Merge branch 'master' into darwin-zlib-implicit-declaration

.bazelignore

@@ -7,6 +7,10 @@ libs
 objs
 third_party/abseil-cpp
 third_party/bloaty
+third_party/boringssl-with-bazel
 third_party/googleapis
+third_party/googletest
+third_party/protobuf
 third_party/protoc-gen-validate
 third_party/udpa
+third_party/upb

.github/ISSUE_TEMPLATE/bug_report.md

@@ -2,7 +2,7 @@
 name: Report a bug
 about: Create a report to help us improve
 labels: kind/bug, priority/P2
-assignees: nicolasnoble
+assignees: donnadionne
 
 ---
 

.github/ISSUE_TEMPLATE/cleanup_request.md

@@ -2,7 +2,7 @@
 name: Request a cleanup
 about: Suggest a cleanup in our repository
 labels: kind/internal cleanup, priority/P2
-assignees: nicolasnoble
+assignees: donnadionne
 
 ---
 

.github/ISSUE_TEMPLATE/feature_request.md

@@ -2,7 +2,7 @@
 name: Request a feature
 about: Suggest an idea for this project
 labels: kind/enhancement, priority/P2
-assignees: nicolasnoble
+assignees: donnadionne
 
 ---
 

.github/ISSUE_TEMPLATE/question.md

@@ -2,7 +2,7 @@
 name: Ask a question
 about: Ask a question
 labels: kind/question, priority/P3
-assignees: nicolasnoble
+assignees: donnadionne
 
 ---
 

.github/pull_request_template.md

@@ -8,4 +8,4 @@ If you know who should review your pull request, please remove the mentioning be
 
 -->
 
-@nicolasnoble
+@donnadionne

BUILD

@@ -80,11 +80,11 @@ config_setting(
 python_config_settings()
 
 # This should be updated along with build_handwritten.yaml
-g_stands_for = "gecko"
+g_stands_for = "gummybear"
 
-core_version = "14.0.0"
+core_version = "15.0.0"
 
-version = "1.35.0-dev"
+version = "1.36.0-dev"
 
 GPR_PUBLIC_HDRS = [
     "include/grpc/support/alloc.h",
@@ -323,10 +323,11 @@ grpc_cc_library(
         "grpc_no_xds": [],
         "//conditions:default": [
             "grpc_lb_policy_cds",
-            "grpc_lb_policy_eds",
             "grpc_lb_policy_xds_cluster_impl",
             "grpc_lb_policy_xds_cluster_manager",
+            "grpc_lb_policy_xds_cluster_resolver",
             "grpc_resolver_xds",
+            "grpc_xds_server_config_fetcher",
         ],
     },
     standalone = True,
@@ -377,7 +378,8 @@ grpc_cc_library(
     select_deps = {
         "grpc_no_xds": [],
         "//conditions:default": [
-            "grpc++_xds_credentials",
+            "grpc++_xds_client",
+            "grpc++_xds_server",
         ],
     },
     standalone = True,
@@ -393,16 +395,31 @@ grpc_cc_library(
 )
 
 grpc_cc_library(
-    name = "grpc++_xds_credentials",
+    name = "grpc++_xds_client",
     srcs = [
         "src/cpp/client/xds_credentials.cc",
-        "src/cpp/server/xds_server_credentials.cc",
     ],
     hdrs = [
         "src/cpp/client/secure_credentials.h",
+    ],
+    language = "c++",
+    deps = [
+        "grpc++_base",
+    ],
+)
+
+grpc_cc_library(
+    name = "grpc++_xds_server",
+    srcs = [
+        "src/cpp/server/xds_server_credentials.cc",
+    ],
+    hdrs = [
         "src/cpp/server/secure_server_credentials.h",
     ],
     language = "c++",
+    public_hdrs = [
+        "include/grpcpp/xds_server_builder.h",
+    ],
     deps = [
         "grpc++_base",
     ],
@@ -574,7 +591,6 @@ grpc_cc_library(
         "src/core/lib/gprpp/global_config_generic.h",
         "src/core/lib/gprpp/host_port.h",
         "src/core/lib/gprpp/manual_constructor.h",
-        "src/core/lib/gprpp/map.h",
         "src/core/lib/gprpp/memory.h",
         "src/core/lib/gprpp/mpscq.h",
         "src/core/lib/gprpp/stat.h",
@@ -1079,6 +1095,7 @@ 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/config_selector.cc",
+        "src/core/ext/filters/client_channel/dynamic_filters.cc",
         "src/core/ext/filters/client_channel/global_subchannel_pool.cc",
         "src/core/ext/filters/client_channel/health/health_check_client.cc",
         "src/core/ext/filters/client_channel/http_connect_handshaker.cc",
@@ -1107,6 +1124,7 @@ grpc_cc_library(
         "src/core/ext/filters/client_channel/client_channel_factory.h",
         "src/core/ext/filters/client_channel/config_selector.h",
         "src/core/ext/filters/client_channel/connector.h",
+        "src/core/ext/filters/client_channel/dynamic_filters.h",
         "src/core/ext/filters/client_channel/global_subchannel_pool.h",
         "src/core/ext/filters/client_channel/health/health_check_client.h",
         "src/core/ext/filters/client_channel/http_connect_handshaker.h",
@@ -1384,6 +1402,17 @@ grpc_cc_library(
     ],
 )
 
+grpc_cc_library(
+    name = "grpc_xds_server_config_fetcher",
+    srcs = [
+        "src/core/ext/xds/xds_server_config_fetcher.cc",
+    ],
+    language = "c++",
+    deps = [
+        "grpc_xds_client",
+    ],
+)
+
 grpc_cc_library(
     name = "grpc_google_mesh_ca_certificate_provider_factory",
     srcs = [
@@ -1412,6 +1441,14 @@ grpc_cc_library(
     ],
 )
 
+grpc_cc_library(
+    name = "grpc_lb_xds_channel_args",
+    hdrs = [
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h",
+    ],
+    language = "c++",
+)
+
 grpc_cc_library(
     name = "grpc_lb_xds_common",
     hdrs = [
@@ -1426,9 +1463,9 @@ grpc_cc_library(
 )
 
 grpc_cc_library(
-    name = "grpc_lb_policy_eds",
+    name = "grpc_lb_policy_xds_cluster_resolver",
     srcs = [
-        "src/core/ext/filters/client_channel/lb_policy/xds/eds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc",
     ],
     external_deps = [
         "absl/strings",
@@ -1455,6 +1492,7 @@ grpc_cc_library(
     deps = [
         "grpc_base",
         "grpc_client_channel",
+        "grpc_lb_xds_channel_args",
         "grpc_lb_xds_common",
         "grpc_xds_client",
     ],
@@ -1709,12 +1747,10 @@ grpc_cc_library(
     name = "grpc_resolver_dns_ares",
     srcs = [
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc",
-        "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc",
-        "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc",
@@ -1880,6 +1916,7 @@ grpc_cc_library(
     deps = [
         "alts_util",
         "grpc_base",
+        "grpc_lb_xds_channel_args",
         "grpc_transport_chttp2_alpn",
         "tsi",
     ],

BUILD.gn

@@ -159,7 +159,6 @@ config("grpc_config") {
         "src/core/lib/gprpp/host_port.cc",
         "src/core/lib/gprpp/host_port.h",
         "src/core/lib/gprpp/manual_constructor.h",
-        "src/core/lib/gprpp/map.h",
         "src/core/lib/gprpp/memory.h",
         "src/core/lib/gprpp/mpscq.cc",
         "src/core/lib/gprpp/mpscq.h",
@@ -224,6 +223,8 @@ config("grpc_config") {
         "src/core/ext/filters/client_channel/config_selector.cc",
         "src/core/ext/filters/client_channel/config_selector.h",
         "src/core/ext/filters/client_channel/connector.h",
+        "src/core/ext/filters/client_channel/dynamic_filters.cc",
+        "src/core/ext/filters/client_channel/dynamic_filters.h",
         "src/core/ext/filters/client_channel/global_subchannel_pool.cc",
         "src/core/ext/filters/client_channel/global_subchannel_pool.h",
         "src/core/ext/filters/client_channel/health/health_check_client.cc",
@@ -256,10 +257,11 @@ config("grpc_config") {
         "src/core/ext/filters/client_channel/lb_policy/subchannel_list.h",
         "src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc",
         "src/core/ext/filters/client_channel/lb_policy/xds/cds.cc",
-        "src/core/ext/filters/client_channel/lb_policy/xds/eds.cc",
         "src/core/ext/filters/client_channel/lb_policy/xds/xds.h",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h",
         "src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc",
         "src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc",
         "src/core/ext/filters/client_channel/lb_policy_factory.h",
         "src/core/ext/filters/client_channel/lb_policy_registry.cc",
         "src/core/ext/filters/client_channel/lb_policy_registry.h",
@@ -271,14 +273,12 @@ config("grpc_config") {
         "src/core/ext/filters/client_channel/resolver.cc",
         "src/core/ext/filters/client_channel/resolver.h",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc",
-        "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc",
         "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_ev_driver_libuv.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h",
-        "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc",
@@ -739,6 +739,7 @@ config("grpc_config") {
         "src/core/ext/xds/xds_client.h",
         "src/core/ext/xds/xds_client_stats.cc",
         "src/core/ext/xds/xds_client_stats.h",
+        "src/core/ext/xds/xds_server_config_fetcher.cc",
         "src/core/lib/avl/avl.cc",
         "src/core/lib/avl/avl.h",
         "src/core/lib/backoff/backoff.cc",
@@ -1427,6 +1428,7 @@ config("grpc_config") {
         "include/grpcpp/support/sync_stream.h",
         "include/grpcpp/support/time.h",
         "include/grpcpp/support/validate_service_config.h",
+        "include/grpcpp/xds_server_builder.h",
         "src/cpp/client/channel_cc.cc",
         "src/cpp/client/client_callback.cc",
         "src/cpp/client/client_context.cc",

CMakeLists.txt

@@ -25,12 +25,12 @@
 cmake_minimum_required(VERSION 3.5.1)
 
 set(PACKAGE_NAME          "grpc")
-set(PACKAGE_VERSION       "1.35.0-dev")
-set(gRPC_CORE_VERSION     "14.0.0")
-set(gRPC_CORE_SOVERSION   "14")
-set(gRPC_CPP_VERSION      "1.35.0-dev")
+set(PACKAGE_VERSION       "1.36.0-dev")
+set(gRPC_CORE_VERSION     "15.0.0")
+set(gRPC_CORE_SOVERSION   "15")
+set(gRPC_CPP_VERSION      "1.36.0-dev")
 set(gRPC_CPP_SOVERSION    "1")
-set(gRPC_CSHARP_VERSION   "2.35.0-dev")
+set(gRPC_CSHARP_VERSION   "2.36.0-dev")
 set(gRPC_CSHARP_SOVERSION "2")
 set(PACKAGE_STRING        "${PACKAGE_NAME} ${PACKAGE_VERSION}")
 set(PACKAGE_TARNAME       "${PACKAGE_NAME}-${PACKAGE_VERSION}")
@@ -698,7 +698,6 @@ if(gRPC_BUILD_TESTS)
   if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
     add_dependencies(buildtests_c udp_server_test)
   endif()
-  add_dependencies(buildtests_c uri_parser_test)
   add_dependencies(buildtests_c useful_test)
   add_dependencies(buildtests_c varint_test)
 
@@ -937,6 +936,7 @@ if(gRPC_BUILD_TESTS)
   add_dependencies(buildtests_cxx tls_security_connector_test)
   add_dependencies(buildtests_cxx too_many_pings_test)
   add_dependencies(buildtests_cxx unknown_frame_bad_client_test)
+  add_dependencies(buildtests_cxx uri_parser_test)
   add_dependencies(buildtests_cxx window_overflow_bad_client_test)
   if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
     add_dependencies(buildtests_cxx work_serializer_test)
@@ -1453,6 +1453,7 @@ 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/config_selector.cc
+  src/core/ext/filters/client_channel/dynamic_filters.cc
   src/core/ext/filters/client_channel/global_subchannel_pool.cc
   src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
@@ -1471,20 +1472,18 @@ add_library(grpc
   src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
   src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc
   src/core/ext/filters/client_channel/lb_policy/xds/cds.cc
-  src/core/ext/filters/client_channel/lb_policy/xds/eds.cc
   src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc
   src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc
   src/core/ext/filters/client_channel/lb_policy_registry.cc
   src/core/ext/filters/client_channel/local_subchannel_pool.cc
   src/core/ext/filters/client_channel/proxy_mapper_registry.cc
   src/core/ext/filters/client_channel/resolver.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
-  src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
-  src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc
@@ -1721,6 +1720,7 @@ add_library(grpc
   src/core/ext/xds/xds_certificate_provider.cc
   src/core/ext/xds/xds_client.cc
   src/core/ext/xds/xds_client_stats.cc
+  src/core/ext/xds/xds_server_config_fetcher.cc
   src/core/lib/avl/avl.cc
   src/core/lib/backoff/backoff.cc
   src/core/lib/channel/channel_args.cc
@@ -2254,6 +2254,7 @@ 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/config_selector.cc
+  src/core/ext/filters/client_channel/dynamic_filters.cc
   src/core/ext/filters/client_channel/global_subchannel_pool.cc
   src/core/ext/filters/client_channel/health/health_check_client.cc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
@@ -2276,12 +2277,10 @@ add_library(grpc_unsecure
   src/core/ext/filters/client_channel/proxy_mapper_registry.cc
   src/core/ext/filters/client_channel/resolver.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
-  src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
-  src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc
@@ -2953,6 +2952,7 @@ foreach(_hdr
   include/grpcpp/support/sync_stream.h
   include/grpcpp/support/time.h
   include/grpcpp/support/validate_service_config.h
+  include/grpcpp/xds_server_builder.h
 )
   string(REPLACE "include/" "" _path ${_hdr})
   get_filename_component(_path ${_path} PATH)
@@ -3781,15 +3781,17 @@ endif()
 endif()
 
 add_library(upb
+  third_party/upb/upb/decode_fast.c
   third_party/upb/upb/decode.c
+  third_party/upb/upb/def.c
   third_party/upb/upb/encode.c
+  third_party/upb/upb/json_decode.c
+  third_party/upb/upb/json_encode.c
   third_party/upb/upb/msg.c
-  third_party/upb/upb/port.c
-  third_party/upb/upb/table.c
-  third_party/upb/upb/upb.c
-  third_party/upb/upb/def.c
   third_party/upb/upb/reflection.c
+  third_party/upb/upb/table.c
   third_party/upb/upb/text_encode.c
+  third_party/upb/upb/upb.c
   src/core/ext/upb-generated/google/protobuf/any.upb.c
   src/core/ext/upb-generated/google/protobuf/descriptor.upb.c
   src/core/ext/upb-generated/google/protobuf/duration.upb.c
@@ -8020,36 +8022,6 @@ endif()
 endif()
 if(gRPC_BUILD_TESTS)
 
-add_executable(uri_parser_test
-  test/core/uri/uri_parser_test.cc
-)
-
-target_include_directories(uri_parser_test
-  PRIVATE
-    ${CMAKE_CURRENT_SOURCE_DIR}
-    ${CMAKE_CURRENT_SOURCE_DIR}/include
-    ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
-    ${_gRPC_RE2_INCLUDE_DIR}
-    ${_gRPC_SSL_INCLUDE_DIR}
-    ${_gRPC_UPB_GENERATED_DIR}
-    ${_gRPC_UPB_GRPC_GENERATED_DIR}
-    ${_gRPC_UPB_INCLUDE_DIR}
-    ${_gRPC_ZLIB_INCLUDE_DIR}
-)
-
-target_link_libraries(uri_parser_test
-  ${_gRPC_ALLTARGETS_LIBRARIES}
-  grpc_test_util
-  grpc
-  gpr
-  address_sorting
-  upb
-)
-
-
-endif()
-if(gRPC_BUILD_TESTS)
-
 add_executable(useful_test
   test/core/gpr/useful_test.cc
 )
@@ -15144,6 +15116,44 @@ target_link_libraries(unknown_frame_bad_client_test
 )
 
 
+endif()
+if(gRPC_BUILD_TESTS)
+
+add_executable(uri_parser_test
+  test/core/uri/uri_parser_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+target_include_directories(uri_parser_test
+  PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
+    ${_gRPC_RE2_INCLUDE_DIR}
+    ${_gRPC_SSL_INCLUDE_DIR}
+    ${_gRPC_UPB_GENERATED_DIR}
+    ${_gRPC_UPB_GRPC_GENERATED_DIR}
+    ${_gRPC_UPB_INCLUDE_DIR}
+    ${_gRPC_ZLIB_INCLUDE_DIR}
+    third_party/googletest/googletest/include
+    third_party/googletest/googletest
+    third_party/googletest/googlemock/include
+    third_party/googletest/googlemock
+    ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(uri_parser_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+  grpc_test_util
+  grpc
+  gpr
+  address_sorting
+  upb
+)
+
+
 endif()
 if(gRPC_BUILD_TESTS)
 

Makefile

@@ -454,9 +454,9 @@ E = @echo
 Q = @
 endif
 
-CORE_VERSION = 14.0.0
-CPP_VERSION = 1.35.0-dev
-CSHARP_VERSION = 2.35.0-dev
+CORE_VERSION = 15.0.0
+CPP_VERSION = 1.36.0-dev
+CSHARP_VERSION = 2.36.0-dev
 
 CPPFLAGS_NO_ARCH += $(addprefix -I, $(INCLUDES)) $(addprefix -D, $(DEFINES))
 CPPFLAGS += $(CPPFLAGS_NO_ARCH) $(ARCH_FLAGS)
@@ -492,7 +492,7 @@ SHARED_EXT_CORE = dll
 SHARED_EXT_CPP = dll
 SHARED_EXT_CSHARP = dll
 SHARED_PREFIX =
-SHARED_VERSION_CORE = -14
+SHARED_VERSION_CORE = -15
 SHARED_VERSION_CPP = -1
 SHARED_VERSION_CSHARP = -2
 else ifeq ($(SYSTEM),Darwin)
@@ -891,8 +891,8 @@ $(LIBDIR)/$(CONFIG)/libaddress_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE):
 ifeq ($(SYSTEM),Darwin)
 	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)address_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libaddress_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBADDRESS_SORTING_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libaddress_sorting.so.14 -o $(LIBDIR)/$(CONFIG)/libaddress_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBADDRESS_SORTING_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
-	$(Q) ln -sf $(SHARED_PREFIX)address_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libaddress_sorting$(SHARED_VERSION_CORE).so.14
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libaddress_sorting.so.15 -o $(LIBDIR)/$(CONFIG)/libaddress_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBADDRESS_SORTING_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
+	$(Q) ln -sf $(SHARED_PREFIX)address_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libaddress_sorting$(SHARED_VERSION_CORE).so.15
 	$(Q) ln -sf $(SHARED_PREFIX)address_sorting$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libaddress_sorting$(SHARED_VERSION_CORE).so
 endif
 endif
@@ -1019,8 +1019,8 @@ $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGPR_OB
 ifeq ($(SYSTEM),Darwin)
 	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgpr.so.14 -o $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
-	$(Q) ln -sf $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).so.14
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgpr.so.15 -o $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
+	$(Q) ln -sf $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).so.15
 	$(Q) ln -sf $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).so
 endif
 endif
@@ -1042,6 +1042,7 @@ 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/config_selector.cc \
+    src/core/ext/filters/client_channel/dynamic_filters.cc \
     src/core/ext/filters/client_channel/global_subchannel_pool.cc \
     src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
@@ -1060,20 +1061,18 @@ LIBGRPC_SRC = \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
     src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/cds.cc \
-    src/core/ext/filters/client_channel/lb_policy/xds/eds.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc \
     src/core/ext/filters/client_channel/lb_policy_registry.cc \
     src/core/ext/filters/client_channel/local_subchannel_pool.cc \
     src/core/ext/filters/client_channel/proxy_mapper_registry.cc \
     src/core/ext/filters/client_channel/resolver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
-    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc \
-    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc \
@@ -1310,6 +1309,7 @@ LIBGRPC_SRC = \
     src/core/ext/xds/xds_certificate_provider.cc \
     src/core/ext/xds/xds_client.cc \
     src/core/ext/xds/xds_client_stats.cc \
+    src/core/ext/xds/xds_server_config_fetcher.cc \
     src/core/lib/avl/avl.cc \
     src/core/lib/backoff/backoff.cc \
     src/core/lib/channel/channel_args.cc \
@@ -1611,8 +1611,8 @@ $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGRPC_
 ifeq ($(SYSTEM),Darwin)
 	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc.so.14 -o $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
-	$(Q) ln -sf $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).so.14
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc.so.15 -o $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
+	$(Q) ln -sf $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).so.15
 	$(Q) ln -sf $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).so
 endif
 endif
@@ -1669,8 +1669,8 @@ $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE):
 ifeq ($(SYSTEM),Darwin)
 	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CSHARP_EXT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_csharp_ext.so.14 -o $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CSHARP_EXT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
-	$(Q) ln -sf $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CORE).so.14
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_csharp_ext.so.15 -o $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CSHARP_EXT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
+	$(Q) ln -sf $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CORE).so.15
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CORE).so
 endif
 endif
@@ -1696,6 +1696,7 @@ 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/config_selector.cc \
+    src/core/ext/filters/client_channel/dynamic_filters.cc \
     src/core/ext/filters/client_channel/global_subchannel_pool.cc \
     src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
@@ -1718,12 +1719,10 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/proxy_mapper_registry.cc \
     src/core/ext/filters/client_channel/resolver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
-    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc \
-    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc \
@@ -2008,8 +2007,8 @@ $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $
 ifeq ($(SYSTEM),Darwin)
 	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_unsecure.so.14 -o $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
-	$(Q) ln -sf $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).so.14
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_unsecure.so.15 -o $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
+	$(Q) ln -sf $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).so.15
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).so
 endif
 endif
@@ -2367,15 +2366,17 @@ endif
 
 # start of build recipe for library "upb" (generated by makelib(lib) template function)
 LIBUPB_SRC = \
+    third_party/upb/upb/decode_fast.c \
     third_party/upb/upb/decode.c \
+    third_party/upb/upb/def.c \
     third_party/upb/upb/encode.c \
+    third_party/upb/upb/json_decode.c \
+    third_party/upb/upb/json_encode.c \
     third_party/upb/upb/msg.c \
-    third_party/upb/upb/port.c \
-    third_party/upb/upb/table.c \
-    third_party/upb/upb/upb.c \
-    third_party/upb/upb/def.c \
     third_party/upb/upb/reflection.c \
+    third_party/upb/upb/table.c \
     third_party/upb/upb/text_encode.c \
+    third_party/upb/upb/upb.c \
     src/core/ext/upb-generated/google/protobuf/any.upb.c \
     src/core/ext/upb-generated/google/protobuf/descriptor.upb.c \
     src/core/ext/upb-generated/google/protobuf/duration.upb.c \
@@ -2419,8 +2420,8 @@ $(LIBDIR)/$(CONFIG)/libupb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBUPB_OB
 ifeq ($(SYSTEM),Darwin)
 	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)upb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libupb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBUPB_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libupb.so.14 -o $(LIBDIR)/$(CONFIG)/libupb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBUPB_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
-	$(Q) ln -sf $(SHARED_PREFIX)upb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libupb$(SHARED_VERSION_CORE).so.14
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libupb.so.15 -o $(LIBDIR)/$(CONFIG)/libupb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBUPB_OBJS) $(ZLIB_MERGE_LIBS) $(CARES_MERGE_LIBS) $(ADDRESS_SORTING_MERGE_LIBS) $(RE2_MERGE_LIBS) $(UPB_MERGE_LIBS) $(GRPC_ABSEIL_MERGE_LIBS) $(LDLIBS)
+	$(Q) ln -sf $(SHARED_PREFIX)upb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libupb$(SHARED_VERSION_CORE).so.15
 	$(Q) ln -sf $(SHARED_PREFIX)upb$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libupb$(SHARED_VERSION_CORE).so
 endif
 endif
@@ -2666,9 +2667,9 @@ ifneq ($(OPENSSL_DEP),)
 # 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/cds.cc: $(OPENSSL_DEP)
-src/core/ext/filters/client_channel/lb_policy/xds/eds.cc: $(OPENSSL_DEP)
 src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc: $(OPENSSL_DEP)
 src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc: $(OPENSSL_DEP)
+src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc: $(OPENSSL_DEP)
 src/core/ext/filters/client_channel/resolver/xds/xds_resolver.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)
@@ -2822,6 +2823,7 @@ src/core/ext/xds/xds_bootstrap.cc: $(OPENSSL_DEP)
 src/core/ext/xds/xds_certificate_provider.cc: $(OPENSSL_DEP)
 src/core/ext/xds/xds_client.cc: $(OPENSSL_DEP)
 src/core/ext/xds/xds_client_stats.cc: $(OPENSSL_DEP)
+src/core/ext/xds/xds_server_config_fetcher.cc: $(OPENSSL_DEP)
 src/core/lib/http/httpcli_security_connector.cc: $(OPENSSL_DEP)
 src/core/lib/security/authorization/authorization_engine.cc: $(OPENSSL_DEP)
 src/core/lib/security/authorization/evaluate_args.cc: $(OPENSSL_DEP)

Rakefile

@@ -121,7 +121,7 @@ task 'gem:native' do
   verbose = ENV['V'] || '0'
 
   grpc_config = ENV['GRPC_CONFIG'] || 'opt'
-  ruby_cc_versions = '2.7.0:2.6.0:2.5.0:2.4.0:2.3.0'
+  ruby_cc_versions = ['3.0.0', '2.7.0', '2.6.0', '2.5.0', '2.4.0', '2.3.0'].join(':')
 
   if RUBY_PLATFORM =~ /darwin/
     FileUtils.touch 'grpc_c.32.ruby'
@@ -139,20 +139,22 @@ task 'gem:native' do
         gem update --system --no-document && \
         bundle && \
         rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem pkg/#{spec.full_name}.gem \
-          RUBY_CC_VERSION=#{ruby_cc_versions} V=#{verbose} GRPC_CONFIG=#{grpc_config}
+          RUBY_CC_VERSION=#{ruby_cc_versions} \
+          V=#{verbose} \
+          GRPC_CONFIG=#{grpc_config}
       EOT
     end
     # Truncate grpc_c.*.ruby files because they're for Windows only.
     File.truncate('grpc_c.32.ruby', 0)
     File.truncate('grpc_c.64.ruby', 0)
     ['x86_64-linux', 'x86-linux'].each do |plat|
-      run_rake_compiler plat,  <<-EOT
+      run_rake_compiler plat, <<-EOT
         gem update --system --no-document && \
         bundle && \
         rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem pkg/#{spec.full_name}.gem \
-          RUBY_CC_VERSION=#{ruby_cc_versions} V=#{verbose} GRPC_CONFIG=#{grpc_config} &&
-        sudo chmod -R a+rw pkg &&
-        patchelf_gem.sh pkg/#{spec.full_name}-#{plat}.gem
+          RUBY_CC_VERSION=#{ruby_cc_versions} \
+          V=#{verbose} \
+          GRPC_CONFIG=#{grpc_config}
       EOT
     end
   end

bazel/grpc_deps.bzl

@@ -21,6 +21,11 @@ def grpc_deps():
         actual = "@upb//:textformat",
     )
 
+    native.bind(
+        name = "upb_json_lib",
+        actual = "@upb//:json",
+    )
+
     native.bind(
         name = "absl",
         actual = "@com_google_absl//absl",
@@ -288,11 +293,11 @@ def grpc_deps():
     if "upb" not in native.existing_rules():
         http_archive(
             name = "upb",
-            sha256 = "7992217989f3156f8109931c1fc6db3434b7414957cb82371552377beaeb9d6c",
-            strip_prefix = "upb-382d5afc60e05470c23e8de19b19fc5ad231e732",
+            sha256 = "c0b97bf91dfea7e8d7579c24e2ecdd02d10b00f3c5defc3dce23d95100d0e664",
+            strip_prefix = "upb-60607da72e89ba0c84c84054d2e562d8b6b61177",
             urls = [
-                "https://storage.googleapis.com/grpc-bazel-mirror/github.com/protocolbuffers/upb/archive/382d5afc60e05470c23e8de19b19fc5ad231e732.tar.gz",
-                "https://github.com/protocolbuffers/upb/archive/382d5afc60e05470c23e8de19b19fc5ad231e732.tar.gz",
+                "https://storage.googleapis.com/grpc-bazel-mirror/github.com/protocolbuffers/upb/archive/60607da72e89ba0c84c84054d2e562d8b6b61177.tar.gz",
+                "https://github.com/protocolbuffers/upb/archive/60607da72e89ba0c84c84054d2e562d8b6b61177.tar.gz",
             ],
         )
 

bazel/grpc_extra_deps.bzl

@@ -7,7 +7,7 @@ load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_depe
 load("@build_bazel_rules_apple//apple:repositories.bzl", "apple_rules_dependencies")
 load("@build_bazel_apple_support//lib:repositories.bzl", "apple_support_dependencies")
 
-def grpc_extra_deps():
+def grpc_extra_deps(ignore_version_differences = False):
     """Loads the extra dependencies.
 
     These are necessary for using the external repositories defined in
@@ -35,6 +35,6 @@ def grpc_extra_deps():
     go_rules_dependencies()
     go_register_toolchains()
 
-    apple_rules_dependencies()
+    apple_rules_dependencies(ignore_version_differences = ignore_version_differences)
 
     apple_support_dependencies()

bazel/update_mirror.sh

@@ -60,6 +60,10 @@ upload github.com/bazelbuild/bazel/releases/download/2.2.0/bazel-2.2.0-linux-x86
 upload github.com/bazelbuild/bazel/releases/download/2.2.0/bazel-2.2.0-darwin-x86_64
 upload github.com/bazelbuild/bazel/releases/download/2.2.0/bazel-2.2.0-windows-x86_64.exe
 
+upload github.com/bazelbuild/bazel/releases/download/3.7.1/bazel-3.7.1-linux-x86_64
+upload github.com/bazelbuild/bazel/releases/download/3.7.1/bazel-3.7.1-darwin-x86_64
+upload github.com/bazelbuild/bazel/releases/download/3.7.1/bazel-3.7.1-windows-x86_64.exe
+
 # Collect the github archives to mirror from grpc_deps.bzl
 grep -o '"https://github.com/[^"]*"' bazel/grpc_deps.bzl | sed 's/^"https:\/\///' | sed 's/"$//' | while read -r line ; do
     echo "Updating mirror for ${line}"

build_autogenerated.yaml

@@ -303,7 +303,6 @@ libs:
   - src/core/lib/gprpp/global_config_generic.h
   - src/core/lib/gprpp/host_port.h
   - src/core/lib/gprpp/manual_constructor.h
-  - src/core/lib/gprpp/map.h
   - src/core/lib/gprpp/memory.h
   - src/core/lib/gprpp/mpscq.h
   - src/core/lib/gprpp/stat.h
@@ -391,6 +390,7 @@ libs:
   - src/core/ext/filters/client_channel/client_channel_factory.h
   - src/core/ext/filters/client_channel/config_selector.h
   - src/core/ext/filters/client_channel/connector.h
+  - src/core/ext/filters/client_channel/dynamic_filters.h
   - src/core/ext/filters/client_channel/global_subchannel_pool.h
   - src/core/ext/filters/client_channel/health/health_check_client.h
   - src/core/ext/filters/client_channel/http_connect_handshaker.h
@@ -406,6 +406,7 @@ libs:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h
   - src/core/ext/filters/client_channel/lb_policy/subchannel_list.h
   - src/core/ext/filters/client_channel/lb_policy/xds/xds.h
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h
   - src/core/ext/filters/client_channel/lb_policy_factory.h
   - src/core/ext/filters/client_channel/lb_policy_registry.h
   - src/core/ext/filters/client_channel/local_subchannel_pool.h
@@ -873,6 +874,7 @@ libs:
   - 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/config_selector.cc
+  - src/core/ext/filters/client_channel/dynamic_filters.cc
   - src/core/ext/filters/client_channel/global_subchannel_pool.cc
   - src/core/ext/filters/client_channel/health/health_check_client.cc
   - src/core/ext/filters/client_channel/http_connect_handshaker.cc
@@ -891,20 +893,18 @@ libs:
   - src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
   - src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc
   - src/core/ext/filters/client_channel/lb_policy/xds/cds.cc
-  - src/core/ext/filters/client_channel/lb_policy/xds/eds.cc
   - src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc
   - src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc
   - src/core/ext/filters/client_channel/lb_policy_registry.cc
   - src/core/ext/filters/client_channel/local_subchannel_pool.cc
   - src/core/ext/filters/client_channel/proxy_mapper_registry.cc
   - src/core/ext/filters/client_channel/resolver.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
-  - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
-  - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc
@@ -1141,6 +1141,7 @@ libs:
   - src/core/ext/xds/xds_certificate_provider.cc
   - src/core/ext/xds/xds_client.cc
   - src/core/ext/xds/xds_client_stats.cc
+  - src/core/ext/xds/xds_server_config_fetcher.cc
   - src/core/lib/avl/avl.cc
   - src/core/lib/backoff/backoff.cc
   - src/core/lib/channel/channel_args.cc
@@ -1560,6 +1561,7 @@ libs:
   - src/core/ext/filters/client_channel/client_channel_factory.h
   - src/core/ext/filters/client_channel/config_selector.h
   - src/core/ext/filters/client_channel/connector.h
+  - src/core/ext/filters/client_channel/dynamic_filters.h
   - src/core/ext/filters/client_channel/global_subchannel_pool.h
   - src/core/ext/filters/client_channel/health/health_check_client.h
   - src/core/ext/filters/client_channel/http_connect_handshaker.h
@@ -1803,6 +1805,7 @@ libs:
   - 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/config_selector.cc
+  - src/core/ext/filters/client_channel/dynamic_filters.cc
   - src/core/ext/filters/client_channel/global_subchannel_pool.cc
   - src/core/ext/filters/client_channel/health/health_check_client.cc
   - src/core/ext/filters/client_channel/http_connect_handshaker.cc
@@ -1825,12 +1828,10 @@ libs:
   - src/core/ext/filters/client_channel/proxy_mapper_registry.cc
   - src/core/ext/filters/client_channel/resolver.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
-  - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
-  - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc
@@ -2298,6 +2299,7 @@ libs:
   - include/grpcpp/support/sync_stream.h
   - include/grpcpp/support/time.h
   - include/grpcpp/support/validate_service_config.h
+  - include/grpcpp/xds_server_builder.h
   headers:
   - src/cpp/client/create_channel_internal.h
   - src/cpp/client/secure_credentials.h
@@ -3259,7 +3261,6 @@ targets:
   uses_polling: false
 - name: concurrent_connectivity_test
   build: test
-  run: false
   language: c
   headers: []
   src:
@@ -4625,18 +4626,6 @@ targets:
   - linux
   - posix
   - mac
-- name: uri_parser_test
-  build: test
-  language: c
-  headers: []
-  src:
-  - test/core/uri/uri_parser_test.cc
-  deps:
-  - grpc_test_util
-  - grpc
-  - gpr
-  - address_sorting
-  - upb
 - name: useful_test
   build: test
   language: c
@@ -5421,7 +5410,6 @@ targets:
 - name: cancel_ares_query_test
   gtest: true
   build: test
-  run: false
   language: c++
   headers:
   - test/core/end2end/cq_verifier.h
@@ -7523,7 +7511,6 @@ targets:
 - name: stranded_event_test
   gtest: true
   build: test
-  run: false
   language: c++
   headers:
   - test/core/end2end/cq_verifier.h
@@ -7776,6 +7763,19 @@ targets:
   corpus_dirs:
   - test/core/uri/uri_corpus
   maxlen: 128
+- name: uri_parser_test
+  gtest: true
+  build: test
+  language: c++
+  headers: []
+  src:
+  - test/core/uri/uri_parser_test.cc
+  deps:
+  - grpc_test_util
+  - grpc
+  - gpr
+  - address_sorting
+  - upb
 - name: window_overflow_bad_client_test
   gtest: true
   build: test

build_config.rb

@@ -13,5 +13,5 @@
 # limitations under the License.
 
 module GrpcBuildConfig
-  CORE_WINDOWS_DLL = '/tmp/libs/opt/grpc-14.dll'
+  CORE_WINDOWS_DLL = '/tmp/libs/opt/grpc-15.dll'
 end

build_handwritten.yaml

@@ -12,11 +12,11 @@ settings:
   '#08': Use "-preN" suffixes to identify pre-release versions
   '#09': Per-language overrides are possible with (eg) ruby_version tag here
   '#10': See the expand_version.py for all the quirks here
-  core_version: 14.0.0
+  core_version: 15.0.0
   csharp_major_version: 2
-  g_stands_for: gecko
+  g_stands_for: gummybear
   protobuf_version: 3.13.0
-  version: 1.35.0-dev
+  version: 1.36.0-dev
 targets:
 - name: check_epollexclusive
   build: tool

config.m4

@@ -48,6 +48,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/client_channel_factory.cc \
     src/core/ext/filters/client_channel/client_channel_plugin.cc \
     src/core/ext/filters/client_channel/config_selector.cc \
+    src/core/ext/filters/client_channel/dynamic_filters.cc \
     src/core/ext/filters/client_channel/global_subchannel_pool.cc \
     src/core/ext/filters/client_channel/health/health_check_client.cc \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
@@ -66,20 +67,18 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
     src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/cds.cc \
-    src/core/ext/filters/client_channel/lb_policy/xds/eds.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc \
     src/core/ext/filters/client_channel/lb_policy_registry.cc \
     src/core/ext/filters/client_channel/local_subchannel_pool.cc \
     src/core/ext/filters/client_channel/proxy_mapper_registry.cc \
     src/core/ext/filters/client_channel/resolver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
-    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc \
-    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc \
@@ -317,6 +316,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/xds/xds_certificate_provider.cc \
     src/core/ext/xds/xds_client.cc \
     src/core/ext/xds/xds_client_stats.cc \
+    src/core/ext/xds/xds_server_config_fetcher.cc \
     src/core/lib/avl/avl.cc \
     src/core/lib/backoff/backoff.cc \
     src/core/lib/channel/channel_args.cc \
@@ -987,10 +987,12 @@ if test "$PHP_GRPC" != "no"; then
     third_party/re2/util/rune.cc \
     third_party/re2/util/strutil.cc \
     third_party/upb/upb/decode.c \
+    third_party/upb/upb/decode_fast.c \
     third_party/upb/upb/def.c \
     third_party/upb/upb/encode.c \
+    third_party/upb/upb/json_decode.c \
+    third_party/upb/upb/json_encode.c \
     third_party/upb/upb/msg.c \
-    third_party/upb/upb/port.c \
     third_party/upb/upb/reflection.c \
     third_party/upb/upb/table.c \
     third_party/upb/upb/text_encode.c \

config.w32

@@ -15,6 +15,7 @@ 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\\config_selector.cc " +
+    "src\\core\\ext\\filters\\client_channel\\dynamic_filters.cc " +
     "src\\core\\ext\\filters\\client_channel\\global_subchannel_pool.cc " +
     "src\\core\\ext\\filters\\client_channel\\health\\health_check_client.cc " +
     "src\\core\\ext\\filters\\client_channel\\http_connect_handshaker.cc " +
@@ -33,20 +34,18 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\round_robin\\round_robin.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\weighted_target\\weighted_target.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\cds.cc " +
-    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\eds.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds_cluster_impl.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds_cluster_manager.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds_cluster_resolver.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy_registry.cc " +
     "src\\core\\ext\\filters\\client_channel\\local_subchannel_pool.cc " +
     "src\\core\\ext\\filters\\client_channel\\proxy_mapper_registry.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\dns_resolver_ares.cc " +
-    "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_ev_driver.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_ev_driver_libuv.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_ev_driver_posix.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_ev_driver_windows.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_wrapper.cc " +
-    "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_wrapper_fallback.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_wrapper_libuv.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_wrapper_posix.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_wrapper_windows.cc " +
@@ -284,6 +283,7 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\xds\\xds_certificate_provider.cc " +
     "src\\core\\ext\\xds\\xds_client.cc " +
     "src\\core\\ext\\xds\\xds_client_stats.cc " +
+    "src\\core\\ext\\xds\\xds_server_config_fetcher.cc " +
     "src\\core\\lib\\avl\\avl.cc " +
     "src\\core\\lib\\backoff\\backoff.cc " +
     "src\\core\\lib\\channel\\channel_args.cc " +
@@ -954,10 +954,12 @@ if (PHP_GRPC != "no") {
     "third_party\\re2\\util\\rune.cc " +
     "third_party\\re2\\util\\strutil.cc " +
     "third_party\\upb\\upb\\decode.c " +
+    "third_party\\upb\\upb\\decode_fast.c " +
     "third_party\\upb\\upb\\def.c " +
     "third_party\\upb\\upb\\encode.c " +
+    "third_party\\upb\\upb\\json_decode.c " +
+    "third_party\\upb\\upb\\json_encode.c " +
     "third_party\\upb\\upb\\msg.c " +
-    "third_party\\upb\\upb\\port.c " +
     "third_party\\upb\\upb\\reflection.c " +
     "third_party\\upb\\upb\\table.c " +
     "third_party\\upb\\upb\\text_encode.c " +

doc/environment_variables.md

@@ -57,7 +57,6 @@ some configuration as environment variables that can be set.
   - compression - traces compression operations
   - connectivity_state - traces connectivity state changes to channels
   - cronet - traces state in the cronet transport engine
-  - eds_lb - traces eds LB policy
   - executor - traces grpc's internal thread pool ('the executor')
   - glb - traces the grpclb load balancer
   - handshaker - traces handshaking state
@@ -91,6 +90,7 @@ some configuration as environment variables that can be set.
   - xds_client - traces xds client
   - xds_cluster_manager_lb - traces cluster manager LB policy
   - xds_cluster_impl_lb - traces cluster impl LB policy
+  - xds_cluster_resolver_lb - traces xds cluster resolver LB policy
   - xds_resolver - traces xds resolver
 
   The following tracers will only run in binaries built in DEBUG mode. This is

doc/g_stands_for.md

@@ -34,4 +34,5 @@
 - 1.32 'g' stands for ['giggle'](https://github.com/grpc/grpc/tree/v1.32.x)
 - 1.33 'g' stands for ['geeky'](https://github.com/grpc/grpc/tree/v1.33.x)
 - 1.34 'g' stands for ['gauntlet'](https://github.com/grpc/grpc/tree/v1.34.x)
-- 1.35 'g' stands for ['gecko'](https://github.com/grpc/grpc/tree/master)
+- 1.35 'g' stands for ['gecko'](https://github.com/grpc/grpc/tree/v1.35.x)
+- 1.36 'g' stands for ['gummybear'](https://github.com/grpc/grpc/tree/master)

doc/grpc_xds_features.md

@@ -34,8 +34,12 @@ The optional `load_balancing_weight` is always ignored.
 Initially, only `google_default` channel creds will be supported
 to authenticate with the xDS server.
 
-Features | gRFCs  | [C++, Python,<br> Ruby, PHP, C#](https://github.com/grpc/grpc/releases) | [Java](https://github.com/grpc/grpc-java/releases) | [Go](https://github.com/grpc/grpc-go/releases) | [Node](https://github.com/grpc/grpc-node/releases)
+The gRPC language implementations not listed in the table below do not support
+xDS features.
+
+Features | gRFCs  | [C++, Python,<br> Ruby, PHP](https://github.com/grpc/grpc/releases) | [Java](https://github.com/grpc/grpc-java/releases) | [Go](https://github.com/grpc/grpc-go/releases) | [Node](https://github.com/grpc/grpc-node/releases)
 ---------|--------|--------------|------|------|------
 **xDS Infrastructure in gRPC client channel:**<ul><li>LDS->RDS->CDS->EDS flow</li><li>ADS stream</li></ul> | [A27](https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md) | v1.30.0  | v1.30.0 | v1.30.0 | v1.2.0 |
 **Load Balancing:**<ul><li>[Virtual host](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-virtualhost) domains matching</li><li>Only default path ("" or "/") matching</li><li>Priority-based weighted round-robin locality picking</li><li>Round-robin endpoint picking within locality</li><li>[Cluster](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#envoy-api-msg-route-routeaction) route action</li><li>Client-side Load reporting via [LRS](https://github.com/envoyproxy/data-plane-api/blob/master/envoy/service/load_stats/v2/lrs.proto)</li></ul> | [A27](https://github.com/grpc/proposal/blob/master/A27-xds-global-load-balancing.md) | v1.30.0  | v1.30.0 | v1.30.0 | v1.2.0 |
-Request matching based on:<ul><li>[Path](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-routematch) (prefix, full path and safe regex)</li><li>[Headers](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-headermatcher)</li></ul>Request routing to multiple clusters based on [weights](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-weightedcluster) | [A28](https://github.com/grpc/proposal/blob/master/A28-xds-traffic-splitting-and-routing.md) | v1.31.0 | v1.31.0 | v1.31.0 | |
+Request matching based on:<ul><li>[Path](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-routematch) (prefix, full path and safe regex)</li><ul><li>[case_sensitive](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-routematch) must be true else config is NACKed</li></ul><li>[Headers](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-headermatcher)</li></ul>Request routing to multiple clusters based on [weights](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-weightedcluster) | [A28](https://github.com/grpc/proposal/blob/master/A28-xds-traffic-splitting-and-routing.md) | v1.31.0 | v1.31.0 | v1.31.0 | |
+Case insensitive prefix/full path matching:<ul><li>[case_sensitive](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route_components.proto#route-routematch) can be true or false</li></ul> | | v1.34.0 | v1.34.0 | v1.34.0 | |

examples/BUILD

@@ -1,252 +0,0 @@
-# Copyright 2017 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.
-
-licenses(["notice"])  # 3-clause BSD
-
-package(default_visibility = ["//visibility:public"])
-
-load("@grpc_python_dependencies//:requirements.bzl", "requirement")
-load("@rules_proto//proto:defs.bzl", "proto_library")
-load("//bazel:cc_grpc_library.bzl", "cc_grpc_library")
-load("//bazel:grpc_build_system.bzl", "grpc_proto_library")
-load("//bazel:python_rules.bzl", "py_grpc_library", "py_proto_library")
-
-grpc_proto_library(
-    name = "auth_sample",
-    srcs = ["protos/auth_sample.proto"],
-)
-
-grpc_proto_library(
-    name = "hellostreamingworld",
-    srcs = ["protos/hellostreamingworld.proto"],
-)
-
-# The following three rules demonstrate the usage of the cc_grpc_library rule in
-# in a mode compatible with the native proto_library and cc_proto_library rules.
-proto_library(
-    name = "helloworld_proto",
-    srcs = ["protos/helloworld.proto"],
-)
-
-cc_proto_library(
-    name = "helloworld_cc_proto",
-    deps = [":helloworld_proto"],
-)
-
-cc_grpc_library(
-    name = "helloworld_cc_grpc",
-    srcs = [":helloworld_proto"],
-    grpc_only = True,
-    deps = [":helloworld_cc_proto"],
-)
-
-grpc_proto_library(
-    name = "route_guide",
-    srcs = ["protos/route_guide.proto"],
-)
-
-proto_library(
-    name = "keyvaluestore_proto",
-    srcs = ["protos/keyvaluestore.proto"],
-)
-
-grpc_proto_library(
-    name = "keyvaluestore",
-    srcs = ["protos/keyvaluestore.proto"],
-)
-
-proto_library(
-    name = "protos/helloworld_proto",
-    srcs = ["protos/helloworld.proto"],
-)
-
-py_proto_library(
-    name = "helloworld_py_pb2",
-    deps = [":protos/helloworld_proto"],
-)
-
-py_grpc_library(
-    name = "helloworld_py_pb2_grpc",
-    srcs = [":protos/helloworld_proto"],
-    deps = [":helloworld_py_pb2"],
-)
-
-cc_binary(
-    name = "greeter_client",
-    srcs = ["cpp/helloworld/greeter_client.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "greeter_async_client",
-    srcs = ["cpp/helloworld/greeter_async_client.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "greeter_async_client2",
-    srcs = ["cpp/helloworld/greeter_async_client2.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "greeter_server",
-    srcs = ["cpp/helloworld/greeter_server.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-        "//:grpc++_reflection",
-    ],
-)
-
-cc_binary(
-    name = "greeter_async_server",
-    srcs = ["cpp/helloworld/greeter_async_server.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "metadata_client",
-    srcs = ["cpp/metadata/greeter_client.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "metadata_server",
-    srcs = ["cpp/metadata/greeter_server.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "lb_client",
-    srcs = ["cpp/load_balancing/greeter_client.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "lb_server",
-    srcs = ["cpp/load_balancing/greeter_server.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "compression_client",
-    srcs = ["cpp/compression/greeter_client.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "compression_server",
-    srcs = ["cpp/compression/greeter_server.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":helloworld_cc_grpc",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "keyvaluestore_client",
-    srcs = [
-        "cpp/keyvaluestore/caching_interceptor.h",
-        "cpp/keyvaluestore/client.cc",
-    ],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":keyvaluestore",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "keyvaluestore_server",
-    srcs = ["cpp/keyvaluestore/server.cc"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":keyvaluestore",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "route_guide_client",
-    srcs = [
-        "cpp/route_guide/helper.cc",
-        "cpp/route_guide/helper.h",
-        "cpp/route_guide/route_guide_client.cc",
-    ],
-    data = ["cpp/route_guide/route_guide_db.json"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":route_guide",
-        "//:grpc++",
-    ],
-)
-
-cc_binary(
-    name = "route_guide_server",
-    srcs = [
-        "cpp/route_guide/helper.cc",
-        "cpp/route_guide/helper.h",
-        "cpp/route_guide/route_guide_server.cc",
-    ],
-    data = ["cpp/route_guide/route_guide_db.json"],
-    defines = ["BAZEL_BUILD"],
-    deps = [
-        ":route_guide",
-        "//:grpc++",
-    ],
-)
-
-proto_library(
-    name = "route_guide_proto",
-    srcs = ["protos/route_guide.proto"],
-)

examples/cpp/compression/BUILD

@@ -0,0 +1,35 @@
+# Copyright 2020 the 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.
+
+licenses(["notice"])  # 3-clause BSD
+
+cc_binary(
+    name = "compression_client",
+    srcs = ["greeter_client.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)
+
+cc_binary(
+    name = "compression_server",
+    srcs = ["greeter_server.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)

examples/cpp/helloworld/BUILD

@@ -0,0 +1,66 @@
+# Copyright 2020 the 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.
+
+licenses(["notice"])  # 3-clause BSD
+
+cc_binary(
+    name = "greeter_client",
+    srcs = ["greeter_client.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)
+
+cc_binary(
+    name = "greeter_async_client",
+    srcs = ["greeter_async_client.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)
+
+cc_binary(
+    name = "greeter_async_client2",
+    srcs = ["greeter_async_client2.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)
+
+cc_binary(
+    name = "greeter_server",
+    srcs = ["greeter_server.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//:grpc++_reflection",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)
+
+cc_binary(
+    name = "greeter_async_server",
+    srcs = ["greeter_async_server.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)

examples/cpp/keyvaluestore/BUILD

@@ -0,0 +1,38 @@
+# Copyright 2020 the 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.
+
+licenses(["notice"])  # 3-clause BSD
+
+cc_binary(
+    name = "keyvaluestore_client",
+    srcs = [
+        "caching_interceptor.h",
+        "client.cc",
+    ],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:keyvaluestore",
+    ],
+)
+
+cc_binary(
+    name = "keyvaluestore_server",
+    srcs = ["server.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:keyvaluestore",
+    ],
+)

examples/cpp/load_balancing/BUILD

@@ -0,0 +1,35 @@
+# Copyright 2020 the 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.
+
+licenses(["notice"])  # 3-clause BSD
+
+cc_binary(
+    name = "lb_server",
+    srcs = ["greeter_server.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)
+
+cc_binary(
+    name = "lb_client",
+    srcs = ["greeter_client.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)

examples/cpp/metadata/BUILD

@@ -0,0 +1,35 @@
+# Copyright 2020 the 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.
+
+licenses(["notice"])  # 3-clause BSD
+
+cc_binary(
+    name = "metadata_client",
+    srcs = ["greeter_client.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)
+
+cc_binary(
+    name = "metadata_server",
+    srcs = ["greeter_server.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+    ],
+)

examples/cpp/route_guide/BUILD

@@ -0,0 +1,56 @@
+# Copyright 2020 the 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.
+
+licenses(["notice"])  # 3-clause BSD
+
+cc_library(
+    name = "route_guide_helper",
+    srcs = [
+        "helper.cc",
+        "helper.h",
+    ],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:route_guide",
+    ],
+)
+
+cc_binary(
+    name = "route_guide_client",
+    srcs = [
+        "route_guide_client.cc",
+    ],
+    data = ["route_guide_db.json"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        ":route_guide_helper",
+        "//:grpc++",
+        "//examples/protos:route_guide",
+    ],
+)
+
+cc_binary(
+    name = "route_guide_server",
+    srcs = [
+        "route_guide_server.cc",
+    ],
+    data = ["route_guide_db.json"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        ":route_guide_helper",
+        "//:grpc++",
+        "//examples/protos:route_guide",
+    ],
+)

examples/node/xds/greeter_client.js

@@ -0,0 +1,62 @@
+/*
+ *
+ * Copyright 2015 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.
+ *
+ */
+
+var PROTO_PATH = __dirname + '/../../protos/helloworld.proto';
+
+var parseArgs = require('minimist');
+var grpc = require('@grpc/grpc-js');
+var grpc_xds = require('@grpc/grpc-js-xds');
+grpc_xds.register();
+
+var protoLoader = require('@grpc/proto-loader');
+var packageDefinition = protoLoader.loadSync(
+    PROTO_PATH,
+    {keepCase: true,
+     longs: String,
+     enums: String,
+     defaults: true,
+     oneofs: true
+    });
+var hello_proto = grpc.loadPackageDefinition(packageDefinition).helloworld;
+
+function main() {
+  var argv = parseArgs(process.argv.slice(2), {
+    string: 'target'
+  });
+  var target;
+  if (argv.target) {
+    target = argv.target;
+  } else {
+    target = 'localhost:50051';
+  }
+  var client = new hello_proto.Greeter(target,
+                                       grpc.credentials.createInsecure());
+  var user;
+  if (argv._.length > 0) {
+    user = argv._[0]; 
+  } else {
+    user = 'world';
+  }
+  client.sayHello({name: user}, function(err, response) {
+    if (err) throw err;
+    console.log('Greeting:', response.message);
+    client.close();
+  });
+}
+
+main();

examples/node/xds/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "grpc-examples-xds",
+  "version": "0.1.0",
+  "dependencies": {
+    "@grpc/proto-loader": "^0.5.0",
+    "@grpc/grpc-js": "^1.2.0",
+    "@grpc/grpc-js-xds": "^1.2.0",
+    "minimist": "^1.2.0"
+  }
+}

examples/objective-c/BUILD

@@ -22,17 +22,17 @@ load("@build_bazel_rules_apple//apple:macos.bzl", "macos_application")
 
 objc_grpc_library(
     name = "HelloWorld_grpc_proto",
-    srcs = ["//examples:protos/helloworld.proto"],
+    srcs = ["//examples/protos:helloworld.proto"],
     tags = ["manual"],
-    deps = ["//examples:helloworld_proto"],
+    deps = ["//examples/protos:helloworld_proto"],
 )
 
 # This one works with import "external/com_github_grpc_grpc/examples/protos/Keyvaluestore.pbrpc.h"
 objc_grpc_library(
     name = "Keyvaluestore_grpc_proto_external",
-    srcs = ["//external/com_github_grpc_grpc/examples:protos/keyvaluestore.proto"],
+    srcs = ["//external/com_github_grpc_grpc/examples/protos:keyvaluestore.proto"],
     tags = ["manual"],
-    deps = ["@com_github_grpc_grpc//examples:keyvaluestore_proto"],
+    deps = ["@com_github_grpc_grpc//examples/protos:keyvaluestore_proto"],
 )
 
 objc_library(
@@ -86,9 +86,9 @@ macos_application(
 
 objc_grpc_library(
     name = "RouteGuide",
-    srcs = ["//examples:protos/route_guide.proto"],
+    srcs = ["//examples/protos:route_guide.proto"],
     tags = ["manual"],
-    deps = ["//examples:route_guide_proto"],
+    deps = ["//examples/protos:route_guide_proto"],
 )
 
 objc_library(

examples/objective-c/helloworld/README.md

@@ -84,7 +84,7 @@ $ bazel build :HelloWorld
 #### Try it!
 To run the Hello World sample properly, we need a local server. Let's compile and run the corresponding C++ server:
 ```shell
-$ bazel run //examples:greeter_server
+$ bazel run //examples/cpp/helloworld:greeter_server
 ```
 
 To run the sample, you need to know the available simulator runtimes in your machine. You could either list the available runtimes yourself by running:

examples/protos/BUILD

@@ -0,0 +1,83 @@
+# Copyright 2020 the 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.
+
+licenses(["notice"])  # 3-clause BSD
+
+package(default_visibility = ["//visibility:public"])
+
+load("@grpc_python_dependencies//:requirements.bzl", "requirement")
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("//bazel:cc_grpc_library.bzl", "cc_grpc_library")
+load("//bazel:grpc_build_system.bzl", "grpc_proto_library")
+load("//bazel:python_rules.bzl", "py_grpc_library", "py_proto_library")
+
+grpc_proto_library(
+    name = "auth_sample",
+    srcs = ["auth_sample.proto"],
+)
+
+grpc_proto_library(
+    name = "hellostreamingworld",
+    srcs = ["hellostreamingworld.proto"],
+)
+
+# The following three rules demonstrate the usage of the cc_grpc_library rule in
+# in a mode compatible with the native proto_library and cc_proto_library rules.
+proto_library(
+    name = "helloworld_proto",
+    srcs = ["helloworld.proto"],
+)
+
+cc_proto_library(
+    name = "helloworld_cc_proto",
+    deps = [":helloworld_proto"],
+)
+
+cc_grpc_library(
+    name = "helloworld_cc_grpc",
+    srcs = [":helloworld_proto"],
+    grpc_only = True,
+    deps = [":helloworld_cc_proto"],
+)
+
+grpc_proto_library(
+    name = "route_guide",
+    srcs = ["route_guide.proto"],
+)
+
+proto_library(
+    name = "keyvaluestore_proto",
+    srcs = ["keyvaluestore.proto"],
+)
+
+grpc_proto_library(
+    name = "keyvaluestore",
+    srcs = ["keyvaluestore.proto"],
+)
+
+py_proto_library(
+    name = "helloworld_py_pb2",
+    deps = [":helloworld_proto"],
+)
+
+py_grpc_library(
+    name = "helloworld_py_pb2_grpc",
+    srcs = [":helloworld_proto"],
+    deps = [":helloworld_py_pb2"],
+)
+
+proto_library(
+    name = "route_guide_proto",
+    srcs = [":route_guide.proto"],
+)

examples/python/async_streaming/README.md

@@ -0,0 +1,50 @@
+# gRPC Python Non-Blocking Streaming RPC Client Example
+
+The goal of this example is to demonstrate how to handle streaming responses
+without blocking the current thread. Effectively, this can be achieved by
+converting the gRPC Python streaming API into callback-based.
+
+In this example, the RPC service `Phone` simulates the life cycle of virtual
+phone calls. It requires one thread to handle the phone-call session state
+changes, and another thread to process the audio stream. In this case, the
+normal blocking style API could not fulfill the need easily. Hence, we should
+asynchronously execute the streaming RPC.
+
+## Steps to run this example
+
+Start the server in one session
+```
+python3 server.py
+```
+
+Start the client in another session
+```
+python3 client.py
+```
+
+## Example Output
+```
+$ python3 server.py
+INFO:root:Server serving at [::]:50051
+INFO:root:Received a phone call request for number [1415926535]
+INFO:root:Created a call session [{
+  "sessionId": "0",
+  "media": "https://link.to.audio.resources"
+}]
+INFO:root:Call finished [1415926535]
+INFO:root:Call session cleaned [{
+  "sessionId": "0",
+  "media": "https://link.to.audio.resources"
+}]
+```
+
+```
+$ python3 client.py
+INFO:root:Waiting for peer to connect [1415926535]...
+INFO:root:Call toward [1415926535] enters [NEW] state
+INFO:root:Call toward [1415926535] enters [ACTIVE] state
+INFO:root:Consuming audio resource [https://link.to.audio.resources]
+INFO:root:Call toward [1415926535] enters [ENDED] state
+INFO:root:Audio session finished [https://link.to.audio.resources]
+INFO:root:Call finished!
+```

examples/python/async_streaming/client.py

@@ -0,0 +1,119 @@
+# Copyright 2020 The 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.
+
+import logging
+import threading
+from typing import Iterator
+from concurrent.futures import ThreadPoolExecutor
+
+import grpc
+
+import phone_pb2
+import phone_pb2_grpc
+
+
+class CallMaker:
+
+    def __init__(self, executor: ThreadPoolExecutor, channel: grpc.Channel,
+                 phone_number: str) -> None:
+        self._executor = executor
+        self._channel = channel
+        self._stub = phone_pb2_grpc.PhoneStub(self._channel)
+        self._phone_number = phone_number
+        self._session_id = None
+        self._audio_session_link = None
+        self._call_state = None
+        self._peer_responded = threading.Event()
+        self._call_finished = threading.Event()
+        self._consumer_future = None
+
+    def _response_watcher(
+            self,
+            response_iterator: Iterator[phone_pb2.StreamCallResponse]) -> None:
+        try:
+            for response in response_iterator:
+                # NOTE: All fields in Proto3 are optional. This is the recommended way
+                # to check if a field is present or not, or to exam which one-of field is
+                # fulfilled by this message.
+                if response.HasField("call_info"):
+                    self._on_call_info(response.call_info)
+                elif response.HasField("call_state"):
+                    self._on_call_state(response.call_state.state)
+                else:
+                    raise RuntimeError(
+                        "Received StreamCallResponse without call_info and call_state"
+                    )
+        except Exception as e:
+            self._peer_responded.set()
+            raise
+
+    def _on_call_info(self, call_info: phone_pb2.CallInfo) -> None:
+        self._session_id = call_info.session_id
+        self._audio_session_link = call_info.media
+
+    def _on_call_state(self, call_state: phone_pb2.CallState.State) -> None:
+        logging.info("Call toward [%s] enters [%s] state", self._phone_number,
+                     phone_pb2.CallState.State.Name(call_state))
+        self._call_state = call_state
+        if call_state is phone_pb2.CallState.State.ACTIVE:
+            self._peer_responded.set()
+        if call_state is phone_pb2.CallState.State.ENDED:
+            self._peer_responded.set()
+            self._call_finished.set()
+
+    def call(self) -> None:
+        request = phone_pb2.StreamCallRequest()
+        request.phone_number = self._phone_number
+        response_iterator = self._stub.StreamCall(iter((request,)))
+        # Instead of consuming the response on current thread, spawn a consumption thread.
+        self._consumer_future = self._executor.submit(self._response_watcher,
+                                                      response_iterator)
+
+    def wait_peer(self) -> None:
+        logging.info("Waiting for peer to connect [%s]...", self._phone_number)
+        self._peer_responded.wait(timeout=None)
+        if self._consumer_future.done():
+            # If the future raises, forwards the exception here
+            self._consumer_future.result()
+        return self._call_state is phone_pb2.CallState.State.ACTIVE
+
+    def audio_session(self) -> None:
+        assert self._audio_session_link is not None
+        logging.info("Consuming audio resource [%s]", self._audio_session_link)
+        self._call_finished.wait(timeout=None)
+        logging.info("Audio session finished [%s]", self._audio_session_link)
+
+
+def process_call(executor: ThreadPoolExecutor, channel: grpc.Channel,
+                 phone_number: str) -> None:
+    call_maker = CallMaker(executor, channel, phone_number)
+    call_maker.call()
+    if call_maker.wait_peer():
+        call_maker.audio_session()
+        logging.info("Call finished!")
+    else:
+        logging.info("Call failed: peer didn't answer")
+
+
+def run():
+    executor = ThreadPoolExecutor()
+    with grpc.insecure_channel("localhost:50051") as channel:
+        future = executor.submit(process_call, executor, channel,
+                                 "555-0100-XXXX")
+        future.result()
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+    run()

examples/python/async_streaming/phone.proto

@@ -0,0 +1,52 @@
+// Copyright 2020 The 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.
+
+syntax = "proto3";
+
+package grpc.testing;
+
+message CallInfo {
+  string session_id = 1;
+  string media = 2;
+}
+
+message CallState {
+  enum State {
+    // The default state.
+    UNDEFINED = 0;
+    // The call is newly created.
+    NEW = 1;
+    // The call is connected.
+    ACTIVE = 6;
+    // The call is finished.
+    ENDED = 7;
+  }
+  State state = 2;
+}
+
+message StreamCallRequest {
+  string phone_number = 1;
+}
+
+message StreamCallResponse {
+  oneof stream_call_response {
+    CallInfo call_info = 1;
+    CallState call_state = 2;
+  } 
+}
+
+service Phone {
+  // Makes a phone call and communicate states via a stream.
+  rpc StreamCall(stream StreamCallRequest) returns (stream StreamCallResponse);
+}

examples/python/async_streaming/phone_pb2.py

@@ -0,0 +1,267 @@
+# -*- coding: utf-8 -*-
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: phone.proto
+
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='phone.proto',
+  package='grpc.testing',
+  syntax='proto3',
+  serialized_options=None,
+  serialized_pb=b'\n\x0bphone.proto\x12\x0cgrpc.testing\"-\n\x08\x43\x61llInfo\x12\x12\n\nsession_id\x18\x01 \x01(\t\x12\r\n\x05media\x18\x02 \x01(\t\"q\n\tCallState\x12,\n\x05state\x18\x02 \x01(\x0e\x32\x1d.grpc.testing.CallState.State\"6\n\x05State\x12\r\n\tUNDEFINED\x10\x00\x12\x07\n\x03NEW\x10\x01\x12\n\n\x06\x41\x43TIVE\x10\x06\x12\t\n\x05\x45NDED\x10\x07\")\n\x11StreamCallRequest\x12\x14\n\x0cphone_number\x18\x01 \x01(\t\"\x88\x01\n\x12StreamCallResponse\x12+\n\tcall_info\x18\x01 \x01(\x0b\x32\x16.grpc.testing.CallInfoH\x00\x12-\n\ncall_state\x18\x02 \x01(\x0b\x32\x17.grpc.testing.CallStateH\x00\x42\x16\n\x14stream_call_response2\\\n\x05Phone\x12S\n\nStreamCall\x12\x1f.grpc.testing.StreamCallRequest\x1a .grpc.testing.StreamCallResponse(\x01\x30\x01\x62\x06proto3'
+)
+
+
+
+_CALLSTATE_STATE = _descriptor.EnumDescriptor(
+  name='State',
+  full_name='grpc.testing.CallState.State',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
+      name='UNDEFINED', index=0, number=0,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='NEW', index=1, number=1,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='ACTIVE', index=2, number=6,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='ENDED', index=3, number=7,
+      serialized_options=None,
+      type=None),
+  ],
+  containing_type=None,
+  serialized_options=None,
+  serialized_start=135,
+  serialized_end=189,
+)
+_sym_db.RegisterEnumDescriptor(_CALLSTATE_STATE)
+
+
+_CALLINFO = _descriptor.Descriptor(
+  name='CallInfo',
+  full_name='grpc.testing.CallInfo',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='session_id', full_name='grpc.testing.CallInfo.session_id', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=b"".decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='media', full_name='grpc.testing.CallInfo.media', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=b"".decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=29,
+  serialized_end=74,
+)
+
+
+_CALLSTATE = _descriptor.Descriptor(
+  name='CallState',
+  full_name='grpc.testing.CallState',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='state', full_name='grpc.testing.CallState.state', index=0,
+      number=2, type=14, cpp_type=8, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+    _CALLSTATE_STATE,
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=76,
+  serialized_end=189,
+)
+
+
+_STREAMCALLREQUEST = _descriptor.Descriptor(
+  name='StreamCallRequest',
+  full_name='grpc.testing.StreamCallRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='phone_number', full_name='grpc.testing.StreamCallRequest.phone_number', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=b"".decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=191,
+  serialized_end=232,
+)
+
+
+_STREAMCALLRESPONSE = _descriptor.Descriptor(
+  name='StreamCallResponse',
+  full_name='grpc.testing.StreamCallResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='call_info', full_name='grpc.testing.StreamCallResponse.call_info', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='call_state', full_name='grpc.testing.StreamCallResponse.call_state', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+    _descriptor.OneofDescriptor(
+      name='stream_call_response', full_name='grpc.testing.StreamCallResponse.stream_call_response',
+      index=0, containing_type=None, fields=[]),
+  ],
+  serialized_start=235,
+  serialized_end=371,
+)
+
+_CALLSTATE.fields_by_name['state'].enum_type = _CALLSTATE_STATE
+_CALLSTATE_STATE.containing_type = _CALLSTATE
+_STREAMCALLRESPONSE.fields_by_name['call_info'].message_type = _CALLINFO
+_STREAMCALLRESPONSE.fields_by_name['call_state'].message_type = _CALLSTATE
+_STREAMCALLRESPONSE.oneofs_by_name['stream_call_response'].fields.append(
+  _STREAMCALLRESPONSE.fields_by_name['call_info'])
+_STREAMCALLRESPONSE.fields_by_name['call_info'].containing_oneof = _STREAMCALLRESPONSE.oneofs_by_name['stream_call_response']
+_STREAMCALLRESPONSE.oneofs_by_name['stream_call_response'].fields.append(
+  _STREAMCALLRESPONSE.fields_by_name['call_state'])
+_STREAMCALLRESPONSE.fields_by_name['call_state'].containing_oneof = _STREAMCALLRESPONSE.oneofs_by_name['stream_call_response']
+DESCRIPTOR.message_types_by_name['CallInfo'] = _CALLINFO
+DESCRIPTOR.message_types_by_name['CallState'] = _CALLSTATE
+DESCRIPTOR.message_types_by_name['StreamCallRequest'] = _STREAMCALLREQUEST
+DESCRIPTOR.message_types_by_name['StreamCallResponse'] = _STREAMCALLRESPONSE
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+CallInfo = _reflection.GeneratedProtocolMessageType('CallInfo', (_message.Message,), {
+  'DESCRIPTOR' : _CALLINFO,
+  '__module__' : 'phone_pb2'
+  # @@protoc_insertion_point(class_scope:grpc.testing.CallInfo)
+  })
+_sym_db.RegisterMessage(CallInfo)
+
+CallState = _reflection.GeneratedProtocolMessageType('CallState', (_message.Message,), {
+  'DESCRIPTOR' : _CALLSTATE,
+  '__module__' : 'phone_pb2'
+  # @@protoc_insertion_point(class_scope:grpc.testing.CallState)
+  })
+_sym_db.RegisterMessage(CallState)
+
+StreamCallRequest = _reflection.GeneratedProtocolMessageType('StreamCallRequest', (_message.Message,), {
+  'DESCRIPTOR' : _STREAMCALLREQUEST,
+  '__module__' : 'phone_pb2'
+  # @@protoc_insertion_point(class_scope:grpc.testing.StreamCallRequest)
+  })
+_sym_db.RegisterMessage(StreamCallRequest)
+
+StreamCallResponse = _reflection.GeneratedProtocolMessageType('StreamCallResponse', (_message.Message,), {
+  'DESCRIPTOR' : _STREAMCALLRESPONSE,
+  '__module__' : 'phone_pb2'
+  # @@protoc_insertion_point(class_scope:grpc.testing.StreamCallResponse)
+  })
+_sym_db.RegisterMessage(StreamCallResponse)
+
+
+
+_PHONE = _descriptor.ServiceDescriptor(
+  name='Phone',
+  full_name='grpc.testing.Phone',
+  file=DESCRIPTOR,
+  index=0,
+  serialized_options=None,
+  serialized_start=373,
+  serialized_end=465,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='StreamCall',
+    full_name='grpc.testing.Phone.StreamCall',
+    index=0,
+    containing_service=None,
+    input_type=_STREAMCALLREQUEST,
+    output_type=_STREAMCALLRESPONSE,
+    serialized_options=None,
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_PHONE)
+
+DESCRIPTOR.services_by_name['Phone'] = _PHONE
+
+# @@protoc_insertion_point(module_scope)

examples/python/async_streaming/phone_pb2_grpc.py

@@ -0,0 +1,65 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+import phone_pb2 as phone__pb2
+
+
+class PhoneStub(object):
+    """Missing associated documentation comment in .proto file"""
+
+    def __init__(self, channel):
+        """Constructor.
+
+        Args:
+            channel: A grpc.Channel.
+        """
+        self.StreamCall = channel.stream_stream(
+                '/grpc.testing.Phone/StreamCall',
+                request_serializer=phone__pb2.StreamCallRequest.SerializeToString,
+                response_deserializer=phone__pb2.StreamCallResponse.FromString,
+                )
+
+
+class PhoneServicer(object):
+    """Missing associated documentation comment in .proto file"""
+
+    def StreamCall(self, request_iterator, context):
+        """Makes a phone call and communicate states via a stream.
+        """
+        context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+        context.set_details('Method not implemented!')
+        raise NotImplementedError('Method not implemented!')
+
+
+def add_PhoneServicer_to_server(servicer, server):
+    rpc_method_handlers = {
+            'StreamCall': grpc.stream_stream_rpc_method_handler(
+                    servicer.StreamCall,
+                    request_deserializer=phone__pb2.StreamCallRequest.FromString,
+                    response_serializer=phone__pb2.StreamCallResponse.SerializeToString,
+            ),
+    }
+    generic_handler = grpc.method_handlers_generic_handler(
+            'grpc.testing.Phone', rpc_method_handlers)
+    server.add_generic_rpc_handlers((generic_handler,))
+
+
+ # This class is part of an EXPERIMENTAL API.
+class Phone(object):
+    """Missing associated documentation comment in .proto file"""
+
+    @staticmethod
+    def StreamCall(request_iterator,
+            target,
+            options=(),
+            channel_credentials=None,
+            call_credentials=None,
+            compression=None,
+            wait_for_ready=None,
+            timeout=None,
+            metadata=None):
+        return grpc.experimental.stream_stream(request_iterator, target, '/grpc.testing.Phone/StreamCall',
+            phone__pb2.StreamCallRequest.SerializeToString,
+            phone__pb2.StreamCallResponse.FromString,
+            options, channel_credentials,
+            call_credentials, compression, wait_for_ready, timeout, metadata)

examples/python/async_streaming/server.py

@@ -0,0 +1,92 @@
+# Copyright 2020 The 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.
+
+import logging
+import time
+from concurrent.futures import ThreadPoolExecutor
+from typing import Iterable
+import threading
+
+import grpc
+from google.protobuf.json_format import MessageToJson
+
+import phone_pb2
+import phone_pb2_grpc
+
+
+def create_state_response(call_state: phone_pb2.CallState.State
+                         ) -> phone_pb2.StreamCallResponse:
+    response = phone_pb2.StreamCallResponse()
+    response.call_state.state = call_state
+    return response
+
+
+class Phone(phone_pb2_grpc.PhoneServicer):
+
+    def __init__(self):
+        self._id_counter = 0
+        self._lock = threading.RLock()
+
+    def _create_call_session(self) -> phone_pb2.CallInfo:
+        call_info = phone_pb2.CallInfo()
+        with self._lock:
+            call_info.session_id = str(self._id_counter)
+            self._id_counter += 1
+        call_info.media = "https://link.to.audio.resources"
+        logging.info("Created a call session [%s]", MessageToJson(call_info))
+        return call_info
+
+    def _clean_call_session(self, call_info: phone_pb2.CallInfo) -> None:
+        logging.info("Call session cleaned [%s]", MessageToJson(call_info))
+
+    def StreamCall(self,
+                   request_iterator: Iterable[phone_pb2.StreamCallRequest],
+                   context: grpc.ServicerContext
+                  ) -> Iterable[phone_pb2.StreamCallResponse]:
+        try:
+            request = next(request_iterator)
+            logging.info("Received a phone call request for number [%s]",
+                         request.phone_number)
+        except StopIteration:
+            raise RuntimeError("Failed to receive call request")
+        # Simulate the acceptance of call request
+        time.sleep(1)
+        yield create_state_response(phone_pb2.CallState.NEW)
+        # Simulate the start of the call session
+        time.sleep(1)
+        call_info = self._create_call_session()
+        context.add_callback(lambda: self._clean_call_session(call_info))
+        response = phone_pb2.StreamCallResponse()
+        response.call_info.session_id = call_info.session_id
+        response.call_info.media = call_info.media
+        yield response
+        yield create_state_response(phone_pb2.CallState.ACTIVE)
+        # Simulate the end of the call
+        time.sleep(2)
+        yield create_state_response(phone_pb2.CallState.ENDED)
+        logging.info("Call finished [%s]", request.phone_number)
+
+
+def serve(address: str) -> None:
+    server = grpc.server(ThreadPoolExecutor())
+    phone_pb2_grpc.add_PhoneServicer_to_server(Phone(), server)
+    server.add_insecure_port(address)
+    server.start()
+    logging.info("Server serving at %s", address)
+    server.wait_for_termination()
+
+
+if __name__ == "__main__":
+    logging.basicConfig(level=logging.INFO)
+    serve("[::]:50051")

examples/python/compression/BUILD.bazel

@@ -18,8 +18,8 @@ py_binary(
     python_version = "PY3",
     srcs_version = "PY2AND3",
     deps = [
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
+        "//examples/protos:helloworld_py_pb2",
+        "//examples/protos:helloworld_py_pb2_grpc",
         "//src/python/grpcio/grpc:grpcio",
     ],
 )
@@ -30,8 +30,8 @@ py_binary(
     python_version = "PY3",
     srcs_version = "PY2AND3",
     deps = [
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
+        "//examples/protos:helloworld_py_pb2",
+        "//examples/protos:helloworld_py_pb2_grpc",
         "//src/python/grpcio/grpc:grpcio",
     ],
 )

examples/python/compression/client.py

@@ -21,8 +21,8 @@ import argparse
 import logging
 import grpc
 
-from examples import helloworld_pb2
-from examples import helloworld_pb2_grpc
+from examples.protos import helloworld_pb2
+from examples.protos import helloworld_pb2_grpc
 
 _DESCRIPTION = 'A client capable of compression.'
 _COMPRESSION_OPTIONS = {

examples/python/compression/server.py

@@ -23,8 +23,8 @@ import logging
 import threading
 import grpc
 
-from examples import helloworld_pb2
-from examples import helloworld_pb2_grpc
+from examples.protos import helloworld_pb2
+from examples.protos import helloworld_pb2_grpc
 
 _DESCRIPTION = 'A server capable of compression.'
 _COMPRESSION_OPTIONS = {

examples/python/debug/BUILD.bazel

@@ -14,33 +14,35 @@
 
 load("@grpc_python_dependencies//:requirements.bzl", "requirement")
 
+package(default_testonly = 1)
+
 py_binary(
     name = "debug_server",
-    testonly = 1,
     srcs = ["debug_server.py"],
+    data = ["helloworld.proto"],
+    imports = ["."],
+    python_version = "PY3",
     deps = [
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
         "//src/python/grpcio/grpc:grpcio",
         "//src/python/grpcio_channelz/grpc_channelz/v1:grpc_channelz",
+        "//tools/distrib/python/grpcio_tools:grpc_tools",
     ],
 )
 
 py_binary(
     name = "send_message",
-    testonly = 1,
     srcs = ["send_message.py"],
+    data = ["helloworld.proto"],
+    imports = ["."],
     python_version = "PY3",
     deps = [
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
         "//src/python/grpcio/grpc:grpcio",
+        "//tools/distrib/python/grpcio_tools:grpc_tools",
     ],
 )
 
 py_binary(
     name = "get_stats",
-    testonly = 1,
     srcs = ["get_stats.py"],
     python_version = "PY3",
     deps = [
@@ -49,17 +51,52 @@ py_binary(
     ],
 )
 
+py_binary(
+    name = "asyncio_debug_server",
+    srcs = ["asyncio_debug_server.py"],
+    data = ["helloworld.proto"],
+    imports = ["."],
+    python_version = "PY3",
+    deps = [
+        "//src/python/grpcio/grpc:grpcio",
+        "//src/python/grpcio_channelz/grpc_channelz/v1:grpc_channelz",
+        "//tools/distrib/python/grpcio_tools:grpc_tools",
+    ],
+)
+
+py_binary(
+    name = "asyncio_send_message",
+    srcs = ["asyncio_send_message.py"],
+    data = ["helloworld.proto"],
+    imports = ["."],
+    python_version = "PY3",
+    deps = [
+        "//src/python/grpcio/grpc:grpcio",
+        "//tools/distrib/python/grpcio_tools:grpc_tools",
+    ],
+)
+
+py_binary(
+    name = "asyncio_get_stats",
+    srcs = ["asyncio_get_stats.py"],
+    python_version = "PY3",
+    deps = [
+        "//src/python/grpcio/grpc:grpcio",
+        "//src/python/grpcio_channelz/grpc_channelz/v1:grpc_channelz",
+    ],
+)
+
 py_test(
     name = "_debug_example_test",
     srcs = ["test/_debug_example_test.py"],
+    imports = ["."],
     python_version = "PY3",
     deps = [
+        ":asyncio_debug_server",
+        ":asyncio_get_stats",
+        ":asyncio_send_message",
         ":debug_server",
         ":get_stats",
         ":send_message",
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
-        "//src/python/grpcio/grpc:grpcio",
-        "//src/python/grpcio_channelz/grpc_channelz/v1:grpc_channelz",
     ],
 )

examples/python/debug/asyncio_debug_server.py

@@ -0,0 +1,83 @@
+# Copyright 2020 The 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 AsyncIO example of utilizing Channelz feature."""
+
+import asyncio
+import argparse
+import logging
+import random
+
+import grpc
+
+helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
+    "helloworld.proto")
+
+# TODO: Suppress until the macOS segfault fix rolled out
+from grpc_channelz.v1 import channelz  # pylint: disable=wrong-import-position
+
+_LOGGER = logging.getLogger(__name__)
+_LOGGER.setLevel(logging.INFO)
+
+_RANDOM_FAILURE_RATE = 0.3
+
+
+class FaultInjectGreeter(helloworld_pb2_grpc.GreeterServicer):
+
+    def __init__(self, failure_rate):
+        self._failure_rate = failure_rate
+
+    async def SayHello(self, request: helloworld_pb2.HelloRequest,
+                       context: grpc.aio.ServicerContext
+                      ) -> helloworld_pb2.HelloReply:
+        if random.random() < self._failure_rate:
+            context.abort(grpc.StatusCode.UNAVAILABLE,
+                          'Randomly injected failure.')
+        return helloworld_pb2.HelloReply(message=f'Hello, {request.name}!')
+
+
+def create_server(addr: str, failure_rate: float) -> grpc.aio.Server:
+    server = grpc.aio.server()
+    helloworld_pb2_grpc.add_GreeterServicer_to_server(
+        FaultInjectGreeter(failure_rate), server)
+
+    # Add Channelz Servicer to the gRPC server
+    channelz.add_channelz_servicer(server)
+
+    server.add_insecure_port(addr)
+    return server
+
+
+async def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--addr',
+                        nargs=1,
+                        type=str,
+                        default='[::]:50051',
+                        help='the address to listen on')
+    parser.add_argument(
+        '--failure_rate',
+        nargs=1,
+        type=float,
+        default=0.3,
+        help='a float indicates the percentage of failed message injections')
+    args = parser.parse_args()
+
+    server = create_server(addr=args.addr, failure_rate=args.failure_rate)
+    await server.start()
+    await server.wait_for_termination()
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+    asyncio.get_event_loop().run_until_complete(main())

examples/python/debug/asyncio_get_stats.py

@@ -0,0 +1,46 @@
+# Copyright 2020 The 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.
+"""Poll statistics from the server."""
+
+import asyncio
+import logging
+import argparse
+import grpc
+
+from grpc_channelz.v1 import channelz_pb2
+from grpc_channelz.v1 import channelz_pb2_grpc
+
+
+async def run(addr: str) -> None:
+    async with grpc.aio.insecure_channel(addr) as channel:
+        channelz_stub = channelz_pb2_grpc.ChannelzStub(channel)
+        response = await channelz_stub.GetServers(
+            channelz_pb2.GetServersRequest(start_server_id=0))
+        print('Info for all servers: %s' % response)
+
+
+async def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--addr',
+                        nargs=1,
+                        type=str,
+                        default='[::]:50051',
+                        help='the address to request')
+    args = parser.parse_args()
+    run(addr=args.addr)
+
+
+if __name__ == '__main__':
+    logging.basicConfig()
+    asyncio.get_event_loop().run_until_complete(main())

examples/python/debug/asyncio_send_message.py

@@ -0,0 +1,61 @@
+# Copyright 2020 The 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.
+"""Send multiple greeting messages to the backend."""
+
+import asyncio
+import logging
+import argparse
+import grpc
+
+helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
+    "helloworld.proto")
+
+
+async def process(stub: helloworld_pb2_grpc.GreeterStub,
+                  request: helloworld_pb2.HelloRequest) -> None:
+    try:
+        response = await stub.SayHello(request)
+    except grpc.aio.AioRpcError as rpc_error:
+        print(f'Received error: {rpc_error}')
+    else:
+        print(f'Received message: {response}')
+
+
+async def run(addr: str, n: int) -> None:
+    async with grpc.aio.insecure_channel(addr) as channel:
+        stub = helloworld_pb2_grpc.GreeterStub(channel)
+        request = helloworld_pb2.HelloRequest(name='you')
+        for _ in range(n):
+            await process(stub, request)
+
+
+async def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--addr',
+                        nargs=1,
+                        type=str,
+                        default='[::]:50051',
+                        help='the address to request')
+    parser.add_argument('-n',
+                        nargs=1,
+                        type=int,
+                        default=10,
+                        help='an integer for number of messages to sent')
+    args = parser.parse_args()
+    await run(addr=args.addr, n=args.n)
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+    asyncio.get_event_loop().run_until_complete(main())

examples/python/debug/debug_server.py

@@ -23,10 +23,12 @@ from concurrent import futures
 import random
 
 import grpc
-from grpc_channelz.v1 import channelz
 
-from examples import helloworld_pb2
-from examples import helloworld_pb2_grpc
+helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
+    "helloworld.proto")
+
+# TODO: Suppress until the macOS segfault fix rolled out
+from grpc_channelz.v1 import channelz  # pylint: disable=wrong-import-position
 
 _LOGGER = logging.getLogger(__name__)
 _LOGGER.setLevel(logging.INFO)

examples/python/debug/get_stats.py

@@ -28,9 +28,11 @@ from grpc_channelz.v1 import channelz_pb2_grpc
 def run(addr):
     with grpc.insecure_channel(addr) as channel:
         channelz_stub = channelz_pb2_grpc.ChannelzStub(channel)
-        response = channelz_stub.GetServers(
-            channelz_pb2.GetServersRequest(start_server_id=0))
-        print('Info for all servers: %s' % response)
+        # This RPC pulls server-level metrics, like sent/received messages,
+        # succeeded/failed RPCs. For more info see:
+        # https://github.com/grpc/grpc/blob/master/src/proto/grpc/channelz/channelz.proto
+        response = channelz_stub.GetServers(channelz_pb2.GetServersRequest())
+        print(f'Info for all servers: {response}')
 
 
 def main():

examples/python/debug/helloworld.proto

@@ -0,0 +1 @@
+../../protos/helloworld.proto

examples/python/debug/send_message.py

@@ -20,8 +20,9 @@ from __future__ import print_function
 import logging
 import argparse
 import grpc
-from examples import helloworld_pb2
-from examples import helloworld_pb2_grpc
+
+helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
+    "helloworld.proto")
 
 
 def process(stub, request):

examples/python/debug/test/_debug_example_test.py

@@ -13,16 +13,16 @@
 # limitations under the License.
 """Test for gRPC Python debug example."""
 
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
-
+import asyncio
 import logging
 import unittest
 
 from examples.python.debug import debug_server
+from examples.python.debug import asyncio_debug_server
 from examples.python.debug import send_message
+from examples.python.debug import asyncio_send_message
 from examples.python.debug import get_stats
+from examples.python.debug import asyncio_get_stats
 
 _LOGGER = logging.getLogger(__name__)
 _LOGGER.setLevel(logging.INFO)
@@ -47,7 +47,23 @@ class DebugExampleTest(unittest.TestCase):
         server.stop(None)
         # No unhandled exception raised, test passed!
 
+    def test_asyncio_channelz_example(self):
+
+        async def body():
+            server = asyncio_debug_server.create_server(
+                addr='[::]:0', failure_rate=_FAILURE_RATE)
+            port = server.add_insecure_port('[::]:0')
+            await server.start()
+            address = _ADDR_TEMPLATE % port
+
+            await asyncio_send_message.run(addr=address, n=_NUMBER_OF_MESSAGES)
+            await asyncio_get_stats.run(addr=address)
+            await server.stop(None)
+            # No unhandled exception raised, test passed!
+
+        asyncio.get_event_loop().run_until_complete(body())
+
 
 if __name__ == '__main__':
-    logging.basicConfig()
+    logging.basicConfig(level=logging.DEBUG)
     unittest.main(verbosity=2)

examples/python/errors/BUILD.bazel

@@ -19,8 +19,8 @@ py_library(
     testonly = 1,
     srcs = ["client.py"],
     deps = [
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
+        "//examples/protos:helloworld_py_pb2",
+        "//examples/protos:helloworld_py_pb2_grpc",
         "//src/python/grpcio/grpc:grpcio",
         "//src/python/grpcio_status/grpc_status",
         requirement("googleapis-common-protos"),
@@ -34,8 +34,8 @@ py_library(
     deps = [
         "//src/python/grpcio/grpc:grpcio",
         "//src/python/grpcio_status/grpc_status:grpc_status",
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
+        "//examples/protos:helloworld_py_pb2",
+        "//examples/protos:helloworld_py_pb2_grpc",
     ] + select({
         "//conditions:default": [requirement("futures")],
         "//:python3": [],

examples/python/errors/client.py

@@ -20,8 +20,8 @@ import grpc
 from grpc_status import rpc_status
 from google.rpc import error_details_pb2
 
-from examples import helloworld_pb2
-from examples import helloworld_pb2_grpc
+from examples.protos import helloworld_pb2
+from examples.protos import helloworld_pb2_grpc
 
 _LOGGER = logging.getLogger(__name__)
 

examples/python/errors/server.py

@@ -23,8 +23,8 @@ from grpc_status import rpc_status
 from google.protobuf import any_pb2
 from google.rpc import code_pb2, status_pb2, error_details_pb2
 
-from examples import helloworld_pb2
-from examples import helloworld_pb2_grpc
+from examples.protos import helloworld_pb2
+from examples.protos import helloworld_pb2_grpc
 
 
 def create_greet_limit_exceed_error_status(name):

examples/python/errors/test/_error_handling_example_test.py

@@ -26,7 +26,7 @@ import logging
 
 import grpc
 
-from examples import helloworld_pb2_grpc
+from examples.protos import helloworld_pb2_grpc
 from examples.python.errors import client as error_handling_client
 from examples.python.errors import server as error_handling_server
 

examples/python/route_guide/asyncio_route_guide_client.py

@@ -0,0 +1,129 @@
+# Copyright 2020 The 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 AsyncIO implementation of the gRPC route guide client."""
+
+import asyncio
+import random
+import logging
+from typing import List, Iterable
+
+import grpc
+
+import route_guide_pb2
+import route_guide_pb2_grpc
+import route_guide_resources
+
+
+def make_route_note(message: str, latitude: int,
+                    longitude: int) -> route_guide_pb2.RouteNote:
+    return route_guide_pb2.RouteNote(
+        message=message,
+        location=route_guide_pb2.Point(latitude=latitude, longitude=longitude))
+
+
+# Performs an unary call
+async def guide_get_one_feature(stub: route_guide_pb2_grpc.RouteGuideStub,
+                                point: route_guide_pb2.Point) -> None:
+    feature = await stub.GetFeature(point)
+    if not feature.location:
+        print("Server returned incomplete feature")
+        return
+
+    if feature.name:
+        print(f"Feature called {feature.name} at {feature.location}")
+    else:
+        print(f"Found no feature at {feature.location}")
+
+
+async def guide_get_feature(stub: route_guide_pb2_grpc.RouteGuideStub) -> None:
+    await guide_get_one_feature(
+        stub, route_guide_pb2.Point(latitude=409146138, longitude=-746188906))
+    await guide_get_one_feature(stub,
+                                route_guide_pb2.Point(latitude=0, longitude=0))
+
+
+# Performs a server-streaming call
+async def guide_list_features(stub: route_guide_pb2_grpc.RouteGuideStub
+                             ) -> None:
+    rectangle = route_guide_pb2.Rectangle(
+        lo=route_guide_pb2.Point(latitude=400000000, longitude=-750000000),
+        hi=route_guide_pb2.Point(latitude=420000000, longitude=-730000000))
+    print("Looking for features between 40, -75 and 42, -73")
+
+    features = stub.ListFeatures(rectangle)
+
+    async for feature in features:
+        print(f"Feature called {feature.name} at {feature.location}")
+
+
+def generate_route(feature_list: List[route_guide_pb2.Feature]
+                  ) -> Iterable[route_guide_pb2.Point]:
+    for _ in range(0, 10):
+        random_feature = random.choice(feature_list)
+        print(f"Visiting point {random_feature.location}")
+        yield random_feature.location
+
+
+# Performs a client-streaming call
+async def guide_record_route(stub: route_guide_pb2_grpc.RouteGuideStub) -> None:
+    feature_list = route_guide_resources.read_route_guide_database()
+    route_iterator = generate_route(feature_list)
+
+    # gRPC AsyncIO client-streaming RPC API accepts both synchronous iterables
+    # and async iterables.
+    route_summary = await stub.RecordRoute(route_iterator)
+    print(f"Finished trip with {route_summary.point_count} points")
+    print(f"Passed {route_summary.feature_count} features")
+    print(f"Travelled {route_summary.distance} meters")
+    print(f"It took {route_summary.elapsed_time} seconds")
+
+
+def generate_messages() -> Iterable[route_guide_pb2.RouteNote]:
+    messages = [
+        make_route_note("First message", 0, 0),
+        make_route_note("Second message", 0, 1),
+        make_route_note("Third message", 1, 0),
+        make_route_note("Fourth message", 0, 0),
+        make_route_note("Fifth message", 1, 0),
+    ]
+    for msg in messages:
+        print(f"Sending {msg.message} at {msg.location}")
+        yield msg
+
+
+# Performs a bidi-streaming call
+async def guide_route_chat(stub: route_guide_pb2_grpc.RouteGuideStub) -> None:
+    # gRPC AsyncIO bidi-streaming RPC API accepts both synchronous iterables
+    # and async iterables.
+    call = stub.RouteChat(generate_messages())
+    async for response in call:
+        print(f"Received message {response.message} at {response.location}")
+
+
+async def main() -> None:
+    async with grpc.aio.insecure_channel('localhost:50051') as channel:
+        stub = route_guide_pb2_grpc.RouteGuideStub(channel)
+        print("-------------- GetFeature --------------")
+        await guide_get_feature(stub)
+        print("-------------- ListFeatures --------------")
+        await guide_list_features(stub)
+        print("-------------- RecordRoute --------------")
+        await guide_record_route(stub)
+        print("-------------- RouteChat --------------")
+        await guide_route_chat(stub)
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+    asyncio.get_event_loop().run_until_complete(main())

examples/python/route_guide/asyncio_route_guide_server.py

@@ -0,0 +1,134 @@
+# Copyright 2020 The 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 AsyncIO implementation of the gRPC route guide server."""
+
+import asyncio
+import time
+import math
+import logging
+from typing import AsyncIterable, Iterable
+
+import grpc
+
+import route_guide_pb2
+import route_guide_pb2_grpc
+import route_guide_resources
+
+
+def get_feature(feature_db: Iterable[route_guide_pb2.Feature],
+                point: route_guide_pb2.Point) -> route_guide_pb2.Feature:
+    """Returns Feature at given location or None."""
+    for feature in feature_db:
+        if feature.location == point:
+            return feature
+    return None
+
+
+def get_distance(start: route_guide_pb2.Point,
+                 end: route_guide_pb2.Point) -> float:
+    """Distance between two points."""
+    coord_factor = 10000000.0
+    lat_1 = start.latitude / coord_factor
+    lat_2 = end.latitude / coord_factor
+    lon_1 = start.longitude / coord_factor
+    lon_2 = end.longitude / coord_factor
+    lat_rad_1 = math.radians(lat_1)
+    lat_rad_2 = math.radians(lat_2)
+    delta_lat_rad = math.radians(lat_2 - lat_1)
+    delta_lon_rad = math.radians(lon_2 - lon_1)
+
+    # Formula is based on http://mathforum.org/library/drmath/view/51879.html
+    a = (pow(math.sin(delta_lat_rad / 2), 2) +
+         (math.cos(lat_rad_1) * math.cos(lat_rad_2) *
+          pow(math.sin(delta_lon_rad / 2), 2)))
+    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))
+    R = 6371000
+    # metres
+    return R * c
+
+
+class RouteGuideServicer(route_guide_pb2_grpc.RouteGuideServicer):
+    """Provides methods that implement functionality of route guide server."""
+
+    def __init__(self) -> None:
+        self.db = route_guide_resources.read_route_guide_database()
+
+    def GetFeature(self, request: route_guide_pb2.Point,
+                   unused_context) -> route_guide_pb2.Feature:
+        feature = get_feature(self.db, request)
+        if feature is None:
+            return route_guide_pb2.Feature(name="", location=request)
+        else:
+            return feature
+
+    async def ListFeatures(self, request: route_guide_pb2.Rectangle,
+                           unused_context
+                          ) -> AsyncIterable[route_guide_pb2.Feature]:
+        left = min(request.lo.longitude, request.hi.longitude)
+        right = max(request.lo.longitude, request.hi.longitude)
+        top = max(request.lo.latitude, request.hi.latitude)
+        bottom = min(request.lo.latitude, request.hi.latitude)
+        for feature in self.db:
+            if (feature.location.longitude >= left and
+                    feature.location.longitude <= right and
+                    feature.location.latitude >= bottom and
+                    feature.location.latitude <= top):
+                yield feature
+
+    async def RecordRoute(
+            self, request_iterator: AsyncIterable[route_guide_pb2.Point],
+            unused_context) -> route_guide_pb2.RouteSummary:
+        point_count = 0
+        feature_count = 0
+        distance = 0.0
+        prev_point = None
+
+        start_time = time.time()
+        async for point in request_iterator:
+            point_count += 1
+            if get_feature(self.db, point):
+                feature_count += 1
+            if prev_point:
+                distance += get_distance(prev_point, point)
+            prev_point = point
+
+        elapsed_time = time.time() - start_time
+        return route_guide_pb2.RouteSummary(point_count=point_count,
+                                            feature_count=feature_count,
+                                            distance=int(distance),
+                                            elapsed_time=int(elapsed_time))
+
+    async def RouteChat(
+            self, request_iterator: AsyncIterable[route_guide_pb2.RouteNote],
+            unused_context) -> AsyncIterable[route_guide_pb2.RouteNote]:
+        prev_notes = []
+        async for new_note in request_iterator:
+            for prev_note in prev_notes:
+                if prev_note.location == new_note.location:
+                    yield prev_note
+            prev_notes.append(new_note)
+
+
+async def serve() -> None:
+    server = grpc.aio.server()
+    route_guide_pb2_grpc.add_RouteGuideServicer_to_server(
+        RouteGuideServicer(), server)
+    server.add_insecure_port('[::]:50051')
+    await server.start()
+    await server.wait_for_termination()
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+    asyncio.get_event_loop().run_until_complete(serve())

examples/python/wait_for_ready/BUILD.bazel

@@ -14,14 +14,29 @@
 
 load("@grpc_python_dependencies//:requirements.bzl", "requirement")
 
-py_library(
+package(default_testonly = 1)
+
+py_binary(
     name = "wait_for_ready_example",
-    testonly = 1,
     srcs = ["wait_for_ready_example.py"],
+    data = ["helloworld.proto"],
+    imports = ["."],
+    python_version = "PY3",
+    deps = [
+        "//src/python/grpcio/grpc:grpcio",
+        "//tools/distrib/python/grpcio_tools:grpc_tools",
+    ],
+)
+
+py_binary(
+    name = "asyncio_wait_for_ready_example",
+    srcs = ["asyncio_wait_for_ready_example.py"],
+    data = ["helloworld.proto"],
+    imports = ["."],
+    python_version = "PY3",
     deps = [
-        "//examples:helloworld_py_pb2",
-        "//examples:helloworld_py_pb2_grpc",
         "//src/python/grpcio/grpc:grpcio",
+        "//tools/distrib/python/grpcio_tools:grpc_tools",
     ],
 )
 
@@ -30,5 +45,8 @@ py_test(
     size = "small",
     srcs = ["test/_wait_for_ready_example_test.py"],
     python_version = "PY3",
-    deps = [":wait_for_ready_example"],
+    deps = [
+        ":asyncio_wait_for_ready_example",
+        ":wait_for_ready_example",
+    ],
 )

examples/python/wait_for_ready/asyncio_wait_for_ready_example.py

@@ -0,0 +1,109 @@
+# Copyright 2020 The 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 example of utilizing wait-for-ready flag."""
+
+import asyncio
+import logging
+from contextlib import contextmanager
+import socket
+from typing import Iterable
+
+import grpc
+
+helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
+    "helloworld.proto")
+
+_LOGGER = logging.getLogger(__name__)
+_LOGGER.setLevel(logging.INFO)
+
+
+@contextmanager
+def get_free_loopback_tcp_port() -> Iterable[str]:
+    if socket.has_ipv6:
+        tcp_socket = socket.socket(socket.AF_INET6)
+    else:
+        tcp_socket = socket.socket(socket.AF_INET)
+    tcp_socket.bind(('', 0))
+    address_tuple = tcp_socket.getsockname()
+    yield f"localhost:{address_tuple[1]}"
+    tcp_socket.close()
+
+
+class Greeter(helloworld_pb2_grpc.GreeterServicer):
+
+    async def SayHello(self, request: helloworld_pb2.HelloRequest,
+                       unused_context) -> helloworld_pb2.HelloReply:
+        return helloworld_pb2.HelloReply(message=f'Hello, {request.name}!')
+
+
+def create_server(server_address: str):
+    server = grpc.aio.server()
+    helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
+    bound_port = server.add_insecure_port(server_address)
+    assert bound_port == int(server_address.split(':')[-1])
+    return server
+
+
+async def process(stub: helloworld_pb2_grpc.GreeterStub,
+                  wait_for_ready: bool = None) -> None:
+    try:
+        response = await stub.SayHello(helloworld_pb2.HelloRequest(name='you'),
+                                       wait_for_ready=wait_for_ready)
+        message = response.message
+    except grpc.aio.AioRpcError as rpc_error:
+        assert rpc_error.code() == grpc.StatusCode.UNAVAILABLE
+        assert not wait_for_ready
+        message = rpc_error
+    else:
+        assert wait_for_ready
+    _LOGGER.info("Wait-for-ready %s, client received: %s",
+                 "enabled" if wait_for_ready else "disabled", message)
+
+
+async def main() -> None:
+    # Pick a random free port
+    with get_free_loopback_tcp_port() as server_address:
+        # Create gRPC channel
+        channel = grpc.aio.insecure_channel(server_address)
+        stub = helloworld_pb2_grpc.GreeterStub(channel)
+
+        # Fire an RPC without wait_for_ready
+        fail_fast_task = asyncio.get_event_loop().create_task(
+            process(stub, wait_for_ready=False))
+        # Fire an RPC with wait_for_ready
+        wait_for_ready_task = asyncio.get_event_loop().create_task(
+            process(stub, wait_for_ready=True))
+
+    # Wait for the channel entering TRANSIENT FAILURE state.
+    state = channel.get_state()
+    while state != grpc.ChannelConnectivity.TRANSIENT_FAILURE:
+        await channel.wait_for_state_change(state)
+        state = channel.get_state()
+
+    # Start the server to handle the RPC
+    server = create_server(server_address)
+    await server.start()
+
+    # Expected to fail with StatusCode.UNAVAILABLE.
+    await fail_fast_task
+    # Expected to success.
+    await wait_for_ready_task
+
+    await server.stop(None)
+    await channel.close()
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+    asyncio.get_event_loop().run_until_complete(main())

examples/python/wait_for_ready/helloworld.proto

@@ -0,0 +1 @@
+../../protos/helloworld.proto

examples/python/wait_for_ready/test/_wait_for_ready_example_test.py

@@ -13,10 +13,12 @@
 # limitations under the License.
 """Tests of the wait-for-ready example."""
 
+import asyncio
 import unittest
 import logging
 
 from examples.python.wait_for_ready import wait_for_ready_example
+from examples.python.wait_for_ready import asyncio_wait_for_ready_example
 
 
 class WaitForReadyExampleTest(unittest.TestCase):
@@ -25,7 +27,12 @@ class WaitForReadyExampleTest(unittest.TestCase):
         wait_for_ready_example.main()
         # No unhandled exception raised, no deadlock, test passed!
 
+    def test_asyncio_wait_for_ready_example(self):
+        asyncio.get_event_loop().run_until_complete(
+            asyncio_wait_for_ready_example.main())
+        # No unhandled exception raised, no deadlock, test passed!
+
 
 if __name__ == '__main__':
-    logging.basicConfig()
+    logging.basicConfig(level=logging.DEBUG)
     unittest.main(verbosity=2)

examples/python/wait_for_ready/wait_for_ready_example.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 """The Python example of utilizing wait-for-ready flag."""
 
-from __future__ import print_function
 import logging
 from concurrent import futures
 from contextlib import contextmanager
@@ -22,8 +21,8 @@ import threading
 
 import grpc
 
-from examples import helloworld_pb2
-from examples import helloworld_pb2_grpc
+helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
+    "helloworld.proto")
 
 _LOGGER = logging.getLogger(__name__)
 _LOGGER.setLevel(logging.INFO)

gRPC-C++.podspec

@@ -22,7 +22,7 @@
 Pod::Spec.new do |s|
   s.name     = 'gRPC-C++'
   # TODO (mxyan): use version that match gRPC version when pod is stabilized
-  version = '1.35.0-dev'
+  version = '1.36.0-dev'
   s.version  = version
   s.summary  = 'gRPC C++ library'
   s.homepage = 'https://grpc.io'
@@ -177,7 +177,8 @@ Pod::Spec.new do |s|
                       'include/grpcpp/support/stub_options.h',
                       'include/grpcpp/support/sync_stream.h',
                       'include/grpcpp/support/time.h',
-                      'include/grpcpp/support/validate_service_config.h'
+                      'include/grpcpp/support/validate_service_config.h',
+                      'include/grpcpp/xds_server_builder.h'
   end
 
   s.subspec 'Implementation' do |ss|
@@ -206,6 +207,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/client_channel_factory.h',
                       'src/core/ext/filters/client_channel/config_selector.h',
                       'src/core/ext/filters/client_channel/connector.h',
+                      'src/core/ext/filters/client_channel/dynamic_filters.h',
                       'src/core/ext/filters/client_channel/global_subchannel_pool.h',
                       'src/core/ext/filters/client_channel/health/health_check_client.h',
                       'src/core/ext/filters/client_channel/http_connect_handshaker.h',
@@ -221,6 +223,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
                       'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
                       'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h',
                       'src/core/ext/filters/client_channel/lb_policy_factory.h',
                       'src/core/ext/filters/client_channel/lb_policy_registry.h',
                       'src/core/ext/filters/client_channel/local_subchannel_pool.h',
@@ -505,7 +508,6 @@ Pod::Spec.new do |s|
                       'src/core/lib/gprpp/global_config_generic.h',
                       'src/core/lib/gprpp/host_port.h',
                       'src/core/lib/gprpp/manual_constructor.h',
-                      'src/core/lib/gprpp/map.h',
                       'src/core/lib/gprpp/memory.h',
                       'src/core/lib/gprpp/mpscq.h',
                       'src/core/lib/gprpp/orphanable.h',
@@ -797,10 +799,15 @@ Pod::Spec.new do |s|
                       'third_party/re2/util/test.h',
                       'third_party/re2/util/utf.h',
                       'third_party/re2/util/util.h',
+                      'third_party/upb/third_party/wyhash/wyhash.h',
                       'third_party/upb/upb/decode.h',
+                      'third_party/upb/upb/decode.int.h',
+                      'third_party/upb/upb/decode_fast.h',
                       'third_party/upb/upb/def.h',
                       'third_party/upb/upb/def.hpp',
                       'third_party/upb/upb/encode.h',
+                      'third_party/upb/upb/json_decode.h',
+                      'third_party/upb/upb/json_encode.h',
                       'third_party/upb/upb/msg.h',
                       'third_party/upb/upb/port_def.inc',
                       'third_party/upb/upb/port_undef.inc',
@@ -808,7 +815,8 @@ Pod::Spec.new do |s|
                       'third_party/upb/upb/table.int.h',
                       'third_party/upb/upb/text_encode.h',
                       'third_party/upb/upb/upb.h',
-                      'third_party/upb/upb/upb.hpp'
+                      'third_party/upb/upb/upb.hpp',
+                      'third_party/upb/upb/upb.int.h'
 
     ss.private_header_files = 'src/core/ext/filters/client_channel/backend_metric.h',
                               'src/core/ext/filters/client_channel/backup_poller.h',
@@ -817,6 +825,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/client_channel_factory.h',
                               'src/core/ext/filters/client_channel/config_selector.h',
                               'src/core/ext/filters/client_channel/connector.h',
+                              'src/core/ext/filters/client_channel/dynamic_filters.h',
                               'src/core/ext/filters/client_channel/global_subchannel_pool.h',
                               'src/core/ext/filters/client_channel/health/health_check_client.h',
                               'src/core/ext/filters/client_channel/http_connect_handshaker.h',
@@ -832,6 +841,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
                               'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
                               'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
+                              'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h',
                               'src/core/ext/filters/client_channel/lb_policy_factory.h',
                               'src/core/ext/filters/client_channel/lb_policy_registry.h',
                               'src/core/ext/filters/client_channel/local_subchannel_pool.h',
@@ -1116,7 +1126,6 @@ Pod::Spec.new do |s|
                               'src/core/lib/gprpp/global_config_generic.h',
                               'src/core/lib/gprpp/host_port.h',
                               'src/core/lib/gprpp/manual_constructor.h',
-                              'src/core/lib/gprpp/map.h',
                               'src/core/lib/gprpp/memory.h',
                               'src/core/lib/gprpp/mpscq.h',
                               'src/core/lib/gprpp/orphanable.h',
@@ -1358,10 +1367,15 @@ Pod::Spec.new do |s|
                               'third_party/re2/util/test.h',
                               'third_party/re2/util/utf.h',
                               'third_party/re2/util/util.h',
+                              'third_party/upb/third_party/wyhash/wyhash.h',
                               'third_party/upb/upb/decode.h',
+                              'third_party/upb/upb/decode.int.h',
+                              'third_party/upb/upb/decode_fast.h',
                               'third_party/upb/upb/def.h',
                               'third_party/upb/upb/def.hpp',
                               'third_party/upb/upb/encode.h',
+                              'third_party/upb/upb/json_decode.h',
+                              'third_party/upb/upb/json_encode.h',
                               'third_party/upb/upb/msg.h',
                               'third_party/upb/upb/port_def.inc',
                               'third_party/upb/upb/port_undef.inc',
@@ -1369,7 +1383,8 @@ Pod::Spec.new do |s|
                               'third_party/upb/upb/table.int.h',
                               'third_party/upb/upb/text_encode.h',
                               'third_party/upb/upb/upb.h',
-                              'third_party/upb/upb/upb.hpp'
+                              'third_party/upb/upb/upb.hpp',
+                              'third_party/upb/upb/upb.int.h'
   end
 
   s.subspec 'Protobuf' do |ss|
@@ -1402,6 +1417,7 @@ Pod::Spec.new do |s|
 
   s.prepare_command = <<-END_OF_COMMAND
     sed -E -i '' 's;#include <openssl/(.*)>;#if COCOAPODS==1\\\n  #include <openssl_grpc/\\1>\\\n#else\\\n  #include <openssl/\\1>\\\n#endif;g' $(find src/core -type f \\( -path '*.h' -or -path '*.cc' \\) -print | xargs grep -H -c '#include <openssl_grpc/' | grep 0$ | cut -d':' -f1)
+    find third_party/upb/ -type f \\( -name '*.h' -or -name '*.hpp' -or -name '*.c' -or -name '*.cc' \\) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "third_party/(.*)";#if COCOAPODS==1\\\n  #include  "third_party/upb/third_party/\\1"\\\n#else\\\n  #include  "third_party/\\1"\\\n#endif;g'
     find src/core/ src/cpp/ third_party/upb/ -type f \\( -name '*.h' -or -name '*.hpp' -or -name '*.c' -or -name '*.cc' \\) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "upb/(.*)";#if COCOAPODS==1\\\n  #include  "third_party/upb/upb/\\1"\\\n#else\\\n  #include  "upb/\\1"\\\n#endif;g'
     find src/core/ src/cpp/ third_party/upb/ -type f -name '*.grpc_back' -print0 | xargs -0 rm
     find src/core/ src/cpp/ third_party/upb/ -type f \\( -name '*.h' -or -name '*.c' -or -name '*.cc' \\) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "(.*).upb.h";#if COCOAPODS==1\\\n  #include  "src/core/ext/upb-generated/\\1.upb.h"\\\n#else\\\n  #include  "\\1.upb.h"\\\n#endif;g'

gRPC-Core.podspec

@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-Core'
-  version = '1.35.0-dev'
+  version = '1.36.0-dev'
   s.version  = version
   s.summary  = 'Core cross-platform gRPC library, written in C'
   s.homepage = 'https://grpc.io'
@@ -205,6 +205,8 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/config_selector.cc',
                       'src/core/ext/filters/client_channel/config_selector.h',
                       'src/core/ext/filters/client_channel/connector.h',
+                      'src/core/ext/filters/client_channel/dynamic_filters.cc',
+                      'src/core/ext/filters/client_channel/dynamic_filters.h',
                       'src/core/ext/filters/client_channel/global_subchannel_pool.cc',
                       'src/core/ext/filters/client_channel/global_subchannel_pool.h',
                       'src/core/ext/filters/client_channel/health/health_check_client.cc',
@@ -237,10 +239,11 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
                       'src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc',
                       'src/core/ext/filters/client_channel/lb_policy/xds/cds.cc',
-                      'src/core/ext/filters/client_channel/lb_policy/xds/eds.cc',
                       'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h',
                       'src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc',
                       'src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc',
                       'src/core/ext/filters/client_channel/lb_policy_factory.h',
                       'src/core/ext/filters/client_channel/lb_policy_registry.cc',
                       'src/core/ext/filters/client_channel/lb_policy_registry.h',
@@ -252,14 +255,12 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/resolver.cc',
                       'src/core/ext/filters/client_channel/resolver.h',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
-                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc',
                       '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_ev_driver_libuv.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h',
-                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc',
@@ -722,6 +723,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/xds/xds_client.h',
                       'src/core/ext/xds/xds_client_stats.cc',
                       'src/core/ext/xds/xds_client_stats.h',
+                      'src/core/ext/xds/xds_server_config_fetcher.cc',
                       'src/core/lib/avl/avl.cc',
                       'src/core/lib/avl/avl.h',
                       'src/core/lib/backoff/backoff.cc',
@@ -832,7 +834,6 @@ Pod::Spec.new do |s|
                       'src/core/lib/gprpp/host_port.cc',
                       'src/core/lib/gprpp/host_port.h',
                       'src/core/lib/gprpp/manual_constructor.h',
-                      'src/core/lib/gprpp/map.h',
                       'src/core/lib/gprpp/memory.h',
                       'src/core/lib/gprpp/mpscq.cc',
                       'src/core/lib/gprpp/mpscq.h',
@@ -1319,16 +1320,23 @@ Pod::Spec.new do |s|
                       'third_party/re2/util/test.h',
                       'third_party/re2/util/utf.h',
                       'third_party/re2/util/util.h',
+                      'third_party/upb/third_party/wyhash/wyhash.h',
                       'third_party/upb/upb/decode.c',
                       'third_party/upb/upb/decode.h',
+                      'third_party/upb/upb/decode.int.h',
+                      'third_party/upb/upb/decode_fast.c',
+                      'third_party/upb/upb/decode_fast.h',
                       'third_party/upb/upb/def.c',
                       'third_party/upb/upb/def.h',
                       'third_party/upb/upb/def.hpp',
                       'third_party/upb/upb/encode.c',
                       'third_party/upb/upb/encode.h',
+                      'third_party/upb/upb/json_decode.c',
+                      'third_party/upb/upb/json_decode.h',
+                      'third_party/upb/upb/json_encode.c',
+                      'third_party/upb/upb/json_encode.h',
                       'third_party/upb/upb/msg.c',
                       'third_party/upb/upb/msg.h',
-                      'third_party/upb/upb/port.c',
                       'third_party/upb/upb/port_def.inc',
                       'third_party/upb/upb/port_undef.inc',
                       'third_party/upb/upb/reflection.c',
@@ -1339,7 +1347,8 @@ Pod::Spec.new do |s|
                       'third_party/upb/upb/text_encode.h',
                       'third_party/upb/upb/upb.c',
                       'third_party/upb/upb/upb.h',
-                      'third_party/upb/upb/upb.hpp'
+                      'third_party/upb/upb/upb.hpp',
+                      'third_party/upb/upb/upb.int.h'
     ss.private_header_files = 'src/core/ext/filters/client_channel/backend_metric.h',
                               'src/core/ext/filters/client_channel/backup_poller.h',
                               'src/core/ext/filters/client_channel/client_channel.h',
@@ -1347,6 +1356,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/client_channel_factory.h',
                               'src/core/ext/filters/client_channel/config_selector.h',
                               'src/core/ext/filters/client_channel/connector.h',
+                              'src/core/ext/filters/client_channel/dynamic_filters.h',
                               'src/core/ext/filters/client_channel/global_subchannel_pool.h',
                               'src/core/ext/filters/client_channel/health/health_check_client.h',
                               'src/core/ext/filters/client_channel/http_connect_handshaker.h',
@@ -1362,6 +1372,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
                               'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
                               'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
+                              'src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h',
                               'src/core/ext/filters/client_channel/lb_policy_factory.h',
                               'src/core/ext/filters/client_channel/lb_policy_registry.h',
                               'src/core/ext/filters/client_channel/local_subchannel_pool.h',
@@ -1646,7 +1657,6 @@ Pod::Spec.new do |s|
                               'src/core/lib/gprpp/global_config_generic.h',
                               'src/core/lib/gprpp/host_port.h',
                               'src/core/lib/gprpp/manual_constructor.h',
-                              'src/core/lib/gprpp/map.h',
                               'src/core/lib/gprpp/memory.h',
                               'src/core/lib/gprpp/mpscq.h',
                               'src/core/lib/gprpp/orphanable.h',
@@ -1877,10 +1887,15 @@ Pod::Spec.new do |s|
                               'third_party/re2/util/test.h',
                               'third_party/re2/util/utf.h',
                               'third_party/re2/util/util.h',
+                              'third_party/upb/third_party/wyhash/wyhash.h',
                               'third_party/upb/upb/decode.h',
+                              'third_party/upb/upb/decode.int.h',
+                              'third_party/upb/upb/decode_fast.h',
                               'third_party/upb/upb/def.h',
                               'third_party/upb/upb/def.hpp',
                               'third_party/upb/upb/encode.h',
+                              'third_party/upb/upb/json_decode.h',
+                              'third_party/upb/upb/json_encode.h',
                               'third_party/upb/upb/msg.h',
                               'third_party/upb/upb/port_def.inc',
                               'third_party/upb/upb/port_undef.inc',
@@ -1888,7 +1903,8 @@ Pod::Spec.new do |s|
                               'third_party/upb/upb/table.int.h',
                               'third_party/upb/upb/text_encode.h',
                               'third_party/upb/upb/upb.h',
-                              'third_party/upb/upb/upb.hpp'
+                              'third_party/upb/upb/upb.hpp',
+                              'third_party/upb/upb/upb.int.h'
   end
 
   # CFStream is now default. Leaving this subspec only for compatibility purpose.
@@ -2071,6 +2087,7 @@ Pod::Spec.new do |s|
   # TODO (mxyan): Instead of this hack, add include path "third_party" to C core's include path?
   s.prepare_command = <<-END_OF_COMMAND
     sed -E -i '' 's;#include <openssl/(.*)>;#if COCOAPODS==1\\\n  #include <openssl_grpc/\\1>\\\n#else\\\n  #include <openssl/\\1>\\\n#endif;g' $(find src/core -type f \\( -path '*.h' -or -path '*.cc' \\) -print | xargs grep -H -c '#include <openssl_grpc/' | grep 0$ | cut -d':' -f1)
+    find third_party/upb/ -type f \\( -name '*.h' -or -name '*.hpp' -or -name '*.c' -or -name '*.cc' \\) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "third_party/(.*)";#if COCOAPODS==1\\\n  #include  "third_party/upb/third_party/\\1"\\\n#else\\\n  #include  "third_party/\\1"\\\n#endif;g'
     find src/core/ src/cpp/ third_party/upb/ -type f \\( -name '*.h' -or -name '*.hpp' -or -name '*.c' -or -name '*.cc' \\) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "upb/(.*)";#if COCOAPODS==1\\\n  #include  "third_party/upb/upb/\\1"\\\n#else\\\n  #include  "upb/\\1"\\\n#endif;g'
     find src/core/ src/cpp/ third_party/upb/ -type f -name '*.grpc_back' -print0 | xargs -0 rm
     find src/core/ src/cpp/ third_party/upb/ -type f \\( -name '*.h' -or -name '*.c' -or -name '*.cc' \\) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include "(.*).upb.h";#if COCOAPODS==1\\\n  #include  "src/core/ext/upb-generated/\\1.upb.h"\\\n#else\\\n  #include  "\\1.upb.h"\\\n#endif;g'

gRPC-ProtoRPC.podspec

@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-ProtoRPC'
-  version = '1.35.0-dev'
+  version = '1.36.0-dev'
   s.version  = version
   s.summary  = 'RPC library for Protocol Buffers, based on gRPC'
   s.homepage = 'https://grpc.io'

gRPC-RxLibrary.podspec

@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-RxLibrary'
-  version = '1.35.0-dev'
+  version = '1.36.0-dev'
   s.version  = version
   s.summary  = 'Reactive Extensions library for iOS/OSX.'
   s.homepage = 'https://grpc.io'

gRPC.podspec

@@ -20,7 +20,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC'
-  version = '1.35.0-dev'
+  version = '1.36.0-dev'
   s.version  = version
   s.summary  = 'gRPC client library for iOS/OSX'
   s.homepage = 'https://grpc.io'

grpc.def

@@ -57,6 +57,9 @@ EXPORTS
     grpc_server_request_registered_call
     grpc_server_create
     grpc_server_register_completion_queue
+    grpc_server_config_fetcher_xds_create
+    grpc_server_config_fetcher_destroy
+    grpc_server_set_config_fetcher
     grpc_server_add_insecure_http2_port
     grpc_server_start
     grpc_server_shutdown_and_notify
@@ -107,6 +110,7 @@ EXPORTS
     grpc_google_compute_engine_credentials_create
     grpc_max_auth_token_lifetime
     grpc_service_account_jwt_access_credentials_create
+    grpc_external_account_credentials_create
     grpc_google_refresh_token_credentials_create
     grpc_access_token_credentials_create
     grpc_google_iam_credentials_create

grpc.gemspec

@@ -120,6 +120,8 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/config_selector.cc )
   s.files += %w( src/core/ext/filters/client_channel/config_selector.h )
   s.files += %w( src/core/ext/filters/client_channel/connector.h )
+  s.files += %w( src/core/ext/filters/client_channel/dynamic_filters.cc )
+  s.files += %w( src/core/ext/filters/client_channel/dynamic_filters.h )
   s.files += %w( src/core/ext/filters/client_channel/global_subchannel_pool.cc )
   s.files += %w( src/core/ext/filters/client_channel/global_subchannel_pool.h )
   s.files += %w( src/core/ext/filters/client_channel/health/health_check_client.cc )
@@ -152,10 +154,11 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/subchannel_list.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/cds.cc )
-  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/eds.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds.h )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy_factory.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy_registry.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy_registry.h )
@@ -167,14 +170,12 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/resolver.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver.h )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc )
-  s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc )
   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_ev_driver_libuv.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h )
-  s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc )
@@ -637,6 +638,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/xds/xds_client.h )
   s.files += %w( src/core/ext/xds/xds_client_stats.cc )
   s.files += %w( src/core/ext/xds/xds_client_stats.h )
+  s.files += %w( src/core/ext/xds/xds_server_config_fetcher.cc )
   s.files += %w( src/core/lib/avl/avl.cc )
   s.files += %w( src/core/lib/avl/avl.h )
   s.files += %w( src/core/lib/backoff/backoff.cc )
@@ -747,7 +749,6 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/gprpp/host_port.cc )
   s.files += %w( src/core/lib/gprpp/host_port.h )
   s.files += %w( src/core/lib/gprpp/manual_constructor.h )
-  s.files += %w( src/core/lib/gprpp/map.h )
   s.files += %w( src/core/lib/gprpp/memory.h )
   s.files += %w( src/core/lib/gprpp/mpscq.cc )
   s.files += %w( src/core/lib/gprpp/mpscq.h )
@@ -2023,16 +2024,23 @@ Gem::Specification.new do |s|
   s.files += %w( third_party/re2/util/test.h )
   s.files += %w( third_party/re2/util/utf.h )
   s.files += %w( third_party/re2/util/util.h )
+  s.files += %w( third_party/upb/third_party/wyhash/wyhash.h )
   s.files += %w( third_party/upb/upb/decode.c )
   s.files += %w( third_party/upb/upb/decode.h )
+  s.files += %w( third_party/upb/upb/decode.int.h )
+  s.files += %w( third_party/upb/upb/decode_fast.c )
+  s.files += %w( third_party/upb/upb/decode_fast.h )
   s.files += %w( third_party/upb/upb/def.c )
   s.files += %w( third_party/upb/upb/def.h )
   s.files += %w( third_party/upb/upb/def.hpp )
   s.files += %w( third_party/upb/upb/encode.c )
   s.files += %w( third_party/upb/upb/encode.h )
+  s.files += %w( third_party/upb/upb/json_decode.c )
+  s.files += %w( third_party/upb/upb/json_decode.h )
+  s.files += %w( third_party/upb/upb/json_encode.c )
+  s.files += %w( third_party/upb/upb/json_encode.h )
   s.files += %w( third_party/upb/upb/msg.c )
   s.files += %w( third_party/upb/upb/msg.h )
-  s.files += %w( third_party/upb/upb/port.c )
   s.files += %w( third_party/upb/upb/port_def.inc )
   s.files += %w( third_party/upb/upb/port_undef.inc )
   s.files += %w( third_party/upb/upb/reflection.c )
@@ -2044,6 +2052,7 @@ Gem::Specification.new do |s|
   s.files += %w( third_party/upb/upb/upb.c )
   s.files += %w( third_party/upb/upb/upb.h )
   s.files += %w( third_party/upb/upb/upb.hpp )
+  s.files += %w( third_party/upb/upb/upb.int.h )
   s.files += %w( third_party/zlib/adler32.c )
   s.files += %w( third_party/zlib/compress.c )
   s.files += %w( third_party/zlib/crc32.c )

grpc.gyp

@@ -461,6 +461,7 @@
         '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/config_selector.cc',
+        'src/core/ext/filters/client_channel/dynamic_filters.cc',
         'src/core/ext/filters/client_channel/global_subchannel_pool.cc',
         'src/core/ext/filters/client_channel/health/health_check_client.cc',
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
@@ -479,20 +480,18 @@
         'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
         'src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc',
         'src/core/ext/filters/client_channel/lb_policy/xds/cds.cc',
-        'src/core/ext/filters/client_channel/lb_policy/xds/eds.cc',
         'src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc',
         'src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc',
         'src/core/ext/filters/client_channel/lb_policy_registry.cc',
         'src/core/ext/filters/client_channel/local_subchannel_pool.cc',
         'src/core/ext/filters/client_channel/proxy_mapper_registry.cc',
         'src/core/ext/filters/client_channel/resolver.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
-        'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc',
-        'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc',
@@ -729,6 +728,7 @@
         'src/core/ext/xds/xds_certificate_provider.cc',
         'src/core/ext/xds/xds_client.cc',
         'src/core/ext/xds/xds_client_stats.cc',
+        'src/core/ext/xds/xds_server_config_fetcher.cc',
         'src/core/lib/avl/avl.cc',
         'src/core/lib/backoff/backoff.cc',
         'src/core/lib/channel/channel_args.cc',
@@ -1091,6 +1091,7 @@
         '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/config_selector.cc',
+        'src/core/ext/filters/client_channel/dynamic_filters.cc',
         'src/core/ext/filters/client_channel/global_subchannel_pool.cc',
         'src/core/ext/filters/client_channel/health/health_check_client.cc',
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
@@ -1113,12 +1114,10 @@
         'src/core/ext/filters/client_channel/proxy_mapper_registry.cc',
         'src/core/ext/filters/client_channel/resolver.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
-        'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc',
-        'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc',
@@ -1974,15 +1973,17 @@
       'dependencies': [
       ],
       'sources': [
+        'third_party/upb/upb/decode_fast.c',
         'third_party/upb/upb/decode.c',
+        'third_party/upb/upb/def.c',
         'third_party/upb/upb/encode.c',
+        'third_party/upb/upb/json_decode.c',
+        'third_party/upb/upb/json_encode.c',
         'third_party/upb/upb/msg.c',
-        'third_party/upb/upb/port.c',
-        'third_party/upb/upb/table.c',
-        'third_party/upb/upb/upb.c',
-        'third_party/upb/upb/def.c',
         'third_party/upb/upb/reflection.c',
+        'third_party/upb/upb/table.c',
         'third_party/upb/upb/text_encode.c',
+        'third_party/upb/upb/upb.c',
         'src/core/ext/upb-generated/google/protobuf/any.upb.c',
         'src/core/ext/upb-generated/google/protobuf/descriptor.upb.c',
         'src/core/ext/upb-generated/google/protobuf/duration.upb.c',

include/grpc/grpc.h

@@ -411,6 +411,20 @@ GRPCAPI void grpc_server_register_completion_queue(grpc_server* server,
                                                    grpc_completion_queue* cq,
                                                    void* reserved);
 
+typedef struct grpc_server_config_fetcher grpc_server_config_fetcher;
+
+/** EXPERIMENTAL.  Creates an xDS config fetcher. */
+GRPCAPI grpc_server_config_fetcher* grpc_server_config_fetcher_xds_create();
+
+/** EXPERIMENTAL.  Destroys a config fetcher. */
+GRPCAPI void grpc_server_config_fetcher_destroy(
+    grpc_server_config_fetcher* config_fetcher);
+
+/** EXPERIMENTAL.  Sets the server's config fetcher.  Takes ownership.
+    Must be called before adding ports */
+GRPCAPI void grpc_server_set_config_fetcher(
+    grpc_server* server, grpc_server_config_fetcher* config_fetcher);
+
 /** Add a HTTP2 over plaintext over tcp listener.
     Returns bound port number on success, 0 on failure.
     REQUIRES: server not started */

include/grpc/grpc_security.h

@@ -330,6 +330,14 @@ grpc_service_account_jwt_access_credentials_create(const char* json_key,
                                                    gpr_timespec token_lifetime,
                                                    void* reserved);
 
+/** Builds External Account credentials.
+ - json_string is the JSON string containing the credentials options.
+ - scopes_string contains the scopes to be binded with the credentials.
+   This API is used for experimental purposes for now and may change in the
+ future. */
+GRPCAPI grpc_call_credentials* grpc_external_account_credentials_create(
+    const char* json_string, const char* scopes_string);
+
 /** Creates an Oauth2 Refresh Token credentials object for connecting to Google.
    May return NULL if the input is invalid.
    WARNING: Do NOT use this credentials to connect to a non-google service as
@@ -848,8 +856,8 @@ GRPCAPI grpc_tls_credentials_options* grpc_tls_credentials_options_create(void);
 
 /**
  * Sets the options of whether to request and verify client certs. This should
- * be called only on the server side. It returns 1 on success and 0 on failure.
- * It is used for experimental purpose for now and subject to change.
+ * be called only on the server side. It is used for experimental purpose for
+ * now and subject to change.
  */
 GRPCAPI void grpc_tls_credentials_options_set_cert_request_type(
     grpc_tls_credentials_options* options,
@@ -860,8 +868,7 @@ GRPCAPI void grpc_tls_credentials_options_set_cert_request_type(
  * hostname check, etc. This should be called only on the client side. If
  * |server_verification_option| is not GRPC_TLS_SERVER_VERIFICATION, use of a
  * custom authorization check (grpc_tls_server_authorization_check_config) is
- * mandatory. It returns 1 on success and 0 on failure. It is used for
- * experimental purpose for now and subject to change.
+ * mandatory. It is used for experimental purpose for now and subject to change.
  */
 GRPCAPI void grpc_tls_credentials_options_set_server_verification_option(
     grpc_tls_credentials_options* options,
@@ -870,7 +877,6 @@ GRPCAPI void grpc_tls_credentials_options_set_server_verification_option(
 /**
  * Sets the credential provider in the options.
  * The |options| will implicitly take a new ref to the |provider|.
- * It returns 1 on success and 0 on failure.
  * It is used for experimental purpose for now and subject to change.
  */
 GRPCAPI void grpc_tls_credentials_options_set_certificate_provider(
@@ -879,8 +885,14 @@ GRPCAPI void grpc_tls_credentials_options_set_certificate_provider(
 
 /**
  * If set, gRPC stack will keep watching the root certificates with
- * name |root_cert_name|. It returns 1 on success and 0 on failure. It is used
- * for experimental purpose for now and subject to change.
+ * name |root_cert_name|.
+ * If this is not set on the client side, we will use the root certificates
+ * stored in the default system location, since client side must provide root
+ * certificates in TLS.
+ * If this is not set on the server side, we will not watch any root certificate
+ * updates, and assume no root certificates needed for the server(single-side
+ * TLS). Default root certs on the server side is not supported.
+ * It is used for experimental purpose for now and subject to change.
  */
 GRPCAPI void grpc_tls_credentials_options_watch_root_certs(
     grpc_tls_credentials_options* options);
@@ -895,8 +907,9 @@ GRPCAPI void grpc_tls_credentials_options_set_root_cert_name(
 
 /**
  * If set, gRPC stack will keep watching the identity key-cert pairs
- * with name |identity_cert_name|. It returns 1 on success and 0 on failure. It
- * is used for experimental purpose for now and subject to change.
+ * with name |identity_cert_name|.
+ * This is required on the server side, and optional on the client side.
+ * It is used for experimental purpose for now and subject to change.
  */
 GRPCAPI void grpc_tls_credentials_options_watch_identity_key_cert_pairs(
     grpc_tls_credentials_options* options);
@@ -912,8 +925,8 @@ GRPCAPI void grpc_tls_credentials_options_set_identity_cert_name(
 /**
  * Sets the configuration for a custom authorization check performed at the end
  * of the handshake. The |options| will implicitly take a new ref to the
- * |config|. It returns 1 on success and 0 on failure. It is used for
- * experimental purpose for now and subject to change.
+ * |config|.
+ * It is used for experimental purpose for now and subject to change.
  */
 GRPCAPI void grpc_tls_credentials_options_set_server_authorization_check_config(
     grpc_tls_credentials_options* options,

include/grpcpp/impl/codegen/config_protobuf.h

@@ -65,6 +65,7 @@
 
 #ifndef GRPC_CUSTOM_JSONUTIL
 #include <google/protobuf/util/json_util.h>
+#include <google/protobuf/util/type_resolver_util.h>
 #define GRPC_CUSTOM_JSONUTIL ::google::protobuf::util
 #define GRPC_CUSTOM_UTIL_STATUS ::google::protobuf::util::Status
 #endif

include/grpcpp/security/credentials.h

@@ -307,6 +307,12 @@ grpc::Status StsCredentialsOptionsFromEnv(StsCredentialsOptions* options);
 std::shared_ptr<CallCredentials> StsCredentials(
     const StsCredentialsOptions& options);
 
+/// Builds External Account credentials.
+/// json_string is the JSON string containing the credentials options.
+/// scopes contains the scopes to be binded with the credentials.
+std::shared_ptr<CallCredentials> ExternalAccountCredentials(
+    const grpc::string& json_string, const std::vector<grpc::string>& scopes);
+
 std::shared_ptr<CallCredentials> MetadataCredentialsFromPlugin(
     std::unique_ptr<MetadataCredentialsPlugin> plugin,
     grpc_security_level min_security_level);

include/grpcpp/security/tls_credentials_options.h

@@ -155,13 +155,21 @@ class TlsCredentialsOptions {
   //
   // @param certificate_provider the provider which fetches TLS credentials that
   // will be used in the TLS handshake
-  explicit TlsCredentialsOptions(
-      std::shared_ptr<CertificateProviderInterface> certificate_provider);
+  TlsCredentialsOptions();
   // ---- Setters for member fields ----
+  // Sets the certificate provider used to store root certs and identity certs.
+  void set_certificate_provider(
+      std::shared_ptr<CertificateProviderInterface> certificate_provider);
   // Watches the updates of root certificates with name |root_cert_name|.
-  // If used in TLS credentials, it should always be set unless the root
-  // certificates are not needed(e.g. in the one-side TLS scenario, the server
-  // is not required to verify the client).
+  // If used in TLS credentials, setting this field is optional for both the
+  // client side and the server side.
+  // If this is not set on the client side, we will use the root certificates
+  // stored in the default system location, since client side must provide root
+  // certificates in TLS(no matter single-side TLS or mutual TLS).
+  // If this is not set on the server side, we will not watch any root
+  // certificate updates, and assume no root certificates needed for the server
+  // (in the one-side TLS scenario, the server is not required to provide root
+  // certs). We don't support default root certs on server side.
   void watch_root_certs();
   // Sets the name of root certificates being watched, if |watch_root_certs| is
   // called. If not set, an empty string will be used as the name.
@@ -169,9 +177,9 @@ class TlsCredentialsOptions {
   // @param root_cert_name the name of root certs being set.
   void set_root_cert_name(const std::string& root_cert_name);
   // Watches the updates of identity key-cert pairs with name
-  // |identity_cert_name|. If used in TLS credentials, it should always be set
-  // unless the identity certificates are not needed(e.g. in the one-side TLS
-  // scenario, the client is not required to provide certs).
+  // |identity_cert_name|. If used in TLS credentials, it is required to be set
+  // on the server side, and optional for the client side(in the one-side
+  // TLS scenario, the client is not required to provide identity certs).
   void watch_identity_key_cert_pairs();
   // Sets the name of identity key-cert pairs being watched, if
   // |watch_identity_key_cert_pairs| is called. If not set, an empty string will
@@ -192,13 +200,13 @@ class TlsCredentialsOptions {
 };
 
 // Contains configurable options on the client side.
+// Client side doesn't need to always use certificate provider. When the
+// certificate provider is not set, we will use the root certificates stored
+// in the system default locations, and assume client won't provide any
+// identity certificates(single side TLS).
 // It is used for experimental purposes for now and it is subject to change.
 class TlsChannelCredentialsOptions final : public TlsCredentialsOptions {
  public:
-  explicit TlsChannelCredentialsOptions(
-      std::shared_ptr<CertificateProviderInterface> certificate_provider)
-      : TlsCredentialsOptions(std::move(certificate_provider)) {}
-
   // Sets the option to verify the server.
   // The default is GRPC_TLS_SERVER_VERIFICATION.
   void set_server_verification_option(
@@ -215,9 +223,13 @@ class TlsChannelCredentialsOptions final : public TlsCredentialsOptions {
 // It is used for experimental purposes for now and it is subject to change.
 class TlsServerCredentialsOptions final : public TlsCredentialsOptions {
  public:
+  // Server side is required to use a provider, because server always needs to
+  // use identity certs.
   explicit TlsServerCredentialsOptions(
       std::shared_ptr<CertificateProviderInterface> certificate_provider)
-      : TlsCredentialsOptions(std::move(certificate_provider)) {}
+      : TlsCredentialsOptions() {
+    set_certificate_provider(certificate_provider);
+  }
 
   // Sets option to request the certificates from the client.
   // The default is GRPC_SSL_DONT_REQUEST_CLIENT_CERTIFICATE.

include/grpcpp/server.h

@@ -179,6 +179,7 @@ class Server : public ServerInterface, private GrpcLibraryCodegen {
          int min_pollers, int max_pollers, int sync_cq_timeout_msec,
          std::vector<std::shared_ptr<internal::ExternalConnectionAcceptorImpl>>
              acceptors,
+         grpc_server_config_fetcher* server_config_fetcher = nullptr,
          grpc_resource_quota* server_rq = nullptr,
          std::vector<
              std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>

include/grpcpp/server_builder.h

@@ -347,6 +347,11 @@ class ServerBuilder {
     return option_refs;
   }
 
+  /// Experimental API, subject to change.
+  void set_fetcher(grpc_server_config_fetcher* server_config_fetcher) {
+    server_config_fetcher_ = server_config_fetcher;
+  }
+
  private:
   friend class ::grpc::testing::ServerBuilderPluginTest;
 
@@ -405,6 +410,7 @@ class ServerBuilder {
       interceptor_creators_;
   std::vector<std::shared_ptr<grpc::internal::ExternalConnectionAcceptorImpl>>
       acceptors_;
+  grpc_server_config_fetcher* server_config_fetcher_ = nullptr;
 };
 
 }  // namespace grpc

include/grpcpp/xds_server_builder.h

@@ -0,0 +1,43 @@
+//
+//
+// Copyright 2020 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_XDS_SERVER_BUILDER_H
+#define GRPCPP_XDS_SERVER_BUILDER_H
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include <grpcpp/server_builder.h>
+
+namespace grpc {
+namespace experimental {
+
+class XdsServerBuilder : public ::grpc::ServerBuilder {
+ public:
+  std::unique_ptr<Server> BuildAndStart() override {
+    grpc_server_config_fetcher* fetcher =
+        grpc_server_config_fetcher_xds_create();
+    if (fetcher == nullptr) return nullptr;
+    set_fetcher(fetcher);
+    return ServerBuilder::BuildAndStart();
+  }
+};
+
+}  // namespace experimental
+}  // namespace grpc
+
+#endif /* GRPCPP_XDS_SERVER_BUILDER_H */

package.xml

@@ -13,8 +13,8 @@
  <date>2019-09-24</date>
  <time>16:06:07</time>
  <version>
-  <release>1.35.0dev</release>
-  <api>1.35.0dev</api>
+  <release>1.36.0dev</release>
+  <api>1.36.0dev</api>
  </version>
  <stability>
   <release>beta</release>
@@ -22,7 +22,7 @@
  </stability>
  <license>Apache 2.0</license>
  <notes>
-- gRPC Core 1.35.0 update
+- gRPC Core 1.36.0 update
  </notes>
  <contents>
   <dir baseinstalldir="/" name="/">
@@ -100,6 +100,8 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/config_selector.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/config_selector.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/dynamic_filters.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/dynamic_filters.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/global_subchannel_pool.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/global_subchannel_pool.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/health/health_check_client.cc" role="src" />
@@ -132,10 +134,11 @@
     <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/lb_policy/weighted_target/weighted_target.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/cds.cc" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/eds.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_channel_args.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_impl.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_manager.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_cluster_resolver.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy_factory.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy_registry.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy_registry.h" role="src" />
@@ -147,14 +150,12 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc" 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_ev_driver_libuv.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_libuv.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc" role="src" />
@@ -617,6 +618,7 @@
     <file baseinstalldir="/" name="src/core/ext/xds/xds_client.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/xds/xds_client_stats.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/xds/xds_client_stats.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/xds/xds_server_config_fetcher.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/avl/avl.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/avl/avl.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/backoff/backoff.cc" role="src" />
@@ -727,7 +729,6 @@
     <file baseinstalldir="/" name="src/core/lib/gprpp/host_port.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/gprpp/host_port.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/gprpp/manual_constructor.h" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/gprpp/map.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/gprpp/memory.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/gprpp/mpscq.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/gprpp/mpscq.h" role="src" />
@@ -1948,16 +1949,23 @@
     <file baseinstalldir="/" name="third_party/re2/util/test.h" role="src" />
     <file baseinstalldir="/" name="third_party/re2/util/utf.h" role="src" />
     <file baseinstalldir="/" name="third_party/re2/util/util.h" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/third_party/wyhash/wyhash.h" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/decode.c" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/decode.h" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/decode.int.h" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/decode_fast.c" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/decode_fast.h" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/def.c" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/def.h" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/def.hpp" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/encode.c" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/encode.h" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/json_decode.c" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/json_decode.h" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/json_encode.c" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/json_encode.h" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/msg.c" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/msg.h" role="src" />
-    <file baseinstalldir="/" name="third_party/upb/upb/port.c" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/port_def.inc" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/port_undef.inc" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/reflection.c" role="src" />
@@ -1969,6 +1977,7 @@
     <file baseinstalldir="/" name="third_party/upb/upb/upb.c" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/upb.h" role="src" />
     <file baseinstalldir="/" name="third_party/upb/upb/upb.hpp" role="src" />
+    <file baseinstalldir="/" name="third_party/upb/upb/upb.int.h" role="src" />
     <file baseinstalldir="/" name="third_party/zlib/adler32.c" role="src" />
     <file baseinstalldir="/" name="third_party/zlib/compress.c" role="src" />
     <file baseinstalldir="/" name="third_party/zlib/crc32.c" role="src" />

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

@@ -23,20 +23,18 @@
 #include "udpa/data/orca/v1/orca_load_report.upb.h"
 #include "upb/upb.hpp"
 
-#include "src/core/lib/gprpp/map.h"
-
 namespace grpc_core {
 
 namespace {
 
 template <typename EntryType>
-std::map<absl::string_view, double, StringLess> ParseMap(
+std::map<absl::string_view, double> ParseMap(
     udpa_data_orca_v1_OrcaLoadReport* msg,
     const EntryType* (*entry_func)(const udpa_data_orca_v1_OrcaLoadReport*,
                                    size_t*),
     upb_strview (*key_func)(const EntryType*),
     double (*value_func)(const EntryType*), Arena* arena) {
-  std::map<absl::string_view, double, StringLess> result;
+  std::map<absl::string_view, double> result;
   size_t i = UPB_MAP_BEGIN;
   while (true) {
     const auto* entry = entry_func(msg, &i);

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

@@ -21,6 +21,7 @@
 
 #include <functional>
 #include <map>
+#include <vector>
 
 #include "absl/strings/string_view.h"
 
@@ -28,6 +29,7 @@
 
 #include "src/core/ext/filters/client_channel/service_config.h"
 #include "src/core/ext/filters/client_channel/service_config_parser.h"
+#include "src/core/lib/channel/channel_stack.h"
 #include "src/core/lib/gprpp/arena.h"
 #include "src/core/lib/gprpp/ref_counted.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
@@ -80,6 +82,8 @@ class ConfigSelector : public RefCounted<ConfigSelector> {
     return cs1->Equals(cs2);
   }
 
+  virtual std::vector<const grpc_channel_filter*> GetFilters() { return {}; }
+
   virtual CallConfig GetCallConfig(GetCallConfigArgs args) = 0;
 
   grpc_arg MakeChannelArg() const;

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

@@ -0,0 +1,186 @@
+//
+// Copyright 2020 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/dynamic_filters.h"
+
+#include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/surface/lame_client.h"
+
+// Conversion between call and call stack.
+#define CALL_TO_CALL_STACK(call)                                     \
+  (grpc_call_stack*)((char*)(call) + GPR_ROUND_UP_TO_ALIGNMENT_SIZE( \
+                                         sizeof(DynamicFilters::Call)))
+#define CALL_STACK_TO_CALL(callstack)                     \
+  (DynamicFilters::Call*)(((char*)(call_stack)) -         \
+                          GPR_ROUND_UP_TO_ALIGNMENT_SIZE( \
+                              sizeof(DynamicFilters::Call)))
+
+namespace grpc_core {
+
+//
+// DynamicFilters::Call
+//
+
+DynamicFilters::Call::Call(Args args, grpc_error** error)
+    : channel_stack_(std::move(args.channel_stack)) {
+  grpc_call_stack* call_stack = CALL_TO_CALL_STACK(this);
+  const grpc_call_element_args call_args = {
+      call_stack,        /* call_stack */
+      nullptr,           /* server_transport_data */
+      args.context,      /* context */
+      args.path,         /* path */
+      args.start_time,   /* start_time */
+      args.deadline,     /* deadline */
+      args.arena,        /* arena */
+      args.call_combiner /* call_combiner */
+  };
+  *error = grpc_call_stack_init(channel_stack_->channel_stack_, 1, Destroy,
+                                this, &call_args);
+  if (GPR_UNLIKELY(*error != GRPC_ERROR_NONE)) {
+    const char* error_string = grpc_error_string(*error);
+    gpr_log(GPR_ERROR, "error: %s", error_string);
+    return;
+  }
+  grpc_call_stack_set_pollset_or_pollset_set(call_stack, args.pollent);
+}
+
+void DynamicFilters::Call::StartTransportStreamOpBatch(
+    grpc_transport_stream_op_batch* batch) {
+  grpc_call_stack* call_stack = CALL_TO_CALL_STACK(this);
+  grpc_call_element* top_elem = grpc_call_stack_element(call_stack, 0);
+  GRPC_CALL_LOG_OP(GPR_INFO, top_elem, batch);
+  top_elem->filter->start_transport_stream_op_batch(top_elem, batch);
+}
+
+void DynamicFilters::Call::SetAfterCallStackDestroy(grpc_closure* closure) {
+  GPR_ASSERT(after_call_stack_destroy_ == nullptr);
+  GPR_ASSERT(closure != nullptr);
+  after_call_stack_destroy_ = closure;
+}
+
+RefCountedPtr<DynamicFilters::Call> DynamicFilters::Call::Ref() {
+  IncrementRefCount();
+  return RefCountedPtr<DynamicFilters::Call>(this);
+}
+
+RefCountedPtr<DynamicFilters::Call> DynamicFilters::Call::Ref(
+    const grpc_core::DebugLocation& location, const char* reason) {
+  IncrementRefCount(location, reason);
+  return RefCountedPtr<DynamicFilters::Call>(this);
+}
+
+void DynamicFilters::Call::Unref() {
+  GRPC_CALL_STACK_UNREF(CALL_TO_CALL_STACK(this), "");
+}
+
+void DynamicFilters::Call::Unref(const DebugLocation& /*location*/,
+                                 const char* reason) {
+  GRPC_CALL_STACK_UNREF(CALL_TO_CALL_STACK(this), reason);
+}
+
+void DynamicFilters::Call::Destroy(void* arg, grpc_error* /*error*/) {
+  DynamicFilters::Call* self = static_cast<DynamicFilters::Call*>(arg);
+  // Keep some members before destroying the subchannel call.
+  grpc_closure* after_call_stack_destroy = self->after_call_stack_destroy_;
+  RefCountedPtr<DynamicFilters> channel_stack = std::move(self->channel_stack_);
+  // Destroy the subchannel call.
+  self->~Call();
+  // Destroy the call stack. This should be after destroying the call, because
+  // call->after_call_stack_destroy(), if not null, will free the call arena.
+  grpc_call_stack_destroy(CALL_TO_CALL_STACK(self), nullptr,
+                          after_call_stack_destroy);
+  // Automatically reset channel_stack. This should be after destroying the call
+  // stack, because destroying call stack needs access to the channel stack.
+}
+
+void DynamicFilters::Call::IncrementRefCount() {
+  GRPC_CALL_STACK_REF(CALL_TO_CALL_STACK(this), "");
+}
+
+void DynamicFilters::Call::IncrementRefCount(
+    const grpc_core::DebugLocation& /*location*/, const char* reason) {
+  GRPC_CALL_STACK_REF(CALL_TO_CALL_STACK(this), reason);
+}
+
+//
+// DynamicFilters
+//
+
+namespace {
+
+void DestroyChannelStack(void* arg, grpc_error* /*error*/) {
+  grpc_channel_stack* channel_stack = static_cast<grpc_channel_stack*>(arg);
+  grpc_channel_stack_destroy(channel_stack);
+  gpr_free(channel_stack);
+}
+
+std::pair<grpc_channel_stack*, grpc_error*> CreateChannelStack(
+    const grpc_channel_args* args,
+    std::vector<const grpc_channel_filter*> filters) {
+  // Allocate memory for channel stack.
+  const size_t channel_stack_size =
+      grpc_channel_stack_size(filters.data(), filters.size());
+  grpc_channel_stack* channel_stack =
+      reinterpret_cast<grpc_channel_stack*>(gpr_zalloc(channel_stack_size));
+  // Initialize stack.
+  grpc_error* error = grpc_channel_stack_init(
+      /*initial_refs=*/1, DestroyChannelStack, channel_stack, filters.data(),
+      filters.size(), args, /*optional_transport=*/nullptr, "DynamicFilters",
+      channel_stack);
+  if (error != GRPC_ERROR_NONE) {
+    gpr_log(GPR_ERROR, "error initializing client internal stack: %s",
+            grpc_error_string(error));
+    grpc_channel_stack_destroy(channel_stack);
+    gpr_free(channel_stack);
+    return {nullptr, error};
+  }
+  return {channel_stack, GRPC_ERROR_NONE};
+}
+
+}  // namespace
+
+RefCountedPtr<DynamicFilters> DynamicFilters::Create(
+    const grpc_channel_args* args,
+    std::vector<const grpc_channel_filter*> filters) {
+  // Attempt to create channel stack from requested filters.
+  auto p = CreateChannelStack(args, std::move(filters));
+  if (p.second != GRPC_ERROR_NONE) {
+    // Initial pass failed.  Create with lame filter.
+    grpc_error* error = p.second;
+    p = CreateChannelStack(args, {&grpc_lame_filter});
+    GPR_ASSERT(p.second == GRPC_ERROR_NONE);
+    grpc_channel_element* elem = grpc_channel_stack_element(p.first, 0);
+    SetLameFilterError(elem, error);
+  }
+  return MakeRefCounted<DynamicFilters>(p.first);
+}
+
+DynamicFilters::~DynamicFilters() {
+  GRPC_CHANNEL_STACK_UNREF(channel_stack_, "~DynamicFilters");
+}
+
+RefCountedPtr<DynamicFilters::Call> DynamicFilters::CreateCall(
+    DynamicFilters::Call::Args args, grpc_error** error) {
+  size_t allocation_size = GPR_ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(Call)) +
+                           channel_stack_->call_stack_size;
+  Call* call = static_cast<Call*>(args.arena->Alloc(allocation_size));
+  new (call) Call(std::move(args), error);
+  return call;
+}
+
+}  // namespace grpc_core

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

@@ -0,0 +1,99 @@
+//
+// Copyright 2020 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_DYNAMIC_FILTERS_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_DYNAMIC_FILTERS_H
+
+#include <grpc/support/port_platform.h>
+
+#include <vector>
+
+#include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/gpr/time_precise.h"
+#include "src/core/lib/gprpp/arena.h"
+#include "src/core/lib/gprpp/ref_counted.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
+#include "src/core/lib/iomgr/polling_entity.h"
+
+namespace grpc_core {
+
+class DynamicFilters : public RefCounted<DynamicFilters> {
+ public:
+  // Implements the interface of RefCounted<>.
+  class Call {
+   public:
+    struct Args {
+      RefCountedPtr<DynamicFilters> channel_stack;
+      grpc_polling_entity* pollent;
+      grpc_slice path;
+      gpr_cycle_counter start_time;
+      grpc_millis deadline;
+      Arena* arena;
+      grpc_call_context_element* context;
+      CallCombiner* call_combiner;
+    };
+
+    Call(Args args, grpc_error** error);
+
+    // Continues processing a transport stream op batch.
+    void StartTransportStreamOpBatch(grpc_transport_stream_op_batch* batch);
+
+    // Sets the 'then_schedule_closure' argument for call stack destruction.
+    // Must be called once per call.
+    void SetAfterCallStackDestroy(grpc_closure* closure);
+
+    // Interface of RefCounted<>.
+    RefCountedPtr<Call> Ref() GRPC_MUST_USE_RESULT;
+    RefCountedPtr<Call> Ref(const DebugLocation& location,
+                            const char* reason) GRPC_MUST_USE_RESULT;
+    // When refcount drops to 0, destroys itself and the associated call stack,
+    // but does NOT free the memory because it's in the call arena.
+    void Unref();
+    void Unref(const DebugLocation& location, const char* reason);
+
+   private:
+    // Allow RefCountedPtr<> to access IncrementRefCount().
+    template <typename T>
+    friend class RefCountedPtr;
+
+    // Interface of RefCounted<>.
+    void IncrementRefCount();
+    void IncrementRefCount(const DebugLocation& location, const char* reason);
+
+    static void Destroy(void* arg, grpc_error* error);
+
+    RefCountedPtr<DynamicFilters> channel_stack_;
+    grpc_closure* after_call_stack_destroy_ = nullptr;
+  };
+
+  static RefCountedPtr<DynamicFilters> Create(
+      const grpc_channel_args* args,
+      std::vector<const grpc_channel_filter*> filters);
+
+  explicit DynamicFilters(grpc_channel_stack* channel_stack)
+      : channel_stack_(channel_stack) {}
+
+  ~DynamicFilters() override;
+
+  RefCountedPtr<Call> CreateCall(Call::Args args, grpc_error** error);
+
+ private:
+  grpc_channel_stack* channel_stack_;
+};
+
+}  // namespace grpc_core
+
+#endif  // GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_DYNAMIC_FILTERS_H

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

@@ -46,7 +46,7 @@ TraceFlag grpc_health_check_client_trace(false, "health_check_client");
 //
 
 HealthCheckClient::HealthCheckClient(
-    const char* service_name,
+    std::string service_name,
     RefCountedPtr<ConnectedSubchannel> connected_subchannel,
     grpc_pollset_set* interested_parties,
     RefCountedPtr<channelz::SubchannelNode> channelz_node,
@@ -55,7 +55,7 @@ HealthCheckClient::HealthCheckClient(
           GRPC_TRACE_FLAG_ENABLED(grpc_health_check_client_trace)
               ? "HealthCheckClient"
               : nullptr),
-      service_name_(service_name),
+      service_name_(std::move(service_name)),
       connected_subchannel_(std::move(connected_subchannel)),
       interested_parties_(interested_parties),
       channelz_node_(std::move(channelz_node)),
@@ -180,13 +180,14 @@ void HealthCheckClient::OnRetryTimer(void* arg, grpc_error* error) {
 
 namespace {
 
-void EncodeRequest(const char* service_name,
+void EncodeRequest(const std::string& service_name,
                    ManualConstructor<SliceBufferByteStream>* send_message) {
   upb::Arena arena;
   grpc_health_v1_HealthCheckRequest* request_struct =
       grpc_health_v1_HealthCheckRequest_new(arena.ptr());
   grpc_health_v1_HealthCheckRequest_set_service(
-      request_struct, upb_strview_makez(service_name));
+      request_struct,
+      upb_strview_make(service_name.data(), service_name.size()));
   size_t buf_length;
   char* buf = grpc_health_v1_HealthCheckRequest_serialize(
       request_struct, arena.ptr(), &buf_length);
@@ -252,7 +253,7 @@ HealthCheckClient::CallState::CallState(
     : health_check_client_(std::move(health_check_client)),
       pollent_(grpc_polling_entity_create_from_pollset_set(interested_parties)),
       arena_(Arena::Create(health_check_client_->connected_subchannel_
-                               ->GetInitialCallSizeEstimate(0))),
+                               ->GetInitialCallSizeEstimate())),
       payload_(context_) {}
 
 HealthCheckClient::CallState::~CallState() {
@@ -291,7 +292,6 @@ void HealthCheckClient::CallState::StartCall() {
       arena_,
       context_,
       &call_combiner_,
-      0,  // parent_data_size
   };
   grpc_error* error = GRPC_ERROR_NONE;
   call_ = SubchannelCall::Create(std::move(args), &error).release();

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

@@ -44,7 +44,7 @@ namespace grpc_core {
 
 class HealthCheckClient : public InternallyRefCounted<HealthCheckClient> {
  public:
-  HealthCheckClient(const char* service_name,
+  HealthCheckClient(std::string service_name,
                     RefCountedPtr<ConnectedSubchannel> connected_subchannel,
                     grpc_pollset_set* interested_parties,
                     RefCountedPtr<channelz::SubchannelNode> channelz_node,
@@ -150,7 +150,7 @@ class HealthCheckClient : public InternallyRefCounted<HealthCheckClient> {
   void SetHealthStatusLocked(grpc_connectivity_state state,
                              const char* reason);  // Requires holding mu_.
 
-  const char* service_name_;  // Do not own.
+  std::string service_name_;
   RefCountedPtr<ConnectedSubchannel> connected_subchannel_;
   grpc_pollset_set* interested_parties_;  // Do not own.
   RefCountedPtr<channelz::SubchannelNode> channelz_node_;

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

@@ -30,7 +30,6 @@
 #include "src/core/ext/filters/client_channel/server_address.h"
 #include "src/core/ext/filters/client_channel/service_config.h"
 #include "src/core/ext/filters/client_channel/subchannel_interface.h"
-#include "src/core/lib/gprpp/map.h"
 #include "src/core/lib/gprpp/orphanable.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/polling_entity.h"
@@ -95,11 +94,11 @@ class LoadBalancingPolicy : public InternallyRefCounted<LoadBalancingPolicy> {
     /// Application-specific requests cost metrics.  Metric names are
     /// determined by the application.  Each value is an absolute cost
     /// (e.g. 3487 bytes of storage) associated with the request.
-    std::map<absl::string_view, double, StringLess> request_cost;
+    std::map<absl::string_view, double> request_cost;
     /// Application-specific resource utilization metrics.  Metric names
     /// are determined by the application.  Each value is expressed as a
     /// fraction of total resources available.
-    std::map<absl::string_view, double, StringLess> utilization;
+    std::map<absl::string_view, double> utilization;
   };
 
   /// Interface for accessing per-call state.

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

@@ -330,9 +330,23 @@ void CdsLb::OnClusterChanged(XdsApi::CdsUpdate cluster_data) {
     return OnError(error);
   }
   // Construct config for child policy.
-  Json::Object child_config = {
+  Json::Object discovery_mechanism = {
       {"clusterName", config_->cluster()},
       {"max_concurrent_requests", cluster_data.max_concurrent_requests},
+      {"type", "EDS"},
+  };
+  if (!cluster_data.eds_service_name.empty()) {
+    discovery_mechanism["edsServiceName"] = cluster_data.eds_service_name;
+  }
+  if (cluster_data.lrs_load_reporting_server_name.has_value()) {
+    discovery_mechanism["lrsLoadReportingServerName"] =
+        cluster_data.lrs_load_reporting_server_name.value();
+  }
+  Json::Object child_config = {
+      {"discoveryMechanisms",
+       Json::Array{
+           discovery_mechanism,
+       }},
       {"localityPickingPolicy",
        Json::Array{
            Json::Object{
@@ -349,16 +363,9 @@ void CdsLb::OnClusterChanged(XdsApi::CdsUpdate cluster_data) {
            },
        }},
   };
-  if (!cluster_data.eds_service_name.empty()) {
-    child_config["edsServiceName"] = cluster_data.eds_service_name;
-  }
-  if (cluster_data.lrs_load_reporting_server_name.has_value()) {
-    child_config["lrsLoadReportingServerName"] =
-        cluster_data.lrs_load_reporting_server_name.value();
-  }
   Json json = Json::Array{
       Json::Object{
-          {"eds_experimental", std::move(child_config)},
+          {"xds_cluster_resolver_experimental", std::move(child_config)},
       },
   };
   if (GRPC_TRACE_FLAG_ENABLED(grpc_cds_lb_trace)) {

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

@@ -1,908 +0,0 @@
-//
-// 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 <inttypes.h>
-#include <limits.h>
-
-#include "absl/strings/str_cat.h"
-#include "absl/types/optional.h"
-
-#include <grpc/grpc.h>
-
-#include "src/core/ext/filters/client_channel/client_channel.h"
-#include "src/core/ext/filters/client_channel/lb_policy.h"
-#include "src/core/ext/filters/client_channel/lb_policy/address_filtering.h"
-#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h"
-#include "src/core/ext/filters/client_channel/lb_policy/xds/xds.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/server_address.h"
-#include "src/core/ext/xds/xds_channel_args.h"
-#include "src/core/ext/xds/xds_client.h"
-#include "src/core/ext/xds/xds_client_stats.h"
-#include "src/core/lib/channel/channel_args.h"
-#include "src/core/lib/gpr/string.h"
-#include "src/core/lib/gprpp/orphanable.h"
-#include "src/core/lib/gprpp/ref_counted_ptr.h"
-#include "src/core/lib/iomgr/work_serializer.h"
-#include "src/core/lib/transport/error_utils.h"
-#include "src/core/lib/uri/uri_parser.h"
-
-#define GRPC_EDS_DEFAULT_FALLBACK_TIMEOUT 10000
-
-namespace grpc_core {
-
-TraceFlag grpc_lb_eds_trace(false, "eds_lb");
-
-const char* kXdsLocalityNameAttributeKey = "xds_locality_name";
-
-namespace {
-
-constexpr char kEds[] = "eds_experimental";
-
-// Config for EDS LB policy.
-class EdsLbConfig : public LoadBalancingPolicy::Config {
- public:
-  EdsLbConfig(std::string cluster_name, std::string eds_service_name,
-              absl::optional<std::string> lrs_load_reporting_server_name,
-              Json locality_picking_policy, Json endpoint_picking_policy,
-              uint32_t max_concurrent_requests)
-      : cluster_name_(std::move(cluster_name)),
-        eds_service_name_(std::move(eds_service_name)),
-        lrs_load_reporting_server_name_(
-            std::move(lrs_load_reporting_server_name)),
-        locality_picking_policy_(std::move(locality_picking_policy)),
-        endpoint_picking_policy_(std::move(endpoint_picking_policy)),
-        max_concurrent_requests_(max_concurrent_requests) {}
-
-  const char* name() const override { return kEds; }
-
-  const std::string& cluster_name() const { return cluster_name_; }
-  const std::string& eds_service_name() const { return eds_service_name_; }
-  const absl::optional<std::string>& lrs_load_reporting_server_name() const {
-    return lrs_load_reporting_server_name_;
-  };
-  const Json& locality_picking_policy() const {
-    return locality_picking_policy_;
-  }
-  const Json& endpoint_picking_policy() const {
-    return endpoint_picking_policy_;
-  }
-  const uint32_t max_concurrent_requests() const {
-    return max_concurrent_requests_;
-  }
-
- private:
-  std::string cluster_name_;
-  std::string eds_service_name_;
-  absl::optional<std::string> lrs_load_reporting_server_name_;
-  Json locality_picking_policy_;
-  Json endpoint_picking_policy_;
-  uint32_t max_concurrent_requests_;
-};
-
-// EDS LB policy.
-class EdsLb : public LoadBalancingPolicy {
- public:
-  EdsLb(RefCountedPtr<XdsClient> xds_client, Args args);
-
-  const char* name() const override { return kEds; }
-
-  void UpdateLocked(UpdateArgs args) override;
-  void ResetBackoffLocked() override;
-
- private:
-  class EndpointWatcher : public XdsClient::EndpointWatcherInterface {
-   public:
-    explicit EndpointWatcher(RefCountedPtr<EdsLb> parent)
-        : parent_(std::move(parent)) {}
-    void OnEndpointChanged(XdsApi::EdsUpdate update) override {
-      new Notifier(parent_, std::move(update));
-    }
-    void OnError(grpc_error* error) override { new Notifier(parent_, error); }
-    void OnResourceDoesNotExist() override { new Notifier(parent_); }
-
-   private:
-    class Notifier {
-     public:
-      Notifier(RefCountedPtr<EdsLb> parent, XdsApi::EdsUpdate update);
-      Notifier(RefCountedPtr<EdsLb> parent, grpc_error* error);
-      explicit Notifier(RefCountedPtr<EdsLb> parent);
-
-     private:
-      enum Type { kUpdate, kError, kDoesNotExist };
-
-      static void RunInExecCtx(void* arg, grpc_error* error);
-      void RunInWorkSerializer(grpc_error* error);
-
-      RefCountedPtr<EdsLb> parent_;
-      grpc_closure closure_;
-      XdsApi::EdsUpdate update_;
-      Type type_;
-    };
-
-    RefCountedPtr<EdsLb> parent_;
-  };
-
-  class Helper : public ChannelControlHelper {
-   public:
-    explicit Helper(RefCountedPtr<EdsLb> eds_policy)
-        : eds_policy_(std::move(eds_policy)) {}
-
-    ~Helper() override { eds_policy_.reset(DEBUG_LOCATION, "Helper"); }
-
-    RefCountedPtr<SubchannelInterface> CreateSubchannel(
-        ServerAddress address, const grpc_channel_args& args) override;
-    void UpdateState(grpc_connectivity_state state, const absl::Status& status,
-                     std::unique_ptr<SubchannelPicker> picker) override;
-    // This is a no-op, because we get the addresses from the xds
-    // client, which is a watch-based API.
-    void RequestReresolution() override {}
-    void AddTraceEvent(TraceSeverity severity,
-                       absl::string_view message) override;
-
-   private:
-    RefCountedPtr<EdsLb> eds_policy_;
-  };
-
-  ~EdsLb() override;
-
-  void ShutdownLocked() override;
-
-  void OnEndpointChanged(XdsApi::EdsUpdate update);
-  void OnError(grpc_error* error);
-  void OnResourceDoesNotExist();
-
-  void MaybeDestroyChildPolicyLocked();
-
-  void UpdatePriorityList(XdsApi::EdsUpdate::PriorityList priority_list);
-  void UpdateChildPolicyLocked();
-  OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
-      const grpc_channel_args* args);
-  ServerAddressList CreateChildPolicyAddressesLocked();
-  RefCountedPtr<Config> CreateChildPolicyConfigLocked();
-  grpc_channel_args* CreateChildPolicyArgsLocked(
-      const grpc_channel_args* args_in);
-
-  // Caller must ensure that config_ is set before calling.
-  const absl::string_view GetEdsResourceName() const {
-    if (!is_xds_uri_) return server_name_;
-    if (!config_->eds_service_name().empty()) {
-      return config_->eds_service_name();
-    }
-    return config_->cluster_name();
-  }
-
-  // Returns a pair containing the cluster and eds_service_name to use
-  // for LRS load reporting.
-  // Caller must ensure that config_ is set before calling.
-  std::pair<absl::string_view, absl::string_view> GetLrsClusterKey() const {
-    if (!is_xds_uri_) return {server_name_, nullptr};
-    return {config_->cluster_name(), config_->eds_service_name()};
-  }
-
-  // Server name from target URI.
-  std::string server_name_;
-  bool is_xds_uri_;
-
-  // Current channel args and config from the resolver.
-  const grpc_channel_args* args_ = nullptr;
-  RefCountedPtr<EdsLbConfig> config_;
-
-  // Internal state.
-  bool shutting_down_ = false;
-
-  // The xds client and endpoint watcher.
-  RefCountedPtr<XdsClient> xds_client_;
-  // A pointer to the endpoint watcher, to be used when cancelling the watch.
-  // Note that this is not owned, so this pointer must never be derefernced.
-  EndpointWatcher* endpoint_watcher_ = nullptr;
-  // The latest data from the endpoint watcher.
-  XdsApi::EdsUpdate::PriorityList priority_list_;
-  // State used to retain child policy names for priority policy.
-  std::vector<size_t /*child_number*/> priority_child_numbers_;
-
-  RefCountedPtr<XdsApi::EdsUpdate::DropConfig> drop_config_;
-
-  OrphanablePtr<LoadBalancingPolicy> child_policy_;
-};
-
-//
-// EdsLb::Helper
-//
-
-RefCountedPtr<SubchannelInterface> EdsLb::Helper::CreateSubchannel(
-    ServerAddress address, const grpc_channel_args& args) {
-  if (eds_policy_->shutting_down_) return nullptr;
-  return eds_policy_->channel_control_helper()->CreateSubchannel(
-      std::move(address), args);
-}
-
-void EdsLb::Helper::UpdateState(grpc_connectivity_state state,
-                                const absl::Status& status,
-                                std::unique_ptr<SubchannelPicker> picker) {
-  if (eds_policy_->shutting_down_ || eds_policy_->child_policy_ == nullptr) {
-    return;
-  }
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] child policy updated state=%s (%s) picker=%p",
-            eds_policy_.get(), ConnectivityStateName(state),
-            status.ToString().c_str(), picker.get());
-  }
-  eds_policy_->channel_control_helper()->UpdateState(state, status,
-                                                     std::move(picker));
-}
-
-void EdsLb::Helper::AddTraceEvent(TraceSeverity severity,
-                                  absl::string_view message) {
-  if (eds_policy_->shutting_down_) return;
-  eds_policy_->channel_control_helper()->AddTraceEvent(severity, message);
-}
-
-//
-// EdsLb::EndpointWatcher::Notifier
-//
-
-EdsLb::EndpointWatcher::Notifier::Notifier(RefCountedPtr<EdsLb> parent,
-                                           XdsApi::EdsUpdate update)
-    : parent_(std::move(parent)), update_(std::move(update)), type_(kUpdate) {
-  GRPC_CLOSURE_INIT(&closure_, &RunInExecCtx, this, nullptr);
-  ExecCtx::Run(DEBUG_LOCATION, &closure_, GRPC_ERROR_NONE);
-}
-
-EdsLb::EndpointWatcher::Notifier::Notifier(RefCountedPtr<EdsLb> parent,
-                                           grpc_error* error)
-    : parent_(std::move(parent)), type_(kError) {
-  GRPC_CLOSURE_INIT(&closure_, &RunInExecCtx, this, nullptr);
-  ExecCtx::Run(DEBUG_LOCATION, &closure_, error);
-}
-
-EdsLb::EndpointWatcher::Notifier::Notifier(RefCountedPtr<EdsLb> parent)
-    : parent_(std::move(parent)), type_(kDoesNotExist) {
-  GRPC_CLOSURE_INIT(&closure_, &RunInExecCtx, this, nullptr);
-  ExecCtx::Run(DEBUG_LOCATION, &closure_, GRPC_ERROR_NONE);
-}
-
-void EdsLb::EndpointWatcher::Notifier::RunInExecCtx(void* arg,
-                                                    grpc_error* error) {
-  Notifier* self = static_cast<Notifier*>(arg);
-  GRPC_ERROR_REF(error);
-  self->parent_->work_serializer()->Run(
-      [self, error]() { self->RunInWorkSerializer(error); }, DEBUG_LOCATION);
-}
-
-void EdsLb::EndpointWatcher::Notifier::RunInWorkSerializer(grpc_error* error) {
-  switch (type_) {
-    case kUpdate:
-      parent_->OnEndpointChanged(std::move(update_));
-      break;
-    case kError:
-      parent_->OnError(error);
-      break;
-    case kDoesNotExist:
-      parent_->OnResourceDoesNotExist();
-      break;
-  };
-  delete this;
-}
-
-//
-// EdsLb public methods
-//
-
-EdsLb::EdsLb(RefCountedPtr<XdsClient> xds_client, Args args)
-    : LoadBalancingPolicy(std::move(args)), xds_client_(std::move(xds_client)) {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] created -- using xds client %p", this,
-            xds_client_.get());
-  }
-  // Record server name.
-  const char* server_uri =
-      grpc_channel_args_find_string(args.args, GRPC_ARG_SERVER_URI);
-  GPR_ASSERT(server_uri != nullptr);
-  absl::StatusOr<URI> uri = URI::Parse(server_uri);
-  GPR_ASSERT(uri.ok() && !uri->path().empty());
-  server_name_ = std::string(absl::StripPrefix(uri->path(), "/"));
-  is_xds_uri_ = uri->scheme() == "xds";
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] server name from channel (is_xds_uri=%d): %s",
-            this, is_xds_uri_, server_name_.c_str());
-  }
-  // EDS-only flow.
-  if (!is_xds_uri_) {
-    // Setup channelz linkage.
-    channelz::ChannelNode* parent_channelz_node =
-        grpc_channel_args_find_pointer<channelz::ChannelNode>(
-            args.args, GRPC_ARG_CHANNELZ_CHANNEL_NODE);
-    if (parent_channelz_node != nullptr) {
-      xds_client_->AddChannelzLinkage(parent_channelz_node);
-    }
-    // Couple polling.
-    grpc_pollset_set_add_pollset_set(xds_client_->interested_parties(),
-                                     interested_parties());
-  }
-}
-
-EdsLb::~EdsLb() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] destroying eds LB policy", this);
-  }
-}
-
-void EdsLb::ShutdownLocked() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] shutting down", this);
-  }
-  shutting_down_ = true;
-  MaybeDestroyChildPolicyLocked();
-  // Cancel watcher.
-  if (endpoint_watcher_ != nullptr) {
-    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-      gpr_log(GPR_INFO, "[edslb %p] cancelling xds watch for %s", this,
-              std::string(GetEdsResourceName()).c_str());
-    }
-    xds_client_->CancelEndpointDataWatch(GetEdsResourceName(),
-                                         endpoint_watcher_);
-  }
-  if (!is_xds_uri_) {
-    // Remove channelz linkage.
-    channelz::ChannelNode* parent_channelz_node =
-        grpc_channel_args_find_pointer<channelz::ChannelNode>(
-            args_, GRPC_ARG_CHANNELZ_CHANNEL_NODE);
-    if (parent_channelz_node != nullptr) {
-      xds_client_->RemoveChannelzLinkage(parent_channelz_node);
-    }
-    // Decouple polling.
-    grpc_pollset_set_del_pollset_set(xds_client_->interested_parties(),
-                                     interested_parties());
-  }
-  xds_client_.reset(DEBUG_LOCATION, "EdsLb");
-  // Destroy channel args.
-  grpc_channel_args_destroy(args_);
-  args_ = nullptr;
-}
-
-void EdsLb::MaybeDestroyChildPolicyLocked() {
-  if (child_policy_ != nullptr) {
-    grpc_pollset_set_del_pollset_set(child_policy_->interested_parties(),
-                                     interested_parties());
-    child_policy_.reset();
-  }
-}
-
-void EdsLb::UpdateLocked(UpdateArgs args) {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] Received update", this);
-  }
-  const bool is_initial_update = args_ == nullptr;
-  // Update config.
-  auto old_config = std::move(config_);
-  config_ = std::move(args.config);
-  // Update args.
-  grpc_channel_args_destroy(args_);
-  args_ = args.args;
-  args.args = nullptr;
-  // Update child policy if needed.
-  if (child_policy_ != nullptr) UpdateChildPolicyLocked();
-  // Create endpoint watcher if needed.
-  if (is_initial_update) {
-    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-      gpr_log(GPR_INFO, "[edslb %p] starting xds watch for %s", this,
-              std::string(GetEdsResourceName()).c_str());
-    }
-    auto watcher = absl::make_unique<EndpointWatcher>(
-        Ref(DEBUG_LOCATION, "EndpointWatcher"));
-    endpoint_watcher_ = watcher.get();
-    xds_client_->WatchEndpointData(GetEdsResourceName(), std::move(watcher));
-  }
-}
-
-void EdsLb::ResetBackoffLocked() {
-  // When the XdsClient is instantiated in the resolver instead of in this
-  // LB policy, this is done via the resolver, so we don't need to do it here.
-  if (!is_xds_uri_ && xds_client_ != nullptr) xds_client_->ResetBackoff();
-  if (child_policy_ != nullptr) {
-    child_policy_->ResetBackoffLocked();
-  }
-}
-
-void EdsLb::OnEndpointChanged(XdsApi::EdsUpdate update) {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] Received EDS update from xds client", this);
-  }
-  // Update the drop config.
-  drop_config_ = std::move(update.drop_config);
-  // If priority list is empty, add a single priority, just so that we
-  // have a child in which to create the xds_cluster_impl policy.
-  if (update.priorities.empty()) update.priorities.emplace_back();
-  // Update child policy.
-  UpdatePriorityList(std::move(update.priorities));
-}
-
-void EdsLb::OnError(grpc_error* error) {
-  gpr_log(GPR_ERROR, "[edslb %p] xds watcher reported error: %s", this,
-          grpc_error_string(error));
-  // Go into TRANSIENT_FAILURE if we have not yet created the child
-  // policy (i.e., we have not yet received data from xds).  Otherwise,
-  // we keep running with the data we had previously.
-  if (child_policy_ == nullptr) {
-    channel_control_helper()->UpdateState(
-        GRPC_CHANNEL_TRANSIENT_FAILURE, grpc_error_to_absl_status(error),
-        absl::make_unique<TransientFailurePicker>(error));
-  } else {
-    GRPC_ERROR_UNREF(error);
-  }
-}
-
-void EdsLb::OnResourceDoesNotExist() {
-  gpr_log(
-      GPR_ERROR,
-      "[edslb %p] EDS resource does not exist -- reporting TRANSIENT_FAILURE",
-      this);
-  grpc_error* error = grpc_error_set_int(
-      GRPC_ERROR_CREATE_FROM_STATIC_STRING("EDS resource does not exist"),
-      GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE);
-  channel_control_helper()->UpdateState(
-      GRPC_CHANNEL_TRANSIENT_FAILURE, grpc_error_to_absl_status(error),
-      absl::make_unique<TransientFailurePicker>(error));
-  MaybeDestroyChildPolicyLocked();
-}
-
-//
-// child policy-related methods
-//
-
-void EdsLb::UpdatePriorityList(XdsApi::EdsUpdate::PriorityList priority_list) {
-  // Build some maps from locality to child number and the reverse from
-  // the old data in priority_list_ and priority_child_numbers_.
-  std::map<XdsLocalityName*, size_t /*child_number*/, XdsLocalityName::Less>
-      locality_child_map;
-  std::map<size_t, std::set<XdsLocalityName*>> child_locality_map;
-  for (size_t priority = 0; priority < priority_list_.size(); ++priority) {
-    size_t child_number = priority_child_numbers_[priority];
-    const auto& localities = priority_list_[priority].localities;
-    for (const auto& p : localities) {
-      XdsLocalityName* locality_name = p.first;
-      locality_child_map[locality_name] = child_number;
-      child_locality_map[child_number].insert(locality_name);
-    }
-  }
-  // Construct new list of children.
-  std::vector<size_t> priority_child_numbers;
-  for (size_t priority = 0; priority < priority_list.size(); ++priority) {
-    const auto& localities = priority_list[priority].localities;
-    absl::optional<size_t> child_number;
-    // If one of the localities in this priority already existed, reuse its
-    // child number.
-    for (const auto& p : localities) {
-      XdsLocalityName* locality_name = p.first;
-      if (!child_number.has_value()) {
-        auto it = locality_child_map.find(locality_name);
-        if (it != locality_child_map.end()) {
-          child_number = it->second;
-          locality_child_map.erase(it);
-          // Remove localities that *used* to be in this child number, so
-          // that we don't incorrectly reuse this child number for a
-          // subsequent priority.
-          for (XdsLocalityName* old_locality :
-               child_locality_map[*child_number]) {
-            locality_child_map.erase(old_locality);
-          }
-        }
-      } else {
-        // Remove all localities that are now in this child number, so
-        // that we don't accidentally reuse this child number for a
-        // subsequent priority.
-        locality_child_map.erase(locality_name);
-      }
-    }
-    // If we didn't find an existing child number, assign a new one.
-    if (!child_number.has_value()) {
-      for (child_number = 0;
-           child_locality_map.find(*child_number) != child_locality_map.end();
-           ++(*child_number)) {
-      }
-      // Add entry so we know that the child number is in use.
-      // (Don't need to add the list of localities, since we won't use them.)
-      child_locality_map[*child_number];
-    }
-    priority_child_numbers.push_back(*child_number);
-  }
-  // Save update.
-  priority_list_ = std::move(priority_list);
-  priority_child_numbers_ = std::move(priority_child_numbers);
-  // Update child policy.
-  UpdateChildPolicyLocked();
-}
-
-ServerAddressList EdsLb::CreateChildPolicyAddressesLocked() {
-  ServerAddressList addresses;
-  for (size_t priority = 0; priority < priority_list_.size(); ++priority) {
-    const auto& localities = priority_list_[priority].localities;
-    std::string priority_child_name =
-        absl::StrCat("child", priority_child_numbers_[priority]);
-    for (const auto& p : localities) {
-      const auto& locality_name = p.first;
-      const auto& locality = p.second;
-      std::vector<std::string> hierarchical_path = {
-          priority_child_name, locality_name->AsHumanReadableString()};
-      for (const auto& endpoint : locality.endpoints) {
-        addresses.emplace_back(
-            endpoint
-                .WithAttribute(kHierarchicalPathAttributeKey,
-                               MakeHierarchicalPathAttribute(hierarchical_path))
-                .WithAttribute(kXdsLocalityNameAttributeKey,
-                               absl::make_unique<XdsLocalityAttribute>(
-                                   locality_name->Ref())));
-      }
-    }
-  }
-  return addresses;
-}
-
-RefCountedPtr<LoadBalancingPolicy::Config>
-EdsLb::CreateChildPolicyConfigLocked() {
-  const auto lrs_key = GetLrsClusterKey();
-  Json::Object priority_children;
-  Json::Array priority_priorities;
-  for (size_t priority = 0; priority < priority_list_.size(); ++priority) {
-    const auto& localities = priority_list_[priority].localities;
-    Json::Object weighted_targets;
-    for (const auto& p : localities) {
-      XdsLocalityName* locality_name = p.first;
-      const auto& locality = p.second;
-      // Construct JSON object containing locality name.
-      Json::Object locality_name_json;
-      if (!locality_name->region().empty()) {
-        locality_name_json["region"] = locality_name->region();
-      }
-      if (!locality_name->zone().empty()) {
-        locality_name_json["zone"] = locality_name->zone();
-      }
-      if (!locality_name->sub_zone().empty()) {
-        locality_name_json["subzone"] = locality_name->sub_zone();
-      }
-      // Add weighted target entry.
-      weighted_targets[locality_name->AsHumanReadableString()] = Json::Object{
-          {"weight", locality.lb_weight},
-          {"childPolicy", config_->endpoint_picking_policy()},
-      };
-    }
-    // Construct locality-picking policy.
-    // Start with field from our config and add the "targets" field.
-    Json locality_picking_config = config_->locality_picking_policy();
-    Json::Object& config =
-        *(*locality_picking_config.mutable_array())[0].mutable_object();
-    auto it = config.begin();
-    GPR_ASSERT(it != config.end());
-    (*it->second.mutable_object())["targets"] = std::move(weighted_targets);
-    // Wrap it in the drop policy.
-    Json::Array drop_categories;
-    for (const auto& category : drop_config_->drop_category_list()) {
-      drop_categories.push_back(Json::Object{
-          {"category", category.name},
-          {"requests_per_million", category.parts_per_million},
-      });
-    }
-    Json::Object xds_cluster_impl_config = {
-        {"clusterName", std::string(lrs_key.first)},
-        {"childPolicy", std::move(locality_picking_config)},
-        {"dropCategories", std::move(drop_categories)},
-        {"maxConcurrentRequests", config_->max_concurrent_requests()},
-    };
-    if (!lrs_key.second.empty()) {
-      xds_cluster_impl_config["edsServiceName"] = std::string(lrs_key.second);
-    }
-    if (config_->lrs_load_reporting_server_name().has_value()) {
-      xds_cluster_impl_config["lrsLoadReportingServerName"] =
-          config_->lrs_load_reporting_server_name().value();
-    }
-    Json locality_picking_policy = Json::Array{Json::Object{
-        {"xds_cluster_impl_experimental", std::move(xds_cluster_impl_config)},
-    }};
-    // Add priority entry.
-    const size_t child_number = priority_child_numbers_[priority];
-    std::string child_name = absl::StrCat("child", child_number);
-    priority_priorities.emplace_back(child_name);
-    priority_children[child_name] = Json::Object{
-        {"config", std::move(locality_picking_policy)},
-        {"ignore_reresolution_requests", true},
-    };
-  }
-  Json json = Json::Array{Json::Object{
-      {"priority_experimental",
-       Json::Object{
-           {"children", std::move(priority_children)},
-           {"priorities", std::move(priority_priorities)},
-       }},
-  }};
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    std::string json_str = json.Dump(/*indent=*/1);
-    gpr_log(GPR_INFO, "[edslb %p] generated config for child policy: %s", this,
-            json_str.c_str());
-  }
-  grpc_error* error = GRPC_ERROR_NONE;
-  RefCountedPtr<LoadBalancingPolicy::Config> config =
-      LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(json, &error);
-  if (error != GRPC_ERROR_NONE) {
-    // This should never happen, but if it does, we basically have no
-    // way to fix it, so we put the channel in TRANSIENT_FAILURE.
-    gpr_log(GPR_ERROR,
-            "[edslb %p] error parsing generated child policy config -- "
-            "will put channel in TRANSIENT_FAILURE: %s",
-            this, grpc_error_string(error));
-    error = grpc_error_set_int(
-        grpc_error_add_child(
-            GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-                "eds LB policy: error parsing generated child policy config"),
-            error),
-        GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_INTERNAL);
-    channel_control_helper()->UpdateState(
-        GRPC_CHANNEL_TRANSIENT_FAILURE, grpc_error_to_absl_status(error),
-        absl::make_unique<TransientFailurePicker>(error));
-    return nullptr;
-  }
-  return config;
-}
-
-void EdsLb::UpdateChildPolicyLocked() {
-  if (shutting_down_) return;
-  UpdateArgs update_args;
-  update_args.config = CreateChildPolicyConfigLocked();
-  if (update_args.config == nullptr) return;
-  update_args.addresses = CreateChildPolicyAddressesLocked();
-  update_args.args = CreateChildPolicyArgsLocked(args_);
-  if (child_policy_ == nullptr) {
-    child_policy_ = CreateChildPolicyLocked(update_args.args);
-  }
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p] Updating child policy %p", this,
-            child_policy_.get());
-  }
-  child_policy_->UpdateLocked(std::move(update_args));
-}
-
-grpc_channel_args* EdsLb::CreateChildPolicyArgsLocked(
-    const grpc_channel_args* args) {
-  grpc_arg args_to_add[] = {
-      // A channel arg indicating if the target is a backend inferred from an
-      // xds load balancer.
-      // TODO(roth): This isn't needed with the new fallback design.
-      // Remove as part of implementing the new fallback functionality.
-      grpc_channel_arg_integer_create(
-          const_cast<char*>(GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER),
-          1),
-      // Inhibit client-side health checking, since the balancer does
-      // this for us.
-      grpc_channel_arg_integer_create(
-          const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1),
-  };
-  return grpc_channel_args_copy_and_add(args, args_to_add,
-                                        GPR_ARRAY_SIZE(args_to_add));
-}
-
-OrphanablePtr<LoadBalancingPolicy> EdsLb::CreateChildPolicyLocked(
-    const grpc_channel_args* args) {
-  LoadBalancingPolicy::Args lb_policy_args;
-  lb_policy_args.work_serializer = work_serializer();
-  lb_policy_args.args = args;
-  lb_policy_args.channel_control_helper =
-      absl::make_unique<Helper>(Ref(DEBUG_LOCATION, "Helper"));
-  OrphanablePtr<LoadBalancingPolicy> lb_policy =
-      LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
-          "priority_experimental", std::move(lb_policy_args));
-  if (GPR_UNLIKELY(lb_policy == nullptr)) {
-    gpr_log(GPR_ERROR, "[edslb %p] failure creating child policy", this);
-    return nullptr;
-  }
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
-    gpr_log(GPR_INFO, "[edslb %p]: Created new child policy %p", this,
-            lb_policy.get());
-  }
-  // Add our interested_parties pollset_set to that of the newly created
-  // child policy. This will make the child policy progress upon activity on
-  // this policy, which in turn is tied to the application's call.
-  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
-                                   interested_parties());
-  return lb_policy;
-}
-
-//
-// factory
-//
-
-class EdsLbFactory : public LoadBalancingPolicyFactory {
- public:
-  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
-      LoadBalancingPolicy::Args args) const override {
-    grpc_error* error = GRPC_ERROR_NONE;
-    RefCountedPtr<XdsClient> xds_client = XdsClient::GetOrCreate(&error);
-    if (error != GRPC_ERROR_NONE) {
-      gpr_log(GPR_ERROR,
-              "cannot get XdsClient to instantiate eds LB policy: %s",
-              grpc_error_string(error));
-      GRPC_ERROR_UNREF(error);
-      return nullptr;
-    }
-    return MakeOrphanable<EdsChildHandler>(std::move(xds_client),
-                                           std::move(args));
-  }
-
-  const char* name() const override { return kEds; }
-
-  RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
-      const Json& json, grpc_error** error) const override {
-    GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
-    if (json.type() == Json::Type::JSON_NULL) {
-      // eds was mentioned as a policy in the deprecated loadBalancingPolicy
-      // field or in the client API.
-      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-          "field:loadBalancingPolicy error:eds policy requires configuration. "
-          "Please use loadBalancingConfig field of service config instead.");
-      return nullptr;
-    }
-    std::vector<grpc_error*> error_list;
-    // EDS service name.
-    std::string eds_service_name;
-    auto it = json.object_value().find("edsServiceName");
-    if (it != json.object_value().end()) {
-      if (it->second.type() != Json::Type::STRING) {
-        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-            "field:edsServiceName error:type should be string"));
-      } else {
-        eds_service_name = it->second.string_value();
-      }
-    }
-    // Cluster name.
-    std::string cluster_name;
-    it = json.object_value().find("clusterName");
-    if (it == json.object_value().end()) {
-      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-          "field:clusterName error:required field missing"));
-    } else if (it->second.type() != Json::Type::STRING) {
-      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-          "field:clusterName error:type should be string"));
-    } else {
-      cluster_name = it->second.string_value();
-    }
-    // LRS load reporting server name.
-    absl::optional<std::string> lrs_load_reporting_server_name;
-    it = json.object_value().find("lrsLoadReportingServerName");
-    if (it != json.object_value().end()) {
-      if (it->second.type() != Json::Type::STRING) {
-        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-            "field:lrsLoadReportingServerName error:type should be string"));
-      } else {
-        lrs_load_reporting_server_name.emplace(it->second.string_value());
-      }
-    }
-    // Locality-picking policy.
-    Json locality_picking_policy;
-    it = json.object_value().find("localityPickingPolicy");
-    if (it == json.object_value().end()) {
-      locality_picking_policy = Json::Array{
-          Json::Object{
-              {"weighted_target_experimental",
-               Json::Object{
-                   {"targets", Json::Object()},
-               }},
-          },
-      };
-    } else {
-      locality_picking_policy = it->second;
-    }
-    grpc_error* parse_error = GRPC_ERROR_NONE;
-    if (LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
-            locality_picking_policy, &parse_error) == nullptr) {
-      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
-      error_list.push_back(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
-          "localityPickingPolicy", &parse_error, 1));
-      GRPC_ERROR_UNREF(parse_error);
-    }
-    // Endpoint-picking policy.  Called "childPolicy" for xds policy.
-    Json endpoint_picking_policy;
-    it = json.object_value().find("endpointPickingPolicy");
-    if (it == json.object_value().end()) {
-      endpoint_picking_policy = Json::Array{
-          Json::Object{
-              {"round_robin", Json::Object()},
-          },
-      };
-    } else {
-      endpoint_picking_policy = it->second;
-    }
-    parse_error = GRPC_ERROR_NONE;
-    if (LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
-            endpoint_picking_policy, &parse_error) == nullptr) {
-      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
-      error_list.push_back(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
-          "endpointPickingPolicy", &parse_error, 1));
-      GRPC_ERROR_UNREF(parse_error);
-    }
-    // Max concurrent requests.
-    uint32_t max_concurrent_requests = 1024;
-    it = json.object_value().find("max_concurrent_requests");
-    if (it != json.object_value().end()) {
-      if (it->second.type() != Json::Type::NUMBER) {
-        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-            "field:max_concurrent_requests error:must be of type number"));
-      } else {
-        max_concurrent_requests =
-            gpr_parse_nonnegative_int(it->second.string_value().c_str());
-      }
-    }
-    // Construct config.
-    if (error_list.empty()) {
-      return MakeRefCounted<EdsLbConfig>(
-          std::move(cluster_name), std::move(eds_service_name),
-          std::move(lrs_load_reporting_server_name),
-          std::move(locality_picking_policy),
-          std::move(endpoint_picking_policy), max_concurrent_requests);
-    } else {
-      *error = GRPC_ERROR_CREATE_FROM_VECTOR(
-          "eds_experimental LB policy config", &error_list);
-      return nullptr;
-    }
-  }
-
- private:
-  class EdsChildHandler : public ChildPolicyHandler {
-   public:
-    EdsChildHandler(RefCountedPtr<XdsClient> xds_client, Args args)
-        : ChildPolicyHandler(std::move(args), &grpc_lb_eds_trace),
-          xds_client_(std::move(xds_client)) {}
-
-    bool ConfigChangeRequiresNewPolicyInstance(
-        LoadBalancingPolicy::Config* old_config,
-        LoadBalancingPolicy::Config* new_config) const override {
-      GPR_ASSERT(old_config->name() == kEds);
-      GPR_ASSERT(new_config->name() == kEds);
-      EdsLbConfig* old_eds_config = static_cast<EdsLbConfig*>(old_config);
-      EdsLbConfig* new_eds_config = static_cast<EdsLbConfig*>(new_config);
-      return old_eds_config->cluster_name() != new_eds_config->cluster_name() ||
-             old_eds_config->eds_service_name() !=
-                 new_eds_config->eds_service_name() ||
-             old_eds_config->lrs_load_reporting_server_name() !=
-                 new_eds_config->lrs_load_reporting_server_name();
-    }
-
-    OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
-        const char* name, LoadBalancingPolicy::Args args) const override {
-      return MakeOrphanable<EdsLb>(xds_client_, std::move(args));
-    }
-
-   private:
-    RefCountedPtr<XdsClient> xds_client_;
-  };
-};
-
-}  // namespace
-
-}  // namespace grpc_core
-
-//
-// Plugin registration
-//
-
-void grpc_lb_policy_eds_init() {
-  grpc_core::LoadBalancingPolicyRegistry::Builder::
-      RegisterLoadBalancingPolicyFactory(
-          absl::make_unique<grpc_core::EdsLbFactory>());
-}
-
-void grpc_lb_policy_eds_shutdown() {}

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

@@ -23,14 +23,6 @@
 #include "src/core/ext/xds/xds_client_stats.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 
-/** 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. */
-// TODO(roth): Depending on how we ultimately decide to handle fallback,
-// this may no longer be needed.
-#define GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER \
-  "grpc.address_is_backend_from_xds_load_balancer"
-
 namespace grpc_core {
 
 // Defined in the EDS policy.

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

@@ -0,0 +1,24 @@
+//
+// Copyright 2020 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_ARGS_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CHANNEL_ARGS_H
+
+// Channel arg indicating the xDS cluster name.
+// Set by xds_cluster_impl LB policy and used by GoogleDefaultCredentials.
+#define GRPC_ARG_XDS_CLUSTER_NAME "grpc.internal.xds_cluster_name"
+
+#endif  // GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_CHANNEL_ARGS_H

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

@@ -23,6 +23,7 @@
 #include "src/core/ext/filters/client_channel/lb_policy.h"
 #include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.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_args.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/xds/xds_client.h"
@@ -454,7 +455,6 @@ void XdsClusterImplLb::UpdateLocked(UpdateArgs args) {
   }
   // Update child policy.
   UpdateChildPolicyLocked(std::move(args.addresses), args.args);
-  args.args = nullptr;
 }
 
 void XdsClusterImplLb::MaybeUpdatePickerLocked() {
@@ -522,7 +522,10 @@ void XdsClusterImplLb::UpdateChildPolicyLocked(ServerAddressList addresses,
   UpdateArgs update_args;
   update_args.addresses = std::move(addresses);
   update_args.config = config_->child_policy();
-  update_args.args = args;
+  grpc_arg cluster_arg = grpc_channel_arg_string_create(
+      const_cast<char*>(GRPC_ARG_XDS_CLUSTER_NAME),
+      const_cast<char*>(config_->cluster_name().c_str()));
+  update_args.args = grpc_channel_args_copy_and_add(args, &cluster_arg, 1);
   // Update the policy.
   if (GRPC_TRACE_FLAG_ENABLED(grpc_xds_cluster_impl_lb_trace)) {
     gpr_log(GPR_INFO,

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

@@ -0,0 +1,1262 @@
+//
+// 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 <inttypes.h>
+#include <limits.h>
+
+#include "absl/strings/str_cat.h"
+#include "absl/types/optional.h"
+
+#include <grpc/grpc.h>
+
+#include "src/core/ext/filters/client_channel/client_channel.h"
+#include "src/core/ext/filters/client_channel/lb_policy.h"
+#include "src/core/ext/filters/client_channel/lb_policy/address_filtering.h"
+#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds.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/resolver_registry.h"
+#include "src/core/ext/filters/client_channel/server_address.h"
+#include "src/core/ext/xds/xds_channel_args.h"
+#include "src/core/ext/xds/xds_client.h"
+#include "src/core/ext/xds/xds_client_stats.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/work_serializer.h"
+#include "src/core/lib/transport/error_utils.h"
+#include "src/core/lib/uri/uri_parser.h"
+
+#define GRPC_EDS_DEFAULT_FALLBACK_TIMEOUT 10000
+
+namespace grpc_core {
+
+TraceFlag grpc_lb_xds_cluster_resolver_trace(false, "xds_cluster_resolver_lb");
+
+const char* kXdsLocalityNameAttributeKey = "xds_locality_name";
+
+namespace {
+
+constexpr char kXdsClusterResolver[] = "xds_cluster_resolver_experimental";
+
+// Config for EDS LB policy.
+class XdsClusterResolverLbConfig : public LoadBalancingPolicy::Config {
+ public:
+  struct DiscoveryMechanism {
+    std::string cluster_name;
+    absl::optional<std::string> lrs_load_reporting_server_name;
+    uint32_t max_concurrent_requests;
+    enum DiscoveryMechanismType {
+      EDS,
+      LOGICAL_DNS,
+    };
+    DiscoveryMechanismType type;
+    std::string eds_service_name;
+
+    bool operator==(const DiscoveryMechanism& other) const {
+      return (cluster_name == other.cluster_name &&
+              lrs_load_reporting_server_name ==
+                  other.lrs_load_reporting_server_name &&
+              max_concurrent_requests == other.max_concurrent_requests &&
+              type == other.type && eds_service_name == other.eds_service_name);
+    }
+  };
+
+  XdsClusterResolverLbConfig(
+      std::vector<DiscoveryMechanism> discovery_mechanisms,
+      Json locality_picking_policy, Json endpoint_picking_policy)
+      : discovery_mechanisms_(std::move(discovery_mechanisms)),
+        locality_picking_policy_(std::move(locality_picking_policy)),
+        endpoint_picking_policy_(std::move(endpoint_picking_policy)) {}
+
+  const char* name() const override { return kXdsClusterResolver; }
+
+  const std::vector<DiscoveryMechanism>& discovery_mechanisms() const {
+    return discovery_mechanisms_;
+  }
+  const Json& locality_picking_policy() const {
+    return locality_picking_policy_;
+  }
+  const Json& endpoint_picking_policy() const {
+    return endpoint_picking_policy_;
+  }
+
+ private:
+  std::vector<DiscoveryMechanism> discovery_mechanisms_;
+  Json locality_picking_policy_;
+  Json endpoint_picking_policy_;
+};
+
+// Xds Cluster Resolver LB policy.
+class XdsClusterResolverLb : public LoadBalancingPolicy {
+ public:
+  XdsClusterResolverLb(RefCountedPtr<XdsClient> xds_client, Args args);
+
+  const char* name() const override { return kXdsClusterResolver; }
+
+  void UpdateLocked(UpdateArgs args) override;
+  void ResetBackoffLocked() override;
+
+ private:
+  // Discovery Mechanism Base class
+  //
+  // Implemented by EDS and LOGICAL_DNS.
+  //
+  // Implementations are responsible for calling the LB policy's
+  // OnEndpointChanged(), OnError(), and OnResourceDoesNotExist()
+  // methods when the corresponding events occur.
+  //
+  // Must implement Orphan() method to cancel the watchers.
+  class DiscoveryMechanism : public InternallyRefCounted<DiscoveryMechanism> {
+   public:
+    DiscoveryMechanism(
+        RefCountedPtr<XdsClusterResolverLb> xds_cluster_resolver_lb,
+        size_t index)
+        : parent_(std::move(xds_cluster_resolver_lb)), index_(index) {}
+    virtual void Start() = 0;
+    void Orphan() override = 0;
+
+    // Caller must ensure that config_ is set before calling.
+    const absl::string_view GetXdsClusterResolverResourceName() const {
+      if (!parent_->is_xds_uri_) return parent_->server_name_;
+      if (!parent_->config_->discovery_mechanisms()[index_]
+               .eds_service_name.empty()) {
+        return parent_->config_->discovery_mechanisms()[index_]
+            .eds_service_name;
+      }
+      return parent_->config_->discovery_mechanisms()[index_].cluster_name;
+    }
+
+    // Returns a pair containing the cluster and eds_service_name
+    // to use for LRS load reporting. Caller must ensure that config_ is set
+    // before calling.
+    std::pair<absl::string_view, absl::string_view> GetLrsClusterKey() const {
+      if (!parent_->is_xds_uri_) return {parent_->server_name_, nullptr};
+      return {
+          parent_->config_->discovery_mechanisms()[index_].cluster_name,
+          parent_->config_->discovery_mechanisms()[index_].eds_service_name};
+    }
+
+   protected:
+    XdsClusterResolverLb* parent() const { return parent_.get(); }
+    size_t index() const { return index_; }
+
+   private:
+    RefCountedPtr<XdsClusterResolverLb> parent_;
+    // Stores its own index in the vector of DiscoveryMechanism.
+    size_t index_;
+  };
+
+  class EdsDiscoveryMechanism : public DiscoveryMechanism {
+   public:
+    EdsDiscoveryMechanism(
+        RefCountedPtr<XdsClusterResolverLb> xds_cluster_resolver_lb,
+        size_t index)
+        : DiscoveryMechanism(std::move(xds_cluster_resolver_lb), index) {}
+    void Start() override;
+    void Orphan() override;
+
+   private:
+    class EndpointWatcher : public XdsClient::EndpointWatcherInterface {
+     public:
+      explicit EndpointWatcher(
+          RefCountedPtr<EdsDiscoveryMechanism> discovery_mechanism)
+          : discovery_mechanism_(std::move(discovery_mechanism)) {}
+      ~EndpointWatcher() override {
+        discovery_mechanism_.reset(DEBUG_LOCATION, "EndpointWatcher");
+      }
+      void OnEndpointChanged(XdsApi::EdsUpdate update) override {
+        new Notifier(discovery_mechanism_, std::move(update));
+      }
+      void OnError(grpc_error* error) override {
+        new Notifier(discovery_mechanism_, error);
+      }
+      void OnResourceDoesNotExist() override {
+        new Notifier(discovery_mechanism_);
+      }
+
+     private:
+      class Notifier {
+       public:
+        Notifier(RefCountedPtr<EdsDiscoveryMechanism> discovery_mechanism,
+                 XdsApi::EdsUpdate update);
+        Notifier(RefCountedPtr<EdsDiscoveryMechanism> discovery_mechanism,
+                 grpc_error* error);
+        explicit Notifier(
+            RefCountedPtr<EdsDiscoveryMechanism> discovery_mechanism);
+        ~Notifier() { discovery_mechanism_.reset(DEBUG_LOCATION, "Notifier"); }
+
+       private:
+        enum Type { kUpdate, kError, kDoesNotExist };
+
+        static void RunInExecCtx(void* arg, grpc_error* error);
+        void RunInWorkSerializer(grpc_error* error);
+
+        RefCountedPtr<EdsDiscoveryMechanism> discovery_mechanism_;
+        grpc_closure closure_;
+        XdsApi::EdsUpdate update_;
+        Type type_;
+      };
+
+      RefCountedPtr<EdsDiscoveryMechanism> discovery_mechanism_;
+    };
+
+    // Note that this is not owned, so this pointer must never be dereferenced.
+    EndpointWatcher* watcher_ = nullptr;
+  };
+
+  class LogicalDNSDiscoveryMechanism : public DiscoveryMechanism {
+   public:
+    LogicalDNSDiscoveryMechanism(
+        RefCountedPtr<XdsClusterResolverLb> xds_cluster_resolver_lb,
+        size_t index)
+        : DiscoveryMechanism(std::move(xds_cluster_resolver_lb), index) {}
+    void Start() override;
+    void Orphan() override;
+
+   private:
+    class ResolverResultHandler : public Resolver::ResultHandler {
+     public:
+      explicit ResolverResultHandler(
+          RefCountedPtr<LogicalDNSDiscoveryMechanism> discovery_mechanism)
+          : discovery_mechanism_(std::move(discovery_mechanism)) {}
+
+      ~ResolverResultHandler() override {}
+
+      void ReturnResult(Resolver::Result result) override;
+
+      void ReturnError(grpc_error* error) override;
+
+     private:
+      RefCountedPtr<LogicalDNSDiscoveryMechanism> discovery_mechanism_;
+    };
+    // This is only necessary because of a bug in msvc where nested class cannot
+    // access protected member in base class.
+    friend class ResolverResultHandler;
+    OrphanablePtr<Resolver> resolver_;
+  };
+
+  struct DiscoveryMechanismEntry {
+    OrphanablePtr<DiscoveryMechanism> discovery_mechanism;
+    bool first_update_received = false;
+    // Number of priorities this mechanism has contributed to priority_list_.
+    // (The sum of this across all discovery mechanisms should always equal
+    // the number of priorities in priority_list_.)
+    uint32_t num_priorities = 0;
+    RefCountedPtr<XdsApi::EdsUpdate::DropConfig> drop_config;
+    // Populated only when an update has been delivered by the mechanism
+    // but has not yet been applied to the LB policy's combined priority_list_.
+    absl::optional<XdsApi::EdsUpdate::PriorityList> pending_priority_list;
+  };
+
+  class Helper : public ChannelControlHelper {
+   public:
+    explicit Helper(
+        RefCountedPtr<XdsClusterResolverLb> xds_cluster_resolver_policy)
+        : xds_cluster_resolver_policy_(std::move(xds_cluster_resolver_policy)) {
+    }
+
+    ~Helper() override {
+      xds_cluster_resolver_policy_.reset(DEBUG_LOCATION, "Helper");
+    }
+
+    RefCountedPtr<SubchannelInterface> CreateSubchannel(
+        ServerAddress address, const grpc_channel_args& args) override;
+    void UpdateState(grpc_connectivity_state state, const absl::Status& status,
+                     std::unique_ptr<SubchannelPicker> picker) override;
+    // This is a no-op, because we get the addresses from the xds
+    // client, which is a watch-based API.
+    void RequestReresolution() override {}
+    void AddTraceEvent(TraceSeverity severity,
+                       absl::string_view message) override;
+
+   private:
+    RefCountedPtr<XdsClusterResolverLb> xds_cluster_resolver_policy_;
+  };
+
+  ~XdsClusterResolverLb() override;
+
+  void ShutdownLocked() override;
+
+  void OnEndpointChanged(size_t index, XdsApi::EdsUpdate update);
+  void OnError(size_t index, grpc_error* error);
+  void OnResourceDoesNotExist(size_t index);
+
+  void MaybeDestroyChildPolicyLocked();
+
+  void UpdatePriorityList(XdsApi::EdsUpdate::PriorityList priority_list);
+  void UpdateChildPolicyLocked();
+  OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
+      const grpc_channel_args* args);
+  ServerAddressList CreateChildPolicyAddressesLocked();
+  RefCountedPtr<Config> CreateChildPolicyConfigLocked();
+  grpc_channel_args* CreateChildPolicyArgsLocked(
+      const grpc_channel_args* args_in);
+
+  // Server name from target URI.
+  std::string server_name_;
+  bool is_xds_uri_;
+
+  // Current channel args and config from the resolver.
+  const grpc_channel_args* args_ = nullptr;
+  RefCountedPtr<XdsClusterResolverLbConfig> config_;
+
+  // Internal state.
+  bool shutting_down_ = false;
+
+  // The xds client and endpoint watcher.
+  RefCountedPtr<XdsClient> xds_client_;
+
+  // Vector of discovery mechansism entries in priority order.
+  std::vector<DiscoveryMechanismEntry> discovery_mechanisms_;
+
+  // The latest data from the endpoint watcher.
+  XdsApi::EdsUpdate::PriorityList priority_list_;
+  // State used to retain child policy names for priority policy.
+  std::vector<size_t /*child_number*/> priority_child_numbers_;
+
+  OrphanablePtr<LoadBalancingPolicy> child_policy_;
+};
+
+//
+// XdsClusterResolverLb::Helper
+//
+
+RefCountedPtr<SubchannelInterface>
+XdsClusterResolverLb::Helper::CreateSubchannel(ServerAddress address,
+                                               const grpc_channel_args& args) {
+  if (xds_cluster_resolver_policy_->shutting_down_) return nullptr;
+  return xds_cluster_resolver_policy_->channel_control_helper()
+      ->CreateSubchannel(std::move(address), args);
+}
+
+void XdsClusterResolverLb::Helper::UpdateState(
+    grpc_connectivity_state state, const absl::Status& status,
+    std::unique_ptr<SubchannelPicker> picker) {
+  if (xds_cluster_resolver_policy_->shutting_down_ ||
+      xds_cluster_resolver_policy_->child_policy_ == nullptr) {
+    return;
+  }
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] child policy updated state=%s (%s) "
+            "picker=%p",
+            xds_cluster_resolver_policy_.get(), ConnectivityStateName(state),
+            status.ToString().c_str(), picker.get());
+  }
+  xds_cluster_resolver_policy_->channel_control_helper()->UpdateState(
+      state, status, std::move(picker));
+}
+
+void XdsClusterResolverLb::Helper::AddTraceEvent(TraceSeverity severity,
+                                                 absl::string_view message) {
+  if (xds_cluster_resolver_policy_->shutting_down_) return;
+  xds_cluster_resolver_policy_->channel_control_helper()->AddTraceEvent(
+      severity, message);
+}
+
+//
+// XdsClusterResolverLb::EdsDiscoveryMechanism
+//
+
+void XdsClusterResolverLb::EdsDiscoveryMechanism::Start() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] eds discovery mechanism %" PRIuPTR
+            ":%p starting xds watch for %s",
+            parent(), index(), this,
+            std::string(GetXdsClusterResolverResourceName()).c_str());
+  }
+  auto watcher = absl::make_unique<EndpointWatcher>(
+      Ref(DEBUG_LOCATION, "EdsDiscoveryMechanism"));
+  watcher_ = watcher.get();
+  parent()->xds_client_->WatchEndpointData(GetXdsClusterResolverResourceName(),
+                                           std::move(watcher));
+}
+
+void XdsClusterResolverLb::EdsDiscoveryMechanism::Orphan() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] eds discovery mechanism %" PRIuPTR
+            ":%p cancelling xds watch for %s",
+            parent(), index(), this,
+            std::string(GetXdsClusterResolverResourceName()).c_str());
+  }
+  parent()->xds_client_->CancelEndpointDataWatch(
+      GetXdsClusterResolverResourceName(), watcher_);
+  Unref();
+}
+
+//
+// XdsClusterResolverLb::EndpointWatcher::Notifier
+//
+
+XdsClusterResolverLb::EdsDiscoveryMechanism::EndpointWatcher::Notifier::
+    Notifier(RefCountedPtr<XdsClusterResolverLb::EdsDiscoveryMechanism>
+                 discovery_mechanism,
+             XdsApi::EdsUpdate update)
+    : discovery_mechanism_(std::move(discovery_mechanism)),
+      update_(std::move(update)),
+      type_(kUpdate) {
+  GRPC_CLOSURE_INIT(&closure_, &RunInExecCtx, this, nullptr);
+  ExecCtx::Run(DEBUG_LOCATION, &closure_, GRPC_ERROR_NONE);
+}
+
+XdsClusterResolverLb::EdsDiscoveryMechanism::EndpointWatcher::Notifier::
+    Notifier(RefCountedPtr<XdsClusterResolverLb::EdsDiscoveryMechanism>
+                 discovery_mechanism,
+             grpc_error* error)
+    : discovery_mechanism_(std::move(discovery_mechanism)), type_(kError) {
+  GRPC_CLOSURE_INIT(&closure_, &RunInExecCtx, this, nullptr);
+  ExecCtx::Run(DEBUG_LOCATION, &closure_, error);
+}
+
+XdsClusterResolverLb::EdsDiscoveryMechanism::EndpointWatcher::Notifier::
+    Notifier(RefCountedPtr<XdsClusterResolverLb::EdsDiscoveryMechanism>
+                 discovery_mechanism)
+    : discovery_mechanism_(std::move(discovery_mechanism)),
+      type_(kDoesNotExist) {
+  GRPC_CLOSURE_INIT(&closure_, &RunInExecCtx, this, nullptr);
+  ExecCtx::Run(DEBUG_LOCATION, &closure_, GRPC_ERROR_NONE);
+}
+
+void XdsClusterResolverLb::EdsDiscoveryMechanism::EndpointWatcher::Notifier::
+    RunInExecCtx(void* arg, grpc_error* error) {
+  Notifier* self = static_cast<Notifier*>(arg);
+  GRPC_ERROR_REF(error);
+  self->discovery_mechanism_->parent()->work_serializer()->Run(
+      [self, error]() { self->RunInWorkSerializer(error); }, DEBUG_LOCATION);
+}
+
+void XdsClusterResolverLb::EdsDiscoveryMechanism::EndpointWatcher::Notifier::
+    RunInWorkSerializer(grpc_error* error) {
+  switch (type_) {
+    case kUpdate:
+      discovery_mechanism_->parent()->OnEndpointChanged(
+          discovery_mechanism_->index(), std::move(update_));
+      break;
+    case kError:
+      discovery_mechanism_->parent()->OnError(discovery_mechanism_->index(),
+                                              error);
+      break;
+    case kDoesNotExist:
+      discovery_mechanism_->parent()->OnResourceDoesNotExist(
+          discovery_mechanism_->index());
+      break;
+  };
+  delete this;
+}
+
+//
+// XdsClusterResolverLb::LogicalDNSDiscoveryMechanism
+//
+
+void XdsClusterResolverLb::LogicalDNSDiscoveryMechanism::Start() {
+  resolver_ = ResolverRegistry::CreateResolver(
+      parent()->server_name_.c_str(), parent()->args_,
+      grpc_pollset_set_create(), parent()->work_serializer(),
+      absl::make_unique<ResolverResultHandler>(
+          Ref(DEBUG_LOCATION, "LogicalDNSDiscoveryMechanism")));
+  if (resolver_ == nullptr) {
+    parent()->OnResourceDoesNotExist(index());
+    return;
+  }
+  resolver_->StartLocked();
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] logical DNS discovery mechanism "
+            "%" PRIuPTR ":%p starting dns resolver %p",
+            parent(), index(), this, resolver_.get());
+  }
+}
+
+void XdsClusterResolverLb::LogicalDNSDiscoveryMechanism::Orphan() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(
+        GPR_INFO,
+        "[xds_cluster_resolver_lb %p] logical DNS discovery mechanism %" PRIuPTR
+        ":%p shutting down dns resolver %p",
+        parent(), index(), this, resolver_.get());
+  }
+  resolver_.reset();
+  Unref();
+}
+
+//
+// XdsClusterResolverLb::LogicalDNSDiscoveryMechanism::ResolverResultHandler
+//
+
+void XdsClusterResolverLb::LogicalDNSDiscoveryMechanism::ResolverResultHandler::
+    ReturnResult(Resolver::Result result) {
+  // convert result to eds update
+  XdsApi::EdsUpdate update;
+  XdsApi::EdsUpdate::Priority::Locality locality;
+  locality.name = MakeRefCounted<XdsLocalityName>("", "", "");
+  locality.endpoints = std::move(result.addresses);
+  update.priorities[0].localities.emplace(locality.name.get(),
+                                          std::move(locality));
+  discovery_mechanism_->parent()->OnEndpointChanged(
+      discovery_mechanism_->index(), std::move(update));
+}
+
+void XdsClusterResolverLb::LogicalDNSDiscoveryMechanism::ResolverResultHandler::
+    ReturnError(grpc_error* error) {
+  discovery_mechanism_->parent()->OnError(discovery_mechanism_->index(), error);
+}
+
+//
+// XdsClusterResolverLb public methods
+//
+
+XdsClusterResolverLb::XdsClusterResolverLb(RefCountedPtr<XdsClient> xds_client,
+                                           Args args)
+    : LoadBalancingPolicy(std::move(args)), xds_client_(std::move(xds_client)) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] created -- using xds client %p", this,
+            xds_client_.get());
+  }
+  // Record server name.
+  const char* server_uri =
+      grpc_channel_args_find_string(args.args, GRPC_ARG_SERVER_URI);
+  GPR_ASSERT(server_uri != nullptr);
+  absl::StatusOr<URI> uri = URI::Parse(server_uri);
+  GPR_ASSERT(uri.ok() && !uri->path().empty());
+  server_name_ = std::string(absl::StripPrefix(uri->path(), "/"));
+  is_xds_uri_ = uri->scheme() == "xds";
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] server name from channel "
+            "(is_xds_uri=%d): %s",
+            this, is_xds_uri_, server_name_.c_str());
+  }
+  // EDS-only flow.
+  if (!is_xds_uri_) {
+    // Setup channelz linkage.
+    channelz::ChannelNode* parent_channelz_node =
+        grpc_channel_args_find_pointer<channelz::ChannelNode>(
+            args.args, GRPC_ARG_CHANNELZ_CHANNEL_NODE);
+    if (parent_channelz_node != nullptr) {
+      xds_client_->AddChannelzLinkage(parent_channelz_node);
+    }
+    // Couple polling.
+    grpc_pollset_set_add_pollset_set(xds_client_->interested_parties(),
+                                     interested_parties());
+  }
+}
+
+XdsClusterResolverLb::~XdsClusterResolverLb() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] destroying xds_cluster_resolver LB "
+            "policy",
+            this);
+  }
+}
+
+void XdsClusterResolverLb::ShutdownLocked() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO, "[xds_cluster_resolver_lb %p] shutting down", this);
+  }
+  shutting_down_ = true;
+  MaybeDestroyChildPolicyLocked();
+  discovery_mechanisms_.clear();
+  if (!is_xds_uri_) {
+    // Remove channelz linkage.
+    channelz::ChannelNode* parent_channelz_node =
+        grpc_channel_args_find_pointer<channelz::ChannelNode>(
+            args_, GRPC_ARG_CHANNELZ_CHANNEL_NODE);
+    if (parent_channelz_node != nullptr) {
+      xds_client_->RemoveChannelzLinkage(parent_channelz_node);
+    }
+    // Decouple polling.
+    grpc_pollset_set_del_pollset_set(xds_client_->interested_parties(),
+                                     interested_parties());
+  }
+  xds_client_.reset(DEBUG_LOCATION, "XdsClusterResolverLb");
+  // Destroy channel args.
+  grpc_channel_args_destroy(args_);
+  args_ = nullptr;
+}
+
+void XdsClusterResolverLb::MaybeDestroyChildPolicyLocked() {
+  if (child_policy_ != nullptr) {
+    grpc_pollset_set_del_pollset_set(child_policy_->interested_parties(),
+                                     interested_parties());
+    child_policy_.reset();
+  }
+}
+
+void XdsClusterResolverLb::UpdateLocked(UpdateArgs args) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO, "[xds_cluster_resolver_lb %p] Received update", this);
+  }
+  const bool is_initial_update = args_ == nullptr;
+  // Update config.
+  auto old_config = std::move(config_);
+  config_ = std::move(args.config);
+  // Update args.
+  grpc_channel_args_destroy(args_);
+  args_ = args.args;
+  args.args = nullptr;
+  // Update child policy if needed.
+  if (child_policy_ != nullptr) UpdateChildPolicyLocked();
+  // Create endpoint watcher if needed.
+  if (is_initial_update) {
+    for (const auto& config : config_->discovery_mechanisms()) {
+      DiscoveryMechanismEntry entry;
+      if (config.type == XdsClusterResolverLbConfig::DiscoveryMechanism::
+                             DiscoveryMechanismType::EDS) {
+        entry.discovery_mechanism =
+            grpc_core::MakeOrphanable<EdsDiscoveryMechanism>(
+                Ref(DEBUG_LOCATION, "EdsDiscoveryMechanism"),
+                discovery_mechanisms_.size());
+      } else if (config.type == XdsClusterResolverLbConfig::DiscoveryMechanism::
+                                    DiscoveryMechanismType::LOGICAL_DNS) {
+        entry.discovery_mechanism =
+            grpc_core::MakeOrphanable<LogicalDNSDiscoveryMechanism>(
+                Ref(DEBUG_LOCATION, "LogicalDNSDiscoveryMechanism"),
+                discovery_mechanisms_.size());
+      } else {
+        GPR_ASSERT(0);
+      }
+      discovery_mechanisms_.push_back(std::move(entry));
+    }
+    // Call start() on all discovery mechanisms after creation.
+    for (const auto& discovery_mechanism : discovery_mechanisms_) {
+      discovery_mechanism.discovery_mechanism->Start();
+    }
+  }
+}
+
+void XdsClusterResolverLb::ResetBackoffLocked() {
+  // When the XdsClient is instantiated in the resolver instead of in this
+  // LB policy, this is done via the resolver, so we don't need to do it here.
+  if (!is_xds_uri_ && xds_client_ != nullptr) xds_client_->ResetBackoff();
+  if (child_policy_ != nullptr) {
+    child_policy_->ResetBackoffLocked();
+  }
+}
+
+void XdsClusterResolverLb::OnEndpointChanged(size_t index,
+                                             XdsApi::EdsUpdate update) {
+  if (shutting_down_) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p] Received update from xds client"
+            " for discovery mechanism %" PRIuPTR "",
+            this, index);
+  }
+  // We need at least one priority for each discovery mechanism, just so that we
+  // have a child in which to create the xds_cluster_impl policy.  This ensures
+  // that we properly handle the case of a discovery mechanism dropping 100% of
+  // calls, the OnError() case, and the OnResourceDoesNotExist() case.
+  if (update.priorities.empty()) update.priorities.emplace_back();
+  discovery_mechanisms_[index].drop_config = std::move(update.drop_config);
+  discovery_mechanisms_[index].pending_priority_list =
+      std::move(update.priorities);
+  discovery_mechanisms_[index].first_update_received = true;
+  if (!discovery_mechanisms_[0].first_update_received) {
+    // We have not yet received an update for index 0, so wait until that
+    // happens to create the child policy.
+    return;
+  }
+  // Construct new priority list.
+  XdsApi::EdsUpdate::PriorityList priority_list;
+  size_t priority_index = 0;
+  for (DiscoveryMechanismEntry& mechanism : discovery_mechanisms_) {
+    // If the mechanism has a pending update, use that.
+    // Otherwise, use the priorities that it previously contributed to the
+    // combined list.
+    if (mechanism.pending_priority_list.has_value()) {
+      priority_list.insert(priority_list.end(),
+                           mechanism.pending_priority_list->begin(),
+                           mechanism.pending_priority_list->end());
+      priority_index += mechanism.num_priorities;
+      mechanism.num_priorities = mechanism.pending_priority_list->size();
+      mechanism.pending_priority_list.reset();
+    } else {
+      priority_list.insert(
+          priority_list.end(), priority_list_.begin() + priority_index,
+          priority_list_.begin() + priority_index + mechanism.num_priorities);
+      priority_index += mechanism.num_priorities;
+    }
+  }
+  // Update child policy.
+  UpdatePriorityList(std::move(priority_list));
+}
+
+void XdsClusterResolverLb::OnError(size_t index, grpc_error* error) {
+  gpr_log(GPR_ERROR,
+          "[xds_cluster_resolver_lb %p] discovery mechanism %" PRIuPTR
+          " xds watcher reported error: %s",
+          this, index, grpc_error_string(error));
+  GRPC_ERROR_UNREF(error);
+  if (shutting_down_) return;
+  if (!discovery_mechanisms_[index].first_update_received) {
+    // Call OnEndpointChanged with an empty update just like
+    // OnResourceDoesNotExist.
+    OnEndpointChanged(index, XdsApi::EdsUpdate());
+  }
+}
+
+void XdsClusterResolverLb::OnResourceDoesNotExist(size_t index) {
+  gpr_log(GPR_ERROR,
+          "[xds_cluster_resolver_lb %p] discovery mechanism %" PRIuPTR
+          " resource does not exist",
+          this, index);
+  if (shutting_down_) return;
+  // Call OnEndpointChanged with an empty update.
+  OnEndpointChanged(index, XdsApi::EdsUpdate());
+}
+
+//
+// child policy-related methods
+//
+
+void XdsClusterResolverLb::UpdatePriorityList(
+    XdsApi::EdsUpdate::PriorityList priority_list) {
+  // Build some maps from locality to child number and the reverse from
+  // the old data in priority_list_ and priority_child_numbers_.
+  std::map<XdsLocalityName*, size_t /*child_number*/, XdsLocalityName::Less>
+      locality_child_map;
+  std::map<size_t, std::set<XdsLocalityName*>> child_locality_map;
+  for (size_t priority = 0; priority < priority_list_.size(); ++priority) {
+    size_t child_number = priority_child_numbers_[priority];
+    const auto& localities = priority_list_[priority].localities;
+    for (const auto& p : localities) {
+      XdsLocalityName* locality_name = p.first;
+      locality_child_map[locality_name] = child_number;
+      child_locality_map[child_number].insert(locality_name);
+    }
+  }
+  // Construct new list of children.
+  std::vector<size_t> priority_child_numbers;
+  for (size_t priority = 0; priority < priority_list.size(); ++priority) {
+    const auto& localities = priority_list[priority].localities;
+    absl::optional<size_t> child_number;
+    // If one of the localities in this priority already existed, reuse its
+    // child number.
+    for (const auto& p : localities) {
+      XdsLocalityName* locality_name = p.first;
+      if (!child_number.has_value()) {
+        auto it = locality_child_map.find(locality_name);
+        if (it != locality_child_map.end()) {
+          child_number = it->second;
+          locality_child_map.erase(it);
+          // Remove localities that *used* to be in this child number, so
+          // that we don't incorrectly reuse this child number for a
+          // subsequent priority.
+          for (XdsLocalityName* old_locality :
+               child_locality_map[*child_number]) {
+            locality_child_map.erase(old_locality);
+          }
+        }
+      } else {
+        // Remove all localities that are now in this child number, so
+        // that we don't accidentally reuse this child number for a
+        // subsequent priority.
+        locality_child_map.erase(locality_name);
+      }
+    }
+    // If we didn't find an existing child number, assign a new one.
+    if (!child_number.has_value()) {
+      for (child_number = 0;
+           child_locality_map.find(*child_number) != child_locality_map.end();
+           ++(*child_number)) {
+      }
+      // Add entry so we know that the child number is in use.
+      // (Don't need to add the list of localities, since we won't use them.)
+      child_locality_map[*child_number];
+    }
+    priority_child_numbers.push_back(*child_number);
+  }
+  // Save update.
+  priority_list_ = std::move(priority_list);
+  priority_child_numbers_ = std::move(priority_child_numbers);
+  // Update child policy.
+  UpdateChildPolicyLocked();
+}
+
+ServerAddressList XdsClusterResolverLb::CreateChildPolicyAddressesLocked() {
+  ServerAddressList addresses;
+  for (size_t priority = 0; priority < priority_list_.size(); ++priority) {
+    const auto& localities = priority_list_[priority].localities;
+    std::string priority_child_name =
+        absl::StrCat("child", priority_child_numbers_[priority]);
+    for (const auto& p : localities) {
+      const auto& locality_name = p.first;
+      const auto& locality = p.second;
+      std::vector<std::string> hierarchical_path = {
+          priority_child_name, locality_name->AsHumanReadableString()};
+      for (const auto& endpoint : locality.endpoints) {
+        addresses.emplace_back(
+            endpoint
+                .WithAttribute(kHierarchicalPathAttributeKey,
+                               MakeHierarchicalPathAttribute(hierarchical_path))
+                .WithAttribute(kXdsLocalityNameAttributeKey,
+                               absl::make_unique<XdsLocalityAttribute>(
+                                   locality_name->Ref())));
+      }
+    }
+  }
+  return addresses;
+}
+
+RefCountedPtr<LoadBalancingPolicy::Config>
+XdsClusterResolverLb::CreateChildPolicyConfigLocked() {
+  Json::Object priority_children;
+  Json::Array priority_priorities;
+  // Setting up index to iterate through the discovery mechanisms and keeping
+  // track the discovery_mechanism each prioirty belongs to.
+  size_t discovery_index = 0;
+  // Setting up num_priorities_remaining to track the priorities in each
+  // discovery_mechanism.
+  size_t num_priorities_remaining_in_discovery =
+      discovery_mechanisms_[discovery_index].num_priorities;
+  for (size_t priority = 0; priority < priority_list_.size(); ++priority) {
+    // Each prioirty in the priority_list_ should correspond to a priority in a
+    // discovery mechanism in discovery_mechanisms_ (both in the same order).
+    // Keeping track of the discovery_mechanism each prioirty belongs to.
+    if (num_priorities_remaining_in_discovery == 0) {
+      ++discovery_index;
+      num_priorities_remaining_in_discovery =
+          discovery_mechanisms_[discovery_index].num_priorities;
+    } else {
+      --num_priorities_remaining_in_discovery;
+    }
+    const auto& localities = priority_list_[priority].localities;
+    Json::Object weighted_targets;
+    for (const auto& p : localities) {
+      XdsLocalityName* locality_name = p.first;
+      const auto& locality = p.second;
+      // Construct JSON object containing locality name.
+      Json::Object locality_name_json;
+      if (!locality_name->region().empty()) {
+        locality_name_json["region"] = locality_name->region();
+      }
+      if (!locality_name->zone().empty()) {
+        locality_name_json["zone"] = locality_name->zone();
+      }
+      if (!locality_name->sub_zone().empty()) {
+        locality_name_json["subzone"] = locality_name->sub_zone();
+      }
+      // Add weighted target entry.
+      weighted_targets[locality_name->AsHumanReadableString()] = Json::Object{
+          {"weight", locality.lb_weight},
+          {"childPolicy", config_->endpoint_picking_policy()},
+      };
+    }
+    // Construct locality-picking policy.
+    // Start with field from our config and add the "targets" field.
+    Json locality_picking_config = config_->locality_picking_policy();
+    Json::Object& config =
+        *(*locality_picking_config.mutable_array())[0].mutable_object();
+    auto it = config.begin();
+    GPR_ASSERT(it != config.end());
+    (*it->second.mutable_object())["targets"] = std::move(weighted_targets);
+    // Wrap it in the drop policy.
+    Json::Array drop_categories;
+    if (discovery_mechanisms_[discovery_index].drop_config != nullptr) {
+      for (const auto& category : discovery_mechanisms_[discovery_index]
+                                      .drop_config->drop_category_list()) {
+        drop_categories.push_back(Json::Object{
+            {"category", category.name},
+            {"requests_per_million", category.parts_per_million},
+        });
+      }
+    }
+    const auto lrs_key = discovery_mechanisms_[discovery_index]
+                             .discovery_mechanism->GetLrsClusterKey();
+    Json::Object xds_cluster_impl_config = {
+        {"clusterName", std::string(lrs_key.first)},
+        {"childPolicy", std::move(locality_picking_config)},
+        {"dropCategories", std::move(drop_categories)},
+        {"maxConcurrentRequests",
+         config_->discovery_mechanisms()[discovery_index]
+             .max_concurrent_requests},
+    };
+    if (!lrs_key.second.empty()) {
+      xds_cluster_impl_config["edsServiceName"] = std::string(lrs_key.second);
+    }
+    if (config_->discovery_mechanisms()[discovery_index]
+            .lrs_load_reporting_server_name.has_value()) {
+      xds_cluster_impl_config["lrsLoadReportingServerName"] =
+          config_->discovery_mechanisms()[discovery_index]
+              .lrs_load_reporting_server_name.value();
+    }
+    Json locality_picking_policy = Json::Array{Json::Object{
+        {"xds_cluster_impl_experimental", std::move(xds_cluster_impl_config)},
+    }};
+    // Add priority entry.
+    const size_t child_number = priority_child_numbers_[priority];
+    std::string child_name = absl::StrCat("child", child_number);
+    priority_priorities.emplace_back(child_name);
+    priority_children[child_name] = Json::Object{
+        {"config", std::move(locality_picking_policy)},
+        {"ignore_reresolution_requests", true},
+    };
+  }
+  // There should be matching number of priorities in discovery_mechanisms_ and
+  // in priority_list_; therefore at the end of looping through all the
+  // priorities, num_priorities_remaining should be down to 0, and index should
+  // be the last index in discovery_mechanisms_.
+  GPR_ASSERT(num_priorities_remaining_in_discovery == 0);
+  GPR_ASSERT(discovery_index == discovery_mechanisms_.size() - 1);
+  Json json = Json::Array{Json::Object{
+      {"priority_experimental",
+       Json::Object{
+           {"children", std::move(priority_children)},
+           {"priorities", std::move(priority_priorities)},
+       }},
+  }};
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    std::string json_str = json.Dump(/*indent=*/1);
+    gpr_log(
+        GPR_INFO,
+        "[xds_cluster_resolver_lb %p] generated config for child policy: %s",
+        this, json_str.c_str());
+  }
+  grpc_error* error = GRPC_ERROR_NONE;
+  RefCountedPtr<LoadBalancingPolicy::Config> config =
+      LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(json, &error);
+  if (error != GRPC_ERROR_NONE) {
+    // This should never happen, but if it does, we basically have no
+    // way to fix it, so we put the channel in TRANSIENT_FAILURE.
+    gpr_log(GPR_ERROR,
+            "[xds_cluster_resolver_lb %p] error parsing generated child policy "
+            "config -- "
+            "will put channel in TRANSIENT_FAILURE: %s",
+            this, grpc_error_string(error));
+    error = grpc_error_set_int(
+        grpc_error_add_child(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+                                 "xds_cluster_resolver LB policy: error "
+                                 "parsing generated child policy config"),
+                             error),
+        GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_INTERNAL);
+    channel_control_helper()->UpdateState(
+        GRPC_CHANNEL_TRANSIENT_FAILURE, grpc_error_to_absl_status(error),
+        absl::make_unique<TransientFailurePicker>(error));
+    return nullptr;
+  }
+  return config;
+}
+
+void XdsClusterResolverLb::UpdateChildPolicyLocked() {
+  if (shutting_down_) return;
+  UpdateArgs update_args;
+  update_args.config = CreateChildPolicyConfigLocked();
+  if (update_args.config == nullptr) return;
+  update_args.addresses = CreateChildPolicyAddressesLocked();
+  update_args.args = CreateChildPolicyArgsLocked(args_);
+  if (child_policy_ == nullptr) {
+    child_policy_ = CreateChildPolicyLocked(update_args.args);
+  }
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO, "[xds_cluster_resolver_lb %p] Updating child policy %p",
+            this, child_policy_.get());
+  }
+  child_policy_->UpdateLocked(std::move(update_args));
+}
+
+grpc_channel_args* XdsClusterResolverLb::CreateChildPolicyArgsLocked(
+    const grpc_channel_args* args) {
+  // Inhibit client-side health checking, since the balancer does this for us.
+  grpc_arg new_arg = grpc_channel_arg_integer_create(
+      const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1);
+  return grpc_channel_args_copy_and_add(args, &new_arg, 1);
+}
+
+OrphanablePtr<LoadBalancingPolicy>
+XdsClusterResolverLb::CreateChildPolicyLocked(const grpc_channel_args* args) {
+  LoadBalancingPolicy::Args lb_policy_args;
+  lb_policy_args.work_serializer = work_serializer();
+  lb_policy_args.args = args;
+  lb_policy_args.channel_control_helper =
+      absl::make_unique<Helper>(Ref(DEBUG_LOCATION, "Helper"));
+  OrphanablePtr<LoadBalancingPolicy> lb_policy =
+      LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
+          "priority_experimental", std::move(lb_policy_args));
+  if (GPR_UNLIKELY(lb_policy == nullptr)) {
+    gpr_log(GPR_ERROR,
+            "[xds_cluster_resolver_lb %p] failure creating child policy", this);
+    return nullptr;
+  }
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_cluster_resolver_trace)) {
+    gpr_log(GPR_INFO,
+            "[xds_cluster_resolver_lb %p]: Created new child policy %p", this,
+            lb_policy.get());
+  }
+  // Add our interested_parties pollset_set to that of the newly created
+  // child policy. This will make the child policy progress upon activity on
+  // this policy, which in turn is tied to the application's call.
+  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+                                   interested_parties());
+  return lb_policy;
+}
+
+//
+// factory
+//
+
+class XdsClusterResolverLbFactory : public LoadBalancingPolicyFactory {
+ public:
+  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+      LoadBalancingPolicy::Args args) const override {
+    grpc_error* error = GRPC_ERROR_NONE;
+    RefCountedPtr<XdsClient> xds_client = XdsClient::GetOrCreate(&error);
+    if (error != GRPC_ERROR_NONE) {
+      gpr_log(GPR_ERROR,
+              "cannot get XdsClient to instantiate xds_cluster_resolver LB "
+              "policy: %s",
+              grpc_error_string(error));
+      GRPC_ERROR_UNREF(error);
+      return nullptr;
+    }
+    return MakeOrphanable<XdsClusterResolverChildHandler>(std::move(xds_client),
+                                                          std::move(args));
+  }
+
+  const char* name() const override { return kXdsClusterResolver; }
+
+  RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
+      const Json& json, grpc_error** error) const override {
+    GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
+    if (json.type() == Json::Type::JSON_NULL) {
+      // xds_cluster_resolver was mentioned as a policy in the deprecated
+      // loadBalancingPolicy field or in the client API.
+      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:loadBalancingPolicy error:xds_cluster_resolver policy "
+          "requires configuration. "
+          "Please use loadBalancingConfig field of service config instead.");
+      return nullptr;
+    }
+    std::vector<grpc_error*> error_list;
+    std::vector<XdsClusterResolverLbConfig::DiscoveryMechanism>
+        discovery_mechanisms;
+    auto it = json.object_value().find("discoveryMechanisms");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:discoveryMechanisms error:required field missing"));
+    } else if (it->second.type() != Json::Type::ARRAY) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:discoveryMechanisms error:type should be array"));
+    } else {
+      const Json::Array& array = it->second.array_value();
+      for (size_t i = 0; i < array.size(); ++i) {
+        XdsClusterResolverLbConfig::DiscoveryMechanism discovery_mechanism;
+        std::vector<grpc_error*> discovery_mechanism_errors =
+            ParseDiscoveryMechanism(array[i], &discovery_mechanism);
+        if (!discovery_mechanism_errors.empty()) {
+          grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrCat("field:discovery_mechanism element: ", i, " error")
+                  .c_str());
+          for (grpc_error* discovery_mechanism_error :
+               discovery_mechanism_errors) {
+            error = grpc_error_add_child(error, discovery_mechanism_error);
+          }
+          error_list.push_back(error);
+        }
+        discovery_mechanisms.emplace_back(std::move(discovery_mechanism));
+      }
+    }
+    // Locality-picking policy.
+    Json locality_picking_policy;
+    it = json.object_value().find("localityPickingPolicy");
+    if (it == json.object_value().end()) {
+      locality_picking_policy = Json::Array{
+          Json::Object{
+              {"weighted_target_experimental",
+               Json::Object{
+                   {"targets", Json::Object()},
+               }},
+          },
+      };
+    } else {
+      locality_picking_policy = it->second;
+    }
+    grpc_error* parse_error = GRPC_ERROR_NONE;
+    if (LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+            locality_picking_policy, &parse_error) == nullptr) {
+      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+      error_list.push_back(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+          "localityPickingPolicy", &parse_error, 1));
+      GRPC_ERROR_UNREF(parse_error);
+    }
+    // Endpoint-picking policy.  Called "childPolicy" for xds policy.
+    Json endpoint_picking_policy;
+    it = json.object_value().find("endpointPickingPolicy");
+    if (it == json.object_value().end()) {
+      endpoint_picking_policy = Json::Array{
+          Json::Object{
+              {"round_robin", Json::Object()},
+          },
+      };
+    } else {
+      endpoint_picking_policy = it->second;
+    }
+    parse_error = GRPC_ERROR_NONE;
+    if (LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+            endpoint_picking_policy, &parse_error) == nullptr) {
+      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+      error_list.push_back(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+          "endpointPickingPolicy", &parse_error, 1));
+      GRPC_ERROR_UNREF(parse_error);
+    }
+    if (discovery_mechanisms.empty()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:discovery_mechanism error:list is missing or empty"));
+    }
+    // Construct config.
+    if (error_list.empty()) {
+      return MakeRefCounted<XdsClusterResolverLbConfig>(
+          std::move(discovery_mechanisms), std::move(locality_picking_policy),
+          std::move(endpoint_picking_policy));
+    } else {
+      *error = GRPC_ERROR_CREATE_FROM_VECTOR(
+          "xds_cluster_resolver_experimental LB policy config", &error_list);
+      return nullptr;
+    }
+  }
+
+ private:
+  static std::vector<grpc_error*> ParseDiscoveryMechanism(
+      const Json& json,
+      XdsClusterResolverLbConfig::DiscoveryMechanism* discovery_mechanism) {
+    std::vector<grpc_error*> error_list;
+    if (json.type() != Json::Type::OBJECT) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "value should be of type object"));
+      return error_list;
+    }
+    // Cluster name.
+    auto it = json.object_value().find("clusterName");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:clusterName error:required field missing"));
+    } else if (it->second.type() != Json::Type::STRING) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:clusterName error:type should be string"));
+    } else {
+      discovery_mechanism->cluster_name = it->second.string_value();
+    }
+    // LRS load reporting server name.
+    it = json.object_value().find("lrsLoadReportingServerName");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:lrsLoadReportingServerName error:type should be string"));
+      } else {
+        discovery_mechanism->lrs_load_reporting_server_name.emplace(
+            it->second.string_value());
+      }
+    }
+    // Max concurrent requests.
+    discovery_mechanism->max_concurrent_requests = 1024;
+    it = json.object_value().find("max_concurrent_requests");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::NUMBER) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:max_concurrent_requests error:must be of type number"));
+      } else {
+        discovery_mechanism->max_concurrent_requests =
+            gpr_parse_nonnegative_int(it->second.string_value().c_str());
+      }
+    }
+    // Discovery Mechanism type
+    it = json.object_value().find("type");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:type error:required field missing"));
+    } else if (it->second.type() != Json::Type::STRING) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:type error:type should be string"));
+    } else {
+      if (it->second.string_value() == "EDS") {
+        discovery_mechanism->type = XdsClusterResolverLbConfig::
+            DiscoveryMechanism::DiscoveryMechanismType::EDS;
+      } else if (it->second.string_value() == "LOGICAL_DNS") {
+        discovery_mechanism->type = XdsClusterResolverLbConfig::
+            DiscoveryMechanism::DiscoveryMechanismType::LOGICAL_DNS;
+      } else {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:type error:invalid type"));
+      }
+    }
+    // EDS service name.
+    it = json.object_value().find("edsServiceName");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:xds_cluster_resolverServiceName error:type should be "
+            "string"));
+      } else {
+        discovery_mechanism->eds_service_name = it->second.string_value();
+      }
+    }
+    return error_list;
+  }
+
+  class XdsClusterResolverChildHandler : public ChildPolicyHandler {
+   public:
+    XdsClusterResolverChildHandler(RefCountedPtr<XdsClient> xds_client,
+                                   Args args)
+        : ChildPolicyHandler(std::move(args),
+                             &grpc_lb_xds_cluster_resolver_trace),
+          xds_client_(std::move(xds_client)) {}
+
+    bool ConfigChangeRequiresNewPolicyInstance(
+        LoadBalancingPolicy::Config* old_config,
+        LoadBalancingPolicy::Config* new_config) const override {
+      GPR_ASSERT(old_config->name() == kXdsClusterResolver);
+      GPR_ASSERT(new_config->name() == kXdsClusterResolver);
+      XdsClusterResolverLbConfig* old_xds_cluster_resolver_config =
+          static_cast<XdsClusterResolverLbConfig*>(old_config);
+      XdsClusterResolverLbConfig* new_xds_cluster_resolver_config =
+          static_cast<XdsClusterResolverLbConfig*>(new_config);
+      return old_xds_cluster_resolver_config->discovery_mechanisms() !=
+             new_xds_cluster_resolver_config->discovery_mechanisms();
+    }
+
+    OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+        const char* name, LoadBalancingPolicy::Args args) const override {
+      return MakeOrphanable<XdsClusterResolverLb>(xds_client_, std::move(args));
+    }
+
+   private:
+    RefCountedPtr<XdsClient> xds_client_;
+  };
+};
+
+}  // namespace
+
+}  // namespace grpc_core
+
+//
+// Plugin registration
+//
+
+void grpc_lb_policy_xds_cluster_resolver_init() {
+  grpc_core::LoadBalancingPolicyRegistry::Builder::
+      RegisterLoadBalancingPolicyFactory(
+          absl::make_unique<grpc_core::XdsClusterResolverLbFactory>());
+}
+
+void grpc_lb_policy_xds_cluster_resolver_shutdown() {}

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

@@ -1,485 +0,0 @@
-/*
- *
- * Copyright 2016 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/lib/iomgr/port.h"
-#if GRPC_ARES == 1
-
-#include <ares.h>
-#include <string.h>
-
-#include "absl/strings/str_cat.h"
-
-#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h"
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/time.h>
-#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
-#include "src/core/lib/gpr/string.h"
-#include "src/core/lib/iomgr/iomgr_internal.h"
-#include "src/core/lib/iomgr/sockaddr_utils.h"
-#include "src/core/lib/iomgr/timer.h"
-
-typedef struct fd_node {
-  /** the owner of this fd node */
-  grpc_ares_ev_driver* ev_driver;
-  /** a closure wrapping on_readable_locked, which should be
-     invoked when the grpc_fd in this node becomes readable. */
-  grpc_closure read_closure;
-  /** a closure wrapping on_writable_locked, which should be
-     invoked when the grpc_fd in this node becomes writable. */
-  grpc_closure write_closure;
-  /** next fd node in the list */
-  struct fd_node* next;
-
-  /** wrapped fd that's polled by grpc's poller for the current platform */
-  grpc_core::GrpcPolledFd* grpc_polled_fd;
-  /** if the readable closure has been registered */
-  bool readable_registered;
-  /** if the writable closure has been registered */
-  bool writable_registered;
-  /** if the fd has been shutdown yet from grpc iomgr perspective */
-  bool already_shutdown;
-} fd_node;
-
-struct grpc_ares_ev_driver {
-  /** the ares_channel owned by this event driver */
-  ares_channel channel;
-  /** pollset set for driving the IO events of the channel */
-  grpc_pollset_set* pollset_set;
-  /** refcount of the event driver */
-  gpr_refcount refs;
-
-  /** work_serializer to synchronize c-ares and I/O callbacks on */
-  std::shared_ptr<grpc_core::WorkSerializer> work_serializer;
-  /** a list of grpc_fd that this event driver is currently using. */
-  fd_node* fds;
-  /** is this event driver currently working? */
-  bool working;
-  /** is this event driver being shut down */
-  bool shutting_down;
-  /** request object that's using this ev driver */
-  grpc_ares_request* request;
-  /** Owned by the ev_driver. Creates new GrpcPolledFd's */
-  std::unique_ptr<grpc_core::GrpcPolledFdFactory> polled_fd_factory;
-  /** query timeout in milliseconds */
-  int query_timeout_ms;
-  /** alarm to cancel active queries */
-  grpc_timer query_timeout;
-  /** cancels queries on a timeout */
-  grpc_closure on_timeout_locked;
-  /** alarm to poll ares_process on in case fd events don't happen */
-  grpc_timer ares_backup_poll_alarm;
-  /** polls ares_process on a periodic timer */
-  grpc_closure on_ares_backup_poll_alarm_locked;
-};
-
-static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver);
-
-static grpc_ares_ev_driver* grpc_ares_ev_driver_ref(
-    grpc_ares_ev_driver* ev_driver) {
-  GRPC_CARES_TRACE_LOG("request:%p Ref ev_driver %p", ev_driver->request,
-                       ev_driver);
-  gpr_ref(&ev_driver->refs);
-  return ev_driver;
-}
-
-static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver* ev_driver) {
-  GRPC_CARES_TRACE_LOG("request:%p Unref ev_driver %p", ev_driver->request,
-                       ev_driver);
-  if (gpr_unref(&ev_driver->refs)) {
-    GRPC_CARES_TRACE_LOG("request:%p destroy ev_driver %p", ev_driver->request,
-                         ev_driver);
-    GPR_ASSERT(ev_driver->fds == nullptr);
-    ares_destroy(ev_driver->channel);
-    grpc_ares_complete_request_locked(ev_driver->request);
-    delete ev_driver;
-  }
-}
-
-static void fd_node_destroy_locked(fd_node* fdn) {
-  GRPC_CARES_TRACE_LOG("request:%p delete fd: %s", fdn->ev_driver->request,
-                       fdn->grpc_polled_fd->GetName());
-  GPR_ASSERT(!fdn->readable_registered);
-  GPR_ASSERT(!fdn->writable_registered);
-  GPR_ASSERT(fdn->already_shutdown);
-  delete fdn->grpc_polled_fd;
-  gpr_free(fdn);
-}
-
-static void fd_node_shutdown_locked(fd_node* fdn, const char* reason) {
-  if (!fdn->already_shutdown) {
-    fdn->already_shutdown = true;
-    fdn->grpc_polled_fd->ShutdownLocked(
-        GRPC_ERROR_CREATE_FROM_STATIC_STRING(reason));
-  }
-}
-
-static void on_timeout(void* arg, grpc_error* error);
-static void on_timeout_locked(grpc_ares_ev_driver* driver, grpc_error* error);
-
-static void on_ares_backup_poll_alarm(void* arg, grpc_error* error);
-static void on_ares_backup_poll_alarm_locked(grpc_ares_ev_driver* driver,
-                                             grpc_error* error);
-
-static void noop_inject_channel_config(ares_channel /*channel*/) {}
-
-void (*grpc_ares_test_only_inject_config)(ares_channel channel) =
-    noop_inject_channel_config;
-
-grpc_error* grpc_ares_ev_driver_create_locked(
-    grpc_ares_ev_driver** ev_driver, grpc_pollset_set* pollset_set,
-    int query_timeout_ms,
-    std::shared_ptr<grpc_core::WorkSerializer> work_serializer,
-    grpc_ares_request* request) {
-  *ev_driver = new grpc_ares_ev_driver();
-  ares_options opts;
-  memset(&opts, 0, sizeof(opts));
-  opts.flags |= ARES_FLAG_STAYOPEN;
-  int status = ares_init_options(&(*ev_driver)->channel, &opts, ARES_OPT_FLAGS);
-  grpc_ares_test_only_inject_config((*ev_driver)->channel);
-  GRPC_CARES_TRACE_LOG("request:%p grpc_ares_ev_driver_create_locked", request);
-  if (status != ARES_SUCCESS) {
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
-        absl::StrCat("Failed to init ares channel. C-ares error: ",
-                     ares_strerror(status))
-            .c_str());
-    gpr_free(*ev_driver);
-    return err;
-  }
-  (*ev_driver)->work_serializer = std::move(work_serializer);
-  gpr_ref_init(&(*ev_driver)->refs, 1);
-  (*ev_driver)->pollset_set = pollset_set;
-  (*ev_driver)->fds = nullptr;
-  (*ev_driver)->working = false;
-  (*ev_driver)->shutting_down = false;
-  (*ev_driver)->request = request;
-  (*ev_driver)->polled_fd_factory =
-      grpc_core::NewGrpcPolledFdFactory((*ev_driver)->work_serializer);
-  (*ev_driver)
-      ->polled_fd_factory->ConfigureAresChannelLocked((*ev_driver)->channel);
-  (*ev_driver)->query_timeout_ms = query_timeout_ms;
-  return GRPC_ERROR_NONE;
-}
-
-void grpc_ares_ev_driver_on_queries_complete_locked(
-    grpc_ares_ev_driver* ev_driver) {
-  // We mark the event driver as being shut down. If the event driver
-  // is working, grpc_ares_notify_on_event_locked will shut down the
-  // fds; if it's not working, there are no fds to shut down.
-  ev_driver->shutting_down = true;
-  grpc_timer_cancel(&ev_driver->query_timeout);
-  grpc_timer_cancel(&ev_driver->ares_backup_poll_alarm);
-  grpc_ares_ev_driver_unref(ev_driver);
-}
-
-void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver) {
-  ev_driver->shutting_down = true;
-  fd_node* fn = ev_driver->fds;
-  while (fn != nullptr) {
-    fd_node_shutdown_locked(fn, "grpc_ares_ev_driver_shutdown");
-    fn = fn->next;
-  }
-}
-
-// Search fd in the fd_node list head. This is an O(n) search, the max possible
-// value of n is ARES_GETSOCK_MAXNUM (16). n is typically 1 - 2 in our tests.
-static fd_node* pop_fd_node_locked(fd_node** head, ares_socket_t as) {
-  fd_node dummy_head;
-  dummy_head.next = *head;
-  fd_node* node = &dummy_head;
-  while (node->next != nullptr) {
-    if (node->next->grpc_polled_fd->GetWrappedAresSocketLocked() == as) {
-      fd_node* ret = node->next;
-      node->next = node->next->next;
-      *head = dummy_head.next;
-      return ret;
-    }
-    node = node->next;
-  }
-  return nullptr;
-}
-
-static grpc_millis calculate_next_ares_backup_poll_alarm_ms(
-    grpc_ares_ev_driver* driver) {
-  // An alternative here could be to use ares_timeout to try to be more
-  // accurate, but that would require using "struct timeval"'s, which just makes
-  // things a bit more complicated. So just poll every second, as suggested
-  // by the c-ares code comments.
-  grpc_millis ms_until_next_ares_backup_poll_alarm = 1000;
-  GRPC_CARES_TRACE_LOG(
-      "request:%p ev_driver=%p. next ares process poll time in "
-      "%" PRId64 " ms",
-      driver->request, driver, ms_until_next_ares_backup_poll_alarm);
-  return ms_until_next_ares_backup_poll_alarm +
-         grpc_core::ExecCtx::Get()->Now();
-}
-
-static void on_timeout(void* arg, grpc_error* error) {
-  grpc_ares_ev_driver* driver = static_cast<grpc_ares_ev_driver*>(arg);
-  GRPC_ERROR_REF(error);  // ref owned by lambda
-  driver->work_serializer->Run(
-      [driver, error]() { on_timeout_locked(driver, error); }, DEBUG_LOCATION);
-}
-
-static void on_timeout_locked(grpc_ares_ev_driver* driver, grpc_error* error) {
-  GRPC_CARES_TRACE_LOG(
-      "request:%p ev_driver=%p on_timeout_locked. driver->shutting_down=%d. "
-      "err=%s",
-      driver->request, driver, driver->shutting_down, grpc_error_string(error));
-  if (!driver->shutting_down && error == GRPC_ERROR_NONE) {
-    grpc_ares_ev_driver_shutdown_locked(driver);
-  }
-  grpc_ares_ev_driver_unref(driver);
-  GRPC_ERROR_UNREF(error);
-}
-
-static void on_ares_backup_poll_alarm(void* arg, grpc_error* error) {
-  grpc_ares_ev_driver* driver = static_cast<grpc_ares_ev_driver*>(arg);
-  GRPC_ERROR_REF(error);
-  driver->work_serializer->Run(
-      [driver, error]() { on_ares_backup_poll_alarm_locked(driver, error); },
-      DEBUG_LOCATION);
-}
-
-/* In case of non-responsive DNS servers, dropped packets, etc., c-ares has
- * intelligent timeout and retry logic, which we can take advantage of by
- * polling ares_process_fd on time intervals. Overall, the c-ares library is
- * meant to be called into and given a chance to proceed name resolution:
- *   a) when fd events happen
- *   b) when some time has passed without fd events having happened
- * For the latter, we use this backup poller. Also see
- * https://github.com/grpc/grpc/pull/17688 description for more details. */
-static void on_ares_backup_poll_alarm_locked(grpc_ares_ev_driver* driver,
-                                             grpc_error* error) {
-  GRPC_CARES_TRACE_LOG(
-      "request:%p ev_driver=%p on_ares_backup_poll_alarm_locked. "
-      "driver->shutting_down=%d. "
-      "err=%s",
-      driver->request, driver, driver->shutting_down, grpc_error_string(error));
-  if (!driver->shutting_down && error == GRPC_ERROR_NONE) {
-    fd_node* fdn = driver->fds;
-    while (fdn != nullptr) {
-      if (!fdn->already_shutdown) {
-        GRPC_CARES_TRACE_LOG(
-            "request:%p ev_driver=%p on_ares_backup_poll_alarm_locked; "
-            "ares_process_fd. fd=%s",
-            driver->request, driver, fdn->grpc_polled_fd->GetName());
-        ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
-        ares_process_fd(driver->channel, as, as);
-      }
-      fdn = fdn->next;
-    }
-    if (!driver->shutting_down) {
-      grpc_millis next_ares_backup_poll_alarm =
-          calculate_next_ares_backup_poll_alarm_ms(driver);
-      grpc_ares_ev_driver_ref(driver);
-      GRPC_CLOSURE_INIT(&driver->on_ares_backup_poll_alarm_locked,
-                        on_ares_backup_poll_alarm, driver,
-                        grpc_schedule_on_exec_ctx);
-      grpc_timer_init(&driver->ares_backup_poll_alarm,
-                      next_ares_backup_poll_alarm,
-                      &driver->on_ares_backup_poll_alarm_locked);
-    }
-    grpc_ares_notify_on_event_locked(driver);
-  }
-  grpc_ares_ev_driver_unref(driver);
-  GRPC_ERROR_UNREF(error);
-}
-
-static void on_readable_locked(fd_node* fdn, grpc_error* error) {
-  GPR_ASSERT(fdn->readable_registered);
-  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
-  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
-  fdn->readable_registered = false;
-  GRPC_CARES_TRACE_LOG("request:%p readable on %s", fdn->ev_driver->request,
-                       fdn->grpc_polled_fd->GetName());
-  if (error == GRPC_ERROR_NONE) {
-    do {
-      ares_process_fd(ev_driver->channel, as, ARES_SOCKET_BAD);
-    } while (fdn->grpc_polled_fd->IsFdStillReadableLocked());
-  } else {
-    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
-    // timed out. The pending lookups made on this ev_driver will be cancelled
-    // by the following ares_cancel() and the on_done callbacks will be invoked
-    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
-    // ev_driver will be cleaned up in the follwing
-    // grpc_ares_notify_on_event_locked().
-    ares_cancel(ev_driver->channel);
-  }
-  grpc_ares_notify_on_event_locked(ev_driver);
-  grpc_ares_ev_driver_unref(ev_driver);
-  GRPC_ERROR_UNREF(error);
-}
-
-static void on_readable(void* arg, grpc_error* error) {
-  fd_node* fdn = static_cast<fd_node*>(arg);
-  GRPC_ERROR_REF(error); /* ref owned by lambda */
-  fdn->ev_driver->work_serializer->Run(
-      [fdn, error]() { on_readable_locked(fdn, error); }, DEBUG_LOCATION);
-}
-
-static void on_writable_locked(fd_node* fdn, grpc_error* error) {
-  GPR_ASSERT(fdn->writable_registered);
-  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
-  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
-  fdn->writable_registered = false;
-  GRPC_CARES_TRACE_LOG("request:%p writable on %s", ev_driver->request,
-                       fdn->grpc_polled_fd->GetName());
-  if (error == GRPC_ERROR_NONE) {
-    ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, as);
-  } else {
-    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
-    // timed out. The pending lookups made on this ev_driver will be cancelled
-    // by the following ares_cancel() and the on_done callbacks will be invoked
-    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
-    // ev_driver will be cleaned up in the follwing
-    // grpc_ares_notify_on_event_locked().
-    ares_cancel(ev_driver->channel);
-  }
-  grpc_ares_notify_on_event_locked(ev_driver);
-  grpc_ares_ev_driver_unref(ev_driver);
-  GRPC_ERROR_UNREF(error);
-}
-
-static void on_writable(void* arg, grpc_error* error) {
-  fd_node* fdn = static_cast<fd_node*>(arg);
-  GRPC_ERROR_REF(error); /* ref owned by lambda */
-  fdn->ev_driver->work_serializer->Run(
-      [fdn, error]() { on_writable_locked(fdn, error); }, DEBUG_LOCATION);
-}
-
-ares_channel* grpc_ares_ev_driver_get_channel_locked(
-    grpc_ares_ev_driver* ev_driver) {
-  return &ev_driver->channel;
-}
-
-// Get the file descriptors used by the ev_driver's ares channel, register
-// driver_closure with these filedescriptors.
-static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver) {
-  fd_node* new_list = nullptr;
-  if (!ev_driver->shutting_down) {
-    ares_socket_t socks[ARES_GETSOCK_MAXNUM];
-    int socks_bitmask =
-        ares_getsock(ev_driver->channel, socks, ARES_GETSOCK_MAXNUM);
-    for (size_t i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
-      if (ARES_GETSOCK_READABLE(socks_bitmask, i) ||
-          ARES_GETSOCK_WRITABLE(socks_bitmask, i)) {
-        fd_node* fdn = pop_fd_node_locked(&ev_driver->fds, socks[i]);
-        // Create a new fd_node if sock[i] is not in the fd_node list.
-        if (fdn == nullptr) {
-          fdn = static_cast<fd_node*>(gpr_malloc(sizeof(fd_node)));
-          fdn->grpc_polled_fd =
-              ev_driver->polled_fd_factory->NewGrpcPolledFdLocked(
-                  socks[i], ev_driver->pollset_set, ev_driver->work_serializer);
-          GRPC_CARES_TRACE_LOG("request:%p new fd: %s", ev_driver->request,
-                               fdn->grpc_polled_fd->GetName());
-          fdn->ev_driver = ev_driver;
-          fdn->readable_registered = false;
-          fdn->writable_registered = false;
-          fdn->already_shutdown = false;
-        }
-        fdn->next = new_list;
-        new_list = fdn;
-        // Register read_closure if the socket is readable and read_closure has
-        // not been registered with this socket.
-        if (ARES_GETSOCK_READABLE(socks_bitmask, i) &&
-            !fdn->readable_registered) {
-          grpc_ares_ev_driver_ref(ev_driver);
-          GRPC_CARES_TRACE_LOG("request:%p notify read on: %s",
-                               ev_driver->request,
-                               fdn->grpc_polled_fd->GetName());
-          GRPC_CLOSURE_INIT(&fdn->read_closure, on_readable, fdn,
-                            grpc_schedule_on_exec_ctx);
-          fdn->grpc_polled_fd->RegisterForOnReadableLocked(&fdn->read_closure);
-          fdn->readable_registered = true;
-        }
-        // Register write_closure if the socket is writable and write_closure
-        // has not been registered with this socket.
-        if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) &&
-            !fdn->writable_registered) {
-          GRPC_CARES_TRACE_LOG("request:%p notify write on: %s",
-                               ev_driver->request,
-                               fdn->grpc_polled_fd->GetName());
-          grpc_ares_ev_driver_ref(ev_driver);
-          GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable, fdn,
-                            grpc_schedule_on_exec_ctx);
-          fdn->grpc_polled_fd->RegisterForOnWriteableLocked(
-              &fdn->write_closure);
-          fdn->writable_registered = true;
-        }
-      }
-    }
-  }
-  // Any remaining fds in ev_driver->fds were not returned by ares_getsock() and
-  // are therefore no longer in use, so they can be shut down and removed from
-  // the list.
-  while (ev_driver->fds != nullptr) {
-    fd_node* cur = ev_driver->fds;
-    ev_driver->fds = ev_driver->fds->next;
-    fd_node_shutdown_locked(cur, "c-ares fd shutdown");
-    if (!cur->readable_registered && !cur->writable_registered) {
-      fd_node_destroy_locked(cur);
-    } else {
-      cur->next = new_list;
-      new_list = cur;
-    }
-  }
-  ev_driver->fds = new_list;
-  // If the ev driver has no working fd, all the tasks are done.
-  if (new_list == nullptr) {
-    ev_driver->working = false;
-    GRPC_CARES_TRACE_LOG("request:%p ev driver stop working",
-                         ev_driver->request);
-  }
-}
-
-void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver) {
-  if (!ev_driver->working) {
-    ev_driver->working = true;
-    grpc_ares_notify_on_event_locked(ev_driver);
-    // Initialize overall DNS resolution timeout alarm
-    grpc_millis timeout =
-        ev_driver->query_timeout_ms == 0
-            ? GRPC_MILLIS_INF_FUTURE
-            : ev_driver->query_timeout_ms + grpc_core::ExecCtx::Get()->Now();
-    GRPC_CARES_TRACE_LOG(
-        "request:%p ev_driver=%p grpc_ares_ev_driver_start_locked. timeout in "
-        "%" PRId64 " ms",
-        ev_driver->request, ev_driver, timeout);
-    grpc_ares_ev_driver_ref(ev_driver);
-    GRPC_CLOSURE_INIT(&ev_driver->on_timeout_locked, on_timeout, ev_driver,
-                      grpc_schedule_on_exec_ctx);
-    grpc_timer_init(&ev_driver->query_timeout, timeout,
-                    &ev_driver->on_timeout_locked);
-    // Initialize the backup poll alarm
-    grpc_millis next_ares_backup_poll_alarm =
-        calculate_next_ares_backup_poll_alarm_ms(ev_driver);
-    grpc_ares_ev_driver_ref(ev_driver);
-    GRPC_CLOSURE_INIT(&ev_driver->on_ares_backup_poll_alarm_locked,
-                      on_ares_backup_poll_alarm, ev_driver,
-                      grpc_schedule_on_exec_ctx);
-    grpc_timer_init(&ev_driver->ares_backup_poll_alarm,
-                    next_ares_backup_poll_alarm,
-                    &ev_driver->on_ares_backup_poll_alarm_locked);
-  }
-}
-
-#endif /* GRPC_ARES == 1 */

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

@@ -22,39 +22,8 @@
 #include <grpc/support/port_platform.h>
 
 #include <ares.h>
-#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
 #include "src/core/lib/iomgr/pollset_set.h"
-
-typedef struct grpc_ares_ev_driver grpc_ares_ev_driver;
-
-/* Start \a ev_driver. It will keep working until all IO on its ares_channel is
-   done, or grpc_ares_ev_driver_destroy() is called. It may notify the callbacks
-   bound to its ares_channel when necessary. */
-void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver);
-
-/* Returns the ares_channel owned by \a ev_driver. To bind a c-ares query to
-   \a ev_driver, use the ares_channel owned by \a ev_driver as the arg of the
-   query. */
-ares_channel* grpc_ares_ev_driver_get_channel_locked(
-    grpc_ares_ev_driver* ev_driver);
-
-/* Creates a new grpc_ares_ev_driver. Returns GRPC_ERROR_NONE if \a ev_driver is
-   created successfully. */
-grpc_error* grpc_ares_ev_driver_create_locked(
-    grpc_ares_ev_driver** ev_driver, grpc_pollset_set* pollset_set,
-    int query_timeout_ms,
-    std::shared_ptr<grpc_core::WorkSerializer> work_serializer,
-    grpc_ares_request* request);
-
-/* Called back when all DNS lookups have completed. */
-void grpc_ares_ev_driver_on_queries_complete_locked(
-    grpc_ares_ev_driver* ev_driver);
-
-/* Shutdown all the grpc_fds used by \a ev_driver */
-void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver);
-
-/* Exposed in this header for C-core tests only */
-extern void (*grpc_ares_test_only_inject_config)(ares_channel channel);
+#include "src/core/lib/iomgr/work_serializer.h"
 
 namespace grpc_core {
 

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

@@ -46,6 +46,7 @@
 #include "src/core/lib/iomgr/nameser.h"
 #include "src/core/lib/iomgr/parse_address.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
+#include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/transport/authority_override.h"
 
 using grpc_core::ServerAddress;
@@ -56,6 +57,8 @@ grpc_core::TraceFlag grpc_trace_cares_address_sorting(false,
 
 grpc_core::TraceFlag grpc_trace_cares_resolver(false, "cares_resolver");
 
+typedef struct grpc_ares_ev_driver grpc_ares_ev_driver;
+
 struct grpc_ares_request {
   /** indicates the DNS server to use, if specified */
   struct ares_addr_port_node dns_server_addr;
@@ -77,6 +80,60 @@ struct grpc_ares_request {
   grpc_error* error;
 };
 
+typedef struct fd_node {
+  /** the owner of this fd node */
+  grpc_ares_ev_driver* ev_driver;
+  /** a closure wrapping on_readable_locked, which should be
+     invoked when the grpc_fd in this node becomes readable. */
+  grpc_closure read_closure;
+  /** a closure wrapping on_writable_locked, which should be
+     invoked when the grpc_fd in this node becomes writable. */
+  grpc_closure write_closure;
+  /** next fd node in the list */
+  struct fd_node* next;
+
+  /** wrapped fd that's polled by grpc's poller for the current platform */
+  grpc_core::GrpcPolledFd* grpc_polled_fd;
+  /** if the readable closure has been registered */
+  bool readable_registered;
+  /** if the writable closure has been registered */
+  bool writable_registered;
+  /** if the fd has been shutdown yet from grpc iomgr perspective */
+  bool already_shutdown;
+} fd_node;
+
+struct grpc_ares_ev_driver {
+  /** the ares_channel owned by this event driver */
+  ares_channel channel;
+  /** pollset set for driving the IO events of the channel */
+  grpc_pollset_set* pollset_set;
+  /** refcount of the event driver */
+  gpr_refcount refs;
+
+  /** work_serializer to synchronize c-ares and I/O callbacks on */
+  std::shared_ptr<grpc_core::WorkSerializer> work_serializer;
+  /** a list of grpc_fd that this event driver is currently using. */
+  fd_node* fds;
+  /** is this event driver currently working? */
+  bool working;
+  /** is this event driver being shut down */
+  bool shutting_down;
+  /** request object that's using this ev driver */
+  grpc_ares_request* request;
+  /** Owned by the ev_driver. Creates new GrpcPolledFd's */
+  std::unique_ptr<grpc_core::GrpcPolledFdFactory> polled_fd_factory;
+  /** query timeout in milliseconds */
+  int query_timeout_ms;
+  /** alarm to cancel active queries */
+  grpc_timer query_timeout;
+  /** cancels queries on a timeout */
+  grpc_closure on_timeout_locked;
+  /** alarm to poll ares_process on in case fd events don't happen */
+  grpc_timer ares_backup_poll_alarm;
+  /** polls ares_process on a periodic timer */
+  grpc_closure on_ares_backup_poll_alarm_locked;
+};
+
 // TODO(apolcyn): make grpc_ares_hostbyname_request a sub-class
 // of GrpcAresQuery.
 typedef struct grpc_ares_hostbyname_request {
@@ -121,6 +178,390 @@ class GrpcAresQuery {
   const std::string name_;
 };
 
+static grpc_ares_ev_driver* grpc_ares_ev_driver_ref(
+    grpc_ares_ev_driver* ev_driver) {
+  GRPC_CARES_TRACE_LOG("request:%p Ref ev_driver %p", ev_driver->request,
+                       ev_driver);
+  gpr_ref(&ev_driver->refs);
+  return ev_driver;
+}
+
+static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver* ev_driver) {
+  GRPC_CARES_TRACE_LOG("request:%p Unref ev_driver %p", ev_driver->request,
+                       ev_driver);
+  if (gpr_unref(&ev_driver->refs)) {
+    GRPC_CARES_TRACE_LOG("request:%p destroy ev_driver %p", ev_driver->request,
+                         ev_driver);
+    GPR_ASSERT(ev_driver->fds == nullptr);
+    ares_destroy(ev_driver->channel);
+    grpc_ares_complete_request_locked(ev_driver->request);
+    delete ev_driver;
+  }
+}
+
+static void fd_node_destroy_locked(fd_node* fdn) {
+  GRPC_CARES_TRACE_LOG("request:%p delete fd: %s", fdn->ev_driver->request,
+                       fdn->grpc_polled_fd->GetName());
+  GPR_ASSERT(!fdn->readable_registered);
+  GPR_ASSERT(!fdn->writable_registered);
+  GPR_ASSERT(fdn->already_shutdown);
+  delete fdn->grpc_polled_fd;
+  gpr_free(fdn);
+}
+
+static void fd_node_shutdown_locked(fd_node* fdn, const char* reason) {
+  if (!fdn->already_shutdown) {
+    fdn->already_shutdown = true;
+    fdn->grpc_polled_fd->ShutdownLocked(
+        GRPC_ERROR_CREATE_FROM_STATIC_STRING(reason));
+  }
+}
+
+void grpc_ares_ev_driver_on_queries_complete_locked(
+    grpc_ares_ev_driver* ev_driver) {
+  // We mark the event driver as being shut down. If the event driver
+  // is working, grpc_ares_notify_on_event_locked will shut down the
+  // fds; if it's not working, there are no fds to shut down.
+  ev_driver->shutting_down = true;
+  grpc_timer_cancel(&ev_driver->query_timeout);
+  grpc_timer_cancel(&ev_driver->ares_backup_poll_alarm);
+  grpc_ares_ev_driver_unref(ev_driver);
+}
+
+void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver) {
+  ev_driver->shutting_down = true;
+  fd_node* fn = ev_driver->fds;
+  while (fn != nullptr) {
+    fd_node_shutdown_locked(fn, "grpc_ares_ev_driver_shutdown");
+    fn = fn->next;
+  }
+}
+
+// Search fd in the fd_node list head. This is an O(n) search, the max possible
+// value of n is ARES_GETSOCK_MAXNUM (16). n is typically 1 - 2 in our tests.
+static fd_node* pop_fd_node_locked(fd_node** head, ares_socket_t as) {
+  fd_node dummy_head;
+  dummy_head.next = *head;
+  fd_node* node = &dummy_head;
+  while (node->next != nullptr) {
+    if (node->next->grpc_polled_fd->GetWrappedAresSocketLocked() == as) {
+      fd_node* ret = node->next;
+      node->next = node->next->next;
+      *head = dummy_head.next;
+      return ret;
+    }
+    node = node->next;
+  }
+  return nullptr;
+}
+
+static grpc_millis calculate_next_ares_backup_poll_alarm_ms(
+    grpc_ares_ev_driver* driver) {
+  // An alternative here could be to use ares_timeout to try to be more
+  // accurate, but that would require using "struct timeval"'s, which just makes
+  // things a bit more complicated. So just poll every second, as suggested
+  // by the c-ares code comments.
+  grpc_millis ms_until_next_ares_backup_poll_alarm = 1000;
+  GRPC_CARES_TRACE_LOG(
+      "request:%p ev_driver=%p. next ares process poll time in "
+      "%" PRId64 " ms",
+      driver->request, driver, ms_until_next_ares_backup_poll_alarm);
+  return ms_until_next_ares_backup_poll_alarm +
+         grpc_core::ExecCtx::Get()->Now();
+}
+
+static void on_timeout_locked(grpc_ares_ev_driver* driver, grpc_error* error) {
+  GRPC_CARES_TRACE_LOG(
+      "request:%p ev_driver=%p on_timeout_locked. driver->shutting_down=%d. "
+      "err=%s",
+      driver->request, driver, driver->shutting_down, grpc_error_string(error));
+  if (!driver->shutting_down && error == GRPC_ERROR_NONE) {
+    grpc_ares_ev_driver_shutdown_locked(driver);
+  }
+  grpc_ares_ev_driver_unref(driver);
+  GRPC_ERROR_UNREF(error);
+}
+
+static void on_timeout(void* arg, grpc_error* error) {
+  grpc_ares_ev_driver* driver = static_cast<grpc_ares_ev_driver*>(arg);
+  GRPC_ERROR_REF(error);  // ref owned by lambda
+  driver->work_serializer->Run(
+      [driver, error]() { on_timeout_locked(driver, error); }, DEBUG_LOCATION);
+}
+
+static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver);
+
+static void on_ares_backup_poll_alarm_locked(grpc_ares_ev_driver* driver,
+                                             grpc_error* error);
+
+static void on_ares_backup_poll_alarm(void* arg, grpc_error* error) {
+  grpc_ares_ev_driver* driver = static_cast<grpc_ares_ev_driver*>(arg);
+  GRPC_ERROR_REF(error);
+  driver->work_serializer->Run(
+      [driver, error]() { on_ares_backup_poll_alarm_locked(driver, error); },
+      DEBUG_LOCATION);
+}
+
+/* In case of non-responsive DNS servers, dropped packets, etc., c-ares has
+ * intelligent timeout and retry logic, which we can take advantage of by
+ * polling ares_process_fd on time intervals. Overall, the c-ares library is
+ * meant to be called into and given a chance to proceed name resolution:
+ *   a) when fd events happen
+ *   b) when some time has passed without fd events having happened
+ * For the latter, we use this backup poller. Also see
+ * https://github.com/grpc/grpc/pull/17688 description for more details. */
+static void on_ares_backup_poll_alarm_locked(grpc_ares_ev_driver* driver,
+                                             grpc_error* error) {
+  GRPC_CARES_TRACE_LOG(
+      "request:%p ev_driver=%p on_ares_backup_poll_alarm_locked. "
+      "driver->shutting_down=%d. "
+      "err=%s",
+      driver->request, driver, driver->shutting_down, grpc_error_string(error));
+  if (!driver->shutting_down && error == GRPC_ERROR_NONE) {
+    fd_node* fdn = driver->fds;
+    while (fdn != nullptr) {
+      if (!fdn->already_shutdown) {
+        GRPC_CARES_TRACE_LOG(
+            "request:%p ev_driver=%p on_ares_backup_poll_alarm_locked; "
+            "ares_process_fd. fd=%s",
+            driver->request, driver, fdn->grpc_polled_fd->GetName());
+        ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
+        ares_process_fd(driver->channel, as, as);
+      }
+      fdn = fdn->next;
+    }
+    if (!driver->shutting_down) {
+      grpc_millis next_ares_backup_poll_alarm =
+          calculate_next_ares_backup_poll_alarm_ms(driver);
+      grpc_ares_ev_driver_ref(driver);
+      GRPC_CLOSURE_INIT(&driver->on_ares_backup_poll_alarm_locked,
+                        on_ares_backup_poll_alarm, driver,
+                        grpc_schedule_on_exec_ctx);
+      grpc_timer_init(&driver->ares_backup_poll_alarm,
+                      next_ares_backup_poll_alarm,
+                      &driver->on_ares_backup_poll_alarm_locked);
+    }
+    grpc_ares_notify_on_event_locked(driver);
+  }
+  grpc_ares_ev_driver_unref(driver);
+  GRPC_ERROR_UNREF(error);
+}
+
+static void on_readable_locked(fd_node* fdn, grpc_error* error) {
+  GPR_ASSERT(fdn->readable_registered);
+  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
+  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
+  fdn->readable_registered = false;
+  GRPC_CARES_TRACE_LOG("request:%p readable on %s", fdn->ev_driver->request,
+                       fdn->grpc_polled_fd->GetName());
+  if (error == GRPC_ERROR_NONE) {
+    do {
+      ares_process_fd(ev_driver->channel, as, ARES_SOCKET_BAD);
+    } while (fdn->grpc_polled_fd->IsFdStillReadableLocked());
+  } else {
+    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
+    // timed out. The pending lookups made on this ev_driver will be cancelled
+    // by the following ares_cancel() and the on_done callbacks will be invoked
+    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
+    // ev_driver will be cleaned up in the follwing
+    // grpc_ares_notify_on_event_locked().
+    ares_cancel(ev_driver->channel);
+  }
+  grpc_ares_notify_on_event_locked(ev_driver);
+  grpc_ares_ev_driver_unref(ev_driver);
+  GRPC_ERROR_UNREF(error);
+}
+
+static void on_readable(void* arg, grpc_error* error) {
+  fd_node* fdn = static_cast<fd_node*>(arg);
+  GRPC_ERROR_REF(error); /* ref owned by lambda */
+  fdn->ev_driver->work_serializer->Run(
+      [fdn, error]() { on_readable_locked(fdn, error); }, DEBUG_LOCATION);
+}
+
+static void on_writable_locked(fd_node* fdn, grpc_error* error) {
+  GPR_ASSERT(fdn->writable_registered);
+  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
+  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
+  fdn->writable_registered = false;
+  GRPC_CARES_TRACE_LOG("request:%p writable on %s", ev_driver->request,
+                       fdn->grpc_polled_fd->GetName());
+  if (error == GRPC_ERROR_NONE) {
+    ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, as);
+  } else {
+    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
+    // timed out. The pending lookups made on this ev_driver will be cancelled
+    // by the following ares_cancel() and the on_done callbacks will be invoked
+    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
+    // ev_driver will be cleaned up in the follwing
+    // grpc_ares_notify_on_event_locked().
+    ares_cancel(ev_driver->channel);
+  }
+  grpc_ares_notify_on_event_locked(ev_driver);
+  grpc_ares_ev_driver_unref(ev_driver);
+  GRPC_ERROR_UNREF(error);
+}
+
+static void on_writable(void* arg, grpc_error* error) {
+  fd_node* fdn = static_cast<fd_node*>(arg);
+  GRPC_ERROR_REF(error); /* ref owned by lambda */
+  fdn->ev_driver->work_serializer->Run(
+      [fdn, error]() { on_writable_locked(fdn, error); }, DEBUG_LOCATION);
+}
+
+// Get the file descriptors used by the ev_driver's ares channel, register
+// driver_closure with these filedescriptors.
+static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver) {
+  fd_node* new_list = nullptr;
+  if (!ev_driver->shutting_down) {
+    ares_socket_t socks[ARES_GETSOCK_MAXNUM];
+    int socks_bitmask =
+        ares_getsock(ev_driver->channel, socks, ARES_GETSOCK_MAXNUM);
+    for (size_t i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
+      if (ARES_GETSOCK_READABLE(socks_bitmask, i) ||
+          ARES_GETSOCK_WRITABLE(socks_bitmask, i)) {
+        fd_node* fdn = pop_fd_node_locked(&ev_driver->fds, socks[i]);
+        // Create a new fd_node if sock[i] is not in the fd_node list.
+        if (fdn == nullptr) {
+          fdn = static_cast<fd_node*>(gpr_malloc(sizeof(fd_node)));
+          fdn->grpc_polled_fd =
+              ev_driver->polled_fd_factory->NewGrpcPolledFdLocked(
+                  socks[i], ev_driver->pollset_set, ev_driver->work_serializer);
+          GRPC_CARES_TRACE_LOG("request:%p new fd: %s", ev_driver->request,
+                               fdn->grpc_polled_fd->GetName());
+          fdn->ev_driver = ev_driver;
+          fdn->readable_registered = false;
+          fdn->writable_registered = false;
+          fdn->already_shutdown = false;
+        }
+        fdn->next = new_list;
+        new_list = fdn;
+        // Register read_closure if the socket is readable and read_closure has
+        // not been registered with this socket.
+        if (ARES_GETSOCK_READABLE(socks_bitmask, i) &&
+            !fdn->readable_registered) {
+          grpc_ares_ev_driver_ref(ev_driver);
+          GRPC_CARES_TRACE_LOG("request:%p notify read on: %s",
+                               ev_driver->request,
+                               fdn->grpc_polled_fd->GetName());
+          GRPC_CLOSURE_INIT(&fdn->read_closure, on_readable, fdn,
+                            grpc_schedule_on_exec_ctx);
+          fdn->grpc_polled_fd->RegisterForOnReadableLocked(&fdn->read_closure);
+          fdn->readable_registered = true;
+        }
+        // Register write_closure if the socket is writable and write_closure
+        // has not been registered with this socket.
+        if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) &&
+            !fdn->writable_registered) {
+          GRPC_CARES_TRACE_LOG("request:%p notify write on: %s",
+                               ev_driver->request,
+                               fdn->grpc_polled_fd->GetName());
+          grpc_ares_ev_driver_ref(ev_driver);
+          GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable, fdn,
+                            grpc_schedule_on_exec_ctx);
+          GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable, fdn,
+                            grpc_schedule_on_exec_ctx);
+          fdn->grpc_polled_fd->RegisterForOnWriteableLocked(
+              &fdn->write_closure);
+          fdn->writable_registered = true;
+        }
+      }
+    }
+  }
+  // Any remaining fds in ev_driver->fds were not returned by ares_getsock() and
+  // are therefore no longer in use, so they can be shut down and removed from
+  // the list.
+  while (ev_driver->fds != nullptr) {
+    fd_node* cur = ev_driver->fds;
+    ev_driver->fds = ev_driver->fds->next;
+    fd_node_shutdown_locked(cur, "c-ares fd shutdown");
+    if (!cur->readable_registered && !cur->writable_registered) {
+      fd_node_destroy_locked(cur);
+    } else {
+      cur->next = new_list;
+      new_list = cur;
+    }
+  }
+  ev_driver->fds = new_list;
+  // If the ev driver has no working fd, all the tasks are done.
+  if (new_list == nullptr) {
+    ev_driver->working = false;
+    GRPC_CARES_TRACE_LOG("request:%p ev driver stop working",
+                         ev_driver->request);
+  }
+}
+
+void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver) {
+  if (!ev_driver->working) {
+    ev_driver->working = true;
+    grpc_ares_notify_on_event_locked(ev_driver);
+    // Initialize overall DNS resolution timeout alarm
+    grpc_millis timeout =
+        ev_driver->query_timeout_ms == 0
+            ? GRPC_MILLIS_INF_FUTURE
+            : ev_driver->query_timeout_ms + grpc_core::ExecCtx::Get()->Now();
+    GRPC_CARES_TRACE_LOG(
+        "request:%p ev_driver=%p grpc_ares_ev_driver_start_locked. timeout in "
+        "%" PRId64 " ms",
+        ev_driver->request, ev_driver, timeout);
+    grpc_ares_ev_driver_ref(ev_driver);
+    GRPC_CLOSURE_INIT(&ev_driver->on_timeout_locked, on_timeout, ev_driver,
+                      grpc_schedule_on_exec_ctx);
+    grpc_timer_init(&ev_driver->query_timeout, timeout,
+                    &ev_driver->on_timeout_locked);
+    // Initialize the backup poll alarm
+    grpc_millis next_ares_backup_poll_alarm =
+        calculate_next_ares_backup_poll_alarm_ms(ev_driver);
+    grpc_ares_ev_driver_ref(ev_driver);
+    GRPC_CLOSURE_INIT(&ev_driver->on_ares_backup_poll_alarm_locked,
+                      on_ares_backup_poll_alarm, ev_driver,
+                      grpc_schedule_on_exec_ctx);
+    grpc_timer_init(&ev_driver->ares_backup_poll_alarm,
+                    next_ares_backup_poll_alarm,
+                    &ev_driver->on_ares_backup_poll_alarm_locked);
+  }
+}
+
+static void noop_inject_channel_config(ares_channel /*channel*/) {}
+
+void (*grpc_ares_test_only_inject_config)(ares_channel channel) =
+    noop_inject_channel_config;
+
+grpc_error* grpc_ares_ev_driver_create_locked(
+    grpc_ares_ev_driver** ev_driver, grpc_pollset_set* pollset_set,
+    int query_timeout_ms,
+    std::shared_ptr<grpc_core::WorkSerializer> work_serializer,
+    grpc_ares_request* request) {
+  *ev_driver = new grpc_ares_ev_driver();
+  ares_options opts;
+  memset(&opts, 0, sizeof(opts));
+  opts.flags |= ARES_FLAG_STAYOPEN;
+  int status = ares_init_options(&(*ev_driver)->channel, &opts, ARES_OPT_FLAGS);
+  grpc_ares_test_only_inject_config((*ev_driver)->channel);
+  GRPC_CARES_TRACE_LOG("request:%p grpc_ares_ev_driver_create_locked", request);
+  if (status != ARES_SUCCESS) {
+    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Failed to init ares channel. C-ares error: ",
+                     ares_strerror(status))
+            .c_str());
+    gpr_free(*ev_driver);
+    return err;
+  }
+  (*ev_driver)->work_serializer = std::move(work_serializer);
+  gpr_ref_init(&(*ev_driver)->refs, 1);
+  (*ev_driver)->pollset_set = pollset_set;
+  (*ev_driver)->fds = nullptr;
+  (*ev_driver)->working = false;
+  (*ev_driver)->shutting_down = false;
+  (*ev_driver)->request = request;
+  (*ev_driver)->polled_fd_factory =
+      grpc_core::NewGrpcPolledFdFactory((*ev_driver)->work_serializer);
+  (*ev_driver)
+      ->polled_fd_factory->ConfigureAresChannelLocked((*ev_driver)->channel);
+  (*ev_driver)->query_timeout_ms = query_timeout_ms;
+  return GRPC_ERROR_NONE;
+}
+
 static void log_address_sorting_list(const grpc_ares_request* r,
                                      const ServerAddressList& addresses,
                                      const char* input_output_str) {
@@ -303,20 +744,18 @@ static void on_srv_query_done_locked(void* arg, int status, int /*timeouts*/,
     GRPC_CARES_TRACE_LOG("request:%p ares_parse_srv_reply: %d", r,
                          parse_status);
     if (parse_status == ARES_SUCCESS) {
-      ares_channel* channel =
-          grpc_ares_ev_driver_get_channel_locked(r->ev_driver);
       for (struct ares_srv_reply* srv_it = reply; srv_it != nullptr;
            srv_it = srv_it->next) {
         if (grpc_ares_query_ipv6()) {
           grpc_ares_hostbyname_request* hr = create_hostbyname_request_locked(
               r, srv_it->host, htons(srv_it->port), true /* is_balancer */,
               "AAAA");
-          ares_gethostbyname(*channel, hr->host, AF_INET6,
+          ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET6,
                              on_hostbyname_done_locked, hr);
         }
         grpc_ares_hostbyname_request* hr = create_hostbyname_request_locked(
             r, srv_it->host, htons(srv_it->port), true /* is_balancer */, "A");
-        ares_gethostbyname(*channel, hr->host, AF_INET,
+        ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET,
                            on_hostbyname_done_locked, hr);
         grpc_ares_ev_driver_start_locked(r->ev_driver);
       }
@@ -400,7 +839,6 @@ void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
     std::shared_ptr<grpc_core::WorkSerializer> work_serializer) {
   grpc_error* error = GRPC_ERROR_NONE;
   grpc_ares_hostbyname_request* hr = nullptr;
-  ares_channel* channel = nullptr;
   /* parse name, splitting it into host and port parts */
   std::string host;
   std::string port;
@@ -423,7 +861,6 @@ void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
                                             query_timeout_ms,
                                             std::move(work_serializer), r);
   if (error != GRPC_ERROR_NONE) goto error_cleanup;
-  channel = grpc_ares_ev_driver_get_channel_locked(r->ev_driver);
   // If dns_server is specified, use it.
   if (dns_server != nullptr && dns_server[0] != '\0') {
     GRPC_CARES_TRACE_LOG("request:%p Using DNS server %s", r, dns_server);
@@ -450,7 +887,8 @@ void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
           GRPC_ERROR_STR_TARGET_ADDRESS, grpc_slice_from_copied_string(name));
       goto error_cleanup;
     }
-    int status = ares_set_servers_ports(*channel, &r->dns_server_addr);
+    int status =
+        ares_set_servers_ports(r->ev_driver->channel, &r->dns_server_addr);
     if (status != ARES_SUCCESS) {
       error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
           absl::StrCat("C-ares status is not ARES_SUCCESS: ",
@@ -464,25 +902,25 @@ void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
     hr = create_hostbyname_request_locked(r, host.c_str(),
                                           grpc_strhtons(port.c_str()),
                                           /*is_balancer=*/false, "AAAA");
-    ares_gethostbyname(*channel, hr->host, AF_INET6, on_hostbyname_done_locked,
-                       hr);
+    ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET6,
+                       on_hostbyname_done_locked, hr);
   }
   hr = create_hostbyname_request_locked(r, host.c_str(),
                                         grpc_strhtons(port.c_str()),
                                         /*is_balancer=*/false, "A");
-  ares_gethostbyname(*channel, hr->host, AF_INET, on_hostbyname_done_locked,
-                     hr);
+  ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET,
+                     on_hostbyname_done_locked, hr);
   if (r->balancer_addresses_out != nullptr) {
     /* Query the SRV record */
     std::string service_name = absl::StrCat("_grpclb._tcp.", host);
     GrpcAresQuery* srv_query = new GrpcAresQuery(r, service_name);
-    ares_query(*channel, service_name.c_str(), ns_c_in, ns_t_srv,
+    ares_query(r->ev_driver->channel, service_name.c_str(), ns_c_in, ns_t_srv,
                on_srv_query_done_locked, srv_query);
   }
   if (r->service_config_json_out != nullptr) {
     std::string config_name = absl::StrCat("_grpc_config.", host);
     GrpcAresQuery* txt_query = new GrpcAresQuery(r, config_name);
-    ares_search(*channel, config_name.c_str(), ns_c_in, ns_t_txt,
+    ares_search(r->ev_driver->channel, config_name.c_str(), ns_c_in, ns_t_txt,
                 on_txt_done_locked, txt_query);
   }
   grpc_ares_ev_driver_start_locked(r->ev_driver);

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

@@ -21,6 +21,8 @@
 
 #include <grpc/support/port_platform.h>
 
+#include <ares.h>
+
 #include "src/core/ext/filters/client_channel/server_address.h"
 #include "src/core/lib/iomgr/iomgr.h"
 #include "src/core/lib/iomgr/polling_entity.h"
@@ -93,5 +95,8 @@ bool grpc_ares_query_ipv6();
 void grpc_cares_wrapper_address_sorting_sort(
     const grpc_ares_request* request, grpc_core::ServerAddressList* addresses);
 
+/* Exposed in this header for C-core tests only */
+extern void (*grpc_ares_test_only_inject_config)(ares_channel channel);
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_WRAPPER_H \
         */

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

@@ -1,68 +0,0 @@
-/*
- *
- * Copyright 2016-2017 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>
-
-#if GRPC_ARES != 1
-
-#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
-
-struct grpc_ares_request {
-  char val;
-};
-
-static grpc_ares_request* grpc_dns_lookup_ares_locked_impl(
-    const char* dns_server, const char* name, const char* default_port,
-    grpc_pollset_set* interested_parties, grpc_closure* on_done,
-    std::unique_ptr<grpc_core::ServerAddressList>* addrs,
-    std::unique_ptr<grpc_core::ServerAddressList>* balancer_addrs,
-    char** service_config_json, int query_timeout_ms,
-    std::shared_ptr<grpc_core::WorkSerializer> work_serializer) {
-  return NULL;
-}
-
-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,
-    std::unique_ptr<grpc_core::ServerAddressList>* addrs,
-    std::unique_ptr<grpc_core::ServerAddressList>* balancer_addrs,
-    char** service_config_json, int query_timeout_ms,
-    std::shared_ptr<grpc_core::WorkSerializer> work_serializer) =
-    grpc_dns_lookup_ares_locked_impl;
-
-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; }
-
-void grpc_ares_cleanup(void) {}
-
-static void grpc_resolve_address_ares_impl(const char* name,
-                                           const char* default_port,
-                                           grpc_pollset_set* interested_parties,
-                                           grpc_closure* on_done,
-                                           grpc_resolved_addresses** addrs) {}
-
-void (*grpc_resolve_address_ares)(
-    const char* name, const char* default_port,
-    grpc_pollset_set* interested_parties, grpc_closure* on_done,
-    grpc_resolved_addresses** addrs) = grpc_resolve_address_ares_impl;
-
-#endif /* GRPC_ARES != 1 */

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

@@ -248,27 +248,25 @@ grpc_error* ParseRetryThrottling(
   return GRPC_ERROR_CREATE_FROM_VECTOR("retryPolicy", &error_list);
 }
 
-const char* ParseHealthCheckConfig(const Json& field, grpc_error** error) {
+absl::optional<std::string> ParseHealthCheckConfig(const Json& field,
+                                                   grpc_error** error) {
   GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
-  const char* service_name = nullptr;
   if (field.type() != Json::Type::OBJECT) {
     *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
         "field:healthCheckConfig error:should be of type object");
-    return nullptr;
+    return absl::nullopt;
   }
   std::vector<grpc_error*> error_list;
+  absl::optional<std::string> service_name;
   auto it = field.object_value().find("serviceName");
   if (it != field.object_value().end()) {
     if (it->second.type() != Json::Type::STRING) {
       error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
           "field:serviceName error:should be of type string"));
     } else {
-      service_name = it->second.string_value().c_str();
+      service_name = it->second.string_value();
     }
   }
-  if (!error_list.empty()) {
-    return nullptr;
-  }
   *error =
       GRPC_ERROR_CREATE_FROM_VECTOR("field:healthCheckConfig", &error_list);
   return service_name;
@@ -281,12 +279,8 @@ ClientChannelServiceConfigParser::ParseGlobalParams(
     const grpc_channel_args* /*args*/, const Json& json, grpc_error** error) {
   GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
   std::vector<grpc_error*> error_list;
-  RefCountedPtr<LoadBalancingPolicy::Config> parsed_lb_config;
-  std::string lb_policy_name;
-  absl::optional<ClientChannelGlobalParsedConfig::RetryThrottling>
-      retry_throttling;
-  const char* health_check_service_name = nullptr;
   // Parse LB config.
+  RefCountedPtr<LoadBalancingPolicy::Config> parsed_lb_config;
   auto it = json.object_value().find("loadBalancingConfig");
   if (it != json.object_value().end()) {
     grpc_error* parse_error = GRPC_ERROR_NONE;
@@ -300,6 +294,7 @@ ClientChannelServiceConfigParser::ParseGlobalParams(
     }
   }
   // Parse deprecated LB policy.
+  std::string lb_policy_name;
   it = json.object_value().find("loadBalancingPolicy");
   if (it != json.object_value().end()) {
     if (it->second.type() != Json::Type::STRING) {
@@ -325,6 +320,8 @@ ClientChannelServiceConfigParser::ParseGlobalParams(
     }
   }
   // Parse retry throttling.
+  absl::optional<ClientChannelGlobalParsedConfig::RetryThrottling>
+      retry_throttling;
   it = json.object_value().find("retryThrottling");
   if (it != json.object_value().end()) {
     ClientChannelGlobalParsedConfig::RetryThrottling data;
@@ -336,6 +333,7 @@ ClientChannelServiceConfigParser::ParseGlobalParams(
     }
   }
   // Parse health check config.
+  absl::optional<std::string> health_check_service_name;
   it = json.object_value().find("healthCheckConfig");
   if (it != json.object_value().end()) {
     grpc_error* parsing_error = GRPC_ERROR_NONE;
@@ -350,7 +348,7 @@ ClientChannelServiceConfigParser::ParseGlobalParams(
   if (*error == GRPC_ERROR_NONE) {
     return absl::make_unique<ClientChannelGlobalParsedConfig>(
         std::move(parsed_lb_config), std::move(lb_policy_name),
-        retry_throttling, health_check_service_name);
+        retry_throttling, std::move(health_check_service_name));
   }
   return nullptr;
 }