Merge branch 'master' of github.com:grpc/grpc into grpclb_api

# Conflicts:
#	BUILD
#	Makefile
#	binding.gyp
#	build.yaml
#	gRPC.podspec
#	tools/doxygen/Doxyfile.core.internal
#	tools/run_tests/sources_and_headers.json
#	vsprojects/vcxproj/grpc/grpc.vcxproj
#	vsprojects/vcxproj/grpc/grpc.vcxproj.filters
#	vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
#	vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters

.gitignore

@@ -38,6 +38,7 @@ cache.mk
 # Temporary test reports
 report.xml
 latency_trace.txt
+latency_trace.*.txt
 
 # port server log
 portlog.txt

BUILD

@@ -57,6 +57,7 @@ cc_library(
     "src/core/profiling/basic_timers.c",
     "src/core/profiling/stap_timers.c",
     "src/core/support/alloc.c",
+    "src/core/support/avl.c",
     "src/core/support/cmdline.c",
     "src/core/support/cpu_iphone.c",
     "src/core/support/cpu_linux.c",
@@ -101,6 +102,7 @@ cc_library(
     "include/grpc/support/atm_gcc_atomic.h",
     "include/grpc/support/atm_gcc_sync.h",
     "include/grpc/support/atm_win32.h",
+    "include/grpc/support/avl.h",
     "include/grpc/support/cmdline.h",
     "include/grpc/support/cpu.h",
     "include/grpc/support/histogram.h",
@@ -160,8 +162,10 @@ cc_library(
     "src/core/channel/http_client_filter.h",
     "src/core/channel/http_server_filter.h",
     "src/core/channel/noop_filter.h",
+    "src/core/channel/subchannel_call_holder.h",
     "src/core/client_config/client_config.h",
     "src/core/client_config/connector.h",
+    "src/core/client_config/initial_connect_string.h",
     "src/core/client_config/lb_policies/load_balancer_api.h",
     "src/core/client_config/lb_policies/pick_first.h",
     "src/core/client_config/lb_policies/round_robin.h",
@@ -178,6 +182,7 @@ cc_library(
     "src/core/client_config/subchannel_factory_decorators/add_channel_arg.h",
     "src/core/client_config/subchannel_factory_decorators/merge_channel_args.h",
     "src/core/client_config/uri_parser.h",
+    "src/core/compression/algorithm_metadata.h",
     "src/core/compression/message_compress.h",
     "src/core/debug/trace.h",
     "src/core/httpcli/format_request.h",
@@ -228,7 +233,6 @@ cc_library(
     "src/core/statistics/census_interface.h",
     "src/core/statistics/census_rpc_stats.h",
     "src/core/surface/api_trace.h",
-    "src/core/surface/byte_buffer_queue.h",
     "src/core/surface/call.h",
     "src/core/surface/call_test_only.h",
     "src/core/surface/channel.h",
@@ -237,6 +241,7 @@ cc_library(
     "src/core/surface/init.h",
     "src/core/surface/server.h",
     "src/core/surface/surface_trace.h",
+    "src/core/transport/byte_stream.h",
     "src/core/transport/chttp2/alpn.h",
     "src/core/transport/chttp2/bin_encoder.h",
     "src/core/transport/chttp2/frame.h",
@@ -246,6 +251,7 @@ cc_library(
     "src/core/transport/chttp2/frame_rst_stream.h",
     "src/core/transport/chttp2/frame_settings.h",
     "src/core/transport/chttp2/frame_window_update.h",
+    "src/core/transport/chttp2/hpack_encoder.h",
     "src/core/transport/chttp2/hpack_parser.h",
     "src/core/transport/chttp2/hpack_table.h",
     "src/core/transport/chttp2/http2_errors.h",
@@ -253,14 +259,14 @@ cc_library(
     "src/core/transport/chttp2/incoming_metadata.h",
     "src/core/transport/chttp2/internal.h",
     "src/core/transport/chttp2/status_conversion.h",
-    "src/core/transport/chttp2/stream_encoder.h",
     "src/core/transport/chttp2/stream_map.h",
     "src/core/transport/chttp2/timeout_encoding.h",
     "src/core/transport/chttp2/varint.h",
     "src/core/transport/chttp2_transport.h",
     "src/core/transport/connectivity_state.h",
     "src/core/transport/metadata.h",
-    "src/core/transport/stream_op.h",
+    "src/core/transport/metadata_batch.h",
+    "src/core/transport/static_metadata.h",
     "src/core/transport/transport.h",
     "src/core/transport/transport_impl.h",
     "third_party/nanopb/pb.h",
@@ -302,8 +308,11 @@ cc_library(
     "src/core/channel/http_client_filter.c",
     "src/core/channel/http_server_filter.c",
     "src/core/channel/noop_filter.c",
+    "src/core/channel/subchannel_call_holder.c",
     "src/core/client_config/client_config.c",
     "src/core/client_config/connector.c",
+    "src/core/client_config/default_initial_connect_string.c",
+    "src/core/client_config/initial_connect_string.c",
     "src/core/client_config/lb_policies/load_balancer_api.c",
     "src/core/client_config/lb_policies/pick_first.c",
     "src/core/client_config/lb_policies/round_robin.c",
@@ -373,7 +382,6 @@ cc_library(
     "src/core/proto/load_balancer.pb.c",
     "src/core/surface/api_trace.c",
     "src/core/surface/byte_buffer.c",
-    "src/core/surface/byte_buffer_queue.c",
     "src/core/surface/byte_buffer_reader.c",
     "src/core/surface/call.c",
     "src/core/surface/call_details.c",
@@ -390,6 +398,7 @@ cc_library(
     "src/core/surface/server_chttp2.c",
     "src/core/surface/server_create.c",
     "src/core/surface/version.c",
+    "src/core/transport/byte_stream.c",
     "src/core/transport/chttp2/alpn.c",
     "src/core/transport/chttp2/bin_encoder.c",
     "src/core/transport/chttp2/frame_data.c",
@@ -398,13 +407,13 @@ cc_library(
     "src/core/transport/chttp2/frame_rst_stream.c",
     "src/core/transport/chttp2/frame_settings.c",
     "src/core/transport/chttp2/frame_window_update.c",
+    "src/core/transport/chttp2/hpack_encoder.c",
     "src/core/transport/chttp2/hpack_parser.c",
     "src/core/transport/chttp2/hpack_table.c",
     "src/core/transport/chttp2/huffsyms.c",
     "src/core/transport/chttp2/incoming_metadata.c",
     "src/core/transport/chttp2/parsing.c",
     "src/core/transport/chttp2/status_conversion.c",
-    "src/core/transport/chttp2/stream_encoder.c",
     "src/core/transport/chttp2/stream_lists.c",
     "src/core/transport/chttp2/stream_map.c",
     "src/core/transport/chttp2/timeout_encoding.c",
@@ -413,7 +422,8 @@ cc_library(
     "src/core/transport/chttp2_transport.c",
     "src/core/transport/connectivity_state.c",
     "src/core/transport/metadata.c",
-    "src/core/transport/stream_op.c",
+    "src/core/transport/metadata_batch.c",
+    "src/core/transport/static_metadata.c",
     "src/core/transport/transport.c",
     "src/core/transport/transport_op_string.c",
     "third_party/nanopb/pb_common.c",
@@ -459,8 +469,10 @@ cc_library(
     "src/core/channel/http_client_filter.h",
     "src/core/channel/http_server_filter.h",
     "src/core/channel/noop_filter.h",
+    "src/core/channel/subchannel_call_holder.h",
     "src/core/client_config/client_config.h",
     "src/core/client_config/connector.h",
+    "src/core/client_config/initial_connect_string.h",
     "src/core/client_config/lb_policies/load_balancer_api.h",
     "src/core/client_config/lb_policies/pick_first.h",
     "src/core/client_config/lb_policies/round_robin.h",
@@ -477,6 +489,7 @@ cc_library(
     "src/core/client_config/subchannel_factory_decorators/add_channel_arg.h",
     "src/core/client_config/subchannel_factory_decorators/merge_channel_args.h",
     "src/core/client_config/uri_parser.h",
+    "src/core/compression/algorithm_metadata.h",
     "src/core/compression/message_compress.h",
     "src/core/debug/trace.h",
     "src/core/httpcli/format_request.h",
@@ -527,7 +540,6 @@ cc_library(
     "src/core/statistics/census_interface.h",
     "src/core/statistics/census_rpc_stats.h",
     "src/core/surface/api_trace.h",
-    "src/core/surface/byte_buffer_queue.h",
     "src/core/surface/call.h",
     "src/core/surface/call_test_only.h",
     "src/core/surface/channel.h",
@@ -536,6 +548,7 @@ cc_library(
     "src/core/surface/init.h",
     "src/core/surface/server.h",
     "src/core/surface/surface_trace.h",
+    "src/core/transport/byte_stream.h",
     "src/core/transport/chttp2/alpn.h",
     "src/core/transport/chttp2/bin_encoder.h",
     "src/core/transport/chttp2/frame.h",
@@ -545,6 +558,7 @@ cc_library(
     "src/core/transport/chttp2/frame_rst_stream.h",
     "src/core/transport/chttp2/frame_settings.h",
     "src/core/transport/chttp2/frame_window_update.h",
+    "src/core/transport/chttp2/hpack_encoder.h",
     "src/core/transport/chttp2/hpack_parser.h",
     "src/core/transport/chttp2/hpack_table.h",
     "src/core/transport/chttp2/http2_errors.h",
@@ -552,14 +566,14 @@ cc_library(
     "src/core/transport/chttp2/incoming_metadata.h",
     "src/core/transport/chttp2/internal.h",
     "src/core/transport/chttp2/status_conversion.h",
-    "src/core/transport/chttp2/stream_encoder.h",
     "src/core/transport/chttp2/stream_map.h",
     "src/core/transport/chttp2/timeout_encoding.h",
     "src/core/transport/chttp2/varint.h",
     "src/core/transport/chttp2_transport.h",
     "src/core/transport/connectivity_state.h",
     "src/core/transport/metadata.h",
-    "src/core/transport/stream_op.h",
+    "src/core/transport/metadata_batch.h",
+    "src/core/transport/static_metadata.h",
     "src/core/transport/transport.h",
     "src/core/transport/transport_impl.h",
     "third_party/nanopb/pb.h",
@@ -581,8 +595,11 @@ cc_library(
     "src/core/channel/http_client_filter.c",
     "src/core/channel/http_server_filter.c",
     "src/core/channel/noop_filter.c",
+    "src/core/channel/subchannel_call_holder.c",
     "src/core/client_config/client_config.c",
     "src/core/client_config/connector.c",
+    "src/core/client_config/default_initial_connect_string.c",
+    "src/core/client_config/initial_connect_string.c",
     "src/core/client_config/lb_policies/load_balancer_api.c",
     "src/core/client_config/lb_policies/pick_first.c",
     "src/core/client_config/lb_policies/round_robin.c",
@@ -652,7 +669,6 @@ cc_library(
     "src/core/proto/load_balancer.pb.c",
     "src/core/surface/api_trace.c",
     "src/core/surface/byte_buffer.c",
-    "src/core/surface/byte_buffer_queue.c",
     "src/core/surface/byte_buffer_reader.c",
     "src/core/surface/call.c",
     "src/core/surface/call_details.c",
@@ -669,6 +685,7 @@ cc_library(
     "src/core/surface/server_chttp2.c",
     "src/core/surface/server_create.c",
     "src/core/surface/version.c",
+    "src/core/transport/byte_stream.c",
     "src/core/transport/chttp2/alpn.c",
     "src/core/transport/chttp2/bin_encoder.c",
     "src/core/transport/chttp2/frame_data.c",
@@ -677,13 +694,13 @@ cc_library(
     "src/core/transport/chttp2/frame_rst_stream.c",
     "src/core/transport/chttp2/frame_settings.c",
     "src/core/transport/chttp2/frame_window_update.c",
+    "src/core/transport/chttp2/hpack_encoder.c",
     "src/core/transport/chttp2/hpack_parser.c",
     "src/core/transport/chttp2/hpack_table.c",
     "src/core/transport/chttp2/huffsyms.c",
     "src/core/transport/chttp2/incoming_metadata.c",
     "src/core/transport/chttp2/parsing.c",
     "src/core/transport/chttp2/status_conversion.c",
-    "src/core/transport/chttp2/stream_encoder.c",
     "src/core/transport/chttp2/stream_lists.c",
     "src/core/transport/chttp2/stream_map.c",
     "src/core/transport/chttp2/timeout_encoding.c",
@@ -692,7 +709,8 @@ cc_library(
     "src/core/transport/chttp2_transport.c",
     "src/core/transport/connectivity_state.c",
     "src/core/transport/metadata.c",
-    "src/core/transport/stream_op.c",
+    "src/core/transport/metadata_batch.c",
+    "src/core/transport/static_metadata.c",
     "src/core/transport/transport.c",
     "src/core/transport/transport_op_string.c",
     "third_party/nanopb/pb_common.c",
@@ -752,14 +770,13 @@ cc_library(
     "src/cpp/server/dynamic_thread_pool.h",
     "src/cpp/server/fixed_size_thread_pool.h",
     "src/cpp/server/thread_pool_interface.h",
-    "src/cpp/client/secure_channel_arguments.cc",
     "src/cpp/client/secure_credentials.cc",
     "src/cpp/common/auth_property_iterator.cc",
     "src/cpp/common/secure_auth_context.cc",
+    "src/cpp/common/secure_channel_arguments.cc",
     "src/cpp/common/secure_create_auth_context.cc",
     "src/cpp/server/secure_server_credentials.cc",
     "src/cpp/client/channel.cc",
-    "src/cpp/client/channel_arguments.cc",
     "src/cpp/client/client_context.cc",
     "src/cpp/client/create_channel.cc",
     "src/cpp/client/create_channel_internal.cc",
@@ -767,6 +784,7 @@ cc_library(
     "src/cpp/client/generic_stub.cc",
     "src/cpp/client/insecure_credentials.cc",
     "src/cpp/common/call.cc",
+    "src/cpp/common/channel_arguments.cc",
     "src/cpp/common/completion_queue.cc",
     "src/cpp/common/rpc_method.cc",
     "src/cpp/proto/proto_utils.cc",
@@ -800,6 +818,7 @@ cc_library(
     "include/grpc++/impl/rpc_method.h",
     "include/grpc++/impl/rpc_service_method.h",
     "include/grpc++/impl/serialization_traits.h",
+    "include/grpc++/impl/server_builder_option.h",
     "include/grpc++/impl/service_type.h",
     "include/grpc++/impl/sync.h",
     "include/grpc++/impl/sync_cxx11.h",
@@ -851,7 +870,6 @@ cc_library(
     "src/cpp/server/thread_pool_interface.h",
     "src/cpp/common/insecure_create_auth_context.cc",
     "src/cpp/client/channel.cc",
-    "src/cpp/client/channel_arguments.cc",
     "src/cpp/client/client_context.cc",
     "src/cpp/client/create_channel.cc",
     "src/cpp/client/create_channel_internal.cc",
@@ -859,6 +877,7 @@ cc_library(
     "src/cpp/client/generic_stub.cc",
     "src/cpp/client/insecure_credentials.cc",
     "src/cpp/common/call.cc",
+    "src/cpp/common/channel_arguments.cc",
     "src/cpp/common/completion_queue.cc",
     "src/cpp/common/rpc_method.cc",
     "src/cpp/proto/proto_utils.cc",
@@ -892,6 +911,7 @@ cc_library(
     "include/grpc++/impl/rpc_method.h",
     "include/grpc++/impl/rpc_service_method.h",
     "include/grpc++/impl/serialization_traits.h",
+    "include/grpc++/impl/server_builder_option.h",
     "include/grpc++/impl/service_type.h",
     "include/grpc++/impl/sync.h",
     "include/grpc++/impl/sync_cxx11.h",
@@ -993,6 +1013,7 @@ objc_library(
     "src/core/profiling/basic_timers.c",
     "src/core/profiling/stap_timers.c",
     "src/core/support/alloc.c",
+    "src/core/support/avl.c",
     "src/core/support/cmdline.c",
     "src/core/support/cpu_iphone.c",
     "src/core/support/cpu_linux.c",
@@ -1037,6 +1058,7 @@ objc_library(
     "include/grpc/support/atm_gcc_atomic.h",
     "include/grpc/support/atm_gcc_sync.h",
     "include/grpc/support/atm_win32.h",
+    "include/grpc/support/avl.h",
     "include/grpc/support/cmdline.h",
     "include/grpc/support/cpu.h",
     "include/grpc/support/histogram.h",
@@ -1114,8 +1136,11 @@ objc_library(
     "src/core/channel/http_client_filter.c",
     "src/core/channel/http_server_filter.c",
     "src/core/channel/noop_filter.c",
+    "src/core/channel/subchannel_call_holder.c",
     "src/core/client_config/client_config.c",
     "src/core/client_config/connector.c",
+    "src/core/client_config/default_initial_connect_string.c",
+    "src/core/client_config/initial_connect_string.c",
     "src/core/client_config/lb_policies/load_balancer_api.c",
     "src/core/client_config/lb_policies/pick_first.c",
     "src/core/client_config/lb_policies/round_robin.c",
@@ -1185,7 +1210,6 @@ objc_library(
     "src/core/proto/load_balancer.pb.c",
     "src/core/surface/api_trace.c",
     "src/core/surface/byte_buffer.c",
-    "src/core/surface/byte_buffer_queue.c",
     "src/core/surface/byte_buffer_reader.c",
     "src/core/surface/call.c",
     "src/core/surface/call_details.c",
@@ -1202,6 +1226,7 @@ objc_library(
     "src/core/surface/server_chttp2.c",
     "src/core/surface/server_create.c",
     "src/core/surface/version.c",
+    "src/core/transport/byte_stream.c",
     "src/core/transport/chttp2/alpn.c",
     "src/core/transport/chttp2/bin_encoder.c",
     "src/core/transport/chttp2/frame_data.c",
@@ -1210,13 +1235,13 @@ objc_library(
     "src/core/transport/chttp2/frame_rst_stream.c",
     "src/core/transport/chttp2/frame_settings.c",
     "src/core/transport/chttp2/frame_window_update.c",
+    "src/core/transport/chttp2/hpack_encoder.c",
     "src/core/transport/chttp2/hpack_parser.c",
     "src/core/transport/chttp2/hpack_table.c",
     "src/core/transport/chttp2/huffsyms.c",
     "src/core/transport/chttp2/incoming_metadata.c",
     "src/core/transport/chttp2/parsing.c",
     "src/core/transport/chttp2/status_conversion.c",
-    "src/core/transport/chttp2/stream_encoder.c",
     "src/core/transport/chttp2/stream_lists.c",
     "src/core/transport/chttp2/stream_map.c",
     "src/core/transport/chttp2/timeout_encoding.c",
@@ -1225,7 +1250,8 @@ objc_library(
     "src/core/transport/chttp2_transport.c",
     "src/core/transport/connectivity_state.c",
     "src/core/transport/metadata.c",
-    "src/core/transport/stream_op.c",
+    "src/core/transport/metadata_batch.c",
+    "src/core/transport/static_metadata.c",
     "src/core/transport/transport.c",
     "src/core/transport/transport_op_string.c",
     "third_party/nanopb/pb_common.c",
@@ -1268,8 +1294,10 @@ objc_library(
     "src/core/channel/http_client_filter.h",
     "src/core/channel/http_server_filter.h",
     "src/core/channel/noop_filter.h",
+    "src/core/channel/subchannel_call_holder.h",
     "src/core/client_config/client_config.h",
     "src/core/client_config/connector.h",
+    "src/core/client_config/initial_connect_string.h",
     "src/core/client_config/lb_policies/load_balancer_api.h",
     "src/core/client_config/lb_policies/pick_first.h",
     "src/core/client_config/lb_policies/round_robin.h",
@@ -1286,6 +1314,7 @@ objc_library(
     "src/core/client_config/subchannel_factory_decorators/add_channel_arg.h",
     "src/core/client_config/subchannel_factory_decorators/merge_channel_args.h",
     "src/core/client_config/uri_parser.h",
+    "src/core/compression/algorithm_metadata.h",
     "src/core/compression/message_compress.h",
     "src/core/debug/trace.h",
     "src/core/httpcli/format_request.h",
@@ -1336,7 +1365,6 @@ objc_library(
     "src/core/statistics/census_interface.h",
     "src/core/statistics/census_rpc_stats.h",
     "src/core/surface/api_trace.h",
-    "src/core/surface/byte_buffer_queue.h",
     "src/core/surface/call.h",
     "src/core/surface/call_test_only.h",
     "src/core/surface/channel.h",
@@ -1345,6 +1373,7 @@ objc_library(
     "src/core/surface/init.h",
     "src/core/surface/server.h",
     "src/core/surface/surface_trace.h",
+    "src/core/transport/byte_stream.h",
     "src/core/transport/chttp2/alpn.h",
     "src/core/transport/chttp2/bin_encoder.h",
     "src/core/transport/chttp2/frame.h",
@@ -1354,6 +1383,7 @@ objc_library(
     "src/core/transport/chttp2/frame_rst_stream.h",
     "src/core/transport/chttp2/frame_settings.h",
     "src/core/transport/chttp2/frame_window_update.h",
+    "src/core/transport/chttp2/hpack_encoder.h",
     "src/core/transport/chttp2/hpack_parser.h",
     "src/core/transport/chttp2/hpack_table.h",
     "src/core/transport/chttp2/http2_errors.h",
@@ -1361,14 +1391,14 @@ objc_library(
     "src/core/transport/chttp2/incoming_metadata.h",
     "src/core/transport/chttp2/internal.h",
     "src/core/transport/chttp2/status_conversion.h",
-    "src/core/transport/chttp2/stream_encoder.h",
     "src/core/transport/chttp2/stream_map.h",
     "src/core/transport/chttp2/timeout_encoding.h",
     "src/core/transport/chttp2/varint.h",
     "src/core/transport/chttp2_transport.h",
     "src/core/transport/connectivity_state.h",
     "src/core/transport/metadata.h",
-    "src/core/transport/stream_op.h",
+    "src/core/transport/metadata_batch.h",
+    "src/core/transport/static_metadata.h",
     "src/core/transport/transport.h",
     "src/core/transport/transport_impl.h",
     "third_party/nanopb/pb.h",

binding.gyp

@@ -97,6 +97,7 @@
         'src/core/profiling/basic_timers.c',
         'src/core/profiling/stap_timers.c',
         'src/core/support/alloc.c',
+        'src/core/support/avl.c',
         'src/core/support/cmdline.c',
         'src/core/support/cpu_iphone.c',
         'src/core/support/cpu_linux.c',
@@ -183,8 +184,11 @@
         'src/core/channel/http_client_filter.c',
         'src/core/channel/http_server_filter.c',
         'src/core/channel/noop_filter.c',
+        'src/core/channel/subchannel_call_holder.c',
         'src/core/client_config/client_config.c',
         'src/core/client_config/connector.c',
+        'src/core/client_config/default_initial_connect_string.c',
+        'src/core/client_config/initial_connect_string.c',
         'src/core/client_config/lb_policies/load_balancer_api.c',
         'src/core/client_config/lb_policies/pick_first.c',
         'src/core/client_config/lb_policies/round_robin.c',
@@ -254,7 +258,6 @@
         'src/core/proto/load_balancer.pb.c',
         'src/core/surface/api_trace.c',
         'src/core/surface/byte_buffer.c',
-        'src/core/surface/byte_buffer_queue.c',
         'src/core/surface/byte_buffer_reader.c',
         'src/core/surface/call.c',
         'src/core/surface/call_details.c',
@@ -271,6 +274,7 @@
         'src/core/surface/server_chttp2.c',
         'src/core/surface/server_create.c',
         'src/core/surface/version.c',
+        'src/core/transport/byte_stream.c',
         'src/core/transport/chttp2/alpn.c',
         'src/core/transport/chttp2/bin_encoder.c',
         'src/core/transport/chttp2/frame_data.c',
@@ -279,13 +283,13 @@
         'src/core/transport/chttp2/frame_rst_stream.c',
         'src/core/transport/chttp2/frame_settings.c',
         'src/core/transport/chttp2/frame_window_update.c',
+        'src/core/transport/chttp2/hpack_encoder.c',
         'src/core/transport/chttp2/hpack_parser.c',
         'src/core/transport/chttp2/hpack_table.c',
         'src/core/transport/chttp2/huffsyms.c',
         'src/core/transport/chttp2/incoming_metadata.c',
         'src/core/transport/chttp2/parsing.c',
         'src/core/transport/chttp2/status_conversion.c',
-        'src/core/transport/chttp2/stream_encoder.c',
         'src/core/transport/chttp2/stream_lists.c',
         'src/core/transport/chttp2/stream_map.c',
         'src/core/transport/chttp2/timeout_encoding.c',
@@ -294,7 +298,8 @@
         'src/core/transport/chttp2_transport.c',
         'src/core/transport/connectivity_state.c',
         'src/core/transport/metadata.c',
-        'src/core/transport/stream_op.c',
+        'src/core/transport/metadata_batch.c',
+        'src/core/transport/static_metadata.c',
         'src/core/transport/transport.c',
         'src/core/transport/transport_op_string.c',
         'third_party/nanopb/pb_common.c',
@@ -351,11 +356,12 @@
         "src/node/ext/node_grpc.cc",
         "src/node/ext/server.cc",
         "src/node/ext/server_credentials.cc",
-        "src/node/ext/timeval.cc"
+        "src/node/ext/timeval.cc",
       ],
       "dependencies": [
-        "grpc"
+        "grpc",
+        "gpr",
       ]
-    }
+    },
   ]
 }

build.yaml

@@ -5,7 +5,7 @@ settings:
   '#': The public version number of the library.
   version:
     major: 0
-    minor: 11
+    minor: 12
     micro: 0
     build: 0
 filegroups:
@@ -37,6 +37,7 @@ filegroups:
   - include/grpc++/impl/rpc_method.h
   - include/grpc++/impl/rpc_service_method.h
   - include/grpc++/impl/serialization_traits.h
+  - include/grpc++/impl/server_builder_option.h
   - include/grpc++/impl/service_type.h
   - include/grpc++/impl/sync.h
   - include/grpc++/impl/sync_cxx11.h
@@ -72,7 +73,6 @@ filegroups:
   - src/cpp/server/thread_pool_interface.h
   src:
   - src/cpp/client/channel.cc
-  - src/cpp/client/channel_arguments.cc
   - src/cpp/client/client_context.cc
   - src/cpp/client/create_channel.cc
   - src/cpp/client/create_channel_internal.cc
@@ -80,6 +80,7 @@ filegroups:
   - src/cpp/client/generic_stub.cc
   - src/cpp/client/insecure_credentials.cc
   - src/cpp/common/call.cc
+  - src/cpp/common/channel_arguments.cc
   - src/cpp/common/completion_queue.cc
   - src/cpp/common/rpc_method.cc
   - src/cpp/proto/proto_utils.cc
@@ -116,8 +117,10 @@ filegroups:
   - src/core/channel/http_client_filter.h
   - src/core/channel/http_server_filter.h
   - src/core/channel/noop_filter.h
+  - src/core/channel/subchannel_call_holder.h
   - src/core/client_config/client_config.h
   - src/core/client_config/connector.h
+  - src/core/client_config/initial_connect_string.h
   - src/core/client_config/lb_policies/load_balancer_api.h
   - src/core/client_config/lb_policies/pick_first.h
   - src/core/client_config/lb_policies/round_robin.h
@@ -134,6 +137,7 @@ filegroups:
   - src/core/client_config/subchannel_factory_decorators/add_channel_arg.h
   - src/core/client_config/subchannel_factory_decorators/merge_channel_args.h
   - src/core/client_config/uri_parser.h
+  - src/core/compression/algorithm_metadata.h
   - src/core/compression/message_compress.h
   - src/core/debug/trace.h
   - src/core/httpcli/format_request.h
@@ -184,7 +188,6 @@ filegroups:
   - src/core/statistics/census_interface.h
   - src/core/statistics/census_rpc_stats.h
   - src/core/surface/api_trace.h
-  - src/core/surface/byte_buffer_queue.h
   - src/core/surface/call.h
   - src/core/surface/call_test_only.h
   - src/core/surface/channel.h
@@ -193,6 +196,7 @@ filegroups:
   - src/core/surface/init.h
   - src/core/surface/server.h
   - src/core/surface/surface_trace.h
+  - src/core/transport/byte_stream.h
   - src/core/transport/chttp2/alpn.h
   - src/core/transport/chttp2/bin_encoder.h
   - src/core/transport/chttp2/frame.h
@@ -202,6 +206,7 @@ filegroups:
   - src/core/transport/chttp2/frame_rst_stream.h
   - src/core/transport/chttp2/frame_settings.h
   - src/core/transport/chttp2/frame_window_update.h
+  - src/core/transport/chttp2/hpack_encoder.h
   - src/core/transport/chttp2/hpack_parser.h
   - src/core/transport/chttp2/hpack_table.h
   - src/core/transport/chttp2/http2_errors.h
@@ -209,14 +214,14 @@ filegroups:
   - src/core/transport/chttp2/incoming_metadata.h
   - src/core/transport/chttp2/internal.h
   - src/core/transport/chttp2/status_conversion.h
-  - src/core/transport/chttp2/stream_encoder.h
   - src/core/transport/chttp2/stream_map.h
   - src/core/transport/chttp2/timeout_encoding.h
   - src/core/transport/chttp2/varint.h
   - src/core/transport/chttp2_transport.h
   - src/core/transport/connectivity_state.h
   - src/core/transport/metadata.h
-  - src/core/transport/stream_op.h
+  - src/core/transport/metadata_batch.h
+  - src/core/transport/static_metadata.h
   - src/core/transport/transport.h
   - src/core/transport/transport_impl.h
   - third_party/nanopb/pb.h
@@ -235,8 +240,11 @@ filegroups:
   - src/core/channel/http_client_filter.c
   - src/core/channel/http_server_filter.c
   - src/core/channel/noop_filter.c
+  - src/core/channel/subchannel_call_holder.c
   - src/core/client_config/client_config.c
   - src/core/client_config/connector.c
+  - src/core/client_config/default_initial_connect_string.c
+  - src/core/client_config/initial_connect_string.c
   - src/core/client_config/lb_policies/load_balancer_api.c
   - src/core/client_config/lb_policies/pick_first.c
   - src/core/client_config/lb_policies/round_robin.c
@@ -306,7 +314,6 @@ filegroups:
   - src/core/proto/load_balancer.pb.c
   - src/core/surface/api_trace.c
   - src/core/surface/byte_buffer.c
-  - src/core/surface/byte_buffer_queue.c
   - src/core/surface/byte_buffer_reader.c
   - src/core/surface/call.c
   - src/core/surface/call_details.c
@@ -323,6 +330,7 @@ filegroups:
   - src/core/surface/server_chttp2.c
   - src/core/surface/server_create.c
   - src/core/surface/version.c
+  - src/core/transport/byte_stream.c
   - src/core/transport/chttp2/alpn.c
   - src/core/transport/chttp2/bin_encoder.c
   - src/core/transport/chttp2/frame_data.c
@@ -331,13 +339,13 @@ filegroups:
   - src/core/transport/chttp2/frame_rst_stream.c
   - src/core/transport/chttp2/frame_settings.c
   - src/core/transport/chttp2/frame_window_update.c
+  - src/core/transport/chttp2/hpack_encoder.c
   - src/core/transport/chttp2/hpack_parser.c
   - src/core/transport/chttp2/hpack_table.c
   - src/core/transport/chttp2/huffsyms.c
   - src/core/transport/chttp2/incoming_metadata.c
   - src/core/transport/chttp2/parsing.c
   - src/core/transport/chttp2/status_conversion.c
-  - src/core/transport/chttp2/stream_encoder.c
   - src/core/transport/chttp2/stream_lists.c
   - src/core/transport/chttp2/stream_map.c
   - src/core/transport/chttp2/timeout_encoding.c
@@ -346,7 +354,8 @@ filegroups:
   - src/core/transport/chttp2_transport.c
   - src/core/transport/connectivity_state.c
   - src/core/transport/metadata.c
-  - src/core/transport/stream_op.c
+  - src/core/transport/metadata_batch.c
+  - src/core/transport/static_metadata.c
   - src/core/transport/transport.c
   - src/core/transport/transport_op_string.c
   - third_party/nanopb/pb_common.c
@@ -357,7 +366,6 @@ filegroups:
   - test/core/end2end/cq_verifier.h
   - test/core/end2end/fixtures/proxy.h
   - test/core/iomgr/endpoint_tests.h
-  - test/core/security/oauth2_utils.h
   - test/core/util/grpc_profiler.h
   - test/core/util/parse_hexstring.h
   - test/core/util/port.h
@@ -366,7 +374,6 @@ filegroups:
   - test/core/end2end/cq_verifier.c
   - test/core/end2end/fixtures/proxy.c
   - test/core/iomgr/endpoint_tests.c
-  - test/core/security/oauth2_utils.c
   - test/core/util/grpc_profiler.c
   - test/core/util/parse_hexstring.c
   - test/core/util/port_posix.c
@@ -382,6 +389,7 @@ libs:
   - include/grpc/support/atm_gcc_atomic.h
   - include/grpc/support/atm_gcc_sync.h
   - include/grpc/support/atm_win32.h
+  - include/grpc/support/avl.h
   - include/grpc/support/cmdline.h
   - include/grpc/support/cpu.h
   - include/grpc/support/histogram.h
@@ -419,6 +427,7 @@ libs:
   - src/core/profiling/basic_timers.c
   - src/core/profiling/stap_timers.c
   - src/core/support/alloc.c
+  - src/core/support/avl.c
   - src/core/support/cmdline.c
   - src/core/support/cpu_iphone.c
   - src/core/support/cpu_linux.c
@@ -527,10 +536,12 @@ libs:
   language: c
   headers:
   - test/core/end2end/data/ssl_test_data.h
+  - test/core/security/oauth2_utils.h
   src:
   - test/core/end2end/data/server1_cert.c
   - test/core/end2end/data/server1_key.c
   - test/core/end2end/data/test_root_cert.c
+  - test/core/security/oauth2_utils.c
   deps:
   - gpr
   - gpr_test_util
@@ -544,7 +555,7 @@ libs:
   deps:
   - gpr
   - gpr_test_util
-  - grpc
+  - grpc_unsecure
   filegroups:
   - grpc_test_util_base
   secure: false
@@ -588,6 +599,19 @@ libs:
   src:
   - test/core/util/reconnect_server.c
   deps:
+  - test_tcp_server
+  - grpc_test_util
+  - grpc
+  - gpr_test_util
+  - gpr
+- name: test_tcp_server
+  build: private
+  language: c
+  headers:
+  - test/core/util/test_tcp_server.h
+  src:
+  - test/core/util/test_tcp_server.c
+  deps:
   - grpc_test_util
   - grpc
   - gpr_test_util
@@ -600,10 +624,10 @@ libs:
   - src/cpp/common/secure_auth_context.h
   - src/cpp/server/secure_server_credentials.h
   src:
-  - src/cpp/client/secure_channel_arguments.cc
   - src/cpp/client/secure_credentials.cc
   - src/cpp/common/auth_property_iterator.cc
   - src/cpp/common/secure_auth_context.cc
+  - src/cpp/common/secure_channel_arguments.cc
   - src/cpp/common/secure_create_auth_context.cc
   - src/cpp/server/secure_server_credentials.cc
   deps:
@@ -762,7 +786,11 @@ libs:
   - test/cpp/qps/timer.h
   - test/cpp/util/benchmark_config.h
   src:
-  - test/proto/qpstest.proto
+  - test/proto/messages.proto
+  - test/proto/benchmarks/control.proto
+  - test/proto/benchmarks/payloads.proto
+  - test/proto/benchmarks/services.proto
+  - test/proto/benchmarks/stats.proto
   - test/cpp/qps/perf_db.proto
   - test/cpp/qps/client_async.cc
   - test/cpp/qps/client_sync.cc
@@ -818,21 +846,21 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
-- name: chttp2_status_conversion_test
+- name: chttp2_hpack_encoder_test
   build: test
   language: c
   src:
-  - test/core/transport/chttp2/status_conversion_test.c
+  - test/core/transport/chttp2/hpack_encoder_test.c
   deps:
   - grpc_test_util
   - grpc
   - gpr_test_util
   - gpr
-- name: chttp2_stream_encoder_test
+- name: chttp2_status_conversion_test
   build: test
   language: c
   src:
-  - test/core/transport/chttp2/stream_encoder_test.c
+  - test/core/transport/chttp2/status_conversion_test.c
   deps:
   - grpc_test_util
   - grpc
@@ -974,6 +1002,14 @@ targets:
   src:
   - tools/codegen/core/gen_legal_metadata_characters.c
   deps: []
+- name: gpr_avl_test
+  build: test
+  language: c
+  src:
+  - test/core/support/avl_test.c
+  deps:
+  - gpr_test_util
+  - gpr
 - name: gpr_cmdline_test
   build: test
   language: c
@@ -1236,16 +1272,6 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
-- name: grpc_stream_op_test
-  build: test
-  language: c
-  src:
-  - test/core/transport/stream_op_test.c
-  deps:
-  - grpc_test_util
-  - grpc
-  - gpr_test_util
-  - gpr
 - name: grpc_verify_jwt
   build: tool
   language: c
@@ -1441,6 +1467,17 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
+- name: set_initial_connect_string_test
+  build: test
+  language: c
+  src:
+  - test/core/client_config/set_initial_connect_string_test.c
+  deps:
+  - test_tcp_server
+  - grpc_test_util
+  - grpc
+  - gpr_test_util
+  - gpr
 - name: sockaddr_utils_test
   build: test
   language: c
@@ -1667,7 +1704,7 @@ targets:
   build: test
   language: c++
   src:
-  - test/cpp/client/channel_arguments_test.cc
+  - test/cpp/common/channel_arguments_test.cc
   deps:
   - grpc++
   - grpc
@@ -1912,6 +1949,20 @@ targets:
   - mac
   - linux
   - posix
+- name: metrics_client
+  build: test
+  run: false
+  language: c++
+  headers:
+  - test/cpp/util/metrics_server.h
+  src:
+  - test/proto/metrics.proto
+  - test/cpp/interop/metrics_client.cc
+  deps:
+  - grpc++
+  - grpc
+  - gpr
+  - grpc++_test_config
 - name: mock_test
   build: test
   language: c++
@@ -2040,6 +2091,7 @@ targets:
   - test/cpp/interop/reconnect_interop_server.cc
   deps:
   - reconnect_server
+  - test_tcp_server
   - grpc++_test_util
   - grpc_test_util
   - grpc++
@@ -2059,6 +2111,23 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
+- name: secure_sync_unary_ping_pong_test
+  build: test
+  language: c++
+  src:
+  - test/cpp/qps/secure_sync_unary_ping_pong_test.cc
+  deps:
+  - qps
+  - grpc++_test_util
+  - grpc_test_util
+  - grpc++
+  - grpc
+  - gpr_test_util
+  - gpr
+  platforms:
+  - mac
+  - linux
+  - posix
 - name: server_crash_test
   build: test
   language: c++
@@ -2135,13 +2204,16 @@ targets:
   - test/cpp/interop/client_helper.h
   - test/cpp/interop/interop_client.h
   - test/cpp/interop/stress_interop_client.h
+  - test/cpp/util/metrics_server.h
   src:
   - test/proto/empty.proto
   - test/proto/messages.proto
+  - test/proto/metrics.proto
   - test/proto/test.proto
   - test/cpp/interop/interop_client.cc
   - test/cpp/interop/stress_interop_client.cc
   - test/cpp/interop/stress_test.cc
+  - test/cpp/util/metrics_server.cc
   deps:
   - grpc++_test_util
   - grpc_test_util
@@ -2219,11 +2291,11 @@ vspackages:
   name: grpc.dependencies.zlib
   props: false
   redist: true
-  version: 1.2.8.9
+  version: 1.2.8.10
 - name: grpc.dependencies.openssl
   props: true
   redist: true
-  version: 1.0.2.3
+  version: 1.0.204.1
 - name: gflags
   props: false
   redist: false
@@ -2232,3 +2304,36 @@ vspackages:
   props: false
   redist: false
   version: 1.7.0.1
+node_modules:
+- deps:
+  - grpc
+  - gpr
+  headers:
+  - src/node/ext/byte_buffer.h
+  - src/node/ext/call.h
+  - src/node/ext/call_credentials.h
+  - src/node/ext/channel.h
+  - src/node/ext/channel_credentials.h
+  - src/node/ext/completion_queue_async_worker.h
+  - src/node/ext/server.h
+  - src/node/ext/server_credentials.h
+  - src/node/ext/timeval.h
+  js:
+  - src/node/index.js
+  - src/node/src/client.js
+  - src/node/src/common.js
+  - src/node/src/credentials.js
+  - src/node/src/metadata.js
+  - src/node/src/server.js
+  name: grpc_node
+  src:
+  - src/node/ext/byte_buffer.cc
+  - src/node/ext/call.cc
+  - src/node/ext/call_credentials.cc
+  - src/node/ext/channel.cc
+  - src/node/ext/channel_credentials.cc
+  - src/node/ext/completion_queue_async_worker.cc
+  - src/node/ext/node_grpc.cc
+  - src/node/ext/server.cc
+  - src/node/ext/server_credentials.cc
+  - src/node/ext/timeval.cc

doc/PROTOCOL-HTTP2.md

@@ -10,58 +10,82 @@ Production rules are using <a href="http://tools.ietf.org/html/rfc5234">ABNF syn
 
 The following is the general sequence of message atoms in a GRPC request & response message stream
 
-* Request → Request-Headers *Delimited-Message EOS
-* Response → (Response-Headers *Delimited-Message Trailers) / Trailers-Only
+* Request → Request-Headers \*Length-Prefixed-Message EOS
+* Response → (Response-Headers \*Length-Prefixed-Message Trailers) / Trailers-Only
 
 
 ### Requests
 
-* Request → Request-Headers *Delimited-Message EOS
+* Request → Request-Headers \*Length-Prefixed-Message EOS
 
 Request-Headers are delivered as HTTP2 headers in HEADERS + CONTINUATION frames.
 
-* **Request-Headers** → Call-Definition *Custom-Metadata
-* **Call-Definition** → Method Scheme Path TE [Authority] [Timeout] [Content-Type] [Message-Type] [Message-Encoding] [Message-Accept-Encoding] [User-Agent]
-* **Method** →  “:method POST”
-* **Scheme** → “:scheme ”  (“http” / “https”)
-* **Path** → “:path”  {_path identifying method within exposed API_}
-* **Authority** → “:authority” {_virtual host name of authority_}
-* **TE** → “te” “trailers”  # Used to detect incompatible proxies
-* **Timeout** → “grpc-timeout” TimeoutValue TimeoutUnit
+* **Request-Headers** → Call-Definition \*Custom-Metadata
+* **Call-Definition** → Method Scheme Path TE [Authority] [Timeout] Content-Type [Message-Type] [Message-Encoding] [Message-Accept-Encoding] [User-Agent]
+* **Method** →  ":method POST"
+* **Scheme** → ":scheme "  ("http" / "https")
+* **Path** → ":path"  {_path identifying method within exposed API_}
+* **Authority** → ":authority" {_virtual host name of authority_}
+* **TE** → "te" "trailers"  # Used to detect incompatible proxies
+* **Timeout** → "grpc-timeout" TimeoutValue TimeoutUnit
 * **TimeoutValue** → {_positive integer as ASCII string of at most 8 digits_}
 * **TimeoutUnit** → Hour / Minute / Second / Millisecond / Microsecond / Nanosecond
-* **Hour** → “H”
-* **Minute** → “M”
-* **Second** → “S”
-* **Millisecond** → “m”
-* **Microsecond** → “u”
-* **Nanosecond** → “n”
-* **Content-Type** → “content-type” “application/grpc” [(“+proto” / “+json” / {_custom_})]
-* **Content-Coding** → “gzip” / “deflate” / “snappy” / {_custom_}
-* **Message-Encoding** → “grpc-encoding” Content-Coding
-* **Message-Accept-Encoding** → “grpc-accept-encoding” Content-Coding *("," Content-Coding)
-* **User-Agent** → “user-agent” {_structured user-agent string_}
-* **Message-Type** → “grpc-message-type” {_type name for message schema_}
+* **Hour** → "H"
+* **Minute** → "M"
+* **Second** → "S"
+* **Millisecond** → "m"
+* **Microsecond** → "u"
+* **Nanosecond** → "n"
+* **Content-Type** → "content-type" "application/grpc" [("+proto" / "+json" / {_custom_})]
+* **Content-Coding** → "identity" / "gzip" / "deflate" / "snappy" / {_custom_}
+* **Message-Encoding** → "grpc-encoding" Content-Coding
+* **Message-Accept-Encoding** → "grpc-accept-encoding" Content-Coding \*("," Content-Coding)
+* **User-Agent** → "user-agent" {_structured user-agent string_}
+* **Message-Type** → "grpc-message-type" {_type name for message schema_}
 * **Custom-Metadata** → Binary-Header / ASCII-Header
-* **Binary-Header** → {Header-Name “-bin” } {_base64 encoded value_}
-* **ASCII-Header** → Header-Name {_value_}
-* **Header-Name** → 1*( %x30-39 / %x61-7A / “_” / “-”) ; 0-9 a-z 
+* **Binary-Header** → {Header-Name "-bin" } {_base64 encoded value_}
+* **ASCII-Header** → Header-Name ASCII-Value
+* **Header-Name** → 1\*( %x30-39 / %x61-7A / "\_" / "-") ; 0-9 a-z \_ -
+* **ASCII-Value** → 1\*( %x20-%x7E ) ; space and printable ASCII
 
 
-HTTP2 requires that reserved headers, ones starting with “:” appear before all other headers. Additionally implementations should send **Timeout** immediately after the reserved headers and they should send the **Call-Definition** headers before sending **Custom-Metadata**.
+HTTP2 requires that reserved headers, ones starting with ":" appear before all other headers. Additionally implementations should send **Timeout** immediately after the reserved headers and they should send the **Call-Definition** headers before sending **Custom-Metadata**.
 
 If **Timeout** is omitted a server should assume an infinite timeout. Client implementations are free to send a default minimum timeout based on their deployment requirements.
 
-**Custom-Metadata** is an arbitrary set of key-value pairs defined by the application layer. Aside from transport limits on the total length of HTTP2 HEADERS the only other constraint is that header names starting with “grpc-” are reserved for future use.
+**Custom-Metadata** is an arbitrary set of key-value pairs defined by the application layer. Header names starting with "grpc-" but not listed here are reserved for future GRPC use and should not be used by applications as **Custom-Metadata**.
 
-Note that HTTP2 does not allow arbitrary octet sequences for header values so binary header values must be encoded using Base64 as per https://tools.ietf.org/html/rfc4648#section-4. Implementations MUST accept padded and un-padded values and should emit un-padded values. Applications define binary headers by having their names end with “-bin”. Runtime libraries use this suffix to detect binary headers and properly apply base64 encoding & decoding as headers are sent and received.
+Note that HTTP2 does not allow arbitrary octet sequences for header values so binary header values must be encoded using Base64 as per https://tools.ietf.org/html/rfc4648#section-4. Implementations MUST accept padded and un-padded values and should emit un-padded values. Applications define binary headers by having their names end with "-bin". Runtime libraries use this suffix to detect binary headers and properly apply base64 encoding & decoding as headers are sent and received.
 
-The repeated sequence of **Delimited-Message** items is delivered in DATA frames
+**Custom-Metadata** header order is not guaranteed to be preserved except for
+values with duplicate header names. Duplicate header names may have their values
+joined with "," as the delimiter and be considered semantically equivalent.
+Implementations must split **Binary-Header**s on "," before decoding the
+Base64-encoded values.
 
-* **Delimited-Message** → Compressed-Flag Message-Length Message
+**ASCII-Value** should not have leading or trailing whitespace. If it contains
+leading or trailing whitespace, it may be stripped. The **ASCII-Value**
+character range defined is more strict than HTTP. Implementations must not error
+due to receiving an invalid **ASCII-Value** that's a valid **field-value** in
+HTTP, but the precise behavior is not strictly defined: they may throw the value
+away or accept the value. If accepted, care must be taken to make sure that the
+application is permitted to echo the value back as metadata. For example, if the
+metadata is provided to the application as a list in a request, the application
+should not trigger an error by providing that same list as the metadata in the
+response.
+
+Servers may limit the size of **Request-Headers**, with a default of 8 KiB
+suggested.  Implementations are encouraged to compute total header size like
+HTTP/2's `SETTINGS_MAX_HEADER_LIST_SIZE`: the sum of all header fields, for each
+field the sum of the uncompressed field name and value lengths plus 32, with
+binary values' lengths being post-Base64.
+
+The repeated sequence of **Length-Prefixed-Message** items is delivered in DATA frames
+
+* **Length-Prefixed-Message** → Compressed-Flag Message-Length Message
 * **Compressed-Flag** → 0 / 1   # encoded as 1 byte unsigned integer
 * **Message-Length** → {_length of Message_}  # encoded as 4 byte unsigned integer
-* **Message** → *{binary octet}
+* **Message** → \*{binary octet}
 
 A **Compressed-Flag** value of 1 indicates that the binary octet sequence of **Message** is compressed using the mechanism declared by the **Message-Encoding** header. A value of 0 indicates that no encoding of **Message** bytes has occurred. Compression contexts are NOT maintained over message boundaries, implementations must create a new context for each message in the stream. If the **Message-Encoding** header is omitted then the **Compressed-Flag** must be 0.
 
@@ -69,13 +93,13 @@ For requests, **EOS** (end-of-stream) is indicated by the presence of the END_ST
 
 ###Responses
 
-* **Response** → (Response-Headers *Delimited-Message Trailers) / Trailers-Only
-* **Response-Headers** → HTTP-Status [Message-Encoding] [Message-Accept-Encoding] Content-Type *Custom-Metadata
+* **Response** → (Response-Headers \*Length-Prefixed-Message Trailers) / Trailers-Only
+* **Response-Headers** → HTTP-Status [Message-Encoding] [Message-Accept-Encoding] Content-Type \*Custom-Metadata
 * **Trailers-Only** → HTTP-Status Content-Type Trailers
-* **Trailers** → Status [Status-Message] *Custom-Metadata
-* **HTTP-Status** → “:status 200”
-* **Status** → “grpc-status” <status-code-as-ASCII-string>
-* **Status-Message** → “grpc-message” <descriptive text for status as ASCII string>
+* **Trailers** → Status [Status-Message] \*Custom-Metadata
+* **HTTP-Status** → ":status 200"
+* **Status** → "grpc-status" <status-code-as-ASCII-string>
+* **Status-Message** → "grpc-message" <descriptive text for status as ASCII string>
 
 **Response-Headers** & **Trailers-Only** are each delivered in a single HTTP2 HEADERS frame block. Most responses are expected to have both headers and trailers but **Trailers-Only** is permitted for calls that produce an immediate error. Status must be sent in **Trailers** even if the status code is OK.
 
@@ -83,6 +107,9 @@ For responses end-of-stream is indicated by the presence of the END_STREAM flag
 
 Implementations should expect broken deployments to send non-200 HTTP status codes in responses as well as a variety of non-GRPC content-types and to omit **Status** & **Status-Message**. Implementations must synthesize a **Status** & **Status-Message** to propagate to the application layer when this occurs.
 
+Clients may limit the size of **Response-Headers**, **Trailers**, and
+**Trailers-Only**, with a default of 8 KiB each suggested.
+
 ####Example
 
 Sample unary-call showing HTTP2 framing sequence
@@ -101,7 +128,7 @@ grpc-encoding = gzip
 authorization = Bearer y235.wef315yfh138vh31hv93hv8h3v
 
 DATA (flags = END_STREAM)
-<Delimited Message>
+<Length-Prefixed Message>
 ```
 **Response**
 ```
@@ -110,7 +137,7 @@ HEADERS (flags = END_HEADERS)
 grpc-encoding = gzip
 
 DATA
-<Delimited Message>
+<Length-Prefixed Message>
 
 HEADERS (flags = END_STREAM, END_HEADERS)
 grpc-status = 0 # OK
@@ -120,7 +147,7 @@ trace-proto-bin = jher831yy13JHy3hc
 
 While the protocol does not require a user-agent to function it is recommended that clients provide a structured user-agent string that provides a basic description of the calling library, version & platform to facilitate issue diagnosis in heterogeneous environments. The following structure is recommended to library developers
 ```
-User-Agent → “grpc-” Language ?(“-” Variant) “/” Version ?( “ (“  *(AdditionalProperty “;”) “)” )
+User-Agent → "grpc-" Language ?("-" Variant) "/" Version ?( " ("  *(AdditionalProperty ";") ")" )
 ```
 E.g.
 
@@ -136,7 +163,7 @@ grpc-java-android/0.9.1 (gingerbread/1.2.4; nexus5; tmobile)
 All GRPC calls need to specify an internal ID. We will use HTTP2 stream-ids as call identifiers in this scheme. NOTE: These id’s are contextual to an open HTTP2 session and will not be unique within a given process that is handling more than one HTTP2 session nor can they be used as GUIDs.
 
 #####Data Frames
-DATA frame boundaries have no relation to **Delimited-Message** boundaries and implementations should make no assumptions about their alignment.
+DATA frame boundaries have no relation to **Length-Prefixed-Message** boundaries and implementations should make no assumptions about their alignment.
 
 #####Errors
 

doc/grpc-auth-support.md

@@ -1,289 +0,0 @@
-#gRPC Authentication support
-
-gRPC is designed to plug-in a number of authentication mechanisms. This document
-provides a quick overview of the various auth mechanisms supported, discusses
-the API with some examples, and concludes with a discussion of extensibility.
-More documentation and examples are coming soon!
-
-## Supported auth mechanisms
-
-###SSL/TLS
-gRPC has SSL/TLS integration and promotes the use of SSL/TLS to authenticate the
-server, and encrypt all the data exchanged between the client and the server.
-Optional mechanisms are available for clients to provide certificates to
-accomplish mutual authentication.
-
-###OAuth 2.0
-gRPC provides a generic mechanism (described below) to attach metadata to
-requests and responses. This mechanism can be used to attach OAuth 2.0 Access
-Tokens to RPCs being made at a client. Additional support for acquiring Access
-Tokens while accessing Google APIs through gRPC is provided for certain auth
-flows, demonstrated through code examples below.
-
-## API
-To reduce complexity and minimize API clutter, gRPC works with a unified concept
-of a Credentials object. Users construct gRPC credentials using corresponding
-bootstrap credentials (e.g., SSL client certs or Service Account Keys), and use
-the credentials while creating a gRPC channel to any server. Depending on the
-type of credential supplied, the channel uses the credentials during the initial
-SSL/TLS handshake with the server, or uses  the credential to generate and
-attach Access Tokens to each request being made on the channel.
-
-###SSL/TLS for server authentication and encryption
-This is the simplest authentication scenario, where a client just wants to
-authenticate the server and encrypt all data.
-
-```cpp
-SslCredentialsOptions ssl_opts;  // Options to override SSL params, empty by default
-// Create the credentials object by providing service account key in constructor
-std::unique_ptr<Credentials> creds = CredentialsFactory::SslCredentials(ssl_opts);
-// Create a channel using the credentials created in the previous step
-std::shared_ptr<ChannelInterface> channel = CreateChannel(server_name, creds, channel_args);
-// Create a stub on the channel
-std::unique_ptr<Greeter::Stub> stub(Greeter::NewStub(channel));
-// Make actual RPC calls on the stub.
-grpc::Status s = stub->sayHello(&context, *request, response);
-```
-
-For advanced use cases such as modifying the root CA or using client certs,
-the corresponding options can be set in the SslCredentialsOptions parameter
-passed to the factory method.
-
-
-###Authenticating with Google
-
-gRPC applications can use a simple API to create a credential that works in various deployment scenarios.
-
-```cpp
-std::unique_ptr<Credentials> creds = CredentialsFactory::GoogleDefaultCredentials();
-// Create a channel, stub and make RPC calls (same as in the previous example)
-std::shared_ptr<ChannelInterface> channel = CreateChannel(server_name, creds, channel_args);
-std::unique_ptr<Greeter::Stub> stub(Greeter::NewStub(channel));
-grpc::Status s = stub->sayHello(&context, *request, response);
-```
-
-This credential works for applications using Service Accounts as well as for
-applications running in [Google Compute Engine (GCE)](https://cloud.google.com/compute/). In the former case, the
-service account’s private keys are loaded from the file named in the environment
-variable `GOOGLE_APPLICATION_CREDENTIALS`. The
-keys are used to generate bearer tokens that are attached to each outgoing RPC
-on the corresponding channel.
-
-For applications running in GCE, a default service account and corresponding
-OAuth scopes can be configured during VM setup. At run-time, this credential
-handles communication with the authentication systems to obtain OAuth2 access
-tokens and attaches them to each outgoing RPC on the corresponding channel.
-Extending gRPC to support other authentication mechanisms
-The gRPC protocol is designed with a general mechanism for sending metadata
-associated with RPC. Clients can send metadata at the beginning of an RPC and
-servers can send back metadata at the beginning and end of the RPC. This
-provides a natural mechanism to support OAuth2 and other authentication
-mechanisms that need attach bearer tokens to individual request.
-
-In the simplest case, there is a single line of code required on the client
-to add a specific token as metadata to an RPC and a corresponding access on
-the server to retrieve this piece of metadata. The generation of the token
-on the client side and its verification at the server can be done separately.
-
-A deeper integration can be achieved by plugging in a gRPC credentials implementation for any custom authentication mechanism that needs to attach per-request tokens. gRPC internals also allow switching out SSL/TLS with other encryption mechanisms.
-
-## Examples
-
-These authentication mechanisms will be available in all gRPC's supported languages.
-The following sections demonstrate how authentication and authorization features described above appear in each language: more languages are coming soon.
-
-###SSL/TLS for server authentication and encryption (Ruby)
-```ruby
-# Base case - No encryption
-stub = Helloworld::Greeter::Stub.new('localhost:50051')
-...
-
-# With server authentication SSL/TLS
-creds = GRPC::Core::Credentials.new(load_certs)  # load_certs typically loads a CA roots file
-stub = Helloworld::Greeter::Stub.new('localhost:50051', creds: creds)
-```
-
-###SSL/TLS for server authentication and encryption (C#)
-```csharp
-// Base case - No encryption
-var channel = new Channel("localhost:50051");
-var client = new Greeter.GreeterClient(channel);
-...
-
-// With server authentication SSL/TLS
-var credentials = new SslCredentials(File.ReadAllText("ca.pem"));  // Load a CA file
-var channel = new Channel("localhost:50051", credentials);
-var client = new Greeter.GreeterClient(channel);
-```
-
-###SSL/TLS for server authentication and encryption (Objective-C)
-
-The default for Objective-C is to use SSL/TLS, as that's the most common use case when accessing
-remote APIs.
-
-```objective-c
-// Base case - With server authentication SSL/TLS
-HLWGreeter *client = [[HLWGreeter alloc] initWithHost:@"localhost:50051"];
-// Same as using @"https://localhost:50051".
-...
-
-// No encryption
-HLWGreeter *client = [[HLWGreeter alloc] initWithHost:@"http://localhost:50051"];
-// Specifying the HTTP scheme explicitly forces no encryption.
-```
-
-###SSL/TLS for server authentication and encryption (Python)
-```python
-# Base case - No encryption
-stub = early_adopter_create_GreeterService_stub('localhost', 50051)
-...
-
-# With server authentication SSL/TLS
-stub = early_adopter_create_GreeterService_stub(
-  'localhost', 50051, secure=True, root_certificates=open('ca.pem').read())
-...
-```
-n.b.: the beta API will look different
-
-###Authenticating with Google (Ruby)
-```ruby
-# Base case - No encryption/authorization
-stub = Helloworld::Greeter::Stub.new('localhost:50051')
-...
-
-# Authenticating with Google
-require 'googleauth'  # from http://www.rubydoc.info/gems/googleauth/0.1.0
-...
-creds = GRPC::Core::Credentials.new(load_certs)  # load_certs typically loads a CA roots file
-scope = 'https://www.googleapis.com/auth/grpc-testing'
-authorization = Google::Auth.get_application_default(scope)
-stub = Helloworld::Greeter::Stub.new('localhost:50051',
-                                     creds: creds,
-                                     update_metadata: authorization.updater_proc)
-```
-
-###Authenticating with Google (Node.js)
-
-```node
-// Base case - No encryption/authorization
-var stub = new helloworld.Greeter('localhost:50051');
-...
-// Authenticating with Google
-var GoogleAuth = require('google-auth-library'); // from https://www.npmjs.com/package/google-auth-library
-...
-var creds = grpc.Credentials.createSsl(load_certs); // load_certs typically loads a CA roots file
-var scope = 'https://www.googleapis.com/auth/grpc-testing';
-(new GoogleAuth()).getApplicationDefault(function(err, auth) {
-  if (auth.createScopeRequired()) {
-    auth = auth.createScoped(scope);
-  }
-  var stub = new helloworld.Greeter('localhost:50051',
-                                    {credentials: creds},
-                                    grpc.getGoogleAuthDelegate(auth));
-});
-```
-
-###Authenticating with Google (C#)
-```csharp
-// Base case - No encryption/authorization
-var channel = new Channel("localhost:50051");
-var client = new Greeter.GreeterClient(channel);
-...
-
-// Authenticating with Google
-using Grpc.Auth;  // from Grpc.Auth NuGet package
-...
-var credentials = new SslCredentials(File.ReadAllText("ca.pem"));  // Load a CA file
-var channel = new Channel("localhost:50051", credentials);
-
-string scope = "https://www.googleapis.com/auth/grpc-testing";
-var authorization = GoogleCredential.GetApplicationDefault();
-if (authorization.IsCreateScopedRequired)
-{
-    authorization = credential.CreateScoped(new[] { scope });
-}
-var client = new Greeter.GreeterClient(channel,
-        new StubConfiguration(OAuth2InterceptorFactory.Create(credential)));
-```
-
-###Authenticating with Google (PHP)
-```php
-// Base case - No encryption/authorization
-$client = new helloworld\GreeterClient(
-  new Grpc\BaseStub('localhost:50051', []));
-...
-
-// Authenticating with Google
-// the environment variable "GOOGLE_APPLICATION_CREDENTIALS" needs to be set
-$scope = "https://www.googleapis.com/auth/grpc-testing";
-$auth = Google\Auth\ApplicationDefaultCredentials::getCredentials($scope);
-$opts = [
-  'credentials' => Grpc\Credentials::createSsl(file_get_contents('ca.pem'));
-  'update_metadata' => $auth->getUpdateMetadataFunc(),
-];
-
-$client = new helloworld\GreeterClient(
-  new Grpc\BaseStub('localhost:50051', $opts));
-
-```
-
-###Authenticating with Google (Objective-C)
-
-This example uses the [Google iOS Sign-In library](https://developers.google.com/identity/sign-in/ios/),
-but it's easily extrapolated to any other OAuth2 library.
-
-```objective-c
-// Base case - No authentication
-[client sayHelloWithRequest:request handler:^(HLWHelloReply *response, NSError *error) {
-  ...
-}];
-
-...
-
-// Authenticating with Google
-
-// When signing the user in, ask her for the relevant scopes.
-GIDSignIn.sharedInstance.scopes = @[@"https://www.googleapis.com/auth/grpc-testing"];
-
-...
-
-#import <ProtoRPC/ProtoRPC.h>
-
-// Create a not-yet-started RPC. We want to set the request headers on this object before starting
-// it.
-ProtoRPC *call =
-    [client RPCToSayHelloWithRequest:request handler:^(HLWHelloReply *response, NSError *error) {
-      ...
-    }];
-
-// Set the access token to be used.
-NSString *accessToken = GIDSignIn.sharedInstance.currentUser.authentication.accessToken;
-call.requestMetadata[@"Authorization"] = [@"Bearer " stringByAppendingString:accessToken]}];
-
-// Start the RPC.
-[call start];
-```
-
-You can see a working example app, with a more detailed explanation, [here](examples/objective-c/auth_sample).
-
-### Authenticating with Google (Python)
-```python
-# Base case - No encryption
-stub = early_adopter_create_GreeterService_stub('localhost', 50051)
-...
-
-# With server authentication SSL/TLS
-import oauth2client.client
-credentials = oauth2client.GoogleCredentials.get_application_default()
-scope = 'https://www.googleapis.com/auth/grpc-testing'
-scoped_credentials = credentials.create_scoped([scope])
-access_token = scoped_credentials.get_access_token().access_token
-metadata_transformer = (
-    lambda x: [('Authorization', 'Bearer {}'.format(access_token))])
-
-stub = early_adopter_create_GreeterService_stub(
-  'localhost', 50051, secure=True, root_certificates=open('ca.pem').read(),
-  metadata_transformer=metadata_transformer)
-...
-```
-n.b.: the beta API will look different

doc/interop-test-descriptions.md

@@ -4,7 +4,7 @@ Interoperability Test Case Descriptions
 Client and server use
 [test.proto](https://github.com/grpc/grpc/blob/master/test/proto/test.proto)
 and the [gRPC over HTTP/2 v2
-protocol](doc/PROTOCOL-HTTP2.md).
+protocol](https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md).
 
 Client
 ------

examples/cpp/cpptutorial.md

@@ -245,7 +245,7 @@ To call service methods, we first need to create a *stub*.
 First we need to create a gRPC *channel* for our stub, specifying the server address and port we want to connect to without SSL:
 
 ```cpp
-grpc::CreateChannel("localhost:50051", grpc::InsecureCredentials());
+grpc::CreateChannel("localhost:50051", grpc::InsecureChannelCredentials());
 ```
 
 Now we can use the channel to create our stub using the `NewStub` method provided in the `RouteGuide` class we generated from our .proto.

examples/cpp/helloworld/README.md

@@ -94,7 +94,7 @@ $ protoc -I ../../protos/ --cpp_out=. ../../protos/helloworld.proto
   arguments as follows
 
     ```
-    auto channel = CreateChannel("localhost:50051", InsecureCredentials());
+    auto channel = CreateChannel("localhost:50051", InsecureChannelCredentials());
     ```
 
 - Create a stub. A stub implements the rpc methods of a service and in the

examples/cpp/helloworld/greeter_async_client.cc

@@ -114,9 +114,9 @@ int main(int argc, char** argv) {
   // Instantiate the client. It requires a channel, out of which the actual RPCs
   // are created. This channel models a connection to an endpoint (in this case,
   // localhost at port 50051). We indicate that the channel isn't authenticated
-  // (use of InsecureCredentials()).
-  GreeterClient greeter(
-      grpc::CreateChannel("localhost:50051", grpc::InsecureCredentials()));
+  // (use of InsecureChannelCredentials()).
+  GreeterClient greeter(grpc::CreateChannel(
+      "localhost:50051", grpc::InsecureChannelCredentials()));
   std::string user("world");
   std::string reply = greeter.SayHello(user);  // The actual RPC call!
   std::cout << "Greeter received: " << reply << std::endl;

examples/cpp/helloworld/greeter_client.cc

@@ -84,9 +84,9 @@ int main(int argc, char** argv) {
   // Instantiate the client. It requires a channel, out of which the actual RPCs
   // are created. This channel models a connection to an endpoint (in this case,
   // localhost at port 50051). We indicate that the channel isn't authenticated
-  // (use of InsecureCredentials()).
-  GreeterClient greeter(
-      grpc::CreateChannel("localhost:50051", grpc::InsecureCredentials()));
+  // (use of InsecureChannelCredentials()).
+  GreeterClient greeter(grpc::CreateChannel(
+      "localhost:50051", grpc::InsecureChannelCredentials()));
   std::string user("world");
   std::string reply = greeter.SayHello(user);
   std::cout << "Greeter received: " << reply << std::endl;

examples/cpp/route_guide/route_guide_client.cc

@@ -234,7 +234,8 @@ int main(int argc, char** argv) {
   // Expect only arg: --db_path=path/to/route_guide_db.json.
   std::string db = routeguide::GetDbFileContent(argc, argv);
   RouteGuideClient guide(
-      grpc::CreateChannel("localhost:50051", grpc::InsecureCredentials()),
+      grpc::CreateChannel("localhost:50051",
+                          grpc::InsecureChannelCredentials()),
       db);
 
   std::cout << "-------------- GetFeature --------------" << std::endl;

examples/node/README.md

@@ -4,7 +4,7 @@ gRPC in 3 minutes (Node.js)
 PREREQUISITES
 -------------
 
-- `node`: This requires Node 10.x or greater.
+- `node`: This requires Node 0.10.x or greater.
 - [homebrew][] on Mac OS X.  This simplifies the installation of the gRPC C core.
 
 INSTALL

examples/objective-c/auth_sample/AuthTestService.podspec

@@ -29,7 +29,7 @@ Pod::Spec.new do |s|
     ss.source_files = "#{dir}/*.pbrpc.{h,m}", "#{dir}/**/*.pbrpc.{h,m}"
     ss.header_mappings_dir = dir
     ss.requires_arc = true
-    ss.dependency "gRPC", "~> 0.11"
+    ss.dependency "gRPC", "~> 0.12"
     ss.dependency "#{s.name}/Messages"
   end
 end

examples/objective-c/helloworld/HelloWorld.podspec

@@ -29,7 +29,7 @@ Pod::Spec.new do |s|
     ss.source_files = "#{dir}/*.pbrpc.{h,m}", "#{dir}/**/*.pbrpc.{h,m}"
     ss.header_mappings_dir = dir
     ss.requires_arc = true
-    ss.dependency "gRPC", "~> 0.11"
+    ss.dependency "gRPC", "~> 0.12"
     ss.dependency "#{s.name}/Messages"
   end
 end

examples/objective-c/route_guide/RouteGuide.podspec

@@ -29,7 +29,7 @@ Pod::Spec.new do |s|
     ss.source_files = "#{dir}/*.pbrpc.{h,m}", "#{dir}/**/*.pbrpc.{h,m}"
     ss.header_mappings_dir = dir
     ss.requires_arc = true
-    ss.dependency "gRPC", "~> 0.11"
+    ss.dependency "gRPC", "~> 0.12"
     ss.dependency "#{s.name}/Messages"
   end
 end

examples/python/helloworld/greeter_server.py

@@ -50,7 +50,7 @@ def serve():
     while True:
       time.sleep(_ONE_DAY_IN_SECONDS)
   except KeyboardInterrupt:
-    server.stop()
+    server.stop(0)
 
 if __name__ == '__main__':
   serve()

gRPC.podspec

@@ -36,7 +36,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC'
-  version = '0.11.2'
+  version = '0.12.0'
   s.version  = version
   s.summary  = 'gRPC client library for iOS/OSX'
   s.homepage = 'http://www.grpc.io'
@@ -78,6 +78,7 @@ Pod::Spec.new do |s|
                       'include/grpc/support/atm_gcc_atomic.h',
                       'include/grpc/support/atm_gcc_sync.h',
                       'include/grpc/support/atm_win32.h',
+                      'include/grpc/support/avl.h',
                       'include/grpc/support/cmdline.h',
                       'include/grpc/support/cpu.h',
                       'include/grpc/support/histogram.h',
@@ -103,6 +104,7 @@ Pod::Spec.new do |s|
                       'src/core/profiling/basic_timers.c',
                       'src/core/profiling/stap_timers.c',
                       'src/core/support/alloc.c',
+                      'src/core/support/avl.c',
                       'src/core/support/cmdline.c',
                       'src/core/support/cpu_iphone.c',
                       'src/core/support/cpu_linux.c',
@@ -164,8 +166,10 @@ Pod::Spec.new do |s|
                       'src/core/channel/http_client_filter.h',
                       'src/core/channel/http_server_filter.h',
                       'src/core/channel/noop_filter.h',
+                      'src/core/channel/subchannel_call_holder.h',
                       'src/core/client_config/client_config.h',
                       'src/core/client_config/connector.h',
+                      'src/core/client_config/initial_connect_string.h',
                       'src/core/client_config/lb_policies/load_balancer_api.h',
                       'src/core/client_config/lb_policies/pick_first.h',
                       'src/core/client_config/lb_policies/round_robin.h',
@@ -182,6 +186,7 @@ Pod::Spec.new do |s|
                       'src/core/client_config/subchannel_factory_decorators/add_channel_arg.h',
                       'src/core/client_config/subchannel_factory_decorators/merge_channel_args.h',
                       'src/core/client_config/uri_parser.h',
+                      'src/core/compression/algorithm_metadata.h',
                       'src/core/compression/message_compress.h',
                       'src/core/debug/trace.h',
                       'src/core/httpcli/format_request.h',
@@ -232,7 +237,6 @@ Pod::Spec.new do |s|
                       'src/core/statistics/census_interface.h',
                       'src/core/statistics/census_rpc_stats.h',
                       'src/core/surface/api_trace.h',
-                      'src/core/surface/byte_buffer_queue.h',
                       'src/core/surface/call.h',
                       'src/core/surface/call_test_only.h',
                       'src/core/surface/channel.h',
@@ -241,6 +245,7 @@ Pod::Spec.new do |s|
                       'src/core/surface/init.h',
                       'src/core/surface/server.h',
                       'src/core/surface/surface_trace.h',
+                      'src/core/transport/byte_stream.h',
                       'src/core/transport/chttp2/alpn.h',
                       'src/core/transport/chttp2/bin_encoder.h',
                       'src/core/transport/chttp2/frame.h',
@@ -250,6 +255,7 @@ Pod::Spec.new do |s|
                       'src/core/transport/chttp2/frame_rst_stream.h',
                       'src/core/transport/chttp2/frame_settings.h',
                       'src/core/transport/chttp2/frame_window_update.h',
+                      'src/core/transport/chttp2/hpack_encoder.h',
                       'src/core/transport/chttp2/hpack_parser.h',
                       'src/core/transport/chttp2/hpack_table.h',
                       'src/core/transport/chttp2/http2_errors.h',
@@ -257,14 +263,14 @@ Pod::Spec.new do |s|
                       'src/core/transport/chttp2/incoming_metadata.h',
                       'src/core/transport/chttp2/internal.h',
                       'src/core/transport/chttp2/status_conversion.h',
-                      'src/core/transport/chttp2/stream_encoder.h',
                       'src/core/transport/chttp2/stream_map.h',
                       'src/core/transport/chttp2/timeout_encoding.h',
                       'src/core/transport/chttp2/varint.h',
                       'src/core/transport/chttp2_transport.h',
                       'src/core/transport/connectivity_state.h',
                       'src/core/transport/metadata.h',
-                      'src/core/transport/stream_op.h',
+                      'src/core/transport/metadata_batch.h',
+                      'src/core/transport/static_metadata.h',
                       'src/core/transport/transport.h',
                       'src/core/transport/transport_impl.h',
                       'third_party/nanopb/pb.h',
@@ -313,8 +319,11 @@ Pod::Spec.new do |s|
                       'src/core/channel/http_client_filter.c',
                       'src/core/channel/http_server_filter.c',
                       'src/core/channel/noop_filter.c',
+                      'src/core/channel/subchannel_call_holder.c',
                       'src/core/client_config/client_config.c',
                       'src/core/client_config/connector.c',
+                      'src/core/client_config/default_initial_connect_string.c',
+                      'src/core/client_config/initial_connect_string.c',
                       'src/core/client_config/lb_policies/load_balancer_api.c',
                       'src/core/client_config/lb_policies/pick_first.c',
                       'src/core/client_config/lb_policies/round_robin.c',
@@ -384,7 +393,6 @@ Pod::Spec.new do |s|
                       'src/core/proto/load_balancer.pb.c',
                       'src/core/surface/api_trace.c',
                       'src/core/surface/byte_buffer.c',
-                      'src/core/surface/byte_buffer_queue.c',
                       'src/core/surface/byte_buffer_reader.c',
                       'src/core/surface/call.c',
                       'src/core/surface/call_details.c',
@@ -401,6 +409,7 @@ Pod::Spec.new do |s|
                       'src/core/surface/server_chttp2.c',
                       'src/core/surface/server_create.c',
                       'src/core/surface/version.c',
+                      'src/core/transport/byte_stream.c',
                       'src/core/transport/chttp2/alpn.c',
                       'src/core/transport/chttp2/bin_encoder.c',
                       'src/core/transport/chttp2/frame_data.c',
@@ -409,13 +418,13 @@ Pod::Spec.new do |s|
                       'src/core/transport/chttp2/frame_rst_stream.c',
                       'src/core/transport/chttp2/frame_settings.c',
                       'src/core/transport/chttp2/frame_window_update.c',
+                      'src/core/transport/chttp2/hpack_encoder.c',
                       'src/core/transport/chttp2/hpack_parser.c',
                       'src/core/transport/chttp2/hpack_table.c',
                       'src/core/transport/chttp2/huffsyms.c',
                       'src/core/transport/chttp2/incoming_metadata.c',
                       'src/core/transport/chttp2/parsing.c',
                       'src/core/transport/chttp2/status_conversion.c',
-                      'src/core/transport/chttp2/stream_encoder.c',
                       'src/core/transport/chttp2/stream_lists.c',
                       'src/core/transport/chttp2/stream_map.c',
                       'src/core/transport/chttp2/timeout_encoding.c',
@@ -424,7 +433,8 @@ Pod::Spec.new do |s|
                       'src/core/transport/chttp2_transport.c',
                       'src/core/transport/connectivity_state.c',
                       'src/core/transport/metadata.c',
-                      'src/core/transport/stream_op.c',
+                      'src/core/transport/metadata_batch.c',
+                      'src/core/transport/static_metadata.c',
                       'src/core/transport/transport.c',
                       'src/core/transport/transport_op_string.c',
                       'third_party/nanopb/pb_common.c',
@@ -469,8 +479,10 @@ Pod::Spec.new do |s|
                               'src/core/channel/http_client_filter.h',
                               'src/core/channel/http_server_filter.h',
                               'src/core/channel/noop_filter.h',
+                              'src/core/channel/subchannel_call_holder.h',
                               'src/core/client_config/client_config.h',
                               'src/core/client_config/connector.h',
+                              'src/core/client_config/initial_connect_string.h',
                               'src/core/client_config/lb_policies/load_balancer_api.h',
                               'src/core/client_config/lb_policies/pick_first.h',
                               'src/core/client_config/lb_policies/round_robin.h',
@@ -487,6 +499,7 @@ Pod::Spec.new do |s|
                               'src/core/client_config/subchannel_factory_decorators/add_channel_arg.h',
                               'src/core/client_config/subchannel_factory_decorators/merge_channel_args.h',
                               'src/core/client_config/uri_parser.h',
+                              'src/core/compression/algorithm_metadata.h',
                               'src/core/compression/message_compress.h',
                               'src/core/debug/trace.h',
                               'src/core/httpcli/format_request.h',
@@ -537,7 +550,6 @@ Pod::Spec.new do |s|
                               'src/core/statistics/census_interface.h',
                               'src/core/statistics/census_rpc_stats.h',
                               'src/core/surface/api_trace.h',
-                              'src/core/surface/byte_buffer_queue.h',
                               'src/core/surface/call.h',
                               'src/core/surface/call_test_only.h',
                               'src/core/surface/channel.h',
@@ -546,6 +558,7 @@ Pod::Spec.new do |s|
                               'src/core/surface/init.h',
                               'src/core/surface/server.h',
                               'src/core/surface/surface_trace.h',
+                              'src/core/transport/byte_stream.h',
                               'src/core/transport/chttp2/alpn.h',
                               'src/core/transport/chttp2/bin_encoder.h',
                               'src/core/transport/chttp2/frame.h',
@@ -555,6 +568,7 @@ Pod::Spec.new do |s|
                               'src/core/transport/chttp2/frame_rst_stream.h',
                               'src/core/transport/chttp2/frame_settings.h',
                               'src/core/transport/chttp2/frame_window_update.h',
+                              'src/core/transport/chttp2/hpack_encoder.h',
                               'src/core/transport/chttp2/hpack_parser.h',
                               'src/core/transport/chttp2/hpack_table.h',
                               'src/core/transport/chttp2/http2_errors.h',
@@ -562,14 +576,14 @@ Pod::Spec.new do |s|
                               'src/core/transport/chttp2/incoming_metadata.h',
                               'src/core/transport/chttp2/internal.h',
                               'src/core/transport/chttp2/status_conversion.h',
-                              'src/core/transport/chttp2/stream_encoder.h',
                               'src/core/transport/chttp2/stream_map.h',
                               'src/core/transport/chttp2/timeout_encoding.h',
                               'src/core/transport/chttp2/varint.h',
                               'src/core/transport/chttp2_transport.h',
                               'src/core/transport/connectivity_state.h',
                               'src/core/transport/metadata.h',
-                              'src/core/transport/stream_op.h',
+                              'src/core/transport/metadata_batch.h',
+                              'src/core/transport/static_metadata.h',
                               'src/core/transport/transport.h',
                               'src/core/transport/transport_impl.h',
                               'third_party/nanopb/pb.h',
@@ -592,7 +606,7 @@ Pod::Spec.new do |s|
 
     ss.requires_arc = false
     ss.libraries = 'z'
-    ss.dependency 'OpenSSL', '~> 1.0.200'
+    ss.dependency 'OpenSSL', '~> 1.0.204.1'
 
     # ss.compiler_flags = '-GCC_WARN_INHIBIT_ALL_WARNINGS', '-w'
   end

include/grpc++/alarm.h

@@ -43,7 +43,7 @@
 namespace grpc {
 
 /// A thin wrapper around \a grpc_alarm (see / \a / src/core/surface/alarm.h).
-class Alarm: public GrpcLibrary {
+class Alarm : public GrpcLibrary {
  public:
   /// Create a completion queue alarm instance associated to \a cq.
   ///

include/grpc++/channel.h

@@ -47,8 +47,8 @@ namespace grpc {
 class CallOpSetInterface;
 class ChannelArguments;
 class CompletionQueue;
-class Credentials;
-class SecureCredentials;
+class ChannelCredentials;
+class SecureChannelCredentials;
 
 template <class R>
 class ClientReader;

include/grpc++/client_context.h

@@ -53,15 +53,16 @@
 #include <memory>
 #include <string>
 
-#include <grpc/compression.h>
-#include <grpc/grpc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/time.h>
+#include <grpc++/impl/sync.h>
 #include <grpc++/security/auth_context.h>
 #include <grpc++/support/config.h>
 #include <grpc++/support/status.h>
 #include <grpc++/support/string_ref.h>
 #include <grpc++/support/time.h>
+#include <grpc/compression.h>
+#include <grpc/grpc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/time.h>
 
 struct census_context;
 
@@ -69,7 +70,7 @@ namespace grpc {
 
 class Channel;
 class CompletionQueue;
-class Credentials;
+class CallCredentials;
 class RpcMethod;
 template <class R>
 class ClientReader;
@@ -244,7 +245,7 @@ class ClientContext {
   /// call.
   ///
   /// \see  https://github.com/grpc/grpc/blob/master/doc/grpc-auth-support.md
-  void set_credentials(const std::shared_ptr<Credentials>& creds) {
+  void set_credentials(const std::shared_ptr<CallCredentials>& creds) {
     creds_ = creds;
   }
 
@@ -315,10 +316,12 @@ class ClientContext {
 
   bool initial_metadata_received_;
   std::shared_ptr<Channel> channel_;
+  grpc::mutex mu_;
   grpc_call* call_;
+  bool call_canceled_;
   gpr_timespec deadline_;
   grpc::string authority_;
-  std::shared_ptr<Credentials> creds_;
+  std::shared_ptr<CallCredentials> creds_;
   mutable std::shared_ptr<const AuthContext> auth_context_;
   struct census_context* census_context_;
   std::multimap<grpc::string, grpc::string> send_initial_metadata_;

include/grpc++/create_channel.h

@@ -49,7 +49,8 @@ namespace grpc {
 /// an object or is invalid, a lame channel is returned.
 /// \param args Options for channel creation.
 std::shared_ptr<Channel> CreateChannel(
-    const grpc::string& target, const std::shared_ptr<Credentials>& creds);
+    const grpc::string& target,
+    const std::shared_ptr<ChannelCredentials>& creds);
 
 /// Create a new \em custom \a Channel pointing to \a target
 ///
@@ -61,7 +62,8 @@ std::shared_ptr<Channel> CreateChannel(
 /// an object or is invalid, a lame channel is returned.
 /// \param args Options for channel creation.
 std::shared_ptr<Channel> CreateCustomChannel(
-    const grpc::string& target, const std::shared_ptr<Credentials>& creds,
+    const grpc::string& target,
+    const std::shared_ptr<ChannelCredentials>& creds,
     const ChannelArguments& args);
 
 }  // namespace grpc

src/core/surface/byte_buffer_queue.h → include/grpc++/impl/server_builder_option.h

@@ -31,32 +31,21 @@
  *
  */
 
-#ifndef GRPC_INTERNAL_CORE_SURFACE_BYTE_BUFFER_QUEUE_H
-#define GRPC_INTERNAL_CORE_SURFACE_BYTE_BUFFER_QUEUE_H
+#ifndef GRPCXX_IMPL_SERVER_BUILDER_OPTION_H
+#define GRPCXX_IMPL_SERVER_BUILDER_OPTION_H
 
-#include <grpc/byte_buffer.h>
+#include <grpc++/support/channel_arguments.h>
 
-/* TODO(ctiller): inline an element or two into this struct to avoid per-call
-                  allocations */
-typedef struct {
-  grpc_byte_buffer **data;
-  size_t count;
-  size_t capacity;
-} grpc_bbq_array;
+namespace grpc {
 
-/* should be initialized by zeroing memory */
-typedef struct {
-  size_t drain_pos;
-  grpc_bbq_array filling;
-  grpc_bbq_array draining;
-  size_t bytes;
-} grpc_byte_buffer_queue;
+/// Interface to pass an option to a \a ServerBuilder.
+class ServerBuilderOption {
+ public:
+  virtual ~ServerBuilderOption() {}
+  /// Alter the \a ChannelArguments used to create the gRPC server.
+  virtual void UpdateArguments(ChannelArguments* args) = 0;
+};
 
-void grpc_bbq_destroy(grpc_byte_buffer_queue *q);
-grpc_byte_buffer *grpc_bbq_pop(grpc_byte_buffer_queue *q);
-void grpc_bbq_flush(grpc_byte_buffer_queue *q);
-int grpc_bbq_empty(grpc_byte_buffer_queue *q);
-void grpc_bbq_push(grpc_byte_buffer_queue *q, grpc_byte_buffer *bb);
-size_t grpc_bbq_bytes(grpc_byte_buffer_queue *q);
+}  // namespace grpc
 
-#endif /* GRPC_INTERNAL_CORE_SURFACE_BYTE_BUFFER_QUEUE_H */
+#endif  // GRPCXX_IMPL_SERVER_BUILDER_OPTION_H

include/grpc++/impl/thd_no_cxx11.h

@@ -46,10 +46,21 @@ class thread {
     joined_ = false;
     start();
   }
+  template <class T, class U>
+  thread(void (T::*fptr)(U arg), T *obj, U arg) {
+    func_ = new thread_function_arg<T, U>(fptr, obj, arg);
+    joined_ = false;
+    start();
+  }
   ~thread() {
     if (!joined_) std::terminate();
     delete func_;
   }
+  thread(thread &&other)
+      : func_(other.func_), thd_(other.thd_), joined_(other.joined_) {
+    other.joined_ = true;
+    other.func_ = NULL;
+  }
   void join() {
     gpr_thd_join(thd_);
     joined_ = true;
@@ -80,6 +91,18 @@ class thread {
     void (T::*fptr_)();
     T *obj_;
   };
+  template <class T, class U>
+  class thread_function_arg : public thread_function_base {
+   public:
+    thread_function_arg(void (T::*fptr)(U arg), T *obj, U arg)
+        : fptr_(fptr), obj_(obj), arg_(arg) {}
+    virtual void call() { (obj_->*fptr_)(arg_); }
+
+   private:
+    void (T::*fptr_)(U arg);
+    T *obj_;
+    U arg_;
+  };
   thread_function_base *func_;
   gpr_thd_id thd_;
   bool joined_;

include/grpc++/security/credentials.h

@@ -38,6 +38,7 @@
 #include <memory>
 
 #include <grpc++/impl/grpc_library.h>
+#include <grpc++/security/auth_context.h>
 #include <grpc++/support/config.h>
 #include <grpc++/support/status.h>
 #include <grpc++/support/string_ref.h>
@@ -45,37 +46,60 @@
 namespace grpc {
 class ChannelArguments;
 class Channel;
-class SecureCredentials;
-
-/// A credentials object encapsulates all the state needed by a client to
-/// authenticate with a server and make various assertions, e.g., about the
-/// client’s identity, role, or whether it is authorized to make a particular
-/// call.
+class SecureChannelCredentials;
+class CallCredentials;
+class SecureCallCredentials;
+
+/// A channel credentials object encapsulates all the state needed by a client
+/// to authenticate with a server for a given channel.
+/// It can make various assertions, e.g., about the client’s identity, role
+/// for all the calls on that channel.
 ///
 /// \see https://github.com/grpc/grpc/blob/master/doc/grpc-auth-support.md
-class Credentials : public GrpcLibrary {
+class ChannelCredentials : public GrpcLibrary {
  public:
-  ~Credentials() GRPC_OVERRIDE;
-
-  /// Apply this instance's credentials to \a call.
-  virtual bool ApplyToCall(grpc_call* call) = 0;
+  ~ChannelCredentials() GRPC_OVERRIDE;
 
  protected:
-  friend std::shared_ptr<Credentials> CompositeCredentials(
-      const std::shared_ptr<Credentials>& creds1,
-      const std::shared_ptr<Credentials>& creds2);
+  friend std::shared_ptr<ChannelCredentials> CompositeChannelCredentials(
+      const std::shared_ptr<ChannelCredentials>& channel_creds,
+      const std::shared_ptr<CallCredentials>& call_creds);
 
-  virtual SecureCredentials* AsSecureCredentials() = 0;
+  virtual SecureChannelCredentials* AsSecureCredentials() = 0;
 
  private:
   friend std::shared_ptr<Channel> CreateCustomChannel(
-      const grpc::string& target, const std::shared_ptr<Credentials>& creds,
+      const grpc::string& target,
+      const std::shared_ptr<ChannelCredentials>& creds,
       const ChannelArguments& args);
 
   virtual std::shared_ptr<Channel> CreateChannel(
       const grpc::string& target, const ChannelArguments& args) = 0;
 };
 
+/// A call credentials object encapsulates the state needed by a client to
+/// authenticate with a server for a given call on a channel.
+///
+/// \see https://github.com/grpc/grpc/blob/master/doc/grpc-auth-support.md
+class CallCredentials : public GrpcLibrary {
+ public:
+  ~CallCredentials() GRPC_OVERRIDE;
+
+  /// Apply this instance's credentials to \a call.
+  virtual bool ApplyToCall(grpc_call* call) = 0;
+
+ protected:
+  friend std::shared_ptr<ChannelCredentials> CompositeChannelCredentials(
+      const std::shared_ptr<ChannelCredentials>& channel_creds,
+      const std::shared_ptr<CallCredentials>& call_creds);
+
+  friend std::shared_ptr<CallCredentials> CompositeCallCredentials(
+      const std::shared_ptr<CallCredentials>& creds1,
+      const std::shared_ptr<CallCredentials>& creds2);
+
+  virtual SecureCallCredentials* AsSecureCredentials() = 0;
+};
+
 /// Options used to build SslCredentials.
 struct SslCredentialsOptions {
   /// The buffer containing the PEM encoding of the server root certificates. If
@@ -106,10 +130,10 @@ struct SslCredentialsOptions {
 /// Using these credentials to connect to any other service may result in this
 /// service being able to impersonate your client for requests to Google
 /// services.
-std::shared_ptr<Credentials> GoogleDefaultCredentials();
+std::shared_ptr<ChannelCredentials> GoogleDefaultCredentials();
 
 /// Builds SSL Credentials given SSL specific options
-std::shared_ptr<Credentials> SslCredentials(
+std::shared_ptr<ChannelCredentials> SslCredentials(
     const SslCredentialsOptions& options);
 
 /// Builds credentials for use when running in GCE
@@ -118,14 +142,14 @@ std::shared_ptr<Credentials> SslCredentials(
 /// Using these credentials to connect to any other service may result in this
 /// service being able to impersonate your client for requests to Google
 /// services.
-std::shared_ptr<Credentials> GoogleComputeEngineCredentials();
+std::shared_ptr<CallCredentials> GoogleComputeEngineCredentials();
 
 /// Builds Service Account JWT Access credentials.
 /// json_key is the JSON key string containing the client's private key.
 /// token_lifetime_seconds is the lifetime in seconds of each Json Web Token
 /// (JWT) created with this credentials. It should not exceed
 /// grpc_max_auth_token_lifetime or will be cropped to this value.
-std::shared_ptr<Credentials> ServiceAccountJWTAccessCredentials(
+std::shared_ptr<CallCredentials> ServiceAccountJWTAccessCredentials(
     const grpc::string& json_key, long token_lifetime_seconds);
 
 /// Builds refresh token credentials.
@@ -136,7 +160,7 @@ std::shared_ptr<Credentials> ServiceAccountJWTAccessCredentials(
 /// Using these credentials to connect to any other service may result in this
 /// service being able to impersonate your client for requests to Google
 /// services.
-std::shared_ptr<Credentials> GoogleRefreshTokenCredentials(
+std::shared_ptr<CallCredentials> GoogleRefreshTokenCredentials(
     const grpc::string& json_refresh_token);
 
 /// Builds access token credentials.
@@ -147,7 +171,7 @@ std::shared_ptr<Credentials> GoogleRefreshTokenCredentials(
 /// Using these credentials to connect to any other service may result in this
 /// service being able to impersonate your client for requests to Google
 /// services.
-std::shared_ptr<Credentials> AccessTokenCredentials(
+std::shared_ptr<CallCredentials> AccessTokenCredentials(
     const grpc::string& access_token);
 
 /// Builds IAM credentials.
@@ -156,17 +180,23 @@ std::shared_ptr<Credentials> AccessTokenCredentials(
 /// Using these credentials to connect to any other service may result in this
 /// service being able to impersonate your client for requests to Google
 /// services.
-std::shared_ptr<Credentials> GoogleIAMCredentials(
+std::shared_ptr<CallCredentials> GoogleIAMCredentials(
     const grpc::string& authorization_token,
     const grpc::string& authority_selector);
 
-/// Combines two credentials objects into a composite credentials
-std::shared_ptr<Credentials> CompositeCredentials(
-    const std::shared_ptr<Credentials>& creds1,
-    const std::shared_ptr<Credentials>& creds2);
+/// Combines a channel credentials and a call credentials into a composite
+/// channel credentials.
+std::shared_ptr<ChannelCredentials> CompositeChannelCredentials(
+    const std::shared_ptr<ChannelCredentials>& channel_creds,
+    const std::shared_ptr<CallCredentials>& call_creds);
+
+/// Combines two call credentials objects into a composite call credentials.
+std::shared_ptr<CallCredentials> CompositeCallCredentials(
+    const std::shared_ptr<CallCredentials>& creds1,
+    const std::shared_ptr<CallCredentials>& creds2);
 
 /// Credentials for an unencrypted, unauthenticated channel
-std::shared_ptr<Credentials> InsecureCredentials();
+std::shared_ptr<ChannelCredentials> InsecureChannelCredentials();
 
 // User defined metadata credentials.
 class MetadataCredentialsPlugin {
@@ -177,13 +207,21 @@ class MetadataCredentialsPlugin {
   // a different thread from the one processing the call.
   virtual bool IsBlocking() const { return true; }
 
+  // Type of credentials this plugin is implementing.
+  virtual const char* GetType() const { return ""; }
+
   // Gets the auth metatada produced by this plugin.
+  // The fully qualified method name is:
+  // service_url + "/" + method_name.
+  // The channel_auth_context contains (among other things), the identity of
+  // the server.
   virtual Status GetMetadata(
-      grpc::string_ref service_url,
+      grpc::string_ref service_url, grpc::string_ref method_name,
+      const AuthContext& channel_auth_context,
       std::multimap<grpc::string, grpc::string>* metadata) = 0;
 };
 
-std::shared_ptr<Credentials> MetadataCredentialsFromPlugin(
+std::shared_ptr<CallCredentials> MetadataCredentialsFromPlugin(
     std::unique_ptr<MetadataCredentialsPlugin> plugin);
 
 }  // namespace grpc

include/grpc++/server.h

@@ -37,14 +37,15 @@
 #include <list>
 #include <memory>
 
-#include <grpc/compression.h>
 #include <grpc++/completion_queue.h>
 #include <grpc++/impl/call.h>
 #include <grpc++/impl/grpc_library.h>
 #include <grpc++/impl/sync.h>
 #include <grpc++/security/server_credentials.h>
+#include <grpc++/support/channel_arguments.h>
 #include <grpc++/support/config.h>
 #include <grpc++/support/status.h>
+#include <grpc/compression.h>
 
 struct grpc_server;
 
@@ -56,6 +57,7 @@ class AsyncGenericService;
 class RpcService;
 class RpcServiceMethod;
 class ServerAsyncStreamingInterface;
+class ServerContext;
 class ThreadPoolInterface;
 
 /// Models a gRPC server.
@@ -84,6 +86,23 @@ class Server GRPC_FINAL : public GrpcLibrary, private CallHook {
   /// call \a Shutdown for this function to ever return.
   void Wait();
 
+  /// Global Callbacks
+  ///
+  /// Can be set exactly once per application to install hooks whenever
+  /// a server event occurs
+  class GlobalCallbacks {
+   public:
+    virtual ~GlobalCallbacks() {}
+    /// Called before application callback for each synchronous server request
+    virtual void PreSynchronousRequest(ServerContext* context) = 0;
+    /// Called after application callback for each synchronous server request
+    virtual void PostSynchronousRequest(ServerContext* context) = 0;
+  };
+  /// Set the global callback object. Can only be called once. Does not take
+  /// ownership of callbacks, and expects the pointed to object to be alive
+  /// until all server objects in the process have been destroyed.
+  static void SetGlobalCallbacks(GlobalCallbacks* callbacks);
+
  private:
   friend class AsyncGenericService;
   friend class AsynchronousService;
@@ -100,7 +119,7 @@ class Server GRPC_FINAL : public GrpcLibrary, private CallHook {
   /// \param max_message_size Maximum message length that the channel can
   /// receive.
   Server(ThreadPoolInterface* thread_pool, bool thread_pool_owned,
-         int max_message_size, grpc_compression_options compression_options);
+         int max_message_size, const ChannelArguments& args);
 
   /// Register a service. This call does not take ownership of the service.
   /// The service must exist for the lifetime of the Server instance.

include/grpc++/server_builder.h

@@ -37,8 +37,9 @@
 #include <memory>
 #include <vector>
 
-#include <grpc/compression.h>
+#include <grpc++/impl/server_builder_option.h>
 #include <grpc++/support/config.h>
+#include <grpc/compression.h>
 
 namespace grpc {
 
@@ -98,6 +99,8 @@ class ServerBuilder {
     compression_options_ = options;
   }
 
+  void SetOption(std::unique_ptr<ServerBuilderOption> option);
+
   /// Tries to bind \a server to the given \a addr.
   ///
   /// It can be invoked multiple times.
@@ -140,6 +143,7 @@ class ServerBuilder {
 
   int max_message_size_;
   grpc_compression_options compression_options_;
+  std::vector<std::unique_ptr<ServerBuilderOption>> options_;
   std::vector<std::unique_ptr<NamedService<RpcService>>> services_;
   std::vector<std::unique_ptr<NamedService<AsynchronousService>>>
       async_services_;

include/grpc++/support/channel_arguments.h

@@ -70,7 +70,8 @@ class ChannelArguments {
   void SetChannelArgs(grpc_channel_args* channel_args) const;
 
   // gRPC specific channel argument setters
-  /// Set target name override for SSL host name checking.
+  /// Set target name override for SSL host name checking. This option is for
+  /// testing only and should never be used in production.
   void SetSslTargetNameOverride(const grpc::string& name);
   // TODO(yangg) add flow control options
   /// Set the compression algorithm for the channel.
@@ -79,11 +80,16 @@ class ChannelArguments {
   // Generic channel argument setters. Only for advanced use cases.
   /// Set an integer argument \a value under \a key.
   void SetInt(const grpc::string& key, int value);
+
+  // Generic channel argument setter. Only for advanced use cases.
+  /// Set a pointer argument \a value under \a key. Owership is not transferred.
+  void SetPointer(const grpc::string& key, void* value);
+
   /// Set a textual argument \a value under \a key.
   void SetString(const grpc::string& key, const grpc::string& value);
 
  private:
-  friend class SecureCredentials;
+  friend class SecureChannelCredentials;
   friend class testing::ChannelArgumentsTest;
 
   // Returns empty string when it is not set.

include/grpc++/support/string_ref.h

@@ -56,7 +56,7 @@ class string_ref {
   typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
 
   // constants
-  const static size_t npos = size_t(-1);
+  const static size_t npos;
 
   // construct/copy.
   string_ref() : data_(nullptr), length_(0) {}

include/grpc++/support/time.h

@@ -35,6 +35,7 @@
 #define GRPCXX_SUPPORT_TIME_H
 
 #include <grpc++/support/config.h>
+#include <grpc/support/time.h>
 
 namespace grpc {
 

include/grpc/byte_buffer.h

@@ -106,6 +106,9 @@ void grpc_byte_buffer_reader_destroy(grpc_byte_buffer_reader *reader);
 int grpc_byte_buffer_reader_next(grpc_byte_buffer_reader *reader,
                                  gpr_slice *slice);
 
+/** Merge all data from \a reader into single slice */
+gpr_slice grpc_byte_buffer_reader_readall(grpc_byte_buffer_reader *reader);
+
 /** Returns a RAW byte buffer instance from the output of \a reader. */
 grpc_byte_buffer *grpc_raw_byte_buffer_from_reader(
     grpc_byte_buffer_reader *reader);

include/grpc/grpc.h

@@ -127,6 +127,17 @@ typedef struct {
 /** Initial sequence number for http2 transports */
 #define GRPC_ARG_HTTP2_INITIAL_SEQUENCE_NUMBER \
   "grpc.http2.initial_sequence_number"
+/** Amount to read ahead on individual streams. Defaults to 64kb, larger
+    values can help throughput on high-latency connections.
+    NOTE: at some point we'd like to auto-tune this, and this parameter
+    will become a no-op. */
+#define GRPC_ARG_HTTP2_STREAM_LOOKAHEAD_BYTES "grpc.http2.lookahead_bytes"
+/** How much memory to use for hpack decoding */
+#define GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER \
+  "grpc.http2.hpack_table_size.decoder"
+/** How much memory to use for hpack encoding */
+#define GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_ENCODER \
+  "grpc.http2.hpack_table_size.encoder"
 /** Default authority to pass if none specified on call construction */
 #define GRPC_ARG_DEFAULT_AUTHORITY "grpc.default_authority"
 /** Primary user agent: goes at the start of the user-agent metadata

include/grpc/grpc_security.h

@@ -41,15 +41,91 @@
 extern "C" {
 #endif
 
-/* --- grpc_credentials object. ---
+/* --- Authentication Context. --- */
+
+#define GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME "transport_security_type"
+#define GRPC_SSL_TRANSPORT_SECURITY_TYPE "ssl"
+
+#define GRPC_X509_CN_PROPERTY_NAME "x509_common_name"
+#define GRPC_X509_SAN_PROPERTY_NAME "x509_subject_alternative_name"
+
+typedef struct grpc_auth_context grpc_auth_context;
+
+typedef struct grpc_auth_property_iterator {
+  const grpc_auth_context *ctx;
+  size_t index;
+  const char *name;
+} grpc_auth_property_iterator;
+
+/* value, if not NULL, is guaranteed to be NULL terminated. */
+typedef struct grpc_auth_property {
+  char *name;
+  char *value;
+  size_t value_length;
+} grpc_auth_property;
 
-   A credentials object represents a way to authenticate a client.  */
+/* Returns NULL when the iterator is at the end. */
+const grpc_auth_property *grpc_auth_property_iterator_next(
+    grpc_auth_property_iterator *it);
 
-typedef struct grpc_credentials grpc_credentials;
+/* Iterates over the auth context. */
+grpc_auth_property_iterator grpc_auth_context_property_iterator(
+    const grpc_auth_context *ctx);
 
-/* Releases a credentials object.
+/* Gets the peer identity. Returns an empty iterator (first _next will return
+   NULL) if the peer is not authenticated. */
+grpc_auth_property_iterator grpc_auth_context_peer_identity(
+    const grpc_auth_context *ctx);
+
+/* Finds a property in the context. May return an empty iterator (first _next
+   will return NULL) if no property with this name was found in the context. */
+grpc_auth_property_iterator grpc_auth_context_find_properties_by_name(
+    const grpc_auth_context *ctx, const char *name);
+
+/* Gets the name of the property that indicates the peer identity. Will return
+   NULL if the peer is not authenticated. */
+const char *grpc_auth_context_peer_identity_property_name(
+    const grpc_auth_context *ctx);
+
+/* Returns 1 if the peer is authenticated, 0 otherwise. */
+int grpc_auth_context_peer_is_authenticated(const grpc_auth_context *ctx);
+
+/* Gets the auth context from the call. Caller needs to call
+   grpc_auth_context_release on the returned context. */
+grpc_auth_context *grpc_call_auth_context(grpc_call *call);
+
+/* Releases the auth context returned from grpc_call_auth_context. */
+void grpc_auth_context_release(grpc_auth_context *context);
+
+/* --
+   The following auth context methods should only be called by a server metadata
+   processor to set properties extracted from auth metadata.
+   -- */
+
+/* Add a property. */
+void grpc_auth_context_add_property(grpc_auth_context *ctx, const char *name,
+                                    const char *value, size_t value_length);
+
+/* Add a C string property. */
+void grpc_auth_context_add_cstring_property(grpc_auth_context *ctx,
+                                            const char *name,
+                                            const char *value);
+
+/* Sets the property name. Returns 1 if successful or 0 in case of failure
+   (which means that no property with this name exists). */
+int grpc_auth_context_set_peer_identity_property_name(grpc_auth_context *ctx,
+                                                      const char *name);
+
+/* --- grpc_channel_credentials object. ---
+
+   A channel credentials object represents a way to authenticate a client on a
+   channel.  */
+
+typedef struct grpc_channel_credentials grpc_channel_credentials;
+
+/* Releases a channel credentials object.
    The creator of the credentials object is responsible for its release. */
-void grpc_credentials_release(grpc_credentials *creds);
+void grpc_channel_credentials_release(grpc_channel_credentials *creds);
 
 /* Environment variable that points to the google default application
    credentials json key or refresh token. Used in the
@@ -59,7 +135,7 @@ void grpc_credentials_release(grpc_credentials *creds);
 /* Creates default credentials to connect to a google gRPC service.
    WARNING: Do NOT use this credentials to connect to a non-google service as
    this could result in an oauth2 token leak. */
-grpc_credentials *grpc_google_default_credentials_create(void);
+grpc_channel_credentials *grpc_google_default_credentials_create(void);
 
 /* Environment variable that points to the default SSL roots file. This file
    must be a PEM encoded file with all the roots such as the one that can be
@@ -88,19 +164,37 @@ typedef struct {
    - pem_key_cert_pair is a pointer on the object containing client's private
      key and certificate chain. This parameter can be NULL if the client does
      not have such a key/cert pair. */
-grpc_credentials *grpc_ssl_credentials_create(
+grpc_channel_credentials *grpc_ssl_credentials_create(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pair,
     void *reserved);
 
-/* Creates a composite credentials object. */
-grpc_credentials *grpc_composite_credentials_create(grpc_credentials *creds1,
-                                                    grpc_credentials *creds2,
-                                                    void *reserved);
+/* --- grpc_call_credentials object.
+
+   A call credentials object represents a way to authenticate on a particular
+   call. These credentials can be composed with a channel credentials object
+   so that they are sent with every call on this channel.  */
+
+typedef struct grpc_call_credentials grpc_call_credentials;
+
+/* Releases a call credentials object.
+   The creator of the credentials object is responsible for its release. */
+void grpc_call_credentials_release(grpc_call_credentials *creds);
+
+/* Creates a composite channel credentials object. */
+grpc_channel_credentials *grpc_composite_channel_credentials_create(
+    grpc_channel_credentials *channel_creds, grpc_call_credentials *call_creds,
+    void *reserved);
+
+/* Creates a composite call credentials object. */
+grpc_call_credentials *grpc_composite_call_credentials_create(
+    grpc_call_credentials *creds1, grpc_call_credentials *creds2,
+    void *reserved);
 
 /* Creates a compute engine credentials object for connecting to Google.
    WARNING: Do NOT use this credentials to connect to a non-google service as
    this could result in an oauth2 token leak. */
-grpc_credentials *grpc_google_compute_engine_credentials_create(void *reserved);
+grpc_call_credentials *grpc_google_compute_engine_credentials_create(
+    void *reserved);
 
 extern const gpr_timespec grpc_max_auth_token_lifetime;
 
@@ -109,7 +203,7 @@ extern const gpr_timespec grpc_max_auth_token_lifetime;
    - token_lifetime is the lifetime of each Json Web Token (JWT) created with
      this credentials.  It should not exceed grpc_max_auth_token_lifetime or
      will be cropped to this value.  */
-grpc_credentials *grpc_service_account_jwt_access_credentials_create(
+grpc_call_credentials *grpc_service_account_jwt_access_credentials_create(
     const char *json_key, gpr_timespec token_lifetime, void *reserved);
 
 /* Creates an Oauth2 Refresh Token credentials object for connecting to Google.
@@ -118,16 +212,16 @@ grpc_credentials *grpc_service_account_jwt_access_credentials_create(
    this could result in an oauth2 token leak.
    - json_refresh_token is the JSON string containing the refresh token itself
      along with a client_id and client_secret. */
-grpc_credentials *grpc_google_refresh_token_credentials_create(
+grpc_call_credentials *grpc_google_refresh_token_credentials_create(
     const char *json_refresh_token, void *reserved);
 
 /* Creates an Oauth2 Access Token credentials with an access token that was
    aquired by an out of band mechanism. */
-grpc_credentials *grpc_access_token_credentials_create(const char *access_token,
-                                                       void *reserved);
+grpc_call_credentials *grpc_access_token_credentials_create(
+    const char *access_token, void *reserved);
 
 /* Creates an IAM credentials object for connecting to Google. */
-grpc_credentials *grpc_google_iam_credentials_create(
+grpc_call_credentials *grpc_google_iam_credentials_create(
     const char *authorization_token, const char *authority_selector,
     void *reserved);
 
@@ -146,6 +240,24 @@ typedef void (*grpc_credentials_plugin_metadata_cb)(
     void *user_data, const grpc_metadata *creds_md, size_t num_creds_md,
     grpc_status_code status, const char *error_details);
 
+/* Context that can be used by metadata credentials plugin in order to create
+   auth related metadata. */
+typedef struct {
+  /* The fully qualifed service url. */
+  const char *service_url;
+
+  /* The method name of the RPC being called (not fully qualified).
+     The fully qualified method name can be built from the service_url:
+     full_qualified_method_name = ctx->service_url + '/' + ctx->method_name. */
+  const char *method_name;
+
+  /* The auth_context of the channel which gives the server's identity. */
+  const grpc_auth_context *channel_auth_context;
+
+  /* Reserved for future use. */
+  void *reserved;
+} grpc_auth_metadata_context;
+
 /* grpc_metadata_credentials plugin is an API user provided structure used to
    create grpc_credentials objects that can be set on a channel (composed) or
    a call. See grpc_credentials_metadata_create_from_plugin below.
@@ -153,11 +265,11 @@ typedef void (*grpc_credentials_plugin_metadata_cb)(
    every call in scope for the credentials created from it. */
 typedef struct {
   /* The implementation of this method has to be non-blocking.
-     - service_url is the fully qualified URL that the client stack is
-       connecting to.
+     - context is the information that can be used by the plugin to create auth
+       metadata.
      - cb is the callback that needs to be called when the metadata is ready.
      - user_data needs to be passed as the first parameter of the callback. */
-  void (*get_metadata)(void *state, const char *service_url,
+  void (*get_metadata)(void *state, grpc_auth_metadata_context context,
                        grpc_credentials_plugin_metadata_cb cb, void *user_data);
 
   /* Destroys the plugin state. */
@@ -165,16 +277,19 @@ typedef struct {
 
   /* State that will be set as the first parameter of the methods above. */
   void *state;
+
+  /* Type of credentials that this plugin is implementing. */
+  const char *type;
 } grpc_metadata_credentials_plugin;
 
 /* Creates a credentials object from a plugin. */
-grpc_credentials *grpc_metadata_credentials_create_from_plugin(
+grpc_call_credentials *grpc_metadata_credentials_create_from_plugin(
     grpc_metadata_credentials_plugin plugin, void *reserved);
 
 /* --- Secure channel creation. --- */
 
 /* Creates a secure channel using the passed-in credentials. */
-grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
+grpc_channel *grpc_secure_channel_create(grpc_channel_credentials *creds,
                                          const char *target,
                                          const grpc_channel_args *args,
                                          void *reserved);
@@ -218,82 +333,7 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
 /* Sets a credentials to a call. Can only be called on the client side before
    grpc_call_start_batch. */
 grpc_call_error grpc_call_set_credentials(grpc_call *call,
-                                          grpc_credentials *creds);
-
-/* --- Authentication Context. --- */
-
-#define GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME "transport_security_type"
-#define GRPC_SSL_TRANSPORT_SECURITY_TYPE "ssl"
-
-#define GRPC_X509_CN_PROPERTY_NAME "x509_common_name"
-#define GRPC_X509_SAN_PROPERTY_NAME "x509_subject_alternative_name"
-
-typedef struct grpc_auth_context grpc_auth_context;
-
-typedef struct grpc_auth_property_iterator {
-  const grpc_auth_context *ctx;
-  size_t index;
-  const char *name;
-} grpc_auth_property_iterator;
-
-/* value, if not NULL, is guaranteed to be NULL terminated. */
-typedef struct grpc_auth_property {
-  char *name;
-  char *value;
-  size_t value_length;
-} grpc_auth_property;
-
-/* Returns NULL when the iterator is at the end. */
-const grpc_auth_property *grpc_auth_property_iterator_next(
-    grpc_auth_property_iterator *it);
-
-/* Iterates over the auth context. */
-grpc_auth_property_iterator grpc_auth_context_property_iterator(
-    const grpc_auth_context *ctx);
-
-/* Gets the peer identity. Returns an empty iterator (first _next will return
-   NULL) if the peer is not authenticated. */
-grpc_auth_property_iterator grpc_auth_context_peer_identity(
-    const grpc_auth_context *ctx);
-
-/* Finds a property in the context. May return an empty iterator (first _next
-   will return NULL) if no property with this name was found in the context. */
-grpc_auth_property_iterator grpc_auth_context_find_properties_by_name(
-    const grpc_auth_context *ctx, const char *name);
-
-/* Gets the name of the property that indicates the peer identity. Will return
-   NULL if the peer is not authenticated. */
-const char *grpc_auth_context_peer_identity_property_name(
-    const grpc_auth_context *ctx);
-
-/* Returns 1 if the peer is authenticated, 0 otherwise. */
-int grpc_auth_context_peer_is_authenticated(const grpc_auth_context *ctx);
-
-/* Gets the auth context from the call. Caller needs to call
-   grpc_auth_context_release on the returned context. */
-grpc_auth_context *grpc_call_auth_context(grpc_call *call);
-
-/* Releases the auth context returned from grpc_call_auth_context. */
-void grpc_auth_context_release(grpc_auth_context *context);
-
-/* --
-   The following auth context methods should only be called by a server metadata
-   processor to set properties extracted from auth metadata.
-   -- */
-
-/* Add a property. */
-void grpc_auth_context_add_property(grpc_auth_context *ctx, const char *name,
-                                    const char *value, size_t value_length);
-
-/* Add a C string property. */
-void grpc_auth_context_add_cstring_property(grpc_auth_context *ctx,
-                                            const char *name,
-                                            const char *value);
-
-/* Sets the property name. Returns 1 if successful or 0 in case of failure
-   (which means that no property with this name exists). */
-int grpc_auth_context_set_peer_identity_property_name(grpc_auth_context *ctx,
-                                                      const char *name);
+                                          grpc_call_credentials *creds);
 
 /* --- Auth Metadata Processing --- */
 

include/grpc/support/avl.h

@@ -0,0 +1,91 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_SUPPORT_AVL_H
+#define GRPC_SUPPORT_AVL_H
+
+#include <grpc/support/sync.h>
+
+/** internal node of an AVL tree */
+typedef struct gpr_avl_node {
+  gpr_refcount refs;
+  void *key;
+  void *value;
+  struct gpr_avl_node *left;
+  struct gpr_avl_node *right;
+  long height;
+} gpr_avl_node;
+
+typedef struct gpr_avl_vtable {
+  /** destroy a key */
+  void (*destroy_key)(void *key);
+  /** copy a key, returning new value */
+  void *(*copy_key)(void *key);
+  /** compare key1, key2; return <0 if key1 < key2,
+      >0 if key1 > key2, 0 if key1 == key2 */
+  long (*compare_keys)(void *key1, void *key2);
+  /** destroy a value */
+  void (*destroy_value)(void *value);
+  /** copy a value */
+  void *(*copy_value)(void *value);
+} gpr_avl_vtable;
+
+/** "pointer" to an AVL tree - this is a reference
+    counted object - use gpr_avl_ref to add a reference,
+    gpr_avl_unref when done with a reference */
+typedef struct gpr_avl {
+  const gpr_avl_vtable *vtable;
+  gpr_avl_node *root;
+} gpr_avl;
+
+/** create an immutable AVL tree */
+gpr_avl gpr_avl_create(const gpr_avl_vtable *vtable);
+/** add a reference to an existing tree - returns
+    the tree as a convenience */
+gpr_avl gpr_avl_ref(gpr_avl avl);
+/** remove a reference to a tree - destroying it if there
+    are no references left */
+void gpr_avl_unref(gpr_avl avl);
+/** return a new tree with (key, value) added to avl.
+    implicitly unrefs avl to allow easy chaining.
+    if key exists in avl, the new tree's key entry updated
+    (i.e. a duplicate is not created) */
+gpr_avl gpr_avl_add(gpr_avl avl, void *key, void *value);
+/** return a new tree with key deleted */
+gpr_avl gpr_avl_remove(gpr_avl avl, void *key);
+/** lookup key, and return the associated value.
+    does not mutate avl.
+    returns NULL if key is not found. */
+void *gpr_avl_get(gpr_avl avl, void *key);
+
+#endif

include/grpc/support/histogram.h

@@ -50,7 +50,7 @@ void gpr_histogram_add(gpr_histogram *h, double x);
 /* The following merges the second histogram into the first. It only works
    if they have the same buckets and resolution. Returns 0 on failure, 1
    on success */
-int gpr_histogram_merge(gpr_histogram *dst, gpr_histogram *src);
+int gpr_histogram_merge(gpr_histogram *dst, const gpr_histogram *src);
 
 double gpr_histogram_percentile(gpr_histogram *histogram, double percentile);
 double gpr_histogram_mean(gpr_histogram *histogram);

include/grpc/support/port_platform.h

@@ -181,9 +181,9 @@
 #ifndef _BSD_SOURCE
 #define _BSD_SOURCE
 #endif
-#define GPR_FORBID_UNREACHABLE_CODE
 #define GPR_MSG_IOVLEN_TYPE int
 #if TARGET_OS_IPHONE
+#define GPR_FORBID_UNREACHABLE_CODE
 #define GPR_PLATFORM_STRING "ios"
 #define GPR_CPU_IPHONE 1
 #define GPR_PTHREAD_TLS 1

include/grpc/support/slice.h

@@ -144,6 +144,9 @@ gpr_slice gpr_slice_from_copied_string(const char *source);
      memcpy(slice->data, source, len); */
 gpr_slice gpr_slice_from_copied_buffer(const char *source, size_t len);
 
+/* Create a slice pointing to constant memory */
+gpr_slice gpr_slice_from_static_string(const char *source);
+
 /* Return a result slice derived from s, which shares a ref count with s, where
    result.data==s.data+begin, and result.length==end-begin.
    The ref count of s is increased by one.

include/grpc/support/slice_buffer.h

@@ -89,6 +89,11 @@ void gpr_slice_buffer_move_into(gpr_slice_buffer *src, gpr_slice_buffer *dst);
 /* remove n bytes from the end of a slice buffer */
 void gpr_slice_buffer_trim_end(gpr_slice_buffer *src, size_t n,
                                gpr_slice_buffer *garbage);
+/* move the first n bytes of src into dst */
+void gpr_slice_buffer_move_first(gpr_slice_buffer *src, size_t n,
+                                 gpr_slice_buffer *dst);
+/* take the first slice in the slice buffer */
+gpr_slice gpr_slice_buffer_take_first(gpr_slice_buffer *src);
 
 #ifdef __cplusplus
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "grpc",
-  "version": "0.11.1",
+  "version": "0.12.0",
   "author": "Google Inc.",
   "description": "gRPC Library for Node",
   "homepage": "http://www.grpc.io/",

reports/interop_html_report.template

@@ -0,0 +1,141 @@
+<!DOCTYPE html>
+<html lang="en">
+<head><title>Interop Test Result</title></head>
+<body>
+
+<%def name="fill_one_test_result(shortname, resultset)">
+  % if shortname in resultset:
+    ## Because interop tests does not have runs_per_test flag, each test is 
+    ## run once. So there should only be one element for each result.
+    <% result = resultset[shortname][0] %>
+    % if result.state == 'PASSED':      
+        <td bgcolor="green">PASS</td>
+    % else:
+      <% 
+        tooltip = ''
+        if result.returncode > 0 or result.message:
+          if result.returncode > 0:
+            tooltip = 'returncode: %d ' % result.returncode
+          if result.message:
+            tooltip = '%smessage: %s' % (tooltip, result.message)  
+      %>     
+      % if result.state == 'FAILED':
+        <td bgcolor="red">
+        % if tooltip:  
+          <a href="#" data-toggle="tooltip" data-placement="auto" title="${tooltip | h}">FAIL</a></td>
+        % else:
+          FAIL</td>
+        % endif
+      % elif result.state == 'TIMEOUT':
+        <td bgcolor="yellow">
+        % if tooltip:
+          <a href="#" data-toggle="tooltip" data-placement="auto" title="${tooltip | h}">TIMEOUT</a></td> 
+        % else:
+          TIMEOUT</td>
+        % endif
+      % endif
+    % endif
+  % else:
+     <td bgcolor="magenta">Not implemented</td>
+  % endif
+</%def>
+
+% if num_failures > 1:
+  <p><h2><font color="red">${num_failures} tests failed!</font></h2></p>
+% elif num_failures:
+  <p><h2><font color="red">${num_failures} test failed!</font></h2></p>
+% else:
+  <p><h2><font color="green">All tests passed!</font></h2></p>
+% endif
+
+% if cloud_to_prod:
+  ## Each column header is the client language.
+  <h2>Cloud to Prod</h2>
+  <table style="width:100%" border="1">
+  <tr bgcolor="#00BFFF">
+  <th>Client languages &#9658;<br/>Test Cases &#9660;</th>
+  % for client_lang in client_langs:
+    <th>${client_lang}</th>
+  % endfor
+  </tr>
+  % for test_case in test_cases + auth_test_cases:
+    <tr><td><b>${test_case}</b></td>
+    % for client_lang in client_langs:
+      <% 
+        if test_case in auth_test_cases:
+          shortname = 'cloud_to_prod_auth:%s:%s' % (client_lang, test_case)
+        else:
+          shortname = 'cloud_to_prod:%s:%s' % (client_lang, test_case)
+      %>
+      ${fill_one_test_result(shortname, resultset)}
+    % endfor
+    </tr> 
+  % endfor
+  </table>
+% endif
+
+% if http2_interop:
+  ## Each column header is the server language.
+  <h2>HTTP/2 Interop</h2> 
+  <table style="width:100%" border="1">
+  <tr bgcolor="#00BFFF">
+  <th>Servers &#9658;<br/>Test Cases &#9660;</th>
+  % for server_lang in server_langs:
+    <th>${server_lang}</th>
+  % endfor
+  % if cloud_to_prod:
+    <th>prod</th>
+  % endif
+  </tr>
+  % for test_case in http2_cases:
+    <tr><td><b>${test_case}</b></td>
+    ## Fill up the cells with test result.
+    % for server_lang in server_langs:
+      <% 
+        shortname = 'cloud_to_cloud:http2:%s_server:%s' % (
+            server_lang, test_case)
+      %>
+      ${fill_one_test_result(shortname, resultset)}
+    % endfor
+    % if cloud_to_prod:
+      <% shortname = 'cloud_to_prod:http2:%s' % test_case %>
+      ${fill_one_test_result(shortname, resultset)}
+    % endif
+    </tr>
+  % endfor
+  </table>
+% endif
+
+% if server_langs:
+  % for test_case in test_cases:
+    ## Each column header is the client language.
+    <h2>${test_case}</h2> 
+    <table style="width:100%" border="1">
+    <tr bgcolor="#00BFFF">
+    <th>Client languages &#9658;<br/>Server languages &#9660;</th>
+    % for client_lang in client_langs:
+      <th>${client_lang}</th>
+    % endfor
+    </tr>
+    ## Each row head is the server language.
+    % for server_lang in server_langs:
+      <tr>
+      <td><b>${server_lang}</b></td>
+      % for client_lang in client_langs:
+        <% 
+          shortname = 'cloud_to_cloud:%s:%s_server:%s' % (
+              client_lang, server_lang, test_case)
+        %>
+        ${fill_one_test_result(shortname, resultset)}
+      % endfor
+      </tr>
+    % endfor
+    </table>
+  % endfor
+% endif
+
+<script>
+  $(document).ready(function(){$('[data-toggle="tooltip"]').tooltip();});
+</script>
+</body>
+</html>

src/core/census/grpc_filter.c

@@ -36,16 +36,18 @@
 #include <stdio.h>
 #include <string.h>
 
-#include "src/core/channel/channel_stack.h"
-#include "src/core/channel/noop_filter.h"
-#include "src/core/statistics/census_interface.h"
-#include "src/core/statistics/census_rpc_stats.h"
 #include <grpc/census.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/slice.h>
 #include <grpc/support/time.h>
 
+#include "src/core/channel/channel_stack.h"
+#include "src/core/channel/noop_filter.h"
+#include "src/core/statistics/census_interface.h"
+#include "src/core/statistics/census_rpc_stats.h"
+#include "src/core/transport/static_metadata.h"
+
 typedef struct call_data {
   census_op_id op_id;
   census_context *ctxt;
@@ -53,28 +55,24 @@ typedef struct call_data {
   int error;
 
   /* recv callback */
-  grpc_stream_op_buffer *recv_ops;
+  grpc_metadata_batch *recv_initial_metadata;
   grpc_closure *on_done_recv;
+  grpc_closure finish_recv;
 } call_data;
 
 typedef struct channel_data {
-  grpc_mdstr *path_str; /* pointer to meta data str with key == ":path" */
+  gpr_uint8 unused;
 } channel_data;
 
-static void extract_and_annotate_method_tag(grpc_stream_op_buffer *sopb,
+static void extract_and_annotate_method_tag(grpc_metadata_batch *md,
                                             call_data *calld,
                                             channel_data *chand) {
   grpc_linked_mdelem *m;
-  size_t i;
-  for (i = 0; i < sopb->nops; i++) {
-    grpc_stream_op *op = &sopb->ops[i];
-    if (op->type != GRPC_OP_METADATA) continue;
-    for (m = op->data.metadata.list.head; m != NULL; m = m->next) {
-      if (m->md->key == chand->path_str) {
-        gpr_log(GPR_DEBUG, "%s",
-                (const char *)GPR_SLICE_START_PTR(m->md->value->slice));
-        /* Add method tag here */
-      }
+  for (m = md->list.head; m != NULL; m = m->next) {
+    if (m->md->key == GRPC_MDSTR_PATH) {
+      gpr_log(GPR_DEBUG, "%s",
+              (const char *)GPR_SLICE_START_PTR(m->md->value->slice));
+      /* Add method tag here */
     }
   }
 }
@@ -83,8 +81,8 @@ static void client_mutate_op(grpc_call_element *elem,
                              grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  if (op->send_ops) {
-    extract_and_annotate_method_tag(op->send_ops, calld, chand);
+  if (op->send_initial_metadata) {
+    extract_and_annotate_method_tag(op->send_initial_metadata, calld, chand);
   }
 }
 
@@ -101,7 +99,7 @@ static void server_on_done_recv(grpc_exec_ctx *exec_ctx, void *ptr,
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   if (success) {
-    extract_and_annotate_method_tag(calld->recv_ops, calld, chand);
+    extract_and_annotate_method_tag(calld->recv_initial_metadata, calld, chand);
   }
   calld->on_done_recv->cb(exec_ctx, calld->on_done_recv->cb_arg, success);
 }
@@ -109,11 +107,11 @@ static void server_on_done_recv(grpc_exec_ctx *exec_ctx, void *ptr,
 static void server_mutate_op(grpc_call_element *elem,
                              grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
-  if (op->recv_ops) {
+  if (op->recv_initial_metadata) {
     /* substitute our callback for the op callback */
-    calld->recv_ops = op->recv_ops;
-    calld->on_done_recv = op->on_done_recv;
-    op->on_done_recv = calld->on_done_recv;
+    calld->recv_initial_metadata = op->recv_initial_metadata;
+    calld->on_done_recv = op->on_complete;
+    op->on_complete = &calld->finish_recv;
   }
 }
 
@@ -128,13 +126,11 @@ static void server_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 static void client_init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  const void *server_transport_data,
-                                  grpc_transport_stream_op *initial_op) {
+                                  grpc_call_element_args *args) {
   call_data *d = elem->call_data;
   GPR_ASSERT(d != NULL);
   memset(d, 0, sizeof(*d));
   d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
-  if (initial_op) client_mutate_op(elem, initial_op);
 }
 
 static void client_destroy_call_elem(grpc_exec_ctx *exec_ctx,
@@ -146,15 +142,13 @@ static void client_destroy_call_elem(grpc_exec_ctx *exec_ctx,
 
 static void server_init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  const void *server_transport_data,
-                                  grpc_transport_stream_op *initial_op) {
+                                  grpc_call_element_args *args) {
   call_data *d = elem->call_data;
   GPR_ASSERT(d != NULL);
   memset(d, 0, sizeof(*d));
   d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
   /* TODO(hongyu): call census_tracing_start_op here. */
-  grpc_closure_init(d->on_done_recv, server_on_done_recv, elem);
-  if (initial_op) server_mutate_op(elem, initial_op);
+  grpc_closure_init(&d->finish_recv, server_on_done_recv, elem);
 }
 
 static void server_destroy_call_elem(grpc_exec_ctx *exec_ctx,
@@ -165,33 +159,26 @@ static void server_destroy_call_elem(grpc_exec_ctx *exec_ctx,
 }
 
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
   channel_data *chand = elem->channel_data;
   GPR_ASSERT(chand != NULL);
-  chand->path_str = grpc_mdstr_from_string(mdctx, ":path");
 }
 
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {
   channel_data *chand = elem->channel_data;
   GPR_ASSERT(chand != NULL);
-  if (chand->path_str != NULL) {
-    GRPC_MDSTR_UNREF(chand->path_str);
-  }
 }
 
 const grpc_channel_filter grpc_client_census_filter = {
-    client_start_transport_op, grpc_channel_next_op,
-    sizeof(call_data),         client_init_call_elem,
-    client_destroy_call_elem,  sizeof(channel_data),
-    init_channel_elem,         destroy_channel_elem,
-    grpc_call_next_get_peer,   "census-client"};
+    client_start_transport_op, grpc_channel_next_op, sizeof(call_data),
+    client_init_call_elem, grpc_call_stack_ignore_set_pollset,
+    client_destroy_call_elem, sizeof(channel_data), init_channel_elem,
+    destroy_channel_elem, grpc_call_next_get_peer, "census-client"};
 
 const grpc_channel_filter grpc_server_census_filter = {
-    server_start_transport_op, grpc_channel_next_op,
-    sizeof(call_data),         server_init_call_elem,
-    server_destroy_call_elem,  sizeof(channel_data),
-    init_channel_elem,         destroy_channel_elem,
-    grpc_call_next_get_peer,   "census-server"};
+    server_start_transport_op, grpc_channel_next_op, sizeof(call_data),
+    server_init_call_elem, grpc_call_stack_ignore_set_pollset,
+    server_destroy_call_elem, sizeof(channel_data), init_channel_elem,
+    destroy_channel_elem, grpc_call_next_get_peer, "census-server"};

src/core/channel/channel_stack.c

@@ -104,13 +104,13 @@ grpc_call_element *grpc_call_stack_element(grpc_call_stack *call_stack,
 void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx,
                              const grpc_channel_filter **filters,
                              size_t filter_count, grpc_channel *master,
-                             const grpc_channel_args *args,
-                             grpc_mdctx *metadata_context,
+                             const grpc_channel_args *channel_args,
                              grpc_channel_stack *stack) {
   size_t call_size =
       ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(grpc_call_stack)) +
       ROUND_UP_TO_ALIGNMENT_SIZE(filter_count * sizeof(grpc_call_element));
   grpc_channel_element *elems;
+  grpc_channel_element_args args;
   char *user_data;
   size_t i;
 
@@ -122,11 +122,13 @@ void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx,
 
   /* init per-filter data */
   for (i = 0; i < filter_count; i++) {
+    args.master = master;
+    args.channel_args = channel_args;
+    args.is_first = i == 0;
+    args.is_last = i == (filter_count - 1);
     elems[i].filter = filters[i];
     elems[i].channel_data = user_data;
-    elems[i].filter->init_channel_elem(exec_ctx, &elems[i], master, args,
-                                       metadata_context, i == 0,
-                                       i == (filter_count - 1));
+    elems[i].filter->init_channel_elem(exec_ctx, &elems[i], &args);
     user_data += ROUND_UP_TO_ALIGNMENT_SIZE(filters[i]->sizeof_channel_data);
     call_size += ROUND_UP_TO_ALIGNMENT_SIZE(filters[i]->sizeof_call_data);
   }
@@ -151,33 +153,63 @@ void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
 }
 
 void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
-                          grpc_channel_stack *channel_stack,
+                          grpc_channel_stack *channel_stack, int initial_refs,
+                          grpc_iomgr_cb_func destroy, void *destroy_arg,
+                          grpc_call_context_element *context,
                           const void *transport_server_data,
-                          grpc_transport_stream_op *initial_op,
                           grpc_call_stack *call_stack) {
   grpc_channel_element *channel_elems = CHANNEL_ELEMS_FROM_STACK(channel_stack);
+  grpc_call_element_args args;
   size_t count = channel_stack->count;
   grpc_call_element *call_elems;
   char *user_data;
   size_t i;
 
   call_stack->count = count;
+  gpr_ref_init(&call_stack->refcount.refs, initial_refs);
+  grpc_closure_init(&call_stack->refcount.destroy, destroy, destroy_arg);
   call_elems = CALL_ELEMS_FROM_STACK(call_stack);
   user_data = ((char *)call_elems) +
               ROUND_UP_TO_ALIGNMENT_SIZE(count * sizeof(grpc_call_element));
 
   /* init per-filter data */
   for (i = 0; i < count; i++) {
+    args.refcount = &call_stack->refcount;
+    args.server_transport_data = transport_server_data;
+    args.context = context;
     call_elems[i].filter = channel_elems[i].filter;
     call_elems[i].channel_data = channel_elems[i].channel_data;
     call_elems[i].call_data = user_data;
-    call_elems[i].filter->init_call_elem(exec_ctx, &call_elems[i],
-                                         transport_server_data, initial_op);
+    call_elems[i].filter->init_call_elem(exec_ctx, &call_elems[i], &args);
     user_data +=
         ROUND_UP_TO_ALIGNMENT_SIZE(call_elems[i].filter->sizeof_call_data);
   }
 }
 
+void grpc_call_stack_set_pollset(grpc_exec_ctx *exec_ctx,
+                                 grpc_call_stack *call_stack,
+                                 grpc_pollset *pollset) {
+  size_t count = call_stack->count;
+  grpc_call_element *call_elems;
+  char *user_data;
+  size_t i;
+
+  call_elems = CALL_ELEMS_FROM_STACK(call_stack);
+  user_data = ((char *)call_elems) +
+              ROUND_UP_TO_ALIGNMENT_SIZE(count * sizeof(grpc_call_element));
+
+  /* init per-filter data */
+  for (i = 0; i < count; i++) {
+    call_elems[i].filter->set_pollset(exec_ctx, &call_elems[i], pollset);
+    user_data +=
+        ROUND_UP_TO_ALIGNMENT_SIZE(call_elems[i].filter->sizeof_call_data);
+  }
+}
+
+void grpc_call_stack_ignore_set_pollset(grpc_exec_ctx *exec_ctx,
+                                        grpc_call_element *elem,
+                                        grpc_pollset *pollset) {}
+
 void grpc_call_stack_destroy(grpc_exec_ctx *exec_ctx, grpc_call_stack *stack) {
   grpc_call_element *elems = CALL_ELEMS_FROM_STACK(stack);
   size_t count = stack->count;

src/core/channel/channel_stack.h

@@ -51,6 +51,19 @@
 typedef struct grpc_channel_element grpc_channel_element;
 typedef struct grpc_call_element grpc_call_element;
 
+typedef struct {
+  grpc_channel *master;
+  const grpc_channel_args *channel_args;
+  int is_first;
+  int is_last;
+} grpc_channel_element_args;
+
+typedef struct {
+  grpc_stream_refcount *refcount;
+  const void *server_transport_data;
+  grpc_call_context_element *context;
+} grpc_call_element_args;
+
 /* Channel filters specify:
    1. the amount of memory needed in the channel & call (via the sizeof_XXX
       members)
@@ -84,8 +97,9 @@ typedef struct {
      transport and is on the server. Most filters want to ignore this
      argument. */
   void (*init_call_elem)(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                         const void *server_transport_data,
-                         grpc_transport_stream_op *initial_op);
+                         grpc_call_element_args *args);
+  void (*set_pollset)(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                      grpc_pollset *pollset);
   /* Destroy per call data.
      The filter does not need to do any chaining */
   void (*destroy_call_elem)(grpc_exec_ctx *exec_ctx, grpc_call_element *elem);
@@ -99,9 +113,7 @@ typedef struct {
      useful for asserting correct configuration by upper layer code.
      The filter does not need to do any chaining */
   void (*init_channel_elem)(grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
-                            grpc_channel *master, const grpc_channel_args *args,
-                            grpc_mdctx *metadata_context, int is_first,
-                            int is_last);
+                            grpc_channel_element_args *args);
   /* Destroy per channel data.
      The filter does not need to do any chaining */
   void (*destroy_channel_elem)(grpc_exec_ctx *exec_ctx,
@@ -141,7 +153,14 @@ typedef struct {
 
 /* A call stack tracks a set of related filters for one call, and guarantees
    they live within a single malloc() allocation */
-typedef struct { size_t count; } grpc_call_stack;
+typedef struct {
+  /* shared refcount for this channel stack.
+     MUST be the first element: the underlying code calls destroy
+     with the address of the refcount, but higher layers prefer to think
+     about the address of the call stack itself. */
+  grpc_stream_refcount refcount;
+  size_t count;
+} grpc_call_stack;
 
 /* Get a channel element given a channel stack and its index */
 grpc_channel_element *grpc_channel_stack_element(grpc_channel_stack *stack,
@@ -160,7 +179,6 @@ void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx,
                              const grpc_channel_filter **filters,
                              size_t filter_count, grpc_channel *master,
                              const grpc_channel_args *args,
-                             grpc_mdctx *metadata_context,
                              grpc_channel_stack *stack);
 /* Destroy a channel stack */
 void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
@@ -170,13 +188,35 @@ void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
    expected to be NULL on a client, or an opaque transport owned pointer on the
    server. */
 void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
-                          grpc_channel_stack *channel_stack,
+                          grpc_channel_stack *channel_stack, int initial_refs,
+                          grpc_iomgr_cb_func destroy, void *destroy_arg,
+                          grpc_call_context_element *context,
                           const void *transport_server_data,
-                          grpc_transport_stream_op *initial_op,
                           grpc_call_stack *call_stack);
+/* Set a pollset for a call stack: must occur before the first op is started */
+void grpc_call_stack_set_pollset(grpc_exec_ctx *exec_ctx,
+                                 grpc_call_stack *call_stack,
+                                 grpc_pollset *pollset);
+
+#ifdef GRPC_STREAM_REFCOUNT_DEBUG
+#define grpc_call_stack_ref(call_stack, reason) \
+  grpc_stream_ref(&(call_stack)->refcount, reason)
+#define grpc_call_stack_unref(exec_ctx, call_stack, reason) \
+  grpc_stream_unref(exec_ctx, &(call_stack)->refcount, reason)
+#else
+#define grpc_call_stack_ref(call_stack) grpc_stream_ref(&(call_stack)->refcount)
+#define grpc_call_stack_unref(exec_ctx, call_stack) \
+  grpc_stream_unref(exec_ctx, &(call_stack)->refcount)
+#endif
+
 /* Destroy a call stack */
 void grpc_call_stack_destroy(grpc_exec_ctx *exec_ctx, grpc_call_stack *stack);
 
+/* Ignore set pollset - used by filters to implement the set_pollset method
+   if they don't care about pollsets at all. Does nothing. */
+void grpc_call_stack_ignore_set_pollset(grpc_exec_ctx *exec_ctx,
+                                        grpc_call_element *elem,
+                                        grpc_pollset *pollset);
 /* Call the next operation in a call stack */
 void grpc_call_next_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                        grpc_transport_stream_op *op);

src/core/channel/client_channel.c

@@ -43,6 +43,7 @@
 
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/connected_channel.h"
+#include "src/core/channel/subchannel_call_holder.h"
 #include "src/core/iomgr/iomgr.h"
 #include "src/core/profiling/timers.h"
 #include "src/core/support/string.h"
@@ -51,11 +52,9 @@
 
 /* Client channel implementation */
 
-typedef struct call_data call_data;
+typedef grpc_subchannel_call_holder call_data;
 
 typedef struct client_channel_channel_data {
-  /** metadata context for this channel */
-  grpc_mdctx *mdctx;
   /** resolver for this channel */
   grpc_resolver *resolver;
   /** have we started resolving this channel */
@@ -98,360 +97,22 @@ typedef struct {
   grpc_lb_policy *lb_policy;
 } lb_policy_connectivity_watcher;
 
-typedef enum {
-  CALL_CREATED,
-  CALL_WAITING_FOR_SEND,
-  CALL_WAITING_FOR_CONFIG,
-  CALL_WAITING_FOR_PICK,
-  CALL_WAITING_FOR_CALL,
-  CALL_ACTIVE,
-  CALL_CANCELLED
-} call_state;
-
-struct call_data {
-  /* owning element */
-  grpc_call_element *elem;
-
-  gpr_mu mu_state;
-
-  call_state state;
-  gpr_timespec deadline;
-  grpc_subchannel *picked_channel;
-  grpc_closure async_setup_task;
-  grpc_transport_stream_op waiting_op;
-  /* our child call stack */
-  grpc_subchannel_call *subchannel_call;
-  grpc_linked_mdelem status;
-  grpc_linked_mdelem details;
-};
-
-static grpc_closure *merge_into_waiting_op(grpc_call_element *elem,
-                                           grpc_transport_stream_op *new_op)
-    GRPC_MUST_USE_RESULT;
-
-static void handle_op_after_cancellation(grpc_exec_ctx *exec_ctx,
-                                         grpc_call_element *elem,
-                                         grpc_transport_stream_op *op) {
-  call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  if (op->send_ops) {
-    grpc_stream_ops_unref_owned_objects(op->send_ops->ops, op->send_ops->nops);
-    op->on_done_send->cb(exec_ctx, op->on_done_send->cb_arg, 0);
-  }
-  if (op->recv_ops) {
-    char status[GPR_LTOA_MIN_BUFSIZE];
-    grpc_metadata_batch mdb;
-    gpr_ltoa(GRPC_STATUS_CANCELLED, status);
-    calld->status.md =
-        grpc_mdelem_from_strings(chand->mdctx, "grpc-status", status);
-    calld->details.md =
-        grpc_mdelem_from_strings(chand->mdctx, "grpc-message", "Cancelled");
-    calld->status.prev = calld->details.next = NULL;
-    calld->status.next = &calld->details;
-    calld->details.prev = &calld->status;
-    mdb.list.head = &calld->status;
-    mdb.list.tail = &calld->details;
-    mdb.garbage.head = mdb.garbage.tail = NULL;
-    mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
-    grpc_sopb_add_metadata(op->recv_ops, mdb);
-    *op->recv_state = GRPC_STREAM_CLOSED;
-    op->on_done_recv->cb(exec_ctx, op->on_done_recv->cb_arg, 1);
-  }
-  if (op->on_consumed) {
-    op->on_consumed->cb(exec_ctx, op->on_consumed->cb_arg, 0);
-  }
-}
-
 typedef struct {
   grpc_closure closure;
   grpc_call_element *elem;
 } waiting_call;
 
-static void perform_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                        grpc_call_element *elem,
-                                        grpc_transport_stream_op *op,
-                                        int continuation);
-
-static void continue_with_pick(grpc_exec_ctx *exec_ctx, void *arg,
-                               int iomgr_success) {
-  waiting_call *wc = arg;
-  call_data *calld = wc->elem->call_data;
-  perform_transport_stream_op(exec_ctx, wc->elem, &calld->waiting_op, 1);
-  gpr_free(wc);
-}
-
-static void add_to_lb_policy_wait_queue_locked_state_config(
-    grpc_call_element *elem) {
-  channel_data *chand = elem->channel_data;
-  waiting_call *wc = gpr_malloc(sizeof(*wc));
-  grpc_closure_init(&wc->closure, continue_with_pick, wc);
-  wc->elem = elem;
-  grpc_closure_list_add(&chand->waiting_for_config_closures, &wc->closure, 1);
-}
-
-static int is_empty(void *p, int len) {
-  char *ptr = p;
-  int i;
-  for (i = 0; i < len; i++) {
-    if (ptr[i] != 0) return 0;
-  }
-  return 1;
-}
-
-static void started_call_locked(grpc_exec_ctx *exec_ctx, void *arg,
-                                int iomgr_success) {
-  call_data *calld = arg;
-  grpc_transport_stream_op op;
-  int have_waiting;
-
-  if (calld->state == CALL_CANCELLED && calld->subchannel_call != NULL) {
-    memset(&op, 0, sizeof(op));
-    op.cancel_with_status = GRPC_STATUS_CANCELLED;
-    gpr_mu_unlock(&calld->mu_state);
-    grpc_subchannel_call_process_op(exec_ctx, calld->subchannel_call, &op);
-  } else if (calld->state == CALL_WAITING_FOR_CALL) {
-    have_waiting = !is_empty(&calld->waiting_op, sizeof(calld->waiting_op));
-    if (calld->subchannel_call != NULL) {
-      calld->state = CALL_ACTIVE;
-      gpr_mu_unlock(&calld->mu_state);
-      if (have_waiting) {
-        grpc_subchannel_call_process_op(exec_ctx, calld->subchannel_call,
-                                        &calld->waiting_op);
-      }
-    } else {
-      calld->state = CALL_CANCELLED;
-      gpr_mu_unlock(&calld->mu_state);
-      if (have_waiting) {
-        handle_op_after_cancellation(exec_ctx, calld->elem, &calld->waiting_op);
-      }
-    }
-  } else {
-    GPR_ASSERT(calld->state == CALL_CANCELLED);
-    gpr_mu_unlock(&calld->mu_state);
-  }
-}
-
-static void started_call(grpc_exec_ctx *exec_ctx, void *arg,
-                         int iomgr_success) {
-  call_data *calld = arg;
-  gpr_mu_lock(&calld->mu_state);
-  started_call_locked(exec_ctx, arg, iomgr_success);
-}
-
-static void picked_target(grpc_exec_ctx *exec_ctx, void *arg,
-                          int iomgr_success) {
-  call_data *calld = arg;
-  grpc_pollset *pollset;
-  grpc_subchannel_call_create_status call_creation_status;
-
-  GPR_TIMER_BEGIN("picked_target", 0);
-
-  if (calld->picked_channel == NULL) {
-    /* treat this like a cancellation */
-    calld->waiting_op.cancel_with_status = GRPC_STATUS_UNAVAILABLE;
-    perform_transport_stream_op(exec_ctx, calld->elem, &calld->waiting_op, 1);
-  } else {
-    gpr_mu_lock(&calld->mu_state);
-    if (calld->state == CALL_CANCELLED) {
-      gpr_mu_unlock(&calld->mu_state);
-      handle_op_after_cancellation(exec_ctx, calld->elem, &calld->waiting_op);
-    } else {
-      GPR_ASSERT(calld->state == CALL_WAITING_FOR_PICK);
-      calld->state = CALL_WAITING_FOR_CALL;
-      pollset = calld->waiting_op.bind_pollset;
-      grpc_closure_init(&calld->async_setup_task, started_call, calld);
-      call_creation_status = grpc_subchannel_create_call(
-          exec_ctx, calld->picked_channel, pollset, &calld->subchannel_call,
-          &calld->async_setup_task);
-      if (call_creation_status == GRPC_SUBCHANNEL_CALL_CREATE_READY) {
-        started_call_locked(exec_ctx, calld, iomgr_success);
-      } else {
-        gpr_mu_unlock(&calld->mu_state);
-      }
-    }
-  }
-
-  GPR_TIMER_END("picked_target", 0);
-}
-
-static grpc_closure *merge_into_waiting_op(grpc_call_element *elem,
-                                           grpc_transport_stream_op *new_op) {
-  call_data *calld = elem->call_data;
-  grpc_closure *consumed_op = NULL;
-  grpc_transport_stream_op *waiting_op = &calld->waiting_op;
-  GPR_ASSERT((waiting_op->send_ops != NULL) + (new_op->send_ops != NULL) <= 1);
-  GPR_ASSERT((waiting_op->recv_ops != NULL) + (new_op->recv_ops != NULL) <= 1);
-  if (new_op->send_ops != NULL) {
-    waiting_op->send_ops = new_op->send_ops;
-    waiting_op->is_last_send = new_op->is_last_send;
-    waiting_op->on_done_send = new_op->on_done_send;
-  }
-  if (new_op->recv_ops != NULL) {
-    waiting_op->recv_ops = new_op->recv_ops;
-    waiting_op->recv_state = new_op->recv_state;
-    waiting_op->on_done_recv = new_op->on_done_recv;
-  }
-  if (new_op->on_consumed != NULL) {
-    if (waiting_op->on_consumed != NULL) {
-      consumed_op = waiting_op->on_consumed;
-    }
-    waiting_op->on_consumed = new_op->on_consumed;
-  }
-  if (new_op->cancel_with_status != GRPC_STATUS_OK) {
-    waiting_op->cancel_with_status = new_op->cancel_with_status;
-  }
-  return consumed_op;
-}
-
 static char *cc_get_peer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
-  call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  grpc_subchannel_call *subchannel_call;
-  char *result;
-
-  gpr_mu_lock(&calld->mu_state);
-  if (calld->state == CALL_ACTIVE) {
-    subchannel_call = calld->subchannel_call;
-    GRPC_SUBCHANNEL_CALL_REF(subchannel_call, "get_peer");
-    gpr_mu_unlock(&calld->mu_state);
-    result = grpc_subchannel_call_get_peer(exec_ctx, subchannel_call);
-    GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, subchannel_call, "get_peer");
-    return result;
-  } else {
-    gpr_mu_unlock(&calld->mu_state);
-    return grpc_channel_get_target(chand->master);
-  }
-}
-
-static void perform_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                        grpc_call_element *elem,
-                                        grpc_transport_stream_op *op,
-                                        int continuation) {
-  call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  grpc_subchannel_call *subchannel_call;
-  grpc_lb_policy *lb_policy;
-  grpc_transport_stream_op op2;
-  GPR_TIMER_BEGIN("perform_transport_stream_op", 0);
-  GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
-  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
-
-  gpr_mu_lock(&calld->mu_state);
-  switch (calld->state) {
-    case CALL_ACTIVE:
-      GPR_ASSERT(!continuation);
-      subchannel_call = calld->subchannel_call;
-      gpr_mu_unlock(&calld->mu_state);
-      grpc_subchannel_call_process_op(exec_ctx, subchannel_call, op);
-      break;
-    case CALL_CANCELLED:
-      gpr_mu_unlock(&calld->mu_state);
-      handle_op_after_cancellation(exec_ctx, elem, op);
-      break;
-    case CALL_WAITING_FOR_SEND:
-      GPR_ASSERT(!continuation);
-      grpc_exec_ctx_enqueue(exec_ctx, merge_into_waiting_op(elem, op), 1);
-      if (!calld->waiting_op.send_ops &&
-          calld->waiting_op.cancel_with_status == GRPC_STATUS_OK) {
-        gpr_mu_unlock(&calld->mu_state);
-        break;
-      }
-      *op = calld->waiting_op;
-      memset(&calld->waiting_op, 0, sizeof(calld->waiting_op));
-      continuation = 1;
-    /* fall through */
-    case CALL_WAITING_FOR_CONFIG:
-    case CALL_WAITING_FOR_PICK:
-    case CALL_WAITING_FOR_CALL:
-      if (!continuation) {
-        if (op->cancel_with_status != GRPC_STATUS_OK) {
-          calld->state = CALL_CANCELLED;
-          op2 = calld->waiting_op;
-          memset(&calld->waiting_op, 0, sizeof(calld->waiting_op));
-          if (op->on_consumed) {
-            calld->waiting_op.on_consumed = op->on_consumed;
-            op->on_consumed = NULL;
-          } else if (op2.on_consumed) {
-            calld->waiting_op.on_consumed = op2.on_consumed;
-            op2.on_consumed = NULL;
-          }
-          gpr_mu_unlock(&calld->mu_state);
-          handle_op_after_cancellation(exec_ctx, elem, op);
-          handle_op_after_cancellation(exec_ctx, elem, &op2);
-        } else {
-          grpc_exec_ctx_enqueue(exec_ctx, merge_into_waiting_op(elem, op), 1);
-          gpr_mu_unlock(&calld->mu_state);
-        }
-        break;
-      }
-    /* fall through */
-    case CALL_CREATED:
-      if (op->cancel_with_status != GRPC_STATUS_OK) {
-        calld->state = CALL_CANCELLED;
-        gpr_mu_unlock(&calld->mu_state);
-        handle_op_after_cancellation(exec_ctx, elem, op);
-      } else {
-        calld->waiting_op = *op;
-
-        if (op->send_ops == NULL) {
-          /* need to have some send ops before we can select the
-             lb target */
-          calld->state = CALL_WAITING_FOR_SEND;
-          gpr_mu_unlock(&calld->mu_state);
-        } else {
-          gpr_mu_lock(&chand->mu_config);
-          lb_policy = chand->lb_policy;
-          if (lb_policy) {
-            grpc_transport_stream_op *waiting_op = &calld->waiting_op;
-            grpc_pollset *bind_pollset = waiting_op->bind_pollset;
-            grpc_metadata_batch *initial_metadata =
-                &waiting_op->send_ops->ops[0].data.metadata;
-            GRPC_LB_POLICY_REF(lb_policy, "pick");
-            gpr_mu_unlock(&chand->mu_config);
-            calld->state = CALL_WAITING_FOR_PICK;
-
-            GPR_ASSERT(waiting_op->bind_pollset);
-            GPR_ASSERT(waiting_op->send_ops);
-            GPR_ASSERT(waiting_op->send_ops->nops >= 1);
-            GPR_ASSERT(waiting_op->send_ops->ops[0].type == GRPC_OP_METADATA);
-            gpr_mu_unlock(&calld->mu_state);
-
-            grpc_closure_init(&calld->async_setup_task, picked_target, calld);
-            grpc_lb_policy_pick(exec_ctx, lb_policy, bind_pollset,
-                                initial_metadata, &calld->picked_channel,
-                                &calld->async_setup_task);
-
-            GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "pick");
-          } else if (chand->resolver != NULL) {
-            calld->state = CALL_WAITING_FOR_CONFIG;
-            add_to_lb_policy_wait_queue_locked_state_config(elem);
-            if (!chand->started_resolving && chand->resolver != NULL) {
-              GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
-              chand->started_resolving = 1;
-              grpc_resolver_next(exec_ctx, chand->resolver,
-                                 &chand->incoming_configuration,
-                                 &chand->on_config_changed);
-            }
-            gpr_mu_unlock(&chand->mu_config);
-            gpr_mu_unlock(&calld->mu_state);
-          } else {
-            calld->state = CALL_CANCELLED;
-            gpr_mu_unlock(&chand->mu_config);
-            gpr_mu_unlock(&calld->mu_state);
-            handle_op_after_cancellation(exec_ctx, elem, op);
-          }
-        }
-      }
-      break;
-  }
-
-  GPR_TIMER_END("perform_transport_stream_op", 0);
+  return grpc_subchannel_call_holder_get_peer(exec_ctx, elem->call_data,
+                                              chand->master);
 }
 
 static void cc_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
                                          grpc_call_element *elem,
                                          grpc_transport_stream_op *op) {
-  perform_transport_stream_op(exec_ctx, elem, op, 0);
+  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
+  grpc_subchannel_call_holder_perform_op(exec_ctx, elem->call_data, op);
 }
 
 static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
@@ -593,11 +254,9 @@ static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
     op->connectivity_state = NULL;
   }
 
-  if (!is_empty(op, sizeof(*op))) {
-    lb_policy = chand->lb_policy;
-    if (lb_policy) {
-      GRPC_LB_POLICY_REF(lb_policy, "broadcast");
-    }
+  lb_policy = chand->lb_policy;
+  if (lb_policy) {
+    GRPC_LB_POLICY_REF(lb_policy, "broadcast");
   }
 
   if (op->disconnect && chand->resolver != NULL) {
@@ -624,67 +283,109 @@ static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
   }
 }
 
-/* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+typedef struct {
+  grpc_metadata_batch *initial_metadata;
+  grpc_subchannel **subchannel;
+  grpc_closure *on_ready;
+  grpc_call_element *elem;
+  grpc_closure closure;
+} continue_picking_args;
+
+static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *arg,
+                              grpc_metadata_batch *initial_metadata,
+                              grpc_subchannel **subchannel,
+                              grpc_closure *on_ready);
+
+static void continue_picking(grpc_exec_ctx *exec_ctx, void *arg, int success) {
+  continue_picking_args *cpa = arg;
+  if (!success) {
+    grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, 0);
+  } else if (cpa->subchannel == NULL) {
+    /* cancelled, do nothing */
+  } else if (cc_pick_subchannel(exec_ctx, cpa->elem, cpa->initial_metadata,
+                                cpa->subchannel, cpa->on_ready)) {
+    grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, 1);
+  }
+  gpr_free(cpa);
+}
+
+static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *elemp,
+                              grpc_metadata_batch *initial_metadata,
+                              grpc_subchannel **subchannel,
+                              grpc_closure *on_ready) {
+  grpc_call_element *elem = elemp;
+  channel_data *chand = elem->channel_data;
   call_data *calld = elem->call_data;
+  continue_picking_args *cpa;
+  grpc_closure *closure;
 
-  /* TODO(ctiller): is there something useful we can do here? */
-  GPR_ASSERT(initial_op == NULL);
+  GPR_ASSERT(subchannel);
 
-  GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
-  GPR_ASSERT(server_transport_data == NULL);
-  gpr_mu_init(&calld->mu_state);
-  calld->elem = elem;
-  calld->state = CALL_CREATED;
-  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
+  gpr_mu_lock(&chand->mu_config);
+  if (initial_metadata == NULL) {
+    if (chand->lb_policy != NULL) {
+      grpc_lb_policy_cancel_pick(exec_ctx, chand->lb_policy, subchannel);
+    }
+    for (closure = chand->waiting_for_config_closures.head; closure != NULL;
+         closure = grpc_closure_next(closure)) {
+      cpa = closure->cb_arg;
+      if (cpa->subchannel == subchannel) {
+        cpa->subchannel = NULL;
+        grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, 0);
+      }
+    }
+    gpr_mu_unlock(&chand->mu_config);
+    return 1;
+  }
+  if (chand->lb_policy != NULL) {
+    int r = grpc_lb_policy_pick(exec_ctx, chand->lb_policy, calld->pollset,
+                                initial_metadata, subchannel, on_ready);
+    gpr_mu_unlock(&chand->mu_config);
+    return r;
+  }
+  if (chand->resolver != NULL && !chand->started_resolving) {
+    chand->started_resolving = 1;
+    GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
+    grpc_resolver_next(exec_ctx, chand->resolver,
+                       &chand->incoming_configuration,
+                       &chand->on_config_changed);
+  }
+  cpa = gpr_malloc(sizeof(*cpa));
+  cpa->initial_metadata = initial_metadata;
+  cpa->subchannel = subchannel;
+  cpa->on_ready = on_ready;
+  cpa->elem = elem;
+  grpc_closure_init(&cpa->closure, continue_picking, cpa);
+  grpc_closure_list_add(&chand->waiting_for_config_closures, &cpa->closure, 1);
+  gpr_mu_unlock(&chand->mu_config);
+  return 0;
+}
+
+/* Constructor for call_data */
+static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                           grpc_call_element_args *args) {
+  grpc_subchannel_call_holder_init(elem->call_data, cc_pick_subchannel, elem);
 }
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
                               grpc_call_element *elem) {
-  call_data *calld = elem->call_data;
-  grpc_subchannel_call *subchannel_call;
-
-  /* if the call got activated, we need to destroy the child stack also, and
-     remove it from the in-flight requests tracked by the child_entry we
-     picked */
-  gpr_mu_lock(&calld->mu_state);
-  switch (calld->state) {
-    case CALL_ACTIVE:
-      subchannel_call = calld->subchannel_call;
-      gpr_mu_unlock(&calld->mu_state);
-      GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, subchannel_call, "client_channel");
-      break;
-    case CALL_CREATED:
-    case CALL_CANCELLED:
-      gpr_mu_unlock(&calld->mu_state);
-      break;
-    case CALL_WAITING_FOR_PICK:
-    case CALL_WAITING_FOR_CONFIG:
-    case CALL_WAITING_FOR_CALL:
-    case CALL_WAITING_FOR_SEND:
-      GPR_UNREACHABLE_CODE(return );
-  }
+  grpc_subchannel_call_holder_destroy(exec_ctx, elem->call_data);
 }
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args,
-                              grpc_mdctx *metadata_context, int is_first,
-                              int is_last) {
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
   channel_data *chand = elem->channel_data;
 
   memset(chand, 0, sizeof(*chand));
 
-  GPR_ASSERT(is_last);
+  GPR_ASSERT(args->is_last);
   GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
 
   gpr_mu_init(&chand->mu_config);
-  chand->mdctx = metadata_context;
-  chand->master = master;
+  chand->master = args->master;
   grpc_pollset_set_init(&chand->pollset_set);
   grpc_closure_init(&chand->on_config_changed, cc_on_config_changed, chand);
 
@@ -709,10 +410,16 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   gpr_mu_destroy(&chand->mu_config);
 }
 
+static void cc_set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                           grpc_pollset *pollset) {
+  call_data *calld = elem->call_data;
+  calld->pollset = pollset;
+}
+
 const grpc_channel_filter grpc_client_channel_filter = {
     cc_start_transport_stream_op, cc_start_transport_op, sizeof(call_data),
-    init_call_elem, destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, cc_get_peer, "client-channel",
+    init_call_elem, cc_set_pollset, destroy_call_elem, sizeof(channel_data),
+    init_channel_elem, destroy_channel_elem, cc_get_peer, "client-channel",
 };
 
 void grpc_client_channel_set_resolver(grpc_exec_ctx *exec_ctx,

src/core/channel/client_uchannel.c

@@ -39,6 +39,7 @@
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
 #include "src/core/channel/compress_filter.h"
+#include "src/core/channel/subchannel_call_holder.h"
 #include "src/core/iomgr/iomgr.h"
 #include "src/core/support/string.h"
 #include "src/core/surface/channel.h"
@@ -52,12 +53,7 @@
 /** Microchannel (uchannel) implementation: a lightweight channel without any
  * load-balancing mechanisms meant for communication from within the core. */
 
-typedef struct call_data call_data;
-
 typedef struct client_uchannel_channel_data {
-  /** metadata context for this channel */
-  grpc_mdctx *mdctx;
-
   /** master channel - the grpc_channel instance that ultimately owns
       this channel_data via its channel stack.
       We occasionally use this to bump the refcount on the master channel
@@ -80,85 +76,7 @@ typedef struct client_uchannel_channel_data {
   gpr_mu mu_state;
 } channel_data;
 
-typedef enum {
-  CALL_CREATED,
-  CALL_WAITING_FOR_SEND,
-  CALL_WAITING_FOR_CALL,
-  CALL_ACTIVE,
-  CALL_CANCELLED
-} call_state;
-
-struct call_data {
-  /* owning element */
-  grpc_call_element *elem;
-
-  gpr_mu mu_state;
-
-  call_state state;
-  gpr_timespec deadline;
-  grpc_closure async_setup_task;
-  grpc_transport_stream_op waiting_op;
-  /* our child call stack */
-  grpc_subchannel_call *subchannel_call;
-  grpc_linked_mdelem status;
-  grpc_linked_mdelem details;
-};
-
-static grpc_closure *merge_into_waiting_op(grpc_call_element *elem,
-                                           grpc_transport_stream_op *new_op)
-    GRPC_MUST_USE_RESULT;
-
-static void handle_op_after_cancellation(grpc_exec_ctx *exec_ctx,
-                                         grpc_call_element *elem,
-                                         grpc_transport_stream_op *op) {
-  call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  if (op->send_ops) {
-    grpc_stream_ops_unref_owned_objects(op->send_ops->ops, op->send_ops->nops);
-    op->on_done_send->cb(exec_ctx, op->on_done_send->cb_arg, 0);
-  }
-  if (op->recv_ops) {
-    char status[GPR_LTOA_MIN_BUFSIZE];
-    grpc_metadata_batch mdb;
-    gpr_ltoa(GRPC_STATUS_CANCELLED, status);
-    calld->status.md =
-        grpc_mdelem_from_strings(chand->mdctx, "grpc-status", status);
-    calld->details.md =
-        grpc_mdelem_from_strings(chand->mdctx, "grpc-message", "Cancelled");
-    calld->status.prev = calld->details.next = NULL;
-    calld->status.next = &calld->details;
-    calld->details.prev = &calld->status;
-    mdb.list.head = &calld->status;
-    mdb.list.tail = &calld->details;
-    mdb.garbage.head = mdb.garbage.tail = NULL;
-    mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
-    grpc_sopb_add_metadata(op->recv_ops, mdb);
-    *op->recv_state = GRPC_STREAM_CLOSED;
-    op->on_done_recv->cb(exec_ctx, op->on_done_recv->cb_arg, 1);
-  }
-  if (op->on_consumed) {
-    op->on_consumed->cb(exec_ctx, op->on_consumed->cb_arg, 0);
-  }
-}
-
-typedef struct {
-  grpc_closure closure;
-  grpc_call_element *elem;
-} waiting_call;
-
-static void perform_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                        grpc_call_element *elem,
-                                        grpc_transport_stream_op *op,
-                                        int continuation);
-
-static int is_empty(void *p, int len) {
-  char *ptr = p;
-  int i;
-  for (i = 0; i < len; i++) {
-    if (ptr[i] != 0) return 0;
-  }
-  return 1;
-}
+typedef grpc_subchannel_call_holder call_data;
 
 static void monitor_subchannel(grpc_exec_ctx *exec_ctx, void *arg,
                                int iomgr_success) {
@@ -171,201 +89,17 @@ static void monitor_subchannel(grpc_exec_ctx *exec_ctx, void *arg,
                                          &chand->connectivity_cb);
 }
 
-static void started_call_locked(grpc_exec_ctx *exec_ctx, void *arg,
-                         int iomgr_success) {
-  call_data *calld = arg;
-  grpc_transport_stream_op op;
-  int have_waiting;
-
-  if (calld->state == CALL_CANCELLED && iomgr_success == 0) {
-    have_waiting = !is_empty(&calld->waiting_op, sizeof(calld->waiting_op));
-    gpr_mu_unlock(&calld->mu_state);
-    if (have_waiting) {
-      handle_op_after_cancellation(exec_ctx, calld->elem, &calld->waiting_op);
-    }
-  } else if (calld->state == CALL_CANCELLED && calld->subchannel_call != NULL) {
-    memset(&op, 0, sizeof(op));
-    op.cancel_with_status = GRPC_STATUS_CANCELLED;
-    gpr_mu_unlock(&calld->mu_state);
-    grpc_subchannel_call_process_op(exec_ctx, calld->subchannel_call, &op);
-  } else if (calld->state == CALL_WAITING_FOR_CALL) {
-    have_waiting = !is_empty(&calld->waiting_op, sizeof(calld->waiting_op));
-    if (calld->subchannel_call != NULL) {
-      calld->state = CALL_ACTIVE;
-      gpr_mu_unlock(&calld->mu_state);
-      if (have_waiting) {
-        grpc_subchannel_call_process_op(exec_ctx, calld->subchannel_call,
-                                        &calld->waiting_op);
-      }
-    } else {
-      calld->state = CALL_CANCELLED;
-      gpr_mu_unlock(&calld->mu_state);
-      if (have_waiting) {
-        handle_op_after_cancellation(exec_ctx, calld->elem, &calld->waiting_op);
-      }
-    }
-  } else {
-    GPR_ASSERT(calld->state == CALL_CANCELLED);
-    gpr_mu_unlock(&calld->mu_state);
-    have_waiting = !is_empty(&calld->waiting_op, sizeof(calld->waiting_op));
-    if (have_waiting) {
-      handle_op_after_cancellation(exec_ctx, calld->elem, &calld->waiting_op);
-    }
-  }
-}
-
-static void started_call(grpc_exec_ctx *exec_ctx, void *arg,
-                         int iomgr_success) {
-  call_data *calld = arg;
-  gpr_mu_lock(&calld->mu_state);
-  started_call_locked(exec_ctx, arg, iomgr_success);
-}
-
-static grpc_closure *merge_into_waiting_op(grpc_call_element *elem,
-                                           grpc_transport_stream_op *new_op) {
-  call_data *calld = elem->call_data;
-  grpc_closure *consumed_op = NULL;
-  grpc_transport_stream_op *waiting_op = &calld->waiting_op;
-  GPR_ASSERT((waiting_op->send_ops != NULL) + (new_op->send_ops != NULL) <= 1);
-  GPR_ASSERT((waiting_op->recv_ops != NULL) + (new_op->recv_ops != NULL) <= 1);
-  if (new_op->send_ops != NULL) {
-    waiting_op->send_ops = new_op->send_ops;
-    waiting_op->is_last_send = new_op->is_last_send;
-    waiting_op->on_done_send = new_op->on_done_send;
-  }
-  if (new_op->recv_ops != NULL) {
-    waiting_op->recv_ops = new_op->recv_ops;
-    waiting_op->recv_state = new_op->recv_state;
-    waiting_op->on_done_recv = new_op->on_done_recv;
-  }
-  if (new_op->on_consumed != NULL) {
-    if (waiting_op->on_consumed != NULL) {
-      consumed_op = waiting_op->on_consumed;
-    }
-    waiting_op->on_consumed = new_op->on_consumed;
-  }
-  if (new_op->cancel_with_status != GRPC_STATUS_OK) {
-    waiting_op->cancel_with_status = new_op->cancel_with_status;
-  }
-  return consumed_op;
-}
-
 static char *cuc_get_peer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
-  call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  grpc_subchannel_call *subchannel_call;
-  char *result;
-
-  gpr_mu_lock(&calld->mu_state);
-  if (calld->state == CALL_ACTIVE) {
-    subchannel_call = calld->subchannel_call;
-    GRPC_SUBCHANNEL_CALL_REF(subchannel_call, "get_peer");
-    gpr_mu_unlock(&calld->mu_state);
-    result = grpc_subchannel_call_get_peer(exec_ctx, subchannel_call);
-    GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, subchannel_call, "get_peer");
-    return result;
-  } else {
-    gpr_mu_unlock(&calld->mu_state);
-    return grpc_channel_get_target(chand->master);
-  }
-}
-
-static void perform_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                        grpc_call_element *elem,
-                                        grpc_transport_stream_op *op,
-                                        int continuation) {
-  call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  grpc_subchannel_call *subchannel_call;
-  grpc_transport_stream_op op2;
-  GPR_ASSERT(elem->filter == &grpc_client_uchannel_filter);
-  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
-
-  gpr_mu_lock(&calld->mu_state);
-  /* make sure the wrapped subchannel has been set (see
-   * grpc_client_uchannel_set_subchannel) */
-  GPR_ASSERT(chand->subchannel != NULL);
-
-  switch (calld->state) {
-    case CALL_ACTIVE:
-      GPR_ASSERT(!continuation);
-      subchannel_call = calld->subchannel_call;
-      gpr_mu_unlock(&calld->mu_state);
-      grpc_subchannel_call_process_op(exec_ctx, subchannel_call, op);
-      break;
-    case CALL_CANCELLED:
-      gpr_mu_unlock(&calld->mu_state);
-      handle_op_after_cancellation(exec_ctx, elem, op);
-      break;
-    case CALL_WAITING_FOR_SEND:
-      GPR_ASSERT(!continuation);
-      grpc_exec_ctx_enqueue(exec_ctx, merge_into_waiting_op(elem, op), 1);
-      if (!calld->waiting_op.send_ops &&
-          calld->waiting_op.cancel_with_status == GRPC_STATUS_OK) {
-        gpr_mu_unlock(&calld->mu_state);
-        break;
-      }
-      *op = calld->waiting_op;
-      memset(&calld->waiting_op, 0, sizeof(calld->waiting_op));
-      continuation = 1;
-    /* fall through */
-    case CALL_WAITING_FOR_CALL:
-      if (!continuation) {
-        if (op->cancel_with_status != GRPC_STATUS_OK) {
-          calld->state = CALL_CANCELLED;
-          op2 = calld->waiting_op;
-          memset(&calld->waiting_op, 0, sizeof(calld->waiting_op));
-          if (op->on_consumed) {
-            calld->waiting_op.on_consumed = op->on_consumed;
-            op->on_consumed = NULL;
-          } else if (op2.on_consumed) {
-            calld->waiting_op.on_consumed = op2.on_consumed;
-            op2.on_consumed = NULL;
-          }
-          gpr_mu_unlock(&calld->mu_state);
-          handle_op_after_cancellation(exec_ctx, elem, op);
-          handle_op_after_cancellation(exec_ctx, elem, &op2);
-          grpc_subchannel_cancel_waiting_call(exec_ctx, chand->subchannel, 1);
-        } else {
-          grpc_exec_ctx_enqueue(exec_ctx, merge_into_waiting_op(elem, op), 1);
-          gpr_mu_unlock(&calld->mu_state);
-        }
-        break;
-      }
-    /* fall through */
-    case CALL_CREATED:
-      if (op->cancel_with_status != GRPC_STATUS_OK) {
-        calld->state = CALL_CANCELLED;
-        gpr_mu_unlock(&calld->mu_state);
-        handle_op_after_cancellation(exec_ctx, elem, op);
-      } else {
-        calld->waiting_op = *op;
-        if (op->send_ops == NULL) {
-          calld->state = CALL_WAITING_FOR_SEND;
-          gpr_mu_unlock(&calld->mu_state);
-        } else {
-          grpc_subchannel_call_create_status call_creation_status;
-          grpc_pollset *pollset = calld->waiting_op.bind_pollset;
-          calld->state = CALL_WAITING_FOR_CALL;
-          grpc_closure_init(&calld->async_setup_task, started_call, calld);
-          call_creation_status = grpc_subchannel_create_call(
-              exec_ctx, chand->subchannel, pollset, &calld->subchannel_call,
-              &calld->async_setup_task);
-          if (call_creation_status == GRPC_SUBCHANNEL_CALL_CREATE_READY) {
-            started_call_locked(exec_ctx, calld, 1);
-          } else {
-            gpr_mu_unlock(&calld->mu_state);
-          }
-        }
-      }
-      break;
-  }
+  return grpc_subchannel_call_holder_get_peer(exec_ctx, elem->call_data,
+                                              chand->master);
 }
 
 static void cuc_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
                                           grpc_call_element *elem,
                                           grpc_transport_stream_op *op) {
-  perform_transport_stream_op(exec_ctx, elem, op, 0);
+  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
+  grpc_subchannel_call_holder_perform_op(exec_ctx, elem->call_data, op);
 }
 
 static void cuc_start_transport_op(grpc_exec_ctx *exec_ctx,
@@ -392,64 +126,39 @@ static void cuc_start_transport_op(grpc_exec_ctx *exec_ctx,
   }
 }
 
+static int cuc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *arg,
+                               grpc_metadata_batch *initial_metadata,
+                               grpc_subchannel **subchannel,
+                               grpc_closure *on_ready) {
+  channel_data *chand = arg;
+  GPR_ASSERT(initial_metadata != NULL);
+  *subchannel = chand->subchannel;
+  return 1;
+}
+
 /* Constructor for call_data */
 static void cuc_init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                               const void *server_transport_data,
-                               grpc_transport_stream_op *initial_op) {
-  call_data *calld = elem->call_data;
-  memset(calld, 0, sizeof(call_data));
-
-  /* TODO(ctiller): is there something useful we can do here? */
-  GPR_ASSERT(initial_op == NULL);
-
-  GPR_ASSERT(elem->filter == &grpc_client_uchannel_filter);
-  GPR_ASSERT(server_transport_data == NULL);
-  gpr_mu_init(&calld->mu_state);
-  calld->elem = elem;
-  calld->state = CALL_CREATED;
-  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
+                               grpc_call_element_args *args) {
+  grpc_subchannel_call_holder_init(elem->call_data, cuc_pick_subchannel,
+                                   elem->channel_data);
 }
 
 /* Destructor for call_data */
 static void cuc_destroy_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem) {
-  call_data *calld = elem->call_data;
-  grpc_subchannel_call *subchannel_call;
-
-  /* if the call got activated, we need to destroy the child stack also, and
-     remove it from the in-flight requests tracked by the child_entry we
-     picked */
-  gpr_mu_lock(&calld->mu_state);
-  switch (calld->state) {
-    case CALL_ACTIVE:
-      subchannel_call = calld->subchannel_call;
-      gpr_mu_unlock(&calld->mu_state);
-      GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, subchannel_call, "client_uchannel");
-      break;
-    case CALL_CREATED:
-    case CALL_CANCELLED:
-      gpr_mu_unlock(&calld->mu_state);
-      break;
-    case CALL_WAITING_FOR_CALL:
-    case CALL_WAITING_FOR_SEND:
-      GPR_UNREACHABLE_CODE(return );
-  }
+  grpc_subchannel_call_holder_destroy(exec_ctx, elem->call_data);
 }
 
 /* Constructor for channel_data */
 static void cuc_init_channel_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_channel_element *elem,
-                                  grpc_channel *master,
-                                  const grpc_channel_args *args,
-                                  grpc_mdctx *metadata_context, int is_first,
-                                  int is_last) {
+                                  grpc_channel_element_args *args) {
   channel_data *chand = elem->channel_data;
   memset(chand, 0, sizeof(*chand));
   grpc_closure_init(&chand->connectivity_cb, monitor_subchannel, chand);
-  GPR_ASSERT(is_last);
+  GPR_ASSERT(args->is_last);
   GPR_ASSERT(elem->filter == &grpc_client_uchannel_filter);
-  chand->mdctx = metadata_context;
-  chand->master = master;
+  chand->master = args->master;
   grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE,
                                "client_uchannel");
   gpr_mu_init(&chand->mu_state);
@@ -465,17 +174,17 @@ static void cuc_destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   gpr_mu_destroy(&chand->mu_state);
 }
 
+static void cuc_set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                            grpc_pollset *pollset) {
+  call_data *calld = elem->call_data;
+  calld->pollset = pollset;
+}
+
 const grpc_channel_filter grpc_client_uchannel_filter = {
-    cuc_start_transport_stream_op,
-    cuc_start_transport_op,
-    sizeof(call_data),
-    cuc_init_call_elem,
-    cuc_destroy_call_elem,
-    sizeof(channel_data),
-    cuc_init_channel_elem,
-    cuc_destroy_channel_elem,
-    cuc_get_peer,
-    "client-uchannel",
+    cuc_start_transport_stream_op, cuc_start_transport_op, sizeof(call_data),
+    cuc_init_call_elem, cuc_set_pollset, cuc_destroy_call_elem,
+    sizeof(channel_data), cuc_init_channel_elem, cuc_destroy_channel_elem,
+    cuc_get_peer, "client-uchannel",
 };
 
 grpc_connectivity_state grpc_client_uchannel_check_connectivity_state(
@@ -539,13 +248,11 @@ grpc_channel *grpc_client_uchannel_create(grpc_subchannel *subchannel,
   grpc_channel *channel = NULL;
 #define MAX_FILTERS 3
   const grpc_channel_filter *filters[MAX_FILTERS];
-  grpc_mdctx *mdctx = grpc_subchannel_get_mdctx(subchannel);
   grpc_channel *master = grpc_subchannel_get_master(subchannel);
   char *target = grpc_channel_get_target(master);
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   size_t n = 0;
 
-  grpc_mdctx_ref(mdctx);
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
   }
@@ -553,8 +260,8 @@ grpc_channel *grpc_client_uchannel_create(grpc_subchannel *subchannel,
   filters[n++] = &grpc_client_uchannel_filter;
   GPR_ASSERT(n <= MAX_FILTERS);
 
-  channel = grpc_channel_create_from_filters(&exec_ctx, target, filters, n,
-                                             args, mdctx, 1);
+  channel =
+      grpc_channel_create_from_filters(&exec_ctx, target, filters, n, args, 1);
 
   gpr_free(target);
   return channel;

src/core/channel/compress_filter.c

@@ -42,58 +42,41 @@
 #include "src/core/channel/compress_filter.h"
 #include "src/core/channel/channel_args.h"
 #include "src/core/profiling/timers.h"
+#include "src/core/compression/algorithm_metadata.h"
 #include "src/core/compression/message_compress.h"
 #include "src/core/support/string.h"
+#include "src/core/transport/static_metadata.h"
 
 typedef struct call_data {
   gpr_slice_buffer slices; /**< Buffers up input slices to be compressed */
   grpc_linked_mdelem compression_algorithm_storage;
   grpc_linked_mdelem accept_encoding_storage;
   gpr_uint32 remaining_slice_bytes;
-  /**< Input data to be read, as per BEGIN_MESSAGE */
-  int written_initial_metadata; /**< Already processed initial md? */
   /** Compression algorithm we'll try to use. It may be given by incoming
    * metadata, or by the channel's default compression settings. */
   grpc_compression_algorithm compression_algorithm;
   /** If true, contents of \a compression_algorithm are authoritative */
   int has_compression_algorithm;
+
+  grpc_transport_stream_op send_op;
+  gpr_uint32 send_length;
+  gpr_uint32 send_flags;
+  gpr_slice incoming_slice;
+  grpc_slice_buffer_stream replacement_stream;
+  grpc_closure *post_send;
+  grpc_closure send_done;
+  grpc_closure got_slice;
 } call_data;
 
 typedef struct channel_data {
-  /** Metadata key for the incoming (requested) compression algorithm */
-  grpc_mdstr *mdstr_request_compression_algorithm_key;
-  /** Metadata key for the outgoing (used) compression algorithm */
-  grpc_mdstr *mdstr_outgoing_compression_algorithm_key;
-  /** Metadata key for the accepted encodings */
-  grpc_mdstr *mdstr_compression_capabilities_key;
-  /** Precomputed metadata elements for all available compression algorithms */
-  grpc_mdelem *mdelem_compression_algorithms[GRPC_COMPRESS_ALGORITHMS_COUNT];
-  /** Precomputed metadata elements for the accepted encodings */
-  grpc_mdelem *mdelem_accept_encoding;
   /** The default, channel-level, compression algorithm */
   grpc_compression_algorithm default_compression_algorithm;
   /** Compression options for the channel */
   grpc_compression_options compression_options;
+  /** Supported compression algorithms */
+  gpr_uint32 supported_compression_algorithms;
 } channel_data;
 
-/** Compress \a slices in place using \a algorithm. Returns 1 if compression did
- * actually happen, 0 otherwise (for example if the compressed output size was
- * larger than the raw input).
- *
- * Returns 1 if the data was actually compress and 0 otherwise. */
-static int compress_send_sb(grpc_compression_algorithm algorithm,
-                            gpr_slice_buffer *slices) {
-  int did_compress;
-  gpr_slice_buffer tmp;
-  gpr_slice_buffer_init(&tmp);
-  did_compress = grpc_msg_compress(algorithm, slices, &tmp);
-  if (did_compress) {
-    gpr_slice_buffer_swap(slices, &tmp);
-  }
-  gpr_slice_buffer_destroy(&tmp);
-  return did_compress;
-}
-
 /** For each \a md element from the incoming metadata, filter out the entry for
  * "grpc-encoding", using its value to populate the call data's
  * compression_algorithm field. */
@@ -102,7 +85,7 @@ static grpc_mdelem *compression_md_filter(void *user_data, grpc_mdelem *md) {
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
 
-  if (md->key == channeld->mdstr_request_compression_algorithm_key) {
+  if (md->key == GRPC_MDSTR_GRPC_INTERNAL_ENCODING_REQUEST) {
     const char *md_c_str = grpc_mdstr_as_c_string(md->value);
     if (!grpc_compression_algorithm_parse(md_c_str, strlen(md_c_str),
                                           &calld->compression_algorithm)) {
@@ -127,7 +110,9 @@ static grpc_mdelem *compression_md_filter(void *user_data, grpc_mdelem *md) {
   return md;
 }
 
-static int skip_compression(channel_data *channeld, call_data *calld) {
+static int skip_compression(grpc_call_element *elem) {
+  call_data *calld = elem->call_data;
+  channel_data *channeld = elem->channel_data;
   if (calld->has_compression_algorithm) {
     if (calld->compression_algorithm == GRPC_COMPRESS_NONE) {
       return 1;
@@ -138,169 +123,126 @@ static int skip_compression(channel_data *channeld, call_data *calld) {
   return channeld->default_compression_algorithm == GRPC_COMPRESS_NONE;
 }
 
-/** Assembles a new grpc_stream_op_buffer with the compressed slices, modifying
- * the associated GRPC_OP_BEGIN_MESSAGE accordingly (new compressed length,
- * flags indicating compression is in effect) and replaces \a send_ops with it.
- * */
-static void finish_compressed_sopb(grpc_stream_op_buffer *send_ops,
-                                   grpc_call_element *elem) {
-  size_t i;
+/** Filter initial metadata */
+static void process_send_initial_metadata(
+    grpc_call_element *elem, grpc_metadata_batch *initial_metadata) {
   call_data *calld = elem->call_data;
-  int new_slices_added = 0; /* GPR_FALSE */
-  grpc_metadata_batch metadata;
-  grpc_stream_op_buffer new_send_ops;
-  grpc_sopb_init(&new_send_ops);
-
-  for (i = 0; i < send_ops->nops; i++) {
-    grpc_stream_op *sop = &send_ops->ops[i];
-    switch (sop->type) {
-      case GRPC_OP_BEGIN_MESSAGE:
-        GPR_ASSERT(calld->slices.length <= GPR_UINT32_MAX);
-        grpc_sopb_add_begin_message(
-            &new_send_ops, (gpr_uint32)calld->slices.length,
-            sop->data.begin_message.flags | GRPC_WRITE_INTERNAL_COMPRESS);
-        break;
-      case GRPC_OP_SLICE:
-        /* Once we reach the slices section of the original buffer, simply add
-         * all the new (compressed) slices. We obviously want to do this only
-         * once, hence the "new_slices_added" guard. */
-        if (!new_slices_added) {
-          size_t j;
-          for (j = 0; j < calld->slices.count; ++j) {
-            grpc_sopb_add_slice(&new_send_ops,
-                                gpr_slice_ref(calld->slices.slices[j]));
-          }
-          new_slices_added = 1; /* GPR_TRUE */
-        }
-        break;
-      case GRPC_OP_METADATA:
-        /* move the metadata to the new buffer. */
-        grpc_metadata_batch_move(&metadata, &sop->data.metadata);
-        grpc_sopb_add_metadata(&new_send_ops, metadata);
-        break;
-      case GRPC_NO_OP:
-        break;
-    }
+  channel_data *channeld = elem->channel_data;
+  /* Parse incoming request for compression. If any, it'll be available
+   * at calld->compression_algorithm */
+  grpc_metadata_batch_filter(initial_metadata, compression_md_filter, elem);
+  if (!calld->has_compression_algorithm) {
+    /* If no algorithm was found in the metadata and we aren't
+     * exceptionally skipping compression, fall back to the channel
+     * default */
+    calld->compression_algorithm = channeld->default_compression_algorithm;
+    calld->has_compression_algorithm = 1; /* GPR_TRUE */
   }
-  grpc_sopb_swap(send_ops, &new_send_ops);
-  grpc_sopb_destroy(&new_send_ops);
+  /* hint compression algorithm */
+  grpc_metadata_batch_add_tail(
+      initial_metadata, &calld->compression_algorithm_storage,
+      grpc_compression_encoding_mdelem(calld->compression_algorithm));
+
+  /* convey supported compression algorithms */
+  grpc_metadata_batch_add_tail(initial_metadata,
+                               &calld->accept_encoding_storage,
+                               GRPC_MDELEM_ACCEPT_ENCODING_FOR_ALGORITHMS(
+                                   channeld->supported_compression_algorithms));
 }
 
-/** Filter's "main" function, called for any incoming grpc_transport_stream_op
- * instance that holds a non-zero number of send operations, accesible to this
- * function in \a send_ops.  */
-static void process_send_ops(grpc_call_element *elem,
-                             grpc_stream_op_buffer *send_ops) {
-  call_data *calld = elem->call_data;
-  channel_data *channeld = elem->channel_data;
-  size_t i;
-  int did_compress = 0;
+static void continue_send_message(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem);
 
-  /* In streaming calls, we need to reset the previously accumulated slices */
+static void send_done(grpc_exec_ctx *exec_ctx, void *elemp, int success) {
+  grpc_call_element *elem = elemp;
+  call_data *calld = elem->call_data;
   gpr_slice_buffer_reset_and_unref(&calld->slices);
-  for (i = 0; i < send_ops->nops; ++i) {
-    grpc_stream_op *sop = &send_ops->ops[i];
-    switch (sop->type) {
-      case GRPC_OP_BEGIN_MESSAGE:
-        /* buffer up slices until we've processed all the expected ones (as
-         * given by GRPC_OP_BEGIN_MESSAGE) */
-        calld->remaining_slice_bytes = sop->data.begin_message.length;
-        if (sop->data.begin_message.flags & GRPC_WRITE_NO_COMPRESS) {
-          calld->has_compression_algorithm = 1; /* GPR_TRUE */
-          calld->compression_algorithm = GRPC_COMPRESS_NONE;
-        }
-        break;
-      case GRPC_OP_METADATA:
-        if (!calld->written_initial_metadata) {
-          /* Parse incoming request for compression. If any, it'll be available
-           * at calld->compression_algorithm */
-          grpc_metadata_batch_filter(&(sop->data.metadata),
-                                     compression_md_filter, elem);
-          if (!calld->has_compression_algorithm) {
-            /* If no algorithm was found in the metadata and we aren't
-             * exceptionally skipping compression, fall back to the channel
-             * default */
-            calld->compression_algorithm =
-                channeld->default_compression_algorithm;
-            calld->has_compression_algorithm = 1; /* GPR_TRUE */
-          }
-          /* hint compression algorithm */
-          grpc_metadata_batch_add_tail(
-              &(sop->data.metadata), &calld->compression_algorithm_storage,
-              GRPC_MDELEM_REF(channeld->mdelem_compression_algorithms
-                                  [calld->compression_algorithm]));
-
-          /* convey supported compression algorithms */
-          grpc_metadata_batch_add_tail(
-              &(sop->data.metadata), &calld->accept_encoding_storage,
-              GRPC_MDELEM_REF(channeld->mdelem_accept_encoding));
-
-          calld->written_initial_metadata = 1; /* GPR_TRUE */
-        }
-        break;
-      case GRPC_OP_SLICE:
-        if (skip_compression(channeld, calld)) continue;
-        GPR_ASSERT(calld->remaining_slice_bytes > 0);
-        /* Increase input ref count, gpr_slice_buffer_add takes ownership.  */
-        gpr_slice_buffer_add(&calld->slices, gpr_slice_ref(sop->data.slice));
-        GPR_ASSERT(GPR_SLICE_LENGTH(sop->data.slice) <=
-                   calld->remaining_slice_bytes);
-        calld->remaining_slice_bytes -=
-            (gpr_uint32)GPR_SLICE_LENGTH(sop->data.slice);
-        if (calld->remaining_slice_bytes == 0) {
-          did_compress =
-              compress_send_sb(calld->compression_algorithm, &calld->slices);
-        }
-        break;
-      case GRPC_NO_OP:
-        break;
-    }
-  }
+  calld->post_send->cb(exec_ctx, calld->post_send->cb_arg, success);
+}
 
-  /* Modify the send_ops stream_op_buffer depending on whether compression was
-   * carried out */
+static void finish_send_message(grpc_exec_ctx *exec_ctx,
+                                grpc_call_element *elem) {
+  call_data *calld = elem->call_data;
+  int did_compress;
+  gpr_slice_buffer tmp;
+  gpr_slice_buffer_init(&tmp);
+  did_compress =
+      grpc_msg_compress(calld->compression_algorithm, &calld->slices, &tmp);
   if (did_compress) {
-    finish_compressed_sopb(send_ops, elem);
+    gpr_slice_buffer_swap(&calld->slices, &tmp);
+    calld->send_flags |= GRPC_WRITE_INTERNAL_COMPRESS;
+  }
+  gpr_slice_buffer_destroy(&tmp);
+
+  grpc_slice_buffer_stream_init(&calld->replacement_stream, &calld->slices,
+                                calld->send_flags);
+  calld->send_op.send_message = &calld->replacement_stream.base;
+  calld->post_send = calld->send_op.on_complete;
+  calld->send_op.on_complete = &calld->send_done;
+
+  grpc_call_next_op(exec_ctx, elem, &calld->send_op);
+}
+
+static void got_slice(grpc_exec_ctx *exec_ctx, void *elemp, int success) {
+  grpc_call_element *elem = elemp;
+  call_data *calld = elem->call_data;
+  gpr_slice_buffer_add(&calld->slices, calld->incoming_slice);
+  if (calld->send_length == calld->slices.length) {
+    finish_send_message(exec_ctx, elem);
+  } else {
+    continue_send_message(exec_ctx, elem);
+  }
+}
+
+static void continue_send_message(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem) {
+  call_data *calld = elem->call_data;
+  while (grpc_byte_stream_next(exec_ctx, calld->send_op.send_message,
+                               &calld->incoming_slice, ~(size_t)0,
+                               &calld->got_slice)) {
+    gpr_slice_buffer_add(&calld->slices, calld->incoming_slice);
+    if (calld->send_length == calld->slices.length) {
+      finish_send_message(exec_ctx, elem);
+      break;
+    }
   }
 }
 
-/* Called either:
-     - in response to an API call (or similar) from above, to send something
-     - a network event (or similar) from below, to receive something
-   op contains type and call direction information, in addition to the data
-   that is being sent or received. */
 static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
                                                grpc_call_element *elem,
                                                grpc_transport_stream_op *op) {
+  call_data *calld = elem->call_data;
+
   GPR_TIMER_BEGIN("compress_start_transport_stream_op", 0);
 
-  if (op->send_ops && op->send_ops->nops > 0) {
-    process_send_ops(elem, op->send_ops);
+  if (op->send_initial_metadata) {
+    process_send_initial_metadata(elem, op->send_initial_metadata);
+  }
+  if (op->send_message != NULL && !skip_compression(elem) &&
+      0 == (op->send_message->flags & GRPC_WRITE_NO_COMPRESS)) {
+    calld->send_op = *op;
+    calld->send_length = op->send_message->length;
+    calld->send_flags = op->send_message->flags;
+    continue_send_message(exec_ctx, elem);
+  } else {
+    /* pass control down the stack */
+    grpc_call_next_op(exec_ctx, elem, op);
   }
 
   GPR_TIMER_END("compress_start_transport_stream_op", 0);
-
-  /* pass control down the stack */
-  grpc_call_next_op(exec_ctx, elem, op);
 }
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+                           grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
 
   /* initialize members */
   gpr_slice_buffer_init(&calld->slices);
   calld->has_compression_algorithm = 0;
-  calld->written_initial_metadata = 0; /* GPR_FALSE */
-
-  if (initial_op) {
-    if (initial_op->send_ops && initial_op->send_ops->nops > 0) {
-      process_send_ops(elem, initial_op->send_ops);
-    }
-  }
+  grpc_closure_init(&calld->got_slice, got_slice, elem);
+  grpc_closure_init(&calld->send_done, send_done, elem);
 }
 
 /* Destructor for call_data */
@@ -313,85 +255,44 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
   channel_data *channeld = elem->channel_data;
   grpc_compression_algorithm algo_idx;
-  const char *supported_algorithms_names[GRPC_COMPRESS_ALGORITHMS_COUNT - 1];
-  size_t supported_algorithms_idx = 0;
-  char *accept_encoding_str;
-  size_t accept_encoding_str_len;
 
   grpc_compression_options_init(&channeld->compression_options);
   channeld->compression_options.enabled_algorithms_bitset =
-      (gpr_uint32)grpc_channel_args_compression_algorithm_get_states(args);
+      (gpr_uint32)grpc_channel_args_compression_algorithm_get_states(
+          args->channel_args);
 
   channeld->default_compression_algorithm =
-      grpc_channel_args_get_compression_algorithm(args);
+      grpc_channel_args_get_compression_algorithm(args->channel_args);
   /* Make sure the default isn't disabled. */
   GPR_ASSERT(grpc_compression_options_is_algorithm_enabled(
       &channeld->compression_options, channeld->default_compression_algorithm));
   channeld->compression_options.default_compression_algorithm =
       channeld->default_compression_algorithm;
 
-  channeld->mdstr_request_compression_algorithm_key =
-      grpc_mdstr_from_string(mdctx, GRPC_COMPRESS_REQUEST_ALGORITHM_KEY);
-
-  channeld->mdstr_outgoing_compression_algorithm_key =
-      grpc_mdstr_from_string(mdctx, "grpc-encoding");
-
-  channeld->mdstr_compression_capabilities_key =
-      grpc_mdstr_from_string(mdctx, "grpc-accept-encoding");
-
+  channeld->supported_compression_algorithms = 0;
   for (algo_idx = 0; algo_idx < GRPC_COMPRESS_ALGORITHMS_COUNT; ++algo_idx) {
-    char *algorithm_name;
     /* skip disabled algorithms */
     if (grpc_compression_options_is_algorithm_enabled(
             &channeld->compression_options, algo_idx) == 0) {
       continue;
     }
-    GPR_ASSERT(grpc_compression_algorithm_name(algo_idx, &algorithm_name) != 0);
-    channeld->mdelem_compression_algorithms[algo_idx] =
-        grpc_mdelem_from_metadata_strings(
-            mdctx,
-            GRPC_MDSTR_REF(channeld->mdstr_outgoing_compression_algorithm_key),
-            grpc_mdstr_from_string(mdctx, algorithm_name));
-    if (algo_idx > 0) {
-      supported_algorithms_names[supported_algorithms_idx++] = algorithm_name;
-    }
+    channeld->supported_compression_algorithms |= 1u << algo_idx;
   }
 
-  /* TODO(dgq): gpr_strjoin_sep could be made to work with statically allocated
-   * arrays, as to avoid the heap allocs */
-  accept_encoding_str =
-      gpr_strjoin_sep(supported_algorithms_names, supported_algorithms_idx, ",",
-                      &accept_encoding_str_len);
-
-  channeld->mdelem_accept_encoding = grpc_mdelem_from_metadata_strings(
-      mdctx, GRPC_MDSTR_REF(channeld->mdstr_compression_capabilities_key),
-      grpc_mdstr_from_string(mdctx, accept_encoding_str));
-  gpr_free(accept_encoding_str);
-
-  GPR_ASSERT(!is_last);
+  GPR_ASSERT(!args->is_last);
 }
 
 /* Destructor for channel data */
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {
-  channel_data *channeld = elem->channel_data;
-  grpc_compression_algorithm algo_idx;
-
-  GRPC_MDSTR_UNREF(channeld->mdstr_request_compression_algorithm_key);
-  GRPC_MDSTR_UNREF(channeld->mdstr_outgoing_compression_algorithm_key);
-  GRPC_MDSTR_UNREF(channeld->mdstr_compression_capabilities_key);
-  for (algo_idx = 0; algo_idx < GRPC_COMPRESS_ALGORITHMS_COUNT; ++algo_idx) {
-    GRPC_MDELEM_UNREF(channeld->mdelem_compression_algorithms[algo_idx]);
-  }
-  GRPC_MDELEM_UNREF(channeld->mdelem_accept_encoding);
 }
 
 const grpc_channel_filter grpc_compress_filter = {
     compress_start_transport_stream_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem, destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, grpc_call_next_get_peer, "compress"};
+    init_call_elem, grpc_call_stack_ignore_set_pollset, destroy_call_elem,
+    sizeof(channel_data), init_channel_elem, destroy_channel_elem,
+    grpc_call_next_get_peer, "compress"};

src/core/channel/connected_channel.c

@@ -83,8 +83,7 @@ static void con_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+                           grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   int r;
@@ -92,10 +91,18 @@ static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
   r = grpc_transport_init_stream(exec_ctx, chand->transport,
                                  TRANSPORT_STREAM_FROM_CALL_DATA(calld),
-                                 server_transport_data, initial_op);
+                                 args->refcount, args->server_transport_data);
   GPR_ASSERT(r == 0);
 }
 
+static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                        grpc_pollset *pollset) {
+  call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
+  grpc_transport_set_pollset(exec_ctx, chand->transport,
+                             TRANSPORT_STREAM_FROM_CALL_DATA(calld), pollset);
+}
+
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
                               grpc_call_element *elem) {
@@ -108,11 +115,10 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
   channel_data *cd = (channel_data *)elem->channel_data;
-  GPR_ASSERT(is_last);
+  GPR_ASSERT(args->is_last);
   GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
   cd->transport = NULL;
 }
@@ -132,8 +138,8 @@ static char *con_get_peer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
 
 const grpc_channel_filter grpc_connected_channel_filter = {
     con_start_transport_stream_op, con_start_transport_op, sizeof(call_data),
-    init_call_elem, destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, con_get_peer, "connected",
+    init_call_elem, set_pollset, destroy_call_elem, sizeof(channel_data),
+    init_channel_elem, destroy_channel_elem, con_get_peer, "connected",
 };
 
 void grpc_connected_channel_bind_transport(grpc_channel_stack *channel_stack,
@@ -154,3 +160,8 @@ void grpc_connected_channel_bind_transport(grpc_channel_stack *channel_stack,
      channel. */
   channel_stack->call_stack_size += grpc_transport_stream_size(transport);
 }
+
+grpc_stream *grpc_connected_channel_get_stream(grpc_call_element *elem) {
+  call_data *calld = elem->call_data;
+  return TRANSPORT_STREAM_FROM_CALL_DATA(calld);
+}

src/core/channel/connected_channel.h

@@ -46,4 +46,6 @@ extern const grpc_channel_filter grpc_connected_channel_filter;
 void grpc_connected_channel_bind_transport(grpc_channel_stack* channel_stack,
                                            grpc_transport* transport);
 
+grpc_stream* grpc_connected_channel_get_stream(grpc_call_element* elem);
+
 #endif /* GRPC_INTERNAL_CORE_CHANNEL_CONNECTED_CHANNEL_H */

src/core/channel/http_client_filter.c

@@ -37,6 +37,7 @@
 #include <grpc/support/string_util.h>
 #include "src/core/support/string.h"
 #include "src/core/profiling/timers.h"
+#include "src/core/transport/static_metadata.h"
 
 typedef struct call_data {
   grpc_linked_mdelem method;
@@ -45,10 +46,8 @@ typedef struct call_data {
   grpc_linked_mdelem te_trailers;
   grpc_linked_mdelem content_type;
   grpc_linked_mdelem user_agent;
-  int sent_initial_metadata;
 
-  int got_initial_metadata;
-  grpc_stream_op_buffer *recv_ops;
+  grpc_metadata_batch *recv_initial_metadata;
 
   /** Closure to call when finished with the hc_on_recv hook */
   grpc_closure *on_done_recv;
@@ -59,12 +58,7 @@ typedef struct call_data {
 } call_data;
 
 typedef struct channel_data {
-  grpc_mdelem *te_trailers;
-  grpc_mdelem *method;
-  grpc_mdelem *scheme;
-  grpc_mdelem *content_type;
-  grpc_mdelem *status;
-  /** complete user agent mdelem */
+  grpc_mdelem *static_scheme;
   grpc_mdelem *user_agent;
 } channel_data;
 
@@ -75,14 +69,12 @@ typedef struct {
 
 static grpc_mdelem *client_recv_filter(void *user_data, grpc_mdelem *md) {
   client_recv_filter_args *a = user_data;
-  grpc_call_element *elem = a->elem;
-  channel_data *channeld = elem->channel_data;
-  if (md == channeld->status) {
+  if (md == GRPC_MDELEM_STATUS_200) {
     return NULL;
-  } else if (md->key == channeld->status->key) {
-    grpc_call_element_send_cancel(a->exec_ctx, elem);
+  } else if (md->key == GRPC_MDSTR_STATUS) {
+    grpc_call_element_send_cancel(a->exec_ctx, a->elem);
     return NULL;
-  } else if (md->key == channeld->content_type->key) {
+  } else if (md->key == GRPC_MDSTR_CONTENT_TYPE) {
     return NULL;
   }
   return md;
@@ -91,30 +83,21 @@ static grpc_mdelem *client_recv_filter(void *user_data, grpc_mdelem *md) {
 static void hc_on_recv(grpc_exec_ctx *exec_ctx, void *user_data, int success) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
-  size_t i;
-  size_t nops = calld->recv_ops->nops;
-  grpc_stream_op *ops = calld->recv_ops->ops;
-  for (i = 0; i < nops; i++) {
-    grpc_stream_op *op = &ops[i];
-    client_recv_filter_args a;
-    if (op->type != GRPC_OP_METADATA) continue;
-    calld->got_initial_metadata = 1;
-    a.elem = elem;
-    a.exec_ctx = exec_ctx;
-    grpc_metadata_batch_filter(&op->data.metadata, client_recv_filter, &a);
-  }
+  client_recv_filter_args a;
+  a.elem = elem;
+  a.exec_ctx = exec_ctx;
+  grpc_metadata_batch_filter(calld->recv_initial_metadata, client_recv_filter,
+                             &a);
   calld->on_done_recv->cb(exec_ctx, calld->on_done_recv->cb_arg, success);
 }
 
 static grpc_mdelem *client_strip_filter(void *user_data, grpc_mdelem *md) {
-  grpc_call_element *elem = user_data;
-  channel_data *channeld = elem->channel_data;
   /* eat the things we'd like to set ourselves */
-  if (md->key == channeld->method->key) return NULL;
-  if (md->key == channeld->scheme->key) return NULL;
-  if (md->key == channeld->te_trailers->key) return NULL;
-  if (md->key == channeld->content_type->key) return NULL;
-  if (md->key == channeld->user_agent->key) return NULL;
+  if (md->key == GRPC_MDSTR_METHOD) return NULL;
+  if (md->key == GRPC_MDSTR_SCHEME) return NULL;
+  if (md->key == GRPC_MDSTR_TE) return NULL;
+  if (md->key == GRPC_MDSTR_CONTENT_TYPE) return NULL;
+  if (md->key == GRPC_MDSTR_USER_AGENT) return NULL;
   return md;
 }
 
@@ -123,40 +106,29 @@ static void hc_mutate_op(grpc_call_element *elem,
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
-  size_t i;
-  if (op->send_ops && !calld->sent_initial_metadata) {
-    size_t nops = op->send_ops->nops;
-    grpc_stream_op *ops = op->send_ops->ops;
-    for (i = 0; i < nops; i++) {
-      grpc_stream_op *stream_op = &ops[i];
-      if (stream_op->type != GRPC_OP_METADATA) continue;
-      calld->sent_initial_metadata = 1;
-      grpc_metadata_batch_filter(&stream_op->data.metadata, client_strip_filter,
-                                 elem);
-      /* Send : prefixed headers, which have to be before any application
-         layer headers. */
-      grpc_metadata_batch_add_head(&stream_op->data.metadata, &calld->method,
-                                   GRPC_MDELEM_REF(channeld->method));
-      grpc_metadata_batch_add_head(&stream_op->data.metadata, &calld->scheme,
-                                   GRPC_MDELEM_REF(channeld->scheme));
-      grpc_metadata_batch_add_tail(&stream_op->data.metadata,
-                                   &calld->te_trailers,
-                                   GRPC_MDELEM_REF(channeld->te_trailers));
-      grpc_metadata_batch_add_tail(&stream_op->data.metadata,
-                                   &calld->content_type,
-                                   GRPC_MDELEM_REF(channeld->content_type));
-      grpc_metadata_batch_add_tail(&stream_op->data.metadata,
-                                   &calld->user_agent,
-                                   GRPC_MDELEM_REF(channeld->user_agent));
-      break;
-    }
+  if (op->send_initial_metadata != NULL) {
+    grpc_metadata_batch_filter(op->send_initial_metadata, client_strip_filter,
+                               elem);
+    /* Send : prefixed headers, which have to be before any application
+       layer headers. */
+    grpc_metadata_batch_add_head(op->send_initial_metadata, &calld->method,
+                                 GRPC_MDELEM_METHOD_POST);
+    grpc_metadata_batch_add_head(op->send_initial_metadata, &calld->scheme,
+                                 channeld->static_scheme);
+    grpc_metadata_batch_add_tail(op->send_initial_metadata, &calld->te_trailers,
+                                 GRPC_MDELEM_TE_TRAILERS);
+    grpc_metadata_batch_add_tail(
+        op->send_initial_metadata, &calld->content_type,
+        GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC);
+    grpc_metadata_batch_add_tail(op->send_initial_metadata, &calld->user_agent,
+                                 GRPC_MDELEM_REF(channeld->user_agent));
   }
 
-  if (op->recv_ops && !calld->got_initial_metadata) {
+  if (op->recv_initial_metadata != NULL) {
     /* substitute our callback for the higher callback */
-    calld->recv_ops = op->recv_ops;
-    calld->on_done_recv = op->on_done_recv;
-    op->on_done_recv = &calld->hc_on_recv;
+    calld->recv_initial_metadata = op->recv_initial_metadata;
+    calld->on_done_recv = op->on_complete;
+    op->on_complete = &calld->hc_on_recv;
   }
 }
 
@@ -172,35 +144,38 @@ static void hc_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+                           grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
-  calld->sent_initial_metadata = 0;
-  calld->got_initial_metadata = 0;
   calld->on_done_recv = NULL;
   grpc_closure_init(&calld->hc_on_recv, hc_on_recv, elem);
-  if (initial_op) hc_mutate_op(elem, initial_op);
 }
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
                               grpc_call_element *elem) {}
 
-static const char *scheme_from_args(const grpc_channel_args *args) {
+static grpc_mdelem *scheme_from_args(const grpc_channel_args *args) {
   unsigned i;
+  size_t j;
+  grpc_mdelem *valid_schemes[] = {GRPC_MDELEM_SCHEME_HTTP,
+                                  GRPC_MDELEM_SCHEME_HTTPS};
   if (args != NULL) {
     for (i = 0; i < args->num_args; ++i) {
       if (args->args[i].type == GRPC_ARG_STRING &&
           strcmp(args->args[i].key, GRPC_ARG_HTTP2_SCHEME) == 0) {
-        return args->args[i].value.string;
+        for (j = 0; j < GPR_ARRAY_SIZE(valid_schemes); j++) {
+          if (0 == strcmp(grpc_mdstr_as_c_string(valid_schemes[j]->value),
+                          args->args[i].value.string)) {
+            return valid_schemes[j];
+          }
+        }
       }
     }
   }
-  return "http";
+  return GRPC_MDELEM_SCHEME_HTTP;
 }
 
-static grpc_mdstr *user_agent_from_args(grpc_mdctx *mdctx,
-                                        const grpc_channel_args *args) {
+static grpc_mdstr *user_agent_from_args(const grpc_channel_args *args) {
   gpr_strvec v;
   size_t i;
   int is_first = 1;
@@ -242,7 +217,7 @@ static grpc_mdstr *user_agent_from_args(grpc_mdctx *mdctx,
 
   tmp = gpr_strvec_flatten(&v, NULL);
   gpr_strvec_destroy(&v);
-  result = grpc_mdstr_from_string(mdctx, tmp);
+  result = grpc_mdstr_from_string(tmp);
   gpr_free(tmp);
 
   return result;
@@ -250,46 +225,24 @@ static grpc_mdstr *user_agent_from_args(grpc_mdctx *mdctx,
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *channel_args,
-                              grpc_mdctx *mdctx, int is_first, int is_last) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  /* The first and the last filters tend to be implemented differently to
-     handle the case that there's no 'next' filter to call on the up or down
-     path */
-  GPR_ASSERT(!is_last);
-
-  /* initialize members */
-  channeld->te_trailers = grpc_mdelem_from_strings(mdctx, "te", "trailers");
-  channeld->method = grpc_mdelem_from_strings(mdctx, ":method", "POST");
-  channeld->scheme = grpc_mdelem_from_strings(mdctx, ":scheme",
-                                              scheme_from_args(channel_args));
-  channeld->content_type =
-      grpc_mdelem_from_strings(mdctx, "content-type", "application/grpc");
-  channeld->status = grpc_mdelem_from_strings(mdctx, ":status", "200");
-  channeld->user_agent = grpc_mdelem_from_metadata_strings(
-      mdctx, grpc_mdstr_from_string(mdctx, "user-agent"),
-      user_agent_from_args(mdctx, channel_args));
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
+  channel_data *chand = elem->channel_data;
+  GPR_ASSERT(!args->is_last);
+  chand->static_scheme = scheme_from_args(args->channel_args);
+  chand->user_agent = grpc_mdelem_from_metadata_strings(
+      GRPC_MDSTR_USER_AGENT, user_agent_from_args(args->channel_args));
 }
 
 /* Destructor for channel data */
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  GRPC_MDELEM_UNREF(channeld->te_trailers);
-  GRPC_MDELEM_UNREF(channeld->method);
-  GRPC_MDELEM_UNREF(channeld->scheme);
-  GRPC_MDELEM_UNREF(channeld->content_type);
-  GRPC_MDELEM_UNREF(channeld->status);
-  GRPC_MDELEM_UNREF(channeld->user_agent);
+  channel_data *chand = elem->channel_data;
+  GRPC_MDELEM_UNREF(chand->user_agent);
 }
 
 const grpc_channel_filter grpc_http_client_filter = {
     hc_start_transport_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem,        destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,     destroy_channel_elem, grpc_call_next_get_peer,
-    "http-client"};
+    init_call_elem, grpc_call_stack_ignore_set_pollset, destroy_call_elem,
+    sizeof(channel_data), init_channel_elem, destroy_channel_elem,
+    grpc_call_next_get_peer, "http-client"};

src/core/channel/http_server_filter.c

@@ -37,9 +37,9 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include "src/core/profiling/timers.h"
+#include "src/core/transport/static_metadata.h"
 
 typedef struct call_data {
-  gpr_uint8 got_initial_metadata;
   gpr_uint8 seen_path;
   gpr_uint8 seen_post;
   gpr_uint8 sent_status;
@@ -49,7 +49,7 @@ typedef struct call_data {
   grpc_linked_mdelem status;
   grpc_linked_mdelem content_type;
 
-  grpc_stream_op_buffer *recv_ops;
+  grpc_metadata_batch *recv_initial_metadata;
   /** Closure to call when finished with the hs_on_recv hook */
   grpc_closure *on_done_recv;
   /** Receive closures are chained: we inject this closure as the on_done_recv
@@ -58,22 +58,7 @@ typedef struct call_data {
   grpc_closure hs_on_recv;
 } call_data;
 
-typedef struct channel_data {
-  grpc_mdelem *te_trailers;
-  grpc_mdelem *method_post;
-  grpc_mdelem *http_scheme;
-  grpc_mdelem *https_scheme;
-  /* TODO(klempner): Remove this once we stop using it */
-  grpc_mdelem *grpc_scheme;
-  grpc_mdelem *content_type;
-  grpc_mdelem *status_ok;
-  grpc_mdelem *status_not_found;
-  grpc_mdstr *path_key;
-  grpc_mdstr *authority_key;
-  grpc_mdstr *host_key;
-
-  grpc_mdctx *mdctx;
-} channel_data;
+typedef struct channel_data { gpr_uint8 unused; } channel_data;
 
 typedef struct {
   grpc_call_element *elem;
@@ -83,25 +68,24 @@ typedef struct {
 static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
   server_filter_args *a = user_data;
   grpc_call_element *elem = a->elem;
-  channel_data *channeld = elem->channel_data;
   call_data *calld = elem->call_data;
 
   /* Check if it is one of the headers we care about. */
-  if (md == channeld->te_trailers || md == channeld->method_post ||
-      md == channeld->http_scheme || md == channeld->https_scheme ||
-      md == channeld->grpc_scheme || md == channeld->content_type) {
+  if (md == GRPC_MDELEM_TE_TRAILERS || md == GRPC_MDELEM_METHOD_POST ||
+      md == GRPC_MDELEM_SCHEME_HTTP || md == GRPC_MDELEM_SCHEME_HTTPS ||
+      md == GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC) {
     /* swallow it */
-    if (md == channeld->method_post) {
+    if (md == GRPC_MDELEM_METHOD_POST) {
       calld->seen_post = 1;
-    } else if (md->key == channeld->http_scheme->key) {
+    } else if (md->key == GRPC_MDSTR_SCHEME) {
       calld->seen_scheme = 1;
-    } else if (md == channeld->te_trailers) {
+    } else if (md == GRPC_MDELEM_TE_TRAILERS) {
       calld->seen_te_trailers = 1;
     }
     /* TODO(klempner): Track that we've seen all the headers we should
        require */
     return NULL;
-  } else if (md->key == channeld->content_type->key) {
+  } else if (md->key == GRPC_MDSTR_CONTENT_TYPE) {
     if (strncmp(grpc_mdstr_as_c_string(md->value), "application/grpc+", 17) ==
         0) {
       /* Although the C implementation doesn't (currently) generate them,
@@ -113,12 +97,11 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
       /* TODO(klempner): We're currently allowing this, but we shouldn't
          see it without a proxy so log for now. */
       gpr_log(GPR_INFO, "Unexpected content-type %s",
-              channeld->content_type->key);
+              grpc_mdstr_as_c_string(md->value));
     }
     return NULL;
-  } else if (md->key == channeld->te_trailers->key ||
-             md->key == channeld->method_post->key ||
-             md->key == channeld->http_scheme->key) {
+  } else if (md->key == GRPC_MDSTR_TE || md->key == GRPC_MDSTR_METHOD ||
+             md->key == GRPC_MDSTR_SCHEME) {
     gpr_log(GPR_ERROR, "Invalid %s: header: '%s'",
             grpc_mdstr_as_c_string(md->key), grpc_mdstr_as_c_string(md->value));
     /* swallow it and error everything out. */
@@ -126,22 +109,21 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
        on the wire here. */
     grpc_call_element_send_cancel(a->exec_ctx, elem);
     return NULL;
-  } else if (md->key == channeld->path_key) {
+  } else if (md->key == GRPC_MDSTR_PATH) {
     if (calld->seen_path) {
       gpr_log(GPR_ERROR, "Received :path twice");
       return NULL;
     }
     calld->seen_path = 1;
     return md;
-  } else if (md->key == channeld->authority_key) {
+  } else if (md->key == GRPC_MDSTR_AUTHORITY) {
     calld->seen_authority = 1;
     return md;
-  } else if (md->key == channeld->host_key) {
+  } else if (md->key == GRPC_MDSTR_HOST) {
     /* translate host to :authority since :authority may be
        omitted */
     grpc_mdelem *authority = grpc_mdelem_from_metadata_strings(
-        channeld->mdctx, GRPC_MDSTR_REF(channeld->authority_key),
-        GRPC_MDSTR_REF(md->value));
+        GRPC_MDSTR_AUTHORITY, GRPC_MDSTR_REF(md->value));
     GRPC_MDELEM_UNREF(md);
     calld->seen_authority = 1;
     return authority;
@@ -154,43 +136,35 @@ static void hs_on_recv(grpc_exec_ctx *exec_ctx, void *user_data, int success) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
   if (success) {
-    size_t i;
-    size_t nops = calld->recv_ops->nops;
-    grpc_stream_op *ops = calld->recv_ops->ops;
-    for (i = 0; i < nops; i++) {
-      grpc_stream_op *op = &ops[i];
-      server_filter_args a;
-      if (op->type != GRPC_OP_METADATA) continue;
-      calld->got_initial_metadata = 1;
-      a.elem = elem;
-      a.exec_ctx = exec_ctx;
-      grpc_metadata_batch_filter(&op->data.metadata, server_filter, &a);
-      /* Have we seen the required http2 transport headers?
-         (:method, :scheme, content-type, with :path and :authority covered
-         at the channel level right now) */
-      if (calld->seen_post && calld->seen_scheme && calld->seen_te_trailers &&
-          calld->seen_path && calld->seen_authority) {
-        /* do nothing */
-      } else {
-        if (!calld->seen_path) {
-          gpr_log(GPR_ERROR, "Missing :path header");
-        }
-        if (!calld->seen_authority) {
-          gpr_log(GPR_ERROR, "Missing :authority header");
-        }
-        if (!calld->seen_post) {
-          gpr_log(GPR_ERROR, "Missing :method header");
-        }
-        if (!calld->seen_scheme) {
-          gpr_log(GPR_ERROR, "Missing :scheme header");
-        }
-        if (!calld->seen_te_trailers) {
-          gpr_log(GPR_ERROR, "Missing te trailers header");
-        }
-        /* Error this call out */
-        success = 0;
-        grpc_call_element_send_cancel(exec_ctx, elem);
+    server_filter_args a;
+    a.elem = elem;
+    a.exec_ctx = exec_ctx;
+    grpc_metadata_batch_filter(calld->recv_initial_metadata, server_filter, &a);
+    /* Have we seen the required http2 transport headers?
+       (:method, :scheme, content-type, with :path and :authority covered
+       at the channel level right now) */
+    if (calld->seen_post && calld->seen_scheme && calld->seen_te_trailers &&
+        calld->seen_path && calld->seen_authority) {
+      /* do nothing */
+    } else {
+      if (!calld->seen_path) {
+        gpr_log(GPR_ERROR, "Missing :path header");
+      }
+      if (!calld->seen_authority) {
+        gpr_log(GPR_ERROR, "Missing :authority header");
+      }
+      if (!calld->seen_post) {
+        gpr_log(GPR_ERROR, "Missing :method header");
+      }
+      if (!calld->seen_scheme) {
+        gpr_log(GPR_ERROR, "Missing :scheme header");
+      }
+      if (!calld->seen_te_trailers) {
+        gpr_log(GPR_ERROR, "Missing te trailers header");
       }
+      /* Error this call out */
+      success = 0;
+      grpc_call_element_send_cancel(exec_ctx, elem);
     }
   }
   calld->on_done_recv->cb(exec_ctx, calld->on_done_recv->cb_arg, success);
@@ -200,30 +174,21 @@ static void hs_mutate_op(grpc_call_element *elem,
                          grpc_transport_stream_op *op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
-  channel_data *channeld = elem->channel_data;
-  size_t i;
 
-  if (op->send_ops && !calld->sent_status) {
-    size_t nops = op->send_ops->nops;
-    grpc_stream_op *ops = op->send_ops->ops;
-    for (i = 0; i < nops; i++) {
-      grpc_stream_op *stream_op = &ops[i];
-      if (stream_op->type != GRPC_OP_METADATA) continue;
-      calld->sent_status = 1;
-      grpc_metadata_batch_add_head(&stream_op->data.metadata, &calld->status,
-                                   GRPC_MDELEM_REF(channeld->status_ok));
-      grpc_metadata_batch_add_tail(&stream_op->data.metadata,
-                                   &calld->content_type,
-                                   GRPC_MDELEM_REF(channeld->content_type));
-      break;
-    }
+  if (op->send_initial_metadata != NULL && !calld->sent_status) {
+    calld->sent_status = 1;
+    grpc_metadata_batch_add_head(op->send_initial_metadata, &calld->status,
+                                 GRPC_MDELEM_STATUS_200);
+    grpc_metadata_batch_add_tail(
+        op->send_initial_metadata, &calld->content_type,
+        GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC);
   }
 
-  if (op->recv_ops && !calld->got_initial_metadata) {
+  if (op->recv_initial_metadata) {
     /* substitute our callback for the higher callback */
-    calld->recv_ops = op->recv_ops;
-    calld->on_done_recv = op->on_done_recv;
-    op->on_done_recv = &calld->hs_on_recv;
+    calld->recv_initial_metadata = op->recv_initial_metadata;
+    calld->on_done_recv = op->on_complete;
+    op->on_complete = &calld->hs_on_recv;
   }
 }
 
@@ -239,14 +204,12 @@ static void hs_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+                           grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   /* initialize members */
   memset(calld, 0, sizeof(*calld));
   grpc_closure_init(&calld->hs_on_recv, hs_on_recv, elem);
-  if (initial_op) hs_mutate_op(elem, initial_op);
 }
 
 /* Destructor for call_data */
@@ -255,57 +218,18 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  /* The first and the last filters tend to be implemented differently to
-     handle the case that there's no 'next' filter to call on the up or down
-     path */
-  GPR_ASSERT(!is_first);
-  GPR_ASSERT(!is_last);
-
-  /* initialize members */
-  channeld->te_trailers = grpc_mdelem_from_strings(mdctx, "te", "trailers");
-  channeld->status_ok = grpc_mdelem_from_strings(mdctx, ":status", "200");
-  channeld->status_not_found =
-      grpc_mdelem_from_strings(mdctx, ":status", "404");
-  channeld->method_post = grpc_mdelem_from_strings(mdctx, ":method", "POST");
-  channeld->http_scheme = grpc_mdelem_from_strings(mdctx, ":scheme", "http");
-  channeld->https_scheme = grpc_mdelem_from_strings(mdctx, ":scheme", "https");
-  channeld->grpc_scheme = grpc_mdelem_from_strings(mdctx, ":scheme", "grpc");
-  channeld->path_key = grpc_mdstr_from_string(mdctx, ":path");
-  channeld->authority_key = grpc_mdstr_from_string(mdctx, ":authority");
-  channeld->host_key = grpc_mdstr_from_string(mdctx, "host");
-  channeld->content_type =
-      grpc_mdelem_from_strings(mdctx, "content-type", "application/grpc");
-
-  channeld->mdctx = mdctx;
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
+  GPR_ASSERT(!args->is_last);
 }
 
 /* Destructor for channel data */
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  GRPC_MDELEM_UNREF(channeld->te_trailers);
-  GRPC_MDELEM_UNREF(channeld->status_ok);
-  GRPC_MDELEM_UNREF(channeld->status_not_found);
-  GRPC_MDELEM_UNREF(channeld->method_post);
-  GRPC_MDELEM_UNREF(channeld->http_scheme);
-  GRPC_MDELEM_UNREF(channeld->https_scheme);
-  GRPC_MDELEM_UNREF(channeld->grpc_scheme);
-  GRPC_MDELEM_UNREF(channeld->content_type);
-  GRPC_MDSTR_UNREF(channeld->path_key);
-  GRPC_MDSTR_UNREF(channeld->authority_key);
-  GRPC_MDSTR_UNREF(channeld->host_key);
 }
 
 const grpc_channel_filter grpc_http_server_filter = {
     hs_start_transport_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem,        destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,     destroy_channel_elem, grpc_call_next_get_peer,
-    "http-server"};
+    init_call_elem, grpc_call_stack_ignore_set_pollset, destroy_call_elem,
+    sizeof(channel_data), init_channel_elem, destroy_channel_elem,
+    grpc_call_next_get_peer, "http-server"};

src/core/channel/noop_filter.c

@@ -73,16 +73,13 @@ static void noop_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+                           grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
 
   /* initialize members */
   calld->unused = channeld->unused;
-
-  if (initial_op) noop_mutate_op(elem, initial_op);
 }
 
 /* Destructor for call_data */
@@ -91,17 +88,15 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
   /* grab pointers to our data from the channel element */
   channel_data *channeld = elem->channel_data;
 
-  /* The first and the last filters tend to be implemented differently to
-     handle the case that there's no 'next' filter to call on the up or down
+  /* The last filter tends to be implemented differently to
+     handle the case that there's no 'next' filter to call on the down
      path */
-  GPR_ASSERT(!is_first);
-  GPR_ASSERT(!is_last);
+  GPR_ASSERT(!args->is_last);
 
   /* initialize members */
   channeld->unused = 0;
@@ -118,5 +113,6 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
 
 const grpc_channel_filter grpc_no_op_filter = {
     noop_start_transport_stream_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem, destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, grpc_call_next_get_peer, "no-op"};
+    init_call_elem, grpc_call_stack_ignore_set_pollset, destroy_call_elem,
+    sizeof(channel_data), init_channel_elem, destroy_channel_elem,
+    grpc_call_next_get_peer, "no-op"};

src/core/channel/subchannel_call_holder.c

@@ -0,0 +1,283 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/channel/subchannel_call_holder.h"
+
+#include <grpc/support/alloc.h>
+
+#include "src/core/profiling/timers.h"
+
+#define GET_CALL(holder) \
+  ((grpc_subchannel_call *)(gpr_atm_acq_load(&(holder)->subchannel_call)))
+
+#define CANCELLED_CALL ((grpc_subchannel_call *)1)
+
+static void subchannel_ready(grpc_exec_ctx *exec_ctx, void *holder,
+                             int success);
+static void call_ready(grpc_exec_ctx *exec_ctx, void *holder, int success);
+static void retry_ops(grpc_exec_ctx *exec_ctx, void *retry_ops_args,
+                      int success);
+
+static void add_waiting_locked(grpc_subchannel_call_holder *holder,
+                               grpc_transport_stream_op *op);
+static void fail_locked(grpc_exec_ctx *exec_ctx,
+                        grpc_subchannel_call_holder *holder);
+static void retry_waiting_locked(grpc_exec_ctx *exec_ctx,
+                                 grpc_subchannel_call_holder *holder);
+
+void grpc_subchannel_call_holder_init(
+    grpc_subchannel_call_holder *holder,
+    grpc_subchannel_call_holder_pick_subchannel pick_subchannel,
+    void *pick_subchannel_arg) {
+  gpr_atm_rel_store(&holder->subchannel_call, 0);
+  holder->pick_subchannel = pick_subchannel;
+  holder->pick_subchannel_arg = pick_subchannel_arg;
+  gpr_mu_init(&holder->mu);
+  holder->subchannel = NULL;
+  holder->waiting_ops = NULL;
+  holder->waiting_ops_count = 0;
+  holder->waiting_ops_capacity = 0;
+  holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
+}
+
+void grpc_subchannel_call_holder_destroy(grpc_exec_ctx *exec_ctx,
+                                         grpc_subchannel_call_holder *holder) {
+  grpc_subchannel_call *call = GET_CALL(holder);
+  if (call != NULL && call != CANCELLED_CALL) {
+    GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, call, "holder");
+  }
+  GPR_ASSERT(holder->creation_phase ==
+             GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING);
+  gpr_mu_destroy(&holder->mu);
+  GPR_ASSERT(holder->waiting_ops_count == 0);
+  gpr_free(holder->waiting_ops);
+}
+
+void grpc_subchannel_call_holder_perform_op(grpc_exec_ctx *exec_ctx,
+                                            grpc_subchannel_call_holder *holder,
+                                            grpc_transport_stream_op *op) {
+  /* try to (atomically) get the call */
+  grpc_subchannel_call *call = GET_CALL(holder);
+  GPR_TIMER_BEGIN("grpc_subchannel_call_holder_perform_op", 0);
+  if (call == CANCELLED_CALL) {
+    grpc_transport_stream_op_finish_with_failure(exec_ctx, op);
+    GPR_TIMER_END("grpc_subchannel_call_holder_perform_op", 0);
+    return;
+  }
+  if (call != NULL) {
+    grpc_subchannel_call_process_op(exec_ctx, call, op);
+    GPR_TIMER_END("grpc_subchannel_call_holder_perform_op", 0);
+    return;
+  }
+  /* we failed; lock and figure out what to do */
+  gpr_mu_lock(&holder->mu);
+retry:
+  /* need to recheck that another thread hasn't set the call */
+  call = GET_CALL(holder);
+  if (call == CANCELLED_CALL) {
+    gpr_mu_unlock(&holder->mu);
+    grpc_transport_stream_op_finish_with_failure(exec_ctx, op);
+    GPR_TIMER_END("grpc_subchannel_call_holder_perform_op", 0);
+    return;
+  }
+  if (call != NULL) {
+    gpr_mu_unlock(&holder->mu);
+    grpc_subchannel_call_process_op(exec_ctx, call, op);
+    GPR_TIMER_END("grpc_subchannel_call_holder_perform_op", 0);
+    return;
+  }
+  /* if this is a cancellation, then we can raise our cancelled flag */
+  if (op->cancel_with_status != GRPC_STATUS_OK) {
+    if (!gpr_atm_rel_cas(&holder->subchannel_call, 0, 1)) {
+      goto retry;
+    } else {
+      switch (holder->creation_phase) {
+        case GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING:
+          fail_locked(exec_ctx, holder);
+          break;
+        case GRPC_SUBCHANNEL_CALL_HOLDER_CREATING_CALL:
+          grpc_subchannel_cancel_create_call(exec_ctx, holder->subchannel,
+                                             &holder->subchannel_call);
+          break;
+        case GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL:
+          holder->pick_subchannel(exec_ctx, holder->pick_subchannel_arg, NULL,
+                                  &holder->subchannel, NULL);
+          break;
+      }
+      gpr_mu_unlock(&holder->mu);
+      grpc_transport_stream_op_finish_with_failure(exec_ctx, op);
+      GPR_TIMER_END("grpc_subchannel_call_holder_perform_op", 0);
+      return;
+    }
+  }
+  /* if we don't have a subchannel, try to get one */
+  if (holder->creation_phase == GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING &&
+      holder->subchannel == NULL && op->send_initial_metadata != NULL) {
+    holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL;
+    grpc_closure_init(&holder->next_step, subchannel_ready, holder);
+    if (holder->pick_subchannel(exec_ctx, holder->pick_subchannel_arg,
+                                op->send_initial_metadata, &holder->subchannel,
+                                &holder->next_step)) {
+      holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
+    }
+  }
+  /* if we've got a subchannel, then let's ask it to create a call */
+  if (holder->creation_phase == GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING &&
+      holder->subchannel != NULL) {
+    holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_CREATING_CALL;
+    grpc_closure_init(&holder->next_step, call_ready, holder);
+    if (grpc_subchannel_create_call(exec_ctx, holder->subchannel,
+                                    holder->pollset, &holder->subchannel_call,
+                                    &holder->next_step)) {
+      /* got one immediately - continue the op (and any waiting ops) */
+      holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
+      retry_waiting_locked(exec_ctx, holder);
+      goto retry;
+    }
+  }
+  /* nothing to be done but wait */
+  add_waiting_locked(holder, op);
+  gpr_mu_unlock(&holder->mu);
+  GPR_TIMER_END("grpc_subchannel_call_holder_perform_op", 0);
+}
+
+static void subchannel_ready(grpc_exec_ctx *exec_ctx, void *arg, int success) {
+  grpc_subchannel_call_holder *holder = arg;
+  grpc_subchannel_call *call;
+  gpr_mu_lock(&holder->mu);
+  GPR_ASSERT(holder->creation_phase ==
+             GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL);
+  call = GET_CALL(holder);
+  GPR_ASSERT(call == NULL || call == CANCELLED_CALL);
+  if (holder->subchannel == NULL) {
+    holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
+    fail_locked(exec_ctx, holder);
+  } else {
+    grpc_closure_init(&holder->next_step, call_ready, holder);
+    if (grpc_subchannel_create_call(exec_ctx, holder->subchannel,
+                                    holder->pollset, &holder->subchannel_call,
+                                    &holder->next_step)) {
+      holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
+      /* got one immediately - continue the op (and any waiting ops) */
+      retry_waiting_locked(exec_ctx, holder);
+    }
+  }
+  gpr_mu_unlock(&holder->mu);
+}
+
+static void call_ready(grpc_exec_ctx *exec_ctx, void *arg, int success) {
+  grpc_subchannel_call_holder *holder = arg;
+  GPR_TIMER_BEGIN("call_ready", 0);
+  gpr_mu_lock(&holder->mu);
+  GPR_ASSERT(holder->creation_phase ==
+             GRPC_SUBCHANNEL_CALL_HOLDER_CREATING_CALL);
+  holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
+  if (GET_CALL(holder) != NULL) {
+    retry_waiting_locked(exec_ctx, holder);
+  } else {
+    fail_locked(exec_ctx, holder);
+  }
+  gpr_mu_unlock(&holder->mu);
+  GPR_TIMER_END("call_ready", 0);
+}
+
+typedef struct {
+  grpc_transport_stream_op *ops;
+  size_t nops;
+  grpc_subchannel_call *call;
+} retry_ops_args;
+
+static void retry_waiting_locked(grpc_exec_ctx *exec_ctx,
+                                 grpc_subchannel_call_holder *holder) {
+  retry_ops_args *a = gpr_malloc(sizeof(*a));
+  a->ops = holder->waiting_ops;
+  a->nops = holder->waiting_ops_count;
+  a->call = GET_CALL(holder);
+  if (a->call == CANCELLED_CALL) {
+    gpr_free(a);
+    fail_locked(exec_ctx, holder);
+    return;
+  }
+  holder->waiting_ops = NULL;
+  holder->waiting_ops_count = 0;
+  holder->waiting_ops_capacity = 0;
+  GRPC_SUBCHANNEL_CALL_REF(a->call, "retry_ops");
+  grpc_exec_ctx_enqueue(exec_ctx, grpc_closure_create(retry_ops, a), 1);
+}
+
+static void retry_ops(grpc_exec_ctx *exec_ctx, void *args, int success) {
+  retry_ops_args *a = args;
+  size_t i;
+  for (i = 0; i < a->nops; i++) {
+    grpc_subchannel_call_process_op(exec_ctx, a->call, &a->ops[i]);
+  }
+  GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, a->call, "retry_ops");
+  gpr_free(a->ops);
+  gpr_free(a);
+}
+
+static void add_waiting_locked(grpc_subchannel_call_holder *holder,
+                               grpc_transport_stream_op *op) {
+  GPR_TIMER_BEGIN("add_waiting_locked", 0);
+  if (holder->waiting_ops_count == holder->waiting_ops_capacity) {
+    holder->waiting_ops_capacity = GPR_MAX(3, 2 * holder->waiting_ops_capacity);
+    holder->waiting_ops =
+        gpr_realloc(holder->waiting_ops, holder->waiting_ops_capacity *
+                                             sizeof(*holder->waiting_ops));
+  }
+  holder->waiting_ops[holder->waiting_ops_count++] = *op;
+  GPR_TIMER_END("add_waiting_locked", 0);
+}
+
+static void fail_locked(grpc_exec_ctx *exec_ctx,
+                        grpc_subchannel_call_holder *holder) {
+  size_t i;
+  for (i = 0; i < holder->waiting_ops_count; i++) {
+    grpc_exec_ctx_enqueue(exec_ctx, holder->waiting_ops[i].on_complete, 0);
+    grpc_exec_ctx_enqueue(exec_ctx, holder->waiting_ops[i].recv_message_ready,
+                          0);
+  }
+  holder->waiting_ops_count = 0;
+}
+
+char *grpc_subchannel_call_holder_get_peer(grpc_exec_ctx *exec_ctx,
+                                           grpc_subchannel_call_holder *holder,
+                                           grpc_channel *master) {
+  grpc_subchannel_call *subchannel_call = GET_CALL(holder);
+
+  if (subchannel_call) {
+    return grpc_subchannel_call_get_peer(exec_ctx, subchannel_call);
+  } else {
+    return grpc_channel_get_target(master);
+  }
+}

src/core/channel/subchannel_call_holder.h

@@ -0,0 +1,98 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CHANNEL_SUBCHANNEL_CALL_HOLDER_H
+#define GRPC_INTERNAL_CORE_CHANNEL_SUBCHANNEL_CALL_HOLDER_H
+
+#include "src/core/client_config/subchannel.h"
+
+/** Pick a subchannel for grpc_subchannel_call_holder;
+    Return 1 if subchannel is available immediately (in which case on_ready
+    should not be called), or 0 otherwise (in which case on_ready should be
+    called when the subchannel is available) */
+typedef int (*grpc_subchannel_call_holder_pick_subchannel)(
+    grpc_exec_ctx *exec_ctx, void *arg, grpc_metadata_batch *initial_metadata,
+    grpc_subchannel **subchannel, grpc_closure *on_ready);
+
+typedef enum {
+  GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING,
+  GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL,
+  GRPC_SUBCHANNEL_CALL_HOLDER_CREATING_CALL
+} grpc_subchannel_call_holder_creation_phase;
+
+/** Wrapper for holding a pointer to grpc_subchannel_call, and the
+    associated machinery to create such a pointer.
+    Handles queueing of stream ops until a call object is ready, waiting
+    for initial metadata before trying to create a call object,
+    and handling cancellation gracefully.
+
+    Both the channel and uchannel filter use this as their call_data. */
+typedef struct grpc_subchannel_call_holder {
+  /** either 0 for no call, 1 for cancelled, or a pointer to a
+      grpc_subchannel_call */
+  gpr_atm subchannel_call;
+  /** Helper function to choose the subchannel on which to create
+      the call object. Channel filter delegates to the load
+      balancing policy (once it's ready); uchannel returns
+      immediately */
+  grpc_subchannel_call_holder_pick_subchannel pick_subchannel;
+  void *pick_subchannel_arg;
+
+  gpr_mu mu;
+
+  grpc_subchannel_call_holder_creation_phase creation_phase;
+  grpc_subchannel *subchannel;
+  grpc_pollset *pollset;
+
+  grpc_transport_stream_op *waiting_ops;
+  size_t waiting_ops_count;
+  size_t waiting_ops_capacity;
+
+  grpc_closure next_step;
+} grpc_subchannel_call_holder;
+
+void grpc_subchannel_call_holder_init(
+    grpc_subchannel_call_holder *holder,
+    grpc_subchannel_call_holder_pick_subchannel pick_subchannel,
+    void *pick_subchannel_arg);
+void grpc_subchannel_call_holder_destroy(grpc_exec_ctx *exec_ctx,
+                                         grpc_subchannel_call_holder *holder);
+
+void grpc_subchannel_call_holder_perform_op(grpc_exec_ctx *exec_ctx,
+                                            grpc_subchannel_call_holder *holder,
+                                            grpc_transport_stream_op *op);
+char *grpc_subchannel_call_holder_get_peer(grpc_exec_ctx *exec_ctx,
+                                           grpc_subchannel_call_holder *holder,
+                                           grpc_channel *master);
+
+#endif

src/core/client_config/connector.h

@@ -51,6 +51,8 @@ typedef struct {
   /** address to connect to */
   const struct sockaddr *addr;
   size_t addr_len;
+  /** initial connect string to send */
+  gpr_slice initial_connect_string;
   /** deadline for connection */
   gpr_timespec deadline;
   /** channel arguments (to be passed to transport) */

src/core/client_config/default_initial_connect_string.c

@@ -0,0 +1,39 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <grpc/support/slice.h>
+#include "src/core/iomgr/sockaddr.h"
+
+void grpc_set_default_initial_connect_string(struct sockaddr **addr,
+                                             size_t *addr_len,
+                                             gpr_slice *initial_str) {}

src/core/client_config/initial_connect_string.c

@@ -0,0 +1,53 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/client_config/initial_connect_string.h"
+
+#include <stddef.h>
+
+extern void grpc_set_default_initial_connect_string(struct sockaddr **addr,
+                                                    size_t *addr_len,
+                                                    gpr_slice *initial_str);
+
+static grpc_set_initial_connect_string_func g_set_initial_connect_string_func =
+    grpc_set_default_initial_connect_string;
+
+void grpc_test_set_initial_connect_string_function(
+    grpc_set_initial_connect_string_func func) {
+  g_set_initial_connect_string_func = func;
+}
+
+void grpc_set_initial_connect_string(struct sockaddr **addr, size_t *addr_len,
+                                     gpr_slice *initial_str) {
+  g_set_initial_connect_string_func(addr, addr_len, initial_str);
+}

src/core/client_config/initial_connect_string.h

@@ -0,0 +1,50 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_INITIAL_CONNECT_STRING_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_INITIAL_CONNECT_STRING_H
+
+#include <grpc/support/slice.h>
+#include "src/core/iomgr/sockaddr.h"
+
+typedef void (*grpc_set_initial_connect_string_func)(struct sockaddr **addr,
+                                                     size_t *addr_len,
+                                                     gpr_slice *initial_str);
+void grpc_test_set_initial_connect_string_function(
+    grpc_set_initial_connect_string_func func);
+
+/** Set a string to be sent once connected. Optionally reset addr. */
+void grpc_set_initial_connect_string(struct sockaddr **addr, size_t *addr_len,
+                                     gpr_slice *connect_string);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_INITIAL_CONNECT_STRING_H */

src/core/client_config/lb_policies/pick_first.c

@@ -130,6 +130,30 @@ void pf_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   }
 }
 
+static void pf_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                           grpc_subchannel **target) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  pending_pick *pp;
+  gpr_mu_lock(&p->mu);
+  pp = p->pending_picks;
+  p->pending_picks = NULL;
+  while (pp != NULL) {
+    pending_pick *next = pp->next;
+    if (pp->target == target) {
+      grpc_subchannel_del_interested_party(
+          exec_ctx, p->subchannels[p->checking_subchannel], pp->pollset);
+      *target = NULL;
+      grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, 0);
+      gpr_free(pp);
+    } else {
+      pp->next = p->pending_picks;
+      p->pending_picks = pp;
+    }
+    pp = next;
+  }
+  gpr_mu_unlock(&p->mu);
+}
+
 static void start_picking(grpc_exec_ctx *exec_ctx, pick_first_lb_policy *p) {
   p->started_picking = 1;
   p->checking_subchannel = 0;
@@ -149,16 +173,16 @@ void pf_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   gpr_mu_unlock(&p->mu);
 }
 
-void pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-             grpc_pollset *pollset, grpc_metadata_batch *initial_metadata,
-             grpc_subchannel **target, grpc_closure *on_complete) {
+int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_pollset *pollset,
+            grpc_metadata_batch *initial_metadata, grpc_subchannel **target,
+            grpc_closure *on_complete) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   pending_pick *pp;
   gpr_mu_lock(&p->mu);
   if (p->selected) {
     gpr_mu_unlock(&p->mu);
     *target = p->selected;
-    grpc_exec_ctx_enqueue(exec_ctx, on_complete, 1);
+    return 1;
   } else {
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
@@ -172,6 +196,7 @@ void pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pp->on_complete = on_complete;
     p->pending_picks = pp;
     gpr_mu_unlock(&p->mu);
+    return 0;
   }
 }
 
@@ -365,8 +390,8 @@ void pf_notify_on_state_change(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
 }
 
 static const grpc_lb_policy_vtable pick_first_lb_policy_vtable = {
-    pf_destroy, pf_shutdown, pf_pick, pf_exit_idle, pf_broadcast,
-    pf_check_connectivity, pf_notify_on_state_change};
+    pf_destroy, pf_shutdown, pf_pick, pf_cancel_pick, pf_exit_idle,
+    pf_broadcast, pf_check_connectivity, pf_notify_on_state_change};
 
 static void pick_first_factory_ref(grpc_lb_policy_factory *factory) {}
 

src/core/client_config/lb_policies/round_robin.c

@@ -264,6 +264,33 @@ void rr_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   gpr_mu_unlock(&p->mu);
 }
 
+static void rr_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                           grpc_subchannel **target) {
+  round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
+  pending_pick *pp;
+  size_t i;
+  gpr_mu_lock(&p->mu);
+  pp = p->pending_picks;
+  p->pending_picks = NULL;
+  while (pp != NULL) {
+    pending_pick *next = pp->next;
+    if (pp->target == target) {
+      for (i = 0; i < p->num_subchannels; i++) {
+        grpc_subchannel_add_interested_party(exec_ctx, p->subchannels[i],
+                                             pp->pollset);
+      }
+      *target = NULL;
+      grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, 0);
+      gpr_free(pp);
+    } else {
+      pp->next = p->pending_picks;
+      p->pending_picks = pp;
+    }
+    pp = next;
+  }
+  gpr_mu_unlock(&p->mu);
+}
+
 static void start_picking(grpc_exec_ctx *exec_ctx, round_robin_lb_policy *p) {
   size_t i;
   p->started_picking = 1;
@@ -286,9 +313,9 @@ void rr_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   gpr_mu_unlock(&p->mu);
 }
 
-void rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-             grpc_pollset *pollset, grpc_metadata_batch *initial_metadata,
-             grpc_subchannel **target, grpc_closure *on_complete) {
+int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_pollset *pollset,
+            grpc_metadata_batch *initial_metadata, grpc_subchannel **target,
+            grpc_closure *on_complete) {
   size_t i;
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
   pending_pick *pp;
@@ -303,7 +330,7 @@ void rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     }
     /* only advance the last picked pointer if the selection was used */
     advance_last_picked_locked(p);
-    on_complete->cb(exec_ctx, on_complete->cb_arg, 1);
+    return 1;
   } else {
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
@@ -319,6 +346,7 @@ void rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pp->on_complete = on_complete;
     p->pending_picks = pp;
     gpr_mu_unlock(&p->mu);
+    return 0;
   }
 }
 
@@ -487,8 +515,8 @@ static void rr_notify_on_state_change(grpc_exec_ctx *exec_ctx,
 }
 
 static const grpc_lb_policy_vtable round_robin_lb_policy_vtable = {
-    rr_destroy, rr_shutdown, rr_pick, rr_exit_idle, rr_broadcast,
-    rr_check_connectivity, rr_notify_on_state_change};
+    rr_destroy, rr_shutdown, rr_pick, rr_cancel_pick, rr_exit_idle,
+    rr_broadcast, rr_check_connectivity, rr_notify_on_state_change};
 
 static void round_robin_factory_ref(grpc_lb_policy_factory *factory) {}
 

src/core/client_config/lb_policy.c

@@ -68,12 +68,17 @@ void grpc_lb_policy_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy) {
   policy->vtable->shutdown(exec_ctx, policy);
 }
 
-void grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                         grpc_pollset *pollset,
-                         grpc_metadata_batch *initial_metadata,
-                         grpc_subchannel **target, grpc_closure *on_complete) {
-  policy->vtable->pick(exec_ctx, policy, pollset, initial_metadata, target,
-                       on_complete);
+int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                        grpc_pollset *pollset,
+                        grpc_metadata_batch *initial_metadata,
+                        grpc_subchannel **target, grpc_closure *on_complete) {
+  return policy->vtable->pick(exec_ctx, policy, pollset, initial_metadata,
+                              target, on_complete);
+}
+
+void grpc_lb_policy_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                                grpc_subchannel **target) {
+  policy->vtable->cancel_pick(exec_ctx, policy, target);
 }
 
 void grpc_lb_policy_broadcast(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,

src/core/client_config/lb_policy.h

@@ -56,9 +56,11 @@ struct grpc_lb_policy_vtable {
   void (*shutdown)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
 
   /** implement grpc_lb_policy_pick */
-  void (*pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-               grpc_pollset *pollset, grpc_metadata_batch *initial_metadata,
-               grpc_subchannel **target, grpc_closure *on_complete);
+  int (*pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+              grpc_pollset *pollset, grpc_metadata_batch *initial_metadata,
+              grpc_subchannel **target, grpc_closure *on_complete);
+  void (*cancel_pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                      grpc_subchannel **target);
 
   /** try to enter a READY connectivity state */
   void (*exit_idle)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
@@ -106,10 +108,13 @@ void grpc_lb_policy_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
     target for this rpc, and 'return' it by calling \a on_complete after setting
     \a target.
     Picking can be asynchronous. Any IO should be done under \a pollset. */
-void grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                         grpc_pollset *pollset,
-                         grpc_metadata_batch *initial_metadata,
-                         grpc_subchannel **target, grpc_closure *on_complete);
+int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                        grpc_pollset *pollset,
+                        grpc_metadata_batch *initial_metadata,
+                        grpc_subchannel **target, grpc_closure *on_complete);
+
+void grpc_lb_policy_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                                grpc_subchannel **target);
 
 void grpc_lb_policy_broadcast(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                               grpc_transport_op *op);

src/core/client_config/subchannel.c

@@ -40,9 +40,12 @@
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
 #include "src/core/channel/connected_channel.h"
+#include "src/core/client_config/initial_connect_string.h"
 #include "src/core/iomgr/timer.h"
-#include "src/core/transport/connectivity_state.h"
+#include "src/core/profiling/timers.h"
 #include "src/core/surface/channel.h"
+#include "src/core/transport/connectivity_state.h"
+#include "src/core/transport/connectivity_state.h"
 
 #define GRPC_SUBCHANNEL_MIN_CONNECT_TIMEOUT_SECONDS 20
 #define GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS 1
@@ -69,7 +72,7 @@ typedef struct waiting_for_connect {
   struct waiting_for_connect *next;
   grpc_closure *notify;
   grpc_pollset *pollset;
-  grpc_subchannel_call **target;
+  gpr_atm *target;
   grpc_subchannel *subchannel;
   grpc_closure continuation;
 } waiting_for_connect;
@@ -85,8 +88,8 @@ struct grpc_subchannel {
   /** address to connect to */
   struct sockaddr *addr;
   size_t addr_len;
-  /** metadata context */
-  grpc_mdctx *mdctx;
+  /** initial string to send to peer */
+  gpr_slice initial_connect_string;
   /** master channel - the grpc_channel instance that ultimately owns
       this channel_data via its channel stack.
       We occasionally use this to bump the refcount on the master channel
@@ -137,14 +140,16 @@ struct grpc_subchannel {
 
 struct grpc_subchannel_call {
   connection *connection;
-  gpr_refcount refs;
 };
 
 #define SUBCHANNEL_CALL_TO_CALL_STACK(call) ((grpc_call_stack *)((call) + 1))
 #define CHANNEL_STACK_FROM_CONNECTION(con) ((grpc_channel_stack *)((con) + 1))
+#define CALLSTACK_TO_SUBCHANNEL_CALL(callstack) \
+  (((grpc_subchannel_call *)(callstack)) - 1)
 
 static grpc_subchannel_call *create_call(grpc_exec_ctx *exec_ctx,
-                                         connection *con);
+                                         connection *con,
+                                         grpc_pollset *pollset);
 static void connectivity_state_changed_locked(grpc_exec_ctx *exec_ctx,
                                               grpc_subchannel *c,
                                               const char *reason);
@@ -163,7 +168,7 @@ static grpc_subchannel *connection_unref_locked(
     connection *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) GRPC_MUST_USE_RESULT;
 static void subchannel_destroy(grpc_exec_ctx *exec_ctx, grpc_subchannel *c);
 
-#ifdef GRPC_SUBCHANNEL_REFCOUNT_DEBUG
+#ifdef GRPC_STREAM_REFCOUNT_DEBUG
 #define SUBCHANNEL_REF_LOCKED(p, r) \
   subchannel_ref_locked((p), __FILE__, __LINE__, (r))
 #define SUBCHANNEL_UNREF_LOCKED(p, r) \
@@ -173,6 +178,7 @@ static void subchannel_destroy(grpc_exec_ctx *exec_ctx, grpc_subchannel *c);
 #define CONNECTION_UNREF_LOCKED(cl, p, r) \
   connection_unref_locked((cl), (p), __FILE__, __LINE__, (r))
 #define REF_PASS_ARGS , file, line, reason
+#define REF_PASS_REASON , reason
 #define REF_LOG(name, p)                                                  \
   gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "%s: %p   ref %d -> %d %s", \
           (name), (p), (p)->refs, (p)->refs + 1, reason)
@@ -185,6 +191,7 @@ static void subchannel_destroy(grpc_exec_ctx *exec_ctx, grpc_subchannel *c);
 #define CONNECTION_REF_LOCKED(p, r) connection_ref_locked((p))
 #define CONNECTION_UNREF_LOCKED(cl, p, r) connection_unref_locked((cl), (p))
 #define REF_PASS_ARGS
+#define REF_PASS_REASON
 #define REF_LOG(name, p) \
   do {                   \
   } while (0)
@@ -261,7 +268,7 @@ static void subchannel_destroy(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
   gpr_free((void *)c->filters);
   grpc_channel_args_destroy(c->args);
   gpr_free(c->addr);
-  grpc_mdctx_unref(c->mdctx);
+  gpr_slice_unref(c->initial_connect_string);
   grpc_connectivity_state_destroy(exec_ctx, &c->state_tracker);
   grpc_connector_unref(exec_ctx, c->connector);
   gpr_free(c);
@@ -299,12 +306,12 @@ grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
   c->addr = gpr_malloc(args->addr_len);
   memcpy(c->addr, args->addr, args->addr_len);
   c->addr_len = args->addr_len;
+  grpc_set_initial_connect_string(&c->addr, &c->addr_len,
+                                  &c->initial_connect_string);
   c->args = grpc_channel_args_copy(args->args);
-  c->mdctx = args->mdctx;
   c->master = args->master;
   c->pollset_set = grpc_client_channel_get_connecting_pollset_set(parent_elem);
   c->random = random_seed();
-  grpc_mdctx_ref(c->mdctx);
   grpc_closure_init(&c->connected, subchannel_connected, c);
   grpc_connectivity_state_init(&c->state_tracker, GRPC_CHANNEL_IDLE,
                                "subchannel");
@@ -312,9 +319,9 @@ grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
   return c;
 }
 
-void grpc_subchannel_cancel_waiting_call(grpc_exec_ctx *exec_ctx,
-                                         grpc_subchannel *subchannel,
-                                         int iomgr_success) {
+static void cancel_waiting_calls(grpc_exec_ctx *exec_ctx,
+                                 grpc_subchannel *subchannel,
+                                 int iomgr_success) {
   waiting_for_connect *w4c;
   gpr_mu_lock(&subchannel->mu);
   w4c = subchannel->waiting;
@@ -335,6 +342,37 @@ void grpc_subchannel_cancel_waiting_call(grpc_exec_ctx *exec_ctx,
   }
 }
 
+void grpc_subchannel_cancel_create_call(grpc_exec_ctx *exec_ctx,
+                                        grpc_subchannel *subchannel,
+                                        gpr_atm *target) {
+  waiting_for_connect *w4c;
+  int unref_count = 0;
+  gpr_mu_lock(&subchannel->mu);
+  w4c = subchannel->waiting;
+  subchannel->waiting = NULL;
+  while (w4c != NULL) {
+    waiting_for_connect *next = w4c->next;
+    if (w4c->target == target) {
+      grpc_subchannel_del_interested_party(exec_ctx, w4c->subchannel,
+                                           w4c->pollset);
+      grpc_exec_ctx_enqueue(exec_ctx, w4c->notify, 0);
+
+      unref_count++;
+      gpr_free(w4c);
+    } else {
+      w4c->next = subchannel->waiting;
+      subchannel->waiting = w4c;
+    }
+
+    w4c = next;
+  }
+  gpr_mu_unlock(&subchannel->mu);
+
+  while (unref_count-- > 0) {
+    GRPC_SUBCHANNEL_UNREF(exec_ctx, subchannel, "waiting_for_connect");
+  }
+}
+
 static void continue_connect(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
   grpc_connect_in_args args;
 
@@ -343,6 +381,7 @@ static void continue_connect(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
   args.addr_len = c->addr_len;
   args.deadline = compute_connect_deadline(c);
   args.channel_args = c->args;
+  args.initial_connect_string = c->initial_connect_string;
 
   grpc_connector_connect(exec_ctx, c->connector, &args, &c->connecting_result,
                          &c->connected);
@@ -358,29 +397,35 @@ static void start_connect(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
 
 static void continue_creating_call(grpc_exec_ctx *exec_ctx, void *arg,
                                    int iomgr_success) {
-  grpc_subchannel_call_create_status call_creation_status;
+  int call_creation_finished_ok;
   waiting_for_connect *w4c = arg;
   grpc_subchannel_del_interested_party(exec_ctx, w4c->subchannel, w4c->pollset);
-  call_creation_status = grpc_subchannel_create_call(
+  call_creation_finished_ok = grpc_subchannel_create_call(
       exec_ctx, w4c->subchannel, w4c->pollset, w4c->target, w4c->notify);
-  GPR_ASSERT(call_creation_status == GRPC_SUBCHANNEL_CALL_CREATE_READY);
+  GPR_ASSERT(call_creation_finished_ok == 1);
   w4c->notify->cb(exec_ctx, w4c->notify->cb_arg, iomgr_success);
   GRPC_SUBCHANNEL_UNREF(exec_ctx, w4c->subchannel, "waiting_for_connect");
   gpr_free(w4c);
 }
 
-grpc_subchannel_call_create_status grpc_subchannel_create_call(
-    grpc_exec_ctx *exec_ctx, grpc_subchannel *c, grpc_pollset *pollset,
-    grpc_subchannel_call **target, grpc_closure *notify) {
+int grpc_subchannel_create_call(grpc_exec_ctx *exec_ctx, grpc_subchannel *c,
+                                grpc_pollset *pollset, gpr_atm *target,
+                                grpc_closure *notify) {
   connection *con;
+  grpc_subchannel_call *call;
+  GPR_TIMER_BEGIN("grpc_subchannel_create_call", 0);
   gpr_mu_lock(&c->mu);
   if (c->active != NULL) {
     con = c->active;
     CONNECTION_REF_LOCKED(con, "call");
     gpr_mu_unlock(&c->mu);
 
-    *target = create_call(exec_ctx, con);
-    return GRPC_SUBCHANNEL_CALL_CREATE_READY;
+    call = create_call(exec_ctx, con, pollset);
+    if (!gpr_atm_rel_cas(target, 0, (gpr_atm)(gpr_uintptr)call)) {
+      GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, call, "failed to set");
+    }
+    GPR_TIMER_END("grpc_subchannel_create_call", 0);
+    return 1;
   } else {
     waiting_for_connect *w4c = gpr_malloc(sizeof(*w4c));
     w4c->next = c->waiting;
@@ -405,7 +450,8 @@ grpc_subchannel_call_create_status grpc_subchannel_create_call(
     } else {
       gpr_mu_unlock(&c->mu);
     }
-    return GRPC_SUBCHANNEL_CALL_CREATE_PENDING;
+    GPR_TIMER_END("grpc_subchannel_create_call", 0);
+    return 0;
   }
 }
 
@@ -580,7 +626,7 @@ static void publish_transport(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
   con->refs = 0;
   con->subchannel = c;
   grpc_channel_stack_init(exec_ctx, filters, num_filters, c->master, c->args,
-                          c->mdctx, stk);
+                          stk);
   grpc_connected_channel_bind_transport(stk, c->connecting_result.transport);
   gpr_free((void *)c->connecting_result.filters);
   memset(&c->connecting_result, 0, sizeof(c->connecting_result));
@@ -653,10 +699,25 @@ static double generate_uniform_random_number(grpc_subchannel *c) {
 
 /* Update backoff_delta and next_attempt in subchannel */
 static void update_reconnect_parameters(grpc_subchannel *c) {
+  size_t i;
   gpr_int32 backoff_delta_millis, jitter;
   gpr_int32 max_backoff_millis =
       GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS * 1000;
   double jitter_range;
+
+  if (c->args) {
+    for (i = 0; i < c->args->num_args; i++) {
+      if (0 == strcmp(c->args->args[i].key,
+                      "grpc.testing.fixed_reconnect_backoff")) {
+        GPR_ASSERT(c->args->args[i].type == GRPC_ARG_INTEGER);
+        c->next_attempt = gpr_time_add(
+            gpr_now(GPR_CLOCK_MONOTONIC),
+            gpr_time_from_millis(c->args->args[i].value.integer, GPR_TIMESPAN));
+        return;
+      }
+    }
+  }
+
   backoff_delta_millis =
       (gpr_int32)(gpr_time_to_millis(c->backoff_delta) *
                   GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER);
@@ -687,7 +748,7 @@ static void on_alarm(grpc_exec_ctx *exec_ctx, void *arg, int iomgr_success) {
     update_reconnect_parameters(c);
     continue_connect(exec_ctx, c);
   } else {
-    grpc_subchannel_cancel_waiting_call(exec_ctx, c, iomgr_success);
+    cancel_waiting_calls(exec_ctx, c, iomgr_success);
     GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, c->master, "connecting");
     GRPC_SUBCHANNEL_UNREF(exec_ctx, c, "connecting");
   }
@@ -747,26 +808,40 @@ static void connectivity_state_changed_locked(grpc_exec_ctx *exec_ctx,
  * grpc_subchannel_call implementation
  */
 
+static void subchannel_call_destroy(grpc_exec_ctx *exec_ctx, void *call,
+                                    int success) {
+  grpc_subchannel_call *c = call;
+  gpr_mu *mu = &c->connection->subchannel->mu;
+  grpc_subchannel *destroy;
+  GPR_TIMER_BEGIN("grpc_subchannel_call_unref.destroy", 0);
+  grpc_call_stack_destroy(exec_ctx, SUBCHANNEL_CALL_TO_CALL_STACK(c));
+  gpr_mu_lock(mu);
+  destroy = CONNECTION_UNREF_LOCKED(exec_ctx, c->connection, "call");
+  gpr_mu_unlock(mu);
+  gpr_free(c);
+  if (destroy != NULL) {
+    subchannel_destroy(exec_ctx, destroy);
+  }
+  GPR_TIMER_END("grpc_subchannel_call_unref.destroy", 0);
+}
+
 void grpc_subchannel_call_ref(grpc_subchannel_call *c
                                   GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
-  gpr_ref(&c->refs);
+#ifdef GRPC_STREAM_REFCOUNT_DEBUG
+  grpc_call_stack_ref(SUBCHANNEL_CALL_TO_CALL_STACK(c), reason);
+#else
+  grpc_call_stack_ref(SUBCHANNEL_CALL_TO_CALL_STACK(c));
+#endif
 }
 
 void grpc_subchannel_call_unref(grpc_exec_ctx *exec_ctx,
                                 grpc_subchannel_call *c
                                     GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
-  if (gpr_unref(&c->refs)) {
-    gpr_mu *mu = &c->connection->subchannel->mu;
-    grpc_subchannel *destroy;
-    grpc_call_stack_destroy(exec_ctx, SUBCHANNEL_CALL_TO_CALL_STACK(c));
-    gpr_mu_lock(mu);
-    destroy = CONNECTION_UNREF_LOCKED(exec_ctx, c->connection, "call");
-    gpr_mu_unlock(mu);
-    gpr_free(c);
-    if (destroy != NULL) {
-      subchannel_destroy(exec_ctx, destroy);
-    }
-  }
+#ifdef GRPC_STREAM_REFCOUNT_DEBUG
+  grpc_call_stack_unref(exec_ctx, SUBCHANNEL_CALL_TO_CALL_STACK(c), reason);
+#else
+  grpc_call_stack_unref(exec_ctx, SUBCHANNEL_CALL_TO_CALL_STACK(c));
+#endif
 }
 
 char *grpc_subchannel_call_get_peer(grpc_exec_ctx *exec_ctx,
@@ -785,21 +860,24 @@ void grpc_subchannel_call_process_op(grpc_exec_ctx *exec_ctx,
 }
 
 static grpc_subchannel_call *create_call(grpc_exec_ctx *exec_ctx,
-                                         connection *con) {
+                                         connection *con,
+                                         grpc_pollset *pollset) {
   grpc_channel_stack *chanstk = CHANNEL_STACK_FROM_CONNECTION(con);
   grpc_subchannel_call *call =
       gpr_malloc(sizeof(grpc_subchannel_call) + chanstk->call_stack_size);
   grpc_call_stack *callstk = SUBCHANNEL_CALL_TO_CALL_STACK(call);
   call->connection = con;
-  gpr_ref_init(&call->refs, 1);
-  grpc_call_stack_init(exec_ctx, chanstk, NULL, NULL, callstk);
+  grpc_call_stack_init(exec_ctx, chanstk, 1, subchannel_call_destroy, call,
+                       NULL, NULL, callstk);
+  grpc_call_stack_set_pollset(exec_ctx, callstk, pollset);
   return call;
 }
 
-grpc_mdctx *grpc_subchannel_get_mdctx(grpc_subchannel *subchannel) {
-  return subchannel->mdctx;
-}
-
 grpc_channel *grpc_subchannel_get_master(grpc_subchannel *subchannel) {
   return subchannel->master;
 }
+
+grpc_call_stack *grpc_subchannel_call_get_call_stack(
+    grpc_subchannel_call *subchannel_call) {
+  return SUBCHANNEL_CALL_TO_CALL_STACK(subchannel_call);
+}

src/core/client_config/subchannel.h

@@ -44,7 +44,7 @@ typedef struct grpc_subchannel grpc_subchannel;
 typedef struct grpc_subchannel_call grpc_subchannel_call;
 typedef struct grpc_subchannel_args grpc_subchannel_args;
 
-#ifdef GRPC_SUBCHANNEL_REFCOUNT_DEBUG
+#ifdef GRPC_STREAM_REFCOUNT_DEBUG
 #define GRPC_SUBCHANNEL_REF(p, r) \
   grpc_subchannel_ref((p), __FILE__, __LINE__, (r))
 #define GRPC_SUBCHANNEL_UNREF(cl, p, r) \
@@ -75,27 +75,22 @@ void grpc_subchannel_call_unref(grpc_exec_ctx *exec_ctx,
                                 grpc_subchannel_call *call
                                     GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
 
-typedef enum {
-  GRPC_SUBCHANNEL_CALL_CREATE_READY,
-  GRPC_SUBCHANNEL_CALL_CREATE_PENDING
-} grpc_subchannel_call_create_status;
-
 /** construct a subchannel call (possibly asynchronously).
  *
- * If the returned status is \a GRPC_SUBCHANNEL_CALL_CREATE_READY, the call will
- * return immediately and \a target will point to a connected \a subchannel_call
- * instance. Note that \a notify will \em not be invoked in this case.
- * Otherwise, if the returned status is GRPC_SUBCHANNEL_CALL_CREATE_PENDING, the
- * subchannel call will be created asynchronously, invoking the \a notify
- * callback upon completion. */
-grpc_subchannel_call_create_status grpc_subchannel_create_call(
-    grpc_exec_ctx *exec_ctx, grpc_subchannel *subchannel, grpc_pollset *pollset,
-    grpc_subchannel_call **target, grpc_closure *notify);
+ * If the returned status is 1, the call will return immediately and \a target
+ * will point to a connected \a subchannel_call instance. Note that \a notify
+ * will \em not be invoked in this case.
+ * Otherwise, if the returned status is 0, the subchannel call will be created
+ * asynchronously, invoking the \a notify callback upon completion. */
+int grpc_subchannel_create_call(grpc_exec_ctx *exec_ctx,
+                                grpc_subchannel *subchannel,
+                                grpc_pollset *pollset, gpr_atm *target,
+                                grpc_closure *notify);
 
 /** cancel \a call in the waiting state. */
-void grpc_subchannel_cancel_waiting_call(grpc_exec_ctx *exec_ctx,
-                                         grpc_subchannel *subchannel,
-                                         int iomgr_success);
+void grpc_subchannel_cancel_create_call(grpc_exec_ctx *exec_ctx,
+                                        grpc_subchannel *subchannel,
+                                        gpr_atm *target);
 
 /** process a transport level op */
 void grpc_subchannel_process_transport_op(grpc_exec_ctx *exec_ctx,
@@ -138,6 +133,9 @@ void grpc_subchannel_call_process_op(grpc_exec_ctx *exec_ctx,
 char *grpc_subchannel_call_get_peer(grpc_exec_ctx *exec_ctx,
                                     grpc_subchannel_call *subchannel_call);
 
+grpc_call_stack *grpc_subchannel_call_get_call_stack(
+    grpc_subchannel_call *subchannel_call);
+
 struct grpc_subchannel_args {
   /** Channel filters for this channel - wrapped factories will likely
       want to mutate this */
@@ -149,8 +147,6 @@ struct grpc_subchannel_args {
   /** Address to connect to */
   struct sockaddr *addr;
   size_t addr_len;
-  /** metadata context to use */
-  grpc_mdctx *mdctx;
   /** master channel */
   grpc_channel *master;
 };
@@ -159,9 +155,6 @@ struct grpc_subchannel_args {
 grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
                                         grpc_subchannel_args *args);
 
-/** Return the metadata context associated with the subchannel */
-grpc_mdctx *grpc_subchannel_get_mdctx(grpc_subchannel *subchannel);
-
 /** Return the master channel associated with the subchannel */
 grpc_channel *grpc_subchannel_get_master(grpc_subchannel *subchannel);
 

src/core/compression/algorithm.c

@@ -37,7 +37,9 @@
 #include <grpc/compression.h>
 #include <grpc/support/useful.h>
 
+#include "src/core/compression/algorithm_metadata.h"
 #include "src/core/surface/api_trace.h"
+#include "src/core/transport/static_metadata.h"
 
 int grpc_compression_algorithm_parse(const char *name, size_t name_length,
                                      grpc_compression_algorithm *algorithm) {
@@ -72,17 +74,55 @@ int grpc_compression_algorithm_name(grpc_compression_algorithm algorithm,
   switch (algorithm) {
     case GRPC_COMPRESS_NONE:
       *name = "identity";
-      break;
+      return 1;
     case GRPC_COMPRESS_DEFLATE:
       *name = "deflate";
-      break;
+      return 1;
     case GRPC_COMPRESS_GZIP:
       *name = "gzip";
-      break;
-    default:
+      return 1;
+    case GRPC_COMPRESS_ALGORITHMS_COUNT:
       return 0;
   }
-  return 1;
+  return 0;
+}
+
+grpc_compression_algorithm grpc_compression_algorithm_from_mdstr(
+    grpc_mdstr *str) {
+  if (str == GRPC_MDSTR_IDENTITY) return GRPC_COMPRESS_NONE;
+  if (str == GRPC_MDSTR_DEFLATE) return GRPC_COMPRESS_DEFLATE;
+  if (str == GRPC_MDSTR_GZIP) return GRPC_COMPRESS_GZIP;
+  return GRPC_COMPRESS_ALGORITHMS_COUNT;
+}
+
+grpc_mdstr *grpc_compression_algorithm_mdstr(
+    grpc_compression_algorithm algorithm) {
+  switch (algorithm) {
+    case GRPC_COMPRESS_NONE:
+      return GRPC_MDSTR_IDENTITY;
+    case GRPC_COMPRESS_DEFLATE:
+      return GRPC_MDSTR_DEFLATE;
+    case GRPC_COMPRESS_GZIP:
+      return GRPC_MDSTR_GZIP;
+    case GRPC_COMPRESS_ALGORITHMS_COUNT:
+      return NULL;
+  }
+  return NULL;
+}
+
+grpc_mdelem *grpc_compression_encoding_mdelem(
+    grpc_compression_algorithm algorithm) {
+  switch (algorithm) {
+    case GRPC_COMPRESS_NONE:
+      return GRPC_MDELEM_GRPC_ENCODING_IDENTITY;
+    case GRPC_COMPRESS_DEFLATE:
+      return GRPC_MDELEM_GRPC_ENCODING_DEFLATE;
+    case GRPC_COMPRESS_GZIP:
+      return GRPC_MDELEM_GRPC_ENCODING_GZIP;
+    case GRPC_COMPRESS_ALGORITHMS_COUNT:
+      return NULL;
+  }
+  return NULL;
 }
 
 /* TODO(dgq): Add the ability to specify parameters to the individual

src/core/compression/algorithm_metadata.h

@@ -0,0 +1,53 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_COMPRESSION_ALGORITHM_METADATA_H
+#define GRPC_INTERNAL_CORE_COMPRESSION_ALGORITHM_METADATA_H
+
+#include <grpc/compression.h>
+#include "src/core/transport/metadata.h"
+
+/** Return compression algorithm based metadata value */
+grpc_mdstr *grpc_compression_algorithm_mdstr(
+    grpc_compression_algorithm algorithm);
+
+/** Return compression algorithm based metadata element (grpc-encoding: xxx) */
+grpc_mdelem *grpc_compression_encoding_mdelem(
+    grpc_compression_algorithm algorithm);
+
+/** Find compression algorithm based on passed in mdstr - returns
+ * GRPC_COMPRESS_ALGORITHM_COUNT on failure */
+grpc_compression_algorithm grpc_compression_algorithm_from_mdstr(
+    grpc_mdstr *str);
+
+#endif /* GRPC_INTERNAL_CORE_COMPRESSION_ALGORITHM_METADATA_H */

src/core/iomgr/closure.c

@@ -39,18 +39,17 @@ void grpc_closure_init(grpc_closure *closure, grpc_iomgr_cb_func cb,
                        void *cb_arg) {
   closure->cb = cb;
   closure->cb_arg = cb_arg;
-  closure->next = NULL;
+  closure->final_data = 0;
 }
 
 void grpc_closure_list_add(grpc_closure_list *closure_list,
                            grpc_closure *closure, int success) {
   if (closure == NULL) return;
-  closure->next = NULL;
-  closure->success = success;
+  closure->final_data = (success != 0);
   if (closure_list->head == NULL) {
     closure_list->head = closure;
   } else {
-    closure_list->tail->next = closure;
+    closure_list->tail->final_data |= (gpr_uintptr)closure;
   }
   closure_list->tail = closure;
 }
@@ -66,22 +65,12 @@ void grpc_closure_list_move(grpc_closure_list *src, grpc_closure_list *dst) {
   if (dst->head == NULL) {
     *dst = *src;
   } else {
-    dst->tail->next = src->head;
+    dst->tail->final_data |= (gpr_uintptr)src->head;
     dst->tail = src->tail;
   }
   src->head = src->tail = NULL;
 }
 
-grpc_closure *grpc_closure_list_pop(grpc_closure_list *list) {
-  grpc_closure *head;
-  if (list->head == NULL) {
-    return NULL;
-  }
-  head = list->head;
-  list->head = list->head->next;
-  return head;
-}
-
 typedef struct {
   grpc_iomgr_cb_func cb;
   void *cb_arg;
@@ -103,3 +92,7 @@ grpc_closure *grpc_closure_create(grpc_iomgr_cb_func cb, void *cb_arg) {
   grpc_closure_init(&wc->wrapper, closure_wrapper, wc);
   return &wc->wrapper;
 }
+
+grpc_closure *grpc_closure_next(grpc_closure *closure) {
+  return (grpc_closure *)(closure->final_data & ~(gpr_uintptr)1);
+}

src/core/iomgr/closure.h

@@ -34,7 +34,7 @@
 #ifndef GRPC_INTERNAL_CORE_IOMGR_CLOSURE_H
 #define GRPC_INTERNAL_CORE_IOMGR_CLOSURE_H
 
-#include <stddef.h>
+#include <grpc/support/port_platform.h>
 
 struct grpc_closure;
 typedef struct grpc_closure grpc_closure;
@@ -64,13 +64,10 @@ struct grpc_closure {
   /** Arguments to be passed to "cb". */
   void *cb_arg;
 
-  /** Internal. A boolean indication to "cb" on the state of the iomgr.
-   * For instance, closures created during a shutdown would have this field set
-   * to false. */
-  int success;
-
-  /**< Internal. Do not touch */
-  struct grpc_closure *next;
+  /** Once enqueued, contains in the lower bit the success of the closure,
+      and in the upper bits the pointer to the next closure in the list.
+      Before enqueing for execution, this is usable for scratch data. */
+  gpr_uintptr final_data;
 };
 
 /** Initializes \a closure with \a cb and \a cb_arg. */
@@ -91,10 +88,10 @@ void grpc_closure_list_add(grpc_closure_list *list, grpc_closure *closure,
 /** append all closures from \a src to \a dst and empty \a src. */
 void grpc_closure_list_move(grpc_closure_list *src, grpc_closure_list *dst);
 
-/** pop (return and remove) the head closure from \a list. */
-grpc_closure *grpc_closure_list_pop(grpc_closure_list *list);
-
 /** return whether \a list is empty. */
 int grpc_closure_list_empty(grpc_closure_list list);
 
+/** return the next pointer for a queued closure list */
+grpc_closure *grpc_closure_next(grpc_closure *closure);
+
 #endif /* GRPC_INTERNAL_CORE_IOMGR_CLOSURE_H */

src/core/iomgr/exec_ctx.c

@@ -44,10 +44,11 @@ int grpc_exec_ctx_flush(grpc_exec_ctx *exec_ctx) {
     grpc_closure *c = exec_ctx->closure_list.head;
     exec_ctx->closure_list.head = exec_ctx->closure_list.tail = NULL;
     while (c != NULL) {
-      grpc_closure *next = c->next;
+      int success = (int)(c->final_data & 1);
+      grpc_closure *next = (grpc_closure *)(c->final_data & ~(gpr_uintptr)1);
       did_something++;
       GPR_TIMER_BEGIN("grpc_exec_ctx_flush.cb", 0);
-      c->cb(exec_ctx, c->cb_arg, c->success);
+      c->cb(exec_ctx, c->cb_arg, success);
       GPR_TIMER_END("grpc_exec_ctx_flush.cb", 0);
       c = next;
     }

src/core/iomgr/executor.c

@@ -63,8 +63,6 @@ void grpc_executor_init() {
 
 /* thread body */
 static void closure_exec_thread_func(void *ignored) {
-  grpc_closure *closure;
-
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (1) {
     gpr_mu_lock(&g_executor.mu);
@@ -72,16 +70,16 @@ static void closure_exec_thread_func(void *ignored) {
       gpr_mu_unlock(&g_executor.mu);
       break;
     }
-    closure = grpc_closure_list_pop(&g_executor.closures);
-    if (closure == NULL) {
+    if (grpc_closure_list_empty(g_executor.closures)) {
       /* no more work, time to die */
       GPR_ASSERT(g_executor.busy == 1);
       g_executor.busy = 0;
       gpr_mu_unlock(&g_executor.mu);
       break;
+    } else {
+      grpc_exec_ctx_enqueue_list(&exec_ctx, &g_executor.closures);
     }
     gpr_mu_unlock(&g_executor.mu);
-    closure->cb(&exec_ctx, closure->cb_arg, closure->success);
     grpc_exec_ctx_flush(&exec_ctx);
   }
   grpc_exec_ctx_finish(&exec_ctx);
@@ -125,7 +123,6 @@ void grpc_executor_enqueue(grpc_closure *closure, int success) {
 
 void grpc_executor_shutdown() {
   int pending_join;
-  grpc_closure *closure;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
   gpr_mu_lock(&g_executor.mu);
@@ -136,9 +133,7 @@ void grpc_executor_shutdown() {
    * list below because we aren't accepting new work */
 
   /* Execute pending callbacks, some may be performing cleanups */
-  while ((closure = grpc_closure_list_pop(&g_executor.closures)) != NULL) {
-    closure->cb(&exec_ctx, closure->cb_arg, closure->success);
-  }
+  grpc_exec_ctx_enqueue_list(&exec_ctx, &g_executor.closures);
   grpc_exec_ctx_finish(&exec_ctx);
   GPR_ASSERT(grpc_closure_list_empty(g_executor.closures));
   if (pending_join) {

src/core/iomgr/fd_posix.c

@@ -207,14 +207,21 @@ static int has_watchers(grpc_fd *fd) {
 }
 
 void grpc_fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
-                    const char *reason) {
+                    int *release_fd, const char *reason) {
   fd->on_done_closure = on_done;
-  shutdown(fd->fd, SHUT_RDWR);
+  fd->released = release_fd != NULL;
+  if (!fd->released) {
+    shutdown(fd->fd, SHUT_RDWR);
+  } else {
+    *release_fd = fd->fd;
+  }
   gpr_mu_lock(&fd->mu);
   REF_BY(fd, 1, reason); /* remove active status, but keep referenced */
   if (!has_watchers(fd)) {
     fd->closed = 1;
-    close(fd->fd);
+    if (!fd->released) {
+      close(fd->fd);
+    }
     grpc_exec_ctx_enqueue(exec_ctx, fd->on_done_closure, 1);
   } else {
     wake_all_watchers_locked(fd);
@@ -406,7 +413,9 @@ void grpc_fd_end_poll(grpc_exec_ctx *exec_ctx, grpc_fd_watcher *watcher,
   }
   if (grpc_fd_is_orphaned(fd) && !has_watchers(fd) && !fd->closed) {
     fd->closed = 1;
-    close(fd->fd);
+    if (!fd->released) {
+      close(fd->fd);
+    }
     grpc_exec_ctx_enqueue(exec_ctx, fd->on_done_closure, 1);
   }
   gpr_mu_unlock(&fd->mu);

src/core/iomgr/fd_posix.h

@@ -62,6 +62,7 @@ struct grpc_fd {
   gpr_mu mu;
   int shutdown;
   int closed;
+  int released;
 
   /* The watcher list.
 
@@ -107,11 +108,12 @@ grpc_fd *grpc_fd_create(int fd, const char *name);
 /* Releases fd to be asynchronously destroyed.
    on_done is called when the underlying file descriptor is definitely close()d.
    If on_done is NULL, no callback will be made.
+   If release_fd is not NULL, it's set to fd and fd will not be closed.
    Requires: *fd initialized; no outstanding notify_on_read or
    notify_on_write.
    MUST NOT be called with a pollset lock taken */
 void grpc_fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
-                    const char *reason);
+                    int *release_fd, const char *reason);
 
 /* Begin polling on an fd.
    Registers that the given pollset is interested in this fd - so that if read

src/core/iomgr/pollset.h

@@ -55,8 +55,13 @@
 #endif
 
 void grpc_pollset_init(grpc_pollset *pollset);
+/* Begin shutting down the pollset, and call closure when done.
+ * GRPC_POLLSET_MU(pollset) must be held */
 void grpc_pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                            grpc_closure *closure);
+/** Reset the pollset to its initial state (perhaps with some cached objects);
+ *  must have been previously shutdown */
+void grpc_pollset_reset(grpc_pollset *pollset);
 void grpc_pollset_destroy(grpc_pollset *pollset);
 
 /* Do some work on a pollset.

src/core/iomgr/pollset_multipoller_with_epoll.c

@@ -47,21 +47,13 @@
 #include "src/core/support/block_annotate.h"
 #include "src/core/profiling/timers.h"
 
-typedef struct wakeup_fd_hdl {
-  grpc_wakeup_fd wakeup_fd;
-  struct wakeup_fd_hdl *next;
-} wakeup_fd_hdl;
-
 typedef struct {
   grpc_pollset *pollset;
   grpc_fd *fd;
   grpc_closure closure;
 } delayed_add;
 
-typedef struct {
-  int epoll_fd;
-  wakeup_fd_hdl *free_wakeup_fds;
-} pollset_hdr;
+typedef struct { int epoll_fd; } pollset_hdr;
 
 static void finally_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                            grpc_fd *fd) {
@@ -174,7 +166,7 @@ static void multipoll_with_epoll_pollset_maybe_work_and_unlock(
 
   timeout_ms = grpc_poll_deadline_to_millis_timeout(deadline, now);
 
-  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd);
+  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
   pfds[0].events = POLLIN;
   pfds[0].revents = 0;
   pfds[1].fd = h->epoll_fd;
@@ -197,7 +189,7 @@ static void multipoll_with_epoll_pollset_maybe_work_and_unlock(
     /* do nothing */
   } else {
     if (pfds[0].revents) {
-      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd);
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
     }
     if (pfds[1].revents) {
       do {

src/core/iomgr/pollset_multipoller_with_poll_posix.c

@@ -124,7 +124,7 @@ static void multipoll_with_poll_pollset_maybe_work_and_unlock(
   pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd);
   pfds[0].events = POLLIN;
   pfds[0].revents = 0;
-  pfds[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd);
+  pfds[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
   pfds[1].events = POLLIN;
   pfds[1].revents = 0;
   for (i = 0; i < h->fd_count; i++) {
@@ -174,7 +174,7 @@ static void multipoll_with_poll_pollset_maybe_work_and_unlock(
       grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
     }
     if (pfds[1].revents & POLLIN_CHECK) {
-      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd);
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
     }
     for (i = 2; i < pfd_count; i++) {
       if (watchers[i].fd == NULL) {

src/core/iomgr/pollset_posix.c

@@ -111,7 +111,7 @@ void grpc_pollset_kick_ext(grpc_pollset *p,
       for (specific_worker = p->root_worker.next;
            specific_worker != &p->root_worker;
            specific_worker = specific_worker->next) {
-        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd);
+        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
       }
       p->kicked_without_pollers = 1;
       GPR_TIMER_END("grpc_pollset_kick_ext.broadcast", 0);
@@ -122,14 +122,14 @@ void grpc_pollset_kick_ext(grpc_pollset *p,
         specific_worker->reevaluate_polling_on_wakeup = 1;
       }
       specific_worker->kicked_specifically = 1;
-      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd);
+      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
     } else if ((flags & GRPC_POLLSET_CAN_KICK_SELF) != 0) {
       GPR_TIMER_MARK("kick_yoself", 0);
       if ((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) != 0) {
         specific_worker->reevaluate_polling_on_wakeup = 1;
       }
       specific_worker->kicked_specifically = 1;
-      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd);
+      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
     }
   } else if (gpr_tls_get(&g_current_thread_poller) != (gpr_intptr)p) {
     GPR_ASSERT((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) == 0);
@@ -151,7 +151,7 @@ void grpc_pollset_kick_ext(grpc_pollset *p,
       if (specific_worker != NULL) {
         GPR_TIMER_MARK("finally_kick", 0);
         push_back_worker(p, specific_worker);
-        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd);
+        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
       }
     } else {
       GPR_TIMER_MARK("kicked_no_pollers", 0);
@@ -177,9 +177,9 @@ void grpc_pollset_global_init(void) {
 
 void grpc_pollset_global_shutdown(void) {
   grpc_wakeup_fd_destroy(&grpc_global_wakeup_fd);
-  grpc_wakeup_fd_global_destroy();
   gpr_tls_destroy(&g_current_thread_poller);
   gpr_tls_destroy(&g_current_thread_worker);
+  grpc_wakeup_fd_global_destroy();
 }
 
 void grpc_kick_poller(void) { grpc_wakeup_fd_wakeup(&grpc_global_wakeup_fd); }
@@ -194,7 +194,36 @@ void grpc_pollset_init(grpc_pollset *pollset) {
   pollset->in_flight_cbs = 0;
   pollset->shutting_down = 0;
   pollset->called_shutdown = 0;
+  pollset->kicked_without_pollers = 0;
   pollset->idle_jobs.head = pollset->idle_jobs.tail = NULL;
+  pollset->local_wakeup_cache = NULL;
+  pollset->kicked_without_pollers = 0;
+  become_basic_pollset(pollset, NULL);
+}
+
+void grpc_pollset_destroy(grpc_pollset *pollset) {
+  GPR_ASSERT(pollset->in_flight_cbs == 0);
+  GPR_ASSERT(!grpc_pollset_has_workers(pollset));
+  GPR_ASSERT(pollset->idle_jobs.head == pollset->idle_jobs.tail);
+  pollset->vtable->destroy(pollset);
+  gpr_mu_destroy(&pollset->mu);
+  while (pollset->local_wakeup_cache) {
+    grpc_cached_wakeup_fd *next = pollset->local_wakeup_cache->next;
+    grpc_wakeup_fd_destroy(&pollset->local_wakeup_cache->fd);
+    gpr_free(pollset->local_wakeup_cache);
+    pollset->local_wakeup_cache = next;
+  }
+}
+
+void grpc_pollset_reset(grpc_pollset *pollset) {
+  GPR_ASSERT(pollset->shutting_down);
+  GPR_ASSERT(pollset->in_flight_cbs == 0);
+  GPR_ASSERT(!grpc_pollset_has_workers(pollset));
+  GPR_ASSERT(pollset->idle_jobs.head == pollset->idle_jobs.tail);
+  pollset->vtable->destroy(pollset);
+  pollset->shutting_down = 0;
+  pollset->called_shutdown = 0;
+  pollset->kicked_without_pollers = 0;
   become_basic_pollset(pollset, NULL);
 }
 
@@ -244,13 +273,19 @@ void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
   /* this must happen before we (potentially) drop pollset->mu */
   worker->next = worker->prev = NULL;
   worker->reevaluate_polling_on_wakeup = 0;
+  if (pollset->local_wakeup_cache != NULL) {
+    worker->wakeup_fd = pollset->local_wakeup_cache;
+    pollset->local_wakeup_cache = worker->wakeup_fd->next;
+  } else {
+    worker->wakeup_fd = gpr_malloc(sizeof(*worker->wakeup_fd));
+    grpc_wakeup_fd_init(&worker->wakeup_fd->fd);
+  }
   worker->kicked_specifically = 0;
-  /* TODO(ctiller): pool these */
-  grpc_wakeup_fd_init(&worker->wakeup_fd);
   /* If there's work waiting for the pollset to be idle, and the
      pollset is idle, then do that work */
   if (!grpc_pollset_has_workers(pollset) &&
       !grpc_closure_list_empty(pollset->idle_jobs)) {
+    GPR_TIMER_MARK("grpc_pollset_work.idle_jobs", 0);
     grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs);
     goto done;
   }
@@ -259,16 +294,19 @@ void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
      May update deadline to ensure timely wakeups.
      TODO(ctiller): can this work be localized? */
   if (grpc_timer_check(exec_ctx, now, &deadline)) {
+    GPR_TIMER_MARK("grpc_pollset_work.alarm_triggered", 0);
     gpr_mu_unlock(&pollset->mu);
     locked = 0;
     goto done;
   }
   /* If we're shutting down then we don't execute any extended work */
   if (pollset->shutting_down) {
+    GPR_TIMER_MARK("grpc_pollset_work.shutting_down", 0);
     goto done;
   }
   /* Give do_promote priority so we don't starve it out */
   if (pollset->in_flight_cbs) {
+    GPR_TIMER_MARK("grpc_pollset_work.in_flight_cbs", 0);
     gpr_mu_unlock(&pollset->mu);
     locked = 0;
     goto done;
@@ -293,6 +331,7 @@ void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
       locked = 0;
       gpr_tls_set(&g_current_thread_poller, 0);
     } else {
+      GPR_TIMER_MARK("grpc_pollset_work.kicked_without_pollers", 0);
       pollset->kicked_without_pollers = 0;
     }
   /* Finished execution - start cleaning up.
@@ -323,7 +362,10 @@ void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
     remove_worker(pollset, worker);
     gpr_tls_set(&g_current_thread_worker, 0);
   }
-  grpc_wakeup_fd_destroy(&worker->wakeup_fd);
+  /* release wakeup fd to the local pool */
+  worker->wakeup_fd->next = pollset->local_wakeup_cache;
+  pollset->local_wakeup_cache = worker->wakeup_fd;
+  /* check shutdown conditions */
   if (pollset->shutting_down) {
     if (grpc_pollset_has_workers(pollset)) {
       grpc_pollset_kick(pollset, NULL);
@@ -338,8 +380,8 @@ void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
        * TODO(dklempner): Can we refactor the shutdown logic to avoid this? */
       gpr_mu_lock(&pollset->mu);
     } else if (!grpc_closure_list_empty(pollset->idle_jobs)) {
-      gpr_mu_unlock(&pollset->mu);
       grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs);
+      gpr_mu_unlock(&pollset->mu);
       grpc_exec_ctx_flush(exec_ctx);
       gpr_mu_lock(&pollset->mu);
     }
@@ -349,35 +391,20 @@ void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
 
 void grpc_pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                            grpc_closure *closure) {
-  int call_shutdown = 0;
-  gpr_mu_lock(&pollset->mu);
   GPR_ASSERT(!pollset->shutting_down);
   pollset->shutting_down = 1;
-  if (!pollset->called_shutdown && pollset->in_flight_cbs == 0 &&
-      !grpc_pollset_has_workers(pollset)) {
-    pollset->called_shutdown = 1;
-    call_shutdown = 1;
-  }
+  pollset->shutdown_done = closure;
+  grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
   if (!grpc_pollset_has_workers(pollset)) {
     grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs);
   }
-  pollset->shutdown_done = closure;
-  grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
-  gpr_mu_unlock(&pollset->mu);
-
-  if (call_shutdown) {
+  if (!pollset->called_shutdown && pollset->in_flight_cbs == 0 &&
+      !grpc_pollset_has_workers(pollset)) {
+    pollset->called_shutdown = 1;
     finish_shutdown(exec_ctx, pollset);
   }
 }
 
-void grpc_pollset_destroy(grpc_pollset *pollset) {
-  GPR_ASSERT(pollset->shutting_down);
-  GPR_ASSERT(pollset->in_flight_cbs == 0);
-  GPR_ASSERT(!grpc_pollset_has_workers(pollset));
-  pollset->vtable->destroy(pollset);
-  gpr_mu_destroy(&pollset->mu);
-}
-
 int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline,
                                          gpr_timespec now) {
   gpr_timespec timeout;
@@ -557,7 +584,7 @@ static void basic_pollset_maybe_work_and_unlock(grpc_exec_ctx *exec_ctx,
   pfd[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd);
   pfd[0].events = POLLIN;
   pfd[0].revents = 0;
-  pfd[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd);
+  pfd[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
   pfd[1].events = POLLIN;
   pfd[1].revents = 0;
   nfds = 2;
@@ -586,7 +613,9 @@ static void basic_pollset_maybe_work_and_unlock(grpc_exec_ctx *exec_ctx,
   GPR_TIMER_END("poll", 0);
 
   if (r < 0) {
-    gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
+    if (errno != EINTR) {
+      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
+    }
     if (fd) {
       grpc_fd_end_poll(exec_ctx, &fd_watcher, 0, 0);
     }
@@ -599,7 +628,7 @@ static void basic_pollset_maybe_work_and_unlock(grpc_exec_ctx *exec_ctx,
       grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
     }
     if (pfd[1].revents & POLLIN_CHECK) {
-      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd);
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
     }
     if (nfds > 2) {
       grpc_fd_end_poll(exec_ctx, &fd_watcher, pfd[2].revents & POLLIN_CHECK,

src/core/iomgr/pollset_posix.h

@@ -48,8 +48,13 @@ typedef struct grpc_pollset_vtable grpc_pollset_vtable;
    use the struct tag */
 struct grpc_fd;
 
+typedef struct grpc_cached_wakeup_fd {
+  grpc_wakeup_fd fd;
+  struct grpc_cached_wakeup_fd *next;
+} grpc_cached_wakeup_fd;
+
 typedef struct grpc_pollset_worker {
-  grpc_wakeup_fd wakeup_fd;
+  grpc_cached_wakeup_fd *wakeup_fd;
   int reevaluate_polling_on_wakeup;
   int kicked_specifically;
   struct grpc_pollset_worker *next;
@@ -74,6 +79,8 @@ typedef struct grpc_pollset {
     int fd;
     void *ptr;
   } data;
+  /* Local cache of eventfds for workers */
+  grpc_cached_wakeup_fd *local_wakeup_cache;
 } grpc_pollset;
 
 struct grpc_pollset_vtable {

src/core/iomgr/pollset_windows.c

@@ -35,6 +35,7 @@
 
 #ifdef GPR_WINSOCK_SOCKET
 
+#include <grpc/support/log.h>
 #include <grpc/support/thd.h>
 
 #include "src/core/iomgr/timer_internal.h"
@@ -112,7 +113,6 @@ void grpc_pollset_init(grpc_pollset *pollset) {
 
 void grpc_pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                            grpc_closure *closure) {
-  gpr_mu_lock(&grpc_polling_mu);
   pollset->shutting_down = 1;
   grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
   if (!pollset->is_iocp_worker) {
@@ -120,11 +120,20 @@ void grpc_pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
   } else {
     pollset->on_shutdown = closure;
   }
-  gpr_mu_unlock(&grpc_polling_mu);
 }
 
 void grpc_pollset_destroy(grpc_pollset *pollset) {}
 
+void grpc_pollset_reset(grpc_pollset *pollset) {
+  GPR_ASSERT(pollset->shutting_down);
+  GPR_ASSERT(
+      !has_workers(&pollset->root_worker, GRPC_POLLSET_WORKER_LINK_POLLSET));
+  pollset->shutting_down = 0;
+  pollset->is_iocp_worker = 0;
+  pollset->kicked_without_pollers = 0;
+  pollset->on_shutdown = NULL;
+}
+
 void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                        grpc_pollset_worker *worker, gpr_timespec now,
                        gpr_timespec deadline) {

src/core/iomgr/tcp_client_posix.c

@@ -196,7 +196,7 @@ static void on_writable(grpc_exec_ctx *exec_ctx, void *acp, int success) {
 finish:
   if (fd != NULL) {
     grpc_pollset_set_del_fd(exec_ctx, ac->interested_parties, fd);
-    grpc_fd_orphan(exec_ctx, fd, NULL, "tcp_client_orphan");
+    grpc_fd_orphan(exec_ctx, fd, NULL, NULL, "tcp_client_orphan");
     fd = NULL;
   }
   done = (--ac->refs == 0);
@@ -265,7 +265,7 @@ void grpc_tcp_client_connect(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
 
   if (errno != EWOULDBLOCK && errno != EINPROGRESS) {
     gpr_log(GPR_ERROR, "connect error to '%s': %s", addr_str, strerror(errno));
-    grpc_fd_orphan(exec_ctx, fdobj, NULL, "tcp_client_connect_error");
+    grpc_fd_orphan(exec_ctx, fdobj, NULL, NULL, "tcp_client_connect_error");
     grpc_exec_ctx_enqueue(exec_ctx, closure, 0);
     goto done;
   }

src/core/iomgr/tcp_posix.c

@@ -90,6 +90,8 @@ typedef struct {
 
   grpc_closure *read_cb;
   grpc_closure *write_cb;
+  grpc_closure *release_fd_cb;
+  int *release_fd;
 
   grpc_closure read_closure;
   grpc_closure write_closure;
@@ -108,7 +110,8 @@ static void tcp_shutdown(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep) {
 }
 
 static void tcp_free(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp) {
-  grpc_fd_orphan(exec_ctx, tcp->em_fd, NULL, "tcp_unref_orphan");
+  grpc_fd_orphan(exec_ctx, tcp->em_fd, tcp->release_fd_cb, tcp->release_fd,
+                 "tcp_unref_orphan");
   gpr_slice_buffer_destroy(&tcp->last_read_buffer);
   gpr_free(tcp->peer_string);
   gpr_free(tcp);
@@ -452,6 +455,8 @@ grpc_endpoint *grpc_tcp_create(grpc_fd *em_fd, size_t slice_size,
   tcp->fd = em_fd->fd;
   tcp->read_cb = NULL;
   tcp->write_cb = NULL;
+  tcp->release_fd_cb = NULL;
+  tcp->release_fd = NULL;
   tcp->incoming_buffer = NULL;
   tcp->slice_size = slice_size;
   tcp->iov_size = 1;
@@ -468,4 +473,13 @@ grpc_endpoint *grpc_tcp_create(grpc_fd *em_fd, size_t slice_size,
   return &tcp->base;
 }
 
+void grpc_tcp_destroy_and_release_fd(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
+                                     int *fd, grpc_closure *done) {
+  grpc_tcp *tcp = (grpc_tcp *)ep;
+  GPR_ASSERT(ep->vtable == &vtable);
+  tcp->release_fd = fd;
+  tcp->release_fd_cb = done;
+  TCP_UNREF(exec_ctx, tcp, "destroy");
+}
+
 #endif

src/core/iomgr/tcp_posix.h

@@ -56,4 +56,10 @@ extern int grpc_tcp_trace;
 grpc_endpoint *grpc_tcp_create(grpc_fd *fd, size_t read_slice_size,
                                const char *peer_string);
 
+/* Destroy the tcp endpoint without closing its fd. *fd will be set and done
+ * will be called when the endpoint is destroyed.
+ * Requires: ep must be a tcp endpoint and fd must not be NULL. */
+void grpc_tcp_destroy_and_release_fd(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
+                                     int *fd, grpc_closure *done);
+
 #endif /* GRPC_INTERNAL_CORE_IOMGR_TCP_POSIX_H */

src/core/iomgr/tcp_server.h

@@ -39,6 +39,9 @@
 /* Forward decl of grpc_tcp_server */
 typedef struct grpc_tcp_server grpc_tcp_server;
 
+/* Forward decl of grpc_tcp_listener */
+typedef struct grpc_tcp_listener grpc_tcp_listener;
+
 /* Called for newly connected TCP connections. */
 typedef void (*grpc_tcp_server_cb)(grpc_exec_ctx *exec_ctx, void *arg,
                                    grpc_endpoint *ep);
@@ -51,19 +54,17 @@ void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *server,
                            grpc_pollset **pollsets, size_t pollset_count,
                            grpc_tcp_server_cb on_accept_cb, void *cb_arg);
 
-/* Add a port to the server, returning port number on success, or negative
-   on failure.
+/* Add a port to the server, returning the newly created listener on success,
+   or a null pointer on failure.
 
    The :: and 0.0.0.0 wildcard addresses are treated identically, accepting
    both IPv4 and IPv6 connections, but :: is the preferred style.  This usually
    creates one socket, but possibly two on systems which support IPv6,
-   but not dualstack sockets.
-
-   For raw access to the underlying sockets, see grpc_tcp_server_get_fd(). */
+   but not dualstack sockets. */
 /* TODO(ctiller): deprecate this, and make grpc_tcp_server_add_ports to handle
                   all of the multiple socket port matching logic in one place */
-int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
-                             size_t addr_len);
+grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
+                                            const void *addr, size_t addr_len);
 
 /* Returns the file descriptor of the Nth listening socket on this server,
    or -1 if the index is out of bounds.
@@ -75,4 +76,8 @@ int grpc_tcp_server_get_fd(grpc_tcp_server *s, unsigned index);
 void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *server,
                              grpc_closure *closure);
 
+int grpc_tcp_listener_get_port(grpc_tcp_listener *listener);
+void grpc_tcp_listener_ref(grpc_tcp_listener *listener);
+void grpc_tcp_listener_unref(grpc_tcp_listener *listener);
+
 #endif /* GRPC_INTERNAL_CORE_IOMGR_TCP_SERVER_H */

src/core/iomgr/tcp_server_posix.c

@@ -67,14 +67,13 @@
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
 
-#define INIT_PORT_CAP 2
 #define MIN_SAFE_ACCEPT_QUEUE_SIZE 100
 
 static gpr_once s_init_max_accept_queue_size;
 static int s_max_accept_queue_size;
 
 /* one listening port */
-typedef struct {
+struct grpc_tcp_listener {
   int fd;
   grpc_fd *emfd;
   grpc_tcp_server *server;
@@ -84,9 +83,18 @@ typedef struct {
     struct sockaddr_un un;
   } addr;
   size_t addr_len;
+  int port;
   grpc_closure read_closure;
   grpc_closure destroyed_closure;
-} server_port;
+  gpr_refcount refs;
+  struct grpc_tcp_listener *next;
+  /* When we add a listener, more than one can be created, mainly because of
+     IPv6. A sibling will still be in the normal list, but will be flagged
+     as such. Any action, such as ref or unref, will affect all of the
+     siblings in the list. */
+  struct grpc_tcp_listener *sibling;
+  int is_sibling;
+};
 
 static void unlink_if_unix_domain_socket(const struct sockaddr_un *un) {
   struct stat st;
@@ -112,10 +120,9 @@ struct grpc_tcp_server {
   /* is this server shutting down? (boolean) */
   int shutdown;
 
-  /* all listening ports */
-  server_port *ports;
-  size_t nports;
-  size_t port_capacity;
+  /* linked list of server ports */
+  grpc_tcp_listener *head;
+  unsigned nports;
 
   /* shutdown callback */
   grpc_closure *shutdown_complete;
@@ -134,9 +141,8 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
   s->shutdown = 0;
   s->on_accept_cb = NULL;
   s->on_accept_cb_arg = NULL;
-  s->ports = gpr_malloc(sizeof(server_port) * INIT_PORT_CAP);
+  s->head = NULL;
   s->nports = 0;
-  s->port_capacity = INIT_PORT_CAP;
   return s;
 }
 
@@ -145,7 +151,12 @@ static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
 
   gpr_mu_destroy(&s->mu);
 
-  gpr_free(s->ports);
+  while (s->head) {
+    grpc_tcp_listener *sp = s->head;
+    s->head = sp->next;
+    grpc_tcp_listener_unref(sp);
+  }
+
   gpr_free(s);
 }
 
@@ -166,8 +177,6 @@ static void destroyed_port(grpc_exec_ctx *exec_ctx, void *server, int success) {
    events will be received on them - at this point it's safe to destroy
    things */
 static void deactivated_all_ports(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
-  size_t i;
-
   /* delete ALL the things */
   gpr_mu_lock(&s->mu);
 
@@ -176,15 +185,15 @@ static void deactivated_all_ports(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
     return;
   }
 
-  if (s->nports) {
-    for (i = 0; i < s->nports; i++) {
-      server_port *sp = &s->ports[i];
+  if (s->head) {
+    grpc_tcp_listener *sp;
+    for (sp = s->head; sp; sp = sp->next) {
       if (sp->addr.sockaddr.sa_family == AF_UNIX) {
         unlink_if_unix_domain_socket(&sp->addr.un);
       }
       sp->destroyed_closure.cb = destroyed_port;
       sp->destroyed_closure.cb_arg = s;
-      grpc_fd_orphan(exec_ctx, sp->emfd, &sp->destroyed_closure,
+      grpc_fd_orphan(exec_ctx, sp->emfd, &sp->destroyed_closure, NULL,
                      "tcp_listener_shutdown");
     }
     gpr_mu_unlock(&s->mu);
@@ -196,7 +205,6 @@ static void deactivated_all_ports(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
 
 void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                              grpc_closure *closure) {
-  size_t i;
   gpr_mu_lock(&s->mu);
 
   GPR_ASSERT(!s->shutdown);
@@ -206,8 +214,9 @@ void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
 
   /* shutdown all fd's */
   if (s->active_ports) {
-    for (i = 0; i < s->nports; i++) {
-      grpc_fd_shutdown(exec_ctx, s->ports[i].emfd);
+    grpc_tcp_listener *sp;
+    for (sp = s->head; sp; sp = sp->next) {
+      grpc_fd_shutdown(exec_ctx, sp->emfd);
     }
     gpr_mu_unlock(&s->mu);
   } else {
@@ -298,7 +307,7 @@ error:
 
 /* event manager callback when reads are ready */
 static void on_read(grpc_exec_ctx *exec_ctx, void *arg, int success) {
-  server_port *sp = arg;
+  grpc_tcp_listener *sp = arg;
   grpc_fd *fdobj;
   size_t i;
 
@@ -364,9 +373,10 @@ error:
   }
 }
 
-static int add_socket_to_server(grpc_tcp_server *s, int fd,
-                                const struct sockaddr *addr, size_t addr_len) {
-  server_port *sp;
+static grpc_tcp_listener *add_socket_to_server(grpc_tcp_server *s, int fd,
+                                               const struct sockaddr *addr,
+                                               size_t addr_len) {
+  grpc_tcp_listener *sp = NULL;
   int port;
   char *addr_str;
   char *name;
@@ -376,32 +386,34 @@ static int add_socket_to_server(grpc_tcp_server *s, int fd,
     grpc_sockaddr_to_string(&addr_str, (struct sockaddr *)&addr, 1);
     gpr_asprintf(&name, "tcp-server-listener:%s", addr_str);
     gpr_mu_lock(&s->mu);
+    s->nports++;
     GPR_ASSERT(!s->on_accept_cb && "must add ports before starting server");
-    /* append it to the list under a lock */
-    if (s->nports == s->port_capacity) {
-      s->port_capacity *= 2;
-      s->ports = gpr_realloc(s->ports, sizeof(server_port) * s->port_capacity);
-    }
-    sp = &s->ports[s->nports++];
+    sp = gpr_malloc(sizeof(grpc_tcp_listener));
+    sp->next = s->head;
+    s->head = sp;
     sp->server = s;
     sp->fd = fd;
     sp->emfd = grpc_fd_create(fd, name);
     memcpy(sp->addr.untyped, addr, addr_len);
     sp->addr_len = addr_len;
+    sp->port = port;
+    sp->is_sibling = 0;
+    sp->sibling = NULL;
+    gpr_ref_init(&sp->refs, 1);
     GPR_ASSERT(sp->emfd);
     gpr_mu_unlock(&s->mu);
     gpr_free(addr_str);
     gpr_free(name);
   }
 
-  return port;
+  return sp;
 }
 
-int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
-                             size_t addr_len) {
-  int allocated_port1 = -1;
-  int allocated_port2 = -1;
-  unsigned i;
+grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
+                                            const void *addr, size_t addr_len) {
+  int allocated_port = -1;
+  grpc_tcp_listener *sp;
+  grpc_tcp_listener *sp2 = NULL;
   int fd;
   grpc_dualstack_mode dsmode;
   struct sockaddr_in6 addr6_v4mapped;
@@ -420,9 +432,9 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
   /* Check if this is a wildcard port, and if so, try to keep the port the same
      as some previously created listener. */
   if (grpc_sockaddr_get_port(addr) == 0) {
-    for (i = 0; i < s->nports; i++) {
+    for (sp = s->head; sp; sp = sp->next) {
       sockname_len = sizeof(sockname_temp);
-      if (0 == getsockname(s->ports[i].fd, (struct sockaddr *)&sockname_temp,
+      if (0 == getsockname(sp->fd, (struct sockaddr *)&sockname_temp,
                            &sockname_len)) {
         port = grpc_sockaddr_get_port((struct sockaddr *)&sockname_temp);
         if (port > 0) {
@@ -436,6 +448,8 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     }
   }
 
+  sp = NULL;
+
   if (grpc_sockaddr_to_v4mapped(addr, &addr6_v4mapped)) {
     addr = (const struct sockaddr *)&addr6_v4mapped;
     addr_len = sizeof(addr6_v4mapped);
@@ -449,14 +463,16 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     addr = (struct sockaddr *)&wild6;
     addr_len = sizeof(wild6);
     fd = grpc_create_dualstack_socket(addr, SOCK_STREAM, 0, &dsmode);
-    allocated_port1 = add_socket_to_server(s, fd, addr, addr_len);
+    sp = add_socket_to_server(s, fd, addr, addr_len);
+    allocated_port = sp->port;
     if (fd >= 0 && dsmode == GRPC_DSMODE_DUALSTACK) {
       goto done;
     }
 
     /* If we didn't get a dualstack socket, also listen on 0.0.0.0. */
-    if (port == 0 && allocated_port1 > 0) {
-      grpc_sockaddr_set_port((struct sockaddr *)&wild4, allocated_port1);
+    if (port == 0 && allocated_port > 0) {
+      grpc_sockaddr_set_port((struct sockaddr *)&wild4, allocated_port);
+      sp2 = sp;
     }
     addr = (struct sockaddr *)&wild4;
     addr_len = sizeof(wild4);
@@ -471,22 +487,32 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     addr = (struct sockaddr *)&addr4_copy;
     addr_len = sizeof(addr4_copy);
   }
-  allocated_port2 = add_socket_to_server(s, fd, addr, addr_len);
+  sp = add_socket_to_server(s, fd, addr, addr_len);
+  sp->sibling = sp2;
+  if (sp2) sp2->is_sibling = 1;
 
 done:
   gpr_free(allocated_addr);
-  return allocated_port1 >= 0 ? allocated_port1 : allocated_port2;
+  return sp;
 }
 
 int grpc_tcp_server_get_fd(grpc_tcp_server *s, unsigned port_index) {
-  return (port_index < s->nports) ? s->ports[port_index].fd : -1;
+  grpc_tcp_listener *sp;
+  for (sp = s->head; sp && port_index != 0; sp = sp->next, port_index--)
+    ;
+  if (port_index == 0 && sp) {
+    return sp->fd;
+  } else {
+    return -1;
+  }
 }
 
 void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                            grpc_pollset **pollsets, size_t pollset_count,
                            grpc_tcp_server_cb on_accept_cb,
                            void *on_accept_cb_arg) {
-  size_t i, j;
+  size_t i;
+  grpc_tcp_listener *sp;
   GPR_ASSERT(on_accept_cb);
   gpr_mu_lock(&s->mu);
   GPR_ASSERT(!s->on_accept_cb);
@@ -495,17 +521,40 @@ void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
   s->on_accept_cb_arg = on_accept_cb_arg;
   s->pollsets = pollsets;
   s->pollset_count = pollset_count;
-  for (i = 0; i < s->nports; i++) {
-    for (j = 0; j < pollset_count; j++) {
-      grpc_pollset_add_fd(exec_ctx, pollsets[j], s->ports[i].emfd);
+  for (sp = s->head; sp; sp = sp->next) {
+    for (i = 0; i < pollset_count; i++) {
+      grpc_pollset_add_fd(exec_ctx, pollsets[i], sp->emfd);
     }
-    s->ports[i].read_closure.cb = on_read;
-    s->ports[i].read_closure.cb_arg = &s->ports[i];
-    grpc_fd_notify_on_read(exec_ctx, s->ports[i].emfd,
-                           &s->ports[i].read_closure);
+    sp->read_closure.cb = on_read;
+    sp->read_closure.cb_arg = sp;
+    grpc_fd_notify_on_read(exec_ctx, sp->emfd, &sp->read_closure);
     s->active_ports++;
   }
   gpr_mu_unlock(&s->mu);
 }
 
+int grpc_tcp_listener_get_port(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  return sp->port;
+}
+
+void grpc_tcp_listener_ref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  gpr_ref(&sp->refs);
+}
+
+void grpc_tcp_listener_unref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  if (sp->is_sibling) return;
+  if (gpr_unref(&sp->refs)) {
+    grpc_tcp_listener *sibling = sp->sibling;
+    while (sibling) {
+      sp = sibling;
+      sibling = sp->sibling;
+      gpr_free(sp);
+    }
+    gpr_free(listener);
+  }
+}
+
 #endif

src/core/iomgr/tcp_server_windows.c

@@ -35,7 +35,8 @@
 
 #ifdef GPR_WINSOCK_SOCKET
 
-#define _GNU_SOURCE
+#include <io.h>
+
 #include "src/core/iomgr/sockaddr_utils.h"
 
 #include <grpc/support/alloc.h>
@@ -51,25 +52,29 @@
 #include "src/core/iomgr/tcp_server.h"
 #include "src/core/iomgr/tcp_windows.h"
 
-#define INIT_PORT_CAP 2
 #define MIN_SAFE_ACCEPT_QUEUE_SIZE 100
 
 /* one listening port */
-typedef struct server_port {
+struct grpc_tcp_listener {
   /* This seemingly magic number comes from AcceptEx's documentation. each
      address buffer needs to have at least 16 more bytes at their end. */
   gpr_uint8 addresses[(sizeof(struct sockaddr_in6) + 16) * 2];
   /* This will hold the socket for the next accept. */
   SOCKET new_socket;
-  /* The listener winsocked. */
+  /* The listener winsocket. */
   grpc_winsocket *socket;
+  /* The actual TCP port number. */
+  int port;
   grpc_tcp_server *server;
   /* The cached AcceptEx for that port. */
   LPFN_ACCEPTEX AcceptEx;
   int shutting_down;
   /* closure for socket notification of accept being ready */
   grpc_closure on_accept;
-} server_port;
+  gpr_refcount refs;
+  /* linked list */
+  struct grpc_tcp_listener *next;
+};
 
 /* the overall server */
 struct grpc_tcp_server {
@@ -82,10 +87,8 @@ struct grpc_tcp_server {
   /* active port count: how many ports are actually still listening */
   int active_ports;
 
-  /* all listening ports */
-  server_port *ports;
-  size_t nports;
-  size_t port_capacity;
+  /* linked list of server ports */
+  grpc_tcp_listener *head;
 
   /* shutdown callback */
   grpc_closure *shutdown_complete;
@@ -99,9 +102,7 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
   s->active_ports = 0;
   s->on_accept_cb = NULL;
   s->on_accept_cb_arg = NULL;
-  s->ports = gpr_malloc(sizeof(server_port) * INIT_PORT_CAP);
-  s->nports = 0;
-  s->port_capacity = INIT_PORT_CAP;
+  s->head = NULL;
   s->shutdown_complete = NULL;
   return s;
 }
@@ -109,26 +110,26 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
 static void dont_care_about_shutdown_completion(void *arg) {}
 
 static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
-  size_t i;
-
   grpc_exec_ctx_enqueue(exec_ctx, s->shutdown_complete, 1);
 
   /* Now that the accepts have been aborted, we can destroy the sockets.
      The IOCP won't get notified on these, so we can flag them as already
      closed by the system. */
-  for (i = 0; i < s->nports; i++) {
-    server_port *sp = &s->ports[i];
+  while (s->head) {
+    grpc_tcp_listener *sp = s->head;
+    s->head = sp->next;
+    sp->next = NULL;
     grpc_winsocket_destroy(sp->socket);
+    grpc_tcp_listener_unref(sp);
   }
-  gpr_free(s->ports);
   gpr_free(s);
 }
 
 /* Public function. Stops and destroys a grpc_tcp_server. */
 void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                              grpc_closure *shutdown_complete) {
-  size_t i;
   int immediately_done = 0;
+  grpc_tcp_listener *sp;
   gpr_mu_lock(&s->mu);
 
   s->shutdown_complete = shutdown_complete;
@@ -138,8 +139,7 @@ void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
   if (s->active_ports == 0) {
     immediately_done = 1;
   }
-  for (i = 0; i < s->nports; i++) {
-    server_port *sp = &s->ports[i];
+  for (sp = s->head; sp; sp = sp->next) {
     sp->shutting_down = 1;
     grpc_winsocket_shutdown(sp->socket);
   }
@@ -199,7 +199,7 @@ error:
 }
 
 static void decrement_active_ports_and_notify(grpc_exec_ctx *exec_ctx,
-                                              server_port *sp) {
+                                              grpc_tcp_listener *sp) {
   int notify = 0;
   sp->shutting_down = 0;
   gpr_mu_lock(&sp->server->mu);
@@ -216,7 +216,7 @@ static void decrement_active_ports_and_notify(grpc_exec_ctx *exec_ctx,
 
 /* In order to do an async accept, we need to create a socket first which
    will be the one assigned to the new incoming connection. */
-static void start_accept(grpc_exec_ctx *exec_ctx, server_port *port) {
+static void start_accept(grpc_exec_ctx *exec_ctx, grpc_tcp_listener *port) {
   SOCKET sock = INVALID_SOCKET;
   char *message;
   char *utf8_message;
@@ -276,7 +276,7 @@ failure:
 
 /* Event manager callback when reads are ready. */
 static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, int from_iocp) {
-  server_port *sp = arg;
+  grpc_tcp_listener *sp = arg;
   SOCKET sock = sp->new_socket;
   grpc_winsocket_callback_info *info = &sp->socket->read_info;
   grpc_endpoint *ep = NULL;
@@ -351,16 +351,17 @@ static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, int from_iocp) {
   start_accept(exec_ctx, sp);
 }
 
-static int add_socket_to_server(grpc_tcp_server *s, SOCKET sock,
-                                const struct sockaddr *addr, size_t addr_len) {
-  server_port *sp;
+static grpc_tcp_listener *add_socket_to_server(grpc_tcp_server *s, SOCKET sock,
+                                               const struct sockaddr *addr,
+                                               size_t addr_len) {
+  grpc_tcp_listener *sp = NULL;
   int port;
   int status;
   GUID guid = WSAID_ACCEPTEX;
   DWORD ioctl_num_bytes;
   LPFN_ACCEPTEX AcceptEx;
 
-  if (sock == INVALID_SOCKET) return -1;
+  if (sock == INVALID_SOCKET) return NULL;
 
   /* We need to grab the AcceptEx pointer for that port, as it may be
      interface-dependent. We'll cache it to avoid doing that again. */
@@ -373,37 +374,34 @@ static int add_socket_to_server(grpc_tcp_server *s, SOCKET sock,
     gpr_log(GPR_ERROR, "on_connect error: %s", utf8_message);
     gpr_free(utf8_message);
     closesocket(sock);
-    return -1;
+    return NULL;
   }
 
   port = prepare_socket(sock, addr, addr_len);
   if (port >= 0) {
     gpr_mu_lock(&s->mu);
     GPR_ASSERT(!s->on_accept_cb && "must add ports before starting server");
-    /* append it to the list under a lock */
-    if (s->nports == s->port_capacity) {
-      /* too many ports, and we need to store their address in a closure */
-      /* TODO(ctiller): make server_port a linked list */
-      abort();
-    }
-    sp = &s->ports[s->nports++];
+    sp = gpr_malloc(sizeof(grpc_tcp_listener));
+    sp->next = s->head;
+    s->head = sp;
     sp->server = s;
     sp->socket = grpc_winsocket_create(sock, "listener");
     sp->shutting_down = 0;
     sp->AcceptEx = AcceptEx;
     sp->new_socket = INVALID_SOCKET;
+    sp->port = port;
+    gpr_ref_init(&sp->refs, 1);
     grpc_closure_init(&sp->on_accept, on_accept, sp);
     GPR_ASSERT(sp->socket);
     gpr_mu_unlock(&s->mu);
   }
 
-  return port;
+  return sp;
 }
 
-int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
-                             size_t addr_len) {
-  int allocated_port = -1;
-  unsigned i;
+grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
+                                            const void *addr, size_t addr_len) {
+  grpc_tcp_listener *sp;
   SOCKET sock;
   struct sockaddr_in6 addr6_v4mapped;
   struct sockaddr_in6 wildcard;
@@ -415,9 +413,9 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
   /* Check if this is a wildcard port, and if so, try to keep the port the same
      as some previously created listener. */
   if (grpc_sockaddr_get_port(addr) == 0) {
-    for (i = 0; i < s->nports; i++) {
+    for (sp = s->head; sp; sp = sp->next) {
       sockname_len = sizeof(sockname_temp);
-      if (0 == getsockname(s->ports[i].socket->socket,
+      if (0 == getsockname(sp->socket->socket,
                            (struct sockaddr *)&sockname_temp, &sockname_len)) {
         port = grpc_sockaddr_get_port((struct sockaddr *)&sockname_temp);
         if (port > 0) {
@@ -452,33 +450,56 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     gpr_free(utf8_message);
   }
 
-  allocated_port = add_socket_to_server(s, sock, addr, addr_len);
+  sp = add_socket_to_server(s, sock, addr, addr_len);
   gpr_free(allocated_addr);
 
-  return allocated_port;
+  return sp;
 }
 
-SOCKET
-grpc_tcp_server_get_socket(grpc_tcp_server *s, unsigned index) {
-  return (index < s->nports) ? s->ports[index].socket->socket : INVALID_SOCKET;
+int grpc_tcp_server_get_fd(grpc_tcp_server *s, unsigned port_index) {
+  grpc_tcp_listener *sp;
+  for (sp = s->head; sp && port_index != 0; sp = sp->next, port_index--)
+    ;
+  if (port_index == 0 && sp) {
+    return _open_osfhandle(sp->socket->socket, 0);
+  } else {
+    return -1;
+  }
 }
 
 void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                            grpc_pollset **pollset, size_t pollset_count,
                            grpc_tcp_server_cb on_accept_cb,
                            void *on_accept_cb_arg) {
-  size_t i;
+  grpc_tcp_listener *sp;
   GPR_ASSERT(on_accept_cb);
   gpr_mu_lock(&s->mu);
   GPR_ASSERT(!s->on_accept_cb);
   GPR_ASSERT(s->active_ports == 0);
   s->on_accept_cb = on_accept_cb;
   s->on_accept_cb_arg = on_accept_cb_arg;
-  for (i = 0; i < s->nports; i++) {
-    start_accept(exec_ctx, s->ports + i);
+  for (sp = s->head; sp; sp = sp->next) {
+    start_accept(exec_ctx, sp);
     s->active_ports++;
   }
   gpr_mu_unlock(&s->mu);
 }
 
+int grpc_tcp_listener_get_port(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  return sp->port;
+}
+
+void grpc_tcp_listener_ref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  gpr_ref(&sp->refs);
+}
+
+void grpc_tcp_listener_unref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  if (gpr_unref(&sp->refs)) {
+    gpr_free(listener);
+  }
+}
+
 #endif /* GPR_WINSOCK_SOCKET */

src/core/iomgr/udp_server.c

@@ -179,7 +179,7 @@ static void deactivated_all_ports(grpc_exec_ctx *exec_ctx, grpc_udp_server *s) {
       }
       sp->destroyed_closure.cb = destroyed_port;
       sp->destroyed_closure.cb_arg = s;
-      grpc_fd_orphan(exec_ctx, sp->emfd, &sp->destroyed_closure,
+      grpc_fd_orphan(exec_ctx, sp->emfd, &sp->destroyed_closure, NULL,
                      "udp_listener_shutdown");
     }
     gpr_mu_unlock(&s->mu);

src/core/iomgr/workqueue_posix.c

@@ -115,7 +115,7 @@ static void on_readable(grpc_exec_ctx *exec_ctx, void *arg, int success) {
     /* HACK: let wakeup_fd code know that we stole the fd */
     workqueue->wakeup_fd.read_fd = 0;
     grpc_wakeup_fd_destroy(&workqueue->wakeup_fd);
-    grpc_fd_orphan(exec_ctx, workqueue->wakeup_read_fd, NULL, "destroy");
+    grpc_fd_orphan(exec_ctx, workqueue->wakeup_read_fd, NULL, NULL, "destroy");
     gpr_free(workqueue);
   } else {
     gpr_mu_lock(&workqueue->mu);
@@ -129,8 +129,6 @@ static void on_readable(grpc_exec_ctx *exec_ctx, void *arg, int success) {
 
 void grpc_workqueue_push(grpc_workqueue *workqueue, grpc_closure *closure,
                          int success) {
-  closure->success = success;
-  closure->next = NULL;
   gpr_mu_lock(&workqueue->mu);
   if (grpc_closure_list_empty(workqueue->closure_list)) {
     grpc_wakeup_fd_wakeup(&workqueue->wakeup_fd);

src/core/profiling/basic_timers.c

@@ -50,60 +50,197 @@ typedef struct gpr_timer_entry {
   gpr_timespec tm;
   const char *tagstr;
   const char *file;
-  int line;
+  short line;
   char type;
   gpr_uint8 important;
+  int thd;
 } gpr_timer_entry;
 
-#define MAX_COUNT (1024 * 1024 / sizeof(gpr_timer_entry))
+#define MAX_COUNT 1000000
 
-static __thread gpr_timer_entry g_log[MAX_COUNT];
-static __thread int g_count;
+typedef struct gpr_timer_log {
+  size_t num_entries;
+  struct gpr_timer_log *next;
+  struct gpr_timer_log *prev;
+  gpr_timer_entry log[MAX_COUNT];
+} gpr_timer_log;
+
+typedef struct gpr_timer_log_list {
+  gpr_timer_log *head;
+  /* valid iff head!=NULL */
+  gpr_timer_log *tail;
+} gpr_timer_log_list;
+
+static __thread gpr_timer_log *g_thread_log;
 static gpr_once g_once_init = GPR_ONCE_INIT;
 static FILE *output_file;
+static const char *output_filename = "latency_trace.txt";
+static pthread_mutex_t g_mu;
+static pthread_cond_t g_cv;
+static gpr_timer_log_list g_in_progress_logs;
+static gpr_timer_log_list g_done_logs;
+static int g_shutdown;
+static gpr_thd_id g_writing_thread;
+static __thread int g_thread_id;
+static int g_next_thread_id;
 
-static void close_output() { fclose(output_file); }
+static int timer_log_push_back(gpr_timer_log_list *list, gpr_timer_log *log) {
+  if (list->head == NULL) {
+    list->head = list->tail = log;
+    log->next = log->prev = NULL;
+    return 1;
+  } else {
+    log->prev = list->tail;
+    log->next = NULL;
+    list->tail->next = log;
+    list->tail = log;
+    return 0;
+  }
+}
 
-static void init_output() {
-  output_file = fopen("latency_trace.txt", "w");
-  GPR_ASSERT(output_file);
-  atexit(close_output);
+static gpr_timer_log *timer_log_pop_front(gpr_timer_log_list *list) {
+  gpr_timer_log *out = list->head;
+  if (out != NULL) {
+    list->head = out->next;
+    if (list->head != NULL) {
+      list->head->prev = NULL;
+    } else {
+      list->tail = NULL;
+    }
+  }
+  return out;
 }
 
-static void log_report() {
-  int i;
-  gpr_once_init(&g_once_init, init_output);
-  for (i = 0; i < g_count; i++) {
-    gpr_timer_entry *entry = &(g_log[i]);
+static void timer_log_remove(gpr_timer_log_list *list, gpr_timer_log *log) {
+  if (log->prev == NULL) {
+    list->head = log->next;
+    if (list->head != NULL) {
+      list->head->prev = NULL;
+    }
+  } else {
+    log->prev->next = log->next;
+  }
+  if (log->next == NULL) {
+    list->tail = log->prev;
+    if (list->tail != NULL) {
+      list->tail->next = NULL;
+    }
+  } else {
+    log->next->prev = log->prev;
+  }
+}
+
+static void write_log(gpr_timer_log *log) {
+  size_t i;
+  if (output_file == NULL) {
+    output_file = fopen(output_filename, "w");
+  }
+  for (i = 0; i < log->num_entries; i++) {
+    gpr_timer_entry *entry = &(log->log[i]);
+    if (gpr_time_cmp(entry->tm, gpr_time_0(entry->tm.clock_type)) < 0) {
+      entry->tm = gpr_time_0(entry->tm.clock_type);
+    }
     fprintf(output_file,
-            "{\"t\": %ld.%09d, \"thd\": \"%p\", \"type\": \"%c\", \"tag\": "
+            "{\"t\": %ld.%09d, \"thd\": \"%d\", \"type\": \"%c\", \"tag\": "
             "\"%s\", \"file\": \"%s\", \"line\": %d, \"imp\": %d}\n",
-            entry->tm.tv_sec, entry->tm.tv_nsec,
-            (void *)(gpr_intptr)gpr_thd_currentid(), entry->type, entry->tagstr,
-            entry->file, entry->line, entry->important);
+            entry->tm.tv_sec, entry->tm.tv_nsec, entry->thd, entry->type,
+            entry->tagstr, entry->file, entry->line, entry->important);
+  }
+}
+
+static void writing_thread(void *unused) {
+  gpr_timer_log *log;
+  pthread_mutex_lock(&g_mu);
+  for (;;) {
+    while ((log = timer_log_pop_front(&g_done_logs)) == NULL && !g_shutdown) {
+      pthread_cond_wait(&g_cv, &g_mu);
+    }
+    if (log != NULL) {
+      pthread_mutex_unlock(&g_mu);
+      write_log(log);
+      free(log);
+      pthread_mutex_lock(&g_mu);
+    }
+    if (g_shutdown) {
+      pthread_mutex_unlock(&g_mu);
+      return;
+    }
   }
+}
 
-  /* Now clear out the log */
-  g_count = 0;
+static void flush_logs(gpr_timer_log_list *list) {
+  gpr_timer_log *log;
+  while ((log = timer_log_pop_front(list)) != NULL) {
+    write_log(log);
+    free(log);
+  }
+}
+
+static void finish_writing() {
+  pthread_mutex_lock(&g_mu);
+  g_shutdown = 1;
+  pthread_cond_signal(&g_cv);
+  pthread_mutex_unlock(&g_mu);
+  gpr_thd_join(g_writing_thread);
+
+  gpr_log(GPR_INFO, "flushing logs");
+
+  pthread_mutex_lock(&g_mu);
+  flush_logs(&g_done_logs);
+  flush_logs(&g_in_progress_logs);
+  pthread_mutex_unlock(&g_mu);
+
+  if (output_file) {
+    fclose(output_file);
+  }
+}
+
+void gpr_timers_set_log_filename(const char *filename) {
+  output_filename = filename;
+}
+
+static void init_output() {
+  gpr_thd_options options = gpr_thd_options_default();
+  gpr_thd_options_set_joinable(&options);
+  gpr_thd_new(&g_writing_thread, writing_thread, NULL, &options);
+  atexit(finish_writing);
+}
+
+static void rotate_log() {
+  gpr_timer_log *new = malloc(sizeof(*new));
+  gpr_once_init(&g_once_init, init_output);
+  new->num_entries = 0;
+  pthread_mutex_lock(&g_mu);
+  if (g_thread_log != NULL) {
+    timer_log_remove(&g_in_progress_logs, g_thread_log);
+    if (timer_log_push_back(&g_done_logs, g_thread_log)) {
+      pthread_cond_signal(&g_cv);
+    }
+  } else {
+    g_thread_id = g_next_thread_id++;
+  }
+  timer_log_push_back(&g_in_progress_logs, new);
+  pthread_mutex_unlock(&g_mu);
+  g_thread_log = new;
 }
 
 static void gpr_timers_log_add(const char *tagstr, marker_type type,
                                int important, const char *file, int line) {
   gpr_timer_entry *entry;
 
-  /* TODO (vpai) : Improve concurrency */
-  if (g_count == MAX_COUNT) {
-    log_report();
+  if (g_thread_log == NULL || g_thread_log->num_entries == MAX_COUNT) {
+    rotate_log();
   }
 
-  entry = &g_log[g_count++];
+  entry = &g_thread_log->log[g_thread_log->num_entries++];
 
   entry->tm = gpr_now(GPR_CLOCK_PRECISE);
   entry->tagstr = tagstr;
   entry->type = type;
   entry->file = file;
-  entry->line = line;
+  entry->line = (short)line;
   entry->important = important != 0;
+  entry->thd = g_thread_id;
 }
 
 /* Latency profiler API implementation. */
@@ -131,4 +268,6 @@ void gpr_timers_global_destroy(void) {}
 void gpr_timers_global_init(void) {}
 
 void gpr_timers_global_destroy(void) {}
+
+void gpr_timers_set_log_filename(const char *filename) {}
 #endif /* GRPC_BASIC_PROFILER */

src/core/profiling/timers.h

@@ -48,6 +48,8 @@ void gpr_timer_begin(const char *tagstr, int important, const char *file,
 void gpr_timer_end(const char *tagstr, int important, const char *file,
                    int line);
 
+void gpr_timers_set_log_filename(const char *filename);
+
 #if !(defined(GRPC_STAP_PROFILER) + defined(GRPC_BASIC_PROFILER))
 /* No profiling. No-op all the things. */
 #define GPR_TIMER_MARK(tag, important) \

src/core/security/client_auth_filter.c

@@ -45,12 +45,13 @@
 #include "src/core/security/security_connector.h"
 #include "src/core/security/credentials.h"
 #include "src/core/surface/call.h"
+#include "src/core/transport/static_metadata.h"
 
 #define MAX_CREDENTIALS_METADATA_COUNT 4
 
 /* We can have a per-call credentials. */
 typedef struct {
-  grpc_credentials *creds;
+  grpc_call_credentials *creds;
   grpc_mdstr *host;
   grpc_mdstr *method;
   /* pollset bound to this call; if we need to make external
@@ -59,28 +60,30 @@ typedef struct {
      progress */
   grpc_pollset *pollset;
   grpc_transport_stream_op op;
-  size_t op_md_idx;
-  int sent_initial_metadata;
   gpr_uint8 security_context_set;
   grpc_linked_mdelem md_links[MAX_CREDENTIALS_METADATA_COUNT];
-  char *service_url;
+  grpc_auth_metadata_context auth_md_context;
 } call_data;
 
 /* We can have a per-channel credentials. */
 typedef struct {
   grpc_channel_security_connector *security_connector;
-  grpc_mdctx *md_ctx;
-  grpc_mdstr *authority_string;
-  grpc_mdstr *path_string;
-  grpc_mdstr *error_msg_key;
-  grpc_mdstr *status_key;
 } channel_data;
 
-static void reset_service_url(call_data *calld) {
-  if (calld->service_url != NULL) {
-    gpr_free(calld->service_url);
-    calld->service_url = NULL;
+static void reset_auth_metadata_context(
+    grpc_auth_metadata_context *auth_md_context) {
+  if (auth_md_context->service_url != NULL) {
+    gpr_free((char *)auth_md_context->service_url);
+    auth_md_context->service_url = NULL;
   }
+  if (auth_md_context->method_name != NULL) {
+    gpr_free((char *)auth_md_context->method_name);
+    auth_md_context->method_name = NULL;
+  }
+  GRPC_AUTH_CONTEXT_UNREF(
+      (grpc_auth_context *)auth_md_context->channel_auth_context,
+      "grpc_auth_metadata_context");
+  auth_md_context->channel_auth_context = NULL;
 }
 
 static void bubble_up_error(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
@@ -97,32 +100,34 @@ static void on_credentials_metadata(grpc_exec_ctx *exec_ctx, void *user_data,
                                     grpc_credentials_status status) {
   grpc_call_element *elem = (grpc_call_element *)user_data;
   call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
   grpc_transport_stream_op *op = &calld->op;
   grpc_metadata_batch *mdb;
   size_t i;
-  reset_service_url(calld);
+  reset_auth_metadata_context(&calld->auth_md_context);
   if (status != GRPC_CREDENTIALS_OK) {
     bubble_up_error(exec_ctx, elem, GRPC_STATUS_UNAUTHENTICATED,
                     "Credentials failed to get metadata.");
     return;
   }
   GPR_ASSERT(num_md <= MAX_CREDENTIALS_METADATA_COUNT);
-  GPR_ASSERT(op->send_ops && op->send_ops->nops > calld->op_md_idx &&
-             op->send_ops->ops[calld->op_md_idx].type == GRPC_OP_METADATA);
-  mdb = &op->send_ops->ops[calld->op_md_idx].data.metadata;
+  GPR_ASSERT(op->send_initial_metadata != NULL);
+  mdb = op->send_initial_metadata;
   for (i = 0; i < num_md; i++) {
     grpc_metadata_batch_add_tail(
         mdb, &calld->md_links[i],
-        grpc_mdelem_from_slices(chand->md_ctx, gpr_slice_ref(md_elems[i].key),
+        grpc_mdelem_from_slices(gpr_slice_ref(md_elems[i].key),
                                 gpr_slice_ref(md_elems[i].value)));
   }
   grpc_call_next_op(exec_ctx, elem, op);
 }
 
-void build_service_url(const char *url_scheme, call_data *calld) {
+void build_auth_metadata_context(grpc_security_connector *sc,
+                                 call_data *calld) {
   char *service = gpr_strdup(grpc_mdstr_as_c_string(calld->method));
   char *last_slash = strrchr(service, '/');
+  char *method_name = NULL;
+  char *service_url = NULL;
+  reset_auth_metadata_context(&calld->auth_md_context);
   if (last_slash == NULL) {
     gpr_log(GPR_ERROR, "No '/' found in fully qualified method name");
     service[0] = '\0';
@@ -131,11 +136,16 @@ void build_service_url(const char *url_scheme, call_data *calld) {
     service[1] = '\0';
   } else {
     *last_slash = '\0';
+    method_name = gpr_strdup(last_slash + 1);
   }
-  if (url_scheme == NULL) url_scheme = "";
-  reset_service_url(calld);
-  gpr_asprintf(&calld->service_url, "%s://%s%s", url_scheme,
+  if (method_name == NULL) method_name = gpr_strdup("");
+  gpr_asprintf(&service_url, "%s://%s%s",
+               sc->url_scheme == NULL ? "" : sc->url_scheme,
                grpc_mdstr_as_c_string(calld->host), service);
+  calld->auth_md_context.service_url = service_url;
+  calld->auth_md_context.method_name = method_name;
+  calld->auth_md_context.channel_auth_context =
+      GRPC_AUTH_CONTEXT_REF(sc->auth_context, "grpc_auth_metadata_context");
   gpr_free(service);
 }
 
@@ -146,39 +156,35 @@ static void send_security_metadata(grpc_exec_ctx *exec_ctx,
   channel_data *chand = elem->channel_data;
   grpc_client_security_context *ctx =
       (grpc_client_security_context *)op->context[GRPC_CONTEXT_SECURITY].value;
-  grpc_credentials *channel_creds =
+  grpc_call_credentials *channel_call_creds =
       chand->security_connector->request_metadata_creds;
-  int channel_creds_has_md =
-      (channel_creds != NULL) &&
-      grpc_credentials_has_request_metadata(channel_creds);
-  int call_creds_has_md = (ctx != NULL) && (ctx->creds != NULL) &&
-                          grpc_credentials_has_request_metadata(ctx->creds);
+  int call_creds_has_md = (ctx != NULL) && (ctx->creds != NULL);
 
-  if (!channel_creds_has_md && !call_creds_has_md) {
+  if (channel_call_creds == NULL && !call_creds_has_md) {
     /* Skip sending metadata altogether. */
     grpc_call_next_op(exec_ctx, elem, op);
     return;
   }
 
-  if (channel_creds_has_md && call_creds_has_md) {
-    calld->creds =
-        grpc_composite_credentials_create(channel_creds, ctx->creds, NULL);
+  if (channel_call_creds != NULL && call_creds_has_md) {
+    calld->creds = grpc_composite_call_credentials_create(channel_call_creds,
+                                                          ctx->creds, NULL);
     if (calld->creds == NULL) {
       bubble_up_error(exec_ctx, elem, GRPC_STATUS_INVALID_ARGUMENT,
                       "Incompatible credentials set on channel and call.");
       return;
     }
   } else {
-    calld->creds =
-        grpc_credentials_ref(call_creds_has_md ? ctx->creds : channel_creds);
+    calld->creds = grpc_call_credentials_ref(
+        call_creds_has_md ? ctx->creds : channel_call_creds);
   }
 
-  build_service_url(chand->security_connector->base.url_scheme, calld);
+  build_auth_metadata_context(&chand->security_connector->base, calld);
   calld->op = *op; /* Copy op (originates from the caller's stack). */
   GPR_ASSERT(calld->pollset);
-  grpc_credentials_get_request_metadata(exec_ctx, calld->creds, calld->pollset,
-                                        calld->service_url,
-                                        on_credentials_metadata, elem);
+  grpc_call_credentials_get_request_metadata(
+      exec_ctx, calld->creds, calld->pollset, calld->auth_md_context,
+      on_credentials_metadata, elem);
 }
 
 static void on_host_checked(grpc_exec_ctx *exec_ctx, void *user_data,
@@ -209,7 +215,6 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   grpc_linked_mdelem *l;
-  size_t i;
   grpc_client_security_context *sec_ctx = NULL;
 
   if (calld->security_context_set == 0 &&
@@ -228,53 +233,41 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
         chand->security_connector->base.auth_context, "client_auth_filter");
   }
 
-  if (op->bind_pollset != NULL) {
-    calld->pollset = op->bind_pollset;
-  }
-
-  if (op->send_ops != NULL && !calld->sent_initial_metadata) {
-    size_t nops = op->send_ops->nops;
-    grpc_stream_op *ops = op->send_ops->ops;
-    for (i = 0; i < nops; i++) {
-      grpc_stream_op *sop = &ops[i];
-      if (sop->type != GRPC_OP_METADATA) continue;
-      calld->op_md_idx = i;
-      calld->sent_initial_metadata = 1;
-      for (l = sop->data.metadata.list.head; l != NULL; l = l->next) {
-        grpc_mdelem *md = l->md;
-        /* Pointer comparison is OK for md_elems created from the same context.
-         */
-        if (md->key == chand->authority_string) {
-          if (calld->host != NULL) GRPC_MDSTR_UNREF(calld->host);
-          calld->host = GRPC_MDSTR_REF(md->value);
-        } else if (md->key == chand->path_string) {
-          if (calld->method != NULL) GRPC_MDSTR_UNREF(calld->method);
-          calld->method = GRPC_MDSTR_REF(md->value);
-        }
+  if (op->send_initial_metadata != NULL) {
+    for (l = op->send_initial_metadata->list.head; l != NULL; l = l->next) {
+      grpc_mdelem *md = l->md;
+      /* Pointer comparison is OK for md_elems created from the same context.
+       */
+      if (md->key == GRPC_MDSTR_AUTHORITY) {
+        if (calld->host != NULL) GRPC_MDSTR_UNREF(calld->host);
+        calld->host = GRPC_MDSTR_REF(md->value);
+      } else if (md->key == GRPC_MDSTR_PATH) {
+        if (calld->method != NULL) GRPC_MDSTR_UNREF(calld->method);
+        calld->method = GRPC_MDSTR_REF(md->value);
       }
-      if (calld->host != NULL) {
-        grpc_security_status status;
-        const char *call_host = grpc_mdstr_as_c_string(calld->host);
-        calld->op = *op; /* Copy op (originates from the caller's stack). */
-        status = grpc_channel_security_connector_check_call_host(
-            exec_ctx, chand->security_connector, call_host, on_host_checked,
-            elem);
-        if (status != GRPC_SECURITY_OK) {
-          if (status == GRPC_SECURITY_ERROR) {
-            char *error_msg;
-            gpr_asprintf(&error_msg,
-                         "Invalid host %s set in :authority metadata.",
-                         call_host);
-            bubble_up_error(exec_ctx, elem, GRPC_STATUS_INVALID_ARGUMENT,
-                            error_msg);
-            gpr_free(error_msg);
-          }
-          return; /* early exit */
+    }
+    if (calld->host != NULL) {
+      grpc_security_status status;
+      const char *call_host = grpc_mdstr_as_c_string(calld->host);
+      calld->op = *op; /* Copy op (originates from the caller's stack). */
+      status = grpc_channel_security_connector_check_call_host(
+          exec_ctx, chand->security_connector, call_host, on_host_checked,
+          elem);
+      if (status != GRPC_SECURITY_OK) {
+        if (status == GRPC_SECURITY_ERROR) {
+          char *error_msg;
+          gpr_asprintf(&error_msg,
+                       "Invalid host %s set in :authority metadata.",
+                       call_host);
+          bubble_up_error(exec_ctx, elem, GRPC_STATUS_INVALID_ARGUMENT,
+                          error_msg);
+          gpr_free(error_msg);
         }
+        return; /* early exit */
       }
-      send_security_metadata(exec_ctx, elem, op);
-      return; /* early exit */
     }
+    send_security_metadata(exec_ctx, elem, op);
+    return; /* early exit */
   }
 
   /* pass control down the stack */
@@ -283,41 +276,44 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+                           grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   memset(calld, 0, sizeof(*calld));
-  GPR_ASSERT(!initial_op || !initial_op->send_ops);
+}
+
+static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                        grpc_pollset *pollset) {
+  call_data *calld = elem->call_data;
+  calld->pollset = pollset;
 }
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
                               grpc_call_element *elem) {
   call_data *calld = elem->call_data;
-  grpc_credentials_unref(calld->creds);
+  grpc_call_credentials_unref(calld->creds);
   if (calld->host != NULL) {
     GRPC_MDSTR_UNREF(calld->host);
   }
   if (calld->method != NULL) {
     GRPC_MDSTR_UNREF(calld->method);
   }
-  reset_service_url(calld);
+  reset_auth_metadata_context(&calld->auth_md_context);
 }
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args,
-                              grpc_mdctx *metadata_context, int is_first,
-                              int is_last) {
-  grpc_security_connector *sc = grpc_find_security_connector_in_args(args);
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
+  grpc_security_connector *sc =
+      grpc_find_security_connector_in_args(args->channel_args);
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
 
   /* The first and the last filters tend to be implemented differently to
      handle the case that there's no 'next' filter to call on the up or down
      path */
-  GPR_ASSERT(!is_last);
+  GPR_ASSERT(!args->is_last);
   GPR_ASSERT(sc != NULL);
 
   /* initialize members */
@@ -325,11 +321,6 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
   chand->security_connector =
       (grpc_channel_security_connector *)GRPC_SECURITY_CONNECTOR_REF(
           sc, "client_auth_filter");
-  chand->md_ctx = metadata_context;
-  chand->authority_string = grpc_mdstr_from_string(chand->md_ctx, ":authority");
-  chand->path_string = grpc_mdstr_from_string(chand->md_ctx, ":path");
-  chand->error_msg_key = grpc_mdstr_from_string(chand->md_ctx, "grpc-message");
-  chand->status_key = grpc_mdstr_from_string(chand->md_ctx, "grpc-status");
 }
 
 /* Destructor for channel data */
@@ -338,24 +329,13 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
   grpc_channel_security_connector *ctx = chand->security_connector;
-  if (ctx != NULL)
+  if (ctx != NULL) {
     GRPC_SECURITY_CONNECTOR_UNREF(&ctx->base, "client_auth_filter");
-  if (chand->authority_string != NULL) {
-    GRPC_MDSTR_UNREF(chand->authority_string);
-  }
-  if (chand->error_msg_key != NULL) {
-    GRPC_MDSTR_UNREF(chand->error_msg_key);
-  }
-  if (chand->status_key != NULL) {
-    GRPC_MDSTR_UNREF(chand->status_key);
-  }
-  if (chand->path_string != NULL) {
-    GRPC_MDSTR_UNREF(chand->path_string);
   }
 }
 
 const grpc_channel_filter grpc_client_auth_filter = {
     auth_start_transport_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem,          destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,       destroy_channel_elem, grpc_call_next_get_peer,
+    init_call_elem, set_pollset, destroy_call_elem, sizeof(channel_data),
+    init_channel_elem, destroy_channel_elem, grpc_call_next_get_peer,
     "client-auth"};

src/core/security/credentials.c

@@ -33,16 +33,16 @@
 
 #include "src/core/security/credentials.h"
 
-#include <string.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/http_client_filter.h"
-#include "src/core/json/json.h"
 #include "src/core/httpcli/httpcli.h"
 #include "src/core/iomgr/iomgr.h"
-#include "src/core/surface/api_trace.h"
+#include "src/core/json/json.h"
 #include "src/core/support/string.h"
+#include "src/core/surface/api_trace.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
@@ -54,18 +54,18 @@
 /* -- Common. -- */
 
 struct grpc_credentials_metadata_request {
-  grpc_credentials *creds;
+  grpc_call_credentials *creds;
   grpc_credentials_metadata_cb cb;
   void *user_data;
 };
 
 static grpc_credentials_metadata_request *
-grpc_credentials_metadata_request_create(grpc_credentials *creds,
+grpc_credentials_metadata_request_create(grpc_call_credentials *creds,
                                          grpc_credentials_metadata_cb cb,
                                          void *user_data) {
   grpc_credentials_metadata_request *r =
       gpr_malloc(sizeof(grpc_credentials_metadata_request));
-  r->creds = grpc_credentials_ref(creds);
+  r->creds = grpc_call_credentials_ref(creds);
   r->cb = cb;
   r->user_data = user_data;
   return r;
@@ -73,66 +73,74 @@ grpc_credentials_metadata_request_create(grpc_credentials *creds,
 
 static void grpc_credentials_metadata_request_destroy(
     grpc_credentials_metadata_request *r) {
-  grpc_credentials_unref(r->creds);
+  grpc_call_credentials_unref(r->creds);
   gpr_free(r);
 }
 
-grpc_credentials *grpc_credentials_ref(grpc_credentials *creds) {
+grpc_channel_credentials *grpc_channel_credentials_ref(
+    grpc_channel_credentials *creds) {
   if (creds == NULL) return NULL;
   gpr_ref(&creds->refcount);
   return creds;
 }
 
-void grpc_credentials_unref(grpc_credentials *creds) {
+void grpc_channel_credentials_unref(grpc_channel_credentials *creds) {
   if (creds == NULL) return;
   if (gpr_unref(&creds->refcount)) {
-    creds->vtable->destruct(creds);
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
     gpr_free(creds);
   }
 }
 
-void grpc_credentials_release(grpc_credentials *creds) {
-  GRPC_API_TRACE("grpc_credentials_release(creds=%p)", 1, (creds));
-  grpc_credentials_unref(creds);
+void grpc_channel_credentials_release(grpc_channel_credentials *creds) {
+  GRPC_API_TRACE("grpc_channel_credentials_release(creds=%p)", 1, (creds));
+  grpc_channel_credentials_unref(creds);
 }
 
-int grpc_credentials_has_request_metadata(grpc_credentials *creds) {
-  if (creds == NULL) return 0;
-  return creds->vtable->has_request_metadata(creds);
+grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds) {
+  if (creds == NULL) return NULL;
+  gpr_ref(&creds->refcount);
+  return creds;
+}
+
+void grpc_call_credentials_unref(grpc_call_credentials *creds) {
+  if (creds == NULL) return;
+  if (gpr_unref(&creds->refcount)) {
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    gpr_free(creds);
+  }
 }
 
-int grpc_credentials_has_request_metadata_only(grpc_credentials *creds) {
-  if (creds == NULL) return 0;
-  return creds->vtable->has_request_metadata_only(creds);
+void grpc_call_credentials_release(grpc_call_credentials *creds) {
+  GRPC_API_TRACE("grpc_call_credentials_release(creds=%p)", 1, (creds));
+  grpc_call_credentials_unref(creds);
 }
 
-void grpc_credentials_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
-  if (creds == NULL || !grpc_credentials_has_request_metadata(creds) ||
-      creds->vtable->get_request_metadata == NULL) {
+void grpc_call_credentials_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
+  if (creds == NULL || creds->vtable->get_request_metadata == NULL) {
     if (cb != NULL) {
       cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK);
     }
     return;
   }
-  creds->vtable->get_request_metadata(exec_ctx, creds, pollset, service_url, cb,
+  creds->vtable->get_request_metadata(exec_ctx, creds, pollset, context, cb,
                                       user_data);
 }
 
-grpc_security_status grpc_credentials_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+grpc_security_status grpc_channel_credentials_create_security_connector(
+    grpc_channel_credentials *channel_creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args) {
   *new_args = NULL;
-  if (creds == NULL || creds->vtable->create_security_connector == NULL ||
-      grpc_credentials_has_request_metadata_only(creds)) {
-    gpr_log(GPR_ERROR,
-            "Invalid credentials for creating a security connector.");
+  if (channel_creds == NULL) {
     return GRPC_SECURITY_ERROR;
   }
-  return creds->vtable->create_security_connector(
-      creds, target, args, request_metadata_creds, sc, new_args);
+  GPR_ASSERT(channel_creds->vtable->create_security_connector != NULL);
+  return channel_creds->vtable->create_security_connector(
+      channel_creds, NULL, target, args, sc, new_args);
 }
 
 grpc_server_credentials *grpc_server_credentials_ref(
@@ -145,7 +153,7 @@ grpc_server_credentials *grpc_server_credentials_ref(
 void grpc_server_credentials_unref(grpc_server_credentials *creds) {
   if (creds == NULL) return;
   if (gpr_unref(&creds->refcount)) {
-    creds->vtable->destruct(creds);
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
     if (creds->processor.destroy != NULL && creds->processor.state != NULL) {
       creds->processor.destroy(creds->processor.state);
     }
@@ -200,8 +208,7 @@ grpc_arg grpc_server_credentials_to_arg(grpc_server_credentials *p) {
   return arg;
 }
 
-grpc_server_credentials *grpc_server_credentials_from_arg(
-    const grpc_arg *arg) {
+grpc_server_credentials *grpc_server_credentials_from_arg(const grpc_arg *arg) {
   if (strcmp(arg->key, GRPC_SERVER_CREDENTIALS_ARG) != 0) return NULL;
   if (arg->type != GRPC_ARG_POINTER) {
     gpr_log(GPR_ERROR, "Invalid type %d for arg %s", arg->type,
@@ -225,7 +232,7 @@ grpc_server_credentials *grpc_find_server_credentials_in_args(
 
 /* -- Ssl credentials. -- */
 
-static void ssl_destruct(grpc_credentials *creds) {
+static void ssl_destruct(grpc_channel_credentials *creds) {
   grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
   if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
   if (c->config.pem_private_key != NULL) gpr_free(c->config.pem_private_key);
@@ -254,15 +261,9 @@ static void ssl_server_destruct(grpc_server_credentials *creds) {
   if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
 }
 
-static int ssl_has_request_metadata(const grpc_credentials *creds) { return 0; }
-
-static int ssl_has_request_metadata_only(const grpc_credentials *creds) {
-  return 0;
-}
-
 static grpc_security_status ssl_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
+    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
     grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
   grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
   grpc_security_status status = GRPC_SECURITY_OK;
@@ -279,7 +280,7 @@ static grpc_security_status ssl_create_security_connector(
     }
   }
   status = grpc_ssl_channel_security_connector_create(
-      request_metadata_creds, &c->config, target, overridden_target_name, sc);
+      call_creds, &c->config, target, overridden_target_name, sc);
   if (status != GRPC_SECURITY_OK) {
     return status;
   }
@@ -296,9 +297,8 @@ static grpc_security_status ssl_server_create_security_connector(
   return grpc_ssl_server_security_connector_create(&c->config, sc);
 }
 
-static grpc_credentials_vtable ssl_vtable = {
-    ssl_destruct, ssl_has_request_metadata, ssl_has_request_metadata_only, NULL,
-    ssl_create_security_connector};
+static grpc_channel_credentials_vtable ssl_vtable = {
+    ssl_destruct, ssl_create_security_connector};
 
 static grpc_server_credentials_vtable ssl_server_vtable = {
     ssl_server_destruct, ssl_server_create_security_connector};
@@ -363,7 +363,7 @@ static void ssl_build_server_config(
   }
 }
 
-grpc_credentials *grpc_ssl_credentials_create(
+grpc_channel_credentials *grpc_ssl_credentials_create(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pair,
     void *reserved) {
   grpc_ssl_credentials *c = gpr_malloc(sizeof(grpc_ssl_credentials));
@@ -374,7 +374,7 @@ grpc_credentials *grpc_ssl_credentials_create(
       3, (pem_root_certs, pem_key_cert_pair, reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(grpc_ssl_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_SSL;
+  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
   c->base.vtable = &ssl_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   ssl_build_config(pem_root_certs, pem_key_cert_pair, &c->config);
@@ -394,7 +394,7 @@ grpc_server_credentials *grpc_ssl_server_credentials_create(
           force_client_auth, reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(grpc_ssl_server_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_SSL;
+  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
   gpr_ref_init(&c->base.refcount, 1);
   c->base.vtable = &ssl_server_vtable;
   ssl_build_server_config(pem_root_certs, pem_key_cert_pairs,
@@ -416,7 +416,7 @@ static void jwt_reset_cache(grpc_service_account_jwt_access_credentials *c) {
   c->cached.jwt_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
 }
 
-static void jwt_destruct(grpc_credentials *creds) {
+static void jwt_destruct(grpc_call_credentials *creds) {
   grpc_service_account_jwt_access_credentials *c =
       (grpc_service_account_jwt_access_credentials *)creds;
   grpc_auth_json_key_destruct(&c->key);
@@ -424,15 +424,12 @@ static void jwt_destruct(grpc_credentials *creds) {
   gpr_mu_destroy(&c->cache_mu);
 }
 
-static int jwt_has_request_metadata(const grpc_credentials *creds) { return 1; }
-
-static int jwt_has_request_metadata_only(const grpc_credentials *creds) {
-  return 1;
-}
-
-static void jwt_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void jwt_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                     grpc_call_credentials *creds,
+                                     grpc_pollset *pollset,
+                                     grpc_auth_metadata_context context,
+                                     grpc_credentials_metadata_cb cb,
+                                     void *user_data) {
   grpc_service_account_jwt_access_credentials *c =
       (grpc_service_account_jwt_access_credentials *)creds;
   gpr_timespec refresh_threshold = gpr_time_from_seconds(
@@ -443,7 +440,7 @@ static void jwt_get_request_metadata(
   {
     gpr_mu_lock(&c->cache_mu);
     if (c->cached.service_url != NULL &&
-        strcmp(c->cached.service_url, service_url) == 0 &&
+        strcmp(c->cached.service_url, context.service_url) == 0 &&
         c->cached.jwt_md != NULL &&
         (gpr_time_cmp(gpr_time_sub(c->cached.jwt_expiration,
                                    gpr_now(GPR_CLOCK_REALTIME)),
@@ -458,14 +455,15 @@ static void jwt_get_request_metadata(
     /* Generate a new jwt. */
     gpr_mu_lock(&c->cache_mu);
     jwt_reset_cache(c);
-    jwt = grpc_jwt_encode_and_sign(&c->key, service_url, c->jwt_lifetime, NULL);
+    jwt = grpc_jwt_encode_and_sign(&c->key, context.service_url,
+                                   c->jwt_lifetime, NULL);
     if (jwt != NULL) {
       char *md_value;
       gpr_asprintf(&md_value, "Bearer %s", jwt);
       gpr_free(jwt);
       c->cached.jwt_expiration =
           gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), c->jwt_lifetime);
-      c->cached.service_url = gpr_strdup(service_url);
+      c->cached.service_url = gpr_strdup(context.service_url);
       c->cached.jwt_md = grpc_credentials_md_store_create(1);
       grpc_credentials_md_store_add_cstrings(
           c->cached.jwt_md, GRPC_AUTHORIZATION_METADATA_KEY, md_value);
@@ -484,11 +482,10 @@ static void jwt_get_request_metadata(
   }
 }
 
-static grpc_credentials_vtable jwt_vtable = {
-    jwt_destruct, jwt_has_request_metadata, jwt_has_request_metadata_only,
-    jwt_get_request_metadata, NULL};
+static grpc_call_credentials_vtable jwt_vtable = {jwt_destruct,
+                                                  jwt_get_request_metadata};
 
-grpc_credentials *
+grpc_call_credentials *
 grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
     grpc_auth_json_key key, gpr_timespec token_lifetime) {
   grpc_service_account_jwt_access_credentials *c;
@@ -498,7 +495,7 @@ grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
   }
   c = gpr_malloc(sizeof(grpc_service_account_jwt_access_credentials));
   memset(c, 0, sizeof(grpc_service_account_jwt_access_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_JWT;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_JWT;
   gpr_ref_init(&c->base.refcount, 1);
   c->base.vtable = &jwt_vtable;
   c->key = key;
@@ -508,7 +505,7 @@ grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
   return &c->base;
 }
 
-grpc_credentials *grpc_service_account_jwt_access_credentials_create(
+grpc_call_credentials *grpc_service_account_jwt_access_credentials_create(
     const char *json_key, gpr_timespec token_lifetime, void *reserved) {
   GRPC_API_TRACE(
       "grpc_service_account_jwt_access_credentials_create("
@@ -525,7 +522,7 @@ grpc_credentials *grpc_service_account_jwt_access_credentials_create(
 
 /* -- Oauth2TokenFetcher credentials -- */
 
-static void oauth2_token_fetcher_destruct(grpc_credentials *creds) {
+static void oauth2_token_fetcher_destruct(grpc_call_credentials *creds) {
   grpc_oauth2_token_fetcher_credentials *c =
       (grpc_oauth2_token_fetcher_credentials *)creds;
   grpc_credentials_md_store_unref(c->access_token_md);
@@ -533,16 +530,6 @@ static void oauth2_token_fetcher_destruct(grpc_credentials *creds) {
   grpc_httpcli_context_destroy(&c->httpcli_context);
 }
 
-static int oauth2_token_fetcher_has_request_metadata(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
-static int oauth2_token_fetcher_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
 grpc_credentials_status
 grpc_oauth2_token_fetcher_credentials_parse_server_response(
     const grpc_httpcli_response *response, grpc_credentials_md_store **token_md,
@@ -660,8 +647,9 @@ static void on_oauth2_token_fetcher_http_response(
 }
 
 static void oauth2_token_fetcher_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
   grpc_oauth2_token_fetcher_credentials *c =
       (grpc_oauth2_token_fetcher_credentials *)creds;
   gpr_timespec refresh_threshold = gpr_time_from_seconds(
@@ -694,7 +682,7 @@ static void oauth2_token_fetcher_get_request_metadata(
 static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
                                       grpc_fetch_oauth2_func fetch_func) {
   memset(c, 0, sizeof(grpc_oauth2_token_fetcher_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
   gpr_ref_init(&c->base.refcount, 1);
   gpr_mu_init(&c->mu);
   c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
@@ -704,10 +692,8 @@ static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
 
 /* -- GoogleComputeEngine credentials. -- */
 
-static grpc_credentials_vtable compute_engine_vtable = {
-    oauth2_token_fetcher_destruct, oauth2_token_fetcher_has_request_metadata,
-    oauth2_token_fetcher_has_request_metadata_only,
-    oauth2_token_fetcher_get_request_metadata, NULL};
+static grpc_call_credentials_vtable compute_engine_vtable = {
+    oauth2_token_fetcher_destruct, oauth2_token_fetcher_get_request_metadata};
 
 static void compute_engine_fetch_oauth2(
     grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
@@ -724,7 +710,7 @@ static void compute_engine_fetch_oauth2(
                    response_cb, metadata_req);
 }
 
-grpc_credentials *grpc_google_compute_engine_credentials_create(
+grpc_call_credentials *grpc_google_compute_engine_credentials_create(
     void *reserved) {
   grpc_oauth2_token_fetcher_credentials *c =
       gpr_malloc(sizeof(grpc_oauth2_token_fetcher_credentials));
@@ -738,17 +724,15 @@ grpc_credentials *grpc_google_compute_engine_credentials_create(
 
 /* -- GoogleRefreshToken credentials. -- */
 
-static void refresh_token_destruct(grpc_credentials *creds) {
+static void refresh_token_destruct(grpc_call_credentials *creds) {
   grpc_google_refresh_token_credentials *c =
       (grpc_google_refresh_token_credentials *)creds;
   grpc_auth_refresh_token_destruct(&c->refresh_token);
   oauth2_token_fetcher_destruct(&c->base.base);
 }
 
-static grpc_credentials_vtable refresh_token_vtable = {
-    refresh_token_destruct, oauth2_token_fetcher_has_request_metadata,
-    oauth2_token_fetcher_has_request_metadata_only,
-    oauth2_token_fetcher_get_request_metadata, NULL};
+static grpc_call_credentials_vtable refresh_token_vtable = {
+    refresh_token_destruct, oauth2_token_fetcher_get_request_metadata};
 
 static void refresh_token_fetch_oauth2(
     grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
@@ -774,7 +758,8 @@ static void refresh_token_fetch_oauth2(
   gpr_free(body);
 }
 
-grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
+grpc_call_credentials *
+grpc_refresh_token_credentials_create_from_auth_refresh_token(
     grpc_auth_refresh_token refresh_token) {
   grpc_google_refresh_token_credentials *c;
   if (!grpc_auth_refresh_token_is_valid(&refresh_token)) {
@@ -789,7 +774,7 @@ grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
   return &c->base.base;
 }
 
-grpc_credentials *grpc_google_refresh_token_credentials_create(
+grpc_call_credentials *grpc_google_refresh_token_credentials_create(
     const char *json_refresh_token, void *reserved) {
   GRPC_API_TRACE(
       "grpc_refresh_token_credentials_create(json_refresh_token=%s, "
@@ -802,20 +787,11 @@ grpc_credentials *grpc_google_refresh_token_credentials_create(
 
 /* -- Metadata-only credentials. -- */
 
-static void md_only_test_destruct(grpc_credentials *creds) {
+static void md_only_test_destruct(grpc_call_credentials *creds) {
   grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
   grpc_credentials_md_store_unref(c->md_store);
 }
 
-static int md_only_test_has_request_metadata(const grpc_credentials *creds) {
-  return 1;
-}
-
-static int md_only_test_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
 static void on_simulated_token_fetch_done(void *user_data) {
   grpc_credentials_metadata_request *r =
       (grpc_credentials_metadata_request *)user_data;
@@ -828,8 +804,9 @@ static void on_simulated_token_fetch_done(void *user_data) {
 }
 
 static void md_only_test_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
   grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
 
   if (c->is_async) {
@@ -842,18 +819,15 @@ static void md_only_test_get_request_metadata(
   }
 }
 
-static grpc_credentials_vtable md_only_test_vtable = {
-    md_only_test_destruct, md_only_test_has_request_metadata,
-    md_only_test_has_request_metadata_only, md_only_test_get_request_metadata,
-    NULL};
+static grpc_call_credentials_vtable md_only_test_vtable = {
+    md_only_test_destruct, md_only_test_get_request_metadata};
 
-grpc_credentials *grpc_md_only_test_credentials_create(const char *md_key,
-                                                       const char *md_value,
-                                                       int is_async) {
+grpc_call_credentials *grpc_md_only_test_credentials_create(
+    const char *md_key, const char *md_value, int is_async) {
   grpc_md_only_test_credentials *c =
       gpr_malloc(sizeof(grpc_md_only_test_credentials));
   memset(c, 0, sizeof(grpc_md_only_test_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
   c->base.vtable = &md_only_test_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->md_store = grpc_credentials_md_store_create(1);
@@ -864,34 +838,24 @@ grpc_credentials *grpc_md_only_test_credentials_create(const char *md_key,
 
 /* -- Oauth2 Access Token credentials. -- */
 
-static void access_token_destruct(grpc_credentials *creds) {
+static void access_token_destruct(grpc_call_credentials *creds) {
   grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
   grpc_credentials_md_store_unref(c->access_token_md);
 }
 
-static int access_token_has_request_metadata(const grpc_credentials *creds) {
-  return 1;
-}
-
-static int access_token_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
 static void access_token_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
   grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
   cb(exec_ctx, user_data, c->access_token_md->entries, 1, GRPC_CREDENTIALS_OK);
 }
 
-static grpc_credentials_vtable access_token_vtable = {
-    access_token_destruct, access_token_has_request_metadata,
-    access_token_has_request_metadata_only, access_token_get_request_metadata,
-    NULL};
+static grpc_call_credentials_vtable access_token_vtable = {
+    access_token_destruct, access_token_get_request_metadata};
 
-grpc_credentials *grpc_access_token_credentials_create(const char *access_token,
-                                                       void *reserved) {
+grpc_call_credentials *grpc_access_token_credentials_create(
+    const char *access_token, void *reserved) {
   grpc_access_token_credentials *c =
       gpr_malloc(sizeof(grpc_access_token_credentials));
   char *token_md_value;
@@ -901,7 +865,7 @@ grpc_credentials *grpc_access_token_credentials_create(const char *access_token,
       2, (access_token, reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(grpc_access_token_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
   c->base.vtable = &access_token_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->access_token_md = grpc_credentials_md_store_create(1);
@@ -914,31 +878,11 @@ grpc_credentials *grpc_access_token_credentials_create(const char *access_token,
 
 /* -- Fake transport security credentials. -- */
 
-static void fake_transport_security_credentials_destruct(
-    grpc_credentials *creds) {
-  /* Nothing to do here. */
-}
-
-static void fake_transport_security_server_credentials_destruct(
-    grpc_server_credentials *creds) {
-  /* Nothing to do here. */
-}
-
-static int fake_transport_security_has_request_metadata(
-    const grpc_credentials *creds) {
-  return 0;
-}
-
-static int fake_transport_security_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 0;
-}
-
 static grpc_security_status fake_transport_security_create_security_connector(
-    grpc_credentials *c, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
+    grpc_channel_credentials *c, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
     grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
-  *sc = grpc_fake_channel_security_connector_create(request_metadata_creds, 1);
+  *sc = grpc_fake_channel_security_connector_create(call_creds, 1);
   return GRPC_SECURITY_OK;
 }
 
@@ -949,21 +893,19 @@ fake_transport_security_server_create_security_connector(
   return GRPC_SECURITY_OK;
 }
 
-static grpc_credentials_vtable fake_transport_security_credentials_vtable = {
-    fake_transport_security_credentials_destruct,
-    fake_transport_security_has_request_metadata,
-    fake_transport_security_has_request_metadata_only, NULL,
-    fake_transport_security_create_security_connector};
+static grpc_channel_credentials_vtable
+    fake_transport_security_credentials_vtable = {
+        NULL, fake_transport_security_create_security_connector};
 
 static grpc_server_credentials_vtable
     fake_transport_security_server_credentials_vtable = {
-        fake_transport_security_server_credentials_destruct,
-        fake_transport_security_server_create_security_connector};
+        NULL, fake_transport_security_server_create_security_connector};
 
-grpc_credentials *grpc_fake_transport_security_credentials_create(void) {
-  grpc_credentials *c = gpr_malloc(sizeof(grpc_credentials));
-  memset(c, 0, sizeof(grpc_credentials));
-  c->type = GRPC_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
+grpc_channel_credentials *grpc_fake_transport_security_credentials_create(
+    void) {
+  grpc_channel_credentials *c = gpr_malloc(sizeof(grpc_channel_credentials));
+  memset(c, 0, sizeof(grpc_channel_credentials));
+  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
   c->vtable = &fake_transport_security_credentials_vtable;
   gpr_ref_init(&c->refcount, 1);
   return c;
@@ -973,69 +915,45 @@ grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
     void) {
   grpc_server_credentials *c = gpr_malloc(sizeof(grpc_server_credentials));
   memset(c, 0, sizeof(grpc_server_credentials));
-  c->type = GRPC_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
+  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
   gpr_ref_init(&c->refcount, 1);
   c->vtable = &fake_transport_security_server_credentials_vtable;
   return c;
 }
 
-/* -- Composite credentials. -- */
+/* -- Composite call credentials. -- */
 
 typedef struct {
-  grpc_composite_credentials *composite_creds;
+  grpc_composite_call_credentials *composite_creds;
   size_t creds_index;
   grpc_credentials_md_store *md_elems;
-  char *service_url;
+  grpc_auth_metadata_context auth_md_context;
   void *user_data;
   grpc_pollset *pollset;
   grpc_credentials_metadata_cb cb;
-} grpc_composite_credentials_metadata_context;
+} grpc_composite_call_credentials_metadata_context;
 
-static void composite_destruct(grpc_credentials *creds) {
-  grpc_composite_credentials *c = (grpc_composite_credentials *)creds;
+static void composite_call_destruct(grpc_call_credentials *creds) {
+  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
   size_t i;
   for (i = 0; i < c->inner.num_creds; i++) {
-    grpc_credentials_unref(c->inner.creds_array[i]);
+    grpc_call_credentials_unref(c->inner.creds_array[i]);
   }
   gpr_free(c->inner.creds_array);
 }
 
-static int composite_has_request_metadata(const grpc_credentials *creds) {
-  const grpc_composite_credentials *c =
-      (const grpc_composite_credentials *)creds;
-  size_t i;
-  for (i = 0; i < c->inner.num_creds; i++) {
-    if (grpc_credentials_has_request_metadata(c->inner.creds_array[i])) {
-      return 1;
-    }
-  }
-  return 0;
-}
-
-static int composite_has_request_metadata_only(const grpc_credentials *creds) {
-  const grpc_composite_credentials *c =
-      (const grpc_composite_credentials *)creds;
-  size_t i;
-  for (i = 0; i < c->inner.num_creds; i++) {
-    if (!grpc_credentials_has_request_metadata_only(c->inner.creds_array[i])) {
-      return 0;
-    }
-  }
-  return 1;
-}
-
-static void composite_md_context_destroy(
-    grpc_composite_credentials_metadata_context *ctx) {
+static void composite_call_md_context_destroy(
+    grpc_composite_call_credentials_metadata_context *ctx) {
   grpc_credentials_md_store_unref(ctx->md_elems);
-  if (ctx->service_url != NULL) gpr_free(ctx->service_url);
   gpr_free(ctx);
 }
 
-static void composite_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
-                                  grpc_credentials_md *md_elems, size_t num_md,
-                                  grpc_credentials_status status) {
-  grpc_composite_credentials_metadata_context *ctx =
-      (grpc_composite_credentials_metadata_context *)user_data;
+static void composite_call_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
+                                       grpc_credentials_md *md_elems,
+                                       size_t num_md,
+                                       grpc_credentials_status status) {
+  grpc_composite_call_credentials_metadata_context *ctx =
+      (grpc_composite_call_credentials_metadata_context *)user_data;
   if (status != GRPC_CREDENTIALS_OK) {
     ctx->cb(exec_ctx, ctx->user_data, NULL, 0, status);
     return;
@@ -1051,158 +969,112 @@ static void composite_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
   }
 
   /* See if we need to get some more metadata. */
-  while (ctx->creds_index < ctx->composite_creds->inner.num_creds) {
-    grpc_credentials *inner_creds =
+  if (ctx->creds_index < ctx->composite_creds->inner.num_creds) {
+    grpc_call_credentials *inner_creds =
         ctx->composite_creds->inner.creds_array[ctx->creds_index++];
-    if (grpc_credentials_has_request_metadata(inner_creds)) {
-      grpc_credentials_get_request_metadata(exec_ctx, inner_creds, ctx->pollset,
-                                            ctx->service_url,
-                                            composite_metadata_cb, ctx);
-      return;
-    }
+    grpc_call_credentials_get_request_metadata(
+        exec_ctx, inner_creds, ctx->pollset, ctx->auth_md_context,
+        composite_call_metadata_cb, ctx);
+    return;
   }
 
   /* We're done!. */
   ctx->cb(exec_ctx, ctx->user_data, ctx->md_elems->entries,
           ctx->md_elems->num_entries, GRPC_CREDENTIALS_OK);
-  composite_md_context_destroy(ctx);
+  composite_call_md_context_destroy(ctx);
 }
 
-static void composite_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
-  grpc_composite_credentials *c = (grpc_composite_credentials *)creds;
-  grpc_composite_credentials_metadata_context *ctx;
-  if (!grpc_credentials_has_request_metadata(creds)) {
-    cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK);
-    return;
-  }
-  ctx = gpr_malloc(sizeof(grpc_composite_credentials_metadata_context));
-  memset(ctx, 0, sizeof(grpc_composite_credentials_metadata_context));
-  ctx->service_url = gpr_strdup(service_url);
+static void composite_call_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context auth_md_context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
+  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
+  grpc_composite_call_credentials_metadata_context *ctx;
+
+  ctx = gpr_malloc(sizeof(grpc_composite_call_credentials_metadata_context));
+  memset(ctx, 0, sizeof(grpc_composite_call_credentials_metadata_context));
+  ctx->auth_md_context = auth_md_context;
   ctx->user_data = user_data;
   ctx->cb = cb;
   ctx->composite_creds = c;
   ctx->pollset = pollset;
   ctx->md_elems = grpc_credentials_md_store_create(c->inner.num_creds);
-  while (ctx->creds_index < c->inner.num_creds) {
-    grpc_credentials *inner_creds = c->inner.creds_array[ctx->creds_index++];
-    if (grpc_credentials_has_request_metadata(inner_creds)) {
-      grpc_credentials_get_request_metadata(exec_ctx, inner_creds, pollset,
-                                            service_url, composite_metadata_cb,
-                                            ctx);
-      return;
-    }
-  }
-  GPR_ASSERT(0); /* Should have exited before. */
+  grpc_call_credentials_get_request_metadata(
+      exec_ctx, c->inner.creds_array[ctx->creds_index++], pollset,
+      auth_md_context, composite_call_metadata_cb, ctx);
 }
 
-static grpc_security_status composite_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
-  grpc_composite_credentials *c = (grpc_composite_credentials *)creds;
-  if (c->connector_creds == NULL) {
-    gpr_log(GPR_ERROR,
-            "Cannot create security connector, missing connector credentials.");
-    return GRPC_SECURITY_ERROR;
-  }
-  return grpc_credentials_create_security_connector(c->connector_creds, target,
-                                                    args, creds, sc, new_args);
-}
-
-static grpc_credentials_vtable composite_credentials_vtable = {
-    composite_destruct, composite_has_request_metadata,
-    composite_has_request_metadata_only, composite_get_request_metadata,
-    composite_create_security_connector};
+static grpc_call_credentials_vtable composite_call_credentials_vtable = {
+    composite_call_destruct, composite_call_get_request_metadata};
 
-static grpc_credentials_array get_creds_array(grpc_credentials **creds_addr) {
-  grpc_credentials_array result;
-  grpc_credentials *creds = *creds_addr;
+static grpc_call_credentials_array get_creds_array(
+    grpc_call_credentials **creds_addr) {
+  grpc_call_credentials_array result;
+  grpc_call_credentials *creds = *creds_addr;
   result.creds_array = creds_addr;
   result.num_creds = 1;
-  if (strcmp(creds->type, GRPC_CREDENTIALS_TYPE_COMPOSITE) == 0) {
-    result = *grpc_composite_credentials_get_credentials(creds);
+  if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
+    result = *grpc_composite_call_credentials_get_credentials(creds);
   }
   return result;
 }
 
-grpc_credentials *grpc_composite_credentials_create(grpc_credentials *creds1,
-                                                    grpc_credentials *creds2,
-                                                    void *reserved) {
+grpc_call_credentials *grpc_composite_call_credentials_create(
+    grpc_call_credentials *creds1, grpc_call_credentials *creds2,
+    void *reserved) {
   size_t i;
   size_t creds_array_byte_size;
-  grpc_credentials_array creds1_array;
-  grpc_credentials_array creds2_array;
-  grpc_composite_credentials *c;
+  grpc_call_credentials_array creds1_array;
+  grpc_call_credentials_array creds2_array;
+  grpc_composite_call_credentials *c;
   GRPC_API_TRACE(
-      "grpc_composite_credentials_create(creds1=%p, creds2=%p, "
+      "grpc_composite_call_credentials_create(creds1=%p, creds2=%p, "
       "reserved=%p)",
       3, (creds1, creds2, reserved));
   GPR_ASSERT(reserved == NULL);
   GPR_ASSERT(creds1 != NULL);
   GPR_ASSERT(creds2 != NULL);
-  c = gpr_malloc(sizeof(grpc_composite_credentials));
-  memset(c, 0, sizeof(grpc_composite_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_COMPOSITE;
-  c->base.vtable = &composite_credentials_vtable;
+  c = gpr_malloc(sizeof(grpc_composite_call_credentials));
+  memset(c, 0, sizeof(grpc_composite_call_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE;
+  c->base.vtable = &composite_call_credentials_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   creds1_array = get_creds_array(&creds1);
   creds2_array = get_creds_array(&creds2);
   c->inner.num_creds = creds1_array.num_creds + creds2_array.num_creds;
-  creds_array_byte_size = c->inner.num_creds * sizeof(grpc_credentials *);
+  creds_array_byte_size = c->inner.num_creds * sizeof(grpc_call_credentials *);
   c->inner.creds_array = gpr_malloc(creds_array_byte_size);
   memset(c->inner.creds_array, 0, creds_array_byte_size);
   for (i = 0; i < creds1_array.num_creds; i++) {
-    grpc_credentials *cur_creds = creds1_array.creds_array[i];
-    if (!grpc_credentials_has_request_metadata_only(cur_creds)) {
-      if (c->connector_creds == NULL) {
-        c->connector_creds = cur_creds;
-      } else {
-        gpr_log(GPR_ERROR, "Cannot compose multiple connector credentials.");
-        goto fail;
-      }
-    }
-    c->inner.creds_array[i] = grpc_credentials_ref(cur_creds);
+    grpc_call_credentials *cur_creds = creds1_array.creds_array[i];
+    c->inner.creds_array[i] = grpc_call_credentials_ref(cur_creds);
   }
   for (i = 0; i < creds2_array.num_creds; i++) {
-    grpc_credentials *cur_creds = creds2_array.creds_array[i];
-    if (!grpc_credentials_has_request_metadata_only(cur_creds)) {
-      if (c->connector_creds == NULL) {
-        c->connector_creds = cur_creds;
-      } else {
-        gpr_log(GPR_ERROR, "Cannot compose multiple connector credentials.");
-        goto fail;
-      }
-    }
+    grpc_call_credentials *cur_creds = creds2_array.creds_array[i];
     c->inner.creds_array[i + creds1_array.num_creds] =
-        grpc_credentials_ref(cur_creds);
+        grpc_call_credentials_ref(cur_creds);
   }
   return &c->base;
-
-fail:
-  grpc_credentials_unref(&c->base);
-  return NULL;
 }
 
-const grpc_credentials_array *grpc_composite_credentials_get_credentials(
-    grpc_credentials *creds) {
-  const grpc_composite_credentials *c =
-      (const grpc_composite_credentials *)creds;
-  GPR_ASSERT(strcmp(creds->type, GRPC_CREDENTIALS_TYPE_COMPOSITE) == 0);
+const grpc_call_credentials_array *
+grpc_composite_call_credentials_get_credentials(grpc_call_credentials *creds) {
+  const grpc_composite_call_credentials *c =
+      (const grpc_composite_call_credentials *)creds;
+  GPR_ASSERT(strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0);
   return &c->inner;
 }
 
-grpc_credentials *grpc_credentials_contains_type(
-    grpc_credentials *creds, const char *type,
-    grpc_credentials **composite_creds) {
+grpc_call_credentials *grpc_credentials_contains_type(
+    grpc_call_credentials *creds, const char *type,
+    grpc_call_credentials **composite_creds) {
   size_t i;
   if (strcmp(creds->type, type) == 0) {
     if (composite_creds != NULL) *composite_creds = NULL;
     return creds;
-  } else if (strcmp(creds->type, GRPC_CREDENTIALS_TYPE_COMPOSITE) == 0) {
-    const grpc_credentials_array *inner_creds_array =
-        grpc_composite_credentials_get_credentials(creds);
+  } else if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
+    const grpc_call_credentials_array *inner_creds_array =
+        grpc_composite_call_credentials_get_credentials(creds);
     for (i = 0; i < inner_creds_array->num_creds; i++) {
       if (strcmp(type, inner_creds_array->creds_array[i]->type) == 0) {
         if (composite_creds != NULL) *composite_creds = creds;
@@ -1215,30 +1087,26 @@ grpc_credentials *grpc_credentials_contains_type(
 
 /* -- IAM credentials. -- */
 
-static void iam_destruct(grpc_credentials *creds) {
+static void iam_destruct(grpc_call_credentials *creds) {
   grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
   grpc_credentials_md_store_unref(c->iam_md);
 }
 
-static int iam_has_request_metadata(const grpc_credentials *creds) { return 1; }
-
-static int iam_has_request_metadata_only(const grpc_credentials *creds) {
-  return 1;
-}
-
-static void iam_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void iam_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                     grpc_call_credentials *creds,
+                                     grpc_pollset *pollset,
+                                     grpc_auth_metadata_context context,
+                                     grpc_credentials_metadata_cb cb,
+                                     void *user_data) {
   grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
   cb(exec_ctx, user_data, c->iam_md->entries, c->iam_md->num_entries,
      GRPC_CREDENTIALS_OK);
 }
 
-static grpc_credentials_vtable iam_vtable = {
-    iam_destruct, iam_has_request_metadata, iam_has_request_metadata_only,
-    iam_get_request_metadata, NULL};
+static grpc_call_credentials_vtable iam_vtable = {iam_destruct,
+                                                  iam_get_request_metadata};
 
-grpc_credentials *grpc_google_iam_credentials_create(
+grpc_call_credentials *grpc_google_iam_credentials_create(
     const char *token, const char *authority_selector, void *reserved) {
   grpc_google_iam_credentials *c;
   GRPC_API_TRACE(
@@ -1250,7 +1118,7 @@ grpc_credentials *grpc_google_iam_credentials_create(
   GPR_ASSERT(authority_selector != NULL);
   c = gpr_malloc(sizeof(grpc_google_iam_credentials));
   memset(c, 0, sizeof(grpc_google_iam_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_IAM;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_IAM;
   c->base.vtable = &iam_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->iam_md = grpc_credentials_md_store_create(2);
@@ -1268,21 +1136,13 @@ typedef struct {
   grpc_credentials_metadata_cb cb;
 } grpc_metadata_plugin_request;
 
-static void plugin_destruct(grpc_credentials *creds) {
+static void plugin_destruct(grpc_call_credentials *creds) {
   grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
   if (c->plugin.state != NULL && c->plugin.destroy != NULL) {
     c->plugin.destroy(c->plugin.state);
   }
 }
 
-static int plugin_has_request_metadata(const grpc_credentials *creds) {
-  return 1;
-}
-
-static int plugin_has_request_metadata_only(const grpc_credentials *creds) {
-  return 1;
-}
-
 static void plugin_md_request_metadata_ready(void *request,
                                              const grpc_metadata *md,
                                              size_t num_md,
@@ -1321,34 +1181,94 @@ static void plugin_md_request_metadata_ready(void *request,
   grpc_exec_ctx_finish(&exec_ctx);
 }
 
-static void plugin_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void plugin_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                        grpc_call_credentials *creds,
+                                        grpc_pollset *pollset,
+                                        grpc_auth_metadata_context context,
+                                        grpc_credentials_metadata_cb cb,
+                                        void *user_data) {
   grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
   if (c->plugin.get_metadata != NULL) {
     grpc_metadata_plugin_request *request = gpr_malloc(sizeof(*request));
     memset(request, 0, sizeof(*request));
     request->user_data = user_data;
     request->cb = cb;
-    c->plugin.get_metadata(c->plugin.state, service_url,
+    c->plugin.get_metadata(c->plugin.state, context,
                            plugin_md_request_metadata_ready, request);
   } else {
     cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK);
   }
 }
 
-static grpc_credentials_vtable plugin_vtable = {
-    plugin_destruct, plugin_has_request_metadata,
-    plugin_has_request_metadata_only, plugin_get_request_metadata, NULL};
+static grpc_call_credentials_vtable plugin_vtable = {
+    plugin_destruct, plugin_get_request_metadata};
 
-grpc_credentials *grpc_metadata_credentials_create_from_plugin(
+grpc_call_credentials *grpc_metadata_credentials_create_from_plugin(
     grpc_metadata_credentials_plugin plugin, void *reserved) {
   grpc_plugin_credentials *c = gpr_malloc(sizeof(*c));
+  GRPC_API_TRACE("grpc_metadata_credentials_create_from_plugin(reserved=%p)", 1,
+                 (reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(*c));
-  c->base.type = GRPC_CREDENTIALS_TYPE_METADATA_PLUGIN;
+  c->base.type = plugin.type;
   c->base.vtable = &plugin_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->plugin = plugin;
   return &c->base;
 }
+
+/* -- Composite channel credentials. -- */
+
+static void composite_channel_destruct(grpc_channel_credentials *creds) {
+  grpc_composite_channel_credentials *c =
+      (grpc_composite_channel_credentials *)creds;
+  grpc_channel_credentials_unref(c->inner_creds);
+  grpc_call_credentials_unref(c->call_creds);
+}
+
+static grpc_security_status composite_channel_create_security_connector(
+    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
+    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+  grpc_composite_channel_credentials *c =
+      (grpc_composite_channel_credentials *)creds;
+  grpc_security_status status = GRPC_SECURITY_ERROR;
+
+  GPR_ASSERT(c->inner_creds != NULL && c->call_creds != NULL &&
+             c->inner_creds->vtable != NULL &&
+             c->inner_creds->vtable->create_security_connector != NULL);
+  /* If we are passed a call_creds, create a call composite to pass it
+     downstream. */
+  if (call_creds != NULL) {
+    grpc_call_credentials *composite_call_creds =
+        grpc_composite_call_credentials_create(c->call_creds, call_creds, NULL);
+    status = c->inner_creds->vtable->create_security_connector(
+        c->inner_creds, composite_call_creds, target, args, sc, new_args);
+    grpc_call_credentials_unref(composite_call_creds);
+  } else {
+    status = c->inner_creds->vtable->create_security_connector(
+        c->inner_creds, c->call_creds, target, args, sc, new_args);
+  }
+  return status;
+}
+
+static grpc_channel_credentials_vtable composite_channel_credentials_vtable = {
+    composite_channel_destruct, composite_channel_create_security_connector};
+
+grpc_channel_credentials *grpc_composite_channel_credentials_create(
+    grpc_channel_credentials *channel_creds, grpc_call_credentials *call_creds,
+    void *reserved) {
+  grpc_composite_channel_credentials *c = gpr_malloc(sizeof(*c));
+  memset(c, 0, sizeof(*c));
+  GPR_ASSERT(channel_creds != NULL && call_creds != NULL && reserved == NULL);
+  GRPC_API_TRACE(
+      "grpc_composite_channel_credentials_create(channel_creds=%p, "
+      "call_creds=%p, reserved=%p)",
+      3, (channel_creds, call_creds, reserved));
+  c->base.type = channel_creds->type;
+  c->base.vtable = &composite_channel_credentials_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->inner_creds = grpc_channel_credentials_ref(channel_creds);
+  c->call_creds = grpc_call_credentials_ref(call_creds);
+  return &c->base;
+}

src/core/security/credentials.h

@@ -34,7 +34,7 @@
 #ifndef GRPC_INTERNAL_CORE_SECURITY_CREDENTIALS_H
 #define GRPC_INTERNAL_CORE_SECURITY_CREDENTIALS_H
 
-#include "src/core/transport/stream_op.h"
+#include "src/core/transport/metadata_batch.h"
 #include <grpc/grpc.h>
 #include <grpc/grpc_security.h>
 #include <grpc/support/sync.h>
@@ -54,15 +54,16 @@ typedef enum {
 
 #define GRPC_FAKE_TRANSPORT_SECURITY_TYPE "fake"
 
-#define GRPC_CREDENTIALS_TYPE_SSL "Ssl"
-#define GRPC_CREDENTIALS_TYPE_OAUTH2 "Oauth2"
-#define GRPC_CREDENTIALS_TYPE_METADATA_PLUGIN "Plugin"
-#define GRPC_CREDENTIALS_TYPE_JWT "Jwt"
-#define GRPC_CREDENTIALS_TYPE_IAM "Iam"
-#define GRPC_CREDENTIALS_TYPE_COMPOSITE "Composite"
-#define GRPC_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY "FakeTransportSecurity"
+#define GRPC_CHANNEL_CREDENTIALS_TYPE_SSL "Ssl"
+#define GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY \
+  "FakeTransportSecurity"
 
-#define GRPC_AUTHORIZATION_METADATA_KEY "Authorization"
+#define GRPC_CALL_CREDENTIALS_TYPE_OAUTH2 "Oauth2"
+#define GRPC_CALL_CREDENTIALS_TYPE_JWT "Jwt"
+#define GRPC_CALL_CREDENTIALS_TYPE_IAM "Iam"
+#define GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE "Composite"
+
+#define GRPC_AUTHORIZATION_METADATA_KEY "authorization"
 #define GRPC_IAM_AUTHORIZATION_TOKEN_METADATA_KEY \
   "x-goog-iam-authorization-token"
 #define GRPC_IAM_AUTHORITY_SELECTOR_METADATA_KEY "x-goog-iam-authority-selector"
@@ -87,6 +88,41 @@ typedef enum {
 #define GRPC_REFRESH_TOKEN_POST_BODY_FORMAT_STRING \
   "client_id=%s&client_secret=%s&refresh_token=%s&grant_type=refresh_token"
 
+/* --- Google utils --- */
+
+/* It is the caller's responsibility to gpr_free the result if not NULL. */
+char *grpc_get_well_known_google_credentials_file_path(void);
+
+/* --- grpc_channel_credentials. --- */
+
+typedef struct {
+  void (*destruct)(grpc_channel_credentials *c);
+
+  grpc_security_status (*create_security_connector)(
+      grpc_channel_credentials *c, grpc_call_credentials *call_creds,
+      const char *target, const grpc_channel_args *args,
+      grpc_channel_security_connector **sc, grpc_channel_args **new_args);
+} grpc_channel_credentials_vtable;
+
+struct grpc_channel_credentials {
+  const grpc_channel_credentials_vtable *vtable;
+  const char *type;
+  gpr_refcount refcount;
+};
+
+grpc_channel_credentials *grpc_channel_credentials_ref(
+    grpc_channel_credentials *creds);
+void grpc_channel_credentials_unref(grpc_channel_credentials *creds);
+
+/* Creates a security connector for the channel. May also create new channel
+   args for the channel to be used in place of the passed in const args if
+   returned non NULL. In that case the caller is responsible for destroying
+   new_args after channel creation. */
+grpc_security_status grpc_channel_credentials_create_security_connector(
+    grpc_channel_credentials *creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args);
+
 /* --- grpc_credentials_md. --- */
 
 typedef struct {
@@ -113,16 +149,7 @@ grpc_credentials_md_store *grpc_credentials_md_store_ref(
     grpc_credentials_md_store *store);
 void grpc_credentials_md_store_unref(grpc_credentials_md_store *store);
 
-/* --- grpc_credentials. --- */
-
-/* Creates a fake transport security credentials object for testing. */
-grpc_credentials *grpc_fake_transport_security_credentials_create(void);
-/* Creates a fake server transport security credentials object for testing. */
-grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
-    void);
-
-/* It is the caller's responsibility to gpr_free the result if not NULL. */
-char *grpc_get_well_known_google_credentials_file_path(void);
+/* --- grpc_call_credentials. --- */
 
 typedef void (*grpc_credentials_metadata_cb)(grpc_exec_ctx *exec_ctx,
                                              void *user_data,
@@ -131,57 +158,43 @@ typedef void (*grpc_credentials_metadata_cb)(grpc_exec_ctx *exec_ctx,
                                              grpc_credentials_status status);
 
 typedef struct {
-  void (*destruct)(grpc_credentials *c);
-  int (*has_request_metadata)(const grpc_credentials *c);
-  int (*has_request_metadata_only)(const grpc_credentials *c);
-  void (*get_request_metadata)(grpc_exec_ctx *exec_ctx, grpc_credentials *c,
-                               grpc_pollset *pollset, const char *service_url,
+  void (*destruct)(grpc_call_credentials *c);
+  void (*get_request_metadata)(grpc_exec_ctx *exec_ctx,
+                               grpc_call_credentials *c, grpc_pollset *pollset,
+                               grpc_auth_metadata_context context,
                                grpc_credentials_metadata_cb cb,
                                void *user_data);
-  grpc_security_status (*create_security_connector)(
-      grpc_credentials *c, const char *target, const grpc_channel_args *args,
-      grpc_credentials *request_metadata_creds,
-      grpc_channel_security_connector **sc, grpc_channel_args **new_args);
-} grpc_credentials_vtable;
+} grpc_call_credentials_vtable;
 
-struct grpc_credentials {
-  const grpc_credentials_vtable *vtable;
+struct grpc_call_credentials {
+  const grpc_call_credentials_vtable *vtable;
   const char *type;
   gpr_refcount refcount;
 };
 
-grpc_credentials *grpc_credentials_ref(grpc_credentials *creds);
-void grpc_credentials_unref(grpc_credentials *creds);
-int grpc_credentials_has_request_metadata(grpc_credentials *creds);
-int grpc_credentials_has_request_metadata_only(grpc_credentials *creds);
-void grpc_credentials_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data);
-
-/* Creates a security connector for the channel. May also create new channel
-   args for the channel to be used in place of the passed in const args if
-   returned non NULL. In that case the caller is responsible for destroying
-   new_args after channel creation. */
-grpc_security_status grpc_credentials_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args);
+grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds);
+void grpc_call_credentials_unref(grpc_call_credentials *creds);
+void grpc_call_credentials_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data);
 
 typedef struct {
-  grpc_credentials **creds_array;
+  grpc_call_credentials **creds_array;
   size_t num_creds;
-} grpc_credentials_array;
+} grpc_call_credentials_array;
 
-const grpc_credentials_array *grpc_composite_credentials_get_credentials(
-    grpc_credentials *composite_creds);
+const grpc_call_credentials_array *
+grpc_composite_call_credentials_get_credentials(
+    grpc_call_credentials *composite_creds);
 
 /* Returns creds if creds is of the specified type or the inner creds of the
    specified type (if found), if the creds is of type COMPOSITE.
    If composite_creds is not NULL, *composite_creds will point to creds if of
    type COMPOSITE in case of success. */
-grpc_credentials *grpc_credentials_contains_type(
-    grpc_credentials *creds, const char *type,
-    grpc_credentials **composite_creds);
+grpc_call_credentials *grpc_credentials_contains_type(
+    grpc_call_credentials *creds, const char *type,
+    grpc_call_credentials **composite_creds);
 
 /* Exposed for testing only. */
 grpc_credentials_status
@@ -192,19 +205,19 @@ void grpc_flush_cached_google_default_credentials(void);
 
 /* Metadata-only credentials with the specified key and value where
    asynchronicity can be simulated for testing. */
-grpc_credentials *grpc_md_only_test_credentials_create(const char *md_key,
-                                                       const char *md_value,
-                                                       int is_async);
+grpc_call_credentials *grpc_md_only_test_credentials_create(
+    const char *md_key, const char *md_value, int is_async);
 
 /* Private constructor for jwt credentials from an already parsed json key.
    Takes ownership of the key. */
-grpc_credentials *
+grpc_call_credentials *
 grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
     grpc_auth_json_key key, gpr_timespec token_lifetime);
 
 /* Private constructor for refresh token credentials from an already parsed
    refresh token. Takes ownership of the refresh token. */
-grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
+grpc_call_credentials *
+grpc_refresh_token_credentials_create_from_auth_refresh_token(
     grpc_auth_refresh_token token);
 
 /* --- grpc_server_credentials. --- */
@@ -237,10 +250,18 @@ grpc_server_credentials *grpc_server_credentials_from_arg(const grpc_arg *arg);
 grpc_server_credentials *grpc_find_server_credentials_in_args(
     const grpc_channel_args *args);
 
+/* -- Fake transport security credentials. -- */
+
+/* Creates a fake transport security credentials object for testing. */
+grpc_channel_credentials *grpc_fake_transport_security_credentials_create(void);
+/* Creates a fake server transport security credentials object for testing. */
+grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
+    void);
+
 /* -- Ssl credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_channel_credentials base;
   grpc_ssl_config config;
 } grpc_ssl_credentials;
 
@@ -249,10 +270,18 @@ typedef struct {
   grpc_ssl_server_config config;
 } grpc_ssl_server_credentials;
 
+/* -- Channel composite credentials. -- */
+
+typedef struct {
+  grpc_channel_credentials base;
+  grpc_channel_credentials *inner_creds;
+  grpc_call_credentials *call_creds;
+} grpc_composite_channel_credentials;
+
 /* -- Jwt credentials -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
 
   /* Have a simple cache for now with just 1 entry. We could have a map based on
      the service_url for a more sophisticated one. */
@@ -283,7 +312,7 @@ typedef void (*grpc_fetch_oauth2_func)(grpc_exec_ctx *exec_ctx,
                                        gpr_timespec deadline);
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   gpr_mu mu;
   grpc_credentials_md_store *access_token_md;
   gpr_timespec token_expiration;
@@ -301,14 +330,14 @@ typedef struct {
 /* -- Oauth2 Access Token credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_credentials_md_store *access_token_md;
 } grpc_access_token_credentials;
 
 /* --  Metadata-only Test credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_credentials_md_store *md_store;
   int is_async;
 } grpc_md_only_test_credentials;
@@ -316,22 +345,21 @@ typedef struct {
 /* -- GoogleIAM credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_credentials_md_store *iam_md;
 } grpc_google_iam_credentials;
 
 /* -- Composite credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
-  grpc_credentials_array inner;
-  grpc_credentials *connector_creds;
-} grpc_composite_credentials;
+  grpc_call_credentials base;
+  grpc_call_credentials_array inner;
+} grpc_composite_call_credentials;
 
 /* -- Plugin credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_metadata_credentials_plugin plugin;
   grpc_credentials_md_store *plugin_md;
 } grpc_plugin_credentials;

src/core/security/google_default_credentials.c

@@ -50,7 +50,7 @@
 
 /* -- Default credentials. -- */
 
-static grpc_credentials *default_credentials = NULL;
+static grpc_channel_credentials *default_credentials = NULL;
 static int compute_engine_detection_done = 0;
 static gpr_mu g_mu;
 static gpr_once g_once = GPR_ONCE_INIT;
@@ -138,11 +138,11 @@ static int is_stack_running_on_compute_engine(void) {
 }
 
 /* Takes ownership of creds_path if not NULL. */
-static grpc_credentials *create_default_creds_from_path(char *creds_path) {
+static grpc_call_credentials *create_default_creds_from_path(char *creds_path) {
   grpc_json *json = NULL;
   grpc_auth_json_key key;
   grpc_auth_refresh_token token;
-  grpc_credentials *result = NULL;
+  grpc_call_credentials *result = NULL;
   gpr_slice creds_data = gpr_empty_slice();
   int file_ok = 0;
   if (creds_path == NULL) goto end;
@@ -176,9 +176,9 @@ end:
   return result;
 }
 
-grpc_credentials *grpc_google_default_credentials_create(void) {
-  grpc_credentials *result = NULL;
-  int serving_cached_credentials = 0;
+grpc_channel_credentials *grpc_google_default_credentials_create(void) {
+  grpc_channel_credentials *result = NULL;
+  grpc_call_credentials *call_creds = NULL;
 
   GRPC_API_TRACE("grpc_google_default_credentials_create(void)", 0, ());
 
@@ -187,20 +187,19 @@ grpc_credentials *grpc_google_default_credentials_create(void) {
   gpr_mu_lock(&g_mu);
 
   if (default_credentials != NULL) {
-    result = grpc_credentials_ref(default_credentials);
-    serving_cached_credentials = 1;
+    result = grpc_channel_credentials_ref(default_credentials);
     goto end;
   }
 
   /* First, try the environment variable. */
-  result = create_default_creds_from_path(
+  call_creds = create_default_creds_from_path(
       gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR));
-  if (result != NULL) goto end;
+  if (call_creds != NULL) goto end;
 
   /* Then the well-known file. */
-  result = create_default_creds_from_path(
+  call_creds = create_default_creds_from_path(
       grpc_get_well_known_google_credentials_file_path());
-  if (result != NULL) goto end;
+  if (call_creds != NULL) goto end;
 
   /* At last try to see if we're on compute engine (do the detection only once
      since it requires a network test). */
@@ -208,21 +207,28 @@ grpc_credentials *grpc_google_default_credentials_create(void) {
     int need_compute_engine_creds = is_stack_running_on_compute_engine();
     compute_engine_detection_done = 1;
     if (need_compute_engine_creds) {
-      result = grpc_google_compute_engine_credentials_create(NULL);
+      call_creds = grpc_google_compute_engine_credentials_create(NULL);
     }
   }
 
 end:
-  if (!serving_cached_credentials && result != NULL) {
-    /* Blend with default ssl credentials and add a global reference so that it
-       can be cached and re-served. */
-    grpc_credentials *ssl_creds = grpc_ssl_credentials_create(NULL, NULL, NULL);
-    default_credentials = grpc_credentials_ref(
-        grpc_composite_credentials_create(ssl_creds, result, NULL));
-    GPR_ASSERT(default_credentials != NULL);
-    grpc_credentials_unref(ssl_creds);
-    grpc_credentials_unref(result);
-    result = default_credentials;
+  if (result == NULL) {
+    if (call_creds != NULL) {
+      /* Blend with default ssl credentials and add a global reference so that
+         it
+         can be cached and re-served. */
+      grpc_channel_credentials *ssl_creds =
+          grpc_ssl_credentials_create(NULL, NULL, NULL);
+      default_credentials = grpc_channel_credentials_ref(
+          grpc_composite_channel_credentials_create(ssl_creds, call_creds,
+                                                    NULL));
+      GPR_ASSERT(default_credentials != NULL);
+      grpc_channel_credentials_unref(ssl_creds);
+      grpc_call_credentials_unref(call_creds);
+      result = default_credentials;
+    } else {
+      gpr_log(GPR_ERROR, "Could not create google default credentials.");
+    }
   }
   gpr_mu_unlock(&g_mu);
   return result;
@@ -232,7 +238,7 @@ void grpc_flush_cached_google_default_credentials(void) {
   gpr_once_init(&g_once, init_default_credentials);
   gpr_mu_lock(&g_mu);
   if (default_credentials != NULL) {
-    grpc_credentials_unref(default_credentials);
+    grpc_channel_credentials_unref(default_credentials);
     default_credentials = NULL;
   }
   gpr_mu_unlock(&g_mu);

src/core/security/security_connector.c

@@ -203,16 +203,6 @@ grpc_security_connector *grpc_find_security_connector_in_args(
   return NULL;
 }
 
-static int check_request_metadata_creds(grpc_credentials *creds) {
-  if (creds != NULL && !grpc_credentials_has_request_metadata(creds)) {
-    gpr_log(GPR_ERROR,
-            "Incompatible credentials for channel security connector: needs to "
-            "set request metadata.");
-    return 0;
-  }
-  return 1;
-}
-
 /* -- Fake implementation. -- */
 
 typedef struct {
@@ -222,7 +212,7 @@ typedef struct {
 
 static void fake_channel_destroy(grpc_security_connector *sc) {
   grpc_channel_security_connector *c = (grpc_channel_security_connector *)sc;
-  grpc_credentials_unref(c->request_metadata_creds);
+  grpc_call_credentials_unref(c->request_metadata_creds);
   GRPC_AUTH_CONTEXT_UNREF(sc->auth_context, "connector");
   gpr_free(sc);
 }
@@ -306,7 +296,8 @@ static grpc_security_connector_vtable fake_server_vtable = {
     fake_server_destroy, fake_server_do_handshake, fake_check_peer};
 
 grpc_channel_security_connector *grpc_fake_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, int call_host_check_is_async) {
+    grpc_call_credentials *request_metadata_creds,
+    int call_host_check_is_async) {
   grpc_fake_channel_security_connector *c =
       gpr_malloc(sizeof(grpc_fake_channel_security_connector));
   memset(c, 0, sizeof(grpc_fake_channel_security_connector));
@@ -314,8 +305,8 @@ grpc_channel_security_connector *grpc_fake_channel_security_connector_create(
   c->base.base.is_client_side = 1;
   c->base.base.url_scheme = GRPC_FAKE_SECURITY_URL_SCHEME;
   c->base.base.vtable = &fake_channel_vtable;
-  GPR_ASSERT(check_request_metadata_creds(request_metadata_creds));
-  c->base.request_metadata_creds = grpc_credentials_ref(request_metadata_creds);
+  c->base.request_metadata_creds =
+      grpc_call_credentials_ref(request_metadata_creds);
   c->base.check_call_host = fake_channel_check_call_host;
   c->call_host_check_is_async = call_host_check_is_async;
   return &c->base;
@@ -349,7 +340,7 @@ typedef struct {
 static void ssl_channel_destroy(grpc_security_connector *sc) {
   grpc_ssl_channel_security_connector *c =
       (grpc_ssl_channel_security_connector *)sc;
-  grpc_credentials_unref(c->base.request_metadata_creds);
+  grpc_call_credentials_unref(c->base.request_metadata_creds);
   if (c->handshaker_factory != NULL) {
     tsi_ssl_handshaker_factory_destroy(c->handshaker_factory);
   }
@@ -580,9 +571,9 @@ size_t grpc_get_default_ssl_roots(const unsigned char **pem_root_certs) {
 }
 
 grpc_security_status grpc_ssl_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, const grpc_ssl_config *config,
-    const char *target_name, const char *overridden_target_name,
-    grpc_channel_security_connector **sc) {
+    grpc_call_credentials *request_metadata_creds,
+    const grpc_ssl_config *config, const char *target_name,
+    const char *overridden_target_name, grpc_channel_security_connector **sc) {
   size_t num_alpn_protocols = grpc_chttp2_num_alpn_versions();
   const unsigned char **alpn_protocol_strings =
       gpr_malloc(sizeof(const char *) * num_alpn_protocols);
@@ -606,9 +597,6 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
     gpr_log(GPR_ERROR, "An ssl channel needs a config and a target name.");
     goto error;
   }
-  if (!check_request_metadata_creds(request_metadata_creds)) {
-    goto error;
-  }
   if (config->pem_root_certs == NULL) {
     pem_root_certs_size = grpc_get_default_ssl_roots(&pem_root_certs);
     if (pem_root_certs == NULL || pem_root_certs_size == 0) {
@@ -627,7 +615,8 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
   c->base.base.vtable = &ssl_channel_vtable;
   c->base.base.is_client_side = 1;
   c->base.base.url_scheme = GRPC_SSL_URL_SCHEME;
-  c->base.request_metadata_creds = grpc_credentials_ref(request_metadata_creds);
+  c->base.request_metadata_creds =
+      grpc_call_credentials_ref(request_metadata_creds);
   c->base.check_call_host = ssl_channel_check_call_host;
   gpr_split_host_port(target_name, &c->target_name, &port);
   gpr_free(port);

src/core/security/security_connector.h

@@ -86,6 +86,7 @@ struct grpc_security_connector {
   int is_client_side;
   const char *url_scheme;
   grpc_auth_context *auth_context; /* Populated after the peer is checked. */
+  const grpc_channel_args *channel_args; /* Server side only. */
 };
 
 /* Refcounting. */
@@ -145,7 +146,7 @@ typedef struct grpc_channel_security_connector grpc_channel_security_connector;
 
 struct grpc_channel_security_connector {
   grpc_security_connector base; /* requires is_client_side to be non 0. */
-  grpc_credentials *request_metadata_creds;
+  grpc_call_credentials *request_metadata_creds;
   grpc_security_status (*check_call_host)(grpc_exec_ctx *exec_ctx,
                                           grpc_channel_security_connector *sc,
                                           const char *host,
@@ -167,7 +168,8 @@ grpc_security_status grpc_channel_security_connector_check_call_host(
 /* For TESTING ONLY!
    Creates a fake connector that emulates real channel security.  */
 grpc_channel_security_connector *grpc_fake_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, int call_host_check_is_async);
+    grpc_call_credentials *request_metadata_creds,
+    int call_host_check_is_async);
 
 /* For TESTING ONLY!
    Creates a fake connector that emulates real server security.  */
@@ -197,9 +199,9 @@ typedef struct {
   specific error code otherwise.
 */
 grpc_security_status grpc_ssl_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, const grpc_ssl_config *config,
-    const char *target_name, const char *overridden_target_name,
-    grpc_channel_security_connector **sc);
+    grpc_call_credentials *request_metadata_creds,
+    const grpc_ssl_config *config, const char *target_name,
+    const char *overridden_target_name, grpc_channel_security_connector **sc);
 
 /* Gets the default ssl roots. */
 size_t grpc_get_default_ssl_roots(const unsigned char **pem_root_certs);

src/core/security/security_context.c

@@ -46,7 +46,7 @@
 /* --- grpc_call --- */
 
 grpc_call_error grpc_call_set_credentials(grpc_call *call,
-                                          grpc_credentials *creds) {
+                                          grpc_call_credentials *creds) {
   grpc_client_security_context *ctx = NULL;
   GRPC_API_TRACE("grpc_call_set_credentials(call=%p, creds=%p)", 2,
                  (call, creds));
@@ -54,20 +54,16 @@ grpc_call_error grpc_call_set_credentials(grpc_call *call,
     gpr_log(GPR_ERROR, "Method is client-side only.");
     return GRPC_CALL_ERROR_NOT_ON_SERVER;
   }
-  if (creds != NULL && !grpc_credentials_has_request_metadata_only(creds)) {
-    gpr_log(GPR_ERROR, "Incompatible credentials to set on a call.");
-    return GRPC_CALL_ERROR;
-  }
   ctx = (grpc_client_security_context *)grpc_call_context_get(
       call, GRPC_CONTEXT_SECURITY);
   if (ctx == NULL) {
     ctx = grpc_client_security_context_create();
-    ctx->creds = grpc_credentials_ref(creds);
+    ctx->creds = grpc_call_credentials_ref(creds);
     grpc_call_context_set(call, GRPC_CONTEXT_SECURITY, ctx,
                           grpc_client_security_context_destroy);
   } else {
-    grpc_credentials_unref(ctx->creds);
-    ctx->creds = grpc_credentials_ref(creds);
+    grpc_call_credentials_unref(ctx->creds);
+    ctx->creds = grpc_call_credentials_ref(creds);
   }
   return GRPC_CALL_OK;
 }
@@ -101,7 +97,7 @@ grpc_client_security_context *grpc_client_security_context_create(void) {
 
 void grpc_client_security_context_destroy(void *ctx) {
   grpc_client_security_context *c = (grpc_client_security_context *)ctx;
-  grpc_credentials_unref(c->creds);
+  grpc_call_credentials_unref(c->creds);
   GRPC_AUTH_CONTEXT_UNREF(c->auth_context, "client_security_context");
   gpr_free(ctx);
 }
@@ -324,8 +320,7 @@ grpc_arg grpc_auth_context_to_arg(grpc_auth_context *p) {
   return arg;
 }
 
-grpc_auth_context *grpc_auth_context_from_arg(
-    const grpc_arg *arg) {
+grpc_auth_context *grpc_auth_context_from_arg(const grpc_arg *arg) {
   if (strcmp(arg->key, GRPC_AUTH_CONTEXT_ARG) != 0) return NULL;
   if (arg->type != GRPC_ARG_POINTER) {
     gpr_log(GPR_ERROR, "Invalid type %d for arg %s", arg->type,
@@ -340,8 +335,7 @@ grpc_auth_context *grpc_find_auth_context_in_args(
   size_t i;
   if (args == NULL) return NULL;
   for (i = 0; i < args->num_args; i++) {
-    grpc_auth_context *p =
-        grpc_auth_context_from_arg(&args->args[i]);
+    grpc_auth_context *p = grpc_auth_context_from_arg(&args->args[i]);
     if (p != NULL) return p;
   }
   return NULL;

src/core/security/security_context.h

@@ -85,7 +85,7 @@ void grpc_auth_property_reset(grpc_auth_property *property);
    Internal client-side security context. */
 
 typedef struct {
-  grpc_credentials *creds;
+  grpc_call_credentials *creds;
   grpc_auth_context *auth_context;
 } grpc_client_security_context;
 

src/core/security/server_auth_filter.c

@@ -41,8 +41,7 @@
 #include <grpc/support/log.h>
 
 typedef struct call_data {
-  gpr_uint8 got_client_metadata;
-  grpc_stream_op_buffer *recv_ops;
+  grpc_metadata_batch *recv_initial_metadata;
   /* Closure to call when finished with the auth_on_recv hook. */
   grpc_closure *on_done_recv;
   /* Receive closures are chained: we inject this closure as the on_done_recv
@@ -53,14 +52,12 @@ typedef struct call_data {
   grpc_metadata_array md;
   const grpc_metadata *consumed_md;
   size_t num_consumed_md;
-  grpc_stream_op *md_op;
   grpc_auth_context *auth_context;
 } call_data;
 
 typedef struct channel_data {
   grpc_auth_context *auth_context;
   grpc_server_credentials *creds;
-  grpc_mdctx *mdctx;
 } channel_data;
 
 static grpc_metadata_array metadata_batch_to_md_array(
@@ -128,20 +125,28 @@ static void on_md_processing_done(
   if (status == GRPC_STATUS_OK) {
     calld->consumed_md = consumed_md;
     calld->num_consumed_md = num_consumed_md;
-    grpc_metadata_batch_filter(&calld->md_op->data.metadata, remove_consumed_md,
+    grpc_metadata_batch_filter(calld->recv_initial_metadata, remove_consumed_md,
                                elem);
     grpc_metadata_array_destroy(&calld->md);
     calld->on_done_recv->cb(&exec_ctx, calld->on_done_recv->cb_arg, 1);
   } else {
     gpr_slice message;
+    grpc_transport_stream_op close_op;
+    memset(&close_op, 0, sizeof(close_op));
     grpc_metadata_array_destroy(&calld->md);
     error_details = error_details != NULL
                         ? error_details
                         : "Authentication metadata processing failed.";
     message = gpr_slice_from_copied_string(error_details);
-    grpc_sopb_reset(calld->recv_ops);
-    grpc_transport_stream_op_add_close(&calld->transport_op, status, &message);
-    grpc_call_next_op(&exec_ctx, elem, &calld->transport_op);
+    calld->transport_op.send_initial_metadata = NULL;
+    if (calld->transport_op.send_message != NULL) {
+      grpc_byte_stream_destroy(calld->transport_op.send_message);
+      calld->transport_op.send_message = NULL;
+    }
+    calld->transport_op.send_trailing_metadata = NULL;
+    grpc_transport_stream_op_add_close(&close_op, status, &message);
+    grpc_call_next_op(&exec_ctx, elem, &close_op);
+    calld->on_done_recv->cb(&exec_ctx, calld->on_done_recv->cb_arg, 0);
   }
 
   grpc_exec_ctx_finish(&exec_ctx);
@@ -153,16 +158,8 @@ static void auth_on_recv(grpc_exec_ctx *exec_ctx, void *user_data,
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   if (success) {
-    size_t i;
-    size_t nops = calld->recv_ops->nops;
-    grpc_stream_op *ops = calld->recv_ops->ops;
-    for (i = 0; i < nops; i++) {
-      grpc_stream_op *op = &ops[i];
-      if (op->type != GRPC_OP_METADATA || calld->got_client_metadata) continue;
-      calld->got_client_metadata = 1;
-      if (chand->creds->processor.process == NULL) continue;
-      calld->md_op = op;
-      calld->md = metadata_batch_to_md_array(&op->data.metadata);
+    if (chand->creds->processor.process != NULL) {
+      calld->md = metadata_batch_to_md_array(calld->recv_initial_metadata);
       chand->creds->processor.process(
           chand->creds->processor.state, calld->auth_context,
           calld->md.metadata, calld->md.count, on_md_processing_done, elem);
@@ -176,11 +173,11 @@ static void set_recv_ops_md_callbacks(grpc_call_element *elem,
                                       grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
 
-  if (op->recv_ops && !calld->got_client_metadata) {
+  if (op->recv_initial_metadata != NULL) {
     /* substitute our callback for the higher callback */
-    calld->recv_ops = op->recv_ops;
-    calld->on_done_recv = op->on_done_recv;
-    op->on_done_recv = &calld->auth_on_recv;
+    calld->recv_initial_metadata = op->recv_initial_metadata;
+    calld->on_done_recv = op->on_complete;
+    op->on_complete = &calld->auth_on_recv;
     calld->transport_op = *op;
   }
 }
@@ -199,8 +196,7 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           const void *server_transport_data,
-                           grpc_transport_stream_op *initial_op) {
+                           grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
@@ -210,47 +206,39 @@ static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   memset(calld, 0, sizeof(*calld));
   grpc_closure_init(&calld->auth_on_recv, auth_on_recv, elem);
 
-  GPR_ASSERT(initial_op && initial_op->context != NULL &&
-             initial_op->context[GRPC_CONTEXT_SECURITY].value == NULL);
-
-  /* Create a security context for the call and reference the auth context from
-     the channel. */
-  if (initial_op->context[GRPC_CONTEXT_SECURITY].value != NULL) {
-    initial_op->context[GRPC_CONTEXT_SECURITY].destroy(
-        initial_op->context[GRPC_CONTEXT_SECURITY].value);
+  if (args->context[GRPC_CONTEXT_SECURITY].value != NULL) {
+    args->context[GRPC_CONTEXT_SECURITY].destroy(
+        args->context[GRPC_CONTEXT_SECURITY].value);
   }
+
   server_ctx = grpc_server_security_context_create();
-  server_ctx->auth_context =
-      grpc_auth_context_create(chand->auth_context);
-  server_ctx->auth_context->pollset = initial_op->bind_pollset;
-  initial_op->context[GRPC_CONTEXT_SECURITY].value = server_ctx;
-  initial_op->context[GRPC_CONTEXT_SECURITY].destroy =
-      grpc_server_security_context_destroy;
+  server_ctx->auth_context = grpc_auth_context_create(chand->auth_context);
   calld->auth_context = server_ctx->auth_context;
 
-  /* Set the metadata callbacks. */
-  set_recv_ops_md_callbacks(elem, initial_op);
+  args->context[GRPC_CONTEXT_SECURITY].value = server_ctx;
+  args->context[GRPC_CONTEXT_SECURITY].destroy =
+      grpc_server_security_context_destroy;
 }
 
+static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                        grpc_pollset *pollset) {}
+
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
                               grpc_call_element *elem) {}
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem, grpc_channel *master,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
-  grpc_auth_context *auth_context = grpc_find_auth_context_in_args(args);
-  grpc_server_credentials *creds = grpc_find_server_credentials_in_args(args);
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
+  grpc_auth_context *auth_context =
+      grpc_find_auth_context_in_args(args->channel_args);
+  grpc_server_credentials *creds =
+      grpc_find_server_credentials_in_args(args->channel_args);
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
 
-  /* The first and the last filters tend to be implemented differently to
-     handle the case that there's no 'next' filter to call on the up or down
-     path */
-  GPR_ASSERT(!is_first);
-  GPR_ASSERT(!is_last);
+  GPR_ASSERT(!args->is_last);
   GPR_ASSERT(auth_context != NULL);
   GPR_ASSERT(creds != NULL);
 
@@ -258,7 +246,6 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
   chand->auth_context =
       GRPC_AUTH_CONTEXT_REF(auth_context, "server_auth_filter");
   chand->creds = grpc_server_credentials_ref(creds);
-  chand->mdctx = mdctx;
 }
 
 /* Destructor for channel data */
@@ -272,6 +259,6 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
 
 const grpc_channel_filter grpc_server_auth_filter = {
     auth_start_transport_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem,          destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,       destroy_channel_elem, grpc_call_next_get_peer,
+    init_call_elem, set_pollset, destroy_call_elem, sizeof(channel_data),
+    init_channel_elem, destroy_channel_elem, grpc_call_next_get_peer,
     "server-auth"};

src/core/security/server_secure_chttp2.c

@@ -87,20 +87,19 @@ static void state_unref(grpc_server_secure_state *state) {
 }
 
 static void setup_transport(grpc_exec_ctx *exec_ctx, void *statep,
-                            grpc_transport *transport, grpc_mdctx *mdctx) {
+                            grpc_transport *transport) {
   static grpc_channel_filter const *extra_filters[] = {
       &grpc_server_auth_filter, &grpc_http_server_filter};
   grpc_server_secure_state *state = statep;
   grpc_channel_args *args_copy;
   grpc_arg args_to_add[2];
   args_to_add[0] = grpc_server_credentials_to_arg(state->creds);
-  args_to_add[1] =
-      grpc_auth_context_to_arg(state->sc->auth_context);
+  args_to_add[1] = grpc_auth_context_to_arg(state->sc->auth_context);
   args_copy = grpc_channel_args_copy_and_add(
       grpc_server_get_channel_args(state->server), args_to_add,
       GPR_ARRAY_SIZE(args_to_add));
   grpc_server_setup_transport(exec_ctx, state->server, transport, extra_filters,
-                              GPR_ARRAY_SIZE(extra_filters), mdctx, args_copy);
+                              GPR_ARRAY_SIZE(extra_filters), args_copy);
   grpc_channel_args_destroy(args_copy);
 }
 
@@ -131,16 +130,14 @@ static void on_secure_handshake_done(grpc_exec_ctx *exec_ctx, void *statep,
                                      grpc_endpoint *secure_endpoint) {
   grpc_server_secure_state *state = statep;
   grpc_transport *transport;
-  grpc_mdctx *mdctx;
   if (status == GRPC_SECURITY_OK) {
     gpr_mu_lock(&state->mu);
     remove_tcp_from_list_locked(state, wrapped_endpoint);
     if (!state->is_shutdown) {
-      mdctx = grpc_mdctx_create();
       transport = grpc_create_chttp2_transport(
           exec_ctx, grpc_server_get_channel_args(state->server),
-          secure_endpoint, mdctx, 0);
-      setup_transport(exec_ctx, state, transport, mdctx);
+          secure_endpoint, 0);
+      setup_transport(exec_ctx, state, transport);
       grpc_chttp2_transport_start_reading(exec_ctx, transport, NULL, 0);
     } else {
       /* We need to consume this here, because the server may already have gone
@@ -237,6 +234,7 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
             creds->type);
     goto error;
   }
+  sc->channel_args = grpc_server_get_channel_args(server);
 
   /* resolve address */
   resolved = grpc_blocking_resolve_address(addr, "https");
@@ -250,9 +248,11 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
   }
 
   for (i = 0; i < resolved->naddrs; i++) {
-    port_temp = grpc_tcp_server_add_port(
+    grpc_tcp_listener *listener;
+    listener = grpc_tcp_server_add_port(
         tcp, (struct sockaddr *)&resolved->addrs[i].addr,
         resolved->addrs[i].len);
+    port_temp = grpc_tcp_listener_get_port(listener);
     if (port_temp >= 0) {
       if (port_num == -1) {
         port_num = port_temp;

src/core/support/avl.c

@@ -0,0 +1,288 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <grpc/support/avl.h>
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+
+gpr_avl gpr_avl_create(const gpr_avl_vtable *vtable) {
+  gpr_avl out;
+  out.vtable = vtable;
+  out.root = NULL;
+  return out;
+}
+
+static gpr_avl_node *ref_node(gpr_avl_node *node) {
+  if (node) {
+    gpr_ref(&node->refs);
+  }
+  return node;
+}
+
+static void unref_node(const gpr_avl_vtable *vtable, gpr_avl_node *node) {
+  if (node == NULL) {
+    return;
+  }
+  if (gpr_unref(&node->refs)) {
+    vtable->destroy_key(node->key);
+    vtable->destroy_value(node->value);
+    unref_node(vtable, node->left);
+    unref_node(vtable, node->right);
+    gpr_free(node);
+  }
+}
+
+static long node_height(gpr_avl_node *node) {
+  return node == NULL ? 0 : node->height;
+}
+
+#ifndef NDEBUG
+static long calculate_height(gpr_avl_node *node) {
+  return node == NULL ? 0 : 1 + GPR_MAX(calculate_height(node->left),
+                                        calculate_height(node->right));
+}
+
+static gpr_avl_node *assert_invariants(gpr_avl_node *n) {
+  if (n == NULL) return NULL;
+  assert_invariants(n->left);
+  assert_invariants(n->right);
+  assert(calculate_height(n) == n->height);
+  assert(labs(node_height(n->left) - node_height(n->right)) <= 1);
+  return n;
+}
+#else
+static gpr_avl_node *assert_invariants(gpr_avl_node *n) { return n; }
+#endif
+
+gpr_avl_node *new_node(void *key, void *value, gpr_avl_node *left,
+                       gpr_avl_node *right) {
+  gpr_avl_node *node = gpr_malloc(sizeof(*node));
+  gpr_ref_init(&node->refs, 1);
+  node->key = key;
+  node->value = value;
+  node->left = assert_invariants(left);
+  node->right = assert_invariants(right);
+  node->height = 1 + GPR_MAX(node_height(left), node_height(right));
+  return node;
+}
+
+static gpr_avl_node *get(const gpr_avl_vtable *vtable, gpr_avl_node *node,
+                         void *key) {
+  long cmp;
+
+  if (node == NULL) {
+    return NULL;
+  }
+
+  cmp = vtable->compare_keys(node->key, key);
+  if (cmp == 0) {
+    return node;
+  } else if (cmp > 0) {
+    return get(vtable, node->left, key);
+  } else {
+    return get(vtable, node->right, key);
+  }
+}
+
+void *gpr_avl_get(gpr_avl avl, void *key) {
+  gpr_avl_node *node = get(avl.vtable, avl.root, key);
+  return node ? node->value : NULL;
+}
+
+static gpr_avl_node *rotate_left(const gpr_avl_vtable *vtable, void *key,
+                                 void *value, gpr_avl_node *left,
+                                 gpr_avl_node *right) {
+  gpr_avl_node *n =
+      new_node(vtable->copy_key(right->key), vtable->copy_value(right->value),
+               new_node(key, value, left, ref_node(right->left)),
+               ref_node(right->right));
+  unref_node(vtable, right);
+  return n;
+}
+
+static gpr_avl_node *rotate_right(const gpr_avl_vtable *vtable, void *key,
+                                  void *value, gpr_avl_node *left,
+                                  gpr_avl_node *right) {
+  gpr_avl_node *n = new_node(
+      vtable->copy_key(left->key), vtable->copy_value(left->value),
+      ref_node(left->left), new_node(key, value, ref_node(left->right), right));
+  unref_node(vtable, left);
+  return n;
+}
+
+static gpr_avl_node *rotate_left_right(const gpr_avl_vtable *vtable, void *key,
+                                       void *value, gpr_avl_node *left,
+                                       gpr_avl_node *right) {
+  /* rotate_right(..., rotate_left(left), right) */
+  gpr_avl_node *n = new_node(
+      vtable->copy_key(left->right->key),
+      vtable->copy_value(left->right->value),
+      new_node(vtable->copy_key(left->key), vtable->copy_value(left->value),
+               ref_node(left->left), ref_node(left->right->left)),
+      new_node(key, value, ref_node(left->right->right), right));
+  unref_node(vtable, left);
+  return n;
+}
+
+static gpr_avl_node *rotate_right_left(const gpr_avl_vtable *vtable, void *key,
+                                       void *value, gpr_avl_node *left,
+                                       gpr_avl_node *right) {
+  /* rotate_left(..., left, rotate_right(right)) */
+  gpr_avl_node *n = new_node(
+      vtable->copy_key(right->left->key),
+      vtable->copy_value(right->left->value),
+      new_node(key, value, left, ref_node(right->left->left)),
+      new_node(vtable->copy_key(right->key), vtable->copy_key(right->value),
+               ref_node(right->left->right), ref_node(right->right)));
+  unref_node(vtable, right);
+  return n;
+}
+
+static gpr_avl_node *rebalance(const gpr_avl_vtable *vtable, void *key,
+                               void *value, gpr_avl_node *left,
+                               gpr_avl_node *right) {
+  switch (node_height(left) - node_height(right)) {
+    case 2:
+      if (node_height(left->left) - node_height(left->right) == -1) {
+        return assert_invariants(
+            rotate_left_right(vtable, key, value, left, right));
+      } else {
+        return assert_invariants(rotate_right(vtable, key, value, left, right));
+      }
+    case -2:
+      if (node_height(right->left) - node_height(right->right) == 1) {
+        return assert_invariants(
+            rotate_right_left(vtable, key, value, left, right));
+      } else {
+        return assert_invariants(rotate_left(vtable, key, value, left, right));
+      }
+    default:
+      return assert_invariants(new_node(key, value, left, right));
+  }
+}
+
+static gpr_avl_node *add(const gpr_avl_vtable *vtable, gpr_avl_node *node,
+                         void *key, void *value) {
+  long cmp;
+  if (node == NULL) {
+    return new_node(key, value, NULL, NULL);
+  }
+  cmp = vtable->compare_keys(node->key, key);
+  if (cmp == 0) {
+    return new_node(key, value, ref_node(node->left), ref_node(node->right));
+  } else if (cmp > 0) {
+    return rebalance(
+        vtable, vtable->copy_key(node->key), vtable->copy_value(node->value),
+        add(vtable, node->left, key, value), ref_node(node->right));
+  } else {
+    return rebalance(vtable, vtable->copy_key(node->key),
+                     vtable->copy_value(node->value), ref_node(node->left),
+                     add(vtable, node->right, key, value));
+  }
+}
+
+gpr_avl gpr_avl_add(gpr_avl avl, void *key, void *value) {
+  gpr_avl_node *old_root = avl.root;
+  avl.root = add(avl.vtable, avl.root, key, value);
+  assert_invariants(avl.root);
+  unref_node(avl.vtable, old_root);
+  return avl;
+}
+
+static gpr_avl_node *in_order_head(gpr_avl_node *node) {
+  while (node->left != NULL) {
+    node = node->left;
+  }
+  return node;
+}
+
+static gpr_avl_node *in_order_tail(gpr_avl_node *node) {
+  while (node->right != NULL) {
+    node = node->right;
+  }
+  return node;
+}
+
+static gpr_avl_node *remove(const gpr_avl_vtable *vtable, gpr_avl_node *node,
+                            void *key) {
+  long cmp;
+  if (node == NULL) {
+    return NULL;
+  }
+  cmp = vtable->compare_keys(node->key, key);
+  if (cmp == 0) {
+    if (node->left == NULL) {
+      return ref_node(node->right);
+    } else if (node->right == NULL) {
+      return ref_node(node->left);
+    } else if (node->left->height < node->right->height) {
+      gpr_avl_node *h = in_order_head(node->right);
+      return rebalance(vtable, vtable->copy_key(h->key),
+                       vtable->copy_value(h->value), ref_node(node->left),
+                       remove(vtable, node->right, h->key));
+    } else {
+      gpr_avl_node *h = in_order_tail(node->left);
+      return rebalance(
+          vtable, vtable->copy_key(h->key), vtable->copy_value(h->value),
+          remove(vtable, node->left, h->key), ref_node(node->right));
+    }
+  } else if (cmp > 0) {
+    return rebalance(vtable, vtable->copy_key(node->key),
+                     vtable->copy_value(node->value),
+                     remove(vtable, node->left, key), ref_node(node->right));
+  } else {
+    return rebalance(vtable, vtable->copy_key(node->key),
+                     vtable->copy_value(node->value), ref_node(node->left),
+                     remove(vtable, node->right, key));
+  }
+}
+
+gpr_avl gpr_avl_remove(gpr_avl avl, void *key) {
+  gpr_avl_node *old_root = avl.root;
+  avl.root = remove(avl.vtable, avl.root, key);
+  assert_invariants(avl.root);
+  unref_node(avl.vtable, old_root);
+  return avl;
+}
+
+gpr_avl gpr_avl_ref(gpr_avl avl) {
+  ref_node(avl.root);
+  return avl;
+}
+
+void gpr_avl_unref(gpr_avl avl) { unref_node(avl.vtable, avl.root); }

src/core/support/histogram.c

@@ -125,7 +125,7 @@ void gpr_histogram_add(gpr_histogram *h, double x) {
   h->buckets[bucket_for(h, x)]++;
 }
 
-int gpr_histogram_merge(gpr_histogram *dst, gpr_histogram *src) {
+int gpr_histogram_merge(gpr_histogram *dst, const gpr_histogram *src) {
   if ((dst->num_buckets != src->num_buckets) ||
       (dst->multiplier != src->multiplier)) {
     /* Fail because these histograms don't match */