/ext/filters/client_channel/uri_parser.cc \
     src/core/ext/filters/deadline/deadline_filter.cc \
+    src/core/ext/filters/client_channel/health/health.pb.c \
     src/core/tsi/alts_transport_security.cc \
     src/core/tsi/fake_transport_security.cc \
     src/core/tsi/local_transport_security.cc \
@@ -374,10 +379,14 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc \
+    src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c \
     src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c \
-    src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc \
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
@@ -663,11 +672,13 @@ if test "$PHP_GRPC" != "no"; then
   PHP_ADD_BUILD_DIR($ext_builddir/src/boringssl)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/census)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/health)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/grpclb)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/pick_first)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/round_robin)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/xds)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/resolver/dns/c_ares)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/resolver/dns/native)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/resolver/fake)
@@ -713,11 +724,16 @@ if test "$PHP_GRPC" != "no"; then
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/credentials/plugin)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/credentials/ssl)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/security_connector)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/security_connector/alts)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/security_connector/fake)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/security_connector/local)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/security_connector/ssl)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/transport)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/security/util)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/slice)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/surface)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/transport)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/lib/uri)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/plugin_registry)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/tsi)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/tsi/alts/crypt)

config.w32

@@ -209,6 +209,7 @@ if (PHP_GRPC != "no") {
     "src\\core\\lib\\transport\\timeout_encoding.cc " +
     "src\\core\\lib\\transport\\transport.cc " +
     "src\\core\\lib\\transport\\transport_op_string.cc " +
+    "src\\core\\lib\\uri\\uri_parser.cc " +
     "src\\core\\lib\\debug\\trace.cc " +
     "src\\core\\ext\\transport\\chttp2\\server\\secure\\server_secure_chttp2.cc " +
     "src\\core\\ext\\transport\\chttp2\\transport\\bin_decoder.cc " +
@@ -255,11 +256,14 @@ if (PHP_GRPC != "no") {
     "src\\core\\lib\\security\\credentials\\oauth2\\oauth2_credentials.cc " +
     "src\\core\\lib\\security\\credentials\\plugin\\plugin_credentials.cc " +
     "src\\core\\lib\\security\\credentials\\ssl\\ssl_credentials.cc " +
-    "src\\core\\lib\\security\\security_connector\\alts_security_connector.cc " +
+    "src\\core\\lib\\security\\security_connector\\alts\\alts_security_connector.cc " +
+    "src\\core\\lib\\security\\security_connector\\fake\\fake_security_connector.cc " +
     "src\\core\\lib\\security\\security_connector\\load_system_roots_fallback.cc " +
     "src\\core\\lib\\security\\security_connector\\load_system_roots_linux.cc " +
-    "src\\core\\lib\\security\\security_connector\\local_security_connector.cc " +
+    "src\\core\\lib\\security\\security_connector\\local\\local_security_connector.cc " +
     "src\\core\\lib\\security\\security_connector\\security_connector.cc " +
+    "src\\core\\lib\\security\\security_connector\\ssl\\ssl_security_connector.cc " +
+    "src\\core\\lib\\security\\security_connector\\ssl_utils.cc " +
     "src\\core\\lib\\security\\transport\\client_auth_filter.cc " +
     "src\\core\\lib\\security\\transport\\secure_endpoint.cc " +
     "src\\core\\lib\\security\\transport\\security_handshaker.cc " +
@@ -314,6 +318,7 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\filters\\client_channel\\client_channel_factory.cc " +
     "src\\core\\ext\\filters\\client_channel\\client_channel_plugin.cc " +
     "src\\core\\ext\\filters\\client_channel\\connector.cc " +
+    "src\\core\\ext\\filters\\client_channel\\health\\health_check_client.cc " +
     "src\\core\\ext\\filters\\client_channel\\http_connect_handshaker.cc " +
     "src\\core\\ext\\filters\\client_channel\\http_proxy.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy.cc " +
@@ -328,8 +333,8 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\filters\\client_channel\\retry_throttle.cc " +
     "src\\core\\ext\\filters\\client_channel\\subchannel.cc " +
     "src\\core\\ext\\filters\\client_channel\\subchannel_index.cc " +
-    "src\\core\\ext\\filters\\client_channel\\uri_parser.cc " +
     "src\\core\\ext\\filters\\deadline\\deadline_filter.cc " +
+    "src\\core\\ext\\filters\\client_channel\\health\\health.pb.c " +
     "src\\core\\tsi\\alts_transport_security.cc " +
     "src\\core\\tsi\\fake_transport_security.cc " +
     "src\\core\\tsi\\local_transport_security.cc " +
@@ -349,10 +354,14 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\grpclb_channel_secure.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\grpclb_client_stats.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\load_balancer_api.cc " +
+    "src\\core\\ext\\filters\\client_channel\\resolver\\fake\\fake_resolver.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\proto\\grpc\\lb\\v1\\google\\protobuf\\duration.pb.c " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\proto\\grpc\\lb\\v1\\google\\protobuf\\timestamp.pb.c " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\proto\\grpc\\lb\\v1\\load_balancer.pb.c " +
-    "src\\core\\ext\\filters\\client_channel\\resolver\\fake\\fake_resolver.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds_channel_secure.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds_client_stats.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds_load_balancer_api.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\pick_first\\pick_first.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\round_robin\\round_robin.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\dns_resolver_ares.cc " +
@@ -668,6 +677,7 @@ if (PHP_GRPC != "no") {
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\census");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\health");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\proto");
@@ -678,6 +688,7 @@ if (PHP_GRPC != "no") {
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\proto\\grpc\\lb\\v1\\google\\protobuf");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\pick_first");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\round_robin");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\xds");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\resolver");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\resolver\\dns");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares");
@@ -729,11 +740,16 @@ if (PHP_GRPC != "no") {
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\credentials\\plugin");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\credentials\\ssl");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\security_connector");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\security_connector\\alts");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\security_connector\\fake");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\security_connector\\local");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\security_connector\\ssl");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\transport");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\security\\util");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\slice");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\surface");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\transport");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\lib\\uri");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\plugin_registry");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\tsi");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\tsi\\alts");

doc/PROTOCOL-HTTP2.md

@@ -92,7 +92,7 @@ The repeated sequence of **Length-Prefixed-Message** items is delivered in DATA
 
 * **Length-Prefixed-Message** → Compressed-Flag Message-Length Message
 * <a name="compressed-flag"></a>**Compressed-Flag** → 0 / 1   # encoded as 1 byte unsigned integer
-* **Message-Length** → {_length of Message_}  # encoded as 4 byte unsigned integer
+* **Message-Length** → {_length of Message_}  # encoded as 4 byte unsigned integer (big endian)
 * **Message** → \*{binary octet}
 
 A **Compressed-Flag** value of 1 indicates that the binary octet sequence of **Message** is compressed using the mechanism declared by the **Message-Encoding** header. A value of 0 indicates that no encoding of **Message** bytes has occurred. Compression contexts are NOT maintained over message boundaries, implementations must create a new context for each message in the stream. If the **Message-Encoding** header is omitted then the **Compressed-Flag** must be 0.

doc/connectivity-semantics-and-api.md

@@ -23,9 +23,10 @@ make progress on one of the steps involved in name resolution, TCP connection
 establishment or TLS handshake. This may be used as the initial state for channels upon
 creation.
 
-READY: The channel has successfully established a connection all the way
-through TLS handshake (or equivalent) and all subsequent attempt to communicate
-have succeeded (or are pending without any known failure ).
+READY: The channel has successfully established a connection all the way through
+TLS handshake (or equivalent) and protocol-level (HTTP/2, etc) handshaking, and
+all subsequent attempt to communicate have succeeded (or are pending without any
+known failure).
 
 TRANSIENT_FAILURE: There has been some transient failure (such as a TCP 3-way
 handshake timing out or a socket error). Channels in this state will eventually
@@ -52,8 +53,8 @@ immediately. Pending RPCs may continue running till the application cancels them
 Channels may enter this state either because the application explicitly requested
 a shutdown or if a non-recoverable error has happened during attempts to connect
 communicate . (As of 6/12/2015, there are no known errors (while connecting or
-communicating) that are classified as non-recoverable) 
-Channels that enter this state never leave this state. 
+communicating) that are classified as non-recoverable.)  Channels that enter this
+state never leave this state.
 
 The following table lists the legal transitions from one state to another and
 corresponding reasons. Empty cells denote disallowed transitions.

doc/environment_variables.md

@@ -52,6 +52,7 @@ some configuration as environment variables that can be set.
     traces epoll-fd creation/close calls for epollex polling engine
   - glb - traces the grpclb load balancer
   - handshaker - traces handshaking state
+  - health_check_client - traces health checking client code
   - http - traces state in the http2 transport engine
   - http2_stream_state - traces all http2 stream state mutations.
   - http1 - traces HTTP/1.x operations performed by gRPC

examples/python/helloworld/greeter_client_with_options.py

@@ -0,0 +1,44 @@
+# Copyright 2018 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""The Python implementation of the GRPC helloworld.Greeter client with channel options and call timeout parameters."""
+
+from __future__ import print_function
+
+import grpc
+
+import helloworld_pb2
+import helloworld_pb2_grpc
+
+
+def run():
+    # NOTE(gRPC Python Team): .close() is possible on a channel and should be
+    # used in circumstances in which the with statement does not fit the needs
+    # of the code.
+    #
+    # For more channel options, please see https://grpc.io/grpc/core/group__grpc__arg__keys.html
+    with grpc.insecure_channel(
+            target='localhost:50051',
+            options=[('grpc.lb_policy_name', 'pick_first'),
+                     ('grpc.enable_retries', 0), ('grpc.keepalive_timeout_ms',
+                                                  10000)]) as channel:
+        stub = helloworld_pb2_grpc.GreeterStub(channel)
+        # Timeout in seconds.
+        # Please refer gRPC Python documents for more detail. https://grpc.io/grpc/python/grpc.html
+        response = stub.SayHello(
+            helloworld_pb2.HelloRequest(name='you'), timeout=10)
+    print("Greeter client received: " + response.message)
+
+
+if __name__ == '__main__':
+    run()

gRPC-C++.podspec

@@ -69,6 +69,9 @@ Pod::Spec.new do |s|
 
   s.default_subspecs = 'Interface', 'Implementation'
 
+  # Certificates, to be able to establish TLS connections:
+  s.resource_bundles = { 'gRPCCertificates' => ['etc/roots.pem'] }
+
   s.header_mappings_dir = 'include/grpcpp'
 
   s.subspec 'Interface' do |ss|
@@ -115,6 +118,7 @@ Pod::Spec.new do |s|
                       'include/grpcpp/support/config.h',
                       'include/grpcpp/support/proto_buffer_reader.h',
                       'include/grpcpp/support/proto_buffer_writer.h',
+                      'include/grpcpp/support/server_callback.h',
                       'include/grpcpp/support/slice.h',
                       'include/grpcpp/support/status.h',
                       'include/grpcpp/support/status_code_enum.h',
@@ -128,6 +132,8 @@ Pod::Spec.new do |s|
                       'include/grpcpp/impl/codegen/byte_buffer.h',
                       'include/grpcpp/impl/codegen/call.h',
                       'include/grpcpp/impl/codegen/call_hook.h',
+                      'include/grpcpp/impl/codegen/call_op_set.h',
+                      'include/grpcpp/impl/codegen/call_op_set_interface.h',
                       'include/grpcpp/impl/codegen/callback_common.h',
                       'include/grpcpp/impl/codegen/channel_interface.h',
                       'include/grpcpp/impl/codegen/client_callback.h',
@@ -140,14 +146,18 @@ Pod::Spec.new do |s|
                       'include/grpcpp/impl/codegen/core_codegen_interface.h',
                       'include/grpcpp/impl/codegen/create_auth_context.h',
                       'include/grpcpp/impl/codegen/grpc_library.h',
+                      'include/grpcpp/impl/codegen/intercepted_channel.h',
                       'include/grpcpp/impl/codegen/interceptor.h',
+                      'include/grpcpp/impl/codegen/interceptor_common.h',
                       'include/grpcpp/impl/codegen/metadata_map.h',
                       'include/grpcpp/impl/codegen/method_handler_impl.h',
                       'include/grpcpp/impl/codegen/rpc_method.h',
                       'include/grpcpp/impl/codegen/rpc_service_method.h',
                       'include/grpcpp/impl/codegen/security/auth_context.h',
                       'include/grpcpp/impl/codegen/serialization_traits.h',
+                      'include/grpcpp/impl/codegen/server_callback.h',
                       'include/grpcpp/impl/codegen/server_context.h',
+                      'include/grpcpp/impl/codegen/server_interceptor.h',
                       'include/grpcpp/impl/codegen/server_interface.h',
                       'include/grpcpp/impl/codegen/service_type.h',
                       'include/grpcpp/impl/codegen/slice.h',
@@ -173,7 +183,6 @@ Pod::Spec.new do |s|
                       'src/cpp/common/channel_filter.h',
                       'src/cpp/server/dynamic_thread_pool.h',
                       'src/cpp/server/health/default_health_check_service.h',
-                      'src/cpp/server/health/health.pb.h',
                       'src/cpp/server/thread_pool_interface.h',
                       'src/cpp/thread_manager/thread_manager.h',
                       'src/cpp/client/insecure_credentials.cc',
@@ -204,7 +213,6 @@ Pod::Spec.new do |s|
                       'src/cpp/server/create_default_thread_pool.cc',
                       'src/cpp/server/dynamic_thread_pool.cc',
                       'src/cpp/server/health/default_health_check_service.cc',
-                      'src/cpp/server/health/health.pb.c',
                       'src/cpp/server/health/health_check_service.cc',
                       'src/cpp/server/health/health_check_service_server_builder_option.cc',
                       'src/cpp/server/server_builder.cc',
@@ -269,6 +277,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/http/message_compress/message_compress_filter.h',
                       'src/core/ext/filters/http/server/http_server_filter.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
                       'src/core/lib/security/context/security_context.h',
                       'src/core/lib/security/credentials/alts/alts_credentials.h',
                       'src/core/lib/security/credentials/composite/composite_credentials.h',
@@ -283,11 +292,14 @@ Pod::Spec.new do |s|
                       'src/core/lib/security/credentials/oauth2/oauth2_credentials.h',
                       'src/core/lib/security/credentials/plugin/plugin_credentials.h',
                       'src/core/lib/security/credentials/ssl/ssl_credentials.h',
-                      'src/core/lib/security/security_connector/alts_security_connector.h',
+                      'src/core/lib/security/security_connector/alts/alts_security_connector.h',
+                      'src/core/lib/security/security_connector/fake/fake_security_connector.h',
                       'src/core/lib/security/security_connector/load_system_roots.h',
                       'src/core/lib/security/security_connector/load_system_roots_linux.h',
-                      'src/core/lib/security/security_connector/local_security_connector.h',
+                      'src/core/lib/security/security_connector/local/local_security_connector.h',
                       'src/core/lib/security/security_connector/security_connector.h',
+                      'src/core/lib/security/security_connector/ssl/ssl_security_connector.h',
+                      'src/core/lib/security/security_connector/ssl_utils.h',
                       'src/core/lib/security/transport/auth_filters.h',
                       'src/core/lib/security/transport/secure_endpoint.h',
                       'src/core/lib/security/transport/security_handshaker.h',
@@ -328,6 +340,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/client_channel_channelz.h',
                       'src/core/ext/filters/client_channel/client_channel_factory.h',
                       'src/core/ext/filters/client_channel/connector.h',
+                      'src/core/ext/filters/client_channel/health/health_check_client.h',
                       'src/core/ext/filters/client_channel/http_connect_handshaker.h',
                       'src/core/ext/filters/client_channel/http_proxy.h',
                       'src/core/ext/filters/client_channel/lb_policy.h',
@@ -343,8 +356,8 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/retry_throttle.h',
                       'src/core/ext/filters/client_channel/subchannel.h',
                       'src/core/ext/filters/client_channel/subchannel_index.h',
-                      'src/core/ext/filters/client_channel/uri_parser.h',
                       'src/core/ext/filters/deadline/deadline_filter.h',
+                      'src/core/ext/filters/client_channel/health/health.pb.h',
                       'src/core/tsi/alts_transport_security.h',
                       'src/core/tsi/fake_transport_security.h',
                       'src/core/tsi/local_transport_security.h',
@@ -490,15 +503,19 @@ Pod::Spec.new do |s|
                       'src/core/lib/transport/timeout_encoding.h',
                       'src/core/lib/transport/transport.h',
                       'src/core/lib/transport/transport_impl.h',
+                      'src/core/lib/uri/uri_parser.h',
                       'src/core/lib/debug/trace.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
+                      'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
-                      'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h',
                       'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h',
@@ -516,7 +533,6 @@ Pod::Spec.new do |s|
                               'src/cpp/common/channel_filter.h',
                               'src/cpp/server/dynamic_thread_pool.h',
                               'src/cpp/server/health/default_health_check_service.h',
-                              'src/cpp/server/health/health.pb.h',
                               'src/cpp/server/thread_pool_interface.h',
                               'src/cpp/thread_manager/thread_manager.h',
                               'src/core/lib/gpr/alloc.h',
@@ -679,8 +695,10 @@ Pod::Spec.new do |s|
                               'src/core/lib/transport/timeout_encoding.h',
                               'src/core/lib/transport/transport.h',
                               'src/core/lib/transport/transport_impl.h',
+                              'src/core/lib/uri/uri_parser.h',
                               'src/core/lib/debug/trace.h',
-                              'src/core/ext/transport/inproc/inproc_transport.h'
+                              'src/core/ext/transport/inproc/inproc_transport.h',
+                              'src/core/ext/filters/client_channel/health/health.pb.h'
   end
 
   s.subspec 'Protobuf' do |ss|

gRPC-Core.podspec

@@ -276,6 +276,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/http/message_compress/message_compress_filter.h',
                       'src/core/ext/filters/http/server/http_server_filter.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
                       'src/core/lib/security/context/security_context.h',
                       'src/core/lib/security/credentials/alts/alts_credentials.h',
                       'src/core/lib/security/credentials/composite/composite_credentials.h',
@@ -290,11 +291,14 @@ Pod::Spec.new do |s|
                       'src/core/lib/security/credentials/oauth2/oauth2_credentials.h',
                       'src/core/lib/security/credentials/plugin/plugin_credentials.h',
                       'src/core/lib/security/credentials/ssl/ssl_credentials.h',
-                      'src/core/lib/security/security_connector/alts_security_connector.h',
+                      'src/core/lib/security/security_connector/alts/alts_security_connector.h',
+                      'src/core/lib/security/security_connector/fake/fake_security_connector.h',
                       'src/core/lib/security/security_connector/load_system_roots.h',
                       'src/core/lib/security/security_connector/load_system_roots_linux.h',
-                      'src/core/lib/security/security_connector/local_security_connector.h',
+                      'src/core/lib/security/security_connector/local/local_security_connector.h',
                       'src/core/lib/security/security_connector/security_connector.h',
+                      'src/core/lib/security/security_connector/ssl/ssl_security_connector.h',
+                      'src/core/lib/security/security_connector/ssl_utils.h',
                       'src/core/lib/security/transport/auth_filters.h',
                       'src/core/lib/security/transport/secure_endpoint.h',
                       'src/core/lib/security/transport/security_handshaker.h',
@@ -335,6 +339,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/client_channel_channelz.h',
                       'src/core/ext/filters/client_channel/client_channel_factory.h',
                       'src/core/ext/filters/client_channel/connector.h',
+                      'src/core/ext/filters/client_channel/health/health_check_client.h',
                       'src/core/ext/filters/client_channel/http_connect_handshaker.h',
                       'src/core/ext/filters/client_channel/http_proxy.h',
                       'src/core/ext/filters/client_channel/lb_policy.h',
@@ -350,8 +355,8 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/retry_throttle.h',
                       'src/core/ext/filters/client_channel/subchannel.h',
                       'src/core/ext/filters/client_channel/subchannel_index.h',
-                      'src/core/ext/filters/client_channel/uri_parser.h',
                       'src/core/ext/filters/deadline/deadline_filter.h',
+                      'src/core/ext/filters/client_channel/health/health.pb.h',
                       'src/core/tsi/alts_transport_security.h',
                       'src/core/tsi/fake_transport_security.h',
                       'src/core/tsi/local_transport_security.h',
@@ -497,15 +502,19 @@ Pod::Spec.new do |s|
                       'src/core/lib/transport/timeout_encoding.h',
                       'src/core/lib/transport/transport.h',
                       'src/core/lib/transport/transport_impl.h',
+                      'src/core/lib/uri/uri_parser.h',
                       'src/core/lib/debug/trace.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
+                      'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
-                      'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h',
                       'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h',
@@ -665,6 +674,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/transport/timeout_encoding.cc',
                       'src/core/lib/transport/transport.cc',
                       'src/core/lib/transport/transport_op_string.cc',
+                      'src/core/lib/uri/uri_parser.cc',
                       'src/core/lib/debug/trace.cc',
                       'src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc',
                       'src/core/ext/transport/chttp2/transport/bin_decoder.cc',
@@ -711,11 +721,14 @@ Pod::Spec.new do |s|
                       'src/core/lib/security/credentials/oauth2/oauth2_credentials.cc',
                       'src/core/lib/security/credentials/plugin/plugin_credentials.cc',
                       'src/core/lib/security/credentials/ssl/ssl_credentials.cc',
-                      'src/core/lib/security/security_connector/alts_security_connector.cc',
+                      'src/core/lib/security/security_connector/alts/alts_security_connector.cc',
+                      'src/core/lib/security/security_connector/fake/fake_security_connector.cc',
                       'src/core/lib/security/security_connector/load_system_roots_fallback.cc',
                       'src/core/lib/security/security_connector/load_system_roots_linux.cc',
-                      'src/core/lib/security/security_connector/local_security_connector.cc',
+                      'src/core/lib/security/security_connector/local/local_security_connector.cc',
                       'src/core/lib/security/security_connector/security_connector.cc',
+                      'src/core/lib/security/security_connector/ssl/ssl_security_connector.cc',
+                      'src/core/lib/security/security_connector/ssl_utils.cc',
                       'src/core/lib/security/transport/client_auth_filter.cc',
                       'src/core/lib/security/transport/secure_endpoint.cc',
                       'src/core/lib/security/transport/security_handshaker.cc',
@@ -767,6 +780,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/client_channel_factory.cc',
                       'src/core/ext/filters/client_channel/client_channel_plugin.cc',
                       'src/core/ext/filters/client_channel/connector.cc',
+                      'src/core/ext/filters/client_channel/health/health_check_client.cc',
                       'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
                       'src/core/ext/filters/client_channel/http_proxy.cc',
                       'src/core/ext/filters/client_channel/lb_policy.cc',
@@ -781,8 +795,8 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/retry_throttle.cc',
                       'src/core/ext/filters/client_channel/subchannel.cc',
                       'src/core/ext/filters/client_channel/subchannel_index.cc',
-                      'src/core/ext/filters/client_channel/uri_parser.cc',
                       'src/core/ext/filters/deadline/deadline_filter.cc',
+                      'src/core/ext/filters/client_channel/health/health.pb.c',
                       'src/core/tsi/alts_transport_security.cc',
                       'src/core/tsi/fake_transport_security.cc',
                       'src/core/tsi/local_transport_security.cc',
@@ -802,10 +816,14 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc',
+                      'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c',
-                      'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc',
                       'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
                       'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
@@ -877,6 +895,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/http/message_compress/message_compress_filter.h',
                               'src/core/ext/filters/http/server/http_server_filter.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',
+                              'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
                               'src/core/lib/security/context/security_context.h',
                               'src/core/lib/security/credentials/alts/alts_credentials.h',
                               'src/core/lib/security/credentials/composite/composite_credentials.h',
@@ -891,11 +910,14 @@ Pod::Spec.new do |s|
                               'src/core/lib/security/credentials/oauth2/oauth2_credentials.h',
                               'src/core/lib/security/credentials/plugin/plugin_credentials.h',
                               'src/core/lib/security/credentials/ssl/ssl_credentials.h',
-                              'src/core/lib/security/security_connector/alts_security_connector.h',
+                              'src/core/lib/security/security_connector/alts/alts_security_connector.h',
+                              'src/core/lib/security/security_connector/fake/fake_security_connector.h',
                               'src/core/lib/security/security_connector/load_system_roots.h',
                               'src/core/lib/security/security_connector/load_system_roots_linux.h',
-                              'src/core/lib/security/security_connector/local_security_connector.h',
+                              'src/core/lib/security/security_connector/local/local_security_connector.h',
                               'src/core/lib/security/security_connector/security_connector.h',
+                              'src/core/lib/security/security_connector/ssl/ssl_security_connector.h',
+                              'src/core/lib/security/security_connector/ssl_utils.h',
                               'src/core/lib/security/transport/auth_filters.h',
                               'src/core/lib/security/transport/secure_endpoint.h',
                               'src/core/lib/security/transport/security_handshaker.h',
@@ -936,6 +958,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/client_channel_channelz.h',
                               'src/core/ext/filters/client_channel/client_channel_factory.h',
                               'src/core/ext/filters/client_channel/connector.h',
+                              'src/core/ext/filters/client_channel/health/health_check_client.h',
                               'src/core/ext/filters/client_channel/http_connect_handshaker.h',
                               'src/core/ext/filters/client_channel/http_proxy.h',
                               'src/core/ext/filters/client_channel/lb_policy.h',
@@ -951,8 +974,8 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/retry_throttle.h',
                               'src/core/ext/filters/client_channel/subchannel.h',
                               'src/core/ext/filters/client_channel/subchannel_index.h',
-                              'src/core/ext/filters/client_channel/uri_parser.h',
                               'src/core/ext/filters/deadline/deadline_filter.h',
+                              'src/core/ext/filters/client_channel/health/health.pb.h',
                               'src/core/tsi/alts_transport_security.h',
                               'src/core/tsi/fake_transport_security.h',
                               'src/core/tsi/local_transport_security.h',
@@ -1098,15 +1121,19 @@ Pod::Spec.new do |s|
                               'src/core/lib/transport/timeout_encoding.h',
                               'src/core/lib/transport/transport.h',
                               'src/core/lib/transport/transport_impl.h',
+                              'src/core/lib/uri/uri_parser.h',
                               'src/core/lib/debug/trace.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
+                              'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
-                              'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h',
+                              'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h',
+                              'src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h',
+                              'src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h',
                               'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
                               'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h',
                               'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h',
@@ -1195,6 +1222,9 @@ Pod::Spec.new do |s|
                       'test/core/util/tracer_util.cc',
                       'test/core/util/trickle_endpoint.cc',
                       'test/core/util/cmdline.cc',
+                      'third_party/nanopb/pb_common.c',
+                      'third_party/nanopb/pb_decode.c',
+                      'third_party/nanopb/pb_encode.c',
                       'test/core/end2end/data/ssl_test_data.h',
                       'test/core/security/oauth2_utils.h',
                       'test/core/end2end/cq_verifier.h',
@@ -1216,6 +1246,10 @@ Pod::Spec.new do |s|
                       'test/core/util/tracer_util.h',
                       'test/core/util/trickle_endpoint.h',
                       'test/core/util/cmdline.h',
+                      'third_party/nanopb/pb.h',
+                      'third_party/nanopb/pb_common.h',
+                      'third_party/nanopb/pb_decode.h',
+                      'third_party/nanopb/pb_encode.h',
                       'test/core/end2end/end2end_tests.cc',
                       'test/core/end2end/end2end_test_utils.cc',
                       'test/core/end2end/tests/authority_not_supported.cc',

grpc.def

@@ -75,6 +75,7 @@ EXPORTS
     grpc_resource_quota_arg_vtable
     grpc_channelz_get_top_channels
     grpc_channelz_get_servers
+    grpc_channelz_get_server
     grpc_channelz_get_server_sockets
     grpc_channelz_get_channel
     grpc_channelz_get_subchannel

grpc.gemspec

@@ -208,6 +208,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/http/message_compress/message_compress_filter.h )
   s.files += %w( src/core/ext/filters/http/server/http_server_filter.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds.h )
   s.files += %w( src/core/lib/security/context/security_context.h )
   s.files += %w( src/core/lib/security/credentials/alts/alts_credentials.h )
   s.files += %w( src/core/lib/security/credentials/composite/composite_credentials.h )
@@ -222,11 +223,14 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/security/credentials/oauth2/oauth2_credentials.h )
   s.files += %w( src/core/lib/security/credentials/plugin/plugin_credentials.h )
   s.files += %w( src/core/lib/security/credentials/ssl/ssl_credentials.h )
-  s.files += %w( src/core/lib/security/security_connector/alts_security_connector.h )
+  s.files += %w( src/core/lib/security/security_connector/alts/alts_security_connector.h )
+  s.files += %w( src/core/lib/security/security_connector/fake/fake_security_connector.h )
   s.files += %w( src/core/lib/security/security_connector/load_system_roots.h )
   s.files += %w( src/core/lib/security/security_connector/load_system_roots_linux.h )
-  s.files += %w( src/core/lib/security/security_connector/local_security_connector.h )
+  s.files += %w( src/core/lib/security/security_connector/local/local_security_connector.h )
   s.files += %w( src/core/lib/security/security_connector/security_connector.h )
+  s.files += %w( src/core/lib/security/security_connector/ssl/ssl_security_connector.h )
+  s.files += %w( src/core/lib/security/security_connector/ssl_utils.h )
   s.files += %w( src/core/lib/security/transport/auth_filters.h )
   s.files += %w( src/core/lib/security/transport/secure_endpoint.h )
   s.files += %w( src/core/lib/security/transport/security_handshaker.h )
@@ -271,6 +275,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/client_channel_channelz.h )
   s.files += %w( src/core/ext/filters/client_channel/client_channel_factory.h )
   s.files += %w( src/core/ext/filters/client_channel/connector.h )
+  s.files += %w( src/core/ext/filters/client_channel/health/health_check_client.h )
   s.files += %w( src/core/ext/filters/client_channel/http_connect_handshaker.h )
   s.files += %w( src/core/ext/filters/client_channel/http_proxy.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy.h )
@@ -286,8 +291,8 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/retry_throttle.h )
   s.files += %w( src/core/ext/filters/client_channel/subchannel.h )
   s.files += %w( src/core/ext/filters/client_channel/subchannel_index.h )
-  s.files += %w( src/core/ext/filters/client_channel/uri_parser.h )
   s.files += %w( src/core/ext/filters/deadline/deadline_filter.h )
+  s.files += %w( src/core/ext/filters/client_channel/health/health.pb.h )
   s.files += %w( src/core/tsi/alts_transport_security.h )
   s.files += %w( src/core/tsi/fake_transport_security.h )
   s.files += %w( src/core/tsi/local_transport_security.h )
@@ -433,15 +438,19 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/transport/timeout_encoding.h )
   s.files += %w( src/core/lib/transport/transport.h )
   s.files += %w( src/core/lib/transport/transport_impl.h )
+  s.files += %w( src/core/lib/uri/uri_parser.h )
   s.files += %w( src/core/lib/debug/trace.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h )
+  s.files += %w( src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h )
-  s.files += %w( src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/subchannel_list.h )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h )
@@ -601,6 +610,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/transport/timeout_encoding.cc )
   s.files += %w( src/core/lib/transport/transport.cc )
   s.files += %w( src/core/lib/transport/transport_op_string.cc )
+  s.files += %w( src/core/lib/uri/uri_parser.cc )
   s.files += %w( src/core/lib/debug/trace.cc )
   s.files += %w( src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc )
   s.files += %w( src/core/ext/transport/chttp2/transport/bin_decoder.cc )
@@ -647,11 +657,14 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/security/credentials/oauth2/oauth2_credentials.cc )
   s.files += %w( src/core/lib/security/credentials/plugin/plugin_credentials.cc )
   s.files += %w( src/core/lib/security/credentials/ssl/ssl_credentials.cc )
-  s.files += %w( src/core/lib/security/security_connector/alts_security_connector.cc )
+  s.files += %w( src/core/lib/security/security_connector/alts/alts_security_connector.cc )
+  s.files += %w( src/core/lib/security/security_connector/fake/fake_security_connector.cc )
   s.files += %w( src/core/lib/security/security_connector/load_system_roots_fallback.cc )
   s.files += %w( src/core/lib/security/security_connector/load_system_roots_linux.cc )
-  s.files += %w( src/core/lib/security/security_connector/local_security_connector.cc )
+  s.files += %w( src/core/lib/security/security_connector/local/local_security_connector.cc )
   s.files += %w( src/core/lib/security/security_connector/security_connector.cc )
+  s.files += %w( src/core/lib/security/security_connector/ssl/ssl_security_connector.cc )
+  s.files += %w( src/core/lib/security/security_connector/ssl_utils.cc )
   s.files += %w( src/core/lib/security/transport/client_auth_filter.cc )
   s.files += %w( src/core/lib/security/transport/secure_endpoint.cc )
   s.files += %w( src/core/lib/security/transport/security_handshaker.cc )
@@ -706,6 +719,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/client_channel_factory.cc )
   s.files += %w( src/core/ext/filters/client_channel/client_channel_plugin.cc )
   s.files += %w( src/core/ext/filters/client_channel/connector.cc )
+  s.files += %w( src/core/ext/filters/client_channel/health/health_check_client.cc )
   s.files += %w( src/core/ext/filters/client_channel/http_connect_handshaker.cc )
   s.files += %w( src/core/ext/filters/client_channel/http_proxy.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy.cc )
@@ -720,8 +734,8 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/retry_throttle.cc )
   s.files += %w( src/core/ext/filters/client_channel/subchannel.cc )
   s.files += %w( src/core/ext/filters/client_channel/subchannel_index.cc )
-  s.files += %w( src/core/ext/filters/client_channel/uri_parser.cc )
   s.files += %w( src/core/ext/filters/deadline/deadline_filter.cc )
+  s.files += %w( src/core/ext/filters/client_channel/health/health.pb.c )
   s.files += %w( src/core/tsi/alts_transport_security.cc )
   s.files += %w( src/core/tsi/fake_transport_security.cc )
   s.files += %w( src/core/tsi/local_transport_security.cc )
@@ -741,10 +755,14 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc )
+  s.files += %w( src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c )
-  s.files += %w( src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc )

grpc.gyp

@@ -426,6 +426,7 @@
         'src/core/lib/transport/timeout_encoding.cc',
         'src/core/lib/transport/transport.cc',
         'src/core/lib/transport/transport_op_string.cc',
+        'src/core/lib/uri/uri_parser.cc',
         'src/core/lib/debug/trace.cc',
         'src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc',
         'src/core/ext/transport/chttp2/transport/bin_decoder.cc',
@@ -472,11 +473,14 @@
         'src/core/lib/security/credentials/oauth2/oauth2_credentials.cc',
         'src/core/lib/security/credentials/plugin/plugin_credentials.cc',
         'src/core/lib/security/credentials/ssl/ssl_credentials.cc',
-        'src/core/lib/security/security_connector/alts_security_connector.cc',
+        'src/core/lib/security/security_connector/alts/alts_security_connector.cc',
+        'src/core/lib/security/security_connector/fake/fake_security_connector.cc',
         'src/core/lib/security/security_connector/load_system_roots_fallback.cc',
         'src/core/lib/security/security_connector/load_system_roots_linux.cc',
-        'src/core/lib/security/security_connector/local_security_connector.cc',
+        'src/core/lib/security/security_connector/local/local_security_connector.cc',
         'src/core/lib/security/security_connector/security_connector.cc',
+        'src/core/lib/security/security_connector/ssl/ssl_security_connector.cc',
+        'src/core/lib/security/security_connector/ssl_utils.cc',
         'src/core/lib/security/transport/client_auth_filter.cc',
         'src/core/lib/security/transport/secure_endpoint.cc',
         'src/core/lib/security/transport/security_handshaker.cc',
@@ -531,6 +535,7 @@
         'src/core/ext/filters/client_channel/client_channel_factory.cc',
         'src/core/ext/filters/client_channel/client_channel_plugin.cc',
         'src/core/ext/filters/client_channel/connector.cc',
+        'src/core/ext/filters/client_channel/health/health_check_client.cc',
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
         'src/core/ext/filters/client_channel/http_proxy.cc',
         'src/core/ext/filters/client_channel/lb_policy.cc',
@@ -545,8 +550,8 @@
         'src/core/ext/filters/client_channel/retry_throttle.cc',
         'src/core/ext/filters/client_channel/subchannel.cc',
         'src/core/ext/filters/client_channel/subchannel_index.cc',
-        'src/core/ext/filters/client_channel/uri_parser.cc',
         'src/core/ext/filters/deadline/deadline_filter.cc',
+        'src/core/ext/filters/client_channel/health/health.pb.c',
         'src/core/tsi/alts_transport_security.cc',
         'src/core/tsi/fake_transport_security.cc',
         'src/core/tsi/local_transport_security.cc',
@@ -566,10 +571,14 @@
         'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc',
+        'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c',
-        'src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc',
         'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
         'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
@@ -777,6 +786,7 @@
         'src/core/lib/transport/timeout_encoding.cc',
         'src/core/lib/transport/transport.cc',
         'src/core/lib/transport/transport_op_string.cc',
+        'src/core/lib/uri/uri_parser.cc',
         'src/core/lib/debug/trace.cc',
         'src/core/ext/filters/client_channel/backup_poller.cc',
         'src/core/ext/filters/client_channel/channel_connectivity.cc',
@@ -785,6 +795,7 @@
         'src/core/ext/filters/client_channel/client_channel_factory.cc',
         'src/core/ext/filters/client_channel/client_channel_plugin.cc',
         'src/core/ext/filters/client_channel/connector.cc',
+        'src/core/ext/filters/client_channel/health/health_check_client.cc',
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
         'src/core/ext/filters/client_channel/http_proxy.cc',
         'src/core/ext/filters/client_channel/lb_policy.cc',
@@ -799,8 +810,11 @@
         'src/core/ext/filters/client_channel/retry_throttle.cc',
         'src/core/ext/filters/client_channel/subchannel.cc',
         'src/core/ext/filters/client_channel/subchannel_index.cc',
-        'src/core/ext/filters/client_channel/uri_parser.cc',
         'src/core/ext/filters/deadline/deadline_filter.cc',
+        'src/core/ext/filters/client_channel/health/health.pb.c',
+        'third_party/nanopb/pb_common.c',
+        'third_party/nanopb/pb_decode.c',
+        'third_party/nanopb/pb_encode.c',
         'src/core/ext/transport/chttp2/transport/bin_decoder.cc',
         'src/core/ext/transport/chttp2/transport/bin_encoder.cc',
         'src/core/ext/transport/chttp2/transport/chttp2_plugin.cc',
@@ -1011,6 +1025,7 @@
         'src/core/lib/transport/timeout_encoding.cc',
         'src/core/lib/transport/transport.cc',
         'src/core/lib/transport/transport_op_string.cc',
+        'src/core/lib/uri/uri_parser.cc',
         'src/core/lib/debug/trace.cc',
         'src/core/ext/filters/client_channel/backup_poller.cc',
         'src/core/ext/filters/client_channel/channel_connectivity.cc',
@@ -1019,6 +1034,7 @@
         'src/core/ext/filters/client_channel/client_channel_factory.cc',
         'src/core/ext/filters/client_channel/client_channel_plugin.cc',
         'src/core/ext/filters/client_channel/connector.cc',
+        'src/core/ext/filters/client_channel/health/health_check_client.cc',
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
         'src/core/ext/filters/client_channel/http_proxy.cc',
         'src/core/ext/filters/client_channel/lb_policy.cc',
@@ -1033,8 +1049,11 @@
         'src/core/ext/filters/client_channel/retry_throttle.cc',
         'src/core/ext/filters/client_channel/subchannel.cc',
         'src/core/ext/filters/client_channel/subchannel_index.cc',
-        'src/core/ext/filters/client_channel/uri_parser.cc',
         'src/core/ext/filters/deadline/deadline_filter.cc',
+        'src/core/ext/filters/client_channel/health/health.pb.c',
+        'third_party/nanopb/pb_common.c',
+        'third_party/nanopb/pb_decode.c',
+        'third_party/nanopb/pb_encode.c',
         'src/core/ext/transport/chttp2/transport/bin_decoder.cc',
         'src/core/ext/transport/chttp2/transport/bin_encoder.cc',
         'src/core/ext/transport/chttp2/transport/chttp2_plugin.cc',
@@ -1223,6 +1242,7 @@
         'src/core/lib/transport/timeout_encoding.cc',
         'src/core/lib/transport/transport.cc',
         'src/core/lib/transport/transport_op_string.cc',
+        'src/core/lib/uri/uri_parser.cc',
         'src/core/lib/debug/trace.cc',
         'src/core/ext/transport/chttp2/server/insecure/server_chttp2.cc',
         'src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.cc',
@@ -1265,6 +1285,7 @@
         'src/core/ext/filters/client_channel/client_channel_factory.cc',
         'src/core/ext/filters/client_channel/client_channel_plugin.cc',
         'src/core/ext/filters/client_channel/connector.cc',
+        'src/core/ext/filters/client_channel/health/health_check_client.cc',
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
         'src/core/ext/filters/client_channel/http_proxy.cc',
         'src/core/ext/filters/client_channel/lb_policy.cc',
@@ -1279,8 +1300,11 @@
         'src/core/ext/filters/client_channel/retry_throttle.cc',
         'src/core/ext/filters/client_channel/subchannel.cc',
         'src/core/ext/filters/client_channel/subchannel_index.cc',
-        'src/core/ext/filters/client_channel/uri_parser.cc',
         'src/core/ext/filters/deadline/deadline_filter.cc',
+        'src/core/ext/filters/client_channel/health/health.pb.c',
+        'third_party/nanopb/pb_common.c',
+        'third_party/nanopb/pb_decode.c',
+        'third_party/nanopb/pb_encode.c',
         'src/core/ext/transport/inproc/inproc_plugin.cc',
         'src/core/ext/transport/inproc/inproc_transport.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
@@ -1302,9 +1326,10 @@
         'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c',
-        'third_party/nanopb/pb_common.c',
-        'third_party/nanopb/pb_decode.c',
-        'third_party/nanopb/pb_encode.c',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc',
         'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
         'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
         'src/core/ext/filters/census/grpc_context.cc',
@@ -1379,7 +1404,6 @@
         'src/cpp/server/create_default_thread_pool.cc',
         'src/cpp/server/dynamic_thread_pool.cc',
         'src/cpp/server/health/default_health_check_service.cc',
-        'src/cpp/server/health/health.pb.c',
         'src/cpp/server/health/health_check_service.cc',
         'src/cpp/server/health/health_check_service_server_builder_option.cc',
         'src/cpp/server/server_builder.cc',
@@ -1392,6 +1416,10 @@
         'src/cpp/util/status.cc',
         'src/cpp/util/string_ref.cc',
         'src/cpp/util/time_cc.cc',
+        'src/core/ext/filters/client_channel/health/health.pb.c',
+        'third_party/nanopb/pb_common.c',
+        'third_party/nanopb/pb_decode.c',
+        'third_party/nanopb/pb_encode.c',
         'src/cpp/codegen/codegen_init.cc',
       ],
     },
@@ -1526,7 +1554,6 @@
         'src/cpp/server/create_default_thread_pool.cc',
         'src/cpp/server/dynamic_thread_pool.cc',
         'src/cpp/server/health/default_health_check_service.cc',
-        'src/cpp/server/health/health.pb.c',
         'src/cpp/server/health/health_check_service.cc',
         'src/cpp/server/health/health_check_service_server_builder_option.cc',
         'src/cpp/server/server_builder.cc',
@@ -1539,6 +1566,10 @@
         'src/cpp/util/status.cc',
         'src/cpp/util/string_ref.cc',
         'src/cpp/util/time_cc.cc',
+        'src/core/ext/filters/client_channel/health/health.pb.c',
+        'third_party/nanopb/pb_common.c',
+        'third_party/nanopb/pb_decode.c',
+        'third_party/nanopb/pb_encode.c',
         'src/cpp/codegen/codegen_init.cc',
       ],
     },

include/grpc/grpc.h

@@ -248,10 +248,13 @@ GRPCAPI void* grpc_call_arena_alloc(grpc_call* call, size_t size);
     appropriate to call grpc_completion_queue_next or
     grpc_completion_queue_pluck consequent to the failed grpc_call_start_batch
     call.
+    If a call to grpc_call_start_batch with an empty batch returns
+    GRPC_CALL_OK, the tag is put in the completion queue immediately.
     THREAD SAFETY: access to grpc_call_start_batch in multi-threaded environment
     needs to be synchronized. As an optimization, you may synchronize batches
     containing just send operations independently from batches containing just
-    receive operations. */
+    receive operations. Access to grpc_call_start_batch with an empty batch is
+    thread-compatible. */
 GRPCAPI grpc_call_error grpc_call_start_batch(grpc_call* call,
                                               const grpc_op* ops, size_t nops,
                                               void* tag, void* reserved);
@@ -503,6 +506,9 @@ GRPCAPI char* grpc_channelz_get_top_channels(intptr_t start_channel_id);
 /* Gets all servers that exist in the process. */
 GRPCAPI char* grpc_channelz_get_servers(intptr_t start_server_id);
 
+/* Returns a single Server, or else a NOT_FOUND code. */
+GRPCAPI char* grpc_channelz_get_server(intptr_t server_id);
+
 /* Gets all server sockets that exist in the server. */
 GRPCAPI char* grpc_channelz_get_server_sockets(intptr_t server_id,
                                                intptr_t start_socket_id);

include/grpc/impl/codegen/grpc_types.h

@@ -347,6 +347,9 @@ typedef struct {
 /** If set to non zero, surfaces the user agent string to the server. User
     agent is surfaced by default. */
 #define GRPC_ARG_SURFACE_USER_AGENT "grpc.surface_user_agent"
+/** If set, inhibits health checking (which may be enabled via the
+ *  service config.) */
+#define GRPC_ARG_INHIBIT_HEALTH_CHECKING "grpc.inhibit_health_checking"
 /** \} */
 
 /** Result of a grpc call. If the caller satisfies the prerequisites of a

include/grpcpp/channel.h

@@ -20,6 +20,7 @@
 #define GRPCPP_CHANNEL_H
 
 #include <memory>
+#include <mutex>
 
 #include <grpc/grpc.h>
 #include <grpcpp/impl/call.h>
@@ -67,6 +68,7 @@ class Channel final : public ChannelInterface,
       std::unique_ptr<std::vector<
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>>
           interceptor_creators);
+  friend class internal::InterceptedChannel;
   Channel(const grpc::string& host, grpc_channel* c_channel,
           std::unique_ptr<std::vector<
               std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>>
@@ -87,6 +89,10 @@ class Channel final : public ChannelInterface,
 
   CompletionQueue* CallbackCQ() override;
 
+  internal::Call CreateCallInternal(const internal::RpcMethod& method,
+                                    ClientContext* context, CompletionQueue* cq,
+                                    int interceptor_pos) override;
+
   const grpc::string host_;
   grpc_channel* const c_channel_;  // owned
 

include/grpcpp/impl/codegen/async_stream.h

@@ -276,7 +276,7 @@ class ClientAsyncReader final : public ClientAsyncReaderInterface<R> {
   }
 
   void StartCallInternal(void* tag) {
-    init_ops_.SendInitialMetadata(context_->send_initial_metadata_,
+    init_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
                                   context_->initial_metadata_flags());
     init_ops_.set_output_tag(tag);
     call_.PerformOps(&init_ops_);
@@ -441,7 +441,7 @@ class ClientAsyncWriter final : public ClientAsyncWriterInterface<W> {
   }
 
   void StartCallInternal(void* tag) {
-    write_ops_.SendInitialMetadata(context_->send_initial_metadata_,
+    write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
                                    context_->initial_metadata_flags());
     // if corked bit is set in context, we just keep the initial metadata
     // buffered up to coalesce with later message send. No op is performed.
@@ -612,7 +612,7 @@ class ClientAsyncReaderWriter final
   }
 
   void StartCallInternal(void* tag) {
-    write_ops_.SendInitialMetadata(context_->send_initial_metadata_,
+    write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
                                    context_->initial_metadata_flags());
     // if corked bit is set in context, we just keep the initial metadata
     // buffered up to coalesce with later message send. No op is performed.
@@ -710,7 +710,7 @@ class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     meta_ops_.set_output_tag(tag);
-    meta_ops_.SendInitialMetadata(ctx_->initial_metadata_,
+    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                   ctx_->initial_metadata_flags());
     if (ctx_->compression_level_set()) {
       meta_ops_.set_compression_level(ctx_->compression_level());
@@ -739,7 +739,7 @@ class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
   void Finish(const W& msg, const Status& status, void* tag) override {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
-      finish_ops_.SendInitialMetadata(ctx_->initial_metadata_,
+      finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                       ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         finish_ops_.set_compression_level(ctx_->compression_level());
@@ -748,10 +748,10 @@ class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
     }
     // The response is dropped if the status is not OK.
     if (status.ok()) {
-      finish_ops_.ServerSendStatus(ctx_->trailing_metadata_,
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
                                    finish_ops_.SendMessage(msg));
     } else {
-      finish_ops_.ServerSendStatus(ctx_->trailing_metadata_, status);
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     }
     call_.PerformOps(&finish_ops_);
   }
@@ -769,14 +769,14 @@ class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
     GPR_CODEGEN_ASSERT(!status.ok());
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
-      finish_ops_.SendInitialMetadata(ctx_->initial_metadata_,
+      finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                       ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         finish_ops_.set_compression_level(ctx_->compression_level());
       }
       ctx_->sent_initial_metadata_ = true;
     }
-    finish_ops_.ServerSendStatus(ctx_->trailing_metadata_, status);
+    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     call_.PerformOps(&finish_ops_);
   }
 
@@ -859,7 +859,7 @@ class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     meta_ops_.set_output_tag(tag);
-    meta_ops_.SendInitialMetadata(ctx_->initial_metadata_,
+    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                   ctx_->initial_metadata_flags());
     if (ctx_->compression_level_set()) {
       meta_ops_.set_compression_level(ctx_->compression_level());
@@ -904,7 +904,7 @@ class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
     EnsureInitialMetadataSent(&write_ops_);
     options.set_buffer_hint();
     GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    write_ops_.ServerSendStatus(ctx_->trailing_metadata_, status);
+    write_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     call_.PerformOps(&write_ops_);
   }
 
@@ -922,7 +922,7 @@ class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
   void Finish(const Status& status, void* tag) override {
     finish_ops_.set_output_tag(tag);
     EnsureInitialMetadataSent(&finish_ops_);
-    finish_ops_.ServerSendStatus(ctx_->trailing_metadata_, status);
+    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     call_.PerformOps(&finish_ops_);
   }
 
@@ -932,7 +932,7 @@ class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
   template <class T>
   void EnsureInitialMetadataSent(T* ops) {
     if (!ctx_->sent_initial_metadata_) {
-      ops->SendInitialMetadata(ctx_->initial_metadata_,
+      ops->SendInitialMetadata(&ctx_->initial_metadata_,
                                ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         ops->set_compression_level(ctx_->compression_level());
@@ -1025,7 +1025,7 @@ class ServerAsyncReaderWriter final
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     meta_ops_.set_output_tag(tag);
-    meta_ops_.SendInitialMetadata(ctx_->initial_metadata_,
+    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                   ctx_->initial_metadata_flags());
     if (ctx_->compression_level_set()) {
       meta_ops_.set_compression_level(ctx_->compression_level());
@@ -1075,7 +1075,7 @@ class ServerAsyncReaderWriter final
     EnsureInitialMetadataSent(&write_ops_);
     options.set_buffer_hint();
     GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    write_ops_.ServerSendStatus(ctx_->trailing_metadata_, status);
+    write_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     call_.PerformOps(&write_ops_);
   }
 
@@ -1094,7 +1094,7 @@ class ServerAsyncReaderWriter final
     finish_ops_.set_output_tag(tag);
     EnsureInitialMetadataSent(&finish_ops_);
 
-    finish_ops_.ServerSendStatus(ctx_->trailing_metadata_, status);
+    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     call_.PerformOps(&finish_ops_);
   }
 
@@ -1106,7 +1106,7 @@ class ServerAsyncReaderWriter final
   template <class T>
   void EnsureInitialMetadataSent(T* ops) {
     if (!ctx_->sent_initial_metadata_) {
-      ops->SendInitialMetadata(ctx_->initial_metadata_,
+      ops->SendInitialMetadata(&ctx_->initial_metadata_,
                                ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         ops->set_compression_level(ctx_->compression_level());

include/grpcpp/impl/codegen/async_unary_call.h

@@ -174,7 +174,7 @@ class ClientAsyncResponseReader final
   }
 
   void StartCallInternal() {
-    single_buf.SendInitialMetadata(context_->send_initial_metadata_,
+    single_buf.SendInitialMetadata(&context_->send_initial_metadata_,
                                    context_->initial_metadata_flags());
   }
 
@@ -214,7 +214,7 @@ class ServerAsyncResponseWriter final
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     meta_buf_.set_output_tag(tag);
-    meta_buf_.SendInitialMetadata(ctx_->initial_metadata_,
+    meta_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
                                   ctx_->initial_metadata_flags());
     if (ctx_->compression_level_set()) {
       meta_buf_.set_compression_level(ctx_->compression_level());
@@ -240,8 +240,9 @@ class ServerAsyncResponseWriter final
   /// metadata.
   void Finish(const W& msg, const Status& status, void* tag) {
     finish_buf_.set_output_tag(tag);
+    finish_buf_.set_core_cq_tag(&finish_buf_);
     if (!ctx_->sent_initial_metadata_) {
-      finish_buf_.SendInitialMetadata(ctx_->initial_metadata_,
+      finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
                                       ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         finish_buf_.set_compression_level(ctx_->compression_level());
@@ -250,10 +251,10 @@ class ServerAsyncResponseWriter final
     }
     // The response is dropped if the status is not OK.
     if (status.ok()) {
-      finish_buf_.ServerSendStatus(ctx_->trailing_metadata_,
+      finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_,
                                    finish_buf_.SendMessage(msg));
     } else {
-      finish_buf_.ServerSendStatus(ctx_->trailing_metadata_, status);
+      finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     }
     call_.PerformOps(&finish_buf_);
   }
@@ -274,14 +275,14 @@ class ServerAsyncResponseWriter final
     GPR_CODEGEN_ASSERT(!status.ok());
     finish_buf_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
-      finish_buf_.SendInitialMetadata(ctx_->initial_metadata_,
+      finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
                                       ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         finish_buf_.set_compression_level(ctx_->compression_level());
       }
       ctx_->sent_initial_metadata_ = true;
     }
-    finish_buf_.ServerSendStatus(ctx_->trailing_metadata_, status);
+    finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, status);
     call_.PerformOps(&finish_buf_);
   }
 

include/grpcpp/impl/codegen/byte_buffer.h

@@ -45,11 +45,18 @@ template <class ServiceType, class RequestType, class ResponseType>
 class RpcMethodHandler;
 template <class ServiceType, class RequestType, class ResponseType>
 class ServerStreamingHandler;
+template <class ServiceType, class RequestType, class ResponseType>
+class CallbackUnaryHandler;
 template <StatusCode code>
 class ErrorMethodHandler;
 template <class R>
 class DeserializeFuncType;
 class GrpcByteBufferPeer;
+template <class ServiceType, class RequestType, class ResponseType>
+class RpcMethodHandler;
+template <class ServiceType, class RequestType, class ResponseType>
+class ServerStreamingHandler;
+
 }  // namespace internal
 /// A sequence of bytes.
 class ByteBuffer final {
@@ -141,11 +148,16 @@ class ByteBuffer final {
   template <class R>
   friend class internal::CallOpRecvMessage;
   friend class internal::CallOpGenericRecvMessage;
-  friend class internal::MethodHandler;
+  template <class ServiceType, class RequestType, class ResponseType>
+  friend class RpcMethodHandler;
+  template <class ServiceType, class RequestType, class ResponseType>
+  friend class ServerStreamingHandler;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class internal::RpcMethodHandler;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class internal::ServerStreamingHandler;
+  template <class ServiceType, class RequestType, class ResponseType>
+  friend class internal::CallbackUnaryHandler;
   template <StatusCode code>
   friend class internal::ErrorMethodHandler;
   template <class R>

include/grpcpp/impl/codegen/call.h

@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015 gRPC authors.
+ * Copyright 2018 gRPC authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,658 +15,31 @@
  * limitations under the License.
  *
  */
-
 #ifndef GRPCPP_IMPL_CODEGEN_CALL_H
 #define GRPCPP_IMPL_CODEGEN_CALL_H
 
-#include <assert.h>
-#include <cstring>
-#include <functional>
-#include <map>
-#include <memory>
-
-#include <grpcpp/impl/codegen/byte_buffer.h>
-#include <grpcpp/impl/codegen/call_hook.h>
-#include <grpcpp/impl/codegen/client_context.h>
-#include <grpcpp/impl/codegen/completion_queue_tag.h>
-#include <grpcpp/impl/codegen/config.h>
-#include <grpcpp/impl/codegen/core_codegen_interface.h>
-#include <grpcpp/impl/codegen/serialization_traits.h>
-#include <grpcpp/impl/codegen/slice.h>
-#include <grpcpp/impl/codegen/status.h>
-#include <grpcpp/impl/codegen/string_ref.h>
-
-#include <grpc/impl/codegen/atm.h>
-#include <grpc/impl/codegen/compression_types.h>
 #include <grpc/impl/codegen/grpc_types.h>
+#include <grpcpp/impl/codegen/call_hook.h>
 
 namespace grpc {
-
-class ByteBuffer;
 class CompletionQueue;
-extern CoreCodegenInterface* g_core_codegen_interface;
 
+namespace experimental {
+class ClientRpcInfo;
+class ServerRpcInfo;
+}  // namespace experimental
 namespace internal {
-class Call;
 class CallHook;
-
-// TODO(yangg) if the map is changed before we send, the pointers will be a
-// mess. Make sure it does not happen.
-inline grpc_metadata* FillMetadataArray(
-    const std::multimap<grpc::string, grpc::string>& metadata,
-    size_t* metadata_count, const grpc::string& optional_error_details) {
-  *metadata_count = metadata.size() + (optional_error_details.empty() ? 0 : 1);
-  if (*metadata_count == 0) {
-    return nullptr;
-  }
-  grpc_metadata* metadata_array =
-      (grpc_metadata*)(g_core_codegen_interface->gpr_malloc(
-          (*metadata_count) * sizeof(grpc_metadata)));
-  size_t i = 0;
-  for (auto iter = metadata.cbegin(); iter != metadata.cend(); ++iter, ++i) {
-    metadata_array[i].key = SliceReferencingString(iter->first);
-    metadata_array[i].value = SliceReferencingString(iter->second);
-  }
-  if (!optional_error_details.empty()) {
-    metadata_array[i].key =
-        g_core_codegen_interface->grpc_slice_from_static_buffer(
-            kBinaryErrorDetailsKey, sizeof(kBinaryErrorDetailsKey) - 1);
-    metadata_array[i].value = SliceReferencingString(optional_error_details);
-  }
-  return metadata_array;
-}
-}  // namespace internal
-
-/// Per-message write options.
-class WriteOptions {
- public:
-  WriteOptions() : flags_(0), last_message_(false) {}
-  WriteOptions(const WriteOptions& other)
-      : flags_(other.flags_), last_message_(other.last_message_) {}
-
-  /// Clear all flags.
-  inline void Clear() { flags_ = 0; }
-
-  /// Returns raw flags bitset.
-  inline uint32_t flags() const { return flags_; }
-
-  /// Sets flag for the disabling of compression for the next message write.
-  ///
-  /// \sa GRPC_WRITE_NO_COMPRESS
-  inline WriteOptions& set_no_compression() {
-    SetBit(GRPC_WRITE_NO_COMPRESS);
-    return *this;
-  }
-
-  /// Clears flag for the disabling of compression for the next message write.
-  ///
-  /// \sa GRPC_WRITE_NO_COMPRESS
-  inline WriteOptions& clear_no_compression() {
-    ClearBit(GRPC_WRITE_NO_COMPRESS);
-    return *this;
-  }
-
-  /// Get value for the flag indicating whether compression for the next
-  /// message write is forcefully disabled.
-  ///
-  /// \sa GRPC_WRITE_NO_COMPRESS
-  inline bool get_no_compression() const {
-    return GetBit(GRPC_WRITE_NO_COMPRESS);
-  }
-
-  /// Sets flag indicating that the write may be buffered and need not go out on
-  /// the wire immediately.
-  ///
-  /// \sa GRPC_WRITE_BUFFER_HINT
-  inline WriteOptions& set_buffer_hint() {
-    SetBit(GRPC_WRITE_BUFFER_HINT);
-    return *this;
-  }
-
-  /// Clears flag indicating that the write may be buffered and need not go out
-  /// on the wire immediately.
-  ///
-  /// \sa GRPC_WRITE_BUFFER_HINT
-  inline WriteOptions& clear_buffer_hint() {
-    ClearBit(GRPC_WRITE_BUFFER_HINT);
-    return *this;
-  }
-
-  /// Get value for the flag indicating that the write may be buffered and need
-  /// not go out on the wire immediately.
-  ///
-  /// \sa GRPC_WRITE_BUFFER_HINT
-  inline bool get_buffer_hint() const { return GetBit(GRPC_WRITE_BUFFER_HINT); }
-
-  /// corked bit: aliases set_buffer_hint currently, with the intent that
-  /// set_buffer_hint will be removed in the future
-  inline WriteOptions& set_corked() {
-    SetBit(GRPC_WRITE_BUFFER_HINT);
-    return *this;
-  }
-
-  inline WriteOptions& clear_corked() {
-    ClearBit(GRPC_WRITE_BUFFER_HINT);
-    return *this;
-  }
-
-  inline bool is_corked() const { return GetBit(GRPC_WRITE_BUFFER_HINT); }
-
-  /// last-message bit: indicates this is the last message in a stream
-  /// client-side:  makes Write the equivalent of performing Write, WritesDone
-  /// in a single step
-  /// server-side:  hold the Write until the service handler returns (sync api)
-  /// or until Finish is called (async api)
-  inline WriteOptions& set_last_message() {
-    last_message_ = true;
-    return *this;
-  }
-
-  /// Clears flag indicating that this is the last message in a stream,
-  /// disabling coalescing.
-  inline WriteOptions& clear_last_message() {
-    last_message_ = false;
-    return *this;
-  }
-
-  /// Guarantee that all bytes have been written to the socket before completing
-  /// this write (usually writes are completed when they pass flow control).
-  inline WriteOptions& set_write_through() {
-    SetBit(GRPC_WRITE_THROUGH);
-    return *this;
-  }
-
-  inline bool is_write_through() const { return GetBit(GRPC_WRITE_THROUGH); }
-
-  /// Get value for the flag indicating that this is the last message, and
-  /// should be coalesced with trailing metadata.
-  ///
-  /// \sa GRPC_WRITE_LAST_MESSAGE
-  bool is_last_message() const { return last_message_; }
-
-  WriteOptions& operator=(const WriteOptions& rhs) {
-    flags_ = rhs.flags_;
-    return *this;
-  }
-
- private:
-  void SetBit(const uint32_t mask) { flags_ |= mask; }
-
-  void ClearBit(const uint32_t mask) { flags_ &= ~mask; }
-
-  bool GetBit(const uint32_t mask) const { return (flags_ & mask) != 0; }
-
-  uint32_t flags_;
-  bool last_message_;
-};
-
-namespace internal {
-/// Default argument for CallOpSet. I is unused by the class, but can be
-/// used for generating multiple names for the same thing.
-template <int I>
-class CallNoOp {
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {}
-  void FinishOp(bool* status) {}
-};
-
-class CallOpSendInitialMetadata {
- public:
-  CallOpSendInitialMetadata() : send_(false) {
-    maybe_compression_level_.is_set = false;
-  }
-
-  void SendInitialMetadata(
-      const std::multimap<grpc::string, grpc::string>& metadata,
-      uint32_t flags) {
-    maybe_compression_level_.is_set = false;
-    send_ = true;
-    flags_ = flags;
-    initial_metadata_ =
-        FillMetadataArray(metadata, &initial_metadata_count_, "");
-  }
-
-  void set_compression_level(grpc_compression_level level) {
-    maybe_compression_level_.is_set = true;
-    maybe_compression_level_.level = level;
-  }
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (!send_) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_SEND_INITIAL_METADATA;
-    op->flags = flags_;
-    op->reserved = NULL;
-    op->data.send_initial_metadata.count = initial_metadata_count_;
-    op->data.send_initial_metadata.metadata = initial_metadata_;
-    op->data.send_initial_metadata.maybe_compression_level.is_set =
-        maybe_compression_level_.is_set;
-    if (maybe_compression_level_.is_set) {
-      op->data.send_initial_metadata.maybe_compression_level.level =
-          maybe_compression_level_.level;
-    }
-  }
-  void FinishOp(bool* status) {
-    if (!send_) return;
-    g_core_codegen_interface->gpr_free(initial_metadata_);
-    send_ = false;
-  }
-
-  bool send_;
-  uint32_t flags_;
-  size_t initial_metadata_count_;
-  grpc_metadata* initial_metadata_;
-  struct {
-    bool is_set;
-    grpc_compression_level level;
-  } maybe_compression_level_;
-};
-
-class CallOpSendMessage {
- public:
-  CallOpSendMessage() : send_buf_() {}
-
-  /// Send \a message using \a options for the write. The \a options are cleared
-  /// after use.
-  template <class M>
-  Status SendMessage(const M& message,
-                     WriteOptions options) GRPC_MUST_USE_RESULT;
-
-  template <class M>
-  Status SendMessage(const M& message) GRPC_MUST_USE_RESULT;
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (!send_buf_.Valid()) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_SEND_MESSAGE;
-    op->flags = write_options_.flags();
-    op->reserved = NULL;
-    op->data.send_message.send_message = send_buf_.c_buffer();
-    // Flags are per-message: clear them after use.
-    write_options_.Clear();
-  }
-  void FinishOp(bool* status) { send_buf_.Clear(); }
-
- private:
-  ByteBuffer send_buf_;
-  WriteOptions write_options_;
-};
-
-template <class M>
-Status CallOpSendMessage::SendMessage(const M& message, WriteOptions options) {
-  write_options_ = options;
-  bool own_buf;
-  // TODO(vjpai): Remove the void below when possible
-  // The void in the template parameter below should not be needed
-  // (since it should be implicit) but is needed due to an observed
-  // difference in behavior between clang and gcc for certain internal users
-  Status result = SerializationTraits<M, void>::Serialize(
-      message, send_buf_.bbuf_ptr(), &own_buf);
-  if (!own_buf) {
-    send_buf_.Duplicate();
-  }
-  return result;
-}
-
-template <class M>
-Status CallOpSendMessage::SendMessage(const M& message) {
-  return SendMessage(message, WriteOptions());
-}
-
-template <class R>
-class CallOpRecvMessage {
- public:
-  CallOpRecvMessage()
-      : got_message(false),
-        message_(nullptr),
-        allow_not_getting_message_(false) {}
-
-  void RecvMessage(R* message) { message_ = message; }
-
-  // Do not change status if no message is received.
-  void AllowNoMessage() { allow_not_getting_message_ = true; }
-
-  bool got_message;
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (message_ == nullptr) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_RECV_MESSAGE;
-    op->flags = 0;
-    op->reserved = NULL;
-    op->data.recv_message.recv_message = recv_buf_.c_buffer_ptr();
-  }
-
-  void FinishOp(bool* status) {
-    if (message_ == nullptr) return;
-    if (recv_buf_.Valid()) {
-      if (*status) {
-        got_message = *status =
-            SerializationTraits<R>::Deserialize(recv_buf_.bbuf_ptr(), message_)
-                .ok();
-        recv_buf_.Release();
-      } else {
-        got_message = false;
-        recv_buf_.Clear();
-      }
-    } else {
-      got_message = false;
-      if (!allow_not_getting_message_) {
-        *status = false;
-      }
-    }
-    message_ = nullptr;
-  }
-
- private:
-  R* message_;
-  ByteBuffer recv_buf_;
-  bool allow_not_getting_message_;
-};
-
-class DeserializeFunc {
- public:
-  virtual Status Deserialize(ByteBuffer* buf) = 0;
-  virtual ~DeserializeFunc() {}
-};
-
-template <class R>
-class DeserializeFuncType final : public DeserializeFunc {
- public:
-  DeserializeFuncType(R* message) : message_(message) {}
-  Status Deserialize(ByteBuffer* buf) override {
-    return SerializationTraits<R>::Deserialize(buf->bbuf_ptr(), message_);
-  }
-
-  ~DeserializeFuncType() override {}
-
- private:
-  R* message_;  // Not a managed pointer because management is external to this
-};
-
-class CallOpGenericRecvMessage {
- public:
-  CallOpGenericRecvMessage()
-      : got_message(false), allow_not_getting_message_(false) {}
-
-  template <class R>
-  void RecvMessage(R* message) {
-    // Use an explicit base class pointer to avoid resolution error in the
-    // following unique_ptr::reset for some old implementations.
-    DeserializeFunc* func = new DeserializeFuncType<R>(message);
-    deserialize_.reset(func);
-  }
-
-  // Do not change status if no message is received.
-  void AllowNoMessage() { allow_not_getting_message_ = true; }
-
-  bool got_message;
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (!deserialize_) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_RECV_MESSAGE;
-    op->flags = 0;
-    op->reserved = NULL;
-    op->data.recv_message.recv_message = recv_buf_.c_buffer_ptr();
-  }
-
-  void FinishOp(bool* status) {
-    if (!deserialize_) return;
-    if (recv_buf_.Valid()) {
-      if (*status) {
-        got_message = true;
-        *status = deserialize_->Deserialize(&recv_buf_).ok();
-        recv_buf_.Release();
-      } else {
-        got_message = false;
-        recv_buf_.Clear();
-      }
-    } else {
-      got_message = false;
-      if (!allow_not_getting_message_) {
-        *status = false;
-      }
-    }
-    deserialize_.reset();
-  }
-
- private:
-  std::unique_ptr<DeserializeFunc> deserialize_;
-  ByteBuffer recv_buf_;
-  bool allow_not_getting_message_;
-};
-
-class CallOpClientSendClose {
- public:
-  CallOpClientSendClose() : send_(false) {}
-
-  void ClientSendClose() { send_ = true; }
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (!send_) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
-    op->flags = 0;
-    op->reserved = NULL;
-  }
-  void FinishOp(bool* status) { send_ = false; }
-
- private:
-  bool send_;
-};
-
-class CallOpServerSendStatus {
- public:
-  CallOpServerSendStatus() : send_status_available_(false) {}
-
-  void ServerSendStatus(
-      const std::multimap<grpc::string, grpc::string>& trailing_metadata,
-      const Status& status) {
-    send_error_details_ = status.error_details();
-    trailing_metadata_ = FillMetadataArray(
-        trailing_metadata, &trailing_metadata_count_, send_error_details_);
-    send_status_available_ = true;
-    send_status_code_ = static_cast<grpc_status_code>(status.error_code());
-    send_error_message_ = status.error_message();
-  }
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (!send_status_available_) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
-    op->data.send_status_from_server.trailing_metadata_count =
-        trailing_metadata_count_;
-    op->data.send_status_from_server.trailing_metadata = trailing_metadata_;
-    op->data.send_status_from_server.status = send_status_code_;
-    error_message_slice_ = SliceReferencingString(send_error_message_);
-    op->data.send_status_from_server.status_details =
-        send_error_message_.empty() ? nullptr : &error_message_slice_;
-    op->flags = 0;
-    op->reserved = NULL;
-  }
-
-  void FinishOp(bool* status) {
-    if (!send_status_available_) return;
-    g_core_codegen_interface->gpr_free(trailing_metadata_);
-    send_status_available_ = false;
-  }
-
- private:
-  bool send_status_available_;
-  grpc_status_code send_status_code_;
-  grpc::string send_error_details_;
-  grpc::string send_error_message_;
-  size_t trailing_metadata_count_;
-  grpc_metadata* trailing_metadata_;
-  grpc_slice error_message_slice_;
-};
-
-class CallOpRecvInitialMetadata {
- public:
-  CallOpRecvInitialMetadata() : metadata_map_(nullptr) {}
-
-  void RecvInitialMetadata(ClientContext* context) {
-    context->initial_metadata_received_ = true;
-    metadata_map_ = &context->recv_initial_metadata_;
-  }
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (metadata_map_ == nullptr) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_RECV_INITIAL_METADATA;
-    op->data.recv_initial_metadata.recv_initial_metadata = metadata_map_->arr();
-    op->flags = 0;
-    op->reserved = NULL;
-  }
-
-  void FinishOp(bool* status) {
-    if (metadata_map_ == nullptr) return;
-    metadata_map_ = nullptr;
-  }
-
- private:
-  MetadataMap* metadata_map_;
-};
-
-class CallOpClientRecvStatus {
- public:
-  CallOpClientRecvStatus()
-      : recv_status_(nullptr), debug_error_string_(nullptr) {}
-
-  void ClientRecvStatus(ClientContext* context, Status* status) {
-    client_context_ = context;
-    metadata_map_ = &client_context_->trailing_metadata_;
-    recv_status_ = status;
-    error_message_ = g_core_codegen_interface->grpc_empty_slice();
-  }
-
- protected:
-  void AddOp(grpc_op* ops, size_t* nops) {
-    if (recv_status_ == nullptr) return;
-    grpc_op* op = &ops[(*nops)++];
-    op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
-    op->data.recv_status_on_client.trailing_metadata = metadata_map_->arr();
-    op->data.recv_status_on_client.status = &status_code_;
-    op->data.recv_status_on_client.status_details = &error_message_;
-    op->data.recv_status_on_client.error_string = &debug_error_string_;
-    op->flags = 0;
-    op->reserved = NULL;
-  }
-
-  void FinishOp(bool* status) {
-    if (recv_status_ == nullptr) return;
-    grpc::string binary_error_details = metadata_map_->GetBinaryErrorDetails();
-    *recv_status_ =
-        Status(static_cast<StatusCode>(status_code_),
-               GRPC_SLICE_IS_EMPTY(error_message_)
-                   ? grpc::string()
-                   : grpc::string(GRPC_SLICE_START_PTR(error_message_),
-                                  GRPC_SLICE_END_PTR(error_message_)),
-               binary_error_details);
-    client_context_->set_debug_error_string(
-        debug_error_string_ != nullptr ? debug_error_string_ : "");
-    g_core_codegen_interface->grpc_slice_unref(error_message_);
-    if (debug_error_string_ != nullptr) {
-      g_core_codegen_interface->gpr_free((void*)debug_error_string_);
-    }
-    recv_status_ = nullptr;
-  }
-
- private:
-  ClientContext* client_context_;
-  MetadataMap* metadata_map_;
-  Status* recv_status_;
-  const char* debug_error_string_;
-  grpc_status_code status_code_;
-  grpc_slice error_message_;
-};
-
-/// An abstract collection of call ops, used to generate the
-/// grpc_call_op structure to pass down to the lower layers,
-/// and as it is-a CompletionQueueTag, also massages the final
-/// completion into the correct form for consumption in the C++
-/// API.
-class CallOpSetInterface : public CompletionQueueTag {
- public:
-  /// Fills in grpc_op, starting from ops[*nops] and moving
-  /// upwards.
-  virtual void FillOps(grpc_call* call, grpc_op* ops, size_t* nops) = 0;
-
-  /// Get the tag to be used at the core completion queue. Generally, the
-  /// value of cq_tag will be "this". However, it can be overridden if we
-  /// want core to process the tag differently (e.g., as a core callback)
-  virtual void* cq_tag() = 0;
-};
-
-/// Primary implementation of CallOpSetInterface.
-/// Since we cannot use variadic templates, we declare slots up to
-/// the maximum count of ops we'll need in a set. We leverage the
-/// empty base class optimization to slim this class (especially
-/// when there are many unused slots used). To avoid duplicate base classes,
-/// the template parmeter for CallNoOp is varied by argument position.
-template <class Op1 = CallNoOp<1>, class Op2 = CallNoOp<2>,
-          class Op3 = CallNoOp<3>, class Op4 = CallNoOp<4>,
-          class Op5 = CallNoOp<5>, class Op6 = CallNoOp<6>>
-class CallOpSet : public CallOpSetInterface,
-                  public Op1,
-                  public Op2,
-                  public Op3,
-                  public Op4,
-                  public Op5,
-                  public Op6 {
- public:
-  CallOpSet() : cq_tag_(this), return_tag_(this), call_(nullptr) {}
-  void FillOps(grpc_call* call, grpc_op* ops, size_t* nops) override {
-    this->Op1::AddOp(ops, nops);
-    this->Op2::AddOp(ops, nops);
-    this->Op3::AddOp(ops, nops);
-    this->Op4::AddOp(ops, nops);
-    this->Op5::AddOp(ops, nops);
-    this->Op6::AddOp(ops, nops);
-    g_core_codegen_interface->grpc_call_ref(call);
-    call_ = call;
-  }
-
-  bool FinalizeResult(void** tag, bool* status) override {
-    this->Op1::FinishOp(status);
-    this->Op2::FinishOp(status);
-    this->Op3::FinishOp(status);
-    this->Op4::FinishOp(status);
-    this->Op5::FinishOp(status);
-    this->Op6::FinishOp(status);
-    *tag = return_tag_;
-
-    g_core_codegen_interface->grpc_call_unref(call_);
-    return true;
-  }
-
-  void set_output_tag(void* return_tag) { return_tag_ = return_tag; }
-
-  void* cq_tag() override { return cq_tag_; }
-
-  /// set_cq_tag is used to provide a different core CQ tag than "this".
-  /// This is used for callback-based tags, where the core tag is the core
-  /// callback function. It does not change the use or behavior of any other
-  /// function (such as FinalizeResult)
-  void set_cq_tag(void* cq_tag) { cq_tag_ = cq_tag; }
-
- private:
-  void* cq_tag_;
-  void* return_tag_;
-  grpc_call* call_;
-};
+class CallOpSetInterface;
 
 /// Straightforward wrapping of the C call object
 class Call final {
  public:
+  Call()
+      : call_hook_(nullptr),
+        cq_(nullptr),
+        call_(nullptr),
+        max_receive_message_size_(-1) {}
   /** call is owned by the caller */
   Call(grpc_call* call, CallHook* call_hook, CompletionQueue* cq)
       : call_hook_(call_hook),
@@ -675,11 +48,20 @@ class Call final {
         max_receive_message_size_(-1) {}
 
   Call(grpc_call* call, CallHook* call_hook, CompletionQueue* cq,
-       int max_receive_message_size)
+       experimental::ClientRpcInfo* rpc_info)
       : call_hook_(call_hook),
         cq_(cq),
         call_(call),
-        max_receive_message_size_(max_receive_message_size) {}
+        max_receive_message_size_(-1),
+        client_rpc_info_(rpc_info) {}
+
+  Call(grpc_call* call, CallHook* call_hook, CompletionQueue* cq,
+       int max_receive_message_size, experimental::ServerRpcInfo* rpc_info)
+      : call_hook_(call_hook),
+        cq_(cq),
+        call_(call),
+        max_receive_message_size_(max_receive_message_size),
+        server_rpc_info_(rpc_info) {}
 
   void PerformOps(CallOpSetInterface* ops) {
     call_hook_->PerformOpsOnCall(ops, this);
@@ -690,11 +72,21 @@ class Call final {
 
   int max_receive_message_size() const { return max_receive_message_size_; }
 
+  experimental::ClientRpcInfo* client_rpc_info() const {
+    return client_rpc_info_;
+  }
+
+  experimental::ServerRpcInfo* server_rpc_info() const {
+    return server_rpc_info_;
+  }
+
  private:
   CallHook* call_hook_;
   CompletionQueue* cq_;
   grpc_call* call_;
   int max_receive_message_size_;
+  experimental::ClientRpcInfo* client_rpc_info_ = nullptr;
+  experimental::ServerRpcInfo* server_rpc_info_ = nullptr;
 };
 }  // namespace internal
 }  // namespace grpc

include/grpcpp/impl/codegen/call_op_set.h

@@ -0,0 +1,920 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_CALL_OP_SET_H
+#define GRPCPP_IMPL_CODEGEN_CALL_OP_SET_H
+
+#include <assert.h>
+#include <array>
+#include <cstring>
+#include <functional>
+#include <map>
+#include <memory>
+#include <vector>
+
+#include <grpcpp/impl/codegen/byte_buffer.h>
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/call_hook.h>
+#include <grpcpp/impl/codegen/call_op_set_interface.h>
+#include <grpcpp/impl/codegen/client_context.h>
+#include <grpcpp/impl/codegen/completion_queue_tag.h>
+#include <grpcpp/impl/codegen/config.h>
+#include <grpcpp/impl/codegen/core_codegen_interface.h>
+#include <grpcpp/impl/codegen/intercepted_channel.h>
+#include <grpcpp/impl/codegen/interceptor_common.h>
+#include <grpcpp/impl/codegen/serialization_traits.h>
+#include <grpcpp/impl/codegen/slice.h>
+#include <grpcpp/impl/codegen/string_ref.h>
+
+#include <grpc/impl/codegen/atm.h>
+#include <grpc/impl/codegen/compression_types.h>
+#include <grpc/impl/codegen/grpc_types.h>
+
+namespace grpc {
+
+class CompletionQueue;
+extern CoreCodegenInterface* g_core_codegen_interface;
+
+namespace internal {
+class Call;
+class CallHook;
+
+// TODO(yangg) if the map is changed before we send, the pointers will be a
+// mess. Make sure it does not happen.
+inline grpc_metadata* FillMetadataArray(
+    const std::multimap<grpc::string, grpc::string>& metadata,
+    size_t* metadata_count, const grpc::string& optional_error_details) {
+  *metadata_count = metadata.size() + (optional_error_details.empty() ? 0 : 1);
+  if (*metadata_count == 0) {
+    return nullptr;
+  }
+  grpc_metadata* metadata_array =
+      (grpc_metadata*)(g_core_codegen_interface->gpr_malloc(
+          (*metadata_count) * sizeof(grpc_metadata)));
+  size_t i = 0;
+  for (auto iter = metadata.cbegin(); iter != metadata.cend(); ++iter, ++i) {
+    metadata_array[i].key = SliceReferencingString(iter->first);
+    metadata_array[i].value = SliceReferencingString(iter->second);
+  }
+  if (!optional_error_details.empty()) {
+    metadata_array[i].key =
+        g_core_codegen_interface->grpc_slice_from_static_buffer(
+            kBinaryErrorDetailsKey, sizeof(kBinaryErrorDetailsKey) - 1);
+    metadata_array[i].value = SliceReferencingString(optional_error_details);
+  }
+  return metadata_array;
+}
+}  // namespace internal
+
+/// Per-message write options.
+class WriteOptions {
+ public:
+  WriteOptions() : flags_(0), last_message_(false) {}
+  WriteOptions(const WriteOptions& other)
+      : flags_(other.flags_), last_message_(other.last_message_) {}
+
+  /// Clear all flags.
+  inline void Clear() { flags_ = 0; }
+
+  /// Returns raw flags bitset.
+  inline uint32_t flags() const { return flags_; }
+
+  /// Sets flag for the disabling of compression for the next message write.
+  ///
+  /// \sa GRPC_WRITE_NO_COMPRESS
+  inline WriteOptions& set_no_compression() {
+    SetBit(GRPC_WRITE_NO_COMPRESS);
+    return *this;
+  }
+
+  /// Clears flag for the disabling of compression for the next message write.
+  ///
+  /// \sa GRPC_WRITE_NO_COMPRESS
+  inline WriteOptions& clear_no_compression() {
+    ClearBit(GRPC_WRITE_NO_COMPRESS);
+    return *this;
+  }
+
+  /// Get value for the flag indicating whether compression for the next
+  /// message write is forcefully disabled.
+  ///
+  /// \sa GRPC_WRITE_NO_COMPRESS
+  inline bool get_no_compression() const {
+    return GetBit(GRPC_WRITE_NO_COMPRESS);
+  }
+
+  /// Sets flag indicating that the write may be buffered and need not go out on
+  /// the wire immediately.
+  ///
+  /// \sa GRPC_WRITE_BUFFER_HINT
+  inline WriteOptions& set_buffer_hint() {
+    SetBit(GRPC_WRITE_BUFFER_HINT);
+    return *this;
+  }
+
+  /// Clears flag indicating that the write may be buffered and need not go out
+  /// on the wire immediately.
+  ///
+  /// \sa GRPC_WRITE_BUFFER_HINT
+  inline WriteOptions& clear_buffer_hint() {
+    ClearBit(GRPC_WRITE_BUFFER_HINT);
+    return *this;
+  }
+
+  /// Get value for the flag indicating that the write may be buffered and need
+  /// not go out on the wire immediately.
+  ///
+  /// \sa GRPC_WRITE_BUFFER_HINT
+  inline bool get_buffer_hint() const { return GetBit(GRPC_WRITE_BUFFER_HINT); }
+
+  /// corked bit: aliases set_buffer_hint currently, with the intent that
+  /// set_buffer_hint will be removed in the future
+  inline WriteOptions& set_corked() {
+    SetBit(GRPC_WRITE_BUFFER_HINT);
+    return *this;
+  }
+
+  inline WriteOptions& clear_corked() {
+    ClearBit(GRPC_WRITE_BUFFER_HINT);
+    return *this;
+  }
+
+  inline bool is_corked() const { return GetBit(GRPC_WRITE_BUFFER_HINT); }
+
+  /// last-message bit: indicates this is the last message in a stream
+  /// client-side:  makes Write the equivalent of performing Write, WritesDone
+  /// in a single step
+  /// server-side:  hold the Write until the service handler returns (sync api)
+  /// or until Finish is called (async api)
+  inline WriteOptions& set_last_message() {
+    last_message_ = true;
+    return *this;
+  }
+
+  /// Clears flag indicating that this is the last message in a stream,
+  /// disabling coalescing.
+  inline WriteOptions& clear_last_message() {
+    last_message_ = false;
+    return *this;
+  }
+
+  /// Guarantee that all bytes have been written to the socket before completing
+  /// this write (usually writes are completed when they pass flow control).
+  inline WriteOptions& set_write_through() {
+    SetBit(GRPC_WRITE_THROUGH);
+    return *this;
+  }
+
+  inline bool is_write_through() const { return GetBit(GRPC_WRITE_THROUGH); }
+
+  /// Get value for the flag indicating that this is the last message, and
+  /// should be coalesced with trailing metadata.
+  ///
+  /// \sa GRPC_WRITE_LAST_MESSAGE
+  bool is_last_message() const { return last_message_; }
+
+  WriteOptions& operator=(const WriteOptions& rhs) {
+    flags_ = rhs.flags_;
+    return *this;
+  }
+
+ private:
+  void SetBit(const uint32_t mask) { flags_ |= mask; }
+
+  void ClearBit(const uint32_t mask) { flags_ &= ~mask; }
+
+  bool GetBit(const uint32_t mask) const { return (flags_ & mask) != 0; }
+
+  uint32_t flags_;
+  bool last_message_;
+};
+
+namespace internal {
+
+/// Default argument for CallOpSet. I is unused by the class, but can be
+/// used for generating multiple names for the same thing.
+template <int I>
+class CallNoOp {
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {}
+  void FinishOp(bool* status) {}
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {}
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {}
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+  }
+};
+
+class CallOpSendInitialMetadata {
+ public:
+  CallOpSendInitialMetadata() : send_(false) {
+    maybe_compression_level_.is_set = false;
+  }
+
+  void SendInitialMetadata(std::multimap<grpc::string, grpc::string>* metadata,
+                           uint32_t flags) {
+    maybe_compression_level_.is_set = false;
+    send_ = true;
+    flags_ = flags;
+    metadata_map_ = metadata;
+  }
+
+  void set_compression_level(grpc_compression_level level) {
+    maybe_compression_level_.is_set = true;
+    maybe_compression_level_.level = level;
+  }
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (!send_ || hijacked_) return;
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_SEND_INITIAL_METADATA;
+    op->flags = flags_;
+    op->reserved = NULL;
+    initial_metadata_ =
+        FillMetadataArray(*metadata_map_, &initial_metadata_count_, "");
+    op->data.send_initial_metadata.count = initial_metadata_count_;
+    op->data.send_initial_metadata.metadata = initial_metadata_;
+    op->data.send_initial_metadata.maybe_compression_level.is_set =
+        maybe_compression_level_.is_set;
+    if (maybe_compression_level_.is_set) {
+      op->data.send_initial_metadata.maybe_compression_level.level =
+          maybe_compression_level_.level;
+    }
+  }
+  void FinishOp(bool* status) {
+    if (!send_ || hijacked_) return;
+    g_core_codegen_interface->gpr_free(initial_metadata_);
+    send_ = false;
+  }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (!send_) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_SEND_INITIAL_METADATA);
+    interceptor_methods->SetSendInitialMetadata(metadata_map_);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {}
+
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+  }
+
+  bool hijacked_ = false;
+  bool send_;
+  uint32_t flags_;
+  size_t initial_metadata_count_;
+  std::multimap<grpc::string, grpc::string>* metadata_map_;
+  grpc_metadata* initial_metadata_;
+  struct {
+    bool is_set;
+    grpc_compression_level level;
+  } maybe_compression_level_;
+};
+
+class CallOpSendMessage {
+ public:
+  CallOpSendMessage() : send_buf_() {}
+
+  /// Send \a message using \a options for the write. The \a options are cleared
+  /// after use.
+  template <class M>
+  Status SendMessage(const M& message,
+                     WriteOptions options) GRPC_MUST_USE_RESULT;
+
+  template <class M>
+  Status SendMessage(const M& message) GRPC_MUST_USE_RESULT;
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (!send_buf_.Valid() || hijacked_) return;
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_SEND_MESSAGE;
+    op->flags = write_options_.flags();
+    op->reserved = NULL;
+    op->data.send_message.send_message = send_buf_.c_buffer();
+    // Flags are per-message: clear them after use.
+    write_options_.Clear();
+  }
+  void FinishOp(bool* status) { send_buf_.Clear(); }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (!send_buf_.Valid()) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_SEND_MESSAGE);
+    interceptor_methods->SetSendMessage(&send_buf_);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {}
+
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+  }
+
+ private:
+  bool hijacked_ = false;
+  ByteBuffer send_buf_;
+  WriteOptions write_options_;
+};
+
+template <class M>
+Status CallOpSendMessage::SendMessage(const M& message, WriteOptions options) {
+  write_options_ = options;
+  bool own_buf;
+  // TODO(vjpai): Remove the void below when possible
+  // The void in the template parameter below should not be needed
+  // (since it should be implicit) but is needed due to an observed
+  // difference in behavior between clang and gcc for certain internal users
+  Status result = SerializationTraits<M, void>::Serialize(
+      message, send_buf_.bbuf_ptr(), &own_buf);
+  if (!own_buf) {
+    send_buf_.Duplicate();
+  }
+  return result;
+}
+
+template <class M>
+Status CallOpSendMessage::SendMessage(const M& message) {
+  return SendMessage(message, WriteOptions());
+}
+
+template <class R>
+class CallOpRecvMessage {
+ public:
+  CallOpRecvMessage()
+      : got_message(false),
+        message_(nullptr),
+        allow_not_getting_message_(false) {}
+
+  void RecvMessage(R* message) { message_ = message; }
+
+  // Do not change status if no message is received.
+  void AllowNoMessage() { allow_not_getting_message_ = true; }
+
+  bool got_message;
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (message_ == nullptr || hijacked_) return;
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_RECV_MESSAGE;
+    op->flags = 0;
+    op->reserved = NULL;
+    op->data.recv_message.recv_message = recv_buf_.c_buffer_ptr();
+  }
+
+  void FinishOp(bool* status) {
+    if (message_ == nullptr || hijacked_) return;
+    if (recv_buf_.Valid()) {
+      if (*status) {
+        got_message = *status =
+            SerializationTraits<R>::Deserialize(recv_buf_.bbuf_ptr(), message_)
+                .ok();
+        recv_buf_.Release();
+      } else {
+        got_message = false;
+        recv_buf_.Clear();
+      }
+    } else {
+      got_message = false;
+      if (!allow_not_getting_message_) {
+        *status = false;
+      }
+    }
+    message_ = nullptr;
+  }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    interceptor_methods->SetRecvMessage(message_);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (!got_message) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
+  }
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+    if (message_ == nullptr) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_RECV_MESSAGE);
+    got_message = true;
+  }
+
+ private:
+  R* message_;
+  ByteBuffer recv_buf_;
+  bool allow_not_getting_message_;
+  bool hijacked_ = false;
+};
+
+class DeserializeFunc {
+ public:
+  virtual Status Deserialize(ByteBuffer* buf) = 0;
+  virtual ~DeserializeFunc() {}
+};
+
+template <class R>
+class DeserializeFuncType final : public DeserializeFunc {
+ public:
+  DeserializeFuncType(R* message) : message_(message) {}
+  Status Deserialize(ByteBuffer* buf) override {
+    return SerializationTraits<R>::Deserialize(buf->bbuf_ptr(), message_);
+  }
+
+  ~DeserializeFuncType() override {}
+
+ private:
+  R* message_;  // Not a managed pointer because management is external to this
+};
+
+class CallOpGenericRecvMessage {
+ public:
+  CallOpGenericRecvMessage()
+      : got_message(false), allow_not_getting_message_(false) {}
+
+  template <class R>
+  void RecvMessage(R* message) {
+    // Use an explicit base class pointer to avoid resolution error in the
+    // following unique_ptr::reset for some old implementations.
+    DeserializeFunc* func = new DeserializeFuncType<R>(message);
+    deserialize_.reset(func);
+    message_ = message;
+  }
+
+  // Do not change status if no message is received.
+  void AllowNoMessage() { allow_not_getting_message_ = true; }
+
+  bool got_message;
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (!deserialize_ || hijacked_) return;
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_RECV_MESSAGE;
+    op->flags = 0;
+    op->reserved = NULL;
+    op->data.recv_message.recv_message = recv_buf_.c_buffer_ptr();
+  }
+
+  void FinishOp(bool* status) {
+    if (!deserialize_ || hijacked_) return;
+    if (recv_buf_.Valid()) {
+      if (*status) {
+        got_message = true;
+        *status = deserialize_->Deserialize(&recv_buf_).ok();
+        recv_buf_.Release();
+      } else {
+        got_message = false;
+        recv_buf_.Clear();
+      }
+    } else {
+      got_message = false;
+      if (!allow_not_getting_message_) {
+        *status = false;
+      }
+    }
+    deserialize_.reset();
+  }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    interceptor_methods->SetRecvMessage(message_);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (!got_message) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
+  }
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+    if (!deserialize_) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_RECV_MESSAGE);
+  }
+
+ private:
+  void* message_;
+  bool hijacked_ = false;
+  std::unique_ptr<DeserializeFunc> deserialize_;
+  ByteBuffer recv_buf_;
+  bool allow_not_getting_message_;
+};
+
+class CallOpClientSendClose {
+ public:
+  CallOpClientSendClose() : send_(false) {}
+
+  void ClientSendClose() { send_ = true; }
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (!send_ || hijacked_) return;
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+    op->flags = 0;
+    op->reserved = NULL;
+  }
+  void FinishOp(bool* status) { send_ = false; }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (!send_) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_SEND_CLOSE);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {}
+
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+  }
+
+ private:
+  bool hijacked_ = false;
+  bool send_;
+};
+
+class CallOpServerSendStatus {
+ public:
+  CallOpServerSendStatus() : send_status_available_(false) {}
+
+  void ServerSendStatus(
+      std::multimap<grpc::string, grpc::string>* trailing_metadata,
+      const Status& status) {
+    send_error_details_ = status.error_details();
+    metadata_map_ = trailing_metadata;
+    send_status_available_ = true;
+    send_status_code_ = static_cast<grpc_status_code>(status.error_code());
+    send_error_message_ = status.error_message();
+  }
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (!send_status_available_ || hijacked_) return;
+    trailing_metadata_ = FillMetadataArray(
+        *metadata_map_, &trailing_metadata_count_, send_error_details_);
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
+    op->data.send_status_from_server.trailing_metadata_count =
+        trailing_metadata_count_;
+    op->data.send_status_from_server.trailing_metadata = trailing_metadata_;
+    op->data.send_status_from_server.status = send_status_code_;
+    error_message_slice_ = SliceReferencingString(send_error_message_);
+    op->data.send_status_from_server.status_details =
+        send_error_message_.empty() ? nullptr : &error_message_slice_;
+    op->flags = 0;
+    op->reserved = NULL;
+  }
+
+  void FinishOp(bool* status) {
+    if (!send_status_available_ || hijacked_) return;
+    g_core_codegen_interface->gpr_free(trailing_metadata_);
+    send_status_available_ = false;
+  }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (!send_status_available_) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_SEND_STATUS);
+    interceptor_methods->SetSendTrailingMetadata(metadata_map_);
+    interceptor_methods->SetSendStatus(&send_status_code_, &send_error_details_,
+                                       &send_error_message_);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {}
+
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+  }
+
+ private:
+  bool hijacked_ = false;
+  bool send_status_available_;
+  grpc_status_code send_status_code_;
+  grpc::string send_error_details_;
+  grpc::string send_error_message_;
+  size_t trailing_metadata_count_;
+  std::multimap<grpc::string, grpc::string>* metadata_map_;
+  grpc_metadata* trailing_metadata_;
+  grpc_slice error_message_slice_;
+};
+
+class CallOpRecvInitialMetadata {
+ public:
+  CallOpRecvInitialMetadata() : metadata_map_(nullptr) {}
+
+  void RecvInitialMetadata(ClientContext* context) {
+    context->initial_metadata_received_ = true;
+    metadata_map_ = &context->recv_initial_metadata_;
+  }
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (metadata_map_ == nullptr || hijacked_) return;
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_RECV_INITIAL_METADATA;
+    op->data.recv_initial_metadata.recv_initial_metadata = metadata_map_->arr();
+    op->flags = 0;
+    op->reserved = NULL;
+  }
+
+  void FinishOp(bool* status) {
+    if (metadata_map_ == nullptr || hijacked_) return;
+  }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    interceptor_methods->SetRecvInitialMetadata(metadata_map_);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (metadata_map_ == nullptr) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::POST_RECV_INITIAL_METADATA);
+    metadata_map_ = nullptr;
+  }
+
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+    if (metadata_map_ == nullptr) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_RECV_INITIAL_METADATA);
+  }
+
+ private:
+  bool hijacked_ = false;
+  MetadataMap* metadata_map_;
+};
+
+class CallOpClientRecvStatus {
+ public:
+  CallOpClientRecvStatus()
+      : recv_status_(nullptr), debug_error_string_(nullptr) {}
+
+  void ClientRecvStatus(ClientContext* context, Status* status) {
+    client_context_ = context;
+    metadata_map_ = &client_context_->trailing_metadata_;
+    recv_status_ = status;
+    error_message_ = g_core_codegen_interface->grpc_empty_slice();
+  }
+
+ protected:
+  void AddOp(grpc_op* ops, size_t* nops) {
+    if (recv_status_ == nullptr || hijacked_) return;
+    grpc_op* op = &ops[(*nops)++];
+    op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
+    op->data.recv_status_on_client.trailing_metadata = metadata_map_->arr();
+    op->data.recv_status_on_client.status = &status_code_;
+    op->data.recv_status_on_client.status_details = &error_message_;
+    op->data.recv_status_on_client.error_string = &debug_error_string_;
+    op->flags = 0;
+    op->reserved = NULL;
+  }
+
+  void FinishOp(bool* status) {
+    if (recv_status_ == nullptr || hijacked_) return;
+    grpc::string binary_error_details = metadata_map_->GetBinaryErrorDetails();
+    *recv_status_ =
+        Status(static_cast<StatusCode>(status_code_),
+               GRPC_SLICE_IS_EMPTY(error_message_)
+                   ? grpc::string()
+                   : grpc::string(GRPC_SLICE_START_PTR(error_message_),
+                                  GRPC_SLICE_END_PTR(error_message_)),
+               binary_error_details);
+    client_context_->set_debug_error_string(
+        debug_error_string_ != nullptr ? debug_error_string_ : "");
+    g_core_codegen_interface->grpc_slice_unref(error_message_);
+    if (debug_error_string_ != nullptr) {
+      g_core_codegen_interface->gpr_free((void*)debug_error_string_);
+    }
+  }
+
+  void SetInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    interceptor_methods->SetRecvStatus(recv_status_);
+    interceptor_methods->SetRecvTrailingMetadata(metadata_map_);
+  }
+
+  void SetFinishInterceptionHookPoint(
+      InternalInterceptorBatchMethods* interceptor_methods) {
+    if (recv_status_ == nullptr) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::POST_RECV_STATUS);
+    recv_status_ = nullptr;
+  }
+
+  void SetHijackingState(InternalInterceptorBatchMethods* interceptor_methods) {
+    hijacked_ = true;
+    if (recv_status_ == nullptr) return;
+    interceptor_methods->AddInterceptionHookPoint(
+        experimental::InterceptionHookPoints::PRE_RECV_STATUS);
+  }
+
+ private:
+  bool hijacked_ = false;
+  ClientContext* client_context_;
+  MetadataMap* metadata_map_;
+  Status* recv_status_;
+  const char* debug_error_string_;
+  grpc_status_code status_code_;
+  grpc_slice error_message_;
+};
+
+template <class Op1 = CallNoOp<1>, class Op2 = CallNoOp<2>,
+          class Op3 = CallNoOp<3>, class Op4 = CallNoOp<4>,
+          class Op5 = CallNoOp<5>, class Op6 = CallNoOp<6>>
+class CallOpSet;
+
+/// Primary implementation of CallOpSetInterface.
+/// Since we cannot use variadic templates, we declare slots up to
+/// the maximum count of ops we'll need in a set. We leverage the
+/// empty base class optimization to slim this class (especially
+/// when there are many unused slots used). To avoid duplicate base classes,
+/// the template parmeter for CallNoOp is varied by argument position.
+template <class Op1, class Op2, class Op3, class Op4, class Op5, class Op6>
+class CallOpSet : public CallOpSetInterface,
+                  public Op1,
+                  public Op2,
+                  public Op3,
+                  public Op4,
+                  public Op5,
+                  public Op6 {
+ public:
+  CallOpSet() : core_cq_tag_(this), return_tag_(this) {}
+  // The copy constructor and assignment operator reset the value of
+  // core_cq_tag_, return_tag_, done_intercepting_ and interceptor_methods_
+  // since those are only meaningful on a specific object, not across objects.
+  CallOpSet(const CallOpSet& other)
+      : core_cq_tag_(this),
+        return_tag_(this),
+        call_(other.call_),
+        done_intercepting_(false),
+        interceptor_methods_(InterceptorBatchMethodsImpl()) {}
+
+  CallOpSet& operator=(const CallOpSet& other) {
+    core_cq_tag_ = this;
+    return_tag_ = this;
+    call_ = other.call_;
+    done_intercepting_ = false;
+    interceptor_methods_ = InterceptorBatchMethodsImpl();
+    return *this;
+  }
+
+  void FillOps(Call* call) override {
+    done_intercepting_ = false;
+    g_core_codegen_interface->grpc_call_ref(call->call());
+    call_ =
+        *call;  // It's fine to create a copy of call since it's just pointers
+
+    if (RunInterceptors()) {
+      ContinueFillOpsAfterInterception();
+    } else {
+      // After the interceptors are run, ContinueFillOpsAfterInterception will
+      // be run
+    }
+  }
+
+  bool FinalizeResult(void** tag, bool* status) override {
+    if (done_intercepting_) {
+      // We have already finished intercepting and filling in the results. This
+      // round trip from the core needed to be made because interceptors were
+      // run
+      *tag = return_tag_;
+      *status = saved_status_;
+      g_core_codegen_interface->grpc_call_unref(call_.call());
+      return true;
+    }
+
+    this->Op1::FinishOp(status);
+    this->Op2::FinishOp(status);
+    this->Op3::FinishOp(status);
+    this->Op4::FinishOp(status);
+    this->Op5::FinishOp(status);
+    this->Op6::FinishOp(status);
+    saved_status_ = *status;
+    if (RunInterceptorsPostRecv()) {
+      *tag = return_tag_;
+      g_core_codegen_interface->grpc_call_unref(call_.call());
+      return true;
+    }
+    // Interceptors are going to be run, so we can't return the tag just yet.
+    // After the interceptors are run, ContinueFinalizeResultAfterInterception
+    return false;
+  }
+
+  void set_output_tag(void* return_tag) { return_tag_ = return_tag; }
+
+  void* core_cq_tag() override { return core_cq_tag_; }
+
+  /// set_core_cq_tag is used to provide a different core CQ tag than "this".
+  /// This is used for callback-based tags, where the core tag is the core
+  /// callback function. It does not change the use or behavior of any other
+  /// function (such as FinalizeResult)
+  void set_core_cq_tag(void* core_cq_tag) { core_cq_tag_ = core_cq_tag; }
+
+  // This will be called while interceptors are run if the RPC is a hijacked
+  // RPC. This should set hijacking state for each of the ops.
+  void SetHijackingState() override {
+    this->Op1::SetHijackingState(&interceptor_methods_);
+    this->Op2::SetHijackingState(&interceptor_methods_);
+    this->Op3::SetHijackingState(&interceptor_methods_);
+    this->Op4::SetHijackingState(&interceptor_methods_);
+    this->Op5::SetHijackingState(&interceptor_methods_);
+    this->Op6::SetHijackingState(&interceptor_methods_);
+  }
+
+  // Should be called after interceptors are done running
+  void ContinueFillOpsAfterInterception() override {
+    static const size_t MAX_OPS = 6;
+    grpc_op ops[MAX_OPS];
+    size_t nops = 0;
+    this->Op1::AddOp(ops, &nops);
+    this->Op2::AddOp(ops, &nops);
+    this->Op3::AddOp(ops, &nops);
+    this->Op4::AddOp(ops, &nops);
+    this->Op5::AddOp(ops, &nops);
+    this->Op6::AddOp(ops, &nops);
+    GPR_CODEGEN_ASSERT(GRPC_CALL_OK ==
+                       g_core_codegen_interface->grpc_call_start_batch(
+                           call_.call(), ops, nops, core_cq_tag(), nullptr));
+  }
+
+  // Should be called after interceptors are done running on the finalize result
+  // path
+  void ContinueFinalizeResultAfterInterception() override {
+    done_intercepting_ = true;
+    GPR_CODEGEN_ASSERT(GRPC_CALL_OK ==
+                       g_core_codegen_interface->grpc_call_start_batch(
+                           call_.call(), nullptr, 0, core_cq_tag(), nullptr));
+  }
+
+ private:
+  // Returns true if no interceptors need to be run
+  bool RunInterceptors() {
+    interceptor_methods_.ClearState();
+    interceptor_methods_.SetCallOpSetInterface(this);
+    interceptor_methods_.SetCall(&call_);
+    this->Op1::SetInterceptionHookPoint(&interceptor_methods_);
+    this->Op2::SetInterceptionHookPoint(&interceptor_methods_);
+    this->Op3::SetInterceptionHookPoint(&interceptor_methods_);
+    this->Op4::SetInterceptionHookPoint(&interceptor_methods_);
+    this->Op5::SetInterceptionHookPoint(&interceptor_methods_);
+    this->Op6::SetInterceptionHookPoint(&interceptor_methods_);
+    return interceptor_methods_.RunInterceptors();
+  }
+  // Returns true if no interceptors need to be run
+  bool RunInterceptorsPostRecv() {
+    // Call and OpSet had already been set on the set state.
+    // SetReverse also clears previously set hook points
+    interceptor_methods_.SetReverse();
+    this->Op1::SetFinishInterceptionHookPoint(&interceptor_methods_);
+    this->Op2::SetFinishInterceptionHookPoint(&interceptor_methods_);
+    this->Op3::SetFinishInterceptionHookPoint(&interceptor_methods_);
+    this->Op4::SetFinishInterceptionHookPoint(&interceptor_methods_);
+    this->Op5::SetFinishInterceptionHookPoint(&interceptor_methods_);
+    this->Op6::SetFinishInterceptionHookPoint(&interceptor_methods_);
+    return interceptor_methods_.RunInterceptors();
+  }
+
+  void* core_cq_tag_;
+  void* return_tag_;
+  Call call_;
+  bool done_intercepting_ = false;
+  InterceptorBatchMethodsImpl interceptor_methods_;
+  bool saved_status_;
+};
+
+}  // namespace internal
+}  // namespace grpc
+
+#endif  // GRPCPP_IMPL_CODEGEN_CALL_OP_SET_H

include/grpcpp/impl/codegen/call_op_set_interface.h

@@ -0,0 +1,59 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_CALL_OP_SET_INTERFACE_H
+#define GRPCPP_IMPL_CODEGEN_CALL_OP_SET_INTERFACE_H
+
+#include <grpcpp/impl/codegen/completion_queue_tag.h>
+
+namespace grpc {
+namespace internal {
+
+class Call;
+
+/// An abstract collection of call ops, used to generate the
+/// grpc_call_op structure to pass down to the lower layers,
+/// and as it is-a CompletionQueueTag, also massages the final
+/// completion into the correct form for consumption in the C++
+/// API.
+class CallOpSetInterface : public CompletionQueueTag {
+ public:
+  /// Fills in grpc_op, starting from ops[*nops] and moving
+  /// upwards.
+  virtual void FillOps(internal::Call* call) = 0;
+
+  /// Get the tag to be used at the core completion queue. Generally, the
+  /// value of core_cq_tag will be "this". However, it can be overridden if we
+  /// want core to process the tag differently (e.g., as a core callback)
+  virtual void* core_cq_tag() = 0;
+
+  // This will be called while interceptors are run if the RPC is a hijacked
+  // RPC. This should set hijacking state for each of the ops.
+  virtual void SetHijackingState() = 0;
+
+  // Should be called after interceptors are done running
+  virtual void ContinueFillOpsAfterInterception() = 0;
+
+  // Should be called after interceptors are done running on the finalize result
+  // path
+  virtual void ContinueFinalizeResultAfterInterception() = 0;
+};
+}  // namespace internal
+}  // namespace grpc
+
+#endif  // GRPCPP_IMPL_CODEGEN_CALL_OP_SET_INTERFACE_H

include/grpcpp/impl/codegen/callback_common.h

@@ -32,16 +32,16 @@ namespace grpc {
 namespace internal {
 
 /// An exception-safe way of invoking a user-specified callback function
-template <class Func, class Arg>
-void CatchingCallback(Func&& func, Arg&& arg) {
+template <class Func, class... Args>
+void CatchingCallback(Func&& func, Args&&... args) {
 #if GRPC_ALLOW_EXCEPTIONS
   try {
-    func(arg);
+    func(std::forward<Args>(args)...);
   } catch (...) {
     // nothing to return or change here, just don't crash the library
   }
 #else   // GRPC_ALLOW_EXCEPTIONS
-  func(arg);
+  func(std::forward<Args>(args)...);
 #endif  // GRPC_ALLOW_EXCEPTIONS
 }
 
@@ -94,14 +94,18 @@ class CallbackWithStatusTag
   void Run(bool ok) {
     void* ignored = ops_;
 
-    GPR_CODEGEN_ASSERT(ops_->FinalizeResult(&ignored, &ok));
+    if (!ops_->FinalizeResult(&ignored, &ok)) {
+      // The tag was swallowed
+      return;
+    }
     GPR_CODEGEN_ASSERT(ignored == ops_);
 
     // Last use of func_ or status_, so ok to move them out
-    CatchingCallback(std::move(func_), std::move(status_));
-
+    auto func = std::move(func_);
+    auto status = std::move(status_);
     func_ = nullptr;     // reset to clear this out for sure
     status_ = Status();  // reset to clear this out for sure
+    CatchingCallback(std::move(func), std::move(status));
     g_core_codegen_interface->grpc_call_unref(call_);
   }
 };
@@ -121,6 +125,8 @@ class CallbackWithSuccessTag
   // there are no tests catching the compiler warning.
   static void operator delete(void*, void*) { assert(0); }
 
+  CallbackWithSuccessTag() : call_(nullptr), ops_(nullptr) {}
+
   CallbackWithSuccessTag(grpc_call* call, std::function<void(bool)> f,
                          CompletionQueueTag* ops)
       : call_(call), func_(std::move(f)), ops_(ops) {
@@ -135,6 +141,9 @@ class CallbackWithSuccessTag
   // that are detected before the operations are internally processed.
   void force_run(bool ok) { Run(ok); }
 
+  /// check if this tag has ever been set
+  operator bool() const { return call_ != nullptr; }
+
  private:
   grpc_call* call_;
   std::function<void(bool)> func_;
@@ -147,13 +156,19 @@ class CallbackWithSuccessTag
   void Run(bool ok) {
     void* ignored = ops_;
     bool new_ok = ok;
-    GPR_CODEGEN_ASSERT(ops_->FinalizeResult(&ignored, &new_ok));
+    // Allow a "false" return value from FinalizeResult to silence the
+    // callback, just as it silences a CQ tag in the async cases
+    bool do_callback = ops_->FinalizeResult(&ignored, &new_ok);
     GPR_CODEGEN_ASSERT(ignored == ops_);
 
-    // Last use of func_, so ok to move it out for rvalue call above
-    CatchingCallback(std::move(func_), ok);
-
-    func_ = nullptr;  // reset to clear this out for sure
+    if (do_callback) {
+      // Last use of func_, so ok to move it out for rvalue call above
+      auto func = std::move(func_);
+      func_ = nullptr;  // reset to clear this out for sure
+      CatchingCallback(std::move(func), ok);
+    } else {
+      func_ = nullptr;  // reset to clear this out for sure
+    }
     g_core_codegen_interface->grpc_call_unref(call_);
   }
 };

include/grpcpp/impl/codegen/channel_interface.h

@@ -20,6 +20,8 @@
 #define GRPCPP_IMPL_CODEGEN_CHANNEL_INTERFACE_H
 
 #include <grpc/impl/codegen/connectivity_state.h>
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/client_context.h>
 #include <grpcpp/impl/codegen/status.h>
 #include <grpcpp/impl/codegen/time.h>
 
@@ -51,6 +53,7 @@ template <class W, class R>
 class ClientAsyncReaderWriterFactory;
 template <class R>
 class ClientAsyncResponseReaderFactory;
+class InterceptedChannel;
 }  // namespace internal
 
 /// Codegen interface for \a grpc::Channel.
@@ -108,6 +111,7 @@ class ChannelInterface {
   template <class InputMessage, class OutputMessage>
   friend class ::grpc::internal::CallbackUnaryCallImpl;
   friend class ::grpc::internal::RpcMethod;
+  friend class ::grpc::internal::InterceptedChannel;
   virtual internal::Call CreateCall(const internal::RpcMethod& method,
                                     ClientContext* context,
                                     CompletionQueue* cq) = 0;
@@ -120,12 +124,26 @@ class ChannelInterface {
   virtual bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
                                       gpr_timespec deadline) = 0;
 
+  // EXPERIMENTAL
+  // This is needed to keep codegen_test_minimal happy. InterceptedChannel needs
+  // to make use of this but can't directly call Channel's implementation
+  // because of the test.
+  // Returns an empty Call object (rather than being pure) since this is a new
+  // method and adding a new pure method to an interface would be a breaking
+  // change (even though this is private and non-API)
+  virtual internal::Call CreateCallInternal(const internal::RpcMethod& method,
+                                            ClientContext* context,
+                                            CompletionQueue* cq,
+                                            int interceptor_pos) {
+    return internal::Call();
+  }
+
   // EXPERIMENTAL
   // A method to get the callbackable completion queue associated with this
   // channel. If the return value is nullptr, this channel doesn't support
   // callback operations.
   // TODO(vjpai): Consider a better default like using a global CQ
-  // Returns nullptr (rather than being pure) since this is a new method
+  // Returns nullptr (rather than being pure) since this is a post-1.0 method
   // and adding a new pure method to an interface would be a breaking change
   // (even though this is private and non-API)
   virtual CompletionQueue* CallbackCQ() { return nullptr; }

include/grpcpp/impl/codegen/client_callback.h

@@ -77,14 +77,14 @@ class CallbackUnaryCallImpl {
       tag->force_run(s);
       return;
     }
-    ops->SendInitialMetadata(context->send_initial_metadata_,
+    ops->SendInitialMetadata(&context->send_initial_metadata_,
                              context->initial_metadata_flags());
     ops->RecvInitialMetadata(context);
     ops->RecvMessage(result);
     ops->AllowNoMessage();
     ops->ClientSendClose();
     ops->ClientRecvStatus(context, tag->status_ptr());
-    ops->set_cq_tag(tag);
+    ops->set_core_cq_tag(tag);
     call.PerformOps(ops);
   }
 };

include/grpcpp/impl/codegen/client_context.h

@@ -41,6 +41,7 @@
 
 #include <grpc/impl/codegen/compression_types.h>
 #include <grpc/impl/codegen/propagation_bits.h>
+#include <grpcpp/impl/codegen/client_interceptor.h>
 #include <grpcpp/impl/codegen/config.h>
 #include <grpcpp/impl/codegen/core_codegen_interface.h>
 #include <grpcpp/impl/codegen/create_auth_context.h>
@@ -402,6 +403,17 @@ class ClientContext {
   grpc_call* call() const { return call_; }
   void set_call(grpc_call* call, const std::shared_ptr<Channel>& channel);
 
+  experimental::ClientRpcInfo* set_client_rpc_info(
+      const char* method, grpc::ChannelInterface* channel,
+      const std::vector<
+          std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>&
+          creators,
+      size_t interceptor_pos) {
+    rpc_info_ = experimental::ClientRpcInfo(this, method, channel);
+    rpc_info_.RegisterInterceptors(creators, interceptor_pos);
+    return &rpc_info_;
+  }
+
   uint32_t initial_metadata_flags() const {
     return (idempotent_ ? GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST : 0) |
            (wait_for_ready_ ? GRPC_INITIAL_METADATA_WAIT_FOR_READY : 0) |
@@ -439,6 +451,8 @@ class ClientContext {
   bool initial_metadata_corked_;
 
   grpc::string debug_error_string_;
+
+  experimental::ClientRpcInfo rpc_info_;
 };
 
 }  // namespace grpc

include/grpcpp/impl/codegen/client_interceptor.h

@@ -19,23 +19,75 @@
 #ifndef GRPCPP_IMPL_CODEGEN_CLIENT_INTERCEPTOR_H
 #define GRPCPP_IMPL_CODEGEN_CLIENT_INTERCEPTOR_H
 
+#include <vector>
+
 #include <grpcpp/impl/codegen/interceptor.h>
+#include <grpcpp/impl/codegen/string_ref.h>
 
 namespace grpc {
-namespace experimental {
-class ClientInterceptor {
- public:
-  virtual ~ClientInterceptor() {}
 
-  virtual void Intercept(InterceptorBatchMethods* methods) = 0;
-};
+class ClientContext;
+class Channel;
 
-class ClientRpcInfo {};
+namespace internal {
+class InterceptorBatchMethodsImpl;
+}
+
+namespace experimental {
+class ClientRpcInfo;
 
 class ClientInterceptorFactoryInterface {
  public:
   virtual ~ClientInterceptorFactoryInterface() {}
-  virtual ClientInterceptor* CreateClientInterceptor(ClientRpcInfo* info) = 0;
+  virtual Interceptor* CreateClientInterceptor(ClientRpcInfo* info) = 0;
+};
+
+class ClientRpcInfo {
+ public:
+  ClientRpcInfo() {}
+
+  ~ClientRpcInfo(){};
+
+  ClientRpcInfo(const ClientRpcInfo&) = delete;
+  ClientRpcInfo(ClientRpcInfo&&) = default;
+  ClientRpcInfo& operator=(ClientRpcInfo&&) = default;
+
+  // Getter methods
+  const char* method() { return method_; }
+  ChannelInterface* channel() { return channel_; }
+  grpc::ClientContext* client_context() { return ctx_; }
+
+ private:
+  ClientRpcInfo(grpc::ClientContext* ctx, const char* method,
+                grpc::ChannelInterface* channel)
+      : ctx_(ctx), method_(method), channel_(channel) {}
+  // Runs interceptor at pos \a pos.
+  void RunInterceptor(
+      experimental::InterceptorBatchMethods* interceptor_methods, size_t pos) {
+    GPR_CODEGEN_ASSERT(pos < interceptors_.size());
+    interceptors_[pos]->Intercept(interceptor_methods);
+  }
+
+  void RegisterInterceptors(
+      const std::vector<std::unique_ptr<
+          experimental::ClientInterceptorFactoryInterface>>& creators,
+      int interceptor_pos) {
+    for (auto it = creators.begin() + interceptor_pos; it != creators.end();
+         ++it) {
+      interceptors_.push_back(std::unique_ptr<experimental::Interceptor>(
+          (*it)->CreateClientInterceptor(this)));
+    }
+  }
+
+  grpc::ClientContext* ctx_ = nullptr;
+  const char* method_ = nullptr;
+  grpc::ChannelInterface* channel_ = nullptr;
+  std::vector<std::unique_ptr<experimental::Interceptor>> interceptors_;
+  bool hijacked_ = false;
+  size_t hijacked_interceptor_ = 0;
+
+  friend class internal::InterceptorBatchMethodsImpl;
+  friend class grpc::ClientContext;
 };
 
 }  // namespace experimental

include/grpcpp/impl/codegen/client_unary_call.h

@@ -61,7 +61,7 @@ class BlockingUnaryCallImpl {
     if (!status_.ok()) {
       return;
     }
-    ops.SendInitialMetadata(context->send_initial_metadata_,
+    ops.SendInitialMetadata(&context->send_initial_metadata_,
                             context->initial_metadata_flags());
     ops.RecvInitialMetadata(context);
     ops.RecvMessage(result);

include/grpcpp/impl/codegen/completion_queue.h

@@ -122,8 +122,8 @@ class CompletionQueue : private GrpcLibraryCodegen {
   /// Read from the queue, blocking until an event is available or the queue is
   /// shutting down.
   ///
-  /// \param tag[out] Updated to point to the read event's tag.
-  /// \param ok[out] true if read a successful event, false otherwise.
+  /// \param tag [out] Updated to point to the read event's tag.
+  /// \param ok [out] true if read a successful event, false otherwise.
   ///
   /// Note that each tag sent to the completion queue (through RPC operations
   /// or alarms) will be delivered out of the completion queue by a call to
@@ -178,10 +178,10 @@ class CompletionQueue : private GrpcLibraryCodegen {
   /// within the \a deadline).  A \a tag points to an arbitrary location usually
   /// employed to uniquely identify an event.
   ///
-  /// \param tag[out] Upon sucess, updated to point to the event's tag.
-  /// \param ok[out] Upon sucess, true if a successful event, false otherwise
+  /// \param tag [out] Upon sucess, updated to point to the event's tag.
+  /// \param ok [out] Upon sucess, true if a successful event, false otherwise
   ///        See documentation for CompletionQueue::Next for explanation of ok
-  /// \param deadline[in] How long to block in wait for an event.
+  /// \param deadline [in] How long to block in wait for an event.
   ///
   /// \return The type of event read.
   template <typename T>
@@ -197,10 +197,11 @@ class CompletionQueue : private GrpcLibraryCodegen {
   /// within the \a deadline).  A \a tag points to an arbitrary location usually
   /// employed to uniquely identify an event.
   ///
-  /// \param F[in] Function to execute before calling AsyncNext on this queue.
-  /// \param tag[out] Upon sucess, updated to point to the event's tag.
-  /// \param ok[out] Upon sucess, true if read a regular event, false otherwise.
-  /// \param deadline[in] How long to block in wait for an event.
+  /// \param f [in] Function to execute before calling AsyncNext on this queue.
+  /// \param tag [out] Upon sucess, updated to point to the event's tag.
+  /// \param ok [out] Upon sucess, true if read a regular event, false
+  /// otherwise.
+  /// \param deadline [in] How long to block in wait for an event.
   ///
   /// \return The type of event read.
   template <typename T, typename F>
@@ -299,14 +300,17 @@ class CompletionQueue : private GrpcLibraryCodegen {
   bool Pluck(internal::CompletionQueueTag* tag) {
     auto deadline =
         g_core_codegen_interface->gpr_inf_future(GPR_CLOCK_REALTIME);
-    auto ev = g_core_codegen_interface->grpc_completion_queue_pluck(
-        cq_, tag, deadline, nullptr);
-    bool ok = ev.success != 0;
-    void* ignored = tag;
-    GPR_CODEGEN_ASSERT(tag->FinalizeResult(&ignored, &ok));
-    GPR_CODEGEN_ASSERT(ignored == tag);
-    // Ignore mutations by FinalizeResult: Pluck returns the C API status
-    return ev.success != 0;
+    while (true) {
+      auto ev = g_core_codegen_interface->grpc_completion_queue_pluck(
+          cq_, tag, deadline, nullptr);
+      bool ok = ev.success != 0;
+      void* ignored = tag;
+      if (tag->FinalizeResult(&ignored, &ok)) {
+        GPR_CODEGEN_ASSERT(ignored == tag);
+        // Ignore mutations by FinalizeResult: Pluck returns the C API status
+        return ev.success != 0;
+      }
+    }
   }
 
   /// Performs a single polling pluck on \a tag.
@@ -376,17 +380,23 @@ class ServerCompletionQueue : public CompletionQueue {
   ServerCompletionQueue() : polling_type_(GRPC_CQ_DEFAULT_POLLING) {}
 
  private:
-  /// \param is_frequently_polled Informs the GRPC library about whether the
-  /// server completion queue would be actively polled (by calling Next() or
-  /// AsyncNext()). By default all server completion queues are assumed to be
-  /// frequently polled.
-  ServerCompletionQueue(grpc_cq_polling_type polling_type)
+  /// \param completion_type indicates whether this is a NEXT or CALLBACK
+  /// completion queue.
+  /// \param polling_type Informs the GRPC library about the type of polling
+  /// allowed on this completion queue. See grpc_cq_polling_type's description
+  /// in grpc_types.h for more details.
+  /// \param shutdown_cb is the shutdown callback used for CALLBACK api queues
+  ServerCompletionQueue(grpc_cq_completion_type completion_type,
+                        grpc_cq_polling_type polling_type,
+                        grpc_experimental_completion_queue_functor* shutdown_cb)
       : CompletionQueue(grpc_completion_queue_attributes{
-            GRPC_CQ_CURRENT_VERSION, GRPC_CQ_NEXT, polling_type, nullptr}),
+            GRPC_CQ_CURRENT_VERSION, completion_type, polling_type,
+            shutdown_cb}),
         polling_type_(polling_type) {}
 
   grpc_cq_polling_type polling_type_;
   friend class ServerBuilder;
+  friend class Server;
 };
 
 }  // namespace grpc

include/grpcpp/impl/codegen/config_protobuf.h

@@ -66,6 +66,12 @@
 #define GRPC_CUSTOM_CODEDINPUTSTREAM ::google::protobuf::io::CodedInputStream
 #endif
 
+#ifndef GRPC_CUSTOM_JSONUTIL
+#include <google/protobuf/util/json_util.h>
+#define GRPC_CUSTOM_JSONUTIL ::google::protobuf::util
+#define GRPC_CUSTOM_UTIL_STATUS ::google::protobuf::util::Status
+#endif
+
 namespace grpc {
 namespace protobuf {
 
@@ -83,6 +89,12 @@ typedef GRPC_CUSTOM_SERVICEDESCRIPTOR ServiceDescriptor;
 typedef GRPC_CUSTOM_SIMPLEDESCRIPTORDATABASE SimpleDescriptorDatabase;
 typedef GRPC_CUSTOM_SOURCELOCATION SourceLocation;
 
+namespace util {
+typedef GRPC_CUSTOM_UTIL_STATUS Status;
+}  // namespace util
+
+namespace json = GRPC_CUSTOM_JSONUTIL;
+
 namespace io {
 typedef GRPC_CUSTOM_ZEROCOPYOUTPUTSTREAM ZeroCopyOutputStream;
 typedef GRPC_CUSTOM_ZEROCOPYINPUTSTREAM ZeroCopyInputStream;

include/grpcpp/impl/codegen/core_codegen.h

@@ -63,6 +63,9 @@ class CoreCodegen final : public CoreCodegenInterface {
   void gpr_cv_signal(gpr_cv* cv) override;
   void gpr_cv_broadcast(gpr_cv* cv) override;
 
+  grpc_call_error grpc_call_start_batch(grpc_call* call, const grpc_op* ops,
+                                        size_t nops, void* tag,
+                                        void* reserved) override;
   grpc_call_error grpc_call_cancel_with_status(grpc_call* call,
                                                grpc_status_code status,
                                                const char* description,

include/grpcpp/impl/codegen/core_codegen_interface.h

@@ -100,6 +100,9 @@ class CoreCodegenInterface {
   virtual grpc_slice grpc_slice_new_with_len(void* p, size_t len,
                                              void (*destroy)(void*,
                                                              size_t)) = 0;
+  virtual grpc_call_error grpc_call_start_batch(grpc_call* call,
+                                                const grpc_op* ops, size_t nops,
+                                                void* tag, void* reserved) = 0;
   virtual grpc_call_error grpc_call_cancel_with_status(grpc_call* call,
                                                        grpc_status_code status,
                                                        const char* description,

include/grpcpp/impl/codegen/intercepted_channel.h

@@ -0,0 +1,80 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_INTERCEPTED_CHANNEL_H
+#define GRPCPP_IMPL_CODEGEN_INTERCEPTED_CHANNEL_H
+
+#include <grpcpp/impl/codegen/channel_interface.h>
+
+namespace grpc {
+
+namespace internal {
+
+class InterceptorBatchMethodsImpl;
+
+/// An InterceptedChannel is available to client Interceptors. An
+/// InterceptedChannel is unique to an interceptor, and when an RPC is started
+/// on this channel, only those interceptors that come after this interceptor
+/// see the RPC.
+class InterceptedChannel : public ChannelInterface {
+ public:
+  virtual ~InterceptedChannel() { channel_ = nullptr; }
+
+  /// Get the current channel state. If the channel is in IDLE and
+  /// \a try_to_connect is set to true, try to connect.
+  grpc_connectivity_state GetState(bool try_to_connect) override {
+    return channel_->GetState(try_to_connect);
+  }
+
+ private:
+  InterceptedChannel(ChannelInterface* channel, int pos)
+      : channel_(channel), interceptor_pos_(pos) {}
+
+  Call CreateCall(const RpcMethod& method, ClientContext* context,
+                  CompletionQueue* cq) override {
+    return channel_->CreateCallInternal(method, context, cq, interceptor_pos_);
+  }
+
+  void PerformOpsOnCall(CallOpSetInterface* ops, Call* call) override {
+    return channel_->PerformOpsOnCall(ops, call);
+  }
+  void* RegisterMethod(const char* method) override {
+    return channel_->RegisterMethod(method);
+  }
+
+  void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
+                               gpr_timespec deadline, CompletionQueue* cq,
+                               void* tag) override {
+    return channel_->NotifyOnStateChangeImpl(last_observed, deadline, cq, tag);
+  }
+  bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
+                              gpr_timespec deadline) override {
+    return channel_->WaitForStateChangeImpl(last_observed, deadline);
+  }
+
+  CompletionQueue* CallbackCQ() override { return channel_->CallbackCQ(); }
+
+  ChannelInterface* channel_;
+  int interceptor_pos_;
+
+  friend class InterceptorBatchMethodsImpl;
+};
+}  // namespace internal
+}  // namespace grpc
+
+#endif  // GRPCPP_IMPL_CODEGEN_INTERCEPTED_CHANNEL_H

include/grpcpp/impl/codegen/interceptor.h

@@ -19,7 +19,17 @@
 #ifndef GRPCPP_IMPL_CODEGEN_INTERCEPTOR_H
 #define GRPCPP_IMPL_CODEGEN_INTERCEPTOR_H
 
+#include <grpc/impl/codegen/grpc_types.h>
+#include <grpcpp/impl/codegen/byte_buffer.h>
+#include <grpcpp/impl/codegen/config.h>
+#include <grpcpp/impl/codegen/core_codegen_interface.h>
+#include <grpcpp/impl/codegen/metadata_map.h>
+
 namespace grpc {
+
+class ChannelInterface;
+class Status;
+
 namespace experimental {
 class InterceptedMessage {
  public:
@@ -35,6 +45,7 @@ enum class InterceptionHookPoints {
   PRE_SEND_INITIAL_METADATA,
   PRE_SEND_MESSAGE,
   PRE_SEND_STATUS /* server only */,
+  PRE_SEND_CLOSE /* client only */,
   /* The following three are for hijacked clients only and can only be
      registered by the global interceptor */
   PRE_RECV_INITIAL_METADATA,
@@ -50,7 +61,7 @@ enum class InterceptionHookPoints {
 
 class InterceptorBatchMethods {
  public:
-  virtual ~InterceptorBatchMethods();
+  virtual ~InterceptorBatchMethods(){};
   // Queries to check whether the current batch has an interception hook point
   // of type \a type
   virtual bool QueryInterceptionHookPoint(InterceptionHookPoints type) = 0;
@@ -60,7 +71,53 @@ class InterceptorBatchMethods {
   // Calling this indicates that the interceptor has hijacked the RPC (only
   // valid if the batch contains send_initial_metadata on the client side)
   virtual void Hijack() = 0;
+
+  // Returns a modifable ByteBuffer holding serialized form of the message to be
+  // sent
+  virtual ByteBuffer* GetSendMessage() = 0;
+
+  // Returns a modifiable multimap of the initial metadata to be sent
+  virtual std::multimap<grpc::string, grpc::string>*
+  GetSendInitialMetadata() = 0;
+
+  // Returns the status to be sent
+  virtual Status GetSendStatus() = 0;
+
+  // Modifies the status with \a status
+  virtual void ModifySendStatus(const Status& status) = 0;
+
+  // Returns a modifiable multimap of the trailing metadata to be sent
+  virtual std::multimap<grpc::string, grpc::string>*
+  GetSendTrailingMetadata() = 0;
+
+  // Returns a pointer to the modifiable received message. Note that the message
+  // is already deserialized
+  virtual void* GetRecvMessage() = 0;
+
+  // Returns a modifiable multimap of the received initial metadata
+  virtual std::multimap<grpc::string_ref, grpc::string_ref>*
+  GetRecvInitialMetadata() = 0;
+
+  // Returns a modifiable view of the received status
+  virtual Status* GetRecvStatus() = 0;
+
+  // Returns a modifiable multimap of the received trailing metadata
+  virtual std::multimap<grpc::string_ref, grpc::string_ref>*
+  GetRecvTrailingMetadata() = 0;
+
+  // Gets an intercepted channel. When a call is started on this interceptor,
+  // only interceptors after the current interceptor are created from the
+  // factory objects registered with the channel.
+  virtual std::unique_ptr<ChannelInterface> GetInterceptedChannel() = 0;
 };
+
+class Interceptor {
+ public:
+  virtual ~Interceptor() {}
+
+  virtual void Intercept(InterceptorBatchMethods* methods) = 0;
+};
+
 }  // namespace experimental
 }  // namespace grpc
 

include/grpcpp/impl/codegen/interceptor_common.h

@@ -0,0 +1,383 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_INTERCEPTOR_COMMON_H
+#define GRPCPP_IMPL_CODEGEN_INTERCEPTOR_COMMON_H
+
+#include <grpcpp/impl/codegen/client_interceptor.h>
+#include <grpcpp/impl/codegen/server_interceptor.h>
+
+#include <grpc/impl/codegen/grpc_types.h>
+
+namespace grpc {
+namespace internal {
+
+/// Internal methods for setting the state
+class InternalInterceptorBatchMethods
+    : public experimental::InterceptorBatchMethods {
+ public:
+  virtual ~InternalInterceptorBatchMethods() {}
+
+  virtual void AddInterceptionHookPoint(
+      experimental::InterceptionHookPoints type) = 0;
+
+  virtual void SetSendMessage(ByteBuffer* buf) = 0;
+
+  virtual void SetSendInitialMetadata(
+      std::multimap<grpc::string, grpc::string>* metadata) = 0;
+
+  virtual void SetSendStatus(grpc_status_code* code,
+                             grpc::string* error_details,
+                             grpc::string* error_message) = 0;
+
+  virtual void SetSendTrailingMetadata(
+      std::multimap<grpc::string, grpc::string>* metadata) = 0;
+
+  virtual void SetRecvMessage(void* message) = 0;
+
+  virtual void SetRecvInitialMetadata(MetadataMap* map) = 0;
+
+  virtual void SetRecvStatus(Status* status) = 0;
+
+  virtual void SetRecvTrailingMetadata(MetadataMap* map) = 0;
+};
+
+class InterceptorBatchMethodsImpl : public InternalInterceptorBatchMethods {
+ public:
+  InterceptorBatchMethodsImpl() {
+    for (auto i = static_cast<experimental::InterceptionHookPoints>(0);
+         i < experimental::InterceptionHookPoints::NUM_INTERCEPTION_HOOKS;
+         i = static_cast<experimental::InterceptionHookPoints>(
+             static_cast<size_t>(i) + 1)) {
+      hooks_[static_cast<size_t>(i)] = false;
+    }
+  }
+
+  ~InterceptorBatchMethodsImpl() {}
+
+  bool QueryInterceptionHookPoint(
+      experimental::InterceptionHookPoints type) override {
+    return hooks_[static_cast<size_t>(type)];
+  }
+
+  void Proceed() override { /* fill this */
+    if (call_->client_rpc_info() != nullptr) {
+      return ProceedClient();
+    }
+    GPR_CODEGEN_ASSERT(call_->server_rpc_info() != nullptr);
+    ProceedServer();
+  }
+
+  void Hijack() override {
+    // Only the client can hijack when sending down initial metadata
+    GPR_CODEGEN_ASSERT(!reverse_ && ops_ != nullptr &&
+                       call_->client_rpc_info() != nullptr);
+    // It is illegal to call Hijack twice
+    GPR_CODEGEN_ASSERT(!ran_hijacking_interceptor_);
+    auto* rpc_info = call_->client_rpc_info();
+    rpc_info->hijacked_ = true;
+    rpc_info->hijacked_interceptor_ = current_interceptor_index_;
+    ClearHookPoints();
+    ops_->SetHijackingState();
+    ran_hijacking_interceptor_ = true;
+    rpc_info->RunInterceptor(this, current_interceptor_index_);
+  }
+
+  void AddInterceptionHookPoint(
+      experimental::InterceptionHookPoints type) override {
+    hooks_[static_cast<size_t>(type)] = true;
+  }
+
+  ByteBuffer* GetSendMessage() override { return send_message_; }
+
+  std::multimap<grpc::string, grpc::string>* GetSendInitialMetadata() override {
+    return send_initial_metadata_;
+  }
+
+  Status GetSendStatus() override {
+    return Status(static_cast<StatusCode>(*code_), *error_message_,
+                  *error_details_);
+  }
+
+  void ModifySendStatus(const Status& status) override {
+    *code_ = static_cast<grpc_status_code>(status.error_code());
+    *error_details_ = status.error_details();
+    *error_message_ = status.error_message();
+  }
+
+  std::multimap<grpc::string, grpc::string>* GetSendTrailingMetadata()
+      override {
+    return send_trailing_metadata_;
+  }
+
+  void* GetRecvMessage() override { return recv_message_; }
+
+  std::multimap<grpc::string_ref, grpc::string_ref>* GetRecvInitialMetadata()
+      override {
+    return recv_initial_metadata_->map();
+  }
+
+  Status* GetRecvStatus() override { return recv_status_; }
+
+  std::multimap<grpc::string_ref, grpc::string_ref>* GetRecvTrailingMetadata()
+      override {
+    return recv_trailing_metadata_->map();
+  }
+
+  void SetSendMessage(ByteBuffer* buf) override { send_message_ = buf; }
+
+  void SetSendInitialMetadata(
+      std::multimap<grpc::string, grpc::string>* metadata) override {
+    send_initial_metadata_ = metadata;
+  }
+
+  void SetSendStatus(grpc_status_code* code, grpc::string* error_details,
+                     grpc::string* error_message) override {
+    code_ = code;
+    error_details_ = error_details;
+    error_message_ = error_message;
+  }
+
+  void SetSendTrailingMetadata(
+      std::multimap<grpc::string, grpc::string>* metadata) override {
+    send_trailing_metadata_ = metadata;
+  }
+
+  void SetRecvMessage(void* message) override { recv_message_ = message; }
+
+  void SetRecvInitialMetadata(MetadataMap* map) override {
+    recv_initial_metadata_ = map;
+  }
+
+  void SetRecvStatus(Status* status) override { recv_status_ = status; }
+
+  void SetRecvTrailingMetadata(MetadataMap* map) override {
+    recv_trailing_metadata_ = map;
+  }
+
+  std::unique_ptr<ChannelInterface> GetInterceptedChannel() override {
+    auto* info = call_->client_rpc_info();
+    if (info == nullptr) {
+      return std::unique_ptr<ChannelInterface>(nullptr);
+    }
+    // The intercepted channel starts from the interceptor just after the
+    // current interceptor
+    return std::unique_ptr<ChannelInterface>(new InterceptedChannel(
+        info->channel(), current_interceptor_index_ + 1));
+  }
+
+  // Clears all state
+  void ClearState() {
+    reverse_ = false;
+    ran_hijacking_interceptor_ = false;
+    ClearHookPoints();
+  }
+
+  // Prepares for Post_recv operations
+  void SetReverse() {
+    reverse_ = true;
+    ran_hijacking_interceptor_ = false;
+    ClearHookPoints();
+  }
+
+  // This needs to be set before interceptors are run
+  void SetCall(Call* call) { call_ = call; }
+
+  // This needs to be set before interceptors are run using RunInterceptors().
+  // Alternatively, RunInterceptors(std::function<void(void)> f) can be used.
+  void SetCallOpSetInterface(CallOpSetInterface* ops) { ops_ = ops; }
+
+  // Returns true if no interceptors are run. This should be used only by
+  // subclasses of CallOpSetInterface. SetCall and SetCallOpSetInterface should
+  // have been called before this. After all the interceptors are done running,
+  // either ContinueFillOpsAfterInterception or
+  // ContinueFinalizeOpsAfterInterception will be called. Note that neither of
+  // them is invoked if there were no interceptors registered.
+  bool RunInterceptors() {
+    GPR_CODEGEN_ASSERT(ops_);
+    auto* client_rpc_info = call_->client_rpc_info();
+    if (client_rpc_info != nullptr) {
+      if (client_rpc_info->interceptors_.size() == 0) {
+        return true;
+      } else {
+        RunClientInterceptors();
+        return false;
+      }
+    }
+
+    auto* server_rpc_info = call_->server_rpc_info();
+    if (server_rpc_info == nullptr ||
+        server_rpc_info->interceptors_.size() == 0) {
+      return true;
+    }
+    RunServerInterceptors();
+    return false;
+  }
+
+  // Returns true if no interceptors are run. Returns false otherwise if there
+  // are interceptors registered. After the interceptors are done running \a f
+  // will be invoked. This is to be used only by BaseAsyncRequest and
+  // SyncRequest.
+  bool RunInterceptors(std::function<void(void)> f) {
+    // This is used only by the server for initial call request
+    GPR_CODEGEN_ASSERT(reverse_ == true);
+    GPR_CODEGEN_ASSERT(call_->client_rpc_info() == nullptr);
+    auto* server_rpc_info = call_->server_rpc_info();
+    if (server_rpc_info == nullptr ||
+        server_rpc_info->interceptors_.size() == 0) {
+      return true;
+    }
+    callback_ = std::move(f);
+    RunServerInterceptors();
+    return false;
+  }
+
+ private:
+  void RunClientInterceptors() {
+    auto* rpc_info = call_->client_rpc_info();
+    if (!reverse_) {
+      current_interceptor_index_ = 0;
+    } else {
+      if (rpc_info->hijacked_) {
+        current_interceptor_index_ = rpc_info->hijacked_interceptor_;
+      } else {
+        current_interceptor_index_ = rpc_info->interceptors_.size() - 1;
+      }
+    }
+    rpc_info->RunInterceptor(this, current_interceptor_index_);
+  }
+
+  void RunServerInterceptors() {
+    auto* rpc_info = call_->server_rpc_info();
+    if (!reverse_) {
+      current_interceptor_index_ = 0;
+    } else {
+      current_interceptor_index_ = rpc_info->interceptors_.size() - 1;
+    }
+    rpc_info->RunInterceptor(this, current_interceptor_index_);
+  }
+
+  void ProceedClient() {
+    auto* rpc_info = call_->client_rpc_info();
+    if (rpc_info->hijacked_ && !reverse_ &&
+        current_interceptor_index_ == rpc_info->hijacked_interceptor_ &&
+        !ran_hijacking_interceptor_) {
+      // We now need to provide hijacked recv ops to this interceptor
+      ClearHookPoints();
+      ops_->SetHijackingState();
+      ran_hijacking_interceptor_ = true;
+      rpc_info->RunInterceptor(this, current_interceptor_index_);
+      return;
+    }
+    if (!reverse_) {
+      current_interceptor_index_++;
+      // We are going down the stack of interceptors
+      if (current_interceptor_index_ < rpc_info->interceptors_.size()) {
+        if (rpc_info->hijacked_ &&
+            current_interceptor_index_ > rpc_info->hijacked_interceptor_) {
+          // This is a hijacked RPC and we are done with hijacking
+          ops_->ContinueFillOpsAfterInterception();
+        } else {
+          rpc_info->RunInterceptor(this, current_interceptor_index_);
+        }
+      } else {
+        // we are done running all the interceptors without any hijacking
+        ops_->ContinueFillOpsAfterInterception();
+      }
+    } else {
+      // We are going up the stack of interceptors
+      if (current_interceptor_index_ > 0) {
+        // Continue running interceptors
+        current_interceptor_index_--;
+        rpc_info->RunInterceptor(this, current_interceptor_index_);
+      } else {
+        // we are done running all the interceptors without any hijacking
+        ops_->ContinueFinalizeResultAfterInterception();
+      }
+    }
+  }
+
+  void ProceedServer() {
+    auto* rpc_info = call_->server_rpc_info();
+    if (!reverse_) {
+      current_interceptor_index_++;
+      if (current_interceptor_index_ < rpc_info->interceptors_.size()) {
+        return rpc_info->RunInterceptor(this, current_interceptor_index_);
+      } else if (ops_) {
+        return ops_->ContinueFillOpsAfterInterception();
+      }
+    } else {
+      // We are going up the stack of interceptors
+      if (current_interceptor_index_ > 0) {
+        // Continue running interceptors
+        current_interceptor_index_--;
+        return rpc_info->RunInterceptor(this, current_interceptor_index_);
+      } else if (ops_) {
+        return ops_->ContinueFinalizeResultAfterInterception();
+      }
+    }
+    GPR_CODEGEN_ASSERT(callback_);
+    callback_();
+  }
+
+  void ClearHookPoints() {
+    for (auto i = static_cast<experimental::InterceptionHookPoints>(0);
+         i < experimental::InterceptionHookPoints::NUM_INTERCEPTION_HOOKS;
+         i = static_cast<experimental::InterceptionHookPoints>(
+             static_cast<size_t>(i) + 1)) {
+      hooks_[static_cast<size_t>(i)] = false;
+    }
+  }
+
+  std::array<bool,
+             static_cast<size_t>(
+                 experimental::InterceptionHookPoints::NUM_INTERCEPTION_HOOKS)>
+      hooks_;
+
+  size_t current_interceptor_index_ = 0;  // Current iterator
+  bool reverse_ = false;
+  bool ran_hijacking_interceptor_ = false;
+  Call* call_ = nullptr;  // The Call object is present along with CallOpSet
+                          // object/callback
+  CallOpSetInterface* ops_ = nullptr;
+  std::function<void(void)> callback_;
+
+  ByteBuffer* send_message_ = nullptr;
+
+  std::multimap<grpc::string, grpc::string>* send_initial_metadata_;
+
+  grpc_status_code* code_ = nullptr;
+  grpc::string* error_details_ = nullptr;
+  grpc::string* error_message_ = nullptr;
+  Status send_status_;
+
+  std::multimap<grpc::string, grpc::string>* send_trailing_metadata_ = nullptr;
+
+  void* recv_message_ = nullptr;
+
+  MetadataMap* recv_initial_metadata_ = nullptr;
+
+  Status* recv_status_ = nullptr;
+
+  MetadataMap* recv_trailing_metadata_ = nullptr;
+};
+
+}  // namespace internal
+}  // namespace grpc
+
+#endif  // GRPCPP_IMPL_CODEGEN_INTERCEPTOR_COMMON_H

include/grpcpp/impl/codegen/metadata_map.h

@@ -19,6 +19,8 @@
 #ifndef GRPCPP_IMPL_CODEGEN_METADATA_MAP_H
 #define GRPCPP_IMPL_CODEGEN_METADATA_MAP_H
 
+#include <map>
+
 #include <grpc/impl/codegen/log.h>
 #include <grpcpp/impl/codegen/slice.h>
 

include/grpcpp/impl/codegen/method_handler_impl.h

@@ -59,21 +59,21 @@ class RpcMethodHandler : public MethodHandler {
       : func_(func), service_(service) {}
 
   void RunHandler(const HandlerParameter& param) final {
-    RequestType req;
-    Status status = SerializationTraits<RequestType>::Deserialize(
-        param.request.bbuf_ptr(), &req);
     ResponseType rsp;
+    Status status = param.status;
     if (status.ok()) {
-      status = CatchingFunctionHandler([this, &param, &req, &rsp] {
-        return func_(service_, param.server_context, &req, &rsp);
+      status = CatchingFunctionHandler([this, &param, &rsp] {
+        return func_(service_, param.server_context,
+                     static_cast<RequestType*>(param.request), &rsp);
       });
+      static_cast<RequestType*>(param.request)->~RequestType();
     }
 
     GPR_CODEGEN_ASSERT(!param.server_context->sent_initial_metadata_);
     CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
               CallOpServerSendStatus>
         ops;
-    ops.SendInitialMetadata(param.server_context->initial_metadata_,
+    ops.SendInitialMetadata(&param.server_context->initial_metadata_,
                             param.server_context->initial_metadata_flags());
     if (param.server_context->compression_level_set()) {
       ops.set_compression_level(param.server_context->compression_level());
@@ -81,11 +81,26 @@ class RpcMethodHandler : public MethodHandler {
     if (status.ok()) {
       status = ops.SendMessage(rsp);
     }
-    ops.ServerSendStatus(param.server_context->trailing_metadata_, status);
+    ops.ServerSendStatus(&param.server_context->trailing_metadata_, status);
     param.call->PerformOps(&ops);
     param.call->cq()->Pluck(&ops);
   }
 
+  void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                    Status* status) final {
+    ByteBuffer buf;
+    buf.set_buffer(req);
+    auto* request = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        call, sizeof(RequestType))) RequestType();
+    *status = SerializationTraits<RequestType>::Deserialize(&buf, request);
+    buf.Release();
+    if (status->ok()) {
+      return request;
+    }
+    request->~RequestType();
+    return nullptr;
+  }
+
  private:
   /// Application provided rpc handler function.
   std::function<Status(ServiceType*, ServerContext*, const RequestType*,
@@ -117,7 +132,7 @@ class ClientStreamingHandler : public MethodHandler {
               CallOpServerSendStatus>
         ops;
     if (!param.server_context->sent_initial_metadata_) {
-      ops.SendInitialMetadata(param.server_context->initial_metadata_,
+      ops.SendInitialMetadata(&param.server_context->initial_metadata_,
                               param.server_context->initial_metadata_flags());
       if (param.server_context->compression_level_set()) {
         ops.set_compression_level(param.server_context->compression_level());
@@ -126,7 +141,7 @@ class ClientStreamingHandler : public MethodHandler {
     if (status.ok()) {
       status = ops.SendMessage(rsp);
     }
-    ops.ServerSendStatus(param.server_context->trailing_metadata_, status);
+    ops.ServerSendStatus(&param.server_context->trailing_metadata_, status);
     param.call->PerformOps(&ops);
     param.call->cq()->Pluck(&ops);
   }
@@ -150,26 +165,25 @@ class ServerStreamingHandler : public MethodHandler {
       : func_(func), service_(service) {}
 
   void RunHandler(const HandlerParameter& param) final {
-    RequestType req;
-    Status status = SerializationTraits<RequestType>::Deserialize(
-        param.request.bbuf_ptr(), &req);
-
+    Status status = param.status;
     if (status.ok()) {
       ServerWriter<ResponseType> writer(param.call, param.server_context);
-      status = CatchingFunctionHandler([this, &param, &req, &writer] {
-        return func_(service_, param.server_context, &req, &writer);
+      status = CatchingFunctionHandler([this, &param, &writer] {
+        return func_(service_, param.server_context,
+                     static_cast<RequestType*>(param.request), &writer);
       });
+      static_cast<RequestType*>(param.request)->~RequestType();
     }
 
     CallOpSet<CallOpSendInitialMetadata, CallOpServerSendStatus> ops;
     if (!param.server_context->sent_initial_metadata_) {
-      ops.SendInitialMetadata(param.server_context->initial_metadata_,
+      ops.SendInitialMetadata(&param.server_context->initial_metadata_,
                               param.server_context->initial_metadata_flags());
       if (param.server_context->compression_level_set()) {
         ops.set_compression_level(param.server_context->compression_level());
       }
     }
-    ops.ServerSendStatus(param.server_context->trailing_metadata_, status);
+    ops.ServerSendStatus(&param.server_context->trailing_metadata_, status);
     param.call->PerformOps(&ops);
     if (param.server_context->has_pending_ops_) {
       param.call->cq()->Pluck(&param.server_context->pending_ops_);
@@ -177,6 +191,21 @@ class ServerStreamingHandler : public MethodHandler {
     param.call->cq()->Pluck(&ops);
   }
 
+  void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                    Status* status) final {
+    ByteBuffer buf;
+    buf.set_buffer(req);
+    auto* request = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        call, sizeof(RequestType))) RequestType();
+    *status = SerializationTraits<RequestType>::Deserialize(&buf, request);
+    buf.Release();
+    if (status->ok()) {
+      return request;
+    }
+    request->~RequestType();
+    return nullptr;
+  }
+
  private:
   std::function<Status(ServiceType*, ServerContext*, const RequestType*,
                        ServerWriter<ResponseType>*)>
@@ -206,7 +235,7 @@ class TemplatedBidiStreamingHandler : public MethodHandler {
 
     CallOpSet<CallOpSendInitialMetadata, CallOpServerSendStatus> ops;
     if (!param.server_context->sent_initial_metadata_) {
-      ops.SendInitialMetadata(param.server_context->initial_metadata_,
+      ops.SendInitialMetadata(&param.server_context->initial_metadata_,
                               param.server_context->initial_metadata_flags());
       if (param.server_context->compression_level_set()) {
         ops.set_compression_level(param.server_context->compression_level());
@@ -218,7 +247,7 @@ class TemplatedBidiStreamingHandler : public MethodHandler {
                         "Service did not provide response message");
       }
     }
-    ops.ServerSendStatus(param.server_context->trailing_metadata_, status);
+    ops.ServerSendStatus(&param.server_context->trailing_metadata_, status);
     param.call->PerformOps(&ops);
     if (param.server_context->has_pending_ops_) {
       param.call->cq()->Pluck(&param.server_context->pending_ops_);
@@ -281,14 +310,14 @@ class ErrorMethodHandler : public MethodHandler {
   static void FillOps(ServerContext* context, T* ops) {
     Status status(code, "");
     if (!context->sent_initial_metadata_) {
-      ops->SendInitialMetadata(context->initial_metadata_,
+      ops->SendInitialMetadata(&context->initial_metadata_,
                                context->initial_metadata_flags());
       if (context->compression_level_set()) {
         ops->set_compression_level(context->compression_level());
       }
       context->sent_initial_metadata_ = true;
     }
-    ops->ServerSendStatus(context->trailing_metadata_, status);
+    ops->ServerSendStatus(&context->trailing_metadata_, status);
   }
 
   void RunHandler(const HandlerParameter& param) final {
@@ -296,11 +325,15 @@ class ErrorMethodHandler : public MethodHandler {
     FillOps(param.server_context, &ops);
     param.call->PerformOps(&ops);
     param.call->cq()->Pluck(&ops);
-    // We also have to destroy any request payload in the handler parameter
-    ByteBuffer* payload = param.request.bbuf_ptr();
-    if (payload != nullptr) {
-      payload->Clear();
+  }
+
+  void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                    Status* status) final {
+    // We have to destroy any request payload
+    if (req != nullptr) {
+      g_core_codegen_interface->grpc_byte_buffer_destroy(req);
     }
+    return nullptr;
   }
 };
 

include/grpcpp/impl/codegen/rpc_service_method.h

@@ -40,17 +40,41 @@ class MethodHandler {
  public:
   virtual ~MethodHandler() {}
   struct HandlerParameter {
-    HandlerParameter(Call* c, ServerContext* context, grpc_byte_buffer* req)
-        : call(c), server_context(context) {
-      request.set_buffer(req);
-    }
-    ~HandlerParameter() { request.Release(); }
+    /// Constructor for HandlerParameter
+    ///
+    /// \param c : the gRPC Call structure for this server call
+    /// \param context : the ServerContext structure for this server call
+    /// \param req : the request payload, if appropriate for this RPC
+    /// \param req_status : the request status after any interceptors have run
+    /// \param rpc_requester : used only by the callback API. It is a function
+    ///        called by the RPC Controller to request another RPC (and also
+    ///        to set up the state required to make that request possible)
+    HandlerParameter(Call* c, ServerContext* context, void* req,
+                     Status req_status, std::function<void()> requester)
+        : call(c),
+          server_context(context),
+          request(req),
+          status(req_status),
+          call_requester(std::move(requester)) {}
+    ~HandlerParameter() {}
     Call* call;
     ServerContext* server_context;
-    // Handler required to destroy these contents
-    ByteBuffer request;
+    void* request;
+    Status status;
+    std::function<void()> call_requester;
   };
   virtual void RunHandler(const HandlerParameter& param) = 0;
+
+  /* Returns a pointer to the deserialized request. \a status reflects the
+     result of deserialization. This pointer and the status should be filled in
+     a HandlerParameter and passed to RunHandler. It is illegal to access the
+     pointer after calling RunHandler. Ownership of the deserialized request is
+     retained by the handler. Returns nullptr if deserialization failed. */
+  virtual void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                            Status* status) {
+    GPR_CODEGEN_ASSERT(req == nullptr);
+    return nullptr;
+  }
 };
 
 /// Server side rpc method class
@@ -61,25 +85,29 @@ class RpcServiceMethod : public RpcMethod {
                    MethodHandler* handler)
       : RpcMethod(name, type),
         server_tag_(nullptr),
-        async_type_(AsyncType::UNSET),
+        api_type_(ApiType::SYNC),
         handler_(handler) {}
 
-  enum class AsyncType {
-    UNSET,
+  enum class ApiType {
+    SYNC,
     ASYNC,
     RAW,
+    CALL_BACK,  // not CALLBACK because that is reserved in Windows
+    RAW_CALL_BACK,
   };
 
   void set_server_tag(void* tag) { server_tag_ = tag; }
   void* server_tag() const { return server_tag_; }
   /// if MethodHandler is nullptr, then this is an async method
   MethodHandler* handler() const { return handler_.get(); }
+  ApiType api_type() const { return api_type_; }
   void SetHandler(MethodHandler* handler) { handler_.reset(handler); }
-  void SetServerAsyncType(RpcServiceMethod::AsyncType type) {
-    if (async_type_ == AsyncType::UNSET) {
+  void SetServerApiType(RpcServiceMethod::ApiType type) {
+    if ((api_type_ == ApiType::SYNC) &&
+        (type == ApiType::ASYNC || type == ApiType::RAW)) {
       // this marks this method as async
       handler_.reset();
-    } else {
+    } else if (api_type_ != ApiType::SYNC) {
       // this is not an error condition, as it allows users to declare a server
       // like WithRawMethod_foo<AsyncService>. However since it
       // overwrites behavior, it should be logged.
@@ -88,24 +116,28 @@ class RpcServiceMethod : public RpcMethod {
           "You are marking method %s as '%s', even though it was "
           "previously marked '%s'. This behavior will overwrite the original "
           "behavior. If you expected this then ignore this message.",
-          name(), TypeToString(async_type_), TypeToString(type));
+          name(), TypeToString(api_type_), TypeToString(type));
     }
-    async_type_ = type;
+    api_type_ = type;
   }
 
  private:
   void* server_tag_;
-  AsyncType async_type_;
+  ApiType api_type_;
   std::unique_ptr<MethodHandler> handler_;
 
-  const char* TypeToString(RpcServiceMethod::AsyncType type) {
+  const char* TypeToString(RpcServiceMethod::ApiType type) {
     switch (type) {
-      case AsyncType::UNSET:
-        return "unset";
-      case AsyncType::ASYNC:
+      case ApiType::SYNC:
+        return "sync";
+      case ApiType::ASYNC:
         return "async";
-      case AsyncType::RAW:
+      case ApiType::RAW:
         return "raw";
+      case ApiType::CALL_BACK:
+        return "callback";
+      case ApiType::RAW_CALL_BACK:
+        return "raw_callback";
       default:
         GPR_UNREACHABLE_CODE(return "unknown");
     }

include/grpcpp/impl/codegen/server_callback.h

@@ -0,0 +1,200 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H
+#define GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H
+
+#include <functional>
+
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/callback_common.h>
+#include <grpcpp/impl/codegen/config.h>
+#include <grpcpp/impl/codegen/core_codegen_interface.h>
+#include <grpcpp/impl/codegen/server_context.h>
+#include <grpcpp/impl/codegen/server_interface.h>
+#include <grpcpp/impl/codegen/status.h>
+
+namespace grpc {
+
+// forward declarations
+namespace internal {
+template <class ServiceType, class RequestType, class ResponseType>
+class CallbackUnaryHandler;
+}  // namespace internal
+
+namespace experimental {
+
+// For unary RPCs, the exposed controller class is only an interface
+// and the actual implementation is an internal class.
+class ServerCallbackRpcController {
+ public:
+  virtual ~ServerCallbackRpcController() {}
+
+  // The method handler must call this function when it is done so that
+  // the library knows to free its resources
+  virtual void Finish(Status s) = 0;
+
+  // Allow the method handler to push out the initial metadata before
+  // the response and status are ready
+  virtual void SendInitialMetadata(std::function<void(bool)>) = 0;
+};
+
+}  // namespace experimental
+
+namespace internal {
+
+template <class ServiceType, class RequestType, class ResponseType>
+class CallbackUnaryHandler : public MethodHandler {
+ public:
+  CallbackUnaryHandler(
+      std::function<void(ServerContext*, const RequestType*, ResponseType*,
+                         experimental::ServerCallbackRpcController*)>
+          func,
+      ServiceType* service)
+      : func_(func) {}
+  void RunHandler(const HandlerParameter& param) final {
+    // Arena allocate a controller structure (that includes request/response)
+    g_core_codegen_interface->grpc_call_ref(param.call->call());
+    auto* controller = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        param.call->call(), sizeof(ServerCallbackRpcControllerImpl)))
+        ServerCallbackRpcControllerImpl(
+            param.server_context, param.call,
+            static_cast<RequestType*>(param.request),
+            std::move(param.call_requester));
+    Status status = param.status;
+
+    if (status.ok()) {
+      // Call the actual function handler and expect the user to call finish
+      CatchingCallback(std::move(func_), param.server_context,
+                       controller->request(), controller->response(),
+                       controller);
+    } else {
+      // if deserialization failed, we need to fail the call
+      controller->Finish(status);
+    }
+  }
+
+  void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                    Status* status) final {
+    ByteBuffer buf;
+    buf.set_buffer(req);
+    auto* request = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        call, sizeof(RequestType))) RequestType();
+    *status = SerializationTraits<RequestType>::Deserialize(&buf, request);
+    buf.Release();
+    if (status->ok()) {
+      return request;
+    }
+    request->~RequestType();
+    return nullptr;
+  }
+
+ private:
+  std::function<void(ServerContext*, const RequestType*, ResponseType*,
+                     experimental::ServerCallbackRpcController*)>
+      func_;
+
+  // The implementation class of ServerCallbackRpcController is a private member
+  // of CallbackUnaryHandler since it is never exposed anywhere, and this allows
+  // it to take advantage of CallbackUnaryHandler's friendships.
+  class ServerCallbackRpcControllerImpl
+      : public experimental::ServerCallbackRpcController {
+   public:
+    void Finish(Status s) override {
+      finish_tag_ = CallbackWithSuccessTag(
+          call_.call(),
+          [this](bool) {
+            grpc_call* call = call_.call();
+            auto call_requester = std::move(call_requester_);
+            this->~ServerCallbackRpcControllerImpl();  // explicitly call
+                                                       // destructor
+            g_core_codegen_interface->grpc_call_unref(call);
+            call_requester();
+          },
+          &finish_buf_);
+      if (!ctx_->sent_initial_metadata_) {
+        finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_buf_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // The response is dropped if the status is not OK.
+      if (s.ok()) {
+        finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_,
+                                     finish_buf_.SendMessage(resp_));
+      } else {
+        finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      }
+      finish_buf_.set_core_cq_tag(&finish_tag_);
+      call_.PerformOps(&finish_buf_);
+    }
+
+    void SendInitialMetadata(std::function<void(bool)> f) override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+      meta_tag_ =
+          CallbackWithSuccessTag(call_.call(), std::move(f), &meta_buf_);
+      meta_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_buf_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_buf_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_buf_);
+    }
+
+   private:
+    template <class SrvType, class ReqType, class RespType>
+    friend class CallbackUnaryHandler;
+
+    ServerCallbackRpcControllerImpl(ServerContext* ctx, Call* call,
+                                    RequestType* req,
+                                    std::function<void()> call_requester)
+        : ctx_(ctx),
+          call_(*call),
+          req_(req),
+          call_requester_(std::move(call_requester)) {}
+
+    ~ServerCallbackRpcControllerImpl() { req_->~RequestType(); }
+
+    RequestType* request() { return req_; }
+    ResponseType* response() { return &resp_; }
+
+    CallOpSet<CallOpSendInitialMetadata> meta_buf_;
+    CallbackWithSuccessTag meta_tag_;
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
+              CallOpServerSendStatus>
+        finish_buf_;
+    CallbackWithSuccessTag finish_tag_;
+
+    ServerContext* ctx_;
+    Call call_;
+    RequestType* req_;
+    ResponseType resp_;
+    std::function<void()> call_requester_;
+  };
+};
+
+}  // namespace internal
+
+}  // namespace grpc
+
+#endif  // GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H

include/grpcpp/impl/codegen/server_context.h

@@ -26,11 +26,14 @@
 #include <grpc/impl/codegen/compression_types.h>
 
 #include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/call_op_set.h>
+#include <grpcpp/impl/codegen/callback_common.h>
 #include <grpcpp/impl/codegen/completion_queue_tag.h>
 #include <grpcpp/impl/codegen/config.h>
 #include <grpcpp/impl/codegen/create_auth_context.h>
 #include <grpcpp/impl/codegen/metadata_map.h>
 #include <grpcpp/impl/codegen/security/auth_context.h>
+#include <grpcpp/impl/codegen/server_interceptor.h>
 #include <grpcpp/impl/codegen/string_ref.h>
 #include <grpcpp/impl/codegen/time.h>
 
@@ -63,6 +66,8 @@ template <class ServiceType, class RequestType, class ResponseType>
 class ServerStreamingHandler;
 template <class ServiceType, class RequestType, class ResponseType>
 class BidiStreamingHandler;
+template <class ServiceType, class RequestType, class ResponseType>
+class CallbackUnaryHandler;
 template <class Streamer, bool WriteNeeded>
 class TemplatedBidiStreamingHandler;
 template <StatusCode code>
@@ -107,7 +112,7 @@ class ServerContext {
   /// Return a \a gpr_timespec representation of the server call's deadline.
   gpr_timespec raw_deadline() const { return deadline_; }
 
-  /// Add the (\a meta_key, \a meta_value) pair to the initial metadata
+  /// Add the (\a key, \a value) pair to the initial metadata
   /// associated with a server call. These are made available at the client side
   /// by the \a grpc::ClientContext::GetServerInitialMetadata() method.
   ///
@@ -115,13 +120,13 @@ class ServerContext {
   /// to the client (which can happen explicitly, or implicitly when sending a
   /// a response message or status to the client).
   ///
-  /// \param meta_key The metadata key. If \a meta_value is binary data, it must
+  /// \param key The metadata key. If \a value is binary data, it must
   /// end in "-bin".
-  /// \param meta_value The metadata value. If its value is binary, the key name
+  /// \param value The metadata value. If its value is binary, the key name
   /// must end in "-bin".
   void AddInitialMetadata(const grpc::string& key, const grpc::string& value);
 
-  /// Add the (\a meta_key, \a meta_value) pair to the initial metadata
+  /// Add the (\a key, \a value) pair to the initial metadata
   /// associated with a server call. These are made available at the client
   /// side by the \a grpc::ClientContext::GetServerTrailingMetadata() method.
   ///
@@ -129,13 +134,13 @@ class ServerContext {
   /// metadata to the client (which happens when the call is finished and a
   /// status is sent to the client).
   ///
-  /// \param meta_key The metadata key. If \a meta_value is binary data,
+  /// \param key The metadata key. If \a value is binary data,
   /// it must end in "-bin".
-  /// \param meta_value The metadata value. If its value is binary, the key name
+  /// \param value The metadata value. If its value is binary, the key name
   /// must end in "-bin".
   void AddTrailingMetadata(const grpc::string& key, const grpc::string& value);
 
-  /// IsCancelled is always safe to call when using sync API.
+  /// IsCancelled is always safe to call when using sync or callback API.
   /// When using async API, it is only safe to call IsCancelled after
   /// the AsyncNotifyWhenDone tag has been delivered.
   bool IsCancelled() const;
@@ -177,9 +182,9 @@ class ServerContext {
     return compression_level_;
   }
 
-  /// Set \a algorithm to be the compression algorithm used for the server call.
+  /// Set \a level to be the compression level used for the server call.
   ///
-  /// \param algorithm The compression algorithm used for the server call.
+  /// \param level The compression level used for the server call.
   void set_compression_level(grpc_compression_level level) {
     compression_level_set_ = true;
     compression_level_ = level;
@@ -265,6 +270,8 @@ class ServerContext {
   friend class ::grpc::internal::ServerStreamingHandler;
   template <class Streamer, bool WriteNeeded>
   friend class ::grpc::internal::TemplatedBidiStreamingHandler;
+  template <class ServiceType, class RequestType, class ResponseType>
+  friend class ::grpc::internal::CallbackUnaryHandler;
   template <StatusCode code>
   friend class internal::ErrorMethodHandler;
   friend class ::grpc::ClientContext;
@@ -275,7 +282,7 @@ class ServerContext {
 
   class CompletionOp;
 
-  void BeginCompletionOp(internal::Call* call);
+  void BeginCompletionOp(internal::Call* call, bool callback);
   /// Return the tag queued by BeginCompletionOp()
   internal::CompletionQueueTag* GetCompletionOpTag();
 
@@ -283,11 +290,30 @@ class ServerContext {
 
   void set_call(grpc_call* call) { call_ = call; }
 
+  void BindDeadlineAndMetadata(gpr_timespec deadline, grpc_metadata_array* arr);
+
+  void Clear();
+
+  void Setup(gpr_timespec deadline);
+
   uint32_t initial_metadata_flags() const { return 0; }
 
+  experimental::ServerRpcInfo* set_server_rpc_info(
+      const char* method,
+      const std::vector<
+          std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>&
+          creators) {
+    if (creators.size() != 0) {
+      rpc_info_ = new experimental::ServerRpcInfo(this, method);
+      rpc_info_->RegisterInterceptors(creators);
+    }
+    return rpc_info_;
+  }
+
   CompletionOp* completion_op_;
   bool has_notify_when_done_tag_;
   void* async_notify_when_done_tag_;
+  internal::CallbackWithSuccessTag completion_tag_;
 
   gpr_timespec deadline_;
   grpc_call* call_;
@@ -306,6 +332,8 @@ class ServerContext {
                       internal::CallOpSendMessage>
       pending_ops_;
   bool has_pending_ops_;
+
+  experimental::ServerRpcInfo* rpc_info_;
 };
 
 }  // namespace grpc

include/grpcpp/impl/codegen/server_interceptor.h

@@ -0,0 +1,99 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_SERVER_INTERCEPTOR_H
+#define GRPCPP_IMPL_CODEGEN_SERVER_INTERCEPTOR_H
+
+#include <atomic>
+#include <vector>
+
+#include <grpcpp/impl/codegen/interceptor.h>
+#include <grpcpp/impl/codegen/string_ref.h>
+
+namespace grpc {
+
+class ServerContext;
+
+namespace internal {
+class InterceptorBatchMethodsImpl;
+}
+
+namespace experimental {
+class ServerRpcInfo;
+
+class ServerInterceptorFactoryInterface {
+ public:
+  virtual ~ServerInterceptorFactoryInterface() {}
+  virtual Interceptor* CreateServerInterceptor(ServerRpcInfo* info) = 0;
+};
+
+class ServerRpcInfo {
+ public:
+  ~ServerRpcInfo(){};
+
+  ServerRpcInfo(const ServerRpcInfo&) = delete;
+  ServerRpcInfo(ServerRpcInfo&&) = default;
+  ServerRpcInfo& operator=(ServerRpcInfo&&) = default;
+
+  // Getter methods
+  const char* method() { return method_; }
+  grpc::ServerContext* server_context() { return ctx_; }
+
+ private:
+  ServerRpcInfo(grpc::ServerContext* ctx, const char* method)
+      : ctx_(ctx), method_(method) {
+    ref_.store(1);
+  }
+
+  // Runs interceptor at pos \a pos.
+  void RunInterceptor(
+      experimental::InterceptorBatchMethods* interceptor_methods, size_t pos) {
+    GPR_CODEGEN_ASSERT(pos < interceptors_.size());
+    interceptors_[pos]->Intercept(interceptor_methods);
+  }
+
+  void RegisterInterceptors(
+      const std::vector<
+          std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>&
+          creators) {
+    for (const auto& creator : creators) {
+      interceptors_.push_back(std::unique_ptr<experimental::Interceptor>(
+          creator->CreateServerInterceptor(this)));
+    }
+  }
+
+  void Ref() { ref_++; }
+  void Unref() {
+    if (--ref_ == 0) {
+      delete this;
+    }
+  }
+
+  grpc::ServerContext* ctx_ = nullptr;
+  const char* method_ = nullptr;
+  std::atomic_int ref_;
+  std::vector<std::unique_ptr<experimental::Interceptor>> interceptors_;
+
+  friend class internal::InterceptorBatchMethodsImpl;
+  friend class grpc::ServerContext;
+};
+
+}  // namespace experimental
+}  // namespace grpc
+
+#endif  // GRPCPP_IMPL_CODEGEN_SERVER_INTERCEPTOR_H

include/grpcpp/impl/codegen/server_interface.h

@@ -21,10 +21,12 @@
 
 #include <grpc/impl/codegen/grpc_types.h>
 #include <grpcpp/impl/codegen/byte_buffer.h>
+#include <grpcpp/impl/codegen/call.h>
 #include <grpcpp/impl/codegen/call_hook.h>
 #include <grpcpp/impl/codegen/completion_queue_tag.h>
 #include <grpcpp/impl/codegen/core_codegen_interface.h>
 #include <grpcpp/impl/codegen/rpc_service_method.h>
+#include <grpcpp/impl/codegen/server_context.h>
 
 namespace grpc {
 
@@ -148,44 +150,67 @@ class ServerInterface : public internal::CallHook {
    public:
     BaseAsyncRequest(ServerInterface* server, ServerContext* context,
                      internal::ServerAsyncStreamingInterface* stream,
-                     CompletionQueue* call_cq, void* tag,
+                     CompletionQueue* call_cq,
+                     ServerCompletionQueue* notification_cq, void* tag,
                      bool delete_on_finalize);
     virtual ~BaseAsyncRequest();
 
     bool FinalizeResult(void** tag, bool* status) override;
 
+   private:
+    void ContinueFinalizeResultAfterInterception();
+
    protected:
     ServerInterface* const server_;
     ServerContext* const context_;
     internal::ServerAsyncStreamingInterface* const stream_;
     CompletionQueue* const call_cq_;
+    ServerCompletionQueue* const notification_cq_;
     void* const tag_;
     const bool delete_on_finalize_;
     grpc_call* call_;
+    internal::Call call_wrapper_;
+    internal::InterceptorBatchMethodsImpl interceptor_methods_;
+    bool done_intercepting_;
   };
 
   class RegisteredAsyncRequest : public BaseAsyncRequest {
    public:
     RegisteredAsyncRequest(ServerInterface* server, ServerContext* context,
                            internal::ServerAsyncStreamingInterface* stream,
-                           CompletionQueue* call_cq, void* tag);
-
-    // uses BaseAsyncRequest::FinalizeResult
+                           CompletionQueue* call_cq,
+                           ServerCompletionQueue* notification_cq, void* tag,
+                           const char* name);
+
+    virtual bool FinalizeResult(void** tag, bool* status) override {
+      /* If we are done intercepting, then there is nothing more for us to do */
+      if (done_intercepting_) {
+        return BaseAsyncRequest::FinalizeResult(tag, status);
+      }
+      call_wrapper_ = internal::Call(
+          call_, server_, call_cq_, server_->max_receive_message_size(),
+          context_->set_server_rpc_info(name_,
+                                        *server_->interceptor_creators()));
+      return BaseAsyncRequest::FinalizeResult(tag, status);
+    }
 
    protected:
     void IssueRequest(void* registered_method, grpc_byte_buffer** payload,
                       ServerCompletionQueue* notification_cq);
+    const char* name_;
   };
 
   class NoPayloadAsyncRequest final : public RegisteredAsyncRequest {
    public:
-    NoPayloadAsyncRequest(void* registered_method, ServerInterface* server,
-                          ServerContext* context,
+    NoPayloadAsyncRequest(internal::RpcServiceMethod* registered_method,
+                          ServerInterface* server, ServerContext* context,
                           internal::ServerAsyncStreamingInterface* stream,
                           CompletionQueue* call_cq,
                           ServerCompletionQueue* notification_cq, void* tag)
-        : RegisteredAsyncRequest(server, context, stream, call_cq, tag) {
-      IssueRequest(registered_method, nullptr, notification_cq);
+        : RegisteredAsyncRequest(server, context, stream, call_cq,
+                                 notification_cq, tag,
+                                 registered_method->name()) {
+      IssueRequest(registered_method->server_tag(), nullptr, notification_cq);
     }
 
     // uses RegisteredAsyncRequest::FinalizeResult
@@ -194,13 +219,15 @@ class ServerInterface : public internal::CallHook {
   template <class Message>
   class PayloadAsyncRequest final : public RegisteredAsyncRequest {
    public:
-    PayloadAsyncRequest(void* registered_method, ServerInterface* server,
-                        ServerContext* context,
+    PayloadAsyncRequest(internal::RpcServiceMethod* registered_method,
+                        ServerInterface* server, ServerContext* context,
                         internal::ServerAsyncStreamingInterface* stream,
                         CompletionQueue* call_cq,
                         ServerCompletionQueue* notification_cq, void* tag,
                         Message* request)
-        : RegisteredAsyncRequest(server, context, stream, call_cq, tag),
+        : RegisteredAsyncRequest(server, context, stream, call_cq,
+                                 notification_cq, tag,
+                                 registered_method->name()),
           registered_method_(registered_method),
           server_(server),
           context_(context),
@@ -209,7 +236,8 @@ class ServerInterface : public internal::CallHook {
           notification_cq_(notification_cq),
           tag_(tag),
           request_(request) {
-      IssueRequest(registered_method, payload_.bbuf_ptr(), notification_cq);
+      IssueRequest(registered_method->server_tag(), payload_.bbuf_ptr(),
+                   notification_cq);
     }
 
     ~PayloadAsyncRequest() {
@@ -217,6 +245,10 @@ class ServerInterface : public internal::CallHook {
     }
 
     bool FinalizeResult(void** tag, bool* status) override {
+      /* If we are done intercepting, then there is nothing more for us to do */
+      if (done_intercepting_) {
+        return RegisteredAsyncRequest::FinalizeResult(tag, status);
+      }
       if (*status) {
         if (!payload_.Valid() || !SerializationTraits<Message>::Deserialize(
                                       payload_.bbuf_ptr(), request_)
@@ -235,15 +267,20 @@ class ServerInterface : public internal::CallHook {
           return false;
         }
       }
+      /* Set interception point for recv message */
+      interceptor_methods_.AddInterceptionHookPoint(
+          experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
+      interceptor_methods_.SetRecvMessage(request_);
       return RegisteredAsyncRequest::FinalizeResult(tag, status);
     }
 
    private:
-    void* const registered_method_;
+    internal::RpcServiceMethod* const registered_method_;
     ServerInterface* const server_;
     ServerContext* const context_;
     internal::ServerAsyncStreamingInterface* const stream_;
     CompletionQueue* const call_cq_;
+
     ServerCompletionQueue* const notification_cq_;
     void* const tag_;
     Message* const request_;
@@ -272,9 +309,8 @@ class ServerInterface : public internal::CallHook {
                         ServerCompletionQueue* notification_cq, void* tag,
                         Message* message) {
     GPR_CODEGEN_ASSERT(method);
-    new PayloadAsyncRequest<Message>(method->server_tag(), this, context,
-                                     stream, call_cq, notification_cq, tag,
-                                     message);
+    new PayloadAsyncRequest<Message>(method, this, context, stream, call_cq,
+                                     notification_cq, tag, message);
   }
 
   void RequestAsyncCall(internal::RpcServiceMethod* method,
@@ -283,8 +319,8 @@ class ServerInterface : public internal::CallHook {
                         CompletionQueue* call_cq,
                         ServerCompletionQueue* notification_cq, void* tag) {
     GPR_CODEGEN_ASSERT(method);
-    new NoPayloadAsyncRequest(method->server_tag(), this, context, stream,
-                              call_cq, notification_cq, tag);
+    new NoPayloadAsyncRequest(method, this, context, stream, call_cq,
+                              notification_cq, tag);
   }
 
   void RequestAsyncGenericCall(GenericServerContext* context,
@@ -295,6 +331,28 @@ class ServerInterface : public internal::CallHook {
     new GenericAsyncRequest(this, context, stream, call_cq, notification_cq,
                             tag, true);
   }
+
+ private:
+  // EXPERIMENTAL
+  // Getter method for the vector of interceptor factory objects.
+  // Returns a nullptr (rather than being pure) since this is a new method and
+  // adding a new pure method to an interface would be a breaking change (even
+  // though this is private and non-API)
+  virtual std::vector<
+      std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>*
+  interceptor_creators() {
+    return nullptr;
+  }
+
+  // EXPERIMENTAL
+  // A method to get the callbackable completion queue associated with this
+  // server. If the return value is nullptr, this server doesn't support
+  // callback operations.
+  // TODO(vjpai): Consider a better default like using a global CQ
+  // Returns nullptr (rather than being pure) since this is a post-1.0 method
+  // and adding a new pure method to an interface would be a breaking change
+  // (even though this is private and non-API)
+  virtual CompletionQueue* CallbackCQ() { return nullptr; }
 };
 
 }  // namespace grpc

include/grpcpp/impl/codegen/service_type.h

@@ -71,7 +71,20 @@ class Service {
 
   bool has_synchronous_methods() const {
     for (auto it = methods_.begin(); it != methods_.end(); ++it) {
-      if (*it && (*it)->handler() != nullptr) {
+      if (*it &&
+          (*it)->api_type() == internal::RpcServiceMethod::ApiType::SYNC) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  bool has_callback_methods() const {
+    for (auto it = methods_.begin(); it != methods_.end(); ++it) {
+      if (*it && ((*it)->api_type() ==
+                      internal::RpcServiceMethod::ApiType::CALL_BACK ||
+                  (*it)->api_type() ==
+                      internal::RpcServiceMethod::ApiType::RAW_CALL_BACK)) {
         return true;
       }
     }
@@ -88,6 +101,43 @@ class Service {
   }
 
  protected:
+  // TODO(vjpai): Promote experimental contents once callback API is accepted
+  class experimental_type {
+   public:
+    explicit experimental_type(Service* service) : service_(service) {}
+
+    void MarkMethodCallback(int index, internal::MethodHandler* handler) {
+      // This does not have to be a hard error, however no one has approached us
+      // with a use case yet. Please file an issue if you believe you have one.
+      size_t idx = static_cast<size_t>(index);
+      GPR_CODEGEN_ASSERT(
+          service_->methods_[idx].get() != nullptr &&
+          "Cannot mark the method as 'callback' because it has already been "
+          "marked as 'generic'.");
+      service_->methods_[idx]->SetHandler(handler);
+      service_->methods_[idx]->SetServerApiType(
+          internal::RpcServiceMethod::ApiType::CALL_BACK);
+    }
+
+    void MarkMethodRawCallback(int index, internal::MethodHandler* handler) {
+      // This does not have to be a hard error, however no one has approached us
+      // with a use case yet. Please file an issue if you believe you have one.
+      size_t idx = static_cast<size_t>(index);
+      GPR_CODEGEN_ASSERT(
+          service_->methods_[idx].get() != nullptr &&
+          "Cannot mark the method as 'raw callback' because it has already "
+          "been marked as 'generic'.");
+      service_->methods_[idx]->SetHandler(handler);
+      service_->methods_[idx]->SetServerApiType(
+          internal::RpcServiceMethod::ApiType::RAW_CALL_BACK);
+    }
+
+   private:
+    Service* service_;
+  };
+
+  experimental_type experimental() { return experimental_type(this); }
+
   template <class Message>
   void RequestAsyncUnary(int index, ServerContext* context, Message* request,
                          internal::ServerAsyncStreamingInterface* stream,
@@ -138,8 +188,7 @@ class Service {
         methods_[idx].get() != nullptr &&
         "Cannot mark the method as 'async' because it has already been "
         "marked as 'generic'.");
-    methods_[idx]->SetServerAsyncType(
-        internal::RpcServiceMethod::AsyncType::ASYNC);
+    methods_[idx]->SetServerApiType(internal::RpcServiceMethod::ApiType::ASYNC);
   }
 
   void MarkMethodRaw(int index) {
@@ -149,8 +198,7 @@ class Service {
     GPR_CODEGEN_ASSERT(methods_[idx].get() != nullptr &&
                        "Cannot mark the method as 'raw' because it has already "
                        "been marked as 'generic'.");
-    methods_[idx]->SetServerAsyncType(
-        internal::RpcServiceMethod::AsyncType::RAW);
+    methods_[idx]->SetServerApiType(internal::RpcServiceMethod::ApiType::RAW);
   }
 
   void MarkMethodGeneric(int index) {

include/grpcpp/impl/codegen/sync_stream.h

@@ -250,7 +250,7 @@ class ClientReader final : public ClientReaderInterface<R> {
                                 ::grpc::internal::CallOpSendMessage,
                                 ::grpc::internal::CallOpClientSendClose>
         ops;
-    ops.SendInitialMetadata(context->send_initial_metadata_,
+    ops.SendInitialMetadata(&context->send_initial_metadata_,
                             context->initial_metadata_flags());
     // TODO(ctiller): don't assert
     GPR_CODEGEN_ASSERT(ops.SendMessage(request).ok());
@@ -327,7 +327,7 @@ class ClientWriter : public ClientWriterInterface<W> {
       ops.ClientSendClose();
     }
     if (context_->initial_metadata_corked_) {
-      ops.SendInitialMetadata(context_->send_initial_metadata_,
+      ops.SendInitialMetadata(&context_->send_initial_metadata_,
                               context_->initial_metadata_flags());
       context_->set_initial_metadata_corked(false);
     }
@@ -386,7 +386,7 @@ class ClientWriter : public ClientWriterInterface<W> {
     if (!context_->initial_metadata_corked_) {
       ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
           ops;
-      ops.SendInitialMetadata(context->send_initial_metadata_,
+      ops.SendInitialMetadata(&context->send_initial_metadata_,
                               context->initial_metadata_flags());
       call_.PerformOps(&ops);
       cq_.Pluck(&ops);
@@ -498,7 +498,7 @@ class ClientReaderWriter final : public ClientReaderWriterInterface<W, R> {
       ops.ClientSendClose();
     }
     if (context_->initial_metadata_corked_) {
-      ops.SendInitialMetadata(context_->send_initial_metadata_,
+      ops.SendInitialMetadata(&context_->send_initial_metadata_,
                               context_->initial_metadata_flags());
       context_->set_initial_metadata_corked(false);
     }
@@ -557,7 +557,7 @@ class ClientReaderWriter final : public ClientReaderWriterInterface<W, R> {
     if (!context_->initial_metadata_corked_) {
       ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
           ops;
-      ops.SendInitialMetadata(context->send_initial_metadata_,
+      ops.SendInitialMetadata(&context->send_initial_metadata_,
                               context->initial_metadata_flags());
       call_.PerformOps(&ops);
       cq_.Pluck(&ops);
@@ -583,7 +583,7 @@ class ServerReader final : public ServerReaderInterface<R> {
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     internal::CallOpSet<internal::CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(ctx_->initial_metadata_,
+    ops.SendInitialMetadata(&ctx_->initial_metadata_,
                             ctx_->initial_metadata_flags());
     if (ctx_->compression_level_set()) {
       ops.set_compression_level(ctx_->compression_level());
@@ -635,7 +635,7 @@ class ServerWriter final : public ServerWriterInterface<W> {
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     internal::CallOpSet<internal::CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(ctx_->initial_metadata_,
+    ops.SendInitialMetadata(&ctx_->initial_metadata_,
                             ctx_->initial_metadata_flags());
     if (ctx_->compression_level_set()) {
       ops.set_compression_level(ctx_->compression_level());
@@ -660,7 +660,7 @@ class ServerWriter final : public ServerWriterInterface<W> {
       return false;
     }
     if (!ctx_->sent_initial_metadata_) {
-      ctx_->pending_ops_.SendInitialMetadata(ctx_->initial_metadata_,
+      ctx_->pending_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                              ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         ctx_->pending_ops_.set_compression_level(ctx_->compression_level());
@@ -708,7 +708,7 @@ class ServerReaderWriterBody final {
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     CallOpSet<CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(ctx_->initial_metadata_,
+    ops.SendInitialMetadata(&ctx_->initial_metadata_,
                             ctx_->initial_metadata_flags());
     if (ctx_->compression_level_set()) {
       ops.set_compression_level(ctx_->compression_level());
@@ -738,7 +738,7 @@ class ServerReaderWriterBody final {
       return false;
     }
     if (!ctx_->sent_initial_metadata_) {
-      ctx_->pending_ops_.SendInitialMetadata(ctx_->initial_metadata_,
+      ctx_->pending_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                              ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
         ctx_->pending_ops_.set_compression_level(ctx_->compression_level());

include/grpcpp/opencensus.h

@@ -19,10 +19,6 @@
 #ifndef GRPCPP_OPENCENSUS_H
 #define GRPCPP_OPENCENSUS_H
 
-#ifndef GRPC_BAZEL_BUILD
-#error OpenCensus for gRPC is only supported when building with bazel.
-#endif
-
 #include "opencensus/trace/span.h"
 
 namespace grpc {

include/grpcpp/server.h

@@ -174,7 +174,11 @@ class Server : public ServerInterface, private GrpcLibraryCodegen {
          std::shared_ptr<std::vector<std::unique_ptr<ServerCompletionQueue>>>
              sync_server_cqs,
          int min_pollers, int max_pollers, int sync_cq_timeout_msec,
-         grpc_resource_quota* server_rq = nullptr);
+         grpc_resource_quota* server_rq = nullptr,
+         std::vector<
+             std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>
+             interceptor_creators = std::vector<std::unique_ptr<
+                 experimental::ServerInterceptorFactoryInterface>>());
 
   /// Start the server.
   ///
@@ -187,11 +191,17 @@ class Server : public ServerInterface, private GrpcLibraryCodegen {
   grpc_server* server() override { return server_; };
 
  private:
+  std::vector<std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>*
+  interceptor_creators() override {
+    return &interceptor_creators_;
+  }
+
   friend class AsyncGenericService;
   friend class ServerBuilder;
   friend class ServerInitializer;
 
   class SyncRequest;
+  class CallbackRequest;
   class UnimplementedAsyncRequest;
   class UnimplementedAsyncResponse;
 
@@ -214,8 +224,18 @@ class Server : public ServerInterface, private GrpcLibraryCodegen {
     return max_receive_message_size_;
   };
 
+  CompletionQueue* CallbackCQ() override;
+
   ServerInitializer* initializer();
 
+  // A vector of interceptor factory objects.
+  // This should be destroyed after health_check_service_ and this requirement
+  // is satisfied by declaring interceptor_creators_ before
+  // health_check_service_. (C++ mandates that member objects be destroyed in
+  // the reverse order of initialization.)
+  std::vector<std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>
+      interceptor_creators_;
+
   const int max_receive_message_size_;
 
   /// The following completion queues are ONLY used in case of Sync API
@@ -228,6 +248,9 @@ class Server : public ServerInterface, private GrpcLibraryCodegen {
   /// the \a sync_server_cqs)
   std::vector<std::unique_ptr<SyncRequestThreadManager>> sync_req_mgrs_;
 
+  /// Outstanding callback requests
+  std::vector<std::unique_ptr<CallbackRequest>> callback_reqs_;
+
   // Server status
   std::mutex mu_;
   bool started_;
@@ -251,6 +274,13 @@ class Server : public ServerInterface, private GrpcLibraryCodegen {
 
   // A special handler for resource exhausted in sync case
   std::unique_ptr<internal::MethodHandler> resource_exhausted_handler_;
+
+  // callback_cq_ references the callbackable completion queue associated
+  // with this server (if any). It is set on the first call to CallbackCQ().
+  // It is _not owned_ by the server; ownership belongs with its internal
+  // shutdown callback tag (invoked when the CQ is fully shutdown).
+  // It is protected by mu_
+  CompletionQueue* callback_cq_ = nullptr;
 };
 
 }  // namespace grpc

include/grpcpp/server_builder.h

@@ -28,6 +28,7 @@
 #include <grpc/support/cpu.h>
 #include <grpc/support/workaround_list.h>
 #include <grpcpp/impl/channel_argument_option.h>
+#include <grpcpp/impl/codegen/server_interceptor.h>
 #include <grpcpp/impl/server_builder_option.h>
 #include <grpcpp/impl/server_builder_plugin.h>
 #include <grpcpp/support/config.h>
@@ -212,6 +213,29 @@ class ServerBuilder {
   /// doc/workarounds.md.
   ServerBuilder& EnableWorkaround(grpc_workaround_list id);
 
+  /// NOTE: class experimental_type is not part of the public API of this class.
+  /// TODO(yashykt): Integrate into public API when this is no longer
+  /// experimental.
+  class experimental_type {
+   public:
+    explicit experimental_type(ServerBuilder* builder) : builder_(builder) {}
+
+    void SetInterceptorCreators(
+        std::vector<
+            std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>
+            interceptor_creators) {
+      builder_->interceptor_creators_ = std::move(interceptor_creators);
+    }
+
+   private:
+    ServerBuilder* builder_;
+  };
+
+  /// NOTE: The function experimental() is not stable public API. It is a view
+  /// to the experimental components of this class. It may be changed or removed
+  /// at any time.
+  experimental_type experimental() { return experimental_type(this); }
+
  protected:
   /// Experimental, to be deprecated
   struct Port {
@@ -297,6 +321,8 @@ class ServerBuilder {
     grpc_compression_algorithm algorithm;
   } maybe_default_compression_algorithm_;
   uint32_t enabled_compression_algorithms_bitset_;
+  std::vector<std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>
+      interceptor_creators_;
 };
 
 }  // namespace grpc

include/grpcpp/support/server_callback.h

@@ -0,0 +1,24 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_SUPPORT_SERVER_CALLBACK_H
+#define GRPCPP_SUPPORT_SERVER_CALLBACK_H
+
+#include <grpcpp/impl/codegen/server_callback.h>
+
+#endif  // GRPCPP_SUPPORT_SERVER_CALLBACK_H

package.xml

@@ -213,6 +213,7 @@
     <file baseinstalldir="/" name="src/core/ext/filters/http/message_compress/message_compress_filter.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/http/server/http_server_filter.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/context/security_context.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/credentials/alts/alts_credentials.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/credentials/composite/composite_credentials.h" role="src" />
@@ -227,11 +228,14 @@
     <file baseinstalldir="/" name="src/core/lib/security/credentials/oauth2/oauth2_credentials.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/credentials/plugin/plugin_credentials.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/credentials/ssl/ssl_credentials.h" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/security/security_connector/alts_security_connector.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/alts/alts_security_connector.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/fake/fake_security_connector.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/security_connector/load_system_roots.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/security_connector/load_system_roots_linux.h" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/security/security_connector/local_security_connector.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/local/local_security_connector.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/security_connector/security_connector.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/ssl/ssl_security_connector.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/ssl_utils.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/transport/auth_filters.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/transport/secure_endpoint.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/transport/security_handshaker.h" role="src" />
@@ -276,6 +280,7 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/client_channel_channelz.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/client_channel_factory.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/connector.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/health/health_check_client.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/http_connect_handshaker.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/http_proxy.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy.h" role="src" />
@@ -291,8 +296,8 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/retry_throttle.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/subchannel.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/subchannel_index.h" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/uri_parser.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/deadline/deadline_filter.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/health/health.pb.h" role="src" />
     <file baseinstalldir="/" name="src/core/tsi/alts_transport_security.h" role="src" />
     <file baseinstalldir="/" name="src/core/tsi/fake_transport_security.h" role="src" />
     <file baseinstalldir="/" name="src/core/tsi/local_transport_security.h" role="src" />
@@ -438,15 +443,19 @@
     <file baseinstalldir="/" name="src/core/lib/transport/timeout_encoding.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/transport.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/transport_impl.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/uri/uri_parser.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/debug/trace.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/subchannel_list.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h" role="src" />
@@ -606,6 +615,7 @@
     <file baseinstalldir="/" name="src/core/lib/transport/timeout_encoding.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/transport.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/transport_op_string.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/uri/uri_parser.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/debug/trace.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/bin_decoder.cc" role="src" />
@@ -652,11 +662,14 @@
     <file baseinstalldir="/" name="src/core/lib/security/credentials/oauth2/oauth2_credentials.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/credentials/plugin/plugin_credentials.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/credentials/ssl/ssl_credentials.cc" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/security/security_connector/alts_security_connector.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/alts/alts_security_connector.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/fake/fake_security_connector.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/security_connector/load_system_roots_fallback.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/security_connector/load_system_roots_linux.cc" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/security/security_connector/local_security_connector.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/local/local_security_connector.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/security_connector/security_connector.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/ssl/ssl_security_connector.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/security/security_connector/ssl_utils.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/transport/client_auth_filter.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/transport/secure_endpoint.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/security/transport/security_handshaker.cc" role="src" />
@@ -711,6 +724,7 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/client_channel_factory.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/client_channel_plugin.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/connector.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/health/health_check_client.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/http_connect_handshaker.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/http_proxy.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy.cc" role="src" />
@@ -725,8 +739,8 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/retry_throttle.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/subchannel.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/subchannel_index.cc" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/uri_parser.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/deadline/deadline_filter.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/health/health.pb.c" role="src" />
     <file baseinstalldir="/" name="src/core/tsi/alts_transport_security.cc" role="src" />
     <file baseinstalldir="/" name="src/core/tsi/fake_transport_security.cc" role="src" />
     <file baseinstalldir="/" name="src/core/tsi/local_transport_security.cc" role="src" />
@@ -746,10 +760,14 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/duration.pb.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/google/protobuf/timestamp.pb.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc" role="src" />

setup.py

@@ -87,19 +87,19 @@ BUILD_WITH_CYTHON = os.environ.get('GRPC_PYTHON_BUILD_WITH_CYTHON', False)
 
 # Export this variable to use the system installation of openssl. You need to
 # have the header files installed (in /usr/include/openssl) and during
-# runtime, the shared libary must be installed
+# runtime, the shared library must be installed
 BUILD_WITH_SYSTEM_OPENSSL = os.environ.get('GRPC_PYTHON_BUILD_SYSTEM_OPENSSL',
                                            False)
 
 # Export this variable to use the system installation of zlib. You need to
 # have the header files installed (in /usr/include/) and during
-# runtime, the shared libary must be installed
+# runtime, the shared library must be installed
 BUILD_WITH_SYSTEM_ZLIB = os.environ.get('GRPC_PYTHON_BUILD_SYSTEM_ZLIB',
                                         False)
 
 # Export this variable to use the system installation of cares. You need to
 # have the header files installed (in /usr/include/) and during
-# runtime, the shared libary must be installed
+# runtime, the shared library must be installed
 BUILD_WITH_SYSTEM_CARES = os.environ.get('GRPC_PYTHON_BUILD_SYSTEM_CARES',
                                          False)
 
@@ -202,7 +202,7 @@ DEFINE_MACROS = (
     ('OPENSSL_NO_ASM', 1), ('_WIN32_WINNT', 0x600),
     ('GPR_BACKWARDS_COMPATIBILITY_MODE', 1))
 if "win32" in sys.platform:
-  # TODO(zyc): Re-enble c-ares on x64 and x86 windows after fixing the
+  # TODO(zyc): Re-enable c-ares on x64 and x86 windows after fixing the
   # ares_library_init compilation issue
   DEFINE_MACROS += (('WIN32_LEAN_AND_MEAN', 1), ('CARES_STATICLIB', 1),
                     ('GRPC_ARES', 0), ('NTDDI_VERSION', 0x06000000),

src/compiler/cpp_generator.cc

@@ -135,6 +135,7 @@ grpc::string GetHeaderIncludes(grpc_generator::File* file,
         "grpcpp/impl/codegen/method_handler_impl.h",
         "grpcpp/impl/codegen/proto_utils.h",
         "grpcpp/impl/codegen/rpc_method.h",
+        "grpcpp/impl/codegen/server_callback.h",
         "grpcpp/impl/codegen/service_type.h",
         "grpcpp/impl/codegen/status.h",
         "grpcpp/impl/codegen/stub_options.h",
@@ -700,9 +701,9 @@ void PrintHeaderServerMethodSync(grpc_generator::Printer* printer,
   printer->Print(method->GetTrailingComments("//").c_str());
 }
 
-// Helper generator. Disabled the sync API for Request and Response, then adds
+// Helper generator. Disables the sync API for Request and Response, then adds
 // in an async API for RealRequest and RealResponse types. This is to be used
-// to generate async and raw APIs.
+// to generate async and raw async APIs.
 void PrintHeaderServerAsyncMethodsHelper(
     grpc_generator::Printer* printer, const grpc_generator::Method* method,
     std::map<grpc::string, grpc::string>* vars) {
@@ -829,6 +830,170 @@ void PrintHeaderServerMethodAsync(grpc_generator::Printer* printer,
   printer->Print(*vars, "};\n");
 }
 
+// Helper generator. Disables the sync API for Request and Response, then adds
+// in a callback API for RealRequest and RealResponse types. This is to be used
+// to generate callback and raw callback APIs.
+void PrintHeaderServerCallbackMethodsHelper(
+    grpc_generator::Printer* printer, const grpc_generator::Method* method,
+    std::map<grpc::string, grpc::string>* vars) {
+  if (method->NoStreaming()) {
+    printer->Print(
+        *vars,
+        "// disable synchronous version of this method\n"
+        "::grpc::Status $Method$("
+        "::grpc::ServerContext* context, const $Request$* request, "
+        "$Response$* response) override {\n"
+        "  abort();\n"
+        "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
+        "}\n");
+    printer->Print(
+        *vars,
+        "virtual void $Method$("
+        "::grpc::ServerContext* context, const $RealRequest$* request, "
+        "$RealResponse$* response, "
+        "::grpc::experimental::ServerCallbackRpcController* "
+        "controller) { controller->Finish(::grpc::Status("
+        "::grpc::StatusCode::UNIMPLEMENTED, \"\")); }\n");
+  } else if (ClientOnlyStreaming(method)) {
+    printer->Print(
+        *vars,
+        "// disable synchronous version of this method\n"
+        "::grpc::Status $Method$("
+        "::grpc::ServerContext* context, "
+        "::grpc::ServerReader< $Request$>* reader, "
+        "$Response$* response) override {\n"
+        "  abort();\n"
+        "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
+        "}\n");
+  } else if (ServerOnlyStreaming(method)) {
+    printer->Print(
+        *vars,
+        "// disable synchronous version of this method\n"
+        "::grpc::Status $Method$("
+        "::grpc::ServerContext* context, const $Request$* request, "
+        "::grpc::ServerWriter< $Response$>* writer) override "
+        "{\n"
+        "  abort();\n"
+        "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
+        "}\n");
+  } else if (method->BidiStreaming()) {
+    printer->Print(
+        *vars,
+        "// disable synchronous version of this method\n"
+        "::grpc::Status $Method$("
+        "::grpc::ServerContext* context, "
+        "::grpc::ServerReaderWriter< $Response$, $Request$>* stream) "
+        " override {\n"
+        "  abort();\n"
+        "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
+        "}\n");
+  }
+}
+
+void PrintHeaderServerMethodCallback(
+    grpc_generator::Printer* printer, const grpc_generator::Method* method,
+    std::map<grpc::string, grpc::string>* vars) {
+  (*vars)["Method"] = method->name();
+  // These will be disabled
+  (*vars)["Request"] = method->input_type_name();
+  (*vars)["Response"] = method->output_type_name();
+  // These will be used for the callback API
+  (*vars)["RealRequest"] = method->input_type_name();
+  (*vars)["RealResponse"] = method->output_type_name();
+  printer->Print(*vars, "template <class BaseClass>\n");
+  printer->Print(
+      *vars,
+      "class ExperimentalWithCallbackMethod_$Method$ : public BaseClass {\n");
+  printer->Print(
+      " private:\n"
+      "  void BaseClassMustBeDerivedFromService(const Service *service) {}\n");
+  printer->Print(" public:\n");
+  printer->Indent();
+  printer->Print(*vars, "ExperimentalWithCallbackMethod_$Method$() {\n");
+  if (method->NoStreaming()) {
+    printer->Print(
+        *vars,
+        "  ::grpc::Service::experimental().MarkMethodCallback($Idx$,\n"
+        "    new ::grpc::internal::CallbackUnaryHandler< "
+        "ExperimentalWithCallbackMethod_$Method$<BaseClass>, $RealRequest$, "
+        "$RealResponse$>(\n"
+        "      [this](::grpc::ServerContext* context,\n"
+        "             const $RealRequest$* request,\n"
+        "             $RealResponse$* response,\n"
+        "             ::grpc::experimental::ServerCallbackRpcController* "
+        "controller) {\n"
+        "               this->$"
+        "Method$(context, request, response, controller);\n"
+        "             }, this));\n");
+  } else if (ClientOnlyStreaming(method)) {
+    // TODO(vjpai): Add in code generation for all streaming methods
+  } else if (ServerOnlyStreaming(method)) {
+    // TODO(vjpai): Add in code generation for all streaming methods
+  } else if (method->BidiStreaming()) {
+    // TODO(vjpai): Add in code generation for all streaming methods
+  }
+  printer->Print(*vars, "}\n");
+  printer->Print(*vars,
+                 "~ExperimentalWithCallbackMethod_$Method$() override {\n"
+                 "  BaseClassMustBeDerivedFromService(this);\n"
+                 "}\n");
+  PrintHeaderServerCallbackMethodsHelper(printer, method, vars);
+  printer->Outdent();
+  printer->Print(*vars, "};\n");
+}
+
+void PrintHeaderServerMethodRawCallback(
+    grpc_generator::Printer* printer, const grpc_generator::Method* method,
+    std::map<grpc::string, grpc::string>* vars) {
+  (*vars)["Method"] = method->name();
+  // These will be disabled
+  (*vars)["Request"] = method->input_type_name();
+  (*vars)["Response"] = method->output_type_name();
+  // These will be used for raw API
+  (*vars)["RealRequest"] = "::grpc::ByteBuffer";
+  (*vars)["RealResponse"] = "::grpc::ByteBuffer";
+  printer->Print(*vars, "template <class BaseClass>\n");
+  printer->Print(*vars,
+                 "class ExperimentalWithRawCallbackMethod_$Method$ : public "
+                 "BaseClass {\n");
+  printer->Print(
+      " private:\n"
+      "  void BaseClassMustBeDerivedFromService(const Service *service) {}\n");
+  printer->Print(" public:\n");
+  printer->Indent();
+  printer->Print(*vars, "ExperimentalWithRawCallbackMethod_$Method$() {\n");
+  if (method->NoStreaming()) {
+    printer->Print(
+        *vars,
+        "  ::grpc::Service::experimental().MarkMethodRawCallback($Idx$,\n"
+        "    new ::grpc::internal::CallbackUnaryHandler< "
+        "ExperimentalWithRawCallbackMethod_$Method$<BaseClass>, $RealRequest$, "
+        "$RealResponse$>(\n"
+        "      [this](::grpc::ServerContext* context,\n"
+        "             const $RealRequest$* request,\n"
+        "             $RealResponse$* response,\n"
+        "             ::grpc::experimental::ServerCallbackRpcController* "
+        "controller) {\n"
+        "               this->$"
+        "Method$(context, request, response, controller);\n"
+        "             }, this));\n");
+  } else if (ClientOnlyStreaming(method)) {
+    // TODO(vjpai): Add in code generation for all streaming methods
+  } else if (ServerOnlyStreaming(method)) {
+    // TODO(vjpai): Add in code generation for all streaming methods
+  } else if (method->BidiStreaming()) {
+    // TODO(vjpai): Add in code generation for all streaming methods
+  }
+  printer->Print(*vars, "}\n");
+  printer->Print(*vars,
+                 "~ExperimentalWithRawCallbackMethod_$Method$() override {\n"
+                 "  BaseClassMustBeDerivedFromService(this);\n"
+                 "}\n");
+  PrintHeaderServerCallbackMethodsHelper(printer, method, vars);
+  printer->Outdent();
+  printer->Print(*vars, "};\n");
+}
+
 void PrintHeaderServerMethodStreamedUnary(
     grpc_generator::Printer* printer, const grpc_generator::Method* method,
     std::map<grpc::string, grpc::string>* vars) {
@@ -1137,7 +1302,7 @@ void PrintHeaderService(grpc_generator::Printer* printer,
   printer->Print("typedef ");
 
   for (int i = 0; i < service->method_count(); ++i) {
-    (*vars)["method_name"] = service->method(i).get()->name();
+    (*vars)["method_name"] = service->method(i)->name();
     printer->Print(*vars, "WithAsyncMethod_$method_name$<");
   }
   printer->Print("Service");
@@ -1146,6 +1311,24 @@ void PrintHeaderService(grpc_generator::Printer* printer,
   }
   printer->Print(" AsyncService;\n");
 
+  // Server side - Callback
+  for (int i = 0; i < service->method_count(); ++i) {
+    (*vars)["Idx"] = as_string(i);
+    PrintHeaderServerMethodCallback(printer, service->method(i).get(), vars);
+  }
+
+  printer->Print("typedef ");
+
+  for (int i = 0; i < service->method_count(); ++i) {
+    (*vars)["method_name"] = service->method(i)->name();
+    printer->Print(*vars, "ExperimentalWithCallbackMethod_$method_name$<");
+  }
+  printer->Print("Service");
+  for (int i = 0; i < service->method_count(); ++i) {
+    printer->Print(" >");
+  }
+  printer->Print(" ExperimentalCallbackService;\n");
+
   // Server side - Generic
   for (int i = 0; i < service->method_count(); ++i) {
     (*vars)["Idx"] = as_string(i);
@@ -1158,6 +1341,12 @@ void PrintHeaderService(grpc_generator::Printer* printer,
     PrintHeaderServerMethodRaw(printer, service->method(i).get(), vars);
   }
 
+  // Server side - Raw Callback
+  for (int i = 0; i < service->method_count(); ++i) {
+    (*vars)["Idx"] = as_string(i);
+    PrintHeaderServerMethodRawCallback(printer, service->method(i).get(), vars);
+  }
+
   // Server side - Streamed Unary
   for (int i = 0; i < service->method_count(); ++i) {
     (*vars)["Idx"] = as_string(i);
@@ -1167,7 +1356,7 @@ void PrintHeaderService(grpc_generator::Printer* printer,
 
   printer->Print("typedef ");
   for (int i = 0; i < service->method_count(); ++i) {
-    (*vars)["method_name"] = service->method(i).get()->name();
+    (*vars)["method_name"] = service->method(i)->name();
     if (service->method(i)->NoStreaming()) {
       printer->Print(*vars, "WithStreamedUnaryMethod_$method_name$<");
     }
@@ -1189,7 +1378,7 @@ void PrintHeaderService(grpc_generator::Printer* printer,
 
   printer->Print("typedef ");
   for (int i = 0; i < service->method_count(); ++i) {
-    (*vars)["method_name"] = service->method(i).get()->name();
+    (*vars)["method_name"] = service->method(i)->name();
     auto method = service->method(i);
     if (ServerOnlyStreaming(method.get())) {
       printer->Print(*vars, "WithSplitStreamingMethod_$method_name$<");
@@ -1207,7 +1396,7 @@ void PrintHeaderService(grpc_generator::Printer* printer,
   // Server side - typedef for controlled both unary and server-side streaming
   printer->Print("typedef ");
   for (int i = 0; i < service->method_count(); ++i) {
-    (*vars)["method_name"] = service->method(i).get()->name();
+    (*vars)["method_name"] = service->method(i)->name();
     auto method = service->method(i);
     if (ServerOnlyStreaming(method.get())) {
       printer->Print(*vars, "WithSplitStreamingMethod_$method_name$<");
@@ -1333,6 +1522,7 @@ grpc::string GetSourceIncludes(grpc_generator::File* file,
         "grpcpp/impl/codegen/client_callback.h",
         "grpcpp/impl/codegen/method_handler_impl.h",
         "grpcpp/impl/codegen/rpc_service_method.h",
+        "grpcpp/impl/codegen/server_callback.h",
         "grpcpp/impl/codegen/service_type.h",
         "grpcpp/impl/codegen/sync_stream.h"};
     std::vector<grpc::string> headers(headers_strs, array_end(headers_strs));
@@ -1577,7 +1767,7 @@ void PrintSourceService(grpc_generator::Printer* printer,
     printer->Print(*vars,
                    "static const char* $prefix$$Service$_method_names[] = {\n");
     for (int i = 0; i < service->method_count(); ++i) {
-      (*vars)["Method"] = service->method(i).get()->name();
+      (*vars)["Method"] = service->method(i)->name();
       printer->Print(*vars, "  \"/$Package$$Service$/$Method$\",\n");
     }
     printer->Print(*vars, "};\n\n");

src/core/ext/filters/client_channel/client_channel.cc

@@ -129,6 +129,10 @@ typedef struct client_channel_channel_data {
   grpc_core::UniquePtr<char> info_lb_policy_name;
   /** service config in JSON form */
   grpc_core::UniquePtr<char> info_service_config_json;
+  /* backpointer to grpc_channel's channelz node */
+  grpc_core::channelz::ClientChannelNode* channelz_channel;
+  /* caches if the last resolution event contained addresses */
+  bool previous_resolution_contained_addresses;
 } channel_data;
 
 typedef struct {
@@ -153,6 +157,23 @@ static void watch_lb_policy_locked(channel_data* chand,
                                    grpc_core::LoadBalancingPolicy* lb_policy,
                                    grpc_connectivity_state current_state);
 
+static const char* channel_connectivity_state_change_string(
+    grpc_connectivity_state state) {
+  switch (state) {
+    case GRPC_CHANNEL_IDLE:
+      return "Channel state change to IDLE";
+    case GRPC_CHANNEL_CONNECTING:
+      return "Channel state change to CONNECTING";
+    case GRPC_CHANNEL_READY:
+      return "Channel state change to READY";
+    case GRPC_CHANNEL_TRANSIENT_FAILURE:
+      return "Channel state change to TRANSIENT_FAILURE";
+    case GRPC_CHANNEL_SHUTDOWN:
+      return "Channel state change to SHUTDOWN";
+  }
+  GPR_UNREACHABLE_CODE(return "UNKNOWN");
+}
+
 static void set_channel_connectivity_state_locked(channel_data* chand,
                                                   grpc_connectivity_state state,
                                                   grpc_error* error,
@@ -177,6 +198,12 @@ static void set_channel_connectivity_state_locked(channel_data* chand,
     gpr_log(GPR_INFO, "chand=%p: setting connectivity state to %s", chand,
             grpc_connectivity_state_name(state));
   }
+  if (chand->channelz_channel != nullptr) {
+    chand->channelz_channel->AddTraceEvent(
+        grpc_core::channelz::ChannelTrace::Severity::Info,
+        grpc_slice_from_static_string(
+            channel_connectivity_state_change_string(state)));
+  }
   grpc_connectivity_state_set(&chand->state_tracker, state, error, reason);
 }
 
@@ -376,6 +403,8 @@ static void request_reresolution_locked(void* arg, grpc_error* error) {
   chand->lb_policy->SetReresolutionClosureLocked(&args->closure);
 }
 
+using TraceStringVector = grpc_core::InlinedVector<char*, 3>;
+
 // Creates a new LB policy, replacing any previous one.
 // If the new policy is created successfully, sets *connectivity_state and
 // *connectivity_error to its initial connectivity state; otherwise,
@@ -383,7 +412,7 @@ static void request_reresolution_locked(void* arg, grpc_error* error) {
 static void create_new_lb_policy_locked(
     channel_data* chand, char* lb_policy_name,
     grpc_connectivity_state* connectivity_state,
-    grpc_error** connectivity_error) {
+    grpc_error** connectivity_error, TraceStringVector* trace_strings) {
   grpc_core::LoadBalancingPolicy::Args lb_policy_args;
   lb_policy_args.combiner = chand->combiner;
   lb_policy_args.client_channel_factory = chand->client_channel_factory;
@@ -393,11 +422,21 @@ static void create_new_lb_policy_locked(
           lb_policy_name, lb_policy_args);
   if (GPR_UNLIKELY(new_lb_policy == nullptr)) {
     gpr_log(GPR_ERROR, "could not create LB policy \"%s\"", lb_policy_name);
+    if (chand->channelz_channel != nullptr) {
+      char* str;
+      gpr_asprintf(&str, "Could not create LB policy \'%s\'", lb_policy_name);
+      trace_strings->push_back(str);
+    }
   } else {
     if (grpc_client_channel_trace.enabled()) {
       gpr_log(GPR_INFO, "chand=%p: created new LB policy \"%s\" (%p)", chand,
               lb_policy_name, new_lb_policy.get());
     }
+    if (chand->channelz_channel != nullptr) {
+      char* str;
+      gpr_asprintf(&str, "Created new LB policy \'%s\'", lb_policy_name);
+      trace_strings->push_back(str);
+    }
     // Swap out the LB policy and update the fds in
     // chand->interested_parties.
     if (chand->lb_policy != nullptr) {
@@ -472,6 +511,51 @@ get_service_config_from_resolver_result_locked(channel_data* chand) {
   return grpc_core::UniquePtr<char>(gpr_strdup(service_config_json));
 }
 
+static void maybe_add_trace_message_for_address_changes_locked(
+    channel_data* chand, TraceStringVector* trace_strings) {
+  int resolution_contains_addresses = false;
+  const grpc_arg* channel_arg =
+      grpc_channel_args_find(chand->resolver_result, GRPC_ARG_LB_ADDRESSES);
+  if (channel_arg != nullptr && channel_arg->type == GRPC_ARG_POINTER) {
+    grpc_lb_addresses* addresses =
+        static_cast<grpc_lb_addresses*>(channel_arg->value.pointer.p);
+    if (addresses->num_addresses > 0) {
+      resolution_contains_addresses = true;
+    }
+  }
+  if (!resolution_contains_addresses &&
+      chand->previous_resolution_contained_addresses) {
+    trace_strings->push_back(gpr_strdup("Address list became empty"));
+  } else if (resolution_contains_addresses &&
+             !chand->previous_resolution_contained_addresses) {
+    trace_strings->push_back(gpr_strdup("Address list became non-empty"));
+  }
+  chand->previous_resolution_contained_addresses =
+      resolution_contains_addresses;
+}
+
+static void concatenate_and_add_channel_trace_locked(
+    channel_data* chand, TraceStringVector* trace_strings) {
+  if (!trace_strings->empty()) {
+    gpr_strvec v;
+    gpr_strvec_init(&v);
+    gpr_strvec_add(&v, gpr_strdup("Resolution event: "));
+    bool is_first = 1;
+    for (size_t i = 0; i < trace_strings->size(); ++i) {
+      if (!is_first) gpr_strvec_add(&v, gpr_strdup(", "));
+      is_first = false;
+      gpr_strvec_add(&v, (*trace_strings)[i]);
+    }
+    char* flat;
+    size_t flat_len = 0;
+    flat = gpr_strvec_flatten(&v, &flat_len);
+    chand->channelz_channel->AddTraceEvent(
+        grpc_core::channelz::ChannelTrace::Severity::Info,
+        grpc_slice_new(flat, flat_len, gpr_free));
+    gpr_strvec_destroy(&v);
+  }
+}
+
 // Callback invoked when a resolver result is available.
 static void on_resolver_result_changed_locked(void* arg, grpc_error* error) {
   channel_data* chand = static_cast<channel_data*>(arg);
@@ -493,6 +577,16 @@ static void on_resolver_result_changed_locked(void* arg, grpc_error* error) {
   }
   // Data used to set the channel's connectivity state.
   bool set_connectivity_state = true;
+  // We only want to trace the address resolution in the follow cases:
+  // (a) Address resolution resulted in service config change.
+  // (b) Address resolution that causes number of backends to go from
+  //     zero to non-zero.
+  // (c) Address resolution that causes number of backends to go from
+  //     non-zero to zero.
+  // (d) Address resolution that causes a new LB policy to be created.
+  //
+  // we track a list of strings to eventually be concatenated and traced.
+  TraceStringVector trace_strings;
   grpc_connectivity_state connectivity_state = GRPC_CHANNEL_TRANSIENT_FAILURE;
   grpc_error* connectivity_error =
       GRPC_ERROR_CREATE_FROM_STATIC_STRING("No load balancing policy");
@@ -527,11 +621,29 @@ static void on_resolver_result_changed_locked(void* arg, grpc_error* error) {
     } else {
       // Instantiate new LB policy.
       create_new_lb_policy_locked(chand, lb_policy_name.get(),
-                                  &connectivity_state, &connectivity_error);
+                                  &connectivity_state, &connectivity_error,
+                                  &trace_strings);
     }
     // Find service config.
     grpc_core::UniquePtr<char> service_config_json =
         get_service_config_from_resolver_result_locked(chand);
+    // Note: It's safe to use chand->info_service_config_json here without
+    // taking a lock on chand->info_mu, because this function is the
+    // only thing that modifies its value, and it can only be invoked
+    // once at any given time.
+    if (chand->channelz_channel != nullptr) {
+      if (((service_config_json == nullptr) !=
+           (chand->info_service_config_json == nullptr)) ||
+          (service_config_json != nullptr &&
+           strcmp(service_config_json.get(),
+                  chand->info_service_config_json.get()) != 0)) {
+        // TODO(ncteisen): might be worth somehow including a snippet of the
+        // config in the trace, at the risk of bloating the trace logs.
+        trace_strings.push_back(gpr_strdup("Service config changed"));
+      }
+      maybe_add_trace_message_for_address_changes_locked(chand, &trace_strings);
+      concatenate_and_add_channel_trace_locked(chand, &trace_strings);
+    }
     // Swap out the data used by cc_get_channel_info().
     gpr_mu_lock(&chand->info_mu);
     chand->info_lb_policy_name = std::move(lb_policy_name);
@@ -699,6 +811,8 @@ static grpc_error* cc_init_channel_elem(grpc_channel_element* elem,
   // Record enable_retries.
   arg = grpc_channel_args_find(args->channel_args, GRPC_ARG_ENABLE_RETRIES);
   chand->enable_retries = grpc_channel_arg_get_bool(arg, true);
+  chand->channelz_channel = nullptr;
+  chand->previous_resolution_contained_addresses = false;
   // Record client channel factory.
   arg = grpc_channel_args_find(args->channel_args,
                                GRPC_ARG_CLIENT_CHANNEL_FACTORY);
@@ -2194,9 +2308,9 @@ static void add_retriable_send_initial_metadata_op(
                                    .grpc_previous_rpc_attempts);
   }
   if (GPR_UNLIKELY(calld->num_attempts_completed > 0)) {
-    grpc_mdelem retry_md = grpc_mdelem_from_slices(
+    grpc_mdelem retry_md = grpc_mdelem_create(
         GRPC_MDSTR_GRPC_PREVIOUS_RPC_ATTEMPTS,
-        *retry_count_strings[calld->num_attempts_completed - 1]);
+        *retry_count_strings[calld->num_attempts_completed - 1], nullptr);
     grpc_error* error = grpc_metadata_batch_add_tail(
         &retry_state->send_initial_metadata,
         &retry_state->send_initial_metadata_storage[calld->send_initial_metadata
@@ -2837,6 +2951,27 @@ static void apply_service_config_to_call_locked(grpc_call_element* elem) {
   }
 }
 
+// If the channel is in TRANSIENT_FAILURE and the call is not
+// wait_for_ready=true, fails the call and returns true.
+static bool fail_call_if_in_transient_failure(grpc_call_element* elem) {
+  channel_data* chand = static_cast<channel_data*>(elem->channel_data);
+  call_data* calld = static_cast<call_data*>(elem->call_data);
+  grpc_transport_stream_op_batch* batch = calld->pending_batches[0].batch;
+  if (grpc_connectivity_state_check(&chand->state_tracker) ==
+          GRPC_CHANNEL_TRANSIENT_FAILURE &&
+      (batch->payload->send_initial_metadata.send_initial_metadata_flags &
+       GRPC_INITIAL_METADATA_WAIT_FOR_READY) == 0) {
+    pending_batches_fail(
+        elem,
+        grpc_error_set_int(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+                               "channel is in state TRANSIENT_FAILURE"),
+                           GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE),
+        true /* yield_call_combiner */);
+    return true;
+  }
+  return false;
+}
+
 // Invoked once resolver results are available.
 static void process_service_config_and_start_lb_pick_locked(
     grpc_call_element* elem) {
@@ -2844,6 +2979,9 @@ static void process_service_config_and_start_lb_pick_locked(
   // Only get service config data on the first attempt.
   if (GPR_LIKELY(calld->num_attempts_completed == 0)) {
     apply_service_config_to_call_locked(elem);
+    // Check this after applying service config, since it may have
+    // affected the call's wait_for_ready value.
+    if (fail_call_if_in_transient_failure(elem)) return;
   }
   // Start LB pick.
   grpc_core::LbPicker::StartLocked(elem);
@@ -3013,6 +3151,16 @@ static void start_pick_locked(void* arg, grpc_error* ignored) {
     // We do not yet have an LB policy, so wait for a resolver result.
     if (GPR_UNLIKELY(!chand->started_resolving)) {
       start_resolving_locked(chand);
+    } else {
+      // Normally, we want to do this check in
+      // process_service_config_and_start_lb_pick_locked(), so that we
+      // can honor the wait_for_ready setting in the service config.
+      // However, if the channel is in TRANSIENT_FAILURE at this point, that
+      // means that the resolver has returned a failure, so we're not going
+      // to get a service config right away.  In that case, we fail the
+      // call now based on the wait_for_ready value passed in from the
+      // application.
+      if (fail_call_if_in_transient_failure(elem)) return;
     }
     // Create a new waiter, which will delete itself when done.
     grpc_core::New<grpc_core::ResolverResultWaiter>(elem);
@@ -3208,6 +3356,12 @@ static void try_to_connect_locked(void* arg, grpc_error* error_ignored) {
   GRPC_CHANNEL_STACK_UNREF(chand->owning_stack, "try_to_connect");
 }
 
+void grpc_client_channel_set_channelz_node(
+    grpc_channel_element* elem, grpc_core::channelz::ClientChannelNode* node) {
+  channel_data* chand = static_cast<channel_data*>(elem->channel_data);
+  chand->channelz_channel = node;
+}
+
 void grpc_client_channel_populate_child_refs(
     grpc_channel_element* elem,
     grpc_core::channelz::ChildRefsList* child_subchannels,

src/core/ext/filters/client_channel/client_channel.h

@@ -40,6 +40,9 @@ extern grpc_core::TraceFlag grpc_client_channel_trace;
 
 extern const grpc_channel_filter grpc_client_channel_filter;
 
+void grpc_client_channel_set_channelz_node(
+    grpc_channel_element* elem, grpc_core::channelz::ClientChannelNode* node);
+
 void grpc_client_channel_populate_child_refs(
     grpc_channel_element* elem,
     grpc_core::channelz::ChildRefsList* child_subchannels,

src/core/ext/filters/client_channel/client_channel_channelz.cc

@@ -49,6 +49,7 @@ ClientChannelNode::ClientChannelNode(grpc_channel* channel,
     : ChannelNode(channel, channel_tracer_max_nodes, is_top_level_channel) {
   client_channel_ =
       grpc_channel_stack_last_element(grpc_channel_get_channel_stack(channel));
+  grpc_client_channel_set_channelz_node(client_channel_, this);
   GPR_ASSERT(client_channel_->filter == &grpc_client_channel_filter);
 }
 
@@ -127,7 +128,8 @@ void SubchannelNode::PopulateConnectivityState(grpc_json* json) {
   if (subchannel_ == nullptr) {
     state = GRPC_CHANNEL_SHUTDOWN;
   } else {
-    state = grpc_subchannel_check_connectivity(subchannel_, nullptr);
+    state = grpc_subchannel_check_connectivity(
+        subchannel_, nullptr, true /* inhibit_health_checking */);
   }
   json = grpc_json_create_child(nullptr, json, "state", nullptr,
                                 GRPC_JSON_OBJECT, false);

src/cpp/server/health/health.pb.c → src/core/ext/filters/client_channel/health/health.pb.c

@@ -1,8 +1,7 @@
 /* Automatically generated nanopb constant definitions */
 /* Generated by nanopb-0.3.7-dev */
 
-#include "src/cpp/server/health/health.pb.h"
-
+#include "src/core/ext/filters/client_channel/health/health.pb.h"
 /* @@protoc_insertion_point(includes) */
 #if PB_PROTO_HEADER_VERSION != 30
 #error Regenerate this file with the current version of nanopb generator.

src/cpp/server/health/health.pb.h → src/core/ext/filters/client_channel/health/health.pb.h

@@ -17,11 +17,12 @@ extern "C" {
 typedef enum _grpc_health_v1_HealthCheckResponse_ServingStatus {
     grpc_health_v1_HealthCheckResponse_ServingStatus_UNKNOWN = 0,
     grpc_health_v1_HealthCheckResponse_ServingStatus_SERVING = 1,
-    grpc_health_v1_HealthCheckResponse_ServingStatus_NOT_SERVING = 2
+    grpc_health_v1_HealthCheckResponse_ServingStatus_NOT_SERVING = 2,
+    grpc_health_v1_HealthCheckResponse_ServingStatus_SERVICE_UNKNOWN = 3
 } grpc_health_v1_HealthCheckResponse_ServingStatus;
 #define _grpc_health_v1_HealthCheckResponse_ServingStatus_MIN grpc_health_v1_HealthCheckResponse_ServingStatus_UNKNOWN
-#define _grpc_health_v1_HealthCheckResponse_ServingStatus_MAX grpc_health_v1_HealthCheckResponse_ServingStatus_NOT_SERVING
-#define _grpc_health_v1_HealthCheckResponse_ServingStatus_ARRAYSIZE ((grpc_health_v1_HealthCheckResponse_ServingStatus)(grpc_health_v1_HealthCheckResponse_ServingStatus_NOT_SERVING+1))
+#define _grpc_health_v1_HealthCheckResponse_ServingStatus_MAX grpc_health_v1_HealthCheckResponse_ServingStatus_SERVICE_UNKNOWN
+#define _grpc_health_v1_HealthCheckResponse_ServingStatus_ARRAYSIZE ((grpc_health_v1_HealthCheckResponse_ServingStatus)(grpc_health_v1_HealthCheckResponse_ServingStatus_SERVICE_UNKNOWN+1))
 
 /* Struct definitions */
 typedef struct _grpc_health_v1_HealthCheckRequest {

src/core/ext/filters/client_channel/health/health_check_client.cc

@@ -0,0 +1,653 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include <stdint.h>
+#include <stdio.h>
+
+#include "src/core/ext/filters/client_channel/health/health_check_client.h"
+
+#include "pb_decode.h"
+#include "pb_encode.h"
+#include "src/core/ext/filters/client_channel/health/health.pb.h"
+#include "src/core/lib/debug/trace.h"
+#include "src/core/lib/gprpp/mutex_lock.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/transport/error_utils.h"
+#include "src/core/lib/transport/status_metadata.h"
+
+#define HEALTH_CHECK_INITIAL_CONNECT_BACKOFF_SECONDS 1
+#define HEALTH_CHECK_RECONNECT_BACKOFF_MULTIPLIER 1.6
+#define HEALTH_CHECK_RECONNECT_MAX_BACKOFF_SECONDS 120
+#define HEALTH_CHECK_RECONNECT_JITTER 0.2
+
+grpc_core::TraceFlag grpc_health_check_client_trace(false,
+                                                    "health_check_client");
+
+namespace grpc_core {
+
+//
+// HealthCheckClient
+//
+
+HealthCheckClient::HealthCheckClient(
+    const char* service_name,
+    RefCountedPtr<ConnectedSubchannel> connected_subchannel,
+    grpc_pollset_set* interested_parties,
+    grpc_core::RefCountedPtr<grpc_core::channelz::SubchannelNode> channelz_node)
+    : InternallyRefCountedWithTracing<HealthCheckClient>(
+          &grpc_health_check_client_trace),
+      service_name_(service_name),
+      connected_subchannel_(std::move(connected_subchannel)),
+      interested_parties_(interested_parties),
+      channelz_node_(std::move(channelz_node)),
+      retry_backoff_(
+          BackOff::Options()
+              .set_initial_backoff(
+                  HEALTH_CHECK_INITIAL_CONNECT_BACKOFF_SECONDS * 1000)
+              .set_multiplier(HEALTH_CHECK_RECONNECT_BACKOFF_MULTIPLIER)
+              .set_jitter(HEALTH_CHECK_RECONNECT_JITTER)
+              .set_max_backoff(HEALTH_CHECK_RECONNECT_MAX_BACKOFF_SECONDS *
+                               1000)) {
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO, "created HealthCheckClient %p", this);
+  }
+  GRPC_CLOSURE_INIT(&retry_timer_callback_, OnRetryTimer, this,
+                    grpc_schedule_on_exec_ctx);
+  gpr_mu_init(&mu_);
+  StartCall();
+}
+
+HealthCheckClient::~HealthCheckClient() {
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO, "destroying HealthCheckClient %p", this);
+  }
+  GRPC_ERROR_UNREF(error_);
+  gpr_mu_destroy(&mu_);
+}
+
+void HealthCheckClient::NotifyOnHealthChange(grpc_connectivity_state* state,
+                                             grpc_closure* closure) {
+  MutexLock lock(&mu_);
+  GPR_ASSERT(notify_state_ == nullptr);
+  if (*state != state_) {
+    *state = state_;
+    GRPC_CLOSURE_SCHED(closure, GRPC_ERROR_REF(error_));
+    return;
+  }
+  notify_state_ = state;
+  on_health_changed_ = closure;
+}
+
+void HealthCheckClient::SetHealthStatus(grpc_connectivity_state state,
+                                        grpc_error* error) {
+  MutexLock lock(&mu_);
+  SetHealthStatusLocked(state, error);
+}
+
+void HealthCheckClient::SetHealthStatusLocked(grpc_connectivity_state state,
+                                              grpc_error* error) {
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO, "HealthCheckClient %p: setting state=%d error=%s", this,
+            state, grpc_error_string(error));
+  }
+  if (notify_state_ != nullptr && *notify_state_ != state) {
+    *notify_state_ = state;
+    notify_state_ = nullptr;
+    GRPC_CLOSURE_SCHED(on_health_changed_, GRPC_ERROR_REF(error));
+    on_health_changed_ = nullptr;
+  }
+  state_ = state;
+  GRPC_ERROR_UNREF(error_);
+  error_ = error;
+}
+
+void HealthCheckClient::Orphan() {
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO, "HealthCheckClient %p: shutting down", this);
+  }
+  {
+    MutexLock lock(&mu_);
+    if (on_health_changed_ != nullptr) {
+      *notify_state_ = GRPC_CHANNEL_SHUTDOWN;
+      notify_state_ = nullptr;
+      GRPC_CLOSURE_SCHED(on_health_changed_, GRPC_ERROR_NONE);
+      on_health_changed_ = nullptr;
+    }
+    shutting_down_ = true;
+    call_state_.reset();
+    if (retry_timer_callback_pending_) {
+      grpc_timer_cancel(&retry_timer_);
+    }
+  }
+  Unref(DEBUG_LOCATION, "orphan");
+}
+
+void HealthCheckClient::StartCall() {
+  MutexLock lock(&mu_);
+  StartCallLocked();
+}
+
+void HealthCheckClient::StartCallLocked() {
+  if (shutting_down_) return;
+  GPR_ASSERT(call_state_ == nullptr);
+  SetHealthStatusLocked(GRPC_CHANNEL_CONNECTING, GRPC_ERROR_NONE);
+  call_state_ = MakeOrphanable<CallState>(Ref(), interested_parties_);
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO, "HealthCheckClient %p: created CallState %p", this,
+            call_state_.get());
+  }
+  call_state_->StartCall();
+}
+
+void HealthCheckClient::StartRetryTimer() {
+  MutexLock lock(&mu_);
+  SetHealthStatusLocked(
+      GRPC_CHANNEL_TRANSIENT_FAILURE,
+      GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "health check call failed; will retry after backoff"));
+  grpc_millis next_try = retry_backoff_.NextAttemptTime();
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO, "HealthCheckClient %p: health check call lost...", this);
+    grpc_millis timeout = next_try - ExecCtx::Get()->Now();
+    if (timeout > 0) {
+      gpr_log(GPR_INFO,
+              "HealthCheckClient %p: ... will retry in %" PRId64 "ms.", this,
+              timeout);
+    } else {
+      gpr_log(GPR_INFO, "HealthCheckClient %p: ... retrying immediately.",
+              this);
+    }
+  }
+  // Ref for callback, tracked manually.
+  Ref(DEBUG_LOCATION, "health_retry_timer").release();
+  retry_timer_callback_pending_ = true;
+  grpc_timer_init(&retry_timer_, next_try, &retry_timer_callback_);
+}
+
+void HealthCheckClient::OnRetryTimer(void* arg, grpc_error* error) {
+  HealthCheckClient* self = static_cast<HealthCheckClient*>(arg);
+  {
+    MutexLock lock(&self->mu_);
+    self->retry_timer_callback_pending_ = false;
+    if (!self->shutting_down_ && error == GRPC_ERROR_NONE &&
+        self->call_state_ == nullptr) {
+      if (grpc_health_check_client_trace.enabled()) {
+        gpr_log(GPR_INFO, "HealthCheckClient %p: restarting health check call",
+                self);
+      }
+      self->StartCallLocked();
+    }
+  }
+  self->Unref(DEBUG_LOCATION, "health_retry_timer");
+}
+
+//
+// protobuf helpers
+//
+
+namespace {
+
+void EncodeRequest(const char* service_name,
+                   ManualConstructor<SliceBufferByteStream>* send_message) {
+  grpc_health_v1_HealthCheckRequest request_struct;
+  request_struct.has_service = true;
+  snprintf(request_struct.service, sizeof(request_struct.service), "%s",
+           service_name);
+  pb_ostream_t ostream;
+  memset(&ostream, 0, sizeof(ostream));
+  pb_encode(&ostream, grpc_health_v1_HealthCheckRequest_fields,
+            &request_struct);
+  grpc_slice request_slice = GRPC_SLICE_MALLOC(ostream.bytes_written);
+  ostream = pb_ostream_from_buffer(GRPC_SLICE_START_PTR(request_slice),
+                                   GRPC_SLICE_LENGTH(request_slice));
+  GPR_ASSERT(pb_encode(&ostream, grpc_health_v1_HealthCheckRequest_fields,
+                       &request_struct) != 0);
+  grpc_slice_buffer slice_buffer;
+  grpc_slice_buffer_init(&slice_buffer);
+  grpc_slice_buffer_add(&slice_buffer, request_slice);
+  send_message->Init(&slice_buffer, 0);
+  grpc_slice_buffer_destroy_internal(&slice_buffer);
+}
+
+// Returns true if healthy.
+// If there was an error parsing the response, sets *error and returns false.
+bool DecodeResponse(grpc_slice_buffer* slice_buffer, grpc_error** error) {
+  // If message is empty, assume unhealthy.
+  if (slice_buffer->length == 0) {
+    *error =
+        GRPC_ERROR_CREATE_FROM_STATIC_STRING("health check response was empty");
+    return false;
+  }
+  // Concatenate the slices to form a single string.
+  UniquePtr<uint8_t> recv_message_deleter;
+  uint8_t* recv_message;
+  if (slice_buffer->count == 1) {
+    recv_message = GRPC_SLICE_START_PTR(slice_buffer->slices[0]);
+  } else {
+    recv_message = static_cast<uint8_t*>(gpr_malloc(slice_buffer->length));
+    recv_message_deleter.reset(recv_message);
+    size_t offset = 0;
+    for (size_t i = 0; i < slice_buffer->count; ++i) {
+      memcpy(recv_message + offset,
+             GRPC_SLICE_START_PTR(slice_buffer->slices[i]),
+             GRPC_SLICE_LENGTH(slice_buffer->slices[i]));
+      offset += GRPC_SLICE_LENGTH(slice_buffer->slices[i]);
+    }
+  }
+  // Deserialize message.
+  grpc_health_v1_HealthCheckResponse response_struct;
+  pb_istream_t istream =
+      pb_istream_from_buffer(recv_message, slice_buffer->length);
+  if (!pb_decode(&istream, grpc_health_v1_HealthCheckResponse_fields,
+                 &response_struct)) {
+    // Can't parse message; assume unhealthy.
+    *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+        "cannot parse health check response");
+    return false;
+  }
+  if (!response_struct.has_status) {
+    // Field not present; assume unhealthy.
+    *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+        "status field not present in health check response");
+    return false;
+  }
+  return response_struct.status ==
+         grpc_health_v1_HealthCheckResponse_ServingStatus_SERVING;
+}
+
+}  // namespace
+
+//
+// HealthCheckClient::CallState
+//
+
+HealthCheckClient::CallState::CallState(
+    RefCountedPtr<HealthCheckClient> health_check_client,
+    grpc_pollset_set* interested_parties)
+    : InternallyRefCountedWithTracing<CallState>(
+          &grpc_health_check_client_trace),
+      health_check_client_(std::move(health_check_client)),
+      pollent_(grpc_polling_entity_create_from_pollset_set(interested_parties)),
+      arena_(gpr_arena_create(health_check_client_->connected_subchannel_
+                                  ->GetInitialCallSizeEstimate(0))) {
+  memset(&call_combiner_, 0, sizeof(call_combiner_));
+  grpc_call_combiner_init(&call_combiner_);
+  memset(context_, 0, sizeof(context_));
+  gpr_atm_rel_store(&seen_response_, static_cast<gpr_atm>(0));
+}
+
+HealthCheckClient::CallState::~CallState() {
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO, "HealthCheckClient %p: destroying CallState %p",
+            health_check_client_.get(), this);
+  }
+  if (call_ != nullptr) GRPC_SUBCHANNEL_CALL_UNREF(call_, "call_ended");
+  for (size_t i = 0; i < GRPC_CONTEXT_COUNT; i++) {
+    if (context_[i].destroy != nullptr) {
+      context_[i].destroy(context_[i].value);
+    }
+  }
+  // Unset the call combiner cancellation closure.  This has the
+  // effect of scheduling the previously set cancellation closure, if
+  // any, so that it can release any internal references it may be
+  // holding to the call stack. Also flush the closures on exec_ctx so that
+  // filters that schedule cancel notification closures on exec_ctx do not
+  // need to take a ref of the call stack to guarantee closure liveness.
+  grpc_call_combiner_set_notify_on_cancel(&call_combiner_, nullptr);
+  grpc_core::ExecCtx::Get()->Flush();
+  grpc_call_combiner_destroy(&call_combiner_);
+  gpr_arena_destroy(arena_);
+}
+
+void HealthCheckClient::CallState::Orphan() {
+  grpc_call_combiner_cancel(&call_combiner_, GRPC_ERROR_CANCELLED);
+  Cancel();
+}
+
+void HealthCheckClient::CallState::StartCall() {
+  ConnectedSubchannel::CallArgs args = {
+      &pollent_,
+      GRPC_MDSTR_SLASH_GRPC_DOT_HEALTH_DOT_V1_DOT_HEALTH_SLASH_WATCH,
+      gpr_now(GPR_CLOCK_MONOTONIC),  // start_time
+      GRPC_MILLIS_INF_FUTURE,        // deadline
+      arena_,
+      context_,
+      &call_combiner_,
+      0,  // parent_data_size
+  };
+  grpc_error* error =
+      health_check_client_->connected_subchannel_->CreateCall(args, &call_);
+  if (error != GRPC_ERROR_NONE) {
+    gpr_log(GPR_ERROR,
+            "HealthCheckClient %p CallState %p: error creating health "
+            "checking call on subchannel (%s); will retry",
+            health_check_client_.get(), this, grpc_error_string(error));
+    GRPC_ERROR_UNREF(error);
+    // Schedule instead of running directly, since we must not be
+    // holding health_check_client_->mu_ when CallEnded() is called.
+    Ref(DEBUG_LOCATION, "call_end_closure").release();
+    GRPC_CLOSURE_SCHED(
+        GRPC_CLOSURE_INIT(&batch_.handler_private.closure, CallEndedRetry, this,
+                          grpc_schedule_on_exec_ctx),
+        GRPC_ERROR_NONE);
+    return;
+  }
+  // Initialize payload and batch.
+  memset(&batch_, 0, sizeof(batch_));
+  payload_.context = context_;
+  batch_.payload = &payload_;
+  // on_complete callback takes ref, handled manually.
+  Ref(DEBUG_LOCATION, "on_complete").release();
+  batch_.on_complete = GRPC_CLOSURE_INIT(&on_complete_, OnComplete, this,
+                                         grpc_schedule_on_exec_ctx);
+  // Add send_initial_metadata op.
+  grpc_metadata_batch_init(&send_initial_metadata_);
+  error = grpc_metadata_batch_add_head(
+      &send_initial_metadata_, &path_metadata_storage_,
+      grpc_mdelem_from_slices(
+          GRPC_MDSTR_PATH,
+          GRPC_MDSTR_SLASH_GRPC_DOT_HEALTH_DOT_V1_DOT_HEALTH_SLASH_WATCH));
+  GPR_ASSERT(error == GRPC_ERROR_NONE);
+  payload_.send_initial_metadata.send_initial_metadata =
+      &send_initial_metadata_;
+  payload_.send_initial_metadata.send_initial_metadata_flags = 0;
+  payload_.send_initial_metadata.peer_string = nullptr;
+  batch_.send_initial_metadata = true;
+  // Add send_message op.
+  EncodeRequest(health_check_client_->service_name_, &send_message_);
+  payload_.send_message.send_message.reset(send_message_.get());
+  batch_.send_message = true;
+  // Add send_trailing_metadata op.
+  grpc_metadata_batch_init(&send_trailing_metadata_);
+  payload_.send_trailing_metadata.send_trailing_metadata =
+      &send_trailing_metadata_;
+  batch_.send_trailing_metadata = true;
+  // Add recv_initial_metadata op.
+  grpc_metadata_batch_init(&recv_initial_metadata_);
+  payload_.recv_initial_metadata.recv_initial_metadata =
+      &recv_initial_metadata_;
+  payload_.recv_initial_metadata.recv_flags = nullptr;
+  payload_.recv_initial_metadata.trailing_metadata_available = nullptr;
+  payload_.recv_initial_metadata.peer_string = nullptr;
+  // recv_initial_metadata_ready callback takes ref, handled manually.
+  Ref(DEBUG_LOCATION, "recv_initial_metadata_ready").release();
+  payload_.recv_initial_metadata.recv_initial_metadata_ready =
+      GRPC_CLOSURE_INIT(&recv_initial_metadata_ready_, RecvInitialMetadataReady,
+                        this, grpc_schedule_on_exec_ctx);
+  batch_.recv_initial_metadata = true;
+  // Add recv_message op.
+  payload_.recv_message.recv_message = &recv_message_;
+  // recv_message callback takes ref, handled manually.
+  Ref(DEBUG_LOCATION, "recv_message_ready").release();
+  payload_.recv_message.recv_message_ready = GRPC_CLOSURE_INIT(
+      &recv_message_ready_, RecvMessageReady, this, grpc_schedule_on_exec_ctx);
+  batch_.recv_message = true;
+  // Start batch.
+  StartBatch(&batch_);
+  // Initialize recv_trailing_metadata batch.
+  memset(&recv_trailing_metadata_batch_, 0,
+         sizeof(recv_trailing_metadata_batch_));
+  recv_trailing_metadata_batch_.payload = &payload_;
+  // Add recv_trailing_metadata op.
+  grpc_metadata_batch_init(&recv_trailing_metadata_);
+  payload_.recv_trailing_metadata.recv_trailing_metadata =
+      &recv_trailing_metadata_;
+  payload_.recv_trailing_metadata.collect_stats = &collect_stats_;
+  // This callback signals the end of the call, so it relies on the
+  // initial ref instead of taking a new ref.  When it's invoked, the
+  // initial ref is released.
+  payload_.recv_trailing_metadata.recv_trailing_metadata_ready =
+      GRPC_CLOSURE_INIT(&recv_trailing_metadata_ready_,
+                        RecvTrailingMetadataReady, this,
+                        grpc_schedule_on_exec_ctx);
+  recv_trailing_metadata_batch_.recv_trailing_metadata = true;
+  // Start recv_trailing_metadata batch.
+  StartBatch(&recv_trailing_metadata_batch_);
+}
+
+void HealthCheckClient::CallState::StartBatchInCallCombiner(void* arg,
+                                                            grpc_error* error) {
+  grpc_transport_stream_op_batch* batch =
+      static_cast<grpc_transport_stream_op_batch*>(arg);
+  grpc_subchannel_call* call =
+      static_cast<grpc_subchannel_call*>(batch->handler_private.extra_arg);
+  grpc_subchannel_call_process_op(call, batch);
+}
+
+void HealthCheckClient::CallState::StartBatch(
+    grpc_transport_stream_op_batch* batch) {
+  batch->handler_private.extra_arg = call_;
+  GRPC_CLOSURE_INIT(&batch->handler_private.closure, StartBatchInCallCombiner,
+                    batch, grpc_schedule_on_exec_ctx);
+  GRPC_CALL_COMBINER_START(&call_combiner_, &batch->handler_private.closure,
+                           GRPC_ERROR_NONE, "start_subchannel_batch");
+}
+
+void HealthCheckClient::CallState::OnCancelComplete(void* arg,
+                                                    grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  GRPC_CALL_COMBINER_STOP(&self->call_combiner_, "health_cancel");
+  self->Unref(DEBUG_LOCATION, "cancel");
+}
+
+void HealthCheckClient::CallState::StartCancel(void* arg, grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  auto* batch = grpc_make_transport_stream_op(
+      GRPC_CLOSURE_CREATE(OnCancelComplete, self, grpc_schedule_on_exec_ctx));
+  batch->cancel_stream = true;
+  batch->payload->cancel_stream.cancel_error = GRPC_ERROR_CANCELLED;
+  grpc_subchannel_call_process_op(self->call_, batch);
+}
+
+void HealthCheckClient::CallState::Cancel() {
+  if (call_ != nullptr) {
+    Ref(DEBUG_LOCATION, "cancel").release();
+    GRPC_CALL_COMBINER_START(
+        &call_combiner_,
+        GRPC_CLOSURE_CREATE(StartCancel, this, grpc_schedule_on_exec_ctx),
+        GRPC_ERROR_NONE, "health_cancel");
+  }
+}
+
+void HealthCheckClient::CallState::OnComplete(void* arg, grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  GRPC_CALL_COMBINER_STOP(&self->call_combiner_, "on_complete");
+  grpc_metadata_batch_destroy(&self->send_initial_metadata_);
+  grpc_metadata_batch_destroy(&self->send_trailing_metadata_);
+  self->Unref(DEBUG_LOCATION, "on_complete");
+}
+
+void HealthCheckClient::CallState::RecvInitialMetadataReady(void* arg,
+                                                            grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  GRPC_CALL_COMBINER_STOP(&self->call_combiner_, "recv_initial_metadata_ready");
+  grpc_metadata_batch_destroy(&self->recv_initial_metadata_);
+  self->Unref(DEBUG_LOCATION, "recv_initial_metadata_ready");
+}
+
+void HealthCheckClient::CallState::DoneReadingRecvMessage(grpc_error* error) {
+  recv_message_.reset();
+  if (error != GRPC_ERROR_NONE) {
+    GRPC_ERROR_UNREF(error);
+    Cancel();
+    grpc_slice_buffer_destroy_internal(&recv_message_buffer_);
+    Unref(DEBUG_LOCATION, "recv_message_ready");
+    return;
+  }
+  const bool healthy = DecodeResponse(&recv_message_buffer_, &error);
+  const grpc_connectivity_state state =
+      healthy ? GRPC_CHANNEL_READY : GRPC_CHANNEL_TRANSIENT_FAILURE;
+  if (error == GRPC_ERROR_NONE && !healthy) {
+    error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("backend unhealthy");
+  }
+  health_check_client_->SetHealthStatus(state, error);
+  gpr_atm_rel_store(&seen_response_, static_cast<gpr_atm>(1));
+  grpc_slice_buffer_destroy_internal(&recv_message_buffer_);
+  // Start another recv_message batch.
+  // This re-uses the ref we're holding.
+  // Note: Can't just reuse batch_ here, since we don't know that all
+  // callbacks from the original batch have completed yet.
+  memset(&recv_message_batch_, 0, sizeof(recv_message_batch_));
+  recv_message_batch_.payload = &payload_;
+  payload_.recv_message.recv_message = &recv_message_;
+  payload_.recv_message.recv_message_ready = GRPC_CLOSURE_INIT(
+      &recv_message_ready_, RecvMessageReady, this, grpc_schedule_on_exec_ctx);
+  recv_message_batch_.recv_message = true;
+  StartBatch(&recv_message_batch_);
+}
+
+grpc_error* HealthCheckClient::CallState::PullSliceFromRecvMessage() {
+  grpc_slice slice;
+  grpc_error* error = recv_message_->Pull(&slice);
+  if (error == GRPC_ERROR_NONE) {
+    grpc_slice_buffer_add(&recv_message_buffer_, slice);
+  }
+  return error;
+}
+
+void HealthCheckClient::CallState::ContinueReadingRecvMessage() {
+  while (recv_message_->Next(SIZE_MAX, &recv_message_ready_)) {
+    grpc_error* error = PullSliceFromRecvMessage();
+    if (error != GRPC_ERROR_NONE) {
+      DoneReadingRecvMessage(error);
+      return;
+    }
+    if (recv_message_buffer_.length == recv_message_->length()) {
+      DoneReadingRecvMessage(GRPC_ERROR_NONE);
+      break;
+    }
+  }
+}
+
+void HealthCheckClient::CallState::OnByteStreamNext(void* arg,
+                                                    grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  if (error != GRPC_ERROR_NONE) {
+    self->DoneReadingRecvMessage(GRPC_ERROR_REF(error));
+    return;
+  }
+  error = self->PullSliceFromRecvMessage();
+  if (error != GRPC_ERROR_NONE) {
+    self->DoneReadingRecvMessage(error);
+    return;
+  }
+  if (self->recv_message_buffer_.length == self->recv_message_->length()) {
+    self->DoneReadingRecvMessage(GRPC_ERROR_NONE);
+  } else {
+    self->ContinueReadingRecvMessage();
+  }
+}
+
+void HealthCheckClient::CallState::RecvMessageReady(void* arg,
+                                                    grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  GRPC_CALL_COMBINER_STOP(&self->call_combiner_, "recv_message_ready");
+  if (self->recv_message_ == nullptr) {
+    self->Unref(DEBUG_LOCATION, "recv_message_ready");
+    return;
+  }
+  grpc_slice_buffer_init(&self->recv_message_buffer_);
+  GRPC_CLOSURE_INIT(&self->recv_message_ready_, OnByteStreamNext, self,
+                    grpc_schedule_on_exec_ctx);
+  self->ContinueReadingRecvMessage();
+  // Ref will continue to be held until we finish draining the byte stream.
+}
+
+void HealthCheckClient::CallState::RecvTrailingMetadataReady(
+    void* arg, grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  GRPC_CALL_COMBINER_STOP(&self->call_combiner_,
+                          "recv_trailing_metadata_ready");
+  // Get call status.
+  grpc_status_code status = GRPC_STATUS_UNKNOWN;
+  if (error != GRPC_ERROR_NONE) {
+    grpc_error_get_status(error, GRPC_MILLIS_INF_FUTURE, &status,
+                          nullptr /* slice */, nullptr /* http_error */,
+                          nullptr /* error_string */);
+  } else if (self->recv_trailing_metadata_.idx.named.grpc_status != nullptr) {
+    status = grpc_get_status_code_from_metadata(
+        self->recv_trailing_metadata_.idx.named.grpc_status->md);
+  }
+  if (grpc_health_check_client_trace.enabled()) {
+    gpr_log(GPR_INFO,
+            "HealthCheckClient %p CallState %p: health watch failed with "
+            "status %d",
+            self->health_check_client_.get(), self, status);
+  }
+  // Clean up.
+  grpc_metadata_batch_destroy(&self->recv_trailing_metadata_);
+  // For status UNIMPLEMENTED, give up and assume always healthy.
+  bool retry = true;
+  if (status == GRPC_STATUS_UNIMPLEMENTED) {
+    static const char kErrorMessage[] =
+        "health checking Watch method returned UNIMPLEMENTED; "
+        "disabling health checks but assuming server is healthy";
+    gpr_log(GPR_ERROR, kErrorMessage);
+    if (self->health_check_client_->channelz_node_ != nullptr) {
+      self->health_check_client_->channelz_node_->AddTraceEvent(
+          channelz::ChannelTrace::Error,
+          grpc_slice_from_static_string(kErrorMessage));
+    }
+    self->health_check_client_->SetHealthStatus(GRPC_CHANNEL_READY,
+                                                GRPC_ERROR_NONE);
+    retry = false;
+  }
+  self->CallEnded(retry);
+}
+
+void HealthCheckClient::CallState::CallEndedRetry(void* arg,
+                                                  grpc_error* error) {
+  HealthCheckClient::CallState* self =
+      static_cast<HealthCheckClient::CallState*>(arg);
+  self->CallEnded(true /* retry */);
+  self->Unref(DEBUG_LOCATION, "call_end_closure");
+}
+
+void HealthCheckClient::CallState::CallEnded(bool retry) {
+  // If this CallState is still in use, this call ended because of a failure,
+  // so we need to stop using it and optionally create a new one.
+  // Otherwise, we have deliberately ended this call, and no further action
+  // is required.
+  if (this == health_check_client_->call_state_.get()) {
+    health_check_client_->call_state_.reset();
+    if (retry) {
+      GPR_ASSERT(!health_check_client_->shutting_down_);
+      if (static_cast<bool>(gpr_atm_acq_load(&seen_response_))) {
+        // If the call fails after we've gotten a successful response, reset
+        // the backoff and restart the call immediately.
+        health_check_client_->retry_backoff_.Reset();
+        health_check_client_->StartCall();
+      } else {
+        // If the call failed without receiving any messages, retry later.
+        health_check_client_->StartRetryTimer();
+      }
+    }
+  }
+  Unref(DEBUG_LOCATION, "call_ended");
+}
+
+}  // namespace grpc_core

src/core/ext/filters/client_channel/health/health_check_client.h

@@ -0,0 +1,173 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HEALTH_HEALTH_CHECK_CLIENT_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HEALTH_HEALTH_CHECK_CLIENT_H
+
+#include <grpc/support/port_platform.h>
+
+#include <grpc/grpc.h>
+#include <grpc/support/atm.h>
+#include <grpc/support/sync.h>
+
+#include "src/core/ext/filters/client_channel/client_channel_channelz.h"
+#include "src/core/ext/filters/client_channel/subchannel.h"
+#include "src/core/lib/backoff/backoff.h"
+#include "src/core/lib/gpr/arena.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/call_combiner.h"
+#include "src/core/lib/iomgr/closure.h"
+#include "src/core/lib/iomgr/polling_entity.h"
+#include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/transport/byte_stream.h"
+#include "src/core/lib/transport/metadata_batch.h"
+#include "src/core/lib/transport/transport.h"
+
+namespace grpc_core {
+
+class HealthCheckClient
+    : public InternallyRefCountedWithTracing<HealthCheckClient> {
+ public:
+  HealthCheckClient(const char* service_name,
+                    RefCountedPtr<ConnectedSubchannel> connected_subchannel,
+                    grpc_pollset_set* interested_parties,
+                    RefCountedPtr<channelz::SubchannelNode> channelz_node);
+
+  ~HealthCheckClient();
+
+  // When the health state changes from *state, sets *state to the new
+  // value and schedules closure.
+  // Only one closure can be outstanding at a time.
+  void NotifyOnHealthChange(grpc_connectivity_state* state,
+                            grpc_closure* closure);
+
+  void Orphan() override;
+
+ private:
+  // Contains a call to the backend and all the data related to the call.
+  class CallState : public InternallyRefCountedWithTracing<CallState> {
+   public:
+    CallState(RefCountedPtr<HealthCheckClient> health_check_client,
+              grpc_pollset_set* interested_parties_);
+    ~CallState();
+
+    void Orphan() override;
+
+    void StartCall();
+
+   private:
+    void Cancel();
+
+    void StartBatch(grpc_transport_stream_op_batch* batch);
+    static void StartBatchInCallCombiner(void* arg, grpc_error* error);
+
+    static void CallEndedRetry(void* arg, grpc_error* error);
+    void CallEnded(bool retry);
+
+    static void OnComplete(void* arg, grpc_error* error);
+    static void RecvInitialMetadataReady(void* arg, grpc_error* error);
+    static void RecvMessageReady(void* arg, grpc_error* error);
+    static void RecvTrailingMetadataReady(void* arg, grpc_error* error);
+    static void StartCancel(void* arg, grpc_error* error);
+    static void OnCancelComplete(void* arg, grpc_error* error);
+
+    static void OnByteStreamNext(void* arg, grpc_error* error);
+    void ContinueReadingRecvMessage();
+    grpc_error* PullSliceFromRecvMessage();
+    void DoneReadingRecvMessage(grpc_error* error);
+
+    RefCountedPtr<HealthCheckClient> health_check_client_;
+    grpc_polling_entity pollent_;
+
+    gpr_arena* arena_;
+    grpc_call_combiner call_combiner_;
+    grpc_call_context_element context_[GRPC_CONTEXT_COUNT];
+
+    // The streaming call to the backend. Always non-NULL.
+    grpc_subchannel_call* call_;
+
+    grpc_transport_stream_op_batch_payload payload_;
+    grpc_transport_stream_op_batch batch_;
+    grpc_transport_stream_op_batch recv_message_batch_;
+    grpc_transport_stream_op_batch recv_trailing_metadata_batch_;
+
+    grpc_closure on_complete_;
+
+    // send_initial_metadata
+    grpc_metadata_batch send_initial_metadata_;
+    grpc_linked_mdelem path_metadata_storage_;
+
+    // send_message
+    ManualConstructor<SliceBufferByteStream> send_message_;
+
+    // send_trailing_metadata
+    grpc_metadata_batch send_trailing_metadata_;
+
+    // recv_initial_metadata
+    grpc_metadata_batch recv_initial_metadata_;
+    grpc_closure recv_initial_metadata_ready_;
+
+    // recv_message
+    OrphanablePtr<ByteStream> recv_message_;
+    grpc_closure recv_message_ready_;
+    grpc_slice_buffer recv_message_buffer_;
+    gpr_atm seen_response_;
+
+    // recv_trailing_metadata
+    grpc_metadata_batch recv_trailing_metadata_;
+    grpc_transport_stream_stats collect_stats_;
+    grpc_closure recv_trailing_metadata_ready_;
+  };
+
+  void StartCall();
+  void StartCallLocked();  // Requires holding mu_.
+
+  void StartRetryTimer();
+  static void OnRetryTimer(void* arg, grpc_error* error);
+
+  void SetHealthStatus(grpc_connectivity_state state, grpc_error* error);
+  void SetHealthStatusLocked(grpc_connectivity_state state,
+                             grpc_error* error);  // Requires holding mu_.
+
+  const char* service_name_;  // Do not own.
+  RefCountedPtr<ConnectedSubchannel> connected_subchannel_;
+  grpc_pollset_set* interested_parties_;  // Do not own.
+  RefCountedPtr<channelz::SubchannelNode> channelz_node_;
+
+  gpr_mu mu_;
+  grpc_connectivity_state state_ = GRPC_CHANNEL_CONNECTING;
+  grpc_error* error_ = GRPC_ERROR_NONE;
+  grpc_connectivity_state* notify_state_ = nullptr;
+  grpc_closure* on_health_changed_ = nullptr;
+  bool shutting_down_ = false;
+
+  // The data associated with the current health check call.  It holds a ref
+  // to this HealthCheckClient object.
+  OrphanablePtr<CallState> call_state_;
+
+  // Call retry state.
+  BackOff retry_backoff_;
+  grpc_timer retry_timer_;
+  grpc_closure retry_timer_callback_;
+  bool retry_timer_callback_pending_ = false;
+};
+
+}  // namespace grpc_core
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HEALTH_HEALTH_CHECK_CLIENT_H */

src/core/ext/filters/client_channel/http_connect_handshaker.cc

@@ -29,7 +29,6 @@
 
 #include "src/core/ext/filters/client_channel/client_channel.h"
 #include "src/core/ext/filters/client_channel/resolver_registry.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/gpr/env.h"
@@ -37,6 +36,7 @@
 #include "src/core/lib/http/format_request.h"
 #include "src/core/lib/http/parser.h"
 #include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 typedef struct http_connect_handshaker {
   // Base class.  Must be first.

src/core/ext/filters/client_channel/http_proxy.cc

@@ -29,12 +29,12 @@
 
 #include "src/core/ext/filters/client_channel/http_connect_handshaker.h"
 #include "src/core/ext/filters/client_channel/proxy_mapper_registry.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/gpr/env.h"
 #include "src/core/lib/gpr/host_port.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/slice/b64.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 /**
  * Parses the 'https_proxy' env var (fallback on 'http_proxy') and returns the

src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc

@@ -1699,7 +1699,7 @@ grpc_channel_args* GrpcLb::CreateRoundRobinPolicyArgsLocked() {
   // Replace the LB addresses in the channel args that we pass down to
   // the subchannel.
   static const char* keys_to_remove[] = {GRPC_ARG_LB_ADDRESSES};
-  const grpc_arg args_to_add[] = {
+  grpc_arg args_to_add[3] = {
       grpc_lb_addresses_create_channel_arg(addresses),
       // A channel arg indicating if the target is a backend inferred from a
       // grpclb load balancer.
@@ -1708,9 +1708,15 @@ grpc_channel_args* GrpcLb::CreateRoundRobinPolicyArgsLocked() {
               GRPC_ARG_ADDRESS_IS_BACKEND_FROM_GRPCLB_LOAD_BALANCER),
           is_backend_from_grpclb_load_balancer),
   };
+  size_t num_args_to_add = 2;
+  if (is_backend_from_grpclb_load_balancer) {
+    args_to_add[2] = grpc_channel_arg_integer_create(
+        const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1);
+    ++num_args_to_add;
+  }
   grpc_channel_args* args = grpc_channel_args_copy_and_add_and_remove(
       args_, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove), args_to_add,
-      GPR_ARRAY_SIZE(args_to_add));
+      num_args_to_add);
   grpc_lb_addresses_destroy(addresses);
   return args;
 }

src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc

@@ -359,9 +359,14 @@ void PickFirst::UpdateLocked(const grpc_channel_args& args) {
             "Pick First %p received update with %" PRIuPTR " addresses", this,
             addresses->num_addresses);
   }
+  grpc_arg new_arg = grpc_channel_arg_integer_create(
+      const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1);
+  grpc_channel_args* new_args =
+      grpc_channel_args_copy_and_add(&args, &new_arg, 1);
   auto subchannel_list = MakeOrphanable<PickFirstSubchannelList>(
       this, &grpc_lb_pick_first_trace, addresses, combiner(),
-      client_channel_factory(), args);
+      client_channel_factory(), *new_args);
+  grpc_channel_args_destroy(new_args);
   if (subchannel_list->num_subchannels() == 0) {
     // Empty update or no valid subchannels. Unsubscribe from all current
     // subchannels and put the channel in TRANSIENT_FAILURE.

src/core/ext/filters/client_channel/lb_policy/subchannel_list.h

@@ -102,8 +102,8 @@ class SubchannelData {
   // ProcessConnectivityChangeLocked()).
   grpc_connectivity_state CheckConnectivityStateLocked(grpc_error** error) {
     GPR_ASSERT(!connectivity_notification_pending_);
-    pending_connectivity_state_unsafe_ =
-        grpc_subchannel_check_connectivity(subchannel(), error);
+    pending_connectivity_state_unsafe_ = grpc_subchannel_check_connectivity(
+        subchannel(), error, subchannel_list_->inhibit_health_checking());
     UpdateConnectedSubchannelLocked();
     return pending_connectivity_state_unsafe_;
   }
@@ -216,6 +216,7 @@ class SubchannelList
   // Accessors.
   LoadBalancingPolicy* policy() const { return policy_; }
   TraceFlag* tracer() const { return tracer_; }
+  bool inhibit_health_checking() const { return inhibit_health_checking_; }
 
   // Resets connection backoff of all subchannels.
   // TODO(roth): We will probably need to rethink this as part of moving
@@ -254,6 +255,8 @@ class SubchannelList
 
   TraceFlag* tracer_;
 
+  bool inhibit_health_checking_;
+
   grpc_combiner* combiner_;
 
   // The list of subchannels.
@@ -340,7 +343,8 @@ void SubchannelData<SubchannelListType,
   subchannel_list()->Ref(DEBUG_LOCATION, "connectivity_watch").release();
   grpc_subchannel_notify_on_state_change(
       subchannel_, subchannel_list_->policy()->interested_parties(),
-      &pending_connectivity_state_unsafe_, &connectivity_changed_closure_);
+      &pending_connectivity_state_unsafe_, &connectivity_changed_closure_,
+      subchannel_list_->inhibit_health_checking());
 }
 
 template <typename SubchannelListType, typename SubchannelDataType>
@@ -359,7 +363,8 @@ void SubchannelData<SubchannelListType,
   GPR_ASSERT(connectivity_notification_pending_);
   grpc_subchannel_notify_on_state_change(
       subchannel_, subchannel_list_->policy()->interested_parties(),
-      &pending_connectivity_state_unsafe_, &connectivity_changed_closure_);
+      &pending_connectivity_state_unsafe_, &connectivity_changed_closure_,
+      subchannel_list_->inhibit_health_checking());
 }
 
 template <typename SubchannelListType, typename SubchannelDataType>
@@ -390,8 +395,9 @@ void SubchannelData<SubchannelListType, SubchannelDataType>::
             subchannel_, reason);
   }
   GPR_ASSERT(connectivity_notification_pending_);
-  grpc_subchannel_notify_on_state_change(subchannel_, nullptr, nullptr,
-                                         &connectivity_changed_closure_);
+  grpc_subchannel_notify_on_state_change(
+      subchannel_, nullptr, nullptr, &connectivity_changed_closure_,
+      subchannel_list_->inhibit_health_checking());
 }
 
 template <typename SubchannelListType, typename SubchannelDataType>
@@ -499,8 +505,13 @@ SubchannelList<SubchannelListType, SubchannelDataType>::SubchannelList(
   subchannels_.reserve(addresses->num_addresses);
   // We need to remove the LB addresses in order to be able to compare the
   // subchannel keys of subchannels from a different batch of addresses.
+  // We also remove the inhibit-health-checking arg, since we are
+  // handling that here.
+  inhibit_health_checking_ = grpc_channel_arg_get_bool(
+      grpc_channel_args_find(&args, GRPC_ARG_INHIBIT_HEALTH_CHECKING), false);
   static const char* keys_to_remove[] = {GRPC_ARG_SUBCHANNEL_ADDRESS,
-                                         GRPC_ARG_LB_ADDRESSES};
+                                         GRPC_ARG_LB_ADDRESSES,
+                                         GRPC_ARG_INHIBIT_HEALTH_CHECKING};
   // Create a subchannel for each address.
   grpc_subchannel_args sc_args;
   for (size_t i = 0; i < addresses->num_addresses; i++) {

src/core/ext/filters/client_channel/lb_policy/xds/xds.cc

@@ -0,0 +1,1869 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/// Implementation of the gRPC LB policy.
+///
+/// This policy takes as input a list of resolved addresses, which must
+/// include at least one balancer address.
+///
+/// An internal channel (\a lb_channel_) is created for the addresses
+/// from that are balancers.  This channel behaves just like a regular
+/// channel that uses pick_first to select from the list of balancer
+/// addresses.
+///
+/// The first time the policy gets a request for a pick, a ping, or to exit
+/// the idle state, \a StartPickingLocked() is called. This method is
+/// responsible for instantiating the internal *streaming* call to the LB
+/// server (whichever address pick_first chose).  The call will be complete
+/// when either the balancer sends status or when we cancel the call (e.g.,
+/// because we are shutting down).  In needed, we retry the call.  If we
+/// received at least one valid message from the server, a new call attempt
+/// will be made immediately; otherwise, we apply back-off delays between
+/// attempts.
+///
+/// We maintain an internal round_robin policy instance for distributing
+/// requests across backends.  Whenever we receive a new serverlist from
+/// the balancer, we update the round_robin policy with the new list of
+/// addresses.  If we cannot communicate with the balancer on startup,
+/// however, we may enter fallback mode, in which case we will populate
+/// the RR policy's addresses from the backend addresses returned by the
+/// resolver.
+///
+/// Once an RR policy instance is in place (and getting updated as described),
+/// calls for a pick, a ping, or a cancellation will be serviced right
+/// away by forwarding them to the RR instance.  Any time there's no RR
+/// policy available (i.e., right after the creation of the gRPCLB policy),
+/// pick and ping requests are added to a list of pending picks and pings
+/// to be flushed and serviced when the RR policy instance becomes available.
+///
+/// \see https://github.com/grpc/grpc/blob/master/doc/load-balancing.md for the
+/// high level design and details.
+
+// With the addition of a libuv endpoint, sockaddr.h now includes uv.h when
+// using that endpoint. Because of various transitive includes in uv.h,
+// including windows.h on Windows, uv.h must be included before other system
+// headers. Therefore, sockaddr.h must always be included first.
+#include <grpc/support/port_platform.h>
+
+#include "src/core/lib/iomgr/sockaddr.h"
+#include "src/core/lib/iomgr/socket_utils.h"
+
+#include <inttypes.h>
+#include <limits.h>
+#include <string.h>
+
+#include <grpc/byte_buffer_reader.h>
+#include <grpc/grpc.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/time.h>
+
+#include "src/core/ext/filters/client_channel/client_channel.h"
+#include "src/core/ext/filters/client_channel/client_channel_factory.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h"
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/ext/filters/client_channel/parse_address.h"
+#include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
+#include "src/core/ext/filters/client_channel/subchannel_index.h"
+#include "src/core/lib/backoff/backoff.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/gpr/host_port.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/gprpp/mutex_lock.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/combiner.h"
+#include "src/core/lib/iomgr/sockaddr.h"
+#include "src/core/lib/iomgr/sockaddr_utils.h"
+#include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/slice/slice_hash_table.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/slice/slice_string_helpers.h"
+#include "src/core/lib/surface/call.h"
+#include "src/core/lib/surface/channel.h"
+#include "src/core/lib/surface/channel_init.h"
+#include "src/core/lib/transport/static_metadata.h"
+
+#define GRPC_XDS_INITIAL_CONNECT_BACKOFF_SECONDS 1
+#define GRPC_XDS_RECONNECT_BACKOFF_MULTIPLIER 1.6
+#define GRPC_XDS_RECONNECT_MAX_BACKOFF_SECONDS 120
+#define GRPC_XDS_RECONNECT_JITTER 0.2
+#define GRPC_XDS_DEFAULT_FALLBACK_TIMEOUT_MS 10000
+
+namespace grpc_core {
+
+TraceFlag grpc_lb_xds_trace(false, "xds");
+
+namespace {
+
+class XdsLb : public LoadBalancingPolicy {
+ public:
+  XdsLb(const grpc_lb_addresses* addresses, const Args& args);
+
+  void UpdateLocked(const grpc_channel_args& args) override;
+  bool PickLocked(PickState* pick, grpc_error** error) override;
+  void CancelPickLocked(PickState* pick, grpc_error* error) override;
+  void CancelMatchingPicksLocked(uint32_t initial_metadata_flags_mask,
+                                 uint32_t initial_metadata_flags_eq,
+                                 grpc_error* error) override;
+  void NotifyOnStateChangeLocked(grpc_connectivity_state* state,
+                                 grpc_closure* closure) override;
+  grpc_connectivity_state CheckConnectivityLocked(
+      grpc_error** connectivity_error) override;
+  void HandOffPendingPicksLocked(LoadBalancingPolicy* new_policy) override;
+  void ExitIdleLocked() override;
+  void ResetBackoffLocked() override;
+  void FillChildRefsForChannelz(
+      channelz::ChildRefsList* child_subchannels,
+      channelz::ChildRefsList* child_channels) override;
+
+ private:
+  /// Linked list of pending pick requests. It stores all information needed to
+  /// eventually call (Round Robin's) pick() on them. They mainly stay pending
+  /// waiting for the RR policy to be created.
+  ///
+  /// Note that when a pick is sent to the RR policy, we inject our own
+  /// on_complete callback, so that we can intercept the result before
+  /// invoking the original on_complete callback.  This allows us to set the
+  /// LB token metadata and add client_stats to the call context.
+  /// See \a pending_pick_complete() for details.
+  struct PendingPick {
+    // The xds lb instance that created the wrapping. This instance is not
+    // owned; reference counts are untouched. It's used only for logging
+    // purposes.
+    XdsLb* xdslb_policy;
+    // The original pick.
+    PickState* pick;
+    // Our on_complete closure and the original one.
+    grpc_closure on_complete;
+    grpc_closure* original_on_complete;
+    // The LB token associated with the pick.  This is set via user_data in
+    // the pick.
+    grpc_mdelem lb_token;
+    // Stats for client-side load reporting.
+    RefCountedPtr<XdsLbClientStats> client_stats;
+    // Next pending pick.
+    PendingPick* next = nullptr;
+  };
+
+  /// Contains a call to the LB server and all the data related to the call.
+  class BalancerCallState
+      : public InternallyRefCountedWithTracing<BalancerCallState> {
+   public:
+    explicit BalancerCallState(
+        RefCountedPtr<LoadBalancingPolicy> parent_xdslb_policy);
+
+    // It's the caller's responsibility to ensure that Orphan() is called from
+    // inside the combiner.
+    void Orphan() override;
+
+    void StartQuery();
+
+    XdsLbClientStats* client_stats() const { return client_stats_.get(); }
+
+    bool seen_initial_response() const { return seen_initial_response_; }
+
+   private:
+    // So Delete() can access our private dtor.
+    template <typename T>
+    friend void grpc_core::Delete(T*);
+
+    ~BalancerCallState();
+
+    XdsLb* xdslb_policy() const {
+      return static_cast<XdsLb*>(xdslb_policy_.get());
+    }
+
+    void ScheduleNextClientLoadReportLocked();
+    void SendClientLoadReportLocked();
+
+    static bool LoadReportCountersAreZero(xds_grpclb_request* request);
+
+    static void MaybeSendClientLoadReportLocked(void* arg, grpc_error* error);
+    static void ClientLoadReportDoneLocked(void* arg, grpc_error* error);
+    static void OnInitialRequestSentLocked(void* arg, grpc_error* error);
+    static void OnBalancerMessageReceivedLocked(void* arg, grpc_error* error);
+    static void OnBalancerStatusReceivedLocked(void* arg, grpc_error* error);
+
+    // The owning LB policy.
+    RefCountedPtr<LoadBalancingPolicy> xdslb_policy_;
+
+    // The streaming call to the LB server. Always non-NULL.
+    grpc_call* lb_call_ = nullptr;
+
+    // recv_initial_metadata
+    grpc_metadata_array lb_initial_metadata_recv_;
+
+    // send_message
+    grpc_byte_buffer* send_message_payload_ = nullptr;
+    grpc_closure lb_on_initial_request_sent_;
+
+    // recv_message
+    grpc_byte_buffer* recv_message_payload_ = nullptr;
+    grpc_closure lb_on_balancer_message_received_;
+    bool seen_initial_response_ = false;
+
+    // recv_trailing_metadata
+    grpc_closure lb_on_balancer_status_received_;
+    grpc_metadata_array lb_trailing_metadata_recv_;
+    grpc_status_code lb_call_status_;
+    grpc_slice lb_call_status_details_;
+
+    // The stats for client-side load reporting associated with this LB call.
+    // Created after the first serverlist is received.
+    RefCountedPtr<XdsLbClientStats> client_stats_;
+    grpc_millis client_stats_report_interval_ = 0;
+    grpc_timer client_load_report_timer_;
+    bool client_load_report_timer_callback_pending_ = false;
+    bool last_client_load_report_counters_were_zero_ = false;
+    bool client_load_report_is_due_ = false;
+    // The closure used for either the load report timer or the callback for
+    // completion of sending the load report.
+    grpc_closure client_load_report_closure_;
+  };
+
+  ~XdsLb();
+
+  void ShutdownLocked() override;
+
+  // Helper function used in ctor and UpdateLocked().
+  void ProcessChannelArgsLocked(const grpc_channel_args& args);
+
+  // Methods for dealing with the balancer channel and call.
+  void StartPickingLocked();
+  void StartBalancerCallLocked();
+  static void OnFallbackTimerLocked(void* arg, grpc_error* error);
+  void StartBalancerCallRetryTimerLocked();
+  static void OnBalancerCallRetryTimerLocked(void* arg, grpc_error* error);
+  static void OnBalancerChannelConnectivityChangedLocked(void* arg,
+                                                         grpc_error* error);
+
+  // Pending pick methods.
+  static void PendingPickSetMetadataAndContext(PendingPick* pp);
+  PendingPick* PendingPickCreate(PickState* pick);
+  void AddPendingPick(PendingPick* pp);
+  static void OnPendingPickComplete(void* arg, grpc_error* error);
+
+  // Methods for dealing with the RR policy.
+  void CreateOrUpdateRoundRobinPolicyLocked();
+  grpc_channel_args* CreateRoundRobinPolicyArgsLocked();
+  void CreateRoundRobinPolicyLocked(const Args& args);
+  bool PickFromRoundRobinPolicyLocked(bool force_async, PendingPick* pp,
+                                      grpc_error** error);
+  void UpdateConnectivityStateFromRoundRobinPolicyLocked(
+      grpc_error* rr_state_error);
+  static void OnRoundRobinConnectivityChangedLocked(void* arg,
+                                                    grpc_error* error);
+  static void OnRoundRobinRequestReresolutionLocked(void* arg,
+                                                    grpc_error* error);
+
+  // Who the client is trying to communicate with.
+  const char* server_name_ = nullptr;
+
+  // Current channel args from the resolver.
+  grpc_channel_args* args_ = nullptr;
+
+  // Internal state.
+  bool started_picking_ = false;
+  bool shutting_down_ = false;
+  grpc_connectivity_state_tracker state_tracker_;
+
+  // The channel for communicating with the LB server.
+  grpc_channel* lb_channel_ = nullptr;
+  // Mutex to protect the channel to the LB server. This is used when
+  // processing a channelz request.
+  gpr_mu lb_channel_mu_;
+  grpc_connectivity_state lb_channel_connectivity_;
+  grpc_closure lb_channel_on_connectivity_changed_;
+  // Are we already watching the LB channel's connectivity?
+  bool watching_lb_channel_ = false;
+  // Response generator to inject address updates into lb_channel_.
+  RefCountedPtr<FakeResolverResponseGenerator> response_generator_;
+
+  // The data associated with the current LB call. It holds a ref to this LB
+  // policy. It's initialized every time we query for backends. It's reset to
+  // NULL whenever the current LB call is no longer needed (e.g., the LB policy
+  // is shutting down, or the LB call has ended). A non-NULL lb_calld_ always
+  // contains a non-NULL lb_call_.
+  OrphanablePtr<BalancerCallState> lb_calld_;
+  // Timeout in milliseconds for the LB call. 0 means no deadline.
+  int lb_call_timeout_ms_ = 0;
+  // Balancer call retry state.
+  BackOff lb_call_backoff_;
+  bool retry_timer_callback_pending_ = false;
+  grpc_timer lb_call_retry_timer_;
+  grpc_closure lb_on_call_retry_;
+
+  // The deserialized response from the balancer. May be nullptr until one
+  // such response has arrived.
+  xds_grpclb_serverlist* serverlist_ = nullptr;
+  // Index into serverlist for next pick.
+  // If the server at this index is a drop, we return a drop.
+  // Otherwise, we delegate to the RR policy.
+  size_t serverlist_index_ = 0;
+
+  // Timeout in milliseconds for before using fallback backend addresses.
+  // 0 means not using fallback.
+  int lb_fallback_timeout_ms_ = 0;
+  // The backend addresses from the resolver.
+  grpc_lb_addresses* fallback_backend_addresses_ = nullptr;
+  // Fallback timer.
+  bool fallback_timer_callback_pending_ = false;
+  grpc_timer lb_fallback_timer_;
+  grpc_closure lb_on_fallback_;
+
+  // Pending picks that are waiting on the RR policy's connectivity.
+  PendingPick* pending_picks_ = nullptr;
+
+  // The RR policy to use for the backends.
+  OrphanablePtr<LoadBalancingPolicy> rr_policy_;
+  grpc_connectivity_state rr_connectivity_state_;
+  grpc_closure on_rr_connectivity_changed_;
+  grpc_closure on_rr_request_reresolution_;
+};
+
+//
+// serverlist parsing code
+//
+
+// vtable for LB tokens in grpc_lb_addresses
+void* lb_token_copy(void* token) {
+  return token == nullptr
+             ? nullptr
+             : (void*)GRPC_MDELEM_REF(grpc_mdelem{(uintptr_t)token}).payload;
+}
+void lb_token_destroy(void* token) {
+  if (token != nullptr) {
+    GRPC_MDELEM_UNREF(grpc_mdelem{(uintptr_t)token});
+  }
+}
+int lb_token_cmp(void* token1, void* token2) {
+  if (token1 > token2) return 1;
+  if (token1 < token2) return -1;
+  return 0;
+}
+const grpc_lb_user_data_vtable lb_token_vtable = {
+    lb_token_copy, lb_token_destroy, lb_token_cmp};
+
+// Returns the backend addresses extracted from the given addresses.
+grpc_lb_addresses* ExtractBackendAddresses(const grpc_lb_addresses* addresses) {
+  // First pass: count the number of backend addresses.
+  size_t num_backends = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (!addresses->addresses[i].is_balancer) {
+      ++num_backends;
+    }
+  }
+  // Second pass: actually populate the addresses and (empty) LB tokens.
+  grpc_lb_addresses* backend_addresses =
+      grpc_lb_addresses_create(num_backends, &lb_token_vtable);
+  size_t num_copied = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (addresses->addresses[i].is_balancer) continue;
+    const grpc_resolved_address* addr = &addresses->addresses[i].address;
+    grpc_lb_addresses_set_address(backend_addresses, num_copied, &addr->addr,
+                                  addr->len, false /* is_balancer */,
+                                  nullptr /* balancer_name */,
+                                  (void*)GRPC_MDELEM_LB_TOKEN_EMPTY.payload);
+    ++num_copied;
+  }
+  return backend_addresses;
+}
+
+bool IsServerValid(const xds_grpclb_server* server, size_t idx, bool log) {
+  if (server->drop) return false;
+  const xds_grpclb_ip_address* ip = &server->ip_address;
+  if (GPR_UNLIKELY(server->port >> 16 != 0)) {
+    if (log) {
+      gpr_log(GPR_ERROR,
+              "Invalid port '%d' at index %lu of serverlist. Ignoring.",
+              server->port, (unsigned long)idx);
+    }
+    return false;
+  }
+  if (GPR_UNLIKELY(ip->size != 4 && ip->size != 16)) {
+    if (log) {
+      gpr_log(GPR_ERROR,
+              "Expected IP to be 4 or 16 bytes, got %d at index %lu of "
+              "serverlist. Ignoring",
+              ip->size, (unsigned long)idx);
+    }
+    return false;
+  }
+  return true;
+}
+
+void ParseServer(const xds_grpclb_server* server, grpc_resolved_address* addr) {
+  memset(addr, 0, sizeof(*addr));
+  if (server->drop) return;
+  const uint16_t netorder_port = grpc_htons((uint16_t)server->port);
+  /* the addresses are given in binary format (a in(6)_addr struct) in
+   * server->ip_address.bytes. */
+  const xds_grpclb_ip_address* ip = &server->ip_address;
+  if (ip->size == 4) {
+    addr->len = static_cast<socklen_t>(sizeof(grpc_sockaddr_in));
+    grpc_sockaddr_in* addr4 = reinterpret_cast<grpc_sockaddr_in*>(&addr->addr);
+    addr4->sin_family = GRPC_AF_INET;
+    memcpy(&addr4->sin_addr, ip->bytes, ip->size);
+    addr4->sin_port = netorder_port;
+  } else if (ip->size == 16) {
+    addr->len = static_cast<socklen_t>(sizeof(grpc_sockaddr_in6));
+    grpc_sockaddr_in6* addr6 = (grpc_sockaddr_in6*)&addr->addr;
+    addr6->sin6_family = GRPC_AF_INET6;
+    memcpy(&addr6->sin6_addr, ip->bytes, ip->size);
+    addr6->sin6_port = netorder_port;
+  }
+}
+
+// Returns addresses extracted from \a serverlist.
+grpc_lb_addresses* ProcessServerlist(const xds_grpclb_serverlist* serverlist) {
+  size_t num_valid = 0;
+  /* first pass: count how many are valid in order to allocate the necessary
+   * memory in a single block */
+  for (size_t i = 0; i < serverlist->num_servers; ++i) {
+    if (IsServerValid(serverlist->servers[i], i, true)) ++num_valid;
+  }
+  grpc_lb_addresses* lb_addresses =
+      grpc_lb_addresses_create(num_valid, &lb_token_vtable);
+  /* second pass: actually populate the addresses and LB tokens (aka user data
+   * to the outside world) to be read by the RR policy during its creation.
+   * Given that the validity tests are very cheap, they are performed again
+   * instead of marking the valid ones during the first pass, as this would
+   * incurr in an allocation due to the arbitrary number of server */
+  size_t addr_idx = 0;
+  for (size_t sl_idx = 0; sl_idx < serverlist->num_servers; ++sl_idx) {
+    const xds_grpclb_server* server = serverlist->servers[sl_idx];
+    if (!IsServerValid(serverlist->servers[sl_idx], sl_idx, false)) continue;
+    GPR_ASSERT(addr_idx < num_valid);
+    /* address processing */
+    grpc_resolved_address addr;
+    ParseServer(server, &addr);
+    /* lb token processing */
+    void* user_data;
+    if (server->has_load_balance_token) {
+      const size_t lb_token_max_length =
+          GPR_ARRAY_SIZE(server->load_balance_token);
+      const size_t lb_token_length =
+          strnlen(server->load_balance_token, lb_token_max_length);
+      grpc_slice lb_token_mdstr = grpc_slice_from_copied_buffer(
+          server->load_balance_token, lb_token_length);
+      user_data =
+          (void*)grpc_mdelem_from_slices(GRPC_MDSTR_LB_TOKEN, lb_token_mdstr)
+              .payload;
+    } else {
+      char* uri = grpc_sockaddr_to_uri(&addr);
+      gpr_log(GPR_INFO,
+              "Missing LB token for backend address '%s'. The empty token will "
+              "be used instead",
+              uri);
+      gpr_free(uri);
+      user_data = (void*)GRPC_MDELEM_LB_TOKEN_EMPTY.payload;
+    }
+    grpc_lb_addresses_set_address(lb_addresses, addr_idx, &addr.addr, addr.len,
+                                  false /* is_balancer */,
+                                  nullptr /* balancer_name */, user_data);
+    ++addr_idx;
+  }
+  GPR_ASSERT(addr_idx == num_valid);
+  return lb_addresses;
+}
+
+//
+// XdsLb::BalancerCallState
+//
+
+XdsLb::BalancerCallState::BalancerCallState(
+    RefCountedPtr<LoadBalancingPolicy> parent_xdslb_policy)
+    : InternallyRefCountedWithTracing<BalancerCallState>(&grpc_lb_xds_trace),
+      xdslb_policy_(std::move(parent_xdslb_policy)) {
+  GPR_ASSERT(xdslb_policy_ != nullptr);
+  GPR_ASSERT(!xdslb_policy()->shutting_down_);
+  // Init the LB call. Note that the LB call will progress every time there's
+  // activity in xdslb_policy_->interested_parties(), which is comprised of
+  // the polling entities from client_channel.
+  GPR_ASSERT(xdslb_policy()->server_name_ != nullptr);
+  GPR_ASSERT(xdslb_policy()->server_name_[0] != '\0');
+  const grpc_millis deadline =
+      xdslb_policy()->lb_call_timeout_ms_ == 0
+          ? GRPC_MILLIS_INF_FUTURE
+          : ExecCtx::Get()->Now() + xdslb_policy()->lb_call_timeout_ms_;
+  lb_call_ = grpc_channel_create_pollset_set_call(
+      xdslb_policy()->lb_channel_, nullptr, GRPC_PROPAGATE_DEFAULTS,
+      xdslb_policy_->interested_parties(),
+      GRPC_MDSTR_SLASH_GRPC_DOT_LB_DOT_V1_DOT_LOADBALANCER_SLASH_BALANCELOAD,
+      nullptr, deadline, nullptr);
+  // Init the LB call request payload.
+  xds_grpclb_request* request =
+      xds_grpclb_request_create(xdslb_policy()->server_name_);
+  grpc_slice request_payload_slice = xds_grpclb_request_encode(request);
+  send_message_payload_ =
+      grpc_raw_byte_buffer_create(&request_payload_slice, 1);
+  grpc_slice_unref_internal(request_payload_slice);
+  xds_grpclb_request_destroy(request);
+  // Init other data associated with the LB call.
+  grpc_metadata_array_init(&lb_initial_metadata_recv_);
+  grpc_metadata_array_init(&lb_trailing_metadata_recv_);
+  GRPC_CLOSURE_INIT(&lb_on_initial_request_sent_, OnInitialRequestSentLocked,
+                    this, grpc_combiner_scheduler(xdslb_policy()->combiner()));
+  GRPC_CLOSURE_INIT(&lb_on_balancer_message_received_,
+                    OnBalancerMessageReceivedLocked, this,
+                    grpc_combiner_scheduler(xdslb_policy()->combiner()));
+  GRPC_CLOSURE_INIT(&lb_on_balancer_status_received_,
+                    OnBalancerStatusReceivedLocked, this,
+                    grpc_combiner_scheduler(xdslb_policy()->combiner()));
+}
+
+XdsLb::BalancerCallState::~BalancerCallState() {
+  GPR_ASSERT(lb_call_ != nullptr);
+  grpc_call_unref(lb_call_);
+  grpc_metadata_array_destroy(&lb_initial_metadata_recv_);
+  grpc_metadata_array_destroy(&lb_trailing_metadata_recv_);
+  grpc_byte_buffer_destroy(send_message_payload_);
+  grpc_byte_buffer_destroy(recv_message_payload_);
+  grpc_slice_unref_internal(lb_call_status_details_);
+}
+
+void XdsLb::BalancerCallState::Orphan() {
+  GPR_ASSERT(lb_call_ != nullptr);
+  // If we are here because xdslb_policy wants to cancel the call,
+  // lb_on_balancer_status_received_ will complete the cancellation and clean
+  // up. Otherwise, we are here because xdslb_policy has to orphan a failed
+  // call, then the following cancellation will be a no-op.
+  grpc_call_cancel(lb_call_, nullptr);
+  if (client_load_report_timer_callback_pending_) {
+    grpc_timer_cancel(&client_load_report_timer_);
+  }
+  // Note that the initial ref is hold by lb_on_balancer_status_received_
+  // instead of the caller of this function. So the corresponding unref happens
+  // in lb_on_balancer_status_received_ instead of here.
+}
+
+void XdsLb::BalancerCallState::StartQuery() {
+  GPR_ASSERT(lb_call_ != nullptr);
+  if (grpc_lb_xds_trace.enabled()) {
+    gpr_log(GPR_INFO, "[xdslb %p] Starting LB call (lb_calld: %p, lb_call: %p)",
+            xdslb_policy_.get(), this, lb_call_);
+  }
+  // Create the ops.
+  grpc_call_error call_error;
+  grpc_op ops[3];
+  memset(ops, 0, sizeof(ops));
+  // Op: send initial metadata.
+  grpc_op* op = ops;
+  op->op = GRPC_OP_SEND_INITIAL_METADATA;
+  op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
+  op->reserved = nullptr;
+  op++;
+  // Op: send request message.
+  GPR_ASSERT(send_message_payload_ != nullptr);
+  op->op = GRPC_OP_SEND_MESSAGE;
+  op->data.send_message.send_message = send_message_payload_;
+  op->flags = 0;
+  op->reserved = nullptr;
+  op++;
+  // TODO(roth): We currently track this ref manually.  Once the
+  // ClosureRef API is ready, we should pass the RefCountedPtr<> along
+  // with the callback.
+  auto self = Ref(DEBUG_LOCATION, "on_initial_request_sent");
+  self.release();
+  call_error = grpc_call_start_batch_and_execute(
+      lb_call_, ops, (size_t)(op - ops), &lb_on_initial_request_sent_);
+  GPR_ASSERT(GRPC_CALL_OK == call_error);
+  // Op: recv initial metadata.
+  op = ops;
+  op->op = GRPC_OP_RECV_INITIAL_METADATA;
+  op->data.recv_initial_metadata.recv_initial_metadata =
+      &lb_initial_metadata_recv_;
+  op->flags = 0;
+  op->reserved = nullptr;
+  op++;
+  // Op: recv response.
+  op->op = GRPC_OP_RECV_MESSAGE;
+  op->data.recv_message.recv_message = &recv_message_payload_;
+  op->flags = 0;
+  op->reserved = nullptr;
+  op++;
+  // TODO(roth): We currently track this ref manually.  Once the
+  // ClosureRef API is ready, we should pass the RefCountedPtr<> along
+  // with the callback.
+  self = Ref(DEBUG_LOCATION, "on_message_received");
+  self.release();
+  call_error = grpc_call_start_batch_and_execute(
+      lb_call_, ops, (size_t)(op - ops), &lb_on_balancer_message_received_);
+  GPR_ASSERT(GRPC_CALL_OK == call_error);
+  // Op: recv server status.
+  op = ops;
+  op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
+  op->data.recv_status_on_client.trailing_metadata =
+      &lb_trailing_metadata_recv_;
+  op->data.recv_status_on_client.status = &lb_call_status_;
+  op->data.recv_status_on_client.status_details = &lb_call_status_details_;
+  op->flags = 0;
+  op->reserved = nullptr;
+  op++;
+  // This callback signals the end of the LB call, so it relies on the initial
+  // ref instead of a new ref. When it's invoked, it's the initial ref that is
+  // unreffed.
+  call_error = grpc_call_start_batch_and_execute(
+      lb_call_, ops, (size_t)(op - ops), &lb_on_balancer_status_received_);
+  GPR_ASSERT(GRPC_CALL_OK == call_error);
+}
+
+void XdsLb::BalancerCallState::ScheduleNextClientLoadReportLocked() {
+  const grpc_millis next_client_load_report_time =
+      ExecCtx::Get()->Now() + client_stats_report_interval_;
+  GRPC_CLOSURE_INIT(&client_load_report_closure_,
+                    MaybeSendClientLoadReportLocked, this,
+                    grpc_combiner_scheduler(xdslb_policy()->combiner()));
+  grpc_timer_init(&client_load_report_timer_, next_client_load_report_time,
+                  &client_load_report_closure_);
+  client_load_report_timer_callback_pending_ = true;
+}
+
+void XdsLb::BalancerCallState::MaybeSendClientLoadReportLocked(
+    void* arg, grpc_error* error) {
+  BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
+  XdsLb* xdslb_policy = lb_calld->xdslb_policy();
+  lb_calld->client_load_report_timer_callback_pending_ = false;
+  if (error != GRPC_ERROR_NONE || lb_calld != xdslb_policy->lb_calld_.get()) {
+    lb_calld->Unref(DEBUG_LOCATION, "client_load_report");
+    return;
+  }
+  // If we've already sent the initial request, then we can go ahead and send
+  // the load report. Otherwise, we need to wait until the initial request has
+  // been sent to send this (see OnInitialRequestSentLocked()).
+  if (lb_calld->send_message_payload_ == nullptr) {
+    lb_calld->SendClientLoadReportLocked();
+  } else {
+    lb_calld->client_load_report_is_due_ = true;
+  }
+}
+
+bool XdsLb::BalancerCallState::LoadReportCountersAreZero(
+    xds_grpclb_request* request) {
+  XdsLbClientStats::DroppedCallCounts* drop_entries =
+      static_cast<XdsLbClientStats::DroppedCallCounts*>(
+          request->client_stats.calls_finished_with_drop.arg);
+  return request->client_stats.num_calls_started == 0 &&
+         request->client_stats.num_calls_finished == 0 &&
+         request->client_stats.num_calls_finished_with_client_failed_to_send ==
+             0 &&
+         request->client_stats.num_calls_finished_known_received == 0 &&
+         (drop_entries == nullptr || drop_entries->empty());
+}
+
+void XdsLb::BalancerCallState::SendClientLoadReportLocked() {
+  // Construct message payload.
+  GPR_ASSERT(send_message_payload_ == nullptr);
+  xds_grpclb_request* request =
+      xds_grpclb_load_report_request_create_locked(client_stats_.get());
+  // Skip client load report if the counters were all zero in the last
+  // report and they are still zero in this one.
+  if (LoadReportCountersAreZero(request)) {
+    if (last_client_load_report_counters_were_zero_) {
+      xds_grpclb_request_destroy(request);
+      ScheduleNextClientLoadReportLocked();
+      return;
+    }
+    last_client_load_report_counters_were_zero_ = true;
+  } else {
+    last_client_load_report_counters_were_zero_ = false;
+  }
+  grpc_slice request_payload_slice = xds_grpclb_request_encode(request);
+  send_message_payload_ =
+      grpc_raw_byte_buffer_create(&request_payload_slice, 1);
+  grpc_slice_unref_internal(request_payload_slice);
+  xds_grpclb_request_destroy(request);
+  // Send the report.
+  grpc_op op;
+  memset(&op, 0, sizeof(op));
+  op.op = GRPC_OP_SEND_MESSAGE;
+  op.data.send_message.send_message = send_message_payload_;
+  GRPC_CLOSURE_INIT(&client_load_report_closure_, ClientLoadReportDoneLocked,
+                    this, grpc_combiner_scheduler(xdslb_policy()->combiner()));
+  grpc_call_error call_error = grpc_call_start_batch_and_execute(
+      lb_call_, &op, 1, &client_load_report_closure_);
+  if (GPR_UNLIKELY(call_error != GRPC_CALL_OK)) {
+    gpr_log(GPR_ERROR, "[xdslb %p] call_error=%d", xdslb_policy_.get(),
+            call_error);
+    GPR_ASSERT(GRPC_CALL_OK == call_error);
+  }
+}
+
+void XdsLb::BalancerCallState::ClientLoadReportDoneLocked(void* arg,
+                                                          grpc_error* error) {
+  BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
+  XdsLb* xdslb_policy = lb_calld->xdslb_policy();
+  grpc_byte_buffer_destroy(lb_calld->send_message_payload_);
+  lb_calld->send_message_payload_ = nullptr;
+  if (error != GRPC_ERROR_NONE || lb_calld != xdslb_policy->lb_calld_.get()) {
+    lb_calld->Unref(DEBUG_LOCATION, "client_load_report");
+    return;
+  }
+  lb_calld->ScheduleNextClientLoadReportLocked();
+}
+
+void XdsLb::BalancerCallState::OnInitialRequestSentLocked(void* arg,
+                                                          grpc_error* error) {
+  BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
+  grpc_byte_buffer_destroy(lb_calld->send_message_payload_);
+  lb_calld->send_message_payload_ = nullptr;
+  // If we attempted to send a client load report before the initial request was
+  // sent (and this lb_calld is still in use), send the load report now.
+  if (lb_calld->client_load_report_is_due_ &&
+      lb_calld == lb_calld->xdslb_policy()->lb_calld_.get()) {
+    lb_calld->SendClientLoadReportLocked();
+    lb_calld->client_load_report_is_due_ = false;
+  }
+  lb_calld->Unref(DEBUG_LOCATION, "on_initial_request_sent");
+}
+
+void XdsLb::BalancerCallState::OnBalancerMessageReceivedLocked(
+    void* arg, grpc_error* error) {
+  BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
+  XdsLb* xdslb_policy = lb_calld->xdslb_policy();
+  // Empty payload means the LB call was cancelled.
+  if (lb_calld != xdslb_policy->lb_calld_.get() ||
+      lb_calld->recv_message_payload_ == nullptr) {
+    lb_calld->Unref(DEBUG_LOCATION, "on_message_received");
+    return;
+  }
+  grpc_byte_buffer_reader bbr;
+  grpc_byte_buffer_reader_init(&bbr, lb_calld->recv_message_payload_);
+  grpc_slice response_slice = grpc_byte_buffer_reader_readall(&bbr);
+  grpc_byte_buffer_reader_destroy(&bbr);
+  grpc_byte_buffer_destroy(lb_calld->recv_message_payload_);
+  lb_calld->recv_message_payload_ = nullptr;
+  xds_grpclb_initial_response* initial_response;
+  xds_grpclb_serverlist* serverlist;
+  if (!lb_calld->seen_initial_response_ &&
+      (initial_response = xds_grpclb_initial_response_parse(response_slice)) !=
+          nullptr) {
+    // Have NOT seen initial response, look for initial response.
+    if (initial_response->has_client_stats_report_interval) {
+      lb_calld->client_stats_report_interval_ = GPR_MAX(
+          GPR_MS_PER_SEC, xds_grpclb_duration_to_millis(
+                              &initial_response->client_stats_report_interval));
+      if (grpc_lb_xds_trace.enabled()) {
+        gpr_log(GPR_INFO,
+                "[xdslb %p] Received initial LB response message; "
+                "client load reporting interval = %" PRId64 " milliseconds",
+                xdslb_policy, lb_calld->client_stats_report_interval_);
+      }
+    } else if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO,
+              "[xdslb %p] Received initial LB response message; client load "
+              "reporting NOT enabled",
+              xdslb_policy);
+    }
+    xds_grpclb_initial_response_destroy(initial_response);
+    lb_calld->seen_initial_response_ = true;
+  } else if ((serverlist = xds_grpclb_response_parse_serverlist(
+                  response_slice)) != nullptr) {
+    // Have seen initial response, look for serverlist.
+    GPR_ASSERT(lb_calld->lb_call_ != nullptr);
+    if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO,
+              "[xdslb %p] Serverlist with %" PRIuPTR " servers received",
+              xdslb_policy, serverlist->num_servers);
+      for (size_t i = 0; i < serverlist->num_servers; ++i) {
+        grpc_resolved_address addr;
+        ParseServer(serverlist->servers[i], &addr);
+        char* ipport;
+        grpc_sockaddr_to_string(&ipport, &addr, false);
+        gpr_log(GPR_INFO, "[xdslb %p] Serverlist[%" PRIuPTR "]: %s",
+                xdslb_policy, i, ipport);
+        gpr_free(ipport);
+      }
+    }
+    /* update serverlist */
+    if (serverlist->num_servers > 0) {
+      // Start sending client load report only after we start using the
+      // serverlist returned from the current LB call.
+      if (lb_calld->client_stats_report_interval_ > 0 &&
+          lb_calld->client_stats_ == nullptr) {
+        lb_calld->client_stats_.reset(New<XdsLbClientStats>());
+        // TODO(roth): We currently track this ref manually.  Once the
+        // ClosureRef API is ready, we should pass the RefCountedPtr<> along
+        // with the callback.
+        auto self = lb_calld->Ref(DEBUG_LOCATION, "client_load_report");
+        self.release();
+        lb_calld->ScheduleNextClientLoadReportLocked();
+      }
+      if (xds_grpclb_serverlist_equals(xdslb_policy->serverlist_, serverlist)) {
+        if (grpc_lb_xds_trace.enabled()) {
+          gpr_log(GPR_INFO,
+                  "[xdslb %p] Incoming server list identical to current, "
+                  "ignoring.",
+                  xdslb_policy);
+        }
+        xds_grpclb_destroy_serverlist(serverlist);
+      } else { /* new serverlist */
+        if (xdslb_policy->serverlist_ != nullptr) {
+          /* dispose of the old serverlist */
+          xds_grpclb_destroy_serverlist(xdslb_policy->serverlist_);
+        } else {
+          /* or dispose of the fallback */
+          grpc_lb_addresses_destroy(xdslb_policy->fallback_backend_addresses_);
+          xdslb_policy->fallback_backend_addresses_ = nullptr;
+          if (xdslb_policy->fallback_timer_callback_pending_) {
+            grpc_timer_cancel(&xdslb_policy->lb_fallback_timer_);
+          }
+        }
+        // and update the copy in the XdsLb instance. This
+        // serverlist instance will be destroyed either upon the next
+        // update or when the XdsLb instance is destroyed.
+        xdslb_policy->serverlist_ = serverlist;
+        xdslb_policy->serverlist_index_ = 0;
+        xdslb_policy->CreateOrUpdateRoundRobinPolicyLocked();
+      }
+    } else {
+      if (grpc_lb_xds_trace.enabled()) {
+        gpr_log(GPR_INFO, "[xdslb %p] Received empty server list, ignoring.",
+                xdslb_policy);
+      }
+      xds_grpclb_destroy_serverlist(serverlist);
+    }
+  } else {
+    // No valid initial response or serverlist found.
+    char* response_slice_str =
+        grpc_dump_slice(response_slice, GPR_DUMP_ASCII | GPR_DUMP_HEX);
+    gpr_log(GPR_ERROR,
+            "[xdslb %p] Invalid LB response received: '%s'. Ignoring.",
+            xdslb_policy, response_slice_str);
+    gpr_free(response_slice_str);
+  }
+  grpc_slice_unref_internal(response_slice);
+  if (!xdslb_policy->shutting_down_) {
+    // Keep listening for serverlist updates.
+    grpc_op op;
+    memset(&op, 0, sizeof(op));
+    op.op = GRPC_OP_RECV_MESSAGE;
+    op.data.recv_message.recv_message = &lb_calld->recv_message_payload_;
+    op.flags = 0;
+    op.reserved = nullptr;
+    // Reuse the "OnBalancerMessageReceivedLocked" ref taken in StartQuery().
+    const grpc_call_error call_error = grpc_call_start_batch_and_execute(
+        lb_calld->lb_call_, &op, 1,
+        &lb_calld->lb_on_balancer_message_received_);
+    GPR_ASSERT(GRPC_CALL_OK == call_error);
+  } else {
+    lb_calld->Unref(DEBUG_LOCATION, "on_message_received+grpclb_shutdown");
+  }
+}
+
+void XdsLb::BalancerCallState::OnBalancerStatusReceivedLocked(
+    void* arg, grpc_error* error) {
+  BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
+  XdsLb* xdslb_policy = lb_calld->xdslb_policy();
+  GPR_ASSERT(lb_calld->lb_call_ != nullptr);
+  if (grpc_lb_xds_trace.enabled()) {
+    char* status_details =
+        grpc_slice_to_c_string(lb_calld->lb_call_status_details_);
+    gpr_log(GPR_INFO,
+            "[xdslb %p] Status from LB server received. Status = %d, details "
+            "= '%s', (lb_calld: %p, lb_call: %p), error '%s'",
+            xdslb_policy, lb_calld->lb_call_status_, status_details, lb_calld,
+            lb_calld->lb_call_, grpc_error_string(error));
+    gpr_free(status_details);
+  }
+  xdslb_policy->TryReresolutionLocked(&grpc_lb_xds_trace, GRPC_ERROR_NONE);
+  // If this lb_calld is still in use, this call ended because of a failure so
+  // we want to retry connecting. Otherwise, we have deliberately ended this
+  // call and no further action is required.
+  if (lb_calld == xdslb_policy->lb_calld_.get()) {
+    xdslb_policy->lb_calld_.reset();
+    GPR_ASSERT(!xdslb_policy->shutting_down_);
+    if (lb_calld->seen_initial_response_) {
+      // If we lose connection to the LB server, reset the backoff and restart
+      // the LB call immediately.
+      xdslb_policy->lb_call_backoff_.Reset();
+      xdslb_policy->StartBalancerCallLocked();
+    } else {
+      // If this LB call fails establishing any connection to the LB server,
+      // retry later.
+      xdslb_policy->StartBalancerCallRetryTimerLocked();
+    }
+  }
+  lb_calld->Unref(DEBUG_LOCATION, "lb_call_ended");
+}
+
+//
+// helper code for creating balancer channel
+//
+
+grpc_lb_addresses* ExtractBalancerAddresses(
+    const grpc_lb_addresses* addresses) {
+  size_t num_grpclb_addrs = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (addresses->addresses[i].is_balancer) ++num_grpclb_addrs;
+  }
+  // There must be at least one balancer address, or else the
+  // client_channel would not have chosen this LB policy.
+  GPR_ASSERT(num_grpclb_addrs > 0);
+  grpc_lb_addresses* lb_addresses =
+      grpc_lb_addresses_create(num_grpclb_addrs, nullptr);
+  size_t lb_addresses_idx = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (!addresses->addresses[i].is_balancer) continue;
+    if (GPR_UNLIKELY(addresses->addresses[i].user_data != nullptr)) {
+      gpr_log(GPR_ERROR,
+              "This LB policy doesn't support user data. It will be ignored");
+    }
+    grpc_lb_addresses_set_address(
+        lb_addresses, lb_addresses_idx++, addresses->addresses[i].address.addr,
+        addresses->addresses[i].address.len, false /* is balancer */,
+        addresses->addresses[i].balancer_name, nullptr /* user data */);
+  }
+  GPR_ASSERT(num_grpclb_addrs == lb_addresses_idx);
+  return lb_addresses;
+}
+
+/* Returns the channel args for the LB channel, used to create a bidirectional
+ * stream for the reception of load balancing updates.
+ *
+ * Inputs:
+ *   - \a addresses: corresponding to the balancers.
+ *   - \a response_generator: in order to propagate updates from the resolver
+ *   above the grpclb policy.
+ *   - \a args: other args inherited from the grpclb policy. */
+grpc_channel_args* BuildBalancerChannelArgs(
+    const grpc_lb_addresses* addresses,
+    FakeResolverResponseGenerator* response_generator,
+    const grpc_channel_args* args) {
+  grpc_lb_addresses* lb_addresses = ExtractBalancerAddresses(addresses);
+  // Channel args to remove.
+  static const char* args_to_remove[] = {
+      // LB policy name, since we want to use the default (pick_first) in
+      // the LB channel.
+      GRPC_ARG_LB_POLICY_NAME,
+      // The channel arg for the server URI, since that will be different for
+      // the LB channel than for the parent channel.  The client channel
+      // factory will re-add this arg with the right value.
+      GRPC_ARG_SERVER_URI,
+      // The resolved addresses, which will be generated by the name resolver
+      // used in the LB channel.  Note that the LB channel will use the fake
+      // resolver, so this won't actually generate a query to DNS (or some
+      // other name service).  However, the addresses returned by the fake
+      // resolver will have is_balancer=false, whereas our own addresses have
+      // is_balancer=true.  We need the LB channel to return addresses with
+      // is_balancer=false so that it does not wind up recursively using the
+      // grpclb LB policy, as per the special case logic in client_channel.c.
+      GRPC_ARG_LB_ADDRESSES,
+      // The fake resolver response generator, because we are replacing it
+      // with the one from the grpclb policy, used to propagate updates to
+      // the LB channel.
+      GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR,
+      // The LB channel should use the authority indicated by the target
+      // authority table (see \a grpc_lb_policy_xds_modify_lb_channel_args),
+      // as opposed to the authority from the parent channel.
+      GRPC_ARG_DEFAULT_AUTHORITY,
+      // Just as for \a GRPC_ARG_DEFAULT_AUTHORITY, the LB channel should be
+      // treated as a stand-alone channel and not inherit this argument from the
+      // args of the parent channel.
+      GRPC_SSL_TARGET_NAME_OVERRIDE_ARG,
+  };
+  // Channel args to add.
+  const grpc_arg args_to_add[] = {
+      // New LB addresses.
+      // Note that we pass these in both when creating the LB channel
+      // and via the fake resolver.  The latter is what actually gets used.
+      grpc_lb_addresses_create_channel_arg(lb_addresses),
+      // The fake resolver response generator, which we use to inject
+      // address updates into the LB channel.
+      grpc_core::FakeResolverResponseGenerator::MakeChannelArg(
+          response_generator),
+      // A channel arg indicating the target is a grpclb load balancer.
+      grpc_channel_arg_integer_create(
+          const_cast<char*>(GRPC_ARG_ADDRESS_IS_XDS_LOAD_BALANCER), 1),
+      // A channel arg indicating this is an internal channels, aka it is
+      // owned by components in Core, not by the user application.
+      grpc_channel_arg_integer_create(
+          const_cast<char*>(GRPC_ARG_CHANNELZ_CHANNEL_IS_INTERNAL_CHANNEL), 1),
+  };
+  // Construct channel args.
+  grpc_channel_args* new_args = grpc_channel_args_copy_and_add_and_remove(
+      args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), args_to_add,
+      GPR_ARRAY_SIZE(args_to_add));
+  // Make any necessary modifications for security.
+  new_args = grpc_lb_policy_xds_modify_lb_channel_args(new_args);
+  // Clean up.
+  grpc_lb_addresses_destroy(lb_addresses);
+  return new_args;
+}
+
+//
+// ctor and dtor
+//
+
+XdsLb::XdsLb(const grpc_lb_addresses* addresses,
+             const LoadBalancingPolicy::Args& args)
+    : LoadBalancingPolicy(args),
+      response_generator_(MakeRefCounted<FakeResolverResponseGenerator>()),
+      lb_call_backoff_(
+          BackOff::Options()
+              .set_initial_backoff(GRPC_XDS_INITIAL_CONNECT_BACKOFF_SECONDS *
+                                   1000)
+              .set_multiplier(GRPC_XDS_RECONNECT_BACKOFF_MULTIPLIER)
+              .set_jitter(GRPC_XDS_RECONNECT_JITTER)
+              .set_max_backoff(GRPC_XDS_RECONNECT_MAX_BACKOFF_SECONDS * 1000)) {
+  // Initialization.
+  gpr_mu_init(&lb_channel_mu_);
+  grpc_subchannel_index_ref();
+  GRPC_CLOSURE_INIT(&lb_channel_on_connectivity_changed_,
+                    &XdsLb::OnBalancerChannelConnectivityChangedLocked, this,
+                    grpc_combiner_scheduler(args.combiner));
+  GRPC_CLOSURE_INIT(&on_rr_connectivity_changed_,
+                    &XdsLb::OnRoundRobinConnectivityChangedLocked, this,
+                    grpc_combiner_scheduler(args.combiner));
+  GRPC_CLOSURE_INIT(&on_rr_request_reresolution_,
+                    &XdsLb::OnRoundRobinRequestReresolutionLocked, this,
+                    grpc_combiner_scheduler(args.combiner));
+  grpc_connectivity_state_init(&state_tracker_, GRPC_CHANNEL_IDLE, "xds");
+  // Record server name.
+  const grpc_arg* arg = grpc_channel_args_find(args.args, GRPC_ARG_SERVER_URI);
+  const char* server_uri = grpc_channel_arg_get_string(arg);
+  GPR_ASSERT(server_uri != nullptr);
+  grpc_uri* uri = grpc_uri_parse(server_uri, true);
+  GPR_ASSERT(uri->path[0] != '\0');
+  server_name_ = gpr_strdup(uri->path[0] == '/' ? uri->path + 1 : uri->path);
+  if (grpc_lb_xds_trace.enabled()) {
+    gpr_log(GPR_INFO,
+            "[xdslb %p] Will use '%s' as the server name for LB request.", this,
+            server_name_);
+  }
+  grpc_uri_destroy(uri);
+  // Record LB call timeout.
+  arg = grpc_channel_args_find(args.args, GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS);
+  lb_call_timeout_ms_ = grpc_channel_arg_get_integer(arg, {0, 0, INT_MAX});
+  // Record fallback timeout.
+  arg = grpc_channel_args_find(args.args, GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS);
+  lb_fallback_timeout_ms_ = grpc_channel_arg_get_integer(
+      arg, {GRPC_XDS_DEFAULT_FALLBACK_TIMEOUT_MS, 0, INT_MAX});
+  // Process channel args.
+  ProcessChannelArgsLocked(*args.args);
+}
+
+XdsLb::~XdsLb() {
+  GPR_ASSERT(pending_picks_ == nullptr);
+  gpr_mu_destroy(&lb_channel_mu_);
+  gpr_free((void*)server_name_);
+  grpc_channel_args_destroy(args_);
+  grpc_connectivity_state_destroy(&state_tracker_);
+  if (serverlist_ != nullptr) {
+    xds_grpclb_destroy_serverlist(serverlist_);
+  }
+  if (fallback_backend_addresses_ != nullptr) {
+    grpc_lb_addresses_destroy(fallback_backend_addresses_);
+  }
+  grpc_subchannel_index_unref();
+}
+
+void XdsLb::ShutdownLocked() {
+  grpc_error* error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Channel shutdown");
+  shutting_down_ = true;
+  lb_calld_.reset();
+  if (retry_timer_callback_pending_) {
+    grpc_timer_cancel(&lb_call_retry_timer_);
+  }
+  if (fallback_timer_callback_pending_) {
+    grpc_timer_cancel(&lb_fallback_timer_);
+  }
+  rr_policy_.reset();
+  TryReresolutionLocked(&grpc_lb_xds_trace, GRPC_ERROR_CANCELLED);
+  // We destroy the LB channel here instead of in our destructor because
+  // destroying the channel triggers a last callback to
+  // OnBalancerChannelConnectivityChangedLocked(), and we need to be
+  // alive when that callback is invoked.
+  if (lb_channel_ != nullptr) {
+    gpr_mu_lock(&lb_channel_mu_);
+    grpc_channel_destroy(lb_channel_);
+    lb_channel_ = nullptr;
+    gpr_mu_unlock(&lb_channel_mu_);
+  }
+  grpc_connectivity_state_set(&state_tracker_, GRPC_CHANNEL_SHUTDOWN,
+                              GRPC_ERROR_REF(error), "grpclb_shutdown");
+  // Clear pending picks.
+  PendingPick* pp;
+  while ((pp = pending_picks_) != nullptr) {
+    pending_picks_ = pp->next;
+    pp->pick->connected_subchannel.reset();
+    // Note: pp is deleted in this callback.
+    GRPC_CLOSURE_SCHED(&pp->on_complete, GRPC_ERROR_REF(error));
+  }
+  GRPC_ERROR_UNREF(error);
+}
+
+//
+// public methods
+//
+
+void XdsLb::HandOffPendingPicksLocked(LoadBalancingPolicy* new_policy) {
+  PendingPick* pp;
+  while ((pp = pending_picks_) != nullptr) {
+    pending_picks_ = pp->next;
+    pp->pick->on_complete = pp->original_on_complete;
+    pp->pick->user_data = nullptr;
+    grpc_error* error = GRPC_ERROR_NONE;
+    if (new_policy->PickLocked(pp->pick, &error)) {
+      // Synchronous return; schedule closure.
+      GRPC_CLOSURE_SCHED(pp->pick->on_complete, error);
+    }
+    Delete(pp);
+  }
+}
+
+// Cancel a specific pending pick.
+//
+// A grpclb pick progresses as follows:
+// - If there's a Round Robin policy (rr_policy_) available, it'll be
+//   handed over to the RR policy (in CreateRoundRobinPolicyLocked()). From
+//   that point onwards, it'll be RR's responsibility. For cancellations, that
+//   implies the pick needs also be cancelled by the RR instance.
+// - Otherwise, without an RR instance, picks stay pending at this policy's
+//   level (grpclb), inside the pending_picks_ list. To cancel these,
+//   we invoke the completion closure and set the pick's connected
+//   subchannel to nullptr right here.
+void XdsLb::CancelPickLocked(PickState* pick, grpc_error* error) {
+  PendingPick* pp = pending_picks_;
+  pending_picks_ = nullptr;
+  while (pp != nullptr) {
+    PendingPick* next = pp->next;
+    if (pp->pick == pick) {
+      pick->connected_subchannel.reset();
+      // Note: pp is deleted in this callback.
+      GRPC_CLOSURE_SCHED(&pp->on_complete,
+                         GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+                             "Pick Cancelled", &error, 1));
+    } else {
+      pp->next = pending_picks_;
+      pending_picks_ = pp;
+    }
+    pp = next;
+  }
+  if (rr_policy_ != nullptr) {
+    rr_policy_->CancelPickLocked(pick, GRPC_ERROR_REF(error));
+  }
+  GRPC_ERROR_UNREF(error);
+}
+
+// Cancel all pending picks.
+//
+// A grpclb pick progresses as follows:
+// - If there's a Round Robin policy (rr_policy_) available, it'll be
+//   handed over to the RR policy (in CreateRoundRobinPolicyLocked()). From
+//   that point onwards, it'll be RR's responsibility. For cancellations, that
+//   implies the pick needs also be cancelled by the RR instance.
+// - Otherwise, without an RR instance, picks stay pending at this policy's
+//   level (grpclb), inside the pending_picks_ list. To cancel these,
+//   we invoke the completion closure and set the pick's connected
+//   subchannel to nullptr right here.
+void XdsLb::CancelMatchingPicksLocked(uint32_t initial_metadata_flags_mask,
+                                      uint32_t initial_metadata_flags_eq,
+                                      grpc_error* error) {
+  PendingPick* pp = pending_picks_;
+  pending_picks_ = nullptr;
+  while (pp != nullptr) {
+    PendingPick* next = pp->next;
+    if ((pp->pick->initial_metadata_flags & initial_metadata_flags_mask) ==
+        initial_metadata_flags_eq) {
+      // Note: pp is deleted in this callback.
+      GRPC_CLOSURE_SCHED(&pp->on_complete,
+                         GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+                             "Pick Cancelled", &error, 1));
+    } else {
+      pp->next = pending_picks_;
+      pending_picks_ = pp;
+    }
+    pp = next;
+  }
+  if (rr_policy_ != nullptr) {
+    rr_policy_->CancelMatchingPicksLocked(initial_metadata_flags_mask,
+                                          initial_metadata_flags_eq,
+                                          GRPC_ERROR_REF(error));
+  }
+  GRPC_ERROR_UNREF(error);
+}
+
+void XdsLb::ExitIdleLocked() {
+  if (!started_picking_) {
+    StartPickingLocked();
+  }
+}
+
+void XdsLb::ResetBackoffLocked() {
+  if (lb_channel_ != nullptr) {
+    grpc_channel_reset_connect_backoff(lb_channel_);
+  }
+  if (rr_policy_ != nullptr) {
+    rr_policy_->ResetBackoffLocked();
+  }
+}
+
+bool XdsLb::PickLocked(PickState* pick, grpc_error** error) {
+  PendingPick* pp = PendingPickCreate(pick);
+  bool pick_done = false;
+  if (rr_policy_ != nullptr) {
+    if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO, "[xdslb %p] about to PICK from RR %p", this,
+              rr_policy_.get());
+    }
+    pick_done =
+        PickFromRoundRobinPolicyLocked(false /* force_async */, pp, error);
+  } else {  // rr_policy_ == NULL
+    if (pick->on_complete == nullptr) {
+      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "No pick result available but synchronous result required.");
+      pick_done = true;
+    } else {
+      if (grpc_lb_xds_trace.enabled()) {
+        gpr_log(GPR_INFO,
+                "[xdslb %p] No RR policy. Adding to grpclb's pending picks",
+                this);
+      }
+      AddPendingPick(pp);
+      if (!started_picking_) {
+        StartPickingLocked();
+      }
+      pick_done = false;
+    }
+  }
+  return pick_done;
+}
+
+void XdsLb::FillChildRefsForChannelz(channelz::ChildRefsList* child_subchannels,
+                                     channelz::ChildRefsList* child_channels) {
+  // delegate to the RoundRobin to fill the children subchannels.
+  rr_policy_->FillChildRefsForChannelz(child_subchannels, child_channels);
+  MutexLock lock(&lb_channel_mu_);
+  if (lb_channel_ != nullptr) {
+    grpc_core::channelz::ChannelNode* channel_node =
+        grpc_channel_get_channelz_node(lb_channel_);
+    if (channel_node != nullptr) {
+      child_channels->push_back(channel_node->uuid());
+    }
+  }
+}
+
+grpc_connectivity_state XdsLb::CheckConnectivityLocked(
+    grpc_error** connectivity_error) {
+  return grpc_connectivity_state_get(&state_tracker_, connectivity_error);
+}
+
+void XdsLb::NotifyOnStateChangeLocked(grpc_connectivity_state* current,
+                                      grpc_closure* closure) {
+  grpc_connectivity_state_notify_on_state_change(&state_tracker_, current,
+                                                 closure);
+}
+
+void XdsLb::ProcessChannelArgsLocked(const grpc_channel_args& args) {
+  const grpc_arg* arg = grpc_channel_args_find(&args, GRPC_ARG_LB_ADDRESSES);
+  if (GPR_UNLIKELY(arg == nullptr || arg->type != GRPC_ARG_POINTER)) {
+    // Ignore this update.
+    gpr_log(GPR_ERROR,
+            "[xdslb %p] No valid LB addresses channel arg in update, ignoring.",
+            this);
+    return;
+  }
+  const grpc_lb_addresses* addresses =
+      static_cast<const grpc_lb_addresses*>(arg->value.pointer.p);
+  // Update fallback address list.
+  if (fallback_backend_addresses_ != nullptr) {
+    grpc_lb_addresses_destroy(fallback_backend_addresses_);
+  }
+  fallback_backend_addresses_ = ExtractBackendAddresses(addresses);
+  // Make sure that GRPC_ARG_LB_POLICY_NAME is set in channel args,
+  // since we use this to trigger the client_load_reporting filter.
+  static const char* args_to_remove[] = {GRPC_ARG_LB_POLICY_NAME};
+  grpc_arg new_arg = grpc_channel_arg_string_create(
+      (char*)GRPC_ARG_LB_POLICY_NAME, (char*)"xds");
+  grpc_channel_args_destroy(args_);
+  args_ = grpc_channel_args_copy_and_add_and_remove(
+      &args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), &new_arg, 1);
+  // Construct args for balancer channel.
+  grpc_channel_args* lb_channel_args =
+      BuildBalancerChannelArgs(addresses, response_generator_.get(), &args);
+  // Create balancer channel if needed.
+  if (lb_channel_ == nullptr) {
+    char* uri_str;
+    gpr_asprintf(&uri_str, "fake:///%s", server_name_);
+    gpr_mu_lock(&lb_channel_mu_);
+    lb_channel_ = grpc_client_channel_factory_create_channel(
+        client_channel_factory(), uri_str,
+        GRPC_CLIENT_CHANNEL_TYPE_LOAD_BALANCING, lb_channel_args);
+    gpr_mu_unlock(&lb_channel_mu_);
+    GPR_ASSERT(lb_channel_ != nullptr);
+    gpr_free(uri_str);
+  }
+  // Propagate updates to the LB channel (pick_first) through the fake
+  // resolver.
+  response_generator_->SetResponse(lb_channel_args);
+  grpc_channel_args_destroy(lb_channel_args);
+}
+
+void XdsLb::UpdateLocked(const grpc_channel_args& args) {
+  ProcessChannelArgsLocked(args);
+  // If fallback is configured and the RR policy already exists, update
+  // it with the new fallback addresses.
+  if (lb_fallback_timeout_ms_ > 0 && rr_policy_ != nullptr) {
+    CreateOrUpdateRoundRobinPolicyLocked();
+  }
+  // Start watching the LB channel connectivity for connection, if not
+  // already doing so.
+  if (!watching_lb_channel_) {
+    lb_channel_connectivity_ = grpc_channel_check_connectivity_state(
+        lb_channel_, true /* try to connect */);
+    grpc_channel_element* client_channel_elem = grpc_channel_stack_last_element(
+        grpc_channel_get_channel_stack(lb_channel_));
+    GPR_ASSERT(client_channel_elem->filter == &grpc_client_channel_filter);
+    watching_lb_channel_ = true;
+    // TODO(roth): We currently track this ref manually.  Once the
+    // ClosureRef API is ready, we should pass the RefCountedPtr<> along
+    // with the callback.
+    auto self = Ref(DEBUG_LOCATION, "watch_lb_channel_connectivity");
+    self.release();
+    grpc_client_channel_watch_connectivity_state(
+        client_channel_elem,
+        grpc_polling_entity_create_from_pollset_set(interested_parties()),
+        &lb_channel_connectivity_, &lb_channel_on_connectivity_changed_,
+        nullptr);
+  }
+}
+
+//
+// code for balancer channel and call
+//
+
+void XdsLb::StartPickingLocked() {
+  // Start a timer to fall back.
+  if (lb_fallback_timeout_ms_ > 0 && serverlist_ == nullptr &&
+      !fallback_timer_callback_pending_) {
+    grpc_millis deadline = ExecCtx::Get()->Now() + lb_fallback_timeout_ms_;
+    // TODO(roth): We currently track this ref manually.  Once the
+    // ClosureRef API is ready, we should pass the RefCountedPtr<> along
+    // with the callback.
+    auto self = Ref(DEBUG_LOCATION, "on_fallback_timer");
+    self.release();
+    GRPC_CLOSURE_INIT(&lb_on_fallback_, &XdsLb::OnFallbackTimerLocked, this,
+                      grpc_combiner_scheduler(combiner()));
+    fallback_timer_callback_pending_ = true;
+    grpc_timer_init(&lb_fallback_timer_, deadline, &lb_on_fallback_);
+  }
+  started_picking_ = true;
+  StartBalancerCallLocked();
+}
+
+void XdsLb::StartBalancerCallLocked() {
+  GPR_ASSERT(lb_channel_ != nullptr);
+  if (shutting_down_) return;
+  // Init the LB call data.
+  GPR_ASSERT(lb_calld_ == nullptr);
+  lb_calld_ = MakeOrphanable<BalancerCallState>(Ref());
+  if (grpc_lb_xds_trace.enabled()) {
+    gpr_log(GPR_INFO,
+            "[xdslb %p] Query for backends (lb_channel: %p, lb_calld: %p)",
+            this, lb_channel_, lb_calld_.get());
+  }
+  lb_calld_->StartQuery();
+}
+
+void XdsLb::OnFallbackTimerLocked(void* arg, grpc_error* error) {
+  XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
+  xdslb_policy->fallback_timer_callback_pending_ = false;
+  // If we receive a serverlist after the timer fires but before this callback
+  // actually runs, don't fall back.
+  if (xdslb_policy->serverlist_ == nullptr && !xdslb_policy->shutting_down_ &&
+      error == GRPC_ERROR_NONE) {
+    if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO, "[xdslb %p] Falling back to use backends from resolver",
+              xdslb_policy);
+    }
+    GPR_ASSERT(xdslb_policy->fallback_backend_addresses_ != nullptr);
+    xdslb_policy->CreateOrUpdateRoundRobinPolicyLocked();
+  }
+  xdslb_policy->Unref(DEBUG_LOCATION, "on_fallback_timer");
+}
+
+void XdsLb::StartBalancerCallRetryTimerLocked() {
+  grpc_millis next_try = lb_call_backoff_.NextAttemptTime();
+  if (grpc_lb_xds_trace.enabled()) {
+    gpr_log(GPR_INFO, "[xdslb %p] Connection to LB server lost...", this);
+    grpc_millis timeout = next_try - ExecCtx::Get()->Now();
+    if (timeout > 0) {
+      gpr_log(GPR_INFO, "[xdslb %p] ... retry_timer_active in %" PRId64 "ms.",
+              this, timeout);
+    } else {
+      gpr_log(GPR_INFO, "[xdslb %p] ... retry_timer_active immediately.", this);
+    }
+  }
+  // TODO(roth): We currently track this ref manually.  Once the
+  // ClosureRef API is ready, we should pass the RefCountedPtr<> along
+  // with the callback.
+  auto self = Ref(DEBUG_LOCATION, "on_balancer_call_retry_timer");
+  self.release();
+  GRPC_CLOSURE_INIT(&lb_on_call_retry_, &XdsLb::OnBalancerCallRetryTimerLocked,
+                    this, grpc_combiner_scheduler(combiner()));
+  retry_timer_callback_pending_ = true;
+  grpc_timer_init(&lb_call_retry_timer_, next_try, &lb_on_call_retry_);
+}
+
+void XdsLb::OnBalancerCallRetryTimerLocked(void* arg, grpc_error* error) {
+  XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
+  xdslb_policy->retry_timer_callback_pending_ = false;
+  if (!xdslb_policy->shutting_down_ && error == GRPC_ERROR_NONE &&
+      xdslb_policy->lb_calld_ == nullptr) {
+    if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO, "[xdslb %p] Restarting call to LB server",
+              xdslb_policy);
+    }
+    xdslb_policy->StartBalancerCallLocked();
+  }
+  xdslb_policy->Unref(DEBUG_LOCATION, "on_balancer_call_retry_timer");
+}
+
+// Invoked as part of the update process. It continues watching the LB channel
+// until it shuts down or becomes READY. It's invoked even if the LB channel
+// stayed READY throughout the update (for example if the update is identical).
+void XdsLb::OnBalancerChannelConnectivityChangedLocked(void* arg,
+                                                       grpc_error* error) {
+  XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
+  if (xdslb_policy->shutting_down_) goto done;
+  // Re-initialize the lb_call. This should also take care of updating the
+  // embedded RR policy. Note that the current RR policy, if any, will stay in
+  // effect until an update from the new lb_call is received.
+  switch (xdslb_policy->lb_channel_connectivity_) {
+    case GRPC_CHANNEL_CONNECTING:
+    case GRPC_CHANNEL_TRANSIENT_FAILURE: {
+      // Keep watching the LB channel.
+      grpc_channel_element* client_channel_elem =
+          grpc_channel_stack_last_element(
+              grpc_channel_get_channel_stack(xdslb_policy->lb_channel_));
+      GPR_ASSERT(client_channel_elem->filter == &grpc_client_channel_filter);
+      grpc_client_channel_watch_connectivity_state(
+          client_channel_elem,
+          grpc_polling_entity_create_from_pollset_set(
+              xdslb_policy->interested_parties()),
+          &xdslb_policy->lb_channel_connectivity_,
+          &xdslb_policy->lb_channel_on_connectivity_changed_, nullptr);
+      break;
+    }
+      // The LB channel may be IDLE because it's shut down before the update.
+      // Restart the LB call to kick the LB channel into gear.
+    case GRPC_CHANNEL_IDLE:
+    case GRPC_CHANNEL_READY:
+      xdslb_policy->lb_calld_.reset();
+      if (xdslb_policy->started_picking_) {
+        if (xdslb_policy->retry_timer_callback_pending_) {
+          grpc_timer_cancel(&xdslb_policy->lb_call_retry_timer_);
+        }
+        xdslb_policy->lb_call_backoff_.Reset();
+        xdslb_policy->StartBalancerCallLocked();
+      }
+      // Fall through.
+    case GRPC_CHANNEL_SHUTDOWN:
+    done:
+      xdslb_policy->watching_lb_channel_ = false;
+      xdslb_policy->Unref(DEBUG_LOCATION,
+                          "watch_lb_channel_connectivity_cb_shutdown");
+  }
+}
+
+//
+// PendingPick
+//
+
+// Adds lb_token of selected subchannel (address) to the call's initial
+// metadata.
+grpc_error* AddLbTokenToInitialMetadata(
+    grpc_mdelem lb_token, grpc_linked_mdelem* lb_token_mdelem_storage,
+    grpc_metadata_batch* initial_metadata) {
+  GPR_ASSERT(lb_token_mdelem_storage != nullptr);
+  GPR_ASSERT(!GRPC_MDISNULL(lb_token));
+  return grpc_metadata_batch_add_tail(initial_metadata, lb_token_mdelem_storage,
+                                      lb_token);
+}
+
+// Destroy function used when embedding client stats in call context.
+void DestroyClientStats(void* arg) {
+  static_cast<XdsLbClientStats*>(arg)->Unref();
+}
+
+void XdsLb::PendingPickSetMetadataAndContext(PendingPick* pp) {
+  /* if connected_subchannel is nullptr, no pick has been made by the RR
+   * policy (e.g., all addresses failed to connect). There won't be any
+   * user_data/token available */
+  if (pp->pick->connected_subchannel != nullptr) {
+    if (GPR_LIKELY(!GRPC_MDISNULL(pp->lb_token))) {
+      AddLbTokenToInitialMetadata(GRPC_MDELEM_REF(pp->lb_token),
+                                  &pp->pick->lb_token_mdelem_storage,
+                                  pp->pick->initial_metadata);
+    } else {
+      gpr_log(GPR_ERROR,
+              "[xdslb %p] No LB token for connected subchannel pick %p",
+              pp->xdslb_policy, pp->pick);
+      abort();
+    }
+    // Pass on client stats via context. Passes ownership of the reference.
+    if (pp->client_stats != nullptr) {
+      pp->pick->subchannel_call_context[GRPC_GRPCLB_CLIENT_STATS].value =
+          pp->client_stats.release();
+      pp->pick->subchannel_call_context[GRPC_GRPCLB_CLIENT_STATS].destroy =
+          DestroyClientStats;
+    }
+  } else {
+    pp->client_stats.reset();
+  }
+}
+
+/* The \a on_complete closure passed as part of the pick requires keeping a
+ * reference to its associated round robin instance. We wrap this closure in
+ * order to unref the round robin instance upon its invocation */
+void XdsLb::OnPendingPickComplete(void* arg, grpc_error* error) {
+  PendingPick* pp = static_cast<PendingPick*>(arg);
+  PendingPickSetMetadataAndContext(pp);
+  GRPC_CLOSURE_SCHED(pp->original_on_complete, GRPC_ERROR_REF(error));
+  Delete(pp);
+}
+
+XdsLb::PendingPick* XdsLb::PendingPickCreate(PickState* pick) {
+  PendingPick* pp = New<PendingPick>();
+  pp->xdslb_policy = this;
+  pp->pick = pick;
+  GRPC_CLOSURE_INIT(&pp->on_complete, &XdsLb::OnPendingPickComplete, pp,
+                    grpc_schedule_on_exec_ctx);
+  pp->original_on_complete = pick->on_complete;
+  pick->on_complete = &pp->on_complete;
+  return pp;
+}
+
+void XdsLb::AddPendingPick(PendingPick* pp) {
+  pp->next = pending_picks_;
+  pending_picks_ = pp;
+}
+
+//
+// code for interacting with the RR policy
+//
+
+// Performs a pick over \a rr_policy_. Given that a pick can return
+// immediately (ignoring its completion callback), we need to perform the
+// cleanups this callback would otherwise be responsible for.
+// If \a force_async is true, then we will manually schedule the
+// completion callback even if the pick is available immediately.
+bool XdsLb::PickFromRoundRobinPolicyLocked(bool force_async, PendingPick* pp,
+                                           grpc_error** error) {
+  // Check for drops if we are not using fallback backend addresses.
+  if (serverlist_ != nullptr) {
+    // Look at the index into the serverlist to see if we should drop this call.
+    xds_grpclb_server* server = serverlist_->servers[serverlist_index_++];
+    if (serverlist_index_ == serverlist_->num_servers) {
+      serverlist_index_ = 0;  // Wrap-around.
+    }
+    if (server->drop) {
+      // Update client load reporting stats to indicate the number of
+      // dropped calls.  Note that we have to do this here instead of in
+      // the client_load_reporting filter, because we do not create a
+      // subchannel call (and therefore no client_load_reporting filter)
+      // for dropped calls.
+      if (lb_calld_ != nullptr && lb_calld_->client_stats() != nullptr) {
+        lb_calld_->client_stats()->AddCallDroppedLocked(
+            server->load_balance_token);
+      }
+      if (force_async) {
+        GRPC_CLOSURE_SCHED(pp->original_on_complete, GRPC_ERROR_NONE);
+        Delete(pp);
+        return false;
+      }
+      Delete(pp);
+      return true;
+    }
+  }
+  // Set client_stats and user_data.
+  if (lb_calld_ != nullptr && lb_calld_->client_stats() != nullptr) {
+    pp->client_stats = lb_calld_->client_stats()->Ref();
+  }
+  GPR_ASSERT(pp->pick->user_data == nullptr);
+  pp->pick->user_data = (void**)&pp->lb_token;
+  // Pick via the RR policy.
+  bool pick_done = rr_policy_->PickLocked(pp->pick, error);
+  if (pick_done) {
+    PendingPickSetMetadataAndContext(pp);
+    if (force_async) {
+      GRPC_CLOSURE_SCHED(pp->original_on_complete, *error);
+      *error = GRPC_ERROR_NONE;
+      pick_done = false;
+    }
+    Delete(pp);
+  }
+  // else, the pending pick will be registered and taken care of by the
+  // pending pick list inside the RR policy.  Eventually,
+  // OnPendingPickComplete() will be called, which will (among other
+  // things) add the LB token to the call's initial metadata.
+  return pick_done;
+}
+
+void XdsLb::CreateRoundRobinPolicyLocked(const Args& args) {
+  GPR_ASSERT(rr_policy_ == nullptr);
+  rr_policy_ = LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
+      "round_robin", args);
+  if (GPR_UNLIKELY(rr_policy_ == nullptr)) {
+    gpr_log(GPR_ERROR, "[xdslb %p] Failure creating a RoundRobin policy", this);
+    return;
+  }
+  // TODO(roth): We currently track this ref manually.  Once the new
+  // ClosureRef API is done, pass the RefCountedPtr<> along with the closure.
+  auto self = Ref(DEBUG_LOCATION, "on_rr_reresolution_requested");
+  self.release();
+  rr_policy_->SetReresolutionClosureLocked(&on_rr_request_reresolution_);
+  grpc_error* rr_state_error = nullptr;
+  rr_connectivity_state_ = rr_policy_->CheckConnectivityLocked(&rr_state_error);
+  // Connectivity state is a function of the RR policy updated/created.
+  UpdateConnectivityStateFromRoundRobinPolicyLocked(rr_state_error);
+  // Add the gRPC LB's interested_parties pollset_set to that of the newly
+  // created RR policy. This will make the RR policy progress upon activity on
+  // gRPC LB, which in turn is tied to the application's call.
+  grpc_pollset_set_add_pollset_set(rr_policy_->interested_parties(),
+                                   interested_parties());
+  // Subscribe to changes to the connectivity of the new RR.
+  // TODO(roth): We currently track this ref manually.  Once the new
+  // ClosureRef API is done, pass the RefCountedPtr<> along with the closure.
+  self = Ref(DEBUG_LOCATION, "on_rr_connectivity_changed");
+  self.release();
+  rr_policy_->NotifyOnStateChangeLocked(&rr_connectivity_state_,
+                                        &on_rr_connectivity_changed_);
+  rr_policy_->ExitIdleLocked();
+  // Send pending picks to RR policy.
+  PendingPick* pp;
+  while ((pp = pending_picks_)) {
+    pending_picks_ = pp->next;
+    if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO,
+              "[xdslb %p] Pending pick about to (async) PICK from RR %p", this,
+              rr_policy_.get());
+    }
+    grpc_error* error = GRPC_ERROR_NONE;
+    PickFromRoundRobinPolicyLocked(true /* force_async */, pp, &error);
+  }
+}
+
+grpc_channel_args* XdsLb::CreateRoundRobinPolicyArgsLocked() {
+  grpc_lb_addresses* addresses;
+  bool is_backend_from_grpclb_load_balancer = false;
+  if (serverlist_ != nullptr) {
+    GPR_ASSERT(serverlist_->num_servers > 0);
+    addresses = ProcessServerlist(serverlist_);
+    is_backend_from_grpclb_load_balancer = true;
+  } else {
+    // If CreateOrUpdateRoundRobinPolicyLocked() is invoked when we haven't
+    // received any serverlist from the balancer, we use the fallback backends
+    // returned by the resolver. Note that the fallback backend list may be
+    // empty, in which case the new round_robin policy will keep the requested
+    // picks pending.
+    GPR_ASSERT(fallback_backend_addresses_ != nullptr);
+    addresses = grpc_lb_addresses_copy(fallback_backend_addresses_);
+  }
+  GPR_ASSERT(addresses != nullptr);
+  // Replace the LB addresses in the channel args that we pass down to
+  // the subchannel.
+  static const char* keys_to_remove[] = {GRPC_ARG_LB_ADDRESSES};
+  const grpc_arg args_to_add[] = {
+      grpc_lb_addresses_create_channel_arg(addresses),
+      // A channel arg indicating if the target is a backend inferred from a
+      // grpclb load balancer.
+      grpc_channel_arg_integer_create(
+          const_cast<char*>(GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER),
+          is_backend_from_grpclb_load_balancer),
+  };
+  grpc_channel_args* args = grpc_channel_args_copy_and_add_and_remove(
+      args_, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove), args_to_add,
+      GPR_ARRAY_SIZE(args_to_add));
+  grpc_lb_addresses_destroy(addresses);
+  return args;
+}
+
+void XdsLb::CreateOrUpdateRoundRobinPolicyLocked() {
+  if (shutting_down_) return;
+  grpc_channel_args* args = CreateRoundRobinPolicyArgsLocked();
+  GPR_ASSERT(args != nullptr);
+  if (rr_policy_ != nullptr) {
+    if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO, "[xdslb %p] Updating RR policy %p", this,
+              rr_policy_.get());
+    }
+    rr_policy_->UpdateLocked(*args);
+  } else {
+    LoadBalancingPolicy::Args lb_policy_args;
+    lb_policy_args.combiner = combiner();
+    lb_policy_args.client_channel_factory = client_channel_factory();
+    lb_policy_args.args = args;
+    CreateRoundRobinPolicyLocked(lb_policy_args);
+    if (grpc_lb_xds_trace.enabled()) {
+      gpr_log(GPR_INFO, "[xdslb %p] Created new RR policy %p", this,
+              rr_policy_.get());
+    }
+  }
+  grpc_channel_args_destroy(args);
+}
+
+void XdsLb::OnRoundRobinRequestReresolutionLocked(void* arg,
+                                                  grpc_error* error) {
+  XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
+  if (xdslb_policy->shutting_down_ || error != GRPC_ERROR_NONE) {
+    xdslb_policy->Unref(DEBUG_LOCATION, "on_rr_reresolution_requested");
+    return;
+  }
+  if (grpc_lb_xds_trace.enabled()) {
+    gpr_log(
+        GPR_INFO,
+        "[xdslb %p] Re-resolution requested from the internal RR policy (%p).",
+        xdslb_policy, xdslb_policy->rr_policy_.get());
+  }
+  // If we are talking to a balancer, we expect to get updated addresses form
+  // the balancer, so we can ignore the re-resolution request from the RR
+  // policy. Otherwise, handle the re-resolution request using the
+  // grpclb policy's original re-resolution closure.
+  if (xdslb_policy->lb_calld_ == nullptr ||
+      !xdslb_policy->lb_calld_->seen_initial_response()) {
+    xdslb_policy->TryReresolutionLocked(&grpc_lb_xds_trace, GRPC_ERROR_NONE);
+  }
+  // Give back the wrapper closure to the RR policy.
+  xdslb_policy->rr_policy_->SetReresolutionClosureLocked(
+      &xdslb_policy->on_rr_request_reresolution_);
+}
+
+void XdsLb::UpdateConnectivityStateFromRoundRobinPolicyLocked(
+    grpc_error* rr_state_error) {
+  const grpc_connectivity_state curr_glb_state =
+      grpc_connectivity_state_check(&state_tracker_);
+  /* The new connectivity status is a function of the previous one and the new
+   * input coming from the status of the RR policy.
+   *
+   *  current state (grpclb's)
+   *  |
+   *  v  || I  |  C  |  R  |  TF  |  SD  |  <- new state (RR's)
+   *  ===++====+=====+=====+======+======+
+   *   I || I  |  C  |  R  | [I]  | [I]  |
+   *  ---++----+-----+-----+------+------+
+   *   C || I  |  C  |  R  | [C]  | [C]  |
+   *  ---++----+-----+-----+------+------+
+   *   R || I  |  C  |  R  | [R]  | [R]  |
+   *  ---++----+-----+-----+------+------+
+   *  TF || I  |  C  |  R  | [TF] | [TF] |
+   *  ---++----+-----+-----+------+------+
+   *  SD || NA |  NA |  NA |  NA  |  NA  | (*)
+   *  ---++----+-----+-----+------+------+
+   *
+   * A [STATE] indicates that the old RR policy is kept. In those cases, STATE
+   * is the current state of grpclb, which is left untouched.
+   *
+   *  In summary, if the new state is TRANSIENT_FAILURE or SHUTDOWN, stick to
+   *  the previous RR instance.
+   *
+   *  Note that the status is never updated to SHUTDOWN as a result of calling
+   *  this function. Only glb_shutdown() has the power to set that state.
+   *
+   *  (*) This function mustn't be called during shutting down. */
+  GPR_ASSERT(curr_glb_state != GRPC_CHANNEL_SHUTDOWN);
+  switch (rr_connectivity_state_) {
+    case GRPC_CHANNEL_TRANSIENT_FAILURE:
+    case GRPC_CHANNEL_SHUTDOWN:
+      GPR_ASSERT(rr_state_error != GRPC_ERROR_NONE);
+      break;
+    case GRPC_CHANNEL_IDLE:
+    case GRPC_CHANNEL_CONNECTING:
+    case GRPC_CHANNEL_READY:
+      GPR_ASSERT(rr_state_error == GRPC_ERROR_NONE);
+  }
+  if (grpc_lb_xds_trace.enabled()) {
+    gpr_log(
+        GPR_INFO,
+        "[xdslb %p] Setting grpclb's state to %s from new RR policy %p state.",
+        this, grpc_connectivity_state_name(rr_connectivity_state_),
+        rr_policy_.get());
+  }
+  grpc_connectivity_state_set(&state_tracker_, rr_connectivity_state_,
+                              rr_state_error,
+                              "update_lb_connectivity_status_locked");
+}
+
+void XdsLb::OnRoundRobinConnectivityChangedLocked(void* arg,
+                                                  grpc_error* error) {
+  XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
+  if (xdslb_policy->shutting_down_) {
+    xdslb_policy->Unref(DEBUG_LOCATION, "on_rr_connectivity_changed");
+    return;
+  }
+  xdslb_policy->UpdateConnectivityStateFromRoundRobinPolicyLocked(
+      GRPC_ERROR_REF(error));
+  // Resubscribe. Reuse the "on_rr_connectivity_changed" ref.
+  xdslb_policy->rr_policy_->NotifyOnStateChangeLocked(
+      &xdslb_policy->rr_connectivity_state_,
+      &xdslb_policy->on_rr_connectivity_changed_);
+}
+
+//
+// factory
+//
+
+class XdsFactory : public LoadBalancingPolicyFactory {
+ public:
+  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+      const LoadBalancingPolicy::Args& args) const override {
+    /* Count the number of gRPC-LB addresses. There must be at least one. */
+    const grpc_arg* arg =
+        grpc_channel_args_find(args.args, GRPC_ARG_LB_ADDRESSES);
+    if (arg == nullptr || arg->type != GRPC_ARG_POINTER) {
+      return nullptr;
+    }
+    grpc_lb_addresses* addresses =
+        static_cast<grpc_lb_addresses*>(arg->value.pointer.p);
+    size_t num_grpclb_addrs = 0;
+    for (size_t i = 0; i < addresses->num_addresses; ++i) {
+      if (addresses->addresses[i].is_balancer) ++num_grpclb_addrs;
+    }
+    if (num_grpclb_addrs == 0) return nullptr;
+    return OrphanablePtr<LoadBalancingPolicy>(New<XdsLb>(addresses, args));
+  }
+
+  const char* name() const override { return "xds"; }
+};
+
+}  // namespace
+
+}  // namespace grpc_core
+
+//
+// Plugin registration
+//
+
+void grpc_lb_policy_xds_init() {
+  grpc_core::LoadBalancingPolicyRegistry::Builder::
+      RegisterLoadBalancingPolicyFactory(
+          grpc_core::UniquePtr<grpc_core::LoadBalancingPolicyFactory>(
+              grpc_core::New<grpc_core::XdsFactory>()));
+}
+
+void grpc_lb_policy_xds_shutdown() {}

src/core/ext/filters/client_channel/lb_policy/xds/xds.h

@@ -0,0 +1,36 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_H
+
+#include <grpc/support/port_platform.h>
+
+/** Channel arg indicating if a target corresponding to the address is grpclb
+ * loadbalancer. The type of this arg is an integer and the value is treated as
+ * a bool. */
+#define GRPC_ARG_ADDRESS_IS_XDS_LOAD_BALANCER \
+  "grpc.address_is_xds_load_balancer"
+/** Channel arg indicating if a target corresponding to the address is a backend
+ * received from a balancer. The type of this arg is an integer and the value is
+ * treated as a bool. */
+#define GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER \
+  "grpc.address_is_backend_from_xds_load_balancer"
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_H \
+        */

src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.cc

@@ -0,0 +1,26 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h"
+
+grpc_channel_args* grpc_lb_policy_xds_modify_lb_channel_args(
+    grpc_channel_args* args) {
+  return args;
+}

src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h

@@ -0,0 +1,36 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CHANNEL_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CHANNEL_H
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+
+/// Makes any necessary modifications to \a args for use in the xds
+/// balancer channel.
+///
+/// Takes ownership of \a args.
+///
+/// Caller takes ownership of the returned args.
+grpc_channel_args* grpc_lb_policy_xds_modify_lb_channel_args(
+    grpc_channel_args* args);
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CHANNEL_H \
+        */

src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_secure.cc

@@ -0,0 +1,107 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+#include <string.h>
+
+#include "src/core/ext/filters/client_channel/client_channel.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/iomgr/sockaddr_utils.h"
+#include "src/core/lib/security/credentials/credentials.h"
+#include "src/core/lib/security/transport/target_authority_table.h"
+#include "src/core/lib/slice/slice_internal.h"
+
+namespace grpc_core {
+namespace {
+
+int BalancerNameCmp(const grpc_core::UniquePtr<char>& a,
+                    const grpc_core::UniquePtr<char>& b) {
+  return strcmp(a.get(), b.get());
+}
+
+RefCountedPtr<TargetAuthorityTable> CreateTargetAuthorityTable(
+    grpc_lb_addresses* addresses) {
+  TargetAuthorityTable::Entry* target_authority_entries =
+      static_cast<TargetAuthorityTable::Entry*>(gpr_zalloc(
+          sizeof(*target_authority_entries) * addresses->num_addresses));
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    char* addr_str;
+    GPR_ASSERT(grpc_sockaddr_to_string(
+                   &addr_str, &addresses->addresses[i].address, true) > 0);
+    target_authority_entries[i].key = grpc_slice_from_copied_string(addr_str);
+    target_authority_entries[i].value.reset(
+        gpr_strdup(addresses->addresses[i].balancer_name));
+    gpr_free(addr_str);
+  }
+  RefCountedPtr<TargetAuthorityTable> target_authority_table =
+      TargetAuthorityTable::Create(addresses->num_addresses,
+                                   target_authority_entries, BalancerNameCmp);
+  gpr_free(target_authority_entries);
+  return target_authority_table;
+}
+
+}  // namespace
+}  // namespace grpc_core
+
+grpc_channel_args* grpc_lb_policy_xds_modify_lb_channel_args(
+    grpc_channel_args* args) {
+  const char* args_to_remove[1];
+  size_t num_args_to_remove = 0;
+  grpc_arg args_to_add[2];
+  size_t num_args_to_add = 0;
+  // Add arg for targets info table.
+  const grpc_arg* arg = grpc_channel_args_find(args, GRPC_ARG_LB_ADDRESSES);
+  GPR_ASSERT(arg != nullptr);
+  GPR_ASSERT(arg->type == GRPC_ARG_POINTER);
+  grpc_lb_addresses* addresses =
+      static_cast<grpc_lb_addresses*>(arg->value.pointer.p);
+  grpc_core::RefCountedPtr<grpc_core::TargetAuthorityTable>
+      target_authority_table = grpc_core::CreateTargetAuthorityTable(addresses);
+  args_to_add[num_args_to_add++] =
+      grpc_core::CreateTargetAuthorityTableChannelArg(
+          target_authority_table.get());
+  // Substitute the channel credentials with a version without call
+  // credentials: the load balancer is not necessarily trusted to handle
+  // bearer token credentials.
+  grpc_channel_credentials* channel_credentials =
+      grpc_channel_credentials_find_in_args(args);
+  grpc_channel_credentials* creds_sans_call_creds = nullptr;
+  if (channel_credentials != nullptr) {
+    creds_sans_call_creds =
+        grpc_channel_credentials_duplicate_without_call_credentials(
+            channel_credentials);
+    GPR_ASSERT(creds_sans_call_creds != nullptr);
+    args_to_remove[num_args_to_remove++] = GRPC_ARG_CHANNEL_CREDENTIALS;
+    args_to_add[num_args_to_add++] =
+        grpc_channel_credentials_to_arg(creds_sans_call_creds);
+  }
+  grpc_channel_args* result = grpc_channel_args_copy_and_add_and_remove(
+      args, args_to_remove, num_args_to_remove, args_to_add, num_args_to_add);
+  // Clean up.
+  grpc_channel_args_destroy(args);
+  if (creds_sans_call_creds != nullptr) {
+    grpc_channel_credentials_unref(creds_sans_call_creds);
+  }
+  return result;
+}

src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.cc

@@ -0,0 +1,85 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h"
+
+#include <grpc/support/atm.h>
+#include <grpc/support/string_util.h>
+#include <string.h>
+
+namespace grpc_core {
+
+void XdsLbClientStats::AddCallStarted() {
+  gpr_atm_full_fetch_add(&num_calls_started_, (gpr_atm)1);
+}
+
+void XdsLbClientStats::AddCallFinished(bool finished_with_client_failed_to_send,
+                                       bool finished_known_received) {
+  gpr_atm_full_fetch_add(&num_calls_finished_, (gpr_atm)1);
+  if (finished_with_client_failed_to_send) {
+    gpr_atm_full_fetch_add(&num_calls_finished_with_client_failed_to_send_,
+                           (gpr_atm)1);
+  }
+  if (finished_known_received) {
+    gpr_atm_full_fetch_add(&num_calls_finished_known_received_, (gpr_atm)1);
+  }
+}
+
+void XdsLbClientStats::AddCallDroppedLocked(char* token) {
+  // Increment num_calls_started and num_calls_finished.
+  gpr_atm_full_fetch_add(&num_calls_started_, (gpr_atm)1);
+  gpr_atm_full_fetch_add(&num_calls_finished_, (gpr_atm)1);
+  // Record the drop.
+  if (drop_token_counts_ == nullptr) {
+    drop_token_counts_.reset(New<DroppedCallCounts>());
+  }
+  for (size_t i = 0; i < drop_token_counts_->size(); ++i) {
+    if (strcmp((*drop_token_counts_)[i].token.get(), token) == 0) {
+      ++(*drop_token_counts_)[i].count;
+      return;
+    }
+  }
+  // Not found, so add a new entry.
+  drop_token_counts_->emplace_back(UniquePtr<char>(gpr_strdup(token)), 1);
+}
+
+namespace {
+
+void AtomicGetAndResetCounter(int64_t* value, gpr_atm* counter) {
+  *value = static_cast<int64_t>(gpr_atm_full_xchg(counter, (gpr_atm)0));
+}
+
+}  // namespace
+
+void XdsLbClientStats::GetLocked(
+    int64_t* num_calls_started, int64_t* num_calls_finished,
+    int64_t* num_calls_finished_with_client_failed_to_send,
+    int64_t* num_calls_finished_known_received,
+    UniquePtr<DroppedCallCounts>* drop_token_counts) {
+  AtomicGetAndResetCounter(num_calls_started, &num_calls_started_);
+  AtomicGetAndResetCounter(num_calls_finished, &num_calls_finished_);
+  AtomicGetAndResetCounter(num_calls_finished_with_client_failed_to_send,
+                           &num_calls_finished_with_client_failed_to_send_);
+  AtomicGetAndResetCounter(num_calls_finished_known_received,
+                           &num_calls_finished_known_received_);
+  *drop_token_counts = std::move(drop_token_counts_);
+}
+
+}  // namespace grpc_core

src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h

@@ -0,0 +1,72 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CLIENT_STATS_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CLIENT_STATS_H
+
+#include <grpc/support/port_platform.h>
+
+#include <grpc/support/atm.h>
+
+#include "src/core/lib/gprpp/inlined_vector.h"
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/gprpp/ref_counted.h"
+
+namespace grpc_core {
+
+class XdsLbClientStats : public RefCounted<XdsLbClientStats> {
+ public:
+  struct DropTokenCount {
+    UniquePtr<char> token;
+    int64_t count;
+
+    DropTokenCount(UniquePtr<char> token, int64_t count)
+        : token(std::move(token)), count(count) {}
+  };
+
+  typedef InlinedVector<DropTokenCount, 10> DroppedCallCounts;
+
+  XdsLbClientStats() {}
+
+  void AddCallStarted();
+  void AddCallFinished(bool finished_with_client_failed_to_send,
+                       bool finished_known_received);
+
+  // This method is not thread-safe; caller must synchronize.
+  void AddCallDroppedLocked(char* token);
+
+  // This method is not thread-safe; caller must synchronize.
+  void GetLocked(int64_t* num_calls_started, int64_t* num_calls_finished,
+                 int64_t* num_calls_finished_with_client_failed_to_send,
+                 int64_t* num_calls_finished_known_received,
+                 UniquePtr<DroppedCallCounts>* drop_token_counts);
+
+ private:
+  // This field must only be accessed via *_locked() methods.
+  UniquePtr<DroppedCallCounts> drop_token_counts_;
+  // These fields may be accessed from multiple threads at a time.
+  gpr_atm num_calls_started_ = 0;
+  gpr_atm num_calls_finished_ = 0;
+  gpr_atm num_calls_finished_with_client_failed_to_send_ = 0;
+  gpr_atm num_calls_finished_known_received_ = 0;
+};
+
+}  // namespace grpc_core
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CLIENT_STATS_H \
+        */

src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc

@@ -0,0 +1,307 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "pb_decode.h"
+#include "pb_encode.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h"
+
+#include <grpc/support/alloc.h>
+
+/* invoked once for every Server in ServerList */
+static bool count_serverlist(pb_istream_t* stream, const pb_field_t* field,
+                             void** arg) {
+  xds_grpclb_serverlist* sl = static_cast<xds_grpclb_serverlist*>(*arg);
+  xds_grpclb_server server;
+  if (GPR_UNLIKELY(!pb_decode(stream, grpc_lb_v1_Server_fields, &server))) {
+    gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(stream));
+    return false;
+  }
+  ++sl->num_servers;
+  return true;
+}
+
+typedef struct decode_serverlist_arg {
+  /* The decoding callback is invoked once per server in serverlist. Remember
+   * which index of the serverlist are we currently decoding */
+  size_t decoding_idx;
+  /* The decoded serverlist */
+  xds_grpclb_serverlist* serverlist;
+} decode_serverlist_arg;
+
+/* invoked once for every Server in ServerList */
+static bool decode_serverlist(pb_istream_t* stream, const pb_field_t* field,
+                              void** arg) {
+  decode_serverlist_arg* dec_arg = static_cast<decode_serverlist_arg*>(*arg);
+  GPR_ASSERT(dec_arg->serverlist->num_servers >= dec_arg->decoding_idx);
+  xds_grpclb_server* server =
+      static_cast<xds_grpclb_server*>(gpr_zalloc(sizeof(xds_grpclb_server)));
+  if (GPR_UNLIKELY(!pb_decode(stream, grpc_lb_v1_Server_fields, server))) {
+    gpr_free(server);
+    gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(stream));
+    return false;
+  }
+  dec_arg->serverlist->servers[dec_arg->decoding_idx++] = server;
+  return true;
+}
+
+xds_grpclb_request* xds_grpclb_request_create(const char* lb_service_name) {
+  xds_grpclb_request* req =
+      static_cast<xds_grpclb_request*>(gpr_malloc(sizeof(xds_grpclb_request)));
+  req->has_client_stats = false;
+  req->has_initial_request = true;
+  req->initial_request.has_name = true;
+  strncpy(req->initial_request.name, lb_service_name,
+          XDS_SERVICE_NAME_MAX_LENGTH);
+  return req;
+}
+
+static void populate_timestamp(gpr_timespec timestamp,
+                               xds_grpclb_timestamp* timestamp_pb) {
+  timestamp_pb->has_seconds = true;
+  timestamp_pb->seconds = timestamp.tv_sec;
+  timestamp_pb->has_nanos = true;
+  timestamp_pb->nanos = timestamp.tv_nsec;
+}
+
+static bool encode_string(pb_ostream_t* stream, const pb_field_t* field,
+                          void* const* arg) {
+  char* str = static_cast<char*>(*arg);
+  if (!pb_encode_tag_for_field(stream, field)) return false;
+  return pb_encode_string(stream, reinterpret_cast<uint8_t*>(str), strlen(str));
+}
+
+static bool encode_drops(pb_ostream_t* stream, const pb_field_t* field,
+                         void* const* arg) {
+  grpc_core::XdsLbClientStats::DroppedCallCounts* drop_entries =
+      static_cast<grpc_core::XdsLbClientStats::DroppedCallCounts*>(*arg);
+  if (drop_entries == nullptr) return true;
+  for (size_t i = 0; i < drop_entries->size(); ++i) {
+    if (!pb_encode_tag_for_field(stream, field)) return false;
+    grpc_lb_v1_ClientStatsPerToken drop_message;
+    drop_message.load_balance_token.funcs.encode = encode_string;
+    drop_message.load_balance_token.arg = (*drop_entries)[i].token.get();
+    drop_message.has_num_calls = true;
+    drop_message.num_calls = (*drop_entries)[i].count;
+    if (!pb_encode_submessage(stream, grpc_lb_v1_ClientStatsPerToken_fields,
+                              &drop_message)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+xds_grpclb_request* xds_grpclb_load_report_request_create_locked(
+    grpc_core::XdsLbClientStats* client_stats) {
+  xds_grpclb_request* req =
+      static_cast<xds_grpclb_request*>(gpr_zalloc(sizeof(xds_grpclb_request)));
+  req->has_client_stats = true;
+  req->client_stats.has_timestamp = true;
+  populate_timestamp(gpr_now(GPR_CLOCK_REALTIME), &req->client_stats.timestamp);
+  req->client_stats.has_num_calls_started = true;
+  req->client_stats.has_num_calls_finished = true;
+  req->client_stats.has_num_calls_finished_with_client_failed_to_send = true;
+  req->client_stats.has_num_calls_finished_with_client_failed_to_send = true;
+  req->client_stats.has_num_calls_finished_known_received = true;
+  req->client_stats.calls_finished_with_drop.funcs.encode = encode_drops;
+  grpc_core::UniquePtr<grpc_core::XdsLbClientStats::DroppedCallCounts>
+      drop_counts;
+  client_stats->GetLocked(
+      &req->client_stats.num_calls_started,
+      &req->client_stats.num_calls_finished,
+      &req->client_stats.num_calls_finished_with_client_failed_to_send,
+      &req->client_stats.num_calls_finished_known_received, &drop_counts);
+  // Will be deleted in xds_grpclb_request_destroy().
+  req->client_stats.calls_finished_with_drop.arg = drop_counts.release();
+  return req;
+}
+
+grpc_slice xds_grpclb_request_encode(const xds_grpclb_request* request) {
+  size_t encoded_length;
+  pb_ostream_t sizestream;
+  pb_ostream_t outputstream;
+  grpc_slice slice;
+  memset(&sizestream, 0, sizeof(pb_ostream_t));
+  pb_encode(&sizestream, grpc_lb_v1_LoadBalanceRequest_fields, request);
+  encoded_length = sizestream.bytes_written;
+
+  slice = GRPC_SLICE_MALLOC(encoded_length);
+  outputstream =
+      pb_ostream_from_buffer(GRPC_SLICE_START_PTR(slice), encoded_length);
+  GPR_ASSERT(pb_encode(&outputstream, grpc_lb_v1_LoadBalanceRequest_fields,
+                       request) != 0);
+  return slice;
+}
+
+void xds_grpclb_request_destroy(xds_grpclb_request* request) {
+  if (request->has_client_stats) {
+    grpc_core::XdsLbClientStats::DroppedCallCounts* drop_entries =
+        static_cast<grpc_core::XdsLbClientStats::DroppedCallCounts*>(
+            request->client_stats.calls_finished_with_drop.arg);
+    grpc_core::Delete(drop_entries);
+  }
+  gpr_free(request);
+}
+
+typedef grpc_lb_v1_LoadBalanceResponse xds_grpclb_response;
+xds_grpclb_initial_response* xds_grpclb_initial_response_parse(
+    grpc_slice encoded_xds_grpclb_response) {
+  pb_istream_t stream =
+      pb_istream_from_buffer(GRPC_SLICE_START_PTR(encoded_xds_grpclb_response),
+                             GRPC_SLICE_LENGTH(encoded_xds_grpclb_response));
+  xds_grpclb_response res;
+  memset(&res, 0, sizeof(xds_grpclb_response));
+  if (GPR_UNLIKELY(
+          !pb_decode(&stream, grpc_lb_v1_LoadBalanceResponse_fields, &res))) {
+    gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(&stream));
+    return nullptr;
+  }
+
+  if (!res.has_initial_response) return nullptr;
+
+  xds_grpclb_initial_response* initial_res =
+      static_cast<xds_grpclb_initial_response*>(
+          gpr_malloc(sizeof(xds_grpclb_initial_response)));
+  memcpy(initial_res, &res.initial_response,
+         sizeof(xds_grpclb_initial_response));
+
+  return initial_res;
+}
+
+xds_grpclb_serverlist* xds_grpclb_response_parse_serverlist(
+    grpc_slice encoded_xds_grpclb_response) {
+  pb_istream_t stream =
+      pb_istream_from_buffer(GRPC_SLICE_START_PTR(encoded_xds_grpclb_response),
+                             GRPC_SLICE_LENGTH(encoded_xds_grpclb_response));
+  pb_istream_t stream_at_start = stream;
+  xds_grpclb_serverlist* sl = static_cast<xds_grpclb_serverlist*>(
+      gpr_zalloc(sizeof(xds_grpclb_serverlist)));
+  xds_grpclb_response res;
+  memset(&res, 0, sizeof(xds_grpclb_response));
+  // First pass: count number of servers.
+  res.server_list.servers.funcs.decode = count_serverlist;
+  res.server_list.servers.arg = sl;
+  bool status = pb_decode(&stream, grpc_lb_v1_LoadBalanceResponse_fields, &res);
+  if (GPR_UNLIKELY(!status)) {
+    gpr_free(sl);
+    gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(&stream));
+    return nullptr;
+  }
+  // Second pass: populate servers.
+  if (sl->num_servers > 0) {
+    sl->servers = static_cast<xds_grpclb_server**>(
+        gpr_zalloc(sizeof(xds_grpclb_server*) * sl->num_servers));
+    decode_serverlist_arg decode_arg;
+    memset(&decode_arg, 0, sizeof(decode_arg));
+    decode_arg.serverlist = sl;
+    res.server_list.servers.funcs.decode = decode_serverlist;
+    res.server_list.servers.arg = &decode_arg;
+    status = pb_decode(&stream_at_start, grpc_lb_v1_LoadBalanceResponse_fields,
+                       &res);
+    if (GPR_UNLIKELY(!status)) {
+      xds_grpclb_destroy_serverlist(sl);
+      gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(&stream));
+      return nullptr;
+    }
+  }
+  return sl;
+}
+
+void xds_grpclb_destroy_serverlist(xds_grpclb_serverlist* serverlist) {
+  if (serverlist == nullptr) {
+    return;
+  }
+  for (size_t i = 0; i < serverlist->num_servers; i++) {
+    gpr_free(serverlist->servers[i]);
+  }
+  gpr_free(serverlist->servers);
+  gpr_free(serverlist);
+}
+
+xds_grpclb_serverlist* xds_grpclb_serverlist_copy(
+    const xds_grpclb_serverlist* sl) {
+  xds_grpclb_serverlist* copy = static_cast<xds_grpclb_serverlist*>(
+      gpr_zalloc(sizeof(xds_grpclb_serverlist)));
+  copy->num_servers = sl->num_servers;
+  copy->servers = static_cast<xds_grpclb_server**>(
+      gpr_malloc(sizeof(xds_grpclb_server*) * sl->num_servers));
+  for (size_t i = 0; i < sl->num_servers; i++) {
+    copy->servers[i] =
+        static_cast<xds_grpclb_server*>(gpr_malloc(sizeof(xds_grpclb_server)));
+    memcpy(copy->servers[i], sl->servers[i], sizeof(xds_grpclb_server));
+  }
+  return copy;
+}
+
+bool xds_grpclb_serverlist_equals(const xds_grpclb_serverlist* lhs,
+                                  const xds_grpclb_serverlist* rhs) {
+  if (lhs == nullptr || rhs == nullptr) {
+    return false;
+  }
+  if (lhs->num_servers != rhs->num_servers) {
+    return false;
+  }
+  for (size_t i = 0; i < lhs->num_servers; i++) {
+    if (!xds_grpclb_server_equals(lhs->servers[i], rhs->servers[i])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool xds_grpclb_server_equals(const xds_grpclb_server* lhs,
+                              const xds_grpclb_server* rhs) {
+  return memcmp(lhs, rhs, sizeof(xds_grpclb_server)) == 0;
+}
+
+int xds_grpclb_duration_compare(const xds_grpclb_duration* lhs,
+                                const xds_grpclb_duration* rhs) {
+  GPR_ASSERT(lhs && rhs);
+  if (lhs->has_seconds && rhs->has_seconds) {
+    if (lhs->seconds < rhs->seconds) return -1;
+    if (lhs->seconds > rhs->seconds) return 1;
+  } else if (lhs->has_seconds) {
+    return 1;
+  } else if (rhs->has_seconds) {
+    return -1;
+  }
+
+  GPR_ASSERT(lhs->seconds == rhs->seconds);
+  if (lhs->has_nanos && rhs->has_nanos) {
+    if (lhs->nanos < rhs->nanos) return -1;
+    if (lhs->nanos > rhs->nanos) return 1;
+  } else if (lhs->has_nanos) {
+    return 1;
+  } else if (rhs->has_nanos) {
+    return -1;
+  }
+
+  return 0;
+}
+
+grpc_millis xds_grpclb_duration_to_millis(xds_grpclb_duration* duration_pb) {
+  return static_cast<grpc_millis>(
+      (duration_pb->has_seconds ? duration_pb->seconds : 0) * GPR_MS_PER_SEC +
+      (duration_pb->has_nanos ? duration_pb->nanos : 0) / GPR_NS_PER_MS);
+}
+
+void xds_grpclb_initial_response_destroy(
+    xds_grpclb_initial_response* response) {
+  gpr_free(response);
+}

src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h

@@ -0,0 +1,89 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_LOAD_BALANCER_API_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_LOAD_BALANCER_API_H
+
+#include <grpc/support/port_platform.h>
+
+#include <grpc/slice_buffer.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h"
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+
+#define XDS_SERVICE_NAME_MAX_LENGTH 128
+
+typedef grpc_lb_v1_Server_ip_address_t xds_grpclb_ip_address;
+typedef grpc_lb_v1_LoadBalanceRequest xds_grpclb_request;
+typedef grpc_lb_v1_InitialLoadBalanceResponse xds_grpclb_initial_response;
+typedef grpc_lb_v1_Server xds_grpclb_server;
+typedef google_protobuf_Duration xds_grpclb_duration;
+typedef google_protobuf_Timestamp xds_grpclb_timestamp;
+
+typedef struct {
+  xds_grpclb_server** servers;
+  size_t num_servers;
+} xds_grpclb_serverlist;
+
+/** Create a request for a gRPC LB service under \a lb_service_name */
+xds_grpclb_request* xds_grpclb_request_create(const char* lb_service_name);
+xds_grpclb_request* xds_grpclb_load_report_request_create_locked(
+    grpc_core::XdsLbClientStats* client_stats);
+
+/** Protocol Buffers v3-encode \a request */
+grpc_slice xds_grpclb_request_encode(const xds_grpclb_request* request);
+
+/** Destroy \a request */
+void xds_grpclb_request_destroy(xds_grpclb_request* request);
+
+/** Parse (ie, decode) the bytes in \a encoded_xds_grpclb_response as a \a
+ * xds_grpclb_initial_response */
+xds_grpclb_initial_response* xds_grpclb_initial_response_parse(
+    grpc_slice encoded_xds_grpclb_response);
+
+/** Parse the list of servers from an encoded \a xds_grpclb_response */
+xds_grpclb_serverlist* xds_grpclb_response_parse_serverlist(
+    grpc_slice encoded_xds_grpclb_response);
+
+/** Return a copy of \a sl. The caller is responsible for calling \a
+ * xds_grpclb_destroy_serverlist on the returned copy. */
+xds_grpclb_serverlist* xds_grpclb_serverlist_copy(
+    const xds_grpclb_serverlist* sl);
+
+bool xds_grpclb_serverlist_equals(const xds_grpclb_serverlist* lhs,
+                                  const xds_grpclb_serverlist* rhs);
+
+bool xds_grpclb_server_equals(const xds_grpclb_server* lhs,
+                              const xds_grpclb_server* rhs);
+
+/** Destroy \a serverlist */
+void xds_grpclb_destroy_serverlist(xds_grpclb_serverlist* serverlist);
+
+/** Compare \a lhs against \a rhs and return 0 if \a lhs and \a rhs are equal,
+ * < 0 if \a lhs represents a duration shorter than \a rhs and > 0 otherwise */
+int xds_grpclb_duration_compare(const xds_grpclb_duration* lhs,
+                                const xds_grpclb_duration* rhs);
+
+grpc_millis xds_grpclb_duration_to_millis(xds_grpclb_duration* duration_pb);
+
+/** Destroy \a initial_response */
+void xds_grpclb_initial_response_destroy(xds_grpclb_initial_response* response);
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_LOAD_BALANCER_API_H \
+        */

src/core/ext/filters/client_channel/lb_policy_factory.h

@@ -25,7 +25,7 @@
 
 #include "src/core/ext/filters/client_channel/client_channel_factory.h"
 #include "src/core/ext/filters/client_channel/lb_policy.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 //
 // representation of an LB address

src/core/ext/filters/client_channel/parse_address.h

@@ -23,8 +23,8 @@
 
 #include <stddef.h>
 
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/iomgr/resolve_address.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 /** Populate \a resolved_addr from \a uri, whose path is expected to contain a
  * unix socket path. Returns true upon success. */

src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc

@@ -201,7 +201,7 @@ void AresDnsResolver::ShutdownLocked() {
     grpc_timer_cancel(&next_resolution_timer_);
   }
   if (pending_request_ != nullptr) {
-    grpc_cancel_ares_request(pending_request_);
+    grpc_cancel_ares_request_locked(pending_request_);
   }
   if (next_completion_ != nullptr) {
     *target_result_ = nullptr;
@@ -298,6 +298,7 @@ void AresDnsResolver::OnResolvedLocked(void* arg, grpc_error* error) {
   grpc_channel_args* result = nullptr;
   GPR_ASSERT(r->resolving_);
   r->resolving_ = false;
+  gpr_free(r->pending_request_);
   r->pending_request_ = nullptr;
   if (r->lb_addresses_ != nullptr) {
     static const char* args_to_remove[2];
@@ -473,7 +474,9 @@ void grpc_resolver_dns_ares_init() {
       GRPC_LOG_IF_ERROR("ares_library_init() failed", error);
       return;
     }
-    default_resolver = grpc_resolve_address_impl;
+    if (default_resolver == nullptr) {
+      default_resolver = grpc_resolve_address_impl;
+    }
     grpc_set_resolver_impl(&ares_resolver);
     grpc_core::ResolverRegistry::Builder::RegisterResolverFactory(
         grpc_core::UniquePtr<grpc_core::ResolverFactory>(

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc

@@ -144,12 +144,12 @@ static void grpc_ares_request_unref_locked(grpc_ares_request* r) {
 void grpc_ares_complete_request_locked(grpc_ares_request* r) {
   /* Invoke on_done callback and destroy the
      request */
+  r->ev_driver = nullptr;
   grpc_lb_addresses* lb_addrs = *(r->lb_addrs_out);
   if (lb_addrs != nullptr) {
     grpc_cares_wrapper_address_sorting_sort(lb_addrs);
   }
   GRPC_CLOSURE_SCHED(r->on_done, r->error);
-  gpr_free(r);
 }
 
 static grpc_ares_hostbyname_request* create_hostbyname_request_locked(
@@ -356,15 +356,12 @@ done:
   grpc_ares_request_unref_locked(r);
 }
 
-static grpc_ares_request*
-grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
-    const char* dns_server, const char* name, const char* default_port,
-    grpc_pollset_set* interested_parties, grpc_closure* on_done,
-    grpc_lb_addresses** addrs, bool check_grpclb, char** service_config_json,
-    grpc_combiner* combiner) {
+void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
+    grpc_ares_request* r, const char* dns_server, const char* name,
+    const char* default_port, grpc_pollset_set* interested_parties,
+    bool check_grpclb, grpc_combiner* combiner) {
   grpc_error* error = GRPC_ERROR_NONE;
   grpc_ares_hostbyname_request* hr = nullptr;
-  grpc_ares_request* r = nullptr;
   ares_channel* channel = nullptr;
   /* TODO(zyc): Enable tracing after #9603 is checked in */
   /* if (grpc_dns_trace) {
@@ -390,14 +387,6 @@ grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
     }
     port = gpr_strdup(default_port);
   }
-  r = static_cast<grpc_ares_request*>(gpr_zalloc(sizeof(grpc_ares_request)));
-  r->ev_driver = nullptr;
-  r->on_done = on_done;
-  r->lb_addrs_out = addrs;
-  r->service_config_json_out = service_config_json;
-  r->success = false;
-  r->error = GRPC_ERROR_NONE;
-  r->pending_queries = 0;
   error = grpc_ares_ev_driver_create_locked(&r->ev_driver, interested_parties,
                                             combiner, r);
   if (error != GRPC_ERROR_NONE) goto error_cleanup;
@@ -458,7 +447,7 @@ grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
                on_srv_query_done_locked, r);
     gpr_free(service_name);
   }
-  if (service_config_json != nullptr) {
+  if (r->service_config_json_out != nullptr) {
     grpc_ares_request_ref_locked(r);
     char* config_name;
     gpr_asprintf(&config_name, "_grpc_config.%s", host);
@@ -470,14 +459,12 @@ grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
   grpc_ares_request_unref_locked(r);
   gpr_free(host);
   gpr_free(port);
-  return r;
+  return;
 
 error_cleanup:
-  GRPC_CLOSURE_SCHED(on_done, error);
-  gpr_free(r);
+  GRPC_CLOSURE_SCHED(r->on_done, error);
   gpr_free(host);
   gpr_free(port);
-  return nullptr;
 }
 
 static bool inner_resolve_as_ip_literal_locked(const char* name,
@@ -536,21 +523,31 @@ static grpc_ares_request* grpc_dns_lookup_ares_locked_impl(
     grpc_pollset_set* interested_parties, grpc_closure* on_done,
     grpc_lb_addresses** addrs, bool check_grpclb, char** service_config_json,
     grpc_combiner* combiner) {
+  grpc_ares_request* r =
+      static_cast<grpc_ares_request*>(gpr_zalloc(sizeof(grpc_ares_request)));
+  r->ev_driver = nullptr;
+  r->on_done = on_done;
+  r->lb_addrs_out = addrs;
+  r->service_config_json_out = service_config_json;
+  r->success = false;
+  r->error = GRPC_ERROR_NONE;
+  r->pending_queries = 0;
   // Early out if the target is an ipv4 or ipv6 literal.
   if (resolve_as_ip_literal_locked(name, default_port, addrs)) {
     GRPC_CLOSURE_SCHED(on_done, GRPC_ERROR_NONE);
-    return nullptr;
+    return r;
   }
   // Early out if the target is localhost and we're on Windows.
   if (grpc_ares_maybe_resolve_localhost_manually_locked(name, default_port,
                                                         addrs)) {
     GRPC_CLOSURE_SCHED(on_done, GRPC_ERROR_NONE);
-    return nullptr;
+    return r;
   }
   // Look up name using c-ares lib.
-  return grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
-      dns_server, name, default_port, interested_parties, on_done, addrs,
-      check_grpclb, service_config_json, combiner);
+  grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
+      r, dns_server, name, default_port, interested_parties, check_grpclb,
+      combiner);
+  return r;
 }
 
 grpc_ares_request* (*grpc_dns_lookup_ares_locked)(
@@ -559,14 +556,16 @@ grpc_ares_request* (*grpc_dns_lookup_ares_locked)(
     grpc_lb_addresses** addrs, bool check_grpclb, char** service_config_json,
     grpc_combiner* combiner) = grpc_dns_lookup_ares_locked_impl;
 
-void grpc_cancel_ares_request(grpc_ares_request* r) {
-  if (grpc_dns_lookup_ares_locked == grpc_dns_lookup_ares_locked_impl) {
-    if (r != nullptr) {
-      grpc_ares_ev_driver_shutdown_locked(r->ev_driver);
-    }
+static void grpc_cancel_ares_request_locked_impl(grpc_ares_request* r) {
+  GPR_ASSERT(r != nullptr);
+  if (r->ev_driver != nullptr) {
+    grpc_ares_ev_driver_shutdown_locked(r->ev_driver);
   }
 }
 
+void (*grpc_cancel_ares_request_locked)(grpc_ares_request* r) =
+    grpc_cancel_ares_request_locked_impl;
+
 grpc_error* grpc_ares_init(void) {
   gpr_once_init(&g_basic_init, do_basic_init);
   gpr_mu_lock(&g_init_mu);
@@ -603,20 +602,23 @@ typedef struct grpc_resolve_address_ares_request {
   grpc_lb_addresses* lb_addrs;
   /** closure to call when the resolve_address_ares request completes */
   grpc_closure* on_resolve_address_done;
-  /** a closure wrapping on_dns_lookup_done_cb, which should be invoked when the
-      grpc_dns_lookup_ares_locked operation is done. */
-  grpc_closure on_dns_lookup_done;
+  /** a closure wrapping on_resolve_address_done, which should be invoked when
+     the grpc_dns_lookup_ares_locked operation is done. */
+  grpc_closure on_dns_lookup_done_locked;
   /* target name */
   const char* name;
   /* default port to use if none is specified */
   const char* default_port;
   /* pollset_set to be driven by */
   grpc_pollset_set* interested_parties;
+  /* underlying ares_request that the query is performed on */
+  grpc_ares_request* ares_request;
 } grpc_resolve_address_ares_request;
 
-static void on_dns_lookup_done_cb(void* arg, grpc_error* error) {
+static void on_dns_lookup_done_locked(void* arg, grpc_error* error) {
   grpc_resolve_address_ares_request* r =
       static_cast<grpc_resolve_address_ares_request*>(arg);
+  gpr_free(r->ares_request);
   grpc_resolved_addresses** resolved_addresses = r->addrs_out;
   if (r->lb_addrs == nullptr || r->lb_addrs->num_addresses == 0) {
     *resolved_addresses = nullptr;
@@ -643,9 +645,9 @@ static void grpc_resolve_address_invoke_dns_lookup_ares_locked(
     void* arg, grpc_error* unused_error) {
   grpc_resolve_address_ares_request* r =
       static_cast<grpc_resolve_address_ares_request*>(arg);
-  grpc_dns_lookup_ares_locked(
+  r->ares_request = grpc_dns_lookup_ares_locked(
       nullptr /* dns_server */, r->name, r->default_port, r->interested_parties,
-      &r->on_dns_lookup_done, &r->lb_addrs, false /* check_grpclb */,
+      &r->on_dns_lookup_done_locked, &r->lb_addrs, false /* check_grpclb */,
       nullptr /* service_config_json */, r->combiner);
 }
 
@@ -660,8 +662,8 @@ static void grpc_resolve_address_ares_impl(const char* name,
   r->combiner = grpc_combiner_create();
   r->addrs_out = addrs;
   r->on_resolve_address_done = on_done;
-  GRPC_CLOSURE_INIT(&r->on_dns_lookup_done, on_dns_lookup_done_cb, r,
-                    grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&r->on_dns_lookup_done_locked, on_dns_lookup_done_locked, r,
+                    grpc_combiner_scheduler(r->combiner));
   r->name = name;
   r->default_port = default_port;
   r->interested_parties = interested_parties;

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h

@@ -54,7 +54,8 @@ extern void (*grpc_resolve_address_ares)(const char* name,
   port in \a name. grpc_ares_init() must be called at least once before this
   function. \a on_done may be called directly in this function without being
   scheduled with \a exec_ctx, so it must not try to acquire locks that are
-  being held by the caller. */
+  being held by the caller. The returned grpc_ares_request object is owned
+  by the caller and it is safe to free after on_done is called back. */
 extern grpc_ares_request* (*grpc_dns_lookup_ares_locked)(
     const char* dns_server, const char* name, const char* default_port,
     grpc_pollset_set* interested_parties, grpc_closure* on_done,
@@ -62,7 +63,7 @@ extern grpc_ares_request* (*grpc_dns_lookup_ares_locked)(
     char** service_config_json, grpc_combiner* combiner);
 
 /* Cancel the pending grpc_ares_request \a request */
-void grpc_cancel_ares_request(grpc_ares_request* request);
+extern void (*grpc_cancel_ares_request_locked)(grpc_ares_request* request);
 
 /* Initialize gRPC ares wrapper. Must be called at least once before
    grpc_resolve_address_ares(). */

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc

@@ -40,7 +40,10 @@ grpc_ares_request* (*grpc_dns_lookup_ares_locked)(
     grpc_lb_addresses** addrs, bool check_grpclb, char** service_config_json,
     grpc_combiner* combiner) = grpc_dns_lookup_ares_locked_impl;
 
-void grpc_cancel_ares_request(grpc_ares_request* r) {}
+static void grpc_cancel_ares_request_locked_impl(grpc_ares_request* r) {}
+
+void (*grpc_cancel_ares_request_locked)(grpc_ares_request* r) =
+    grpc_cancel_ares_request_locked_impl;
 
 grpc_error* grpc_ares_init(void) { return GRPC_ERROR_NONE; }
 

src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h

@@ -20,9 +20,9 @@
 #include <grpc/support/port_platform.h>
 
 #include "src/core/ext/filters/client_channel/lb_policy_factory.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/gprpp/ref_counted.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 #define GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR \
   "grpc.fake_resolver.response_generator"

src/core/ext/filters/client_channel/resolver_factory.h

@@ -24,11 +24,11 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/resolver.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/gprpp/abstract.h"
 #include "src/core/lib/gprpp/memory.h"
 #include "src/core/lib/gprpp/orphanable.h"
 #include "src/core/lib/iomgr/pollset_set.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 namespace grpc_core {
 

src/core/ext/filters/client_channel/subchannel.cc

@@ -30,10 +30,10 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/client_channel.h"
+#include "src/core/ext/filters/client_channel/health/health_check_client.h"
 #include "src/core/ext/filters/client_channel/parse_address.h"
 #include "src/core/ext/filters/client_channel/proxy_mapper_registry.h"
 #include "src/core/ext/filters/client_channel/subchannel_index.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
@@ -41,6 +41,7 @@
 #include "src/core/lib/gpr/alloc.h"
 #include "src/core/lib/gprpp/debug_location.h"
 #include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/mutex_lock.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/timer.h"
@@ -50,7 +51,9 @@
 #include "src/core/lib/surface/channel_init.h"
 #include "src/core/lib/transport/connectivity_state.h"
 #include "src/core/lib/transport/error_utils.h"
+#include "src/core/lib/transport/service_config.h"
 #include "src/core/lib/transport/status_metadata.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 #define INTERNAL_REF_BITS 16
 #define STRONG_REF_MASK (~(gpr_atm)((1 << INTERNAL_REF_BITS) - 1))
@@ -66,6 +69,10 @@ struct state_watcher {
   grpc_closure closure;
   grpc_subchannel* subchannel;
   grpc_connectivity_state connectivity_state;
+  grpc_connectivity_state last_connectivity_state;
+  grpc_core::OrphanablePtr<grpc_core::HealthCheckClient> health_check_client;
+  grpc_closure health_check_closure;
+  grpc_connectivity_state health_state;
 };
 }  // namespace
 
@@ -78,6 +85,12 @@ typedef struct external_state_watcher {
   struct external_state_watcher* prev;
 } external_state_watcher;
 
+namespace grpc_core {
+
+class ConnectedSubchannelStateWatcher;
+
+}  // namespace grpc_core
+
 struct grpc_subchannel {
   grpc_connector* connector;
 
@@ -109,19 +122,24 @@ struct grpc_subchannel {
       being setup */
   grpc_pollset_set* pollset_set;
 
+  grpc_core::UniquePtr<char> health_check_service_name;
+
   /** mutex protecting remaining elements */
   gpr_mu mu;
 
-  /** active connection, or null; of type grpc_core::ConnectedSubchannel
-   */
+  /** active connection, or null */
   grpc_core::RefCountedPtr<grpc_core::ConnectedSubchannel> connected_subchannel;
+  grpc_core::OrphanablePtr<grpc_core::ConnectedSubchannelStateWatcher>
+      connected_subchannel_watcher;
 
   /** have we seen a disconnection? */
   bool disconnected;
   /** are we connecting */
   bool connecting;
+
   /** connectivity state tracking */
   grpc_connectivity_state_tracker state_tracker;
+  grpc_connectivity_state_tracker state_and_health_tracker;
 
   external_state_watcher root_external_state_watcher;
 
@@ -153,6 +171,171 @@ struct grpc_subchannel_call {
   grpc_millis deadline;
 };
 
+static void maybe_start_connecting_locked(grpc_subchannel* c);
+
+static const char* subchannel_connectivity_state_change_string(
+    grpc_connectivity_state state) {
+  switch (state) {
+    case GRPC_CHANNEL_IDLE:
+      return "Subchannel state change to IDLE";
+    case GRPC_CHANNEL_CONNECTING:
+      return "Subchannel state change to CONNECTING";
+    case GRPC_CHANNEL_READY:
+      return "Subchannel state change to READY";
+    case GRPC_CHANNEL_TRANSIENT_FAILURE:
+      return "Subchannel state change to TRANSIENT_FAILURE";
+    case GRPC_CHANNEL_SHUTDOWN:
+      return "Subchannel state change to SHUTDOWN";
+  }
+  GPR_UNREACHABLE_CODE(return "UNKNOWN");
+}
+
+static void set_subchannel_connectivity_state_locked(
+    grpc_subchannel* c, grpc_connectivity_state state, grpc_error* error,
+    const char* reason) {
+  if (c->channelz_subchannel != nullptr) {
+    c->channelz_subchannel->AddTraceEvent(
+        grpc_core::channelz::ChannelTrace::Severity::Info,
+        grpc_slice_from_static_string(
+            subchannel_connectivity_state_change_string(state)));
+  }
+  grpc_connectivity_state_set(&c->state_tracker, state, error, reason);
+}
+
+namespace grpc_core {
+
+class ConnectedSubchannelStateWatcher
+    : public InternallyRefCounted<ConnectedSubchannelStateWatcher> {
+ public:
+  // Must be instantiated while holding c->mu.
+  explicit ConnectedSubchannelStateWatcher(grpc_subchannel* c)
+      : subchannel_(c) {
+    // Steal subchannel ref for connecting.
+    GRPC_SUBCHANNEL_WEAK_REF(subchannel_, "state_watcher");
+    GRPC_SUBCHANNEL_WEAK_UNREF(subchannel_, "connecting");
+    // Start watching for connectivity state changes.
+    // Callback uses initial ref to this.
+    GRPC_CLOSURE_INIT(&on_connectivity_changed_, OnConnectivityChanged, this,
+                      grpc_schedule_on_exec_ctx);
+    c->connected_subchannel->NotifyOnStateChange(c->pollset_set,
+                                                 &pending_connectivity_state_,
+                                                 &on_connectivity_changed_);
+    // Start health check if needed.
+    grpc_connectivity_state health_state = GRPC_CHANNEL_READY;
+    if (c->health_check_service_name != nullptr) {
+      health_check_client_ = grpc_core::MakeOrphanable<HealthCheckClient>(
+          c->health_check_service_name.get(), c->connected_subchannel,
+          c->pollset_set, c->channelz_subchannel);
+      GRPC_CLOSURE_INIT(&on_health_changed_, OnHealthChanged, this,
+                        grpc_schedule_on_exec_ctx);
+      Ref().release();  // Ref for health callback tracked manually.
+      health_check_client_->NotifyOnHealthChange(&health_state_,
+                                                 &on_health_changed_);
+      health_state = GRPC_CHANNEL_CONNECTING;
+    }
+    // Report initial state.
+    set_subchannel_connectivity_state_locked(
+        c, GRPC_CHANNEL_READY, GRPC_ERROR_NONE, "subchannel_connected");
+    grpc_connectivity_state_set(&c->state_and_health_tracker, health_state,
+                                GRPC_ERROR_NONE, "subchannel_connected");
+  }
+
+  ~ConnectedSubchannelStateWatcher() {
+    GRPC_SUBCHANNEL_WEAK_UNREF(subchannel_, "state_watcher");
+  }
+
+  void Orphan() override { health_check_client_.reset(); }
+
+ private:
+  static void OnConnectivityChanged(void* arg, grpc_error* error) {
+    auto* self = static_cast<ConnectedSubchannelStateWatcher*>(arg);
+    grpc_subchannel* c = self->subchannel_;
+    {
+      MutexLock lock(&c->mu);
+      switch (self->pending_connectivity_state_) {
+        case GRPC_CHANNEL_TRANSIENT_FAILURE:
+        case GRPC_CHANNEL_SHUTDOWN: {
+          if (!c->disconnected && c->connected_subchannel != nullptr) {
+            if (grpc_trace_stream_refcount.enabled()) {
+              gpr_log(GPR_INFO,
+                      "Connected subchannel %p of subchannel %p has gone into "
+                      "%s. Attempting to reconnect.",
+                      c->connected_subchannel.get(), c,
+                      grpc_connectivity_state_name(
+                          self->pending_connectivity_state_));
+            }
+            c->connected_subchannel.reset();
+            c->connected_subchannel_watcher.reset();
+            self->last_connectivity_state_ = GRPC_CHANNEL_TRANSIENT_FAILURE;
+            set_subchannel_connectivity_state_locked(
+                c, GRPC_CHANNEL_TRANSIENT_FAILURE, GRPC_ERROR_REF(error),
+                "reflect_child");
+            grpc_connectivity_state_set(&c->state_and_health_tracker,
+                                        GRPC_CHANNEL_TRANSIENT_FAILURE,
+                                        GRPC_ERROR_REF(error), "reflect_child");
+            c->backoff_begun = false;
+            c->backoff->Reset();
+            maybe_start_connecting_locked(c);
+          } else {
+            self->last_connectivity_state_ = GRPC_CHANNEL_SHUTDOWN;
+          }
+          self->health_check_client_.reset();
+          break;
+        }
+        default: {
+          // In principle, this should never happen.  We should not get
+          // a callback for READY, because that was the state we started
+          // this watch from.  And a connected subchannel should never go
+          // from READY to CONNECTING or IDLE.
+          self->last_connectivity_state_ = self->pending_connectivity_state_;
+          set_subchannel_connectivity_state_locked(
+              c, self->pending_connectivity_state_, GRPC_ERROR_REF(error),
+              "reflect_child");
+          if (self->pending_connectivity_state_ != GRPC_CHANNEL_READY) {
+            grpc_connectivity_state_set(&c->state_and_health_tracker,
+                                        self->pending_connectivity_state_,
+                                        GRPC_ERROR_REF(error), "reflect_child");
+          }
+          c->connected_subchannel->NotifyOnStateChange(
+              nullptr, &self->pending_connectivity_state_,
+              &self->on_connectivity_changed_);
+          self = nullptr;  // So we don't unref below.
+        }
+      }
+    }
+    // Don't unref until we've released the lock, because this might
+    // cause the subchannel (which contains the lock) to be destroyed.
+    if (self != nullptr) self->Unref();
+  }
+
+  static void OnHealthChanged(void* arg, grpc_error* error) {
+    auto* self = static_cast<ConnectedSubchannelStateWatcher*>(arg);
+    if (self->health_state_ == GRPC_CHANNEL_SHUTDOWN) {
+      self->Unref();
+      return;
+    }
+    grpc_subchannel* c = self->subchannel_;
+    MutexLock lock(&c->mu);
+    if (self->last_connectivity_state_ == GRPC_CHANNEL_READY) {
+      grpc_connectivity_state_set(&c->state_and_health_tracker,
+                                  self->health_state_, GRPC_ERROR_REF(error),
+                                  "health_changed");
+    }
+    self->health_check_client_->NotifyOnHealthChange(&self->health_state_,
+                                                     &self->on_health_changed_);
+  }
+
+  grpc_subchannel* subchannel_;
+  grpc_closure on_connectivity_changed_;
+  grpc_connectivity_state pending_connectivity_state_ = GRPC_CHANNEL_READY;
+  grpc_connectivity_state last_connectivity_state_ = GRPC_CHANNEL_READY;
+  grpc_core::OrphanablePtr<grpc_core::HealthCheckClient> health_check_client_;
+  grpc_closure on_health_changed_;
+  grpc_connectivity_state health_state_ = GRPC_CHANNEL_CONNECTING;
+};
+
+}  // namespace grpc_core
+
 #define SUBCHANNEL_CALL_TO_CALL_STACK(call)                          \
   (grpc_call_stack*)((char*)(call) + GPR_ROUND_UP_TO_ALIGNMENT_SIZE( \
                                          sizeof(grpc_subchannel_call)))
@@ -198,8 +381,10 @@ static void subchannel_destroy(void* arg, grpc_error* error) {
     c->channelz_subchannel.reset();
   }
   gpr_free((void*)c->filters);
+  c->health_check_service_name.reset();
   grpc_channel_args_destroy(c->args);
   grpc_connectivity_state_destroy(&c->state_tracker);
+  grpc_connectivity_state_destroy(&c->state_and_health_tracker);
   grpc_connector_unref(c->connector);
   grpc_pollset_set_destroy(c->pollset_set);
   grpc_subchannel_key_destroy(c->key);
@@ -262,6 +447,7 @@ static void disconnect(grpc_subchannel* c) {
   grpc_connector_shutdown(c->connector, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                                             "Subchannel disconnected"));
   c->connected_subchannel.reset();
+  c->connected_subchannel_watcher.reset();
   gpr_mu_unlock(&c->mu);
 }
 
@@ -337,6 +523,31 @@ static void parse_args_for_backoff_values(
       .set_max_backoff(max_backoff_ms);
 }
 
+namespace grpc_core {
+namespace {
+
+struct HealthCheckParams {
+  UniquePtr<char> service_name;
+
+  static void Parse(const grpc_json* field, HealthCheckParams* params) {
+    if (strcmp(field->key, "healthCheckConfig") == 0) {
+      if (field->type != GRPC_JSON_OBJECT) return;
+      for (grpc_json* sub_field = field->child; sub_field != nullptr;
+           sub_field = sub_field->next) {
+        if (sub_field->key == nullptr) return;
+        if (strcmp(sub_field->key, "serviceName") == 0) {
+          if (params->service_name != nullptr) return;  // Duplicate.
+          if (sub_field->type != GRPC_JSON_STRING) return;
+          params->service_name.reset(gpr_strdup(sub_field->value));
+        }
+      }
+    }
+  }
+};
+
+}  // namespace
+}  // namespace grpc_core
+
 grpc_subchannel* grpc_subchannel_create(grpc_connector* connector,
                                         const grpc_subchannel_args* args) {
   grpc_subchannel_key* key = grpc_subchannel_key_create(args);
@@ -387,12 +598,28 @@ grpc_subchannel* grpc_subchannel_create(grpc_connector* connector,
                     grpc_schedule_on_exec_ctx);
   grpc_connectivity_state_init(&c->state_tracker, GRPC_CHANNEL_IDLE,
                                "subchannel");
+  grpc_connectivity_state_init(&c->state_and_health_tracker, GRPC_CHANNEL_IDLE,
+                               "subchannel");
   grpc_core::BackOff::Options backoff_options;
   parse_args_for_backoff_values(args->args, &backoff_options,
                                 &c->min_connect_timeout_ms);
   c->backoff.Init(backoff_options);
   gpr_mu_init(&c->mu);
 
+  // Check whether we should enable health checking.
+  const char* service_config_json = grpc_channel_arg_get_string(
+      grpc_channel_args_find(c->args, GRPC_ARG_SERVICE_CONFIG));
+  if (service_config_json != nullptr) {
+    grpc_core::UniquePtr<grpc_core::ServiceConfig> service_config =
+        grpc_core::ServiceConfig::Create(service_config_json);
+    if (service_config != nullptr) {
+      grpc_core::HealthCheckParams params;
+      service_config->ParseGlobalParams(grpc_core::HealthCheckParams::Parse,
+                                        &params);
+      c->health_check_service_name = std::move(params.service_name);
+    }
+  }
+
   const grpc_arg* arg =
       grpc_channel_args_find(c->args, GRPC_ARG_ENABLE_CHANNELZ);
   bool channelz_enabled =
@@ -436,17 +663,21 @@ static void continue_connect_locked(grpc_subchannel* c) {
   c->next_attempt_deadline = c->backoff->NextAttemptTime();
   args.deadline = std::max(c->next_attempt_deadline, min_deadline);
   args.channel_args = c->args;
-  grpc_connectivity_state_set(&c->state_tracker, GRPC_CHANNEL_CONNECTING,
-                              GRPC_ERROR_NONE, "connecting");
+  set_subchannel_connectivity_state_locked(c, GRPC_CHANNEL_CONNECTING,
+                                           GRPC_ERROR_NONE, "connecting");
+  grpc_connectivity_state_set(&c->state_and_health_tracker,
+                              GRPC_CHANNEL_CONNECTING, GRPC_ERROR_NONE,
+                              "connecting");
   grpc_connector_connect(c->connector, &args, &c->connecting_result,
                          &c->on_connected);
 }
 
-grpc_connectivity_state grpc_subchannel_check_connectivity(grpc_subchannel* c,
-                                                           grpc_error** error) {
-  grpc_connectivity_state state;
+grpc_connectivity_state grpc_subchannel_check_connectivity(
+    grpc_subchannel* c, grpc_error** error, bool inhibit_health_checks) {
   gpr_mu_lock(&c->mu);
-  state = grpc_connectivity_state_get(&c->state_tracker, error);
+  grpc_connectivity_state_tracker* tracker =
+      inhibit_health_checks ? &c->state_tracker : &c->state_and_health_tracker;
+  grpc_connectivity_state state = grpc_connectivity_state_get(tracker, error);
   gpr_mu_unlock(&c->mu);
   return state;
 }
@@ -504,7 +735,8 @@ static void maybe_start_connecting_locked(grpc_subchannel* c) {
     /* Already connected: don't restart */
     return;
   }
-  if (!grpc_connectivity_state_has_watchers(&c->state_tracker)) {
+  if (!grpc_connectivity_state_has_watchers(&c->state_tracker) &&
+      !grpc_connectivity_state_has_watchers(&c->state_and_health_tracker)) {
     /* Nobody is interested in connecting: so don't just yet */
     return;
   }
@@ -531,16 +763,18 @@ static void maybe_start_connecting_locked(grpc_subchannel* c) {
 
 void grpc_subchannel_notify_on_state_change(
     grpc_subchannel* c, grpc_pollset_set* interested_parties,
-    grpc_connectivity_state* state, grpc_closure* notify) {
+    grpc_connectivity_state* state, grpc_closure* notify,
+    bool inhibit_health_checks) {
+  grpc_connectivity_state_tracker* tracker =
+      inhibit_health_checks ? &c->state_tracker : &c->state_and_health_tracker;
   external_state_watcher* w;
-
   if (state == nullptr) {
     gpr_mu_lock(&c->mu);
     for (w = c->root_external_state_watcher.next;
          w != &c->root_external_state_watcher; w = w->next) {
       if (w->notify == notify) {
-        grpc_connectivity_state_notify_on_state_change(&c->state_tracker,
-                                                       nullptr, &w->closure);
+        grpc_connectivity_state_notify_on_state_change(tracker, nullptr,
+                                                       &w->closure);
       }
     }
     gpr_mu_unlock(&c->mu);
@@ -559,62 +793,12 @@ void grpc_subchannel_notify_on_state_change(
     w->next = &c->root_external_state_watcher;
     w->prev = w->next->prev;
     w->next->prev = w->prev->next = w;
-    grpc_connectivity_state_notify_on_state_change(&c->state_tracker, state,
-                                                   &w->closure);
+    grpc_connectivity_state_notify_on_state_change(tracker, state, &w->closure);
     maybe_start_connecting_locked(c);
     gpr_mu_unlock(&c->mu);
   }
 }
 
-static void on_connected_subchannel_connectivity_changed(void* p,
-                                                         grpc_error* error) {
-  state_watcher* connected_subchannel_watcher = static_cast<state_watcher*>(p);
-  grpc_subchannel* c = connected_subchannel_watcher->subchannel;
-  gpr_mu* mu = &c->mu;
-
-  gpr_mu_lock(mu);
-
-  switch (connected_subchannel_watcher->connectivity_state) {
-    case GRPC_CHANNEL_TRANSIENT_FAILURE:
-    case GRPC_CHANNEL_SHUTDOWN: {
-      if (!c->disconnected && c->connected_subchannel != nullptr) {
-        if (grpc_trace_stream_refcount.enabled()) {
-          gpr_log(GPR_INFO,
-                  "Connected subchannel %p of subchannel %p has gone into %s. "
-                  "Attempting to reconnect.",
-                  c->connected_subchannel.get(), c,
-                  grpc_connectivity_state_name(
-                      connected_subchannel_watcher->connectivity_state));
-        }
-        c->connected_subchannel.reset();
-        grpc_connectivity_state_set(&c->state_tracker,
-                                    GRPC_CHANNEL_TRANSIENT_FAILURE,
-                                    GRPC_ERROR_REF(error), "reflect_child");
-        c->backoff_begun = false;
-        c->backoff->Reset();
-        maybe_start_connecting_locked(c);
-      } else {
-        connected_subchannel_watcher->connectivity_state =
-            GRPC_CHANNEL_SHUTDOWN;
-      }
-      break;
-    }
-    default: {
-      grpc_connectivity_state_set(
-          &c->state_tracker, connected_subchannel_watcher->connectivity_state,
-          GRPC_ERROR_REF(error), "reflect_child");
-      GRPC_SUBCHANNEL_WEAK_REF(c, "state_watcher");
-      c->connected_subchannel->NotifyOnStateChange(
-          nullptr, &connected_subchannel_watcher->connectivity_state,
-          &connected_subchannel_watcher->closure);
-      connected_subchannel_watcher = nullptr;
-    }
-  }
-  gpr_mu_unlock(mu);
-  GRPC_SUBCHANNEL_WEAK_UNREF(c, "state_watcher");
-  gpr_free(connected_subchannel_watcher);
-}
-
 static bool publish_transport_locked(grpc_subchannel* c) {
   /* construct channel stack */
   grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
@@ -641,17 +825,7 @@ static bool publish_transport_locked(grpc_subchannel* c) {
   intptr_t socket_uuid = c->connecting_result.socket_uuid;
   memset(&c->connecting_result, 0, sizeof(c->connecting_result));
 
-  /* initialize state watcher */
-  state_watcher* connected_subchannel_watcher = static_cast<state_watcher*>(
-      gpr_zalloc(sizeof(*connected_subchannel_watcher)));
-  connected_subchannel_watcher->subchannel = c;
-  connected_subchannel_watcher->connectivity_state = GRPC_CHANNEL_READY;
-  GRPC_CLOSURE_INIT(&connected_subchannel_watcher->closure,
-                    on_connected_subchannel_connectivity_changed,
-                    connected_subchannel_watcher, grpc_schedule_on_exec_ctx);
-
   if (c->disconnected) {
-    gpr_free(connected_subchannel_watcher);
     grpc_channel_stack_destroy(stk);
     gpr_free(stk);
     return false;
@@ -663,17 +837,10 @@ static bool publish_transport_locked(grpc_subchannel* c) {
   gpr_log(GPR_INFO, "New connected subchannel at %p for subchannel %p",
           c->connected_subchannel.get(), c);
 
-  /* setup subchannel watching connected subchannel for changes; subchannel
-     ref for connecting is donated to the state watcher */
-  GRPC_SUBCHANNEL_WEAK_REF(c, "state_watcher");
-  GRPC_SUBCHANNEL_WEAK_UNREF(c, "connecting");
-  c->connected_subchannel->NotifyOnStateChange(
-      c->pollset_set, &connected_subchannel_watcher->connectivity_state,
-      &connected_subchannel_watcher->closure);
-
-  /* signal completion */
-  grpc_connectivity_state_set(&c->state_tracker, GRPC_CHANNEL_READY,
-                              GRPC_ERROR_NONE, "connected");
+  // Instantiate state watcher.  Will clean itself up.
+  c->connected_subchannel_watcher =
+      grpc_core::MakeOrphanable<grpc_core::ConnectedSubchannelStateWatcher>(c);
+
   return true;
 }
 
@@ -690,8 +857,14 @@ static void on_subchannel_connected(void* arg, grpc_error* error) {
   } else if (c->disconnected) {
     GRPC_SUBCHANNEL_WEAK_UNREF(c, "connecting");
   } else {
+    set_subchannel_connectivity_state_locked(
+        c, GRPC_CHANNEL_TRANSIENT_FAILURE,
+        grpc_error_set_int(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+                               "Connect Failed", &error, 1),
+                           GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE),
+        "connect_failed");
     grpc_connectivity_state_set(
-        &c->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE,
+        &c->state_and_health_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE,
         grpc_error_set_int(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
                                "Connect Failed", &error, 1),
                            GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE),
@@ -760,9 +933,12 @@ static void get_call_status(grpc_subchannel_call* call,
     grpc_error_get_status(error, call->deadline, status, nullptr, nullptr,
                           nullptr);
   } else {
-    GPR_ASSERT(md_batch->idx.named.grpc_status != nullptr);
-    *status =
-        grpc_get_status_code_from_metadata(md_batch->idx.named.grpc_status->md);
+    if (md_batch->idx.named.grpc_status != nullptr) {
+      *status = grpc_get_status_code_from_metadata(
+          md_batch->idx.named.grpc_status->md);
+    } else {
+      *status = GRPC_STATUS_UNKNOWN;
+    }
   }
   GRPC_ERROR_UNREF(error);
 }
@@ -924,15 +1100,8 @@ void ConnectedSubchannel::Ping(grpc_closure* on_initiate,
 
 grpc_error* ConnectedSubchannel::CreateCall(const CallArgs& args,
                                             grpc_subchannel_call** call) {
-  size_t allocation_size =
-      GPR_ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(grpc_subchannel_call));
-  if (args.parent_data_size > 0) {
-    allocation_size +=
-        GPR_ROUND_UP_TO_ALIGNMENT_SIZE(channel_stack_->call_stack_size) +
-        args.parent_data_size;
-  } else {
-    allocation_size += channel_stack_->call_stack_size;
-  }
+  const size_t allocation_size =
+      GetInitialCallSizeEstimate(args.parent_data_size);
   *call = static_cast<grpc_subchannel_call*>(
       gpr_arena_alloc(args.arena, allocation_size));
   grpc_call_stack* callstk = SUBCHANNEL_CALL_TO_CALL_STACK(*call);
@@ -962,4 +1131,18 @@ grpc_error* ConnectedSubchannel::CreateCall(const CallArgs& args,
   return GRPC_ERROR_NONE;
 }
 
+size_t ConnectedSubchannel::GetInitialCallSizeEstimate(
+    size_t parent_data_size) const {
+  size_t allocation_size =
+      GPR_ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(grpc_subchannel_call));
+  if (parent_data_size > 0) {
+    allocation_size +=
+        GPR_ROUND_UP_TO_ALIGNMENT_SIZE(channel_stack_->call_stack_size) +
+        parent_data_size;
+  } else {
+    allocation_size += channel_stack_->call_stack_size;
+  }
+  return allocation_size;
+}
+
 }  // namespace grpc_core

src/core/ext/filters/client_channel/subchannel.h

@@ -103,6 +103,8 @@ class ConnectedSubchannel : public RefCountedWithTracing<ConnectedSubchannel> {
   }
   intptr_t socket_uuid() { return socket_uuid_; }
 
+  size_t GetInitialCallSizeEstimate(size_t parent_data_size) const;
+
  private:
   grpc_channel_stack* channel_stack_;
   // ref counted pointer to the channelz node in this connected subchannel's
@@ -143,13 +145,14 @@ void* grpc_connected_subchannel_call_get_parent_data(
 
 /** poll the current connectivity state of a channel */
 grpc_connectivity_state grpc_subchannel_check_connectivity(
-    grpc_subchannel* channel, grpc_error** error);
+    grpc_subchannel* channel, grpc_error** error, bool inhibit_health_checking);
 
 /** Calls notify when the connectivity state of a channel becomes different
     from *state.  Updates *state with the new state of the channel. */
 void grpc_subchannel_notify_on_state_change(
     grpc_subchannel* channel, grpc_pollset_set* interested_parties,
-    grpc_connectivity_state* state, grpc_closure* notify);
+    grpc_connectivity_state* state, grpc_closure* notify,
+    bool inhibit_health_checks);
 
 /** retrieve the grpc_core::ConnectedSubchannel - or nullptr if not connected
  * (which may happen before it initially connects or during transient failures)

src/core/ext/filters/http/client_authority_filter.cc

@@ -59,9 +59,8 @@ void authority_start_transport_stream_op_batch(
       initial_metadata->idx.named.authority == nullptr) {
     grpc_error* error = grpc_metadata_batch_add_head(
         initial_metadata, &calld->authority_storage,
-        grpc_mdelem_from_slices(
-            GRPC_MDSTR_AUTHORITY,
-            grpc_slice_ref_internal(chand->default_authority)));
+        grpc_mdelem_create(GRPC_MDSTR_AUTHORITY, chand->default_authority,
+                           nullptr));
     if (error != GRPC_ERROR_NONE) {
       grpc_transport_stream_op_batch_finish_with_failure(batch, error,
                                                          calld->call_combiner);

src/core/ext/filters/load_reporting/server_load_reporting_filter.cc

@@ -25,7 +25,6 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/parse_address.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/ext/filters/load_reporting/registered_opencensus_objects.h"
 #include "src/core/ext/filters/load_reporting/server_load_reporting_filter.h"
 #include "src/core/lib/channel/channel_args.h"
@@ -36,6 +35,7 @@
 #include "src/core/lib/security/context/security_context.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/call.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 namespace grpc {
 

src/core/ext/transport/chttp2/client/chttp2_connector.cc

@@ -163,9 +163,8 @@ static void start_handshake_locked(chttp2_connector* c) {
                        c->args.interested_parties, c->handshake_mgr);
   grpc_endpoint_add_to_pollset_set(c->endpoint, c->args.interested_parties);
   grpc_handshake_manager_do_handshake(
-      c->handshake_mgr, c->args.interested_parties, c->endpoint,
-      c->args.channel_args, c->args.deadline, nullptr /* acceptor */,
-      on_handshake_done, c);
+      c->handshake_mgr, c->endpoint, c->args.channel_args, c->args.deadline,
+      nullptr /* acceptor */, on_handshake_done, c);
   c->endpoint = nullptr;  // Endpoint handed off to handshake manager.
 }
 
@@ -213,9 +212,17 @@ static void chttp2_connector_connect(grpc_connector* con,
   GRPC_CLOSURE_INIT(&c->connected, connected, c, grpc_schedule_on_exec_ctx);
   GPR_ASSERT(!c->connecting);
   c->connecting = true;
-  grpc_tcp_client_connect(&c->connected, &c->endpoint, args->interested_parties,
-                          args->channel_args, &addr, args->deadline);
+  grpc_closure* closure = &c->connected;
+  grpc_endpoint** ep = &c->endpoint;
   gpr_mu_unlock(&c->mu);
+  // In some implementations, the closure can be flushed before
+  // grpc_tcp_client_connect and since the closure requires access to c->mu,
+  // this can result in a deadlock. Refer
+  // https://github.com/grpc/grpc/issues/16427
+  // grpc_tcp_client_connect would fill c->endpoint with proper contents and we
+  // make sure that we would still exist at that point by taking a ref.
+  grpc_tcp_client_connect(closure, ep, args->interested_parties,
+                          args->channel_args, &addr, args->deadline);
 }
 
 static const grpc_connector_vtable chttp2_connector_vtable = {

src/core/ext/transport/chttp2/client/secure/secure_channel_create.cc

@@ -27,7 +27,6 @@
 
 #include "src/core/ext/filters/client_channel/client_channel.h"
 #include "src/core/ext/filters/client_channel/resolver_registry.h"
-#include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/ext/transport/chttp2/client/chttp2_connector.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/gprpp/memory.h"
@@ -39,6 +38,7 @@
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/channel.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 static void client_channel_factory_ref(
     grpc_client_channel_factory* cc_factory) {}

src/core/ext/transport/chttp2/server/chttp2_server.cc

@@ -37,8 +37,10 @@
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
 #include "src/core/lib/channel/handshaker_registry.h"
+#include "src/core/lib/gpr/host_port.h"
 #include "src/core/lib/iomgr/endpoint.h"
 #include "src/core/lib/iomgr/resolve_address.h"
+#include "src/core/lib/iomgr/resource_quota.h"
 #include "src/core/lib/iomgr/tcp_server.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
@@ -114,9 +116,16 @@ static void on_handshake_done(void* arg, grpc_error* error) {
   server_connection_state* connection_state =
       static_cast<server_connection_state*>(args->user_data);
   gpr_mu_lock(&connection_state->svr_state->mu);
+  grpc_resource_user* resource_user = grpc_server_get_default_resource_user(
+      connection_state->svr_state->server);
   if (error != GRPC_ERROR_NONE || connection_state->svr_state->shutdown) {
     const char* error_str = grpc_error_string(error);
     gpr_log(GPR_DEBUG, "Handshaking failed: %s", error_str);
+    grpc_resource_user* resource_user = grpc_server_get_default_resource_user(
+        connection_state->svr_state->server);
+    if (resource_user != nullptr) {
+      grpc_resource_user_free(resource_user, GRPC_RESOURCE_QUOTA_CHANNEL_SIZE);
+    }
     if (error == GRPC_ERROR_NONE && args->endpoint != nullptr) {
       // We were shut down after handshaking completed successfully, so
       // destroy the endpoint here.
@@ -135,12 +144,12 @@ static void on_handshake_done(void* arg, grpc_error* error) {
     // handshaker may have handed off the connection to some external
     // code, so we can just clean up here without creating a transport.
     if (args->endpoint != nullptr) {
-      grpc_transport* transport =
-          grpc_create_chttp2_transport(args->args, args->endpoint, false);
+      grpc_transport* transport = grpc_create_chttp2_transport(
+          args->args, args->endpoint, false, resource_user);
       grpc_server_setup_transport(
           connection_state->svr_state->server, transport,
           connection_state->accepting_pollset, args->args,
-          grpc_chttp2_transport_get_socket_uuid(transport));
+          grpc_chttp2_transport_get_socket_uuid(transport), resource_user);
       // Use notify_on_receive_settings callback to enforce the
       // handshake deadline.
       connection_state->transport =
@@ -159,6 +168,11 @@ static void on_handshake_done(void* arg, grpc_error* error) {
                         connection_state, grpc_schedule_on_exec_ctx);
       grpc_timer_init(&connection_state->timer, connection_state->deadline,
                       &connection_state->on_timeout);
+    } else {
+      if (resource_user != nullptr) {
+        grpc_resource_user_free(resource_user,
+                                GRPC_RESOURCE_QUOTA_CHANNEL_SIZE);
+      }
     }
   }
   grpc_handshake_manager_pending_list_remove(
@@ -183,6 +197,20 @@ static void on_accept(void* arg, grpc_endpoint* tcp,
     gpr_free(acceptor);
     return;
   }
+  grpc_resource_user* resource_user =
+      grpc_server_get_default_resource_user(state->server);
+  if (resource_user != nullptr &&
+      !grpc_resource_user_safe_alloc(resource_user,
+                                     GRPC_RESOURCE_QUOTA_CHANNEL_SIZE)) {
+    gpr_log(
+        GPR_ERROR,
+        "Memory quota exhausted, rejecting the connection, no handshaking.");
+    gpr_mu_unlock(&state->mu);
+    grpc_endpoint_shutdown(tcp, GRPC_ERROR_NONE);
+    grpc_endpoint_destroy(tcp);
+    gpr_free(acceptor);
+    return;
+  }
   grpc_handshake_manager* handshake_mgr = grpc_handshake_manager_create();
   grpc_handshake_manager_pending_list_add(&state->pending_handshake_mgrs,
                                           handshake_mgr);
@@ -208,10 +236,10 @@ static void on_accept(void* arg, grpc_endpoint* tcp,
       grpc_core::ExecCtx::Get()->Now() +
       grpc_channel_arg_get_integer(timeout_arg,
                                    {120 * GPR_MS_PER_SEC, 1, INT_MAX});
-  grpc_handshake_manager_do_handshake(
-      connection_state->handshake_mgr, nullptr /* interested_parties */, tcp,
-      state->args, connection_state->deadline, acceptor, on_handshake_done,
-      connection_state);
+  grpc_handshake_manager_do_handshake(connection_state->handshake_mgr, tcp,
+                                      state->args, connection_state->deadline,
+                                      acceptor, on_handshake_done,
+                                      connection_state);
 }
 
 /* Server callback: start listening on our ports */
@@ -340,7 +368,8 @@ grpc_error* grpc_chttp2_server_add_port(grpc_server* server, const char* addr,
   arg = grpc_channel_args_find(args, GRPC_ARG_ENABLE_CHANNELZ);
   if (grpc_channel_arg_get_bool(arg, false)) {
     state->channelz_listen_socket =
-        grpc_core::MakeRefCounted<grpc_core::channelz::ListenSocketNode>();
+        grpc_core::MakeRefCounted<grpc_core::channelz::ListenSocketNode>(
+            grpc_core::UniquePtr<char>(gpr_strdup(addr)));
     socket_uuid = state->channelz_listen_socket->uuid();
   }
 

src/core/ext/transport/chttp2/transport/chttp2_transport.cc

@@ -53,6 +53,7 @@
 #include "src/core/lib/transport/timeout_encoding.h"
 #include "src/core/lib/transport/transport.h"
 #include "src/core/lib/transport/transport_impl.h"
+#include "src/core/lib/uri/uri_parser.h"
 
 #define DEFAULT_CONNECTION_WINDOW_TARGET (1024 * 1024)
 #define MAX_WINDOW 0x7fffffffu
@@ -395,8 +396,12 @@ static bool read_channel_args(grpc_chttp2_transport* t,
     }
   }
   if (channelz_enabled) {
+    // TODO(ncteisen): add an API to endpoint to query for local addr, and pass
+    // it in here, so SocketNode knows its own address.
     t->channelz_socket =
-        grpc_core::MakeRefCounted<grpc_core::channelz::SocketNode>();
+        grpc_core::MakeRefCounted<grpc_core::channelz::SocketNode>(
+            grpc_core::UniquePtr<char>(),
+            grpc_core::UniquePtr<char>(gpr_strdup(t->peer_string)));
   }
   return enable_bdp;
 }
@@ -478,7 +483,8 @@ static void init_keepalive_pings_if_enabled(grpc_chttp2_transport* t) {
 
 static void init_transport(grpc_chttp2_transport* t,
                            const grpc_channel_args* channel_args,
-                           grpc_endpoint* ep, bool is_client) {
+                           grpc_endpoint* ep, bool is_client,
+                           grpc_resource_user* resource_user) {
   GPR_ASSERT(strlen(GRPC_CHTTP2_CLIENT_CONNECT_STRING) ==
              GRPC_CHTTP2_CLIENT_CONNECT_STRLEN);
 
@@ -491,6 +497,7 @@ static void init_transport(grpc_chttp2_transport* t,
   t->endpoint_reading = 1;
   t->next_stream_id = is_client ? 1 : 2;
   t->is_client = is_client;
+  t->resource_user = resource_user;
   t->deframe_state = is_client ? GRPC_DTS_FH_0 : GRPC_DTS_CLIENT_PREFIX_0;
   t->is_first_frame = true;
   grpc_connectivity_state_init(
@@ -778,6 +785,10 @@ static void destroy_stream_locked(void* sp, grpc_error* error) {
 
   s->flow_control.Destroy();
 
+  if (t->resource_user != nullptr) {
+    grpc_resource_user_free(t->resource_user, GRPC_RESOURCE_QUOTA_CALL_SIZE);
+  }
+
   GRPC_CHTTP2_UNREF_TRANSPORT(t, "stream");
 
   GRPC_CLOSURE_SCHED(s->destroy_stream_arg, GRPC_ERROR_NONE);
@@ -816,7 +827,21 @@ grpc_chttp2_stream* grpc_chttp2_parsing_accept_stream(grpc_chttp2_transport* t,
   if (t->channel_callback.accept_stream == nullptr) {
     return nullptr;
   }
-  grpc_chttp2_stream* accepting;
+  // Don't accept the stream if memory quota doesn't allow. Note that we should
+  // simply refuse the stream here instead of canceling the stream after it's
+  // accepted since the latter will create the call which costs much memory.
+  if (t->resource_user != nullptr &&
+      !grpc_resource_user_safe_alloc(t->resource_user,
+                                     GRPC_RESOURCE_QUOTA_CALL_SIZE)) {
+    gpr_log(GPR_ERROR, "Memory exhausted, rejecting the stream.");
+    grpc_slice_buffer_add(
+        &t->qbuf,
+        grpc_chttp2_rst_stream_create(
+            id, static_cast<uint32_t>(GRPC_HTTP2_REFUSED_STREAM), nullptr));
+    grpc_chttp2_initiate_write(t, GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM);
+    return nullptr;
+  }
+  grpc_chttp2_stream* accepting = nullptr;
   GPR_ASSERT(t->accepting_stream == nullptr);
   t->accepting_stream = &accepting;
   t->channel_callback.accept_stream(t->channel_callback.accept_stream_user_data,
@@ -2128,8 +2153,7 @@ void grpc_chttp2_fake_status(grpc_chttp2_transport* t, grpc_chttp2_stream* s,
           "add_status_message",
           grpc_chttp2_incoming_metadata_buffer_replace_or_add(
               &s->metadata_buffer[1],
-              grpc_mdelem_from_slices(GRPC_MDSTR_GRPC_MESSAGE,
-                                      grpc_slice_ref_internal(slice))));
+              grpc_mdelem_create(GRPC_MDSTR_GRPC_MESSAGE, slice, nullptr)));
     }
     s->published_metadata[1] = GRPC_METADATA_SYNTHESIZED_FROM_FAKE;
     grpc_chttp2_maybe_complete_recv_trailing_metadata(t, s);
@@ -3186,10 +3210,11 @@ intptr_t grpc_chttp2_transport_get_socket_uuid(grpc_transport* transport) {
 }
 
 grpc_transport* grpc_create_chttp2_transport(
-    const grpc_channel_args* channel_args, grpc_endpoint* ep, bool is_client) {
+    const grpc_channel_args* channel_args, grpc_endpoint* ep, bool is_client,
+    grpc_resource_user* resource_user) {
   grpc_chttp2_transport* t = static_cast<grpc_chttp2_transport*>(
       gpr_zalloc(sizeof(grpc_chttp2_transport)));
-  init_transport(t, channel_args, ep, is_client);
+  init_transport(t, channel_args, ep, is_client, resource_user);
   return &t->base;
 }
 

src/core/ext/transport/chttp2/transport/chttp2_transport.h

@@ -32,7 +32,8 @@ extern grpc_core::DebugOnlyTraceFlag grpc_trace_chttp2_refcount;
 extern bool g_flow_control_enabled;
 
 grpc_transport* grpc_create_chttp2_transport(
-    const grpc_channel_args* channel_args, grpc_endpoint* ep, bool is_client);
+    const grpc_channel_args* channel_args, grpc_endpoint* ep, bool is_client,
+    grpc_resource_user* resource_user = nullptr);
 
 intptr_t grpc_chttp2_transport_get_socket_uuid(grpc_transport* transport);
 

src/core/ext/transport/chttp2/transport/frame_rst_stream.cc

@@ -32,7 +32,7 @@ grpc_slice grpc_chttp2_rst_stream_create(uint32_t id, uint32_t code,
                                          grpc_transport_one_way_stats* stats) {
   static const size_t frame_size = 13;
   grpc_slice slice = GRPC_SLICE_MALLOC(frame_size);
-  stats->framing_bytes += frame_size;
+  if (stats != nullptr) stats->framing_bytes += frame_size;
   uint8_t* p = GRPC_SLICE_START_PTR(slice);
 
   // Frame size.

src/core/ext/transport/chttp2/transport/internal.h

@@ -285,6 +285,8 @@ struct grpc_chttp2_transport {
   grpc_endpoint* ep;
   char* peer_string;
 
+  grpc_resource_user* resource_user;
+
   grpc_combiner* combiner;
 
   grpc_closure* notify_on_receive_settings;