Merge branch 'direct-calls' into zefuzz-dc

BUILD

@@ -51,6 +51,7 @@ cc_library(
     "src/core/lib/support/backoff.h",
     "src/core/lib/support/block_annotate.h",
     "src/core/lib/support/env.h",
+    "src/core/lib/support/mpscq.h",
     "src/core/lib/support/murmur_hash.h",
     "src/core/lib/support/percent_encoding.h",
     "src/core/lib/support/stack_lockfree.h",
@@ -79,6 +80,7 @@ cc_library(
     "src/core/lib/support/log_linux.c",
     "src/core/lib/support/log_posix.c",
     "src/core/lib/support/log_windows.c",
+    "src/core/lib/support/mpscq.c",
     "src/core/lib/support/murmur_hash.c",
     "src/core/lib/support/percent_encoding.c",
     "src/core/lib/support/slice.c",
@@ -169,6 +171,7 @@ cc_library(
     "src/core/lib/channel/handshaker.h",
     "src/core/lib/channel/http_client_filter.h",
     "src/core/lib/channel/http_server_filter.h",
+    "src/core/lib/channel/message_size_filter.h",
     "src/core/lib/compression/algorithm_metadata.h",
     "src/core/lib/compression/message_compress.h",
     "src/core/lib/debug/trace.h",
@@ -176,6 +179,7 @@ cc_library(
     "src/core/lib/http/httpcli.h",
     "src/core/lib/http/parser.h",
     "src/core/lib/iomgr/closure.h",
+    "src/core/lib/iomgr/combiner.h",
     "src/core/lib/iomgr/endpoint.h",
     "src/core/lib/iomgr/endpoint_pair.h",
     "src/core/lib/iomgr/error.h",
@@ -215,7 +219,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_pipe.h",
     "src/core/lib/iomgr/wakeup_fd_posix.h",
     "src/core/lib/iomgr/workqueue.h",
-    "src/core/lib/iomgr/workqueue_posix.h",
     "src/core/lib/iomgr/workqueue_windows.h",
     "src/core/lib/json/json.h",
     "src/core/lib/json/json_common.h",
@@ -315,6 +318,7 @@ cc_library(
     "src/core/ext/census/mlog.h",
     "src/core/ext/census/resource.h",
     "src/core/ext/census/rpc_metric_id.h",
+    "src/core/ext/census/trace_context.h",
     "src/core/lib/surface/init.c",
     "src/core/lib/channel/channel_args.c",
     "src/core/lib/channel/channel_stack.c",
@@ -324,6 +328,7 @@ cc_library(
     "src/core/lib/channel/handshaker.c",
     "src/core/lib/channel/http_client_filter.c",
     "src/core/lib/channel/http_server_filter.c",
+    "src/core/lib/channel/message_size_filter.c",
     "src/core/lib/compression/compression.c",
     "src/core/lib/compression/message_compress.c",
     "src/core/lib/debug/trace.c",
@@ -331,6 +336,7 @@ cc_library(
     "src/core/lib/http/httpcli.c",
     "src/core/lib/http/parser.c",
     "src/core/lib/iomgr/closure.c",
+    "src/core/lib/iomgr/combiner.c",
     "src/core/lib/iomgr/endpoint.c",
     "src/core/lib/iomgr/endpoint_pair_posix.c",
     "src/core/lib/iomgr/endpoint_pair_windows.c",
@@ -373,7 +379,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_nospecial.c",
     "src/core/lib/iomgr/wakeup_fd_pipe.c",
     "src/core/lib/iomgr/wakeup_fd_posix.c",
-    "src/core/lib/iomgr/workqueue_posix.c",
     "src/core/lib/iomgr/workqueue_windows.c",
     "src/core/lib/json/json.c",
     "src/core/lib/json/json_reader.c",
@@ -500,6 +505,7 @@ cc_library(
     "src/core/ext/census/operation.c",
     "src/core/ext/census/placeholders.c",
     "src/core/ext/census/resource.c",
+    "src/core/ext/census/trace_context.c",
     "src/core/ext/census/tracing.c",
     "src/core/plugin_registry/grpc_plugin_registry.c",
   ],
@@ -560,6 +566,7 @@ cc_library(
     "src/core/lib/channel/handshaker.h",
     "src/core/lib/channel/http_client_filter.h",
     "src/core/lib/channel/http_server_filter.h",
+    "src/core/lib/channel/message_size_filter.h",
     "src/core/lib/compression/algorithm_metadata.h",
     "src/core/lib/compression/message_compress.h",
     "src/core/lib/debug/trace.h",
@@ -567,6 +574,7 @@ cc_library(
     "src/core/lib/http/httpcli.h",
     "src/core/lib/http/parser.h",
     "src/core/lib/iomgr/closure.h",
+    "src/core/lib/iomgr/combiner.h",
     "src/core/lib/iomgr/endpoint.h",
     "src/core/lib/iomgr/endpoint_pair.h",
     "src/core/lib/iomgr/error.h",
@@ -606,7 +614,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_pipe.h",
     "src/core/lib/iomgr/wakeup_fd_posix.h",
     "src/core/lib/iomgr/workqueue.h",
-    "src/core/lib/iomgr/workqueue_posix.h",
     "src/core/lib/iomgr/workqueue_windows.h",
     "src/core/lib/json/json.h",
     "src/core/lib/json/json_common.h",
@@ -701,6 +708,7 @@ cc_library(
     "src/core/lib/channel/handshaker.c",
     "src/core/lib/channel/http_client_filter.c",
     "src/core/lib/channel/http_server_filter.c",
+    "src/core/lib/channel/message_size_filter.c",
     "src/core/lib/compression/compression.c",
     "src/core/lib/compression/message_compress.c",
     "src/core/lib/debug/trace.c",
@@ -708,6 +716,7 @@ cc_library(
     "src/core/lib/http/httpcli.c",
     "src/core/lib/http/parser.c",
     "src/core/lib/iomgr/closure.c",
+    "src/core/lib/iomgr/combiner.c",
     "src/core/lib/iomgr/endpoint.c",
     "src/core/lib/iomgr/endpoint_pair_posix.c",
     "src/core/lib/iomgr/endpoint_pair_windows.c",
@@ -750,7 +759,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_nospecial.c",
     "src/core/lib/iomgr/wakeup_fd_pipe.c",
     "src/core/lib/iomgr/wakeup_fd_posix.c",
-    "src/core/lib/iomgr/workqueue_posix.c",
     "src/core/lib/iomgr/workqueue_windows.c",
     "src/core/lib/json/json.c",
     "src/core/lib/json/json_reader.c",
@@ -908,6 +916,7 @@ cc_library(
     "src/core/lib/channel/handshaker.h",
     "src/core/lib/channel/http_client_filter.h",
     "src/core/lib/channel/http_server_filter.h",
+    "src/core/lib/channel/message_size_filter.h",
     "src/core/lib/compression/algorithm_metadata.h",
     "src/core/lib/compression/message_compress.h",
     "src/core/lib/debug/trace.h",
@@ -915,6 +924,7 @@ cc_library(
     "src/core/lib/http/httpcli.h",
     "src/core/lib/http/parser.h",
     "src/core/lib/iomgr/closure.h",
+    "src/core/lib/iomgr/combiner.h",
     "src/core/lib/iomgr/endpoint.h",
     "src/core/lib/iomgr/endpoint_pair.h",
     "src/core/lib/iomgr/error.h",
@@ -954,7 +964,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_pipe.h",
     "src/core/lib/iomgr/wakeup_fd_posix.h",
     "src/core/lib/iomgr/workqueue.h",
-    "src/core/lib/iomgr/workqueue_posix.h",
     "src/core/lib/iomgr/workqueue_windows.h",
     "src/core/lib/json/json.h",
     "src/core/lib/json/json_common.h",
@@ -1030,6 +1039,7 @@ cc_library(
     "src/core/ext/census/mlog.h",
     "src/core/ext/census/resource.h",
     "src/core/ext/census/rpc_metric_id.h",
+    "src/core/ext/census/trace_context.h",
     "src/core/lib/surface/init.c",
     "src/core/lib/surface/init_unsecure.c",
     "src/core/lib/channel/channel_args.c",
@@ -1040,6 +1050,7 @@ cc_library(
     "src/core/lib/channel/handshaker.c",
     "src/core/lib/channel/http_client_filter.c",
     "src/core/lib/channel/http_server_filter.c",
+    "src/core/lib/channel/message_size_filter.c",
     "src/core/lib/compression/compression.c",
     "src/core/lib/compression/message_compress.c",
     "src/core/lib/debug/trace.c",
@@ -1047,6 +1058,7 @@ cc_library(
     "src/core/lib/http/httpcli.c",
     "src/core/lib/http/parser.c",
     "src/core/lib/iomgr/closure.c",
+    "src/core/lib/iomgr/combiner.c",
     "src/core/lib/iomgr/endpoint.c",
     "src/core/lib/iomgr/endpoint_pair_posix.c",
     "src/core/lib/iomgr/endpoint_pair_windows.c",
@@ -1089,7 +1101,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_nospecial.c",
     "src/core/lib/iomgr/wakeup_fd_pipe.c",
     "src/core/lib/iomgr/wakeup_fd_posix.c",
-    "src/core/lib/iomgr/workqueue_posix.c",
     "src/core/lib/iomgr/workqueue_windows.c",
     "src/core/lib/json/json.c",
     "src/core/lib/json/json_reader.c",
@@ -1186,6 +1197,7 @@ cc_library(
     "src/core/ext/census/operation.c",
     "src/core/ext/census/placeholders.c",
     "src/core/ext/census/resource.c",
+    "src/core/ext/census/trace_context.c",
     "src/core/ext/census/tracing.c",
     "src/core/plugin_registry/grpc_unsecure_plugin_registry.c",
   ],
@@ -1251,6 +1263,7 @@ cc_library(
     "src/core/lib/channel/handshaker.h",
     "src/core/lib/channel/http_client_filter.h",
     "src/core/lib/channel/http_server_filter.h",
+    "src/core/lib/channel/message_size_filter.h",
     "src/core/lib/compression/algorithm_metadata.h",
     "src/core/lib/compression/message_compress.h",
     "src/core/lib/debug/trace.h",
@@ -1258,6 +1271,7 @@ cc_library(
     "src/core/lib/http/httpcli.h",
     "src/core/lib/http/parser.h",
     "src/core/lib/iomgr/closure.h",
+    "src/core/lib/iomgr/combiner.h",
     "src/core/lib/iomgr/endpoint.h",
     "src/core/lib/iomgr/endpoint_pair.h",
     "src/core/lib/iomgr/error.h",
@@ -1297,7 +1311,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_pipe.h",
     "src/core/lib/iomgr/wakeup_fd_posix.h",
     "src/core/lib/iomgr/workqueue.h",
-    "src/core/lib/iomgr/workqueue_posix.h",
     "src/core/lib/iomgr/workqueue_windows.h",
     "src/core/lib/json/json.h",
     "src/core/lib/json/json_common.h",
@@ -1363,6 +1376,7 @@ cc_library(
     "src/core/lib/channel/handshaker.c",
     "src/core/lib/channel/http_client_filter.c",
     "src/core/lib/channel/http_server_filter.c",
+    "src/core/lib/channel/message_size_filter.c",
     "src/core/lib/compression/compression.c",
     "src/core/lib/compression/message_compress.c",
     "src/core/lib/debug/trace.c",
@@ -1370,6 +1384,7 @@ cc_library(
     "src/core/lib/http/httpcli.c",
     "src/core/lib/http/parser.c",
     "src/core/lib/iomgr/closure.c",
+    "src/core/lib/iomgr/combiner.c",
     "src/core/lib/iomgr/endpoint.c",
     "src/core/lib/iomgr/endpoint_pair_posix.c",
     "src/core/lib/iomgr/endpoint_pair_windows.c",
@@ -1412,7 +1427,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_nospecial.c",
     "src/core/lib/iomgr/wakeup_fd_pipe.c",
     "src/core/lib/iomgr/wakeup_fd_posix.c",
-    "src/core/lib/iomgr/workqueue_posix.c",
     "src/core/lib/iomgr/workqueue_windows.c",
     "src/core/lib/json/json.c",
     "src/core/lib/json/json_reader.c",
@@ -1541,6 +1555,7 @@ cc_library(
     "include/grpc++/impl/codegen/service_type.h",
     "include/grpc++/impl/codegen/status.h",
     "include/grpc++/impl/codegen/status_code_enum.h",
+    "include/grpc++/impl/codegen/status_helper.h",
     "include/grpc++/impl/codegen/string_ref.h",
     "include/grpc++/impl/codegen/stub_options.h",
     "include/grpc++/impl/codegen/sync.h",
@@ -1600,6 +1615,7 @@ cc_library(
     "include/grpc++/impl/codegen/service_type.h",
     "include/grpc++/impl/codegen/status.h",
     "include/grpc++/impl/codegen/status_code_enum.h",
+    "include/grpc++/impl/codegen/status_helper.h",
     "include/grpc++/impl/codegen/string_ref.h",
     "include/grpc++/impl/codegen/stub_options.h",
     "include/grpc++/impl/codegen/sync.h",
@@ -1653,6 +1669,7 @@ cc_library(
     "src/core/lib/channel/handshaker.h",
     "src/core/lib/channel/http_client_filter.h",
     "src/core/lib/channel/http_server_filter.h",
+    "src/core/lib/channel/message_size_filter.h",
     "src/core/lib/compression/algorithm_metadata.h",
     "src/core/lib/compression/message_compress.h",
     "src/core/lib/debug/trace.h",
@@ -1660,6 +1677,7 @@ cc_library(
     "src/core/lib/http/httpcli.h",
     "src/core/lib/http/parser.h",
     "src/core/lib/iomgr/closure.h",
+    "src/core/lib/iomgr/combiner.h",
     "src/core/lib/iomgr/endpoint.h",
     "src/core/lib/iomgr/endpoint_pair.h",
     "src/core/lib/iomgr/error.h",
@@ -1699,7 +1717,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_pipe.h",
     "src/core/lib/iomgr/wakeup_fd_posix.h",
     "src/core/lib/iomgr/workqueue.h",
-    "src/core/lib/iomgr/workqueue_posix.h",
     "src/core/lib/iomgr/workqueue_windows.h",
     "src/core/lib/json/json.h",
     "src/core/lib/json/json_common.h",
@@ -1760,6 +1777,7 @@ cc_library(
     "src/core/lib/channel/handshaker.c",
     "src/core/lib/channel/http_client_filter.c",
     "src/core/lib/channel/http_server_filter.c",
+    "src/core/lib/channel/message_size_filter.c",
     "src/core/lib/compression/compression.c",
     "src/core/lib/compression/message_compress.c",
     "src/core/lib/debug/trace.c",
@@ -1767,6 +1785,7 @@ cc_library(
     "src/core/lib/http/httpcli.c",
     "src/core/lib/http/parser.c",
     "src/core/lib/iomgr/closure.c",
+    "src/core/lib/iomgr/combiner.c",
     "src/core/lib/iomgr/endpoint.c",
     "src/core/lib/iomgr/endpoint_pair_posix.c",
     "src/core/lib/iomgr/endpoint_pair_windows.c",
@@ -1809,7 +1828,6 @@ cc_library(
     "src/core/lib/iomgr/wakeup_fd_nospecial.c",
     "src/core/lib/iomgr/wakeup_fd_pipe.c",
     "src/core/lib/iomgr/wakeup_fd_posix.c",
-    "src/core/lib/iomgr/workqueue_posix.c",
     "src/core/lib/iomgr/workqueue_windows.c",
     "src/core/lib/json/json.c",
     "src/core/lib/json/json_reader.c",
@@ -1938,6 +1956,7 @@ cc_library(
     "include/grpc++/impl/codegen/service_type.h",
     "include/grpc++/impl/codegen/status.h",
     "include/grpc++/impl/codegen/status_code_enum.h",
+    "include/grpc++/impl/codegen/status_helper.h",
     "include/grpc++/impl/codegen/string_ref.h",
     "include/grpc++/impl/codegen/stub_options.h",
     "include/grpc++/impl/codegen/sync.h",
@@ -2041,6 +2060,7 @@ objc_library(
     "src/core/lib/support/log_linux.c",
     "src/core/lib/support/log_posix.c",
     "src/core/lib/support/log_windows.c",
+    "src/core/lib/support/mpscq.c",
     "src/core/lib/support/murmur_hash.c",
     "src/core/lib/support/percent_encoding.c",
     "src/core/lib/support/slice.c",
@@ -2112,6 +2132,7 @@ objc_library(
     "src/core/lib/support/backoff.h",
     "src/core/lib/support/block_annotate.h",
     "src/core/lib/support/env.h",
+    "src/core/lib/support/mpscq.h",
     "src/core/lib/support/murmur_hash.h",
     "src/core/lib/support/percent_encoding.h",
     "src/core/lib/support/stack_lockfree.h",
@@ -2143,6 +2164,7 @@ objc_library(
     "src/core/lib/channel/handshaker.c",
     "src/core/lib/channel/http_client_filter.c",
     "src/core/lib/channel/http_server_filter.c",
+    "src/core/lib/channel/message_size_filter.c",
     "src/core/lib/compression/compression.c",
     "src/core/lib/compression/message_compress.c",
     "src/core/lib/debug/trace.c",
@@ -2150,6 +2172,7 @@ objc_library(
     "src/core/lib/http/httpcli.c",
     "src/core/lib/http/parser.c",
     "src/core/lib/iomgr/closure.c",
+    "src/core/lib/iomgr/combiner.c",
     "src/core/lib/iomgr/endpoint.c",
     "src/core/lib/iomgr/endpoint_pair_posix.c",
     "src/core/lib/iomgr/endpoint_pair_windows.c",
@@ -2192,7 +2215,6 @@ objc_library(
     "src/core/lib/iomgr/wakeup_fd_nospecial.c",
     "src/core/lib/iomgr/wakeup_fd_pipe.c",
     "src/core/lib/iomgr/wakeup_fd_posix.c",
-    "src/core/lib/iomgr/workqueue_posix.c",
     "src/core/lib/iomgr/workqueue_windows.c",
     "src/core/lib/json/json.c",
     "src/core/lib/json/json_reader.c",
@@ -2319,6 +2341,7 @@ objc_library(
     "src/core/ext/census/operation.c",
     "src/core/ext/census/placeholders.c",
     "src/core/ext/census/resource.c",
+    "src/core/ext/census/trace_context.c",
     "src/core/ext/census/tracing.c",
     "src/core/plugin_registry/grpc_plugin_registry.c",
   ],
@@ -2358,6 +2381,7 @@ objc_library(
     "src/core/lib/channel/handshaker.h",
     "src/core/lib/channel/http_client_filter.h",
     "src/core/lib/channel/http_server_filter.h",
+    "src/core/lib/channel/message_size_filter.h",
     "src/core/lib/compression/algorithm_metadata.h",
     "src/core/lib/compression/message_compress.h",
     "src/core/lib/debug/trace.h",
@@ -2365,6 +2389,7 @@ objc_library(
     "src/core/lib/http/httpcli.h",
     "src/core/lib/http/parser.h",
     "src/core/lib/iomgr/closure.h",
+    "src/core/lib/iomgr/combiner.h",
     "src/core/lib/iomgr/endpoint.h",
     "src/core/lib/iomgr/endpoint_pair.h",
     "src/core/lib/iomgr/error.h",
@@ -2404,7 +2429,6 @@ objc_library(
     "src/core/lib/iomgr/wakeup_fd_pipe.h",
     "src/core/lib/iomgr/wakeup_fd_posix.h",
     "src/core/lib/iomgr/workqueue.h",
-    "src/core/lib/iomgr/workqueue_posix.h",
     "src/core/lib/iomgr/workqueue_windows.h",
     "src/core/lib/json/json.h",
     "src/core/lib/json/json_common.h",
@@ -2504,6 +2528,7 @@ objc_library(
     "src/core/ext/census/mlog.h",
     "src/core/ext/census/resource.h",
     "src/core/ext/census/rpc_metric_id.h",
+    "src/core/ext/census/trace_context.h",
   ],
   includes = [
     "include",

CMakeLists.txt

@@ -191,6 +191,7 @@ add_library(gpr
   src/core/lib/support/log_linux.c
   src/core/lib/support/log_posix.c
   src/core/lib/support/log_windows.c
+  src/core/lib/support/mpscq.c
   src/core/lib/support/murmur_hash.c
   src/core/lib/support/percent_encoding.c
   src/core/lib/support/slice.c
@@ -297,6 +298,7 @@ add_library(grpc
   src/core/lib/channel/handshaker.c
   src/core/lib/channel/http_client_filter.c
   src/core/lib/channel/http_server_filter.c
+  src/core/lib/channel/message_size_filter.c
   src/core/lib/compression/compression.c
   src/core/lib/compression/message_compress.c
   src/core/lib/debug/trace.c
@@ -304,6 +306,7 @@ add_library(grpc
   src/core/lib/http/httpcli.c
   src/core/lib/http/parser.c
   src/core/lib/iomgr/closure.c
+  src/core/lib/iomgr/combiner.c
   src/core/lib/iomgr/endpoint.c
   src/core/lib/iomgr/endpoint_pair_posix.c
   src/core/lib/iomgr/endpoint_pair_windows.c
@@ -346,7 +349,6 @@ add_library(grpc
   src/core/lib/iomgr/wakeup_fd_nospecial.c
   src/core/lib/iomgr/wakeup_fd_pipe.c
   src/core/lib/iomgr/wakeup_fd_posix.c
-  src/core/lib/iomgr/workqueue_posix.c
   src/core/lib/iomgr/workqueue_windows.c
   src/core/lib/json/json.c
   src/core/lib/json/json_reader.c
@@ -476,6 +478,7 @@ add_library(grpc
   src/core/ext/census/operation.c
   src/core/ext/census/placeholders.c
   src/core/ext/census/resource.c
+  src/core/ext/census/trace_context.c
   src/core/ext/census/tracing.c
   src/core/plugin_registry/grpc_plugin_registry.c
 )
@@ -551,6 +554,7 @@ add_library(grpc_cronet
   src/core/lib/channel/handshaker.c
   src/core/lib/channel/http_client_filter.c
   src/core/lib/channel/http_server_filter.c
+  src/core/lib/channel/message_size_filter.c
   src/core/lib/compression/compression.c
   src/core/lib/compression/message_compress.c
   src/core/lib/debug/trace.c
@@ -558,6 +562,7 @@ add_library(grpc_cronet
   src/core/lib/http/httpcli.c
   src/core/lib/http/parser.c
   src/core/lib/iomgr/closure.c
+  src/core/lib/iomgr/combiner.c
   src/core/lib/iomgr/endpoint.c
   src/core/lib/iomgr/endpoint_pair_posix.c
   src/core/lib/iomgr/endpoint_pair_windows.c
@@ -600,7 +605,6 @@ add_library(grpc_cronet
   src/core/lib/iomgr/wakeup_fd_nospecial.c
   src/core/lib/iomgr/wakeup_fd_pipe.c
   src/core/lib/iomgr/wakeup_fd_posix.c
-  src/core/lib/iomgr/workqueue_posix.c
   src/core/lib/iomgr/workqueue_windows.c
   src/core/lib/json/json.c
   src/core/lib/json/json_reader.c
@@ -778,6 +782,7 @@ add_library(grpc_unsecure
   src/core/lib/channel/handshaker.c
   src/core/lib/channel/http_client_filter.c
   src/core/lib/channel/http_server_filter.c
+  src/core/lib/channel/message_size_filter.c
   src/core/lib/compression/compression.c
   src/core/lib/compression/message_compress.c
   src/core/lib/debug/trace.c
@@ -785,6 +790,7 @@ add_library(grpc_unsecure
   src/core/lib/http/httpcli.c
   src/core/lib/http/parser.c
   src/core/lib/iomgr/closure.c
+  src/core/lib/iomgr/combiner.c
   src/core/lib/iomgr/endpoint.c
   src/core/lib/iomgr/endpoint_pair_posix.c
   src/core/lib/iomgr/endpoint_pair_windows.c
@@ -827,7 +833,6 @@ add_library(grpc_unsecure
   src/core/lib/iomgr/wakeup_fd_nospecial.c
   src/core/lib/iomgr/wakeup_fd_pipe.c
   src/core/lib/iomgr/wakeup_fd_posix.c
-  src/core/lib/iomgr/workqueue_posix.c
   src/core/lib/iomgr/workqueue_windows.c
   src/core/lib/json/json.c
   src/core/lib/json/json_reader.c
@@ -927,6 +932,7 @@ add_library(grpc_unsecure
   src/core/ext/census/operation.c
   src/core/ext/census/placeholders.c
   src/core/ext/census/resource.c
+  src/core/ext/census/trace_context.c
   src/core/ext/census/tracing.c
   src/core/plugin_registry/grpc_unsecure_plugin_registry.c
 )
@@ -1031,6 +1037,7 @@ add_library(grpc++
   src/core/lib/channel/handshaker.c
   src/core/lib/channel/http_client_filter.c
   src/core/lib/channel/http_server_filter.c
+  src/core/lib/channel/message_size_filter.c
   src/core/lib/compression/compression.c
   src/core/lib/compression/message_compress.c
   src/core/lib/debug/trace.c
@@ -1038,6 +1045,7 @@ add_library(grpc++
   src/core/lib/http/httpcli.c
   src/core/lib/http/parser.c
   src/core/lib/iomgr/closure.c
+  src/core/lib/iomgr/combiner.c
   src/core/lib/iomgr/endpoint.c
   src/core/lib/iomgr/endpoint_pair_posix.c
   src/core/lib/iomgr/endpoint_pair_windows.c
@@ -1080,7 +1088,6 @@ add_library(grpc++
   src/core/lib/iomgr/wakeup_fd_nospecial.c
   src/core/lib/iomgr/wakeup_fd_pipe.c
   src/core/lib/iomgr/wakeup_fd_posix.c
-  src/core/lib/iomgr/workqueue_posix.c
   src/core/lib/iomgr/workqueue_windows.c
   src/core/lib/json/json.c
   src/core/lib/json/json_reader.c
@@ -1227,6 +1234,7 @@ foreach(_hdr
   include/grpc++/impl/codegen/service_type.h
   include/grpc++/impl/codegen/status.h
   include/grpc++/impl/codegen/status_code_enum.h
+  include/grpc++/impl/codegen/status_helper.h
   include/grpc++/impl/codegen/string_ref.h
   include/grpc++/impl/codegen/stub_options.h
   include/grpc++/impl/codegen/sync.h
@@ -1300,6 +1308,7 @@ foreach(_hdr
   include/grpc++/impl/codegen/service_type.h
   include/grpc++/impl/codegen/status.h
   include/grpc++/impl/codegen/status_code_enum.h
+  include/grpc++/impl/codegen/status_helper.h
   include/grpc++/impl/codegen/string_ref.h
   include/grpc++/impl/codegen/stub_options.h
   include/grpc++/impl/codegen/sync.h
@@ -1380,6 +1389,7 @@ add_library(grpc++_unsecure
   src/core/lib/channel/handshaker.c
   src/core/lib/channel/http_client_filter.c
   src/core/lib/channel/http_server_filter.c
+  src/core/lib/channel/message_size_filter.c
   src/core/lib/compression/compression.c
   src/core/lib/compression/message_compress.c
   src/core/lib/debug/trace.c
@@ -1387,6 +1397,7 @@ add_library(grpc++_unsecure
   src/core/lib/http/httpcli.c
   src/core/lib/http/parser.c
   src/core/lib/iomgr/closure.c
+  src/core/lib/iomgr/combiner.c
   src/core/lib/iomgr/endpoint.c
   src/core/lib/iomgr/endpoint_pair_posix.c
   src/core/lib/iomgr/endpoint_pair_windows.c
@@ -1429,7 +1440,6 @@ add_library(grpc++_unsecure
   src/core/lib/iomgr/wakeup_fd_nospecial.c
   src/core/lib/iomgr/wakeup_fd_pipe.c
   src/core/lib/iomgr/wakeup_fd_posix.c
-  src/core/lib/iomgr/workqueue_posix.c
   src/core/lib/iomgr/workqueue_windows.c
   src/core/lib/json/json.c
   src/core/lib/json/json_reader.c
@@ -1575,6 +1585,7 @@ foreach(_hdr
   include/grpc++/impl/codegen/service_type.h
   include/grpc++/impl/codegen/status.h
   include/grpc++/impl/codegen/status_code_enum.h
+  include/grpc++/impl/codegen/status_helper.h
   include/grpc++/impl/codegen/string_ref.h
   include/grpc++/impl/codegen/stub_options.h
   include/grpc++/impl/codegen/sync.h

Makefile

@@ -909,12 +909,14 @@ bin_decoder_test: $(BINDIR)/$(CONFIG)/bin_decoder_test
 bin_encoder_test: $(BINDIR)/$(CONFIG)/bin_encoder_test
 census_context_test: $(BINDIR)/$(CONFIG)/census_context_test
 census_resource_test: $(BINDIR)/$(CONFIG)/census_resource_test
+census_trace_context_test: $(BINDIR)/$(CONFIG)/census_trace_context_test
 channel_create_test: $(BINDIR)/$(CONFIG)/channel_create_test
 chttp2_hpack_encoder_test: $(BINDIR)/$(CONFIG)/chttp2_hpack_encoder_test
 chttp2_status_conversion_test: $(BINDIR)/$(CONFIG)/chttp2_status_conversion_test
 chttp2_stream_map_test: $(BINDIR)/$(CONFIG)/chttp2_stream_map_test
 chttp2_varint_test: $(BINDIR)/$(CONFIG)/chttp2_varint_test
 client_fuzzer: $(BINDIR)/$(CONFIG)/client_fuzzer
+combiner_test: $(BINDIR)/$(CONFIG)/combiner_test
 compression_test: $(BINDIR)/$(CONFIG)/compression_test
 concurrent_connectivity_test: $(BINDIR)/$(CONFIG)/concurrent_connectivity_test
 dns_resolver_connectivity_test: $(BINDIR)/$(CONFIG)/dns_resolver_connectivity_test
@@ -940,6 +942,7 @@ gpr_env_test: $(BINDIR)/$(CONFIG)/gpr_env_test
 gpr_histogram_test: $(BINDIR)/$(CONFIG)/gpr_histogram_test
 gpr_host_port_test: $(BINDIR)/$(CONFIG)/gpr_host_port_test
 gpr_log_test: $(BINDIR)/$(CONFIG)/gpr_log_test
+gpr_mpscq_test: $(BINDIR)/$(CONFIG)/gpr_mpscq_test
 gpr_percent_encoding_test: $(BINDIR)/$(CONFIG)/gpr_percent_encoding_test
 gpr_slice_buffer_test: $(BINDIR)/$(CONFIG)/gpr_slice_buffer_test
 gpr_slice_test: $(BINDIR)/$(CONFIG)/gpr_slice_test
@@ -1235,11 +1238,13 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/bin_encoder_test \
   $(BINDIR)/$(CONFIG)/census_context_test \
   $(BINDIR)/$(CONFIG)/census_resource_test \
+  $(BINDIR)/$(CONFIG)/census_trace_context_test \
   $(BINDIR)/$(CONFIG)/channel_create_test \
   $(BINDIR)/$(CONFIG)/chttp2_hpack_encoder_test \
   $(BINDIR)/$(CONFIG)/chttp2_status_conversion_test \
   $(BINDIR)/$(CONFIG)/chttp2_stream_map_test \
   $(BINDIR)/$(CONFIG)/chttp2_varint_test \
+  $(BINDIR)/$(CONFIG)/combiner_test \
   $(BINDIR)/$(CONFIG)/compression_test \
   $(BINDIR)/$(CONFIG)/concurrent_connectivity_test \
   $(BINDIR)/$(CONFIG)/dns_resolver_connectivity_test \
@@ -1262,6 +1267,7 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/gpr_histogram_test \
   $(BINDIR)/$(CONFIG)/gpr_host_port_test \
   $(BINDIR)/$(CONFIG)/gpr_log_test \
+  $(BINDIR)/$(CONFIG)/gpr_mpscq_test \
   $(BINDIR)/$(CONFIG)/gpr_percent_encoding_test \
   $(BINDIR)/$(CONFIG)/gpr_slice_buffer_test \
   $(BINDIR)/$(CONFIG)/gpr_slice_test \
@@ -1547,6 +1553,8 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/census_context_test || ( echo test census_context_test failed ; exit 1 )
 	$(E) "[RUN]     Testing census_resource_test"
 	$(Q) $(BINDIR)/$(CONFIG)/census_resource_test || ( echo test census_resource_test failed ; exit 1 )
+	$(E) "[RUN]     Testing census_trace_context_test"
+	$(Q) $(BINDIR)/$(CONFIG)/census_trace_context_test || ( echo test census_trace_context_test failed ; exit 1 )
 	$(E) "[RUN]     Testing channel_create_test"
 	$(Q) $(BINDIR)/$(CONFIG)/channel_create_test || ( echo test channel_create_test failed ; exit 1 )
 	$(E) "[RUN]     Testing chttp2_hpack_encoder_test"
@@ -1557,6 +1565,8 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/chttp2_stream_map_test || ( echo test chttp2_stream_map_test failed ; exit 1 )
 	$(E) "[RUN]     Testing chttp2_varint_test"
 	$(Q) $(BINDIR)/$(CONFIG)/chttp2_varint_test || ( echo test chttp2_varint_test failed ; exit 1 )
+	$(E) "[RUN]     Testing combiner_test"
+	$(Q) $(BINDIR)/$(CONFIG)/combiner_test || ( echo test combiner_test failed ; exit 1 )
 	$(E) "[RUN]     Testing compression_test"
 	$(Q) $(BINDIR)/$(CONFIG)/compression_test || ( echo test compression_test failed ; exit 1 )
 	$(E) "[RUN]     Testing concurrent_connectivity_test"
@@ -1597,6 +1607,8 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/gpr_host_port_test || ( echo test gpr_host_port_test failed ; exit 1 )
 	$(E) "[RUN]     Testing gpr_log_test"
 	$(Q) $(BINDIR)/$(CONFIG)/gpr_log_test || ( echo test gpr_log_test failed ; exit 1 )
+	$(E) "[RUN]     Testing gpr_mpscq_test"
+	$(Q) $(BINDIR)/$(CONFIG)/gpr_mpscq_test || ( echo test gpr_mpscq_test failed ; exit 1 )
 	$(E) "[RUN]     Testing gpr_percent_encoding_test"
 	$(Q) $(BINDIR)/$(CONFIG)/gpr_percent_encoding_test || ( echo test gpr_percent_encoding_test failed ; exit 1 )
 	$(E) "[RUN]     Testing gpr_slice_buffer_test"
@@ -2378,6 +2390,7 @@ LIBGPR_SRC = \
     src/core/lib/support/log_linux.c \
     src/core/lib/support/log_posix.c \
     src/core/lib/support/log_windows.c \
+    src/core/lib/support/mpscq.c \
     src/core/lib/support/murmur_hash.c \
     src/core/lib/support/percent_encoding.c \
     src/core/lib/support/slice.c \
@@ -2518,6 +2531,7 @@ LIBGRPC_SRC = \
     src/core/lib/channel/handshaker.c \
     src/core/lib/channel/http_client_filter.c \
     src/core/lib/channel/http_server_filter.c \
+    src/core/lib/channel/message_size_filter.c \
     src/core/lib/compression/compression.c \
     src/core/lib/compression/message_compress.c \
     src/core/lib/debug/trace.c \
@@ -2525,6 +2539,7 @@ LIBGRPC_SRC = \
     src/core/lib/http/httpcli.c \
     src/core/lib/http/parser.c \
     src/core/lib/iomgr/closure.c \
+    src/core/lib/iomgr/combiner.c \
     src/core/lib/iomgr/endpoint.c \
     src/core/lib/iomgr/endpoint_pair_posix.c \
     src/core/lib/iomgr/endpoint_pair_windows.c \
@@ -2567,7 +2582,6 @@ LIBGRPC_SRC = \
     src/core/lib/iomgr/wakeup_fd_nospecial.c \
     src/core/lib/iomgr/wakeup_fd_pipe.c \
     src/core/lib/iomgr/wakeup_fd_posix.c \
-    src/core/lib/iomgr/workqueue_posix.c \
     src/core/lib/iomgr/workqueue_windows.c \
     src/core/lib/json/json.c \
     src/core/lib/json/json_reader.c \
@@ -2697,6 +2711,7 @@ LIBGRPC_SRC = \
     src/core/ext/census/operation.c \
     src/core/ext/census/placeholders.c \
     src/core/ext/census/resource.c \
+    src/core/ext/census/trace_context.c \
     src/core/ext/census/tracing.c \
     src/core/plugin_registry/grpc_plugin_registry.c \
 
@@ -2790,6 +2805,7 @@ LIBGRPC_CRONET_SRC = \
     src/core/lib/channel/handshaker.c \
     src/core/lib/channel/http_client_filter.c \
     src/core/lib/channel/http_server_filter.c \
+    src/core/lib/channel/message_size_filter.c \
     src/core/lib/compression/compression.c \
     src/core/lib/compression/message_compress.c \
     src/core/lib/debug/trace.c \
@@ -2797,6 +2813,7 @@ LIBGRPC_CRONET_SRC = \
     src/core/lib/http/httpcli.c \
     src/core/lib/http/parser.c \
     src/core/lib/iomgr/closure.c \
+    src/core/lib/iomgr/combiner.c \
     src/core/lib/iomgr/endpoint.c \
     src/core/lib/iomgr/endpoint_pair_posix.c \
     src/core/lib/iomgr/endpoint_pair_windows.c \
@@ -2839,7 +2856,6 @@ LIBGRPC_CRONET_SRC = \
     src/core/lib/iomgr/wakeup_fd_nospecial.c \
     src/core/lib/iomgr/wakeup_fd_pipe.c \
     src/core/lib/iomgr/wakeup_fd_posix.c \
-    src/core/lib/iomgr/workqueue_posix.c \
     src/core/lib/iomgr/workqueue_windows.c \
     src/core/lib/json/json.c \
     src/core/lib/json/json_reader.c \
@@ -3051,6 +3067,7 @@ LIBGRPC_TEST_UTIL_SRC = \
     src/core/lib/channel/handshaker.c \
     src/core/lib/channel/http_client_filter.c \
     src/core/lib/channel/http_server_filter.c \
+    src/core/lib/channel/message_size_filter.c \
     src/core/lib/compression/compression.c \
     src/core/lib/compression/message_compress.c \
     src/core/lib/debug/trace.c \
@@ -3058,6 +3075,7 @@ LIBGRPC_TEST_UTIL_SRC = \
     src/core/lib/http/httpcli.c \
     src/core/lib/http/parser.c \
     src/core/lib/iomgr/closure.c \
+    src/core/lib/iomgr/combiner.c \
     src/core/lib/iomgr/endpoint.c \
     src/core/lib/iomgr/endpoint_pair_posix.c \
     src/core/lib/iomgr/endpoint_pair_windows.c \
@@ -3100,7 +3118,6 @@ LIBGRPC_TEST_UTIL_SRC = \
     src/core/lib/iomgr/wakeup_fd_nospecial.c \
     src/core/lib/iomgr/wakeup_fd_pipe.c \
     src/core/lib/iomgr/wakeup_fd_posix.c \
-    src/core/lib/iomgr/workqueue_posix.c \
     src/core/lib/iomgr/workqueue_windows.c \
     src/core/lib/json/json.c \
     src/core/lib/json/json_reader.c \
@@ -3240,6 +3257,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/lib/channel/handshaker.c \
     src/core/lib/channel/http_client_filter.c \
     src/core/lib/channel/http_server_filter.c \
+    src/core/lib/channel/message_size_filter.c \
     src/core/lib/compression/compression.c \
     src/core/lib/compression/message_compress.c \
     src/core/lib/debug/trace.c \
@@ -3247,6 +3265,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/lib/http/httpcli.c \
     src/core/lib/http/parser.c \
     src/core/lib/iomgr/closure.c \
+    src/core/lib/iomgr/combiner.c \
     src/core/lib/iomgr/endpoint.c \
     src/core/lib/iomgr/endpoint_pair_posix.c \
     src/core/lib/iomgr/endpoint_pair_windows.c \
@@ -3289,7 +3308,6 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/lib/iomgr/wakeup_fd_nospecial.c \
     src/core/lib/iomgr/wakeup_fd_pipe.c \
     src/core/lib/iomgr/wakeup_fd_posix.c \
-    src/core/lib/iomgr/workqueue_posix.c \
     src/core/lib/iomgr/workqueue_windows.c \
     src/core/lib/json/json.c \
     src/core/lib/json/json_reader.c \
@@ -3389,6 +3407,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/census/operation.c \
     src/core/ext/census/placeholders.c \
     src/core/ext/census/resource.c \
+    src/core/ext/census/trace_context.c \
     src/core/ext/census/tracing.c \
     src/core/plugin_registry/grpc_unsecure_plugin_registry.c \
 
@@ -3576,6 +3595,7 @@ LIBGRPC++_SRC = \
     src/core/lib/channel/handshaker.c \
     src/core/lib/channel/http_client_filter.c \
     src/core/lib/channel/http_server_filter.c \
+    src/core/lib/channel/message_size_filter.c \
     src/core/lib/compression/compression.c \
     src/core/lib/compression/message_compress.c \
     src/core/lib/debug/trace.c \
@@ -3583,6 +3603,7 @@ LIBGRPC++_SRC = \
     src/core/lib/http/httpcli.c \
     src/core/lib/http/parser.c \
     src/core/lib/iomgr/closure.c \
+    src/core/lib/iomgr/combiner.c \
     src/core/lib/iomgr/endpoint.c \
     src/core/lib/iomgr/endpoint_pair_posix.c \
     src/core/lib/iomgr/endpoint_pair_windows.c \
@@ -3625,7 +3646,6 @@ LIBGRPC++_SRC = \
     src/core/lib/iomgr/wakeup_fd_nospecial.c \
     src/core/lib/iomgr/wakeup_fd_pipe.c \
     src/core/lib/iomgr/wakeup_fd_posix.c \
-    src/core/lib/iomgr/workqueue_posix.c \
     src/core/lib/iomgr/workqueue_windows.c \
     src/core/lib/json/json.c \
     src/core/lib/json/json_reader.c \
@@ -3754,6 +3774,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/service_type.h \
     include/grpc++/impl/codegen/status.h \
     include/grpc++/impl/codegen/status_code_enum.h \
+    include/grpc++/impl/codegen/status_helper.h \
     include/grpc++/impl/codegen/string_ref.h \
     include/grpc++/impl/codegen/stub_options.h \
     include/grpc++/impl/codegen/sync.h \
@@ -3859,6 +3880,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/service_type.h \
     include/grpc++/impl/codegen/status.h \
     include/grpc++/impl/codegen/status_code_enum.h \
+    include/grpc++/impl/codegen/status_helper.h \
     include/grpc++/impl/codegen/string_ref.h \
     include/grpc++/impl/codegen/stub_options.h \
     include/grpc++/impl/codegen/sync.h \
@@ -4082,6 +4104,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/service_type.h \
     include/grpc++/impl/codegen/status.h \
     include/grpc++/impl/codegen/status_code_enum.h \
+    include/grpc++/impl/codegen/status_helper.h \
     include/grpc++/impl/codegen/string_ref.h \
     include/grpc++/impl/codegen/stub_options.h \
     include/grpc++/impl/codegen/sync.h \
@@ -4199,6 +4222,7 @@ LIBGRPC++_UNSECURE_SRC = \
     src/core/lib/channel/handshaker.c \
     src/core/lib/channel/http_client_filter.c \
     src/core/lib/channel/http_server_filter.c \
+    src/core/lib/channel/message_size_filter.c \
     src/core/lib/compression/compression.c \
     src/core/lib/compression/message_compress.c \
     src/core/lib/debug/trace.c \
@@ -4206,6 +4230,7 @@ LIBGRPC++_UNSECURE_SRC = \
     src/core/lib/http/httpcli.c \
     src/core/lib/http/parser.c \
     src/core/lib/iomgr/closure.c \
+    src/core/lib/iomgr/combiner.c \
     src/core/lib/iomgr/endpoint.c \
     src/core/lib/iomgr/endpoint_pair_posix.c \
     src/core/lib/iomgr/endpoint_pair_windows.c \
@@ -4248,7 +4273,6 @@ LIBGRPC++_UNSECURE_SRC = \
     src/core/lib/iomgr/wakeup_fd_nospecial.c \
     src/core/lib/iomgr/wakeup_fd_pipe.c \
     src/core/lib/iomgr/wakeup_fd_posix.c \
-    src/core/lib/iomgr/workqueue_posix.c \
     src/core/lib/iomgr/workqueue_windows.c \
     src/core/lib/json/json.c \
     src/core/lib/json/json_reader.c \
@@ -4377,6 +4401,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/service_type.h \
     include/grpc++/impl/codegen/status.h \
     include/grpc++/impl/codegen/status_code_enum.h \
+    include/grpc++/impl/codegen/status_helper.h \
     include/grpc++/impl/codegen/string_ref.h \
     include/grpc++/impl/codegen/stub_options.h \
     include/grpc++/impl/codegen/sync.h \
@@ -7186,6 +7211,38 @@ endif
 endif
 
 
+CENSUS_TRACE_CONTEXT_TEST_SRC = \
+    test/core/census/trace_context_test.c \
+
+CENSUS_TRACE_CONTEXT_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(CENSUS_TRACE_CONTEXT_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/census_trace_context_test: openssl_dep_error
+
+else
+
+
+
+$(BINDIR)/$(CONFIG)/census_trace_context_test: $(CENSUS_TRACE_CONTEXT_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LD) $(LDFLAGS) $(CENSUS_TRACE_CONTEXT_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/census_trace_context_test
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/core/census/trace_context_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
+deps_census_trace_context_test: $(CENSUS_TRACE_CONTEXT_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(CENSUS_TRACE_CONTEXT_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 CHANNEL_CREATE_TEST_SRC = \
     test/core/surface/channel_create_test.c \
 
@@ -7378,6 +7435,38 @@ endif
 endif
 
 
+COMBINER_TEST_SRC = \
+    test/core/iomgr/combiner_test.c \
+
+COMBINER_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(COMBINER_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/combiner_test: openssl_dep_error
+
+else
+
+
+
+$(BINDIR)/$(CONFIG)/combiner_test: $(COMBINER_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LD) $(LDFLAGS) $(COMBINER_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/combiner_test
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/core/iomgr/combiner_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
+deps_combiner_test: $(COMBINER_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(COMBINER_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 COMPRESSION_TEST_SRC = \
     test/core/compression/compression_test.c \
 
@@ -8178,6 +8267,38 @@ endif
 endif
 
 
+GPR_MPSCQ_TEST_SRC = \
+    test/core/support/mpscq_test.c \
+
+GPR_MPSCQ_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(GPR_MPSCQ_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/gpr_mpscq_test: openssl_dep_error
+
+else
+
+
+
+$(BINDIR)/$(CONFIG)/gpr_mpscq_test: $(GPR_MPSCQ_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LD) $(LDFLAGS) $(GPR_MPSCQ_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/gpr_mpscq_test
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/core/support/mpscq_test.o:  $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
+deps_gpr_mpscq_test: $(GPR_MPSCQ_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(GPR_MPSCQ_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 GPR_PERCENT_ENCODING_TEST_SRC = \
     test/core/support/percent_encoding_test.c \
 

binding.gyp

@@ -515,6 +515,7 @@
         'src/core/lib/support/log_linux.c',
         'src/core/lib/support/log_posix.c',
         'src/core/lib/support/log_windows.c',
+        'src/core/lib/support/mpscq.c',
         'src/core/lib/support/murmur_hash.c',
         'src/core/lib/support/percent_encoding.c',
         'src/core/lib/support/slice.c',
@@ -572,6 +573,7 @@
         'src/core/lib/channel/handshaker.c',
         'src/core/lib/channel/http_client_filter.c',
         'src/core/lib/channel/http_server_filter.c',
+        'src/core/lib/channel/message_size_filter.c',
         'src/core/lib/compression/compression.c',
         'src/core/lib/compression/message_compress.c',
         'src/core/lib/debug/trace.c',
@@ -579,6 +581,7 @@
         'src/core/lib/http/httpcli.c',
         'src/core/lib/http/parser.c',
         'src/core/lib/iomgr/closure.c',
+        'src/core/lib/iomgr/combiner.c',
         'src/core/lib/iomgr/endpoint.c',
         'src/core/lib/iomgr/endpoint_pair_posix.c',
         'src/core/lib/iomgr/endpoint_pair_windows.c',
@@ -621,7 +624,6 @@
         'src/core/lib/iomgr/wakeup_fd_nospecial.c',
         'src/core/lib/iomgr/wakeup_fd_pipe.c',
         'src/core/lib/iomgr/wakeup_fd_posix.c',
-        'src/core/lib/iomgr/workqueue_posix.c',
         'src/core/lib/iomgr/workqueue_windows.c',
         'src/core/lib/json/json.c',
         'src/core/lib/json/json_reader.c',
@@ -751,6 +753,7 @@
         'src/core/ext/census/operation.c',
         'src/core/ext/census/placeholders.c',
         'src/core/ext/census/resource.c',
+        'src/core/ext/census/trace_context.c',
         'src/core/ext/census/tracing.c',
         'src/core/plugin_registry/grpc_plugin_registry.c',
       ],

build.yaml

@@ -29,6 +29,7 @@ filegroups:
   - src/core/ext/census/mlog.h
   - src/core/ext/census/resource.h
   - src/core/ext/census/rpc_metric_id.h
+  - src/core/ext/census/trace_context.h
   src:
   - src/core/ext/census/base_resources.c
   - src/core/ext/census/context.c
@@ -42,6 +43,7 @@ filegroups:
   - src/core/ext/census/operation.c
   - src/core/ext/census/placeholders.c
   - src/core/ext/census/resource.c
+  - src/core/ext/census/trace_context.c
   - src/core/ext/census/tracing.c
   plugin: census_grpc_plugin
   uses:
@@ -82,6 +84,7 @@ filegroups:
   - src/core/lib/support/backoff.h
   - src/core/lib/support/block_annotate.h
   - src/core/lib/support/env.h
+  - src/core/lib/support/mpscq.h
   - src/core/lib/support/murmur_hash.h
   - src/core/lib/support/percent_encoding.h
   - src/core/lib/support/stack_lockfree.h
@@ -111,6 +114,7 @@ filegroups:
   - src/core/lib/support/log_linux.c
   - src/core/lib/support/log_posix.c
   - src/core/lib/support/log_windows.c
+  - src/core/lib/support/mpscq.c
   - src/core/lib/support/murmur_hash.c
   - src/core/lib/support/percent_encoding.c
   - src/core/lib/support/slice.c
@@ -171,6 +175,7 @@ filegroups:
   - src/core/lib/channel/handshaker.h
   - src/core/lib/channel/http_client_filter.h
   - src/core/lib/channel/http_server_filter.h
+  - src/core/lib/channel/message_size_filter.h
   - src/core/lib/compression/algorithm_metadata.h
   - src/core/lib/compression/message_compress.h
   - src/core/lib/debug/trace.h
@@ -178,6 +183,7 @@ filegroups:
   - src/core/lib/http/httpcli.h
   - src/core/lib/http/parser.h
   - src/core/lib/iomgr/closure.h
+  - src/core/lib/iomgr/combiner.h
   - src/core/lib/iomgr/endpoint.h
   - src/core/lib/iomgr/endpoint_pair.h
   - src/core/lib/iomgr/error.h
@@ -217,7 +223,6 @@ filegroups:
   - src/core/lib/iomgr/wakeup_fd_pipe.h
   - src/core/lib/iomgr/wakeup_fd_posix.h
   - src/core/lib/iomgr/workqueue.h
-  - src/core/lib/iomgr/workqueue_posix.h
   - src/core/lib/iomgr/workqueue_windows.h
   - src/core/lib/json/json.h
   - src/core/lib/json/json_common.h
@@ -251,6 +256,7 @@ filegroups:
   - src/core/lib/channel/handshaker.c
   - src/core/lib/channel/http_client_filter.c
   - src/core/lib/channel/http_server_filter.c
+  - src/core/lib/channel/message_size_filter.c
   - src/core/lib/compression/compression.c
   - src/core/lib/compression/message_compress.c
   - src/core/lib/debug/trace.c
@@ -258,6 +264,7 @@ filegroups:
   - src/core/lib/http/httpcli.c
   - src/core/lib/http/parser.c
   - src/core/lib/iomgr/closure.c
+  - src/core/lib/iomgr/combiner.c
   - src/core/lib/iomgr/endpoint.c
   - src/core/lib/iomgr/endpoint_pair_posix.c
   - src/core/lib/iomgr/endpoint_pair_windows.c
@@ -300,7 +307,6 @@ filegroups:
   - src/core/lib/iomgr/wakeup_fd_nospecial.c
   - src/core/lib/iomgr/wakeup_fd_pipe.c
   - src/core/lib/iomgr/wakeup_fd_posix.c
-  - src/core/lib/iomgr/workqueue_posix.c
   - src/core/lib/iomgr/workqueue_windows.c
   - src/core/lib/json/json.c
   - src/core/lib/json/json_reader.c
@@ -754,6 +760,7 @@ filegroups:
   - include/grpc++/impl/codegen/service_type.h
   - include/grpc++/impl/codegen/status.h
   - include/grpc++/impl/codegen/status_code_enum.h
+  - include/grpc++/impl/codegen/status_helper.h
   - include/grpc++/impl/codegen/string_ref.h
   - include/grpc++/impl/codegen/stub_options.h
   - include/grpc++/impl/codegen/sync.h
@@ -1340,6 +1347,16 @@ targets:
   - grpc
   - gpr_test_util
   - gpr
+- name: census_trace_context_test
+  build: test
+  language: c
+  src:
+  - test/core/census/trace_context_test.c
+  deps:
+  - grpc_test_util
+  - grpc
+  - gpr_test_util
+  - gpr
 - name: channel_create_test
   build: test
   language: c
@@ -1404,6 +1421,17 @@ targets:
   - test/core/end2end/fuzzers/client_fuzzer_corpus
   dict: test/core/end2end/fuzzers/hpack.dictionary
   maxlen: 2048
+- name: combiner_test
+  cpu_cost: 30
+  build: test
+  language: c
+  src:
+  - test/core/iomgr/combiner_test.c
+  deps:
+  - grpc_test_util
+  - grpc
+  - gpr_test_util
+  - gpr
 - name: compression_test
   build: test
   language: c
@@ -1661,6 +1689,15 @@ targets:
   deps:
   - gpr_test_util
   - gpr
+- name: gpr_mpscq_test
+  cpu_cost: 30
+  build: test
+  language: c
+  src:
+  - test/core/support/mpscq_test.c
+  deps:
+  - gpr_test_util
+  - gpr
 - name: gpr_percent_encoding_test
   build: test
   language: c

config.m4

@@ -56,6 +56,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/support/log_linux.c \
     src/core/lib/support/log_posix.c \
     src/core/lib/support/log_windows.c \
+    src/core/lib/support/mpscq.c \
     src/core/lib/support/murmur_hash.c \
     src/core/lib/support/percent_encoding.c \
     src/core/lib/support/slice.c \
@@ -91,6 +92,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/channel/handshaker.c \
     src/core/lib/channel/http_client_filter.c \
     src/core/lib/channel/http_server_filter.c \
+    src/core/lib/channel/message_size_filter.c \
     src/core/lib/compression/compression.c \
     src/core/lib/compression/message_compress.c \
     src/core/lib/debug/trace.c \
@@ -98,6 +100,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/http/httpcli.c \
     src/core/lib/http/parser.c \
     src/core/lib/iomgr/closure.c \
+    src/core/lib/iomgr/combiner.c \
     src/core/lib/iomgr/endpoint.c \
     src/core/lib/iomgr/endpoint_pair_posix.c \
     src/core/lib/iomgr/endpoint_pair_windows.c \
@@ -140,7 +143,6 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/iomgr/wakeup_fd_nospecial.c \
     src/core/lib/iomgr/wakeup_fd_pipe.c \
     src/core/lib/iomgr/wakeup_fd_posix.c \
-    src/core/lib/iomgr/workqueue_posix.c \
     src/core/lib/iomgr/workqueue_windows.c \
     src/core/lib/json/json.c \
     src/core/lib/json/json_reader.c \
@@ -270,6 +272,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/census/operation.c \
     src/core/ext/census/placeholders.c \
     src/core/ext/census/resource.c \
+    src/core/ext/census/trace_context.c \
     src/core/ext/census/tracing.c \
     src/core/plugin_registry/grpc_plugin_registry.c \
     src/boringssl/err_data.c \

doc/core/pending_api_cleanups.md

@@ -0,0 +1,15 @@
+There are times when we make changes that include a temporary shim for
+backward-compatibility (e.g., a macro or some other function to preserve
+the original API) to avoid having to bump the major version number in
+the next release.  However, when we do eventually want to release a
+feature that does change the API in a non-backward-compatible way, we
+will wind up bumping the major version number anyway, at which point we
+can take the opportunity to clean up any pending backward-compatibility
+shims.
+
+This file lists all pending backward-compatibility changes that should
+be cleaned up the next time we are going to bump the major version
+number:
+
+- remove `GRPC_ARG_MAX_MESSAGE_LENGTH` channel arg from
+  `include/grpc/impl/codegen/grpc_types.h` (commit `af00d8b`)

doc/environment_variables.md

@@ -0,0 +1,64 @@
+gRPC environment variables
+--------------------------
+
+gRPC C core based implementations (those contained in this repository) expose
+some configuration as environment variables that can be set.
+
+* GRPC_ABORT_ON_LEAKS
+  A debugging aid to cause a call to abort() when gRPC objects are leaked past
+  grpc_shutdown(). Set to 1 to cause the abort, if unset or 0 it does not
+  abort the process.
+
+* GRPC_GOOGLE_CREDENTIALS_ENV_VAR
+  The path to find the credentials to use when Google credentials are created
+
+* GRPC_SSL_CIPHER_SUITES
+  A colon separated list of cipher suites to use with OpenSSL
+  Defaults to:
+    ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-GCM-SHA384
+
+* GRPC_POLL_STRATEGY [posix-style environments only]
+  Declares which polling engines to try when starting gRPC.
+  This is a comma-separated list of engines, which are tried in priority order
+  first -> last.
+  Available polling engines include:
+  - epoll (linux-only) - a polling engine based around the epoll family of
+    system calls
+  - poll - a portable polling engine based around poll(), intended to be a
+    fallback engine when nothing better exists
+  - legacy - the (deprecated) original polling engine for gRPC
+
+* GRPC_TRACE
+  A comma separated list of tracers that provide additional insight into how
+  gRPC C core is processing requests via debug logs. Available tracers include:
+  - api - traces api calls to the C core
+  - channel - traces operations on the C core channel stack
+  - combiner - traces combiner lock state
+  - compression - traces compression operations
+  - connectivity_state - traces connectivity state changes to channels
+  - channel_stack_builder - traces information about channel stacks being built
+  - http - traces state in the http2 transport engine
+  - http1 - traces HTTP/1.x operations performed by gRPC
+  - flowctl - traces http2 flow control
+  - op_failure - traces error information when failure is pushed onto a
+    completion queue
+  - pending_tags - [debug builds only] traces still-in-progress tags on
+    completion queues
+  - round_robin - traces the round_robin load balancing policy
+  - glb - traces the grpclb load balancer
+  - queue_pluck
+  - queue_timeout
+  - server_channel - lightweight trace of significant server channel events
+  - secure_endpoint - traces bytes flowing through encrypted channels
+  - transport_security - traces metadata about secure channel establishment
+  - tcp - traces bytes in and out of a channel
+  'all' can additionally be used to turn all traces on.
+  Individual traces can be disabled by prefixing them with '-'.
+  Example:
+   export GRPC_TRACE=all,-pending_tags
+
+* GRPC_VERBOSITY
+  Default gRPC logging verbosity - one of:
+  - DEBUG - log all gRPC messages
+  - INFO - log INFO and ERROR message
+  - ERROR - log only errors

doc/http-grpc-status-mapping.md

@@ -0,0 +1,30 @@
+# HTTP to gRPC Status Code Mapping
+
+Since intermediaries are a common part of HTTP infrastructure some responses to
+gRPC requests may be received that do not include the grpc-status header. In
+some cases mapping error codes from an intermediary allows the gRPC client to
+behave more appropriately to the error situation without overloading the
+semantics of either error code.
+
+This table is to be used _only_ for clients that received a response that did
+not include grpc-status. If grpc-status was provided, it _must_ be used. Servers
+_must not_ use this table to determine an HTTP status code to use; the mappings
+are neither symmetric nor 1-to-1.
+
+| HTTP Status Code           | gRPC Status Code   |
+|----------------------------|--------------------|
+| 400 Bad Request            | INTERNAL           |
+| 401 Unauthorized           | UNAUTHENTICATED    |
+| 403 Forbidden              | PERMISSION\_DENIED |
+| 404 Not Found              | UNIMPLEMENTED      |
+| 429 Too Many Requests      | UNAVAILABLE        |
+| 502 Bad Gateway            | UNAVAILABLE        |
+| 503 Service Unavailable    | UNAVAILABLE        |
+| 504 Gateway Timeout        | UNAVAILABLE        |
+| _All other codes_          | UNKNOWN            |
+
+Technically, 1xx should have the entire header skipped and a subsequent header
+be read. See RFC 7540 §8.1.
+
+200 is UNKNOWN because there should be a grpc-status in case of truly OK
+response.

doc/server_reflection_tutorial.md

@@ -0,0 +1,192 @@
+# gRPC Server Reflection Tutorial
+
+gRPC Server Reflection provides information about publicly-accessible gRPC
+services on a server, and assists clients at runtime to construct RPC
+requests and responses without precompiled service information. It is used by
+gRPC CLI, which can be used to introspect server protos and send/receive test
+RPCs.
+
+## Enable Server Reflection
+
+### Enable server reflection in C++ servers
+
+C++ Server Reflection is an add-on library, `libgrpc++_reflction`. To enable C++
+server reflection, you can link this library to your server binary.
+
+Some platforms (e.g. Ubuntu 11.10 onwards) only link in libraries that directly
+contain symbols used by the application. On these platforms, LD flag
+`--no-as-needed` is needed for for dynamic linking and `--whole-archive` is
+needed for for static linking.
+
+This [Makefile](../examples/cpp/helloworld/Makefile#L37#L45) demonstrates
+enabling c++ server reflection on Linux and MacOS.
+
+## Test services using Server Reflection
+
+After enabling Server Reflection in a server application, you can use gRPC CLI
+to test its services.
+
+Instructions on how to use gRPC CLI can be found at
+[command_line_tool.md](command_line_tool.md), or using `grpc_cli help` command.
+
+Here we use `examples/cpp/helloworld` as an example to show the use of gRPC
+Server Reflection and gRPC CLI. First, we need to build gRPC CLI and setup an
+example server with Server Reflection enabled.
+
+- Setup an example server
+
+  Server Reflection has already been enabled in the
+  [Makefile](../examples/cpp/helloworld/Makefile) of the helloworld example. We
+  can simply make it and run the greeter_server.
+
+  ```sh
+  $ make -C examples/cpp/helloworld
+  $ examples/cpp/helloworld/greeter_server &
+  ```
+
+- Build gRPC CLI
+
+  ```sh
+  make grpc_cli
+  cd bins/opt
+  ```
+
+  gRPC CLI binary `grpc_cli` can be found at `bins/opt/` folder. This tool is
+  still new and does not have a `make install` target yet.
+
+### List services
+
+`grpc_cli ls` command lists services and methods exposed at a given port
+
+- List all the services exposed at a given port
+
+  ```sh
+  $ grpc_cli ls localhost:50051
+  ```
+
+  output:
+  ```sh
+  helloworld.Greeter
+  grpc.reflection.v1alpha.ServerReflection
+  ```
+
+- List one service with details
+
+  `grpc_cli ls` command inspects a service given its full name (in the format of
+  \<package\>.\<service\>). It can print information with a long listing format
+  when `-l` flag is set. This flag can be used to get more details about a
+  service.
+
+  ```sh
+  $ grpc_cli ls localhost:50051 helloworld.Greeter -l
+  ```
+
+  output:
+  ```sh
+  filename: helloworld.proto
+  package: helloworld;
+  service Greeter {
+    rpc SayHello(helloworld.HelloRequest) returns (helloworld.HelloReply) {}
+  }
+
+  ```
+
+### List methods
+
+- List one method with details
+
+  `grpc_cli ls` command also inspects a method given its full name (in the
+  format of \<package\>.\<service\>.\<method\>).
+
+  ```sh
+  $ grpc_cli ls localhost:50051 helloworld.Greeter.SayHello -l
+  ```
+
+  output:
+  ```sh
+    rpc SayHello(helloworld.HelloRequest) returns (helloworld.HelloReply) {}
+  ```
+
+### Inspect message types
+
+We can use`grpc_cli type` command to inspect request/response types given the
+full name of the type (in the format of \<package\>.\<type\>).
+
+- Get information about the request type
+
+  ```sh
+  $ grpc_cli type localhost:50051 helloworld.HelloRequest
+  ```
+
+  output:
+  ```sh
+  message HelloRequest {
+    optional string name = 1;
+  }
+  ```
+
+### Call a remote method
+
+We can send RPCs to a server and get responses using `grpc_cli call` command.
+
+- Call a unary method
+
+  ```sh
+  $ grpc_cli call localhost:50051 SayHello "name: 'gRPC CLI'"
+  ```
+
+  output:
+  ```sh
+  message: "Hello gRPC CLI"
+  ```
+
+## Use Server Reflection in a C++ client
+
+Server Reflection can be used by clients to get information about gRPC services
+at runtime. We've provided a descriptor database called
+[grpc::ProtoReflectionDescriptorDatabase](../test/cpp/util/proto_reflection_descriptor_database.h)
+which implements the
+[google::protobuf::DescriptorDatabase](https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.descriptor_database#DescriptorDatabase)
+interface. It manages the communication between clients and reflection services
+and the storage of received information. Clients can use it as using a local
+descriptor database.
+
+- To use Server Reflection with grpc::ProtoReflectionDescriptorDatabase, first
+  initialize an instance with a grpc::Channel.
+
+  ```c++
+  std::shared_ptr<grpc::Channel> channel =
+      grpc::CreateChannel(server_address, server_cred);
+  grpc::ProtoReflectionDescriptorDatabase reflection_db(channel);
+  ```
+
+- Then use this instance to feed a
+  [google::protobuf::DescriptorPool](https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.descriptor#DescriptorPool).
+
+  ```c++
+  google::protobuf::DescriptorPool desc_pool(&reflection_db);
+  ```
+
+- Example usage of this descriptor pool
+
+  * Get Service/method descriptors.
+
+    ```c++
+    const google::protobuf::ServiceDescriptor* service_desc =
+        desc_pool->FindServiceByName("helloworld.Greeter");
+    const google::protobuf::MethodDescriptor* method_desc =
+        desc_pool->FindMethodByName("helloworld.Greeter.SayHello");
+    ```
+
+  * Get message type descriptors.
+
+    ```c++
+    const google::protobuf::Descriptor* request_desc =
+        desc_pool->FindMessageTypeByName("helloworld.HelloRequest");
+    ```
+
+  * Feed [google::protobuf::DynamicMessageFactory](https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.dynamic_message#DynamicMessageFactory).
+
+    ```c++
+    google::protobuf::DynamicMessageFactory(&desc_pool);
+    ```

etc/README.md

@@ -0,0 +1,4 @@
+The roots.pem file is periodically generated from:
+https://hg.mozilla.org/mozilla-central/raw-file/tip/security/nss/lib/ckfw/builtins/certdata.txt
+using
+https://github.com/agl/extract-nss-root-certs

etc/roots.pem

@@ -5387,3 +5387,42 @@ BggqhkjOPQQDAwNpADBmAjEAj6jcnboMBBf6Fek9LykBl7+BFjNAk2z8+e2AcG+q
 j9uEwov1NcoG3GRvaBbhj5G5AjEA2Euly8LQCGzpGPta3U1fJAuwACEl74+nBCZx
 4nxp5V2a+EEfOzmTk51V6s2N8fvB
 -----END CERTIFICATE-----
+
+# Issuer: CN=ISRG Root X1 O=Internet Security Research Group
+# Subject: CN=ISRG Root X1 O=Internet Security Research Group
+# Label: "ISRG Root X1"
+# Serial: 172886928669790476064670243504169061120
+# MD5 Fingerprint: 0c:d2:f9:e0:da:17:73:e9:ed:86:4d:a5:e3:70:e7:4e
+# SHA1 Fingerprint: ca:bd:2a:79:a1:07:6a:31:f2:1d:25:36:35:cb:03:9d:43:29:a5:e8
+# SHA256 Fingerprint: 96:bc:ec:06:26:49:76:f3:74:60:77:9a:cf:28:c5:a7:cf:e8:a3:c0:aa:e1:1a:8f:fc:ee:05:c0:bd:df:08:c6
+-----BEGIN CERTIFICATE-----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=
+-----END CERTIFICATE-----

examples/cpp/helloworld/greeter_async_client.cc

@@ -36,6 +36,7 @@
 #include <string>
 
 #include <grpc++/grpc++.h>
+#include <grpc/support/log.h>
 
 #include "helloworld.grpc.pb.h"
 

examples/cpp/helloworld/greeter_async_client2.cc

@@ -36,6 +36,7 @@
 #include <string>
 
 #include <grpc++/grpc++.h>
+#include <grpc/support/log.h>
 #include <thread>
 
 #include "helloworld.grpc.pb.h"

examples/cpp/helloworld/greeter_async_server.cc

@@ -37,6 +37,7 @@
 #include <thread>
 
 #include <grpc++/grpc++.h>
+#include <grpc/support/log.h>
 
 #include "helloworld.grpc.pb.h"
 

examples/php/route_guide/run_route_guide_client.sh

@@ -30,5 +30,6 @@
 
 set -e
 cd $(dirname $0)
-php $extension_dir -d extension=grpc.so -d max_execution_time=300 \
-  route_guide_client.php ../../node/route_guide/route_guide_db.json
+php -d extension=grpc.so -d max_execution_time=300 \
+  route_guide_client.php \
+  ../../node/static_codegen/route_guide/route_guide_db.json

gRPC-Core.podspec

@@ -193,6 +193,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/support/backoff.h',
                       'src/core/lib/support/block_annotate.h',
                       'src/core/lib/support/env.h',
+                      'src/core/lib/support/mpscq.h',
                       'src/core/lib/support/murmur_hash.h',
                       'src/core/lib/support/percent_encoding.h',
                       'src/core/lib/support/stack_lockfree.h',
@@ -221,6 +222,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/support/log_linux.c',
                       'src/core/lib/support/log_posix.c',
                       'src/core/lib/support/log_windows.c',
+                      'src/core/lib/support/mpscq.c',
                       'src/core/lib/support/murmur_hash.c',
                       'src/core/lib/support/percent_encoding.c',
                       'src/core/lib/support/slice.c',
@@ -256,6 +258,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/channel/handshaker.h',
                       'src/core/lib/channel/http_client_filter.h',
                       'src/core/lib/channel/http_server_filter.h',
+                      'src/core/lib/channel/message_size_filter.h',
                       'src/core/lib/compression/algorithm_metadata.h',
                       'src/core/lib/compression/message_compress.h',
                       'src/core/lib/debug/trace.h',
@@ -263,6 +266,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/http/httpcli.h',
                       'src/core/lib/http/parser.h',
                       'src/core/lib/iomgr/closure.h',
+                      'src/core/lib/iomgr/combiner.h',
                       'src/core/lib/iomgr/endpoint.h',
                       'src/core/lib/iomgr/endpoint_pair.h',
                       'src/core/lib/iomgr/error.h',
@@ -302,7 +306,6 @@ Pod::Spec.new do |s|
                       'src/core/lib/iomgr/wakeup_fd_pipe.h',
                       'src/core/lib/iomgr/wakeup_fd_posix.h',
                       'src/core/lib/iomgr/workqueue.h',
-                      'src/core/lib/iomgr/workqueue_posix.h',
                       'src/core/lib/iomgr/workqueue_windows.h',
                       'src/core/lib/json/json.h',
                       'src/core/lib/json/json_common.h',
@@ -406,6 +409,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/census/mlog.h',
                       'src/core/ext/census/resource.h',
                       'src/core/ext/census/rpc_metric_id.h',
+                      'src/core/ext/census/trace_context.h',
                       'src/core/lib/surface/init.c',
                       'src/core/lib/channel/channel_args.c',
                       'src/core/lib/channel/channel_stack.c',
@@ -415,6 +419,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/channel/handshaker.c',
                       'src/core/lib/channel/http_client_filter.c',
                       'src/core/lib/channel/http_server_filter.c',
+                      'src/core/lib/channel/message_size_filter.c',
                       'src/core/lib/compression/compression.c',
                       'src/core/lib/compression/message_compress.c',
                       'src/core/lib/debug/trace.c',
@@ -422,6 +427,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/http/httpcli.c',
                       'src/core/lib/http/parser.c',
                       'src/core/lib/iomgr/closure.c',
+                      'src/core/lib/iomgr/combiner.c',
                       'src/core/lib/iomgr/endpoint.c',
                       'src/core/lib/iomgr/endpoint_pair_posix.c',
                       'src/core/lib/iomgr/endpoint_pair_windows.c',
@@ -464,7 +470,6 @@ Pod::Spec.new do |s|
                       'src/core/lib/iomgr/wakeup_fd_nospecial.c',
                       'src/core/lib/iomgr/wakeup_fd_pipe.c',
                       'src/core/lib/iomgr/wakeup_fd_posix.c',
-                      'src/core/lib/iomgr/workqueue_posix.c',
                       'src/core/lib/iomgr/workqueue_windows.c',
                       'src/core/lib/json/json.c',
                       'src/core/lib/json/json_reader.c',
@@ -594,6 +599,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/census/operation.c',
                       'src/core/ext/census/placeholders.c',
                       'src/core/ext/census/resource.c',
+                      'src/core/ext/census/trace_context.c',
                       'src/core/ext/census/tracing.c',
                       'src/core/plugin_registry/grpc_plugin_registry.c'
 
@@ -601,6 +607,7 @@ Pod::Spec.new do |s|
                               'src/core/lib/support/backoff.h',
                               'src/core/lib/support/block_annotate.h',
                               'src/core/lib/support/env.h',
+                              'src/core/lib/support/mpscq.h',
                               'src/core/lib/support/murmur_hash.h',
                               'src/core/lib/support/percent_encoding.h',
                               'src/core/lib/support/stack_lockfree.h',
@@ -618,6 +625,7 @@ Pod::Spec.new do |s|
                               'src/core/lib/channel/handshaker.h',
                               'src/core/lib/channel/http_client_filter.h',
                               'src/core/lib/channel/http_server_filter.h',
+                              'src/core/lib/channel/message_size_filter.h',
                               'src/core/lib/compression/algorithm_metadata.h',
                               'src/core/lib/compression/message_compress.h',
                               'src/core/lib/debug/trace.h',
@@ -625,6 +633,7 @@ Pod::Spec.new do |s|
                               'src/core/lib/http/httpcli.h',
                               'src/core/lib/http/parser.h',
                               'src/core/lib/iomgr/closure.h',
+                              'src/core/lib/iomgr/combiner.h',
                               'src/core/lib/iomgr/endpoint.h',
                               'src/core/lib/iomgr/endpoint_pair.h',
                               'src/core/lib/iomgr/error.h',
@@ -664,7 +673,6 @@ Pod::Spec.new do |s|
                               'src/core/lib/iomgr/wakeup_fd_pipe.h',
                               'src/core/lib/iomgr/wakeup_fd_posix.h',
                               'src/core/lib/iomgr/workqueue.h',
-                              'src/core/lib/iomgr/workqueue_posix.h',
                               'src/core/lib/iomgr/workqueue_windows.h',
                               'src/core/lib/json/json.h',
                               'src/core/lib/json/json_common.h',
@@ -767,7 +775,8 @@ Pod::Spec.new do |s|
                               'src/core/ext/census/grpc_filter.h',
                               'src/core/ext/census/mlog.h',
                               'src/core/ext/census/resource.h',
-                              'src/core/ext/census/rpc_metric_id.h'
+                              'src/core/ext/census/rpc_metric_id.h',
+                              'src/core/ext/census/trace_context.h'
   end
 
   s.subspec 'Cronet-Interface' do |ss|

grpc.gemspec

@@ -87,6 +87,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/support/backoff.h )
   s.files += %w( src/core/lib/support/block_annotate.h )
   s.files += %w( src/core/lib/support/env.h )
+  s.files += %w( src/core/lib/support/mpscq.h )
   s.files += %w( src/core/lib/support/murmur_hash.h )
   s.files += %w( src/core/lib/support/percent_encoding.h )
   s.files += %w( src/core/lib/support/stack_lockfree.h )
@@ -115,6 +116,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/support/log_linux.c )
   s.files += %w( src/core/lib/support/log_posix.c )
   s.files += %w( src/core/lib/support/log_windows.c )
+  s.files += %w( src/core/lib/support/mpscq.c )
   s.files += %w( src/core/lib/support/murmur_hash.c )
   s.files += %w( src/core/lib/support/percent_encoding.c )
   s.files += %w( src/core/lib/support/slice.c )
@@ -176,6 +178,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/channel/handshaker.h )
   s.files += %w( src/core/lib/channel/http_client_filter.h )
   s.files += %w( src/core/lib/channel/http_server_filter.h )
+  s.files += %w( src/core/lib/channel/message_size_filter.h )
   s.files += %w( src/core/lib/compression/algorithm_metadata.h )
   s.files += %w( src/core/lib/compression/message_compress.h )
   s.files += %w( src/core/lib/debug/trace.h )
@@ -183,6 +186,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/http/httpcli.h )
   s.files += %w( src/core/lib/http/parser.h )
   s.files += %w( src/core/lib/iomgr/closure.h )
+  s.files += %w( src/core/lib/iomgr/combiner.h )
   s.files += %w( src/core/lib/iomgr/endpoint.h )
   s.files += %w( src/core/lib/iomgr/endpoint_pair.h )
   s.files += %w( src/core/lib/iomgr/error.h )
@@ -222,7 +226,6 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/iomgr/wakeup_fd_pipe.h )
   s.files += %w( src/core/lib/iomgr/wakeup_fd_posix.h )
   s.files += %w( src/core/lib/iomgr/workqueue.h )
-  s.files += %w( src/core/lib/iomgr/workqueue_posix.h )
   s.files += %w( src/core/lib/iomgr/workqueue_windows.h )
   s.files += %w( src/core/lib/json/json.h )
   s.files += %w( src/core/lib/json/json_common.h )
@@ -326,6 +329,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/census/mlog.h )
   s.files += %w( src/core/ext/census/resource.h )
   s.files += %w( src/core/ext/census/rpc_metric_id.h )
+  s.files += %w( src/core/ext/census/trace_context.h )
   s.files += %w( src/core/lib/surface/init.c )
   s.files += %w( src/core/lib/channel/channel_args.c )
   s.files += %w( src/core/lib/channel/channel_stack.c )
@@ -335,6 +339,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/channel/handshaker.c )
   s.files += %w( src/core/lib/channel/http_client_filter.c )
   s.files += %w( src/core/lib/channel/http_server_filter.c )
+  s.files += %w( src/core/lib/channel/message_size_filter.c )
   s.files += %w( src/core/lib/compression/compression.c )
   s.files += %w( src/core/lib/compression/message_compress.c )
   s.files += %w( src/core/lib/debug/trace.c )
@@ -342,6 +347,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/http/httpcli.c )
   s.files += %w( src/core/lib/http/parser.c )
   s.files += %w( src/core/lib/iomgr/closure.c )
+  s.files += %w( src/core/lib/iomgr/combiner.c )
   s.files += %w( src/core/lib/iomgr/endpoint.c )
   s.files += %w( src/core/lib/iomgr/endpoint_pair_posix.c )
   s.files += %w( src/core/lib/iomgr/endpoint_pair_windows.c )
@@ -384,7 +390,6 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/iomgr/wakeup_fd_nospecial.c )
   s.files += %w( src/core/lib/iomgr/wakeup_fd_pipe.c )
   s.files += %w( src/core/lib/iomgr/wakeup_fd_posix.c )
-  s.files += %w( src/core/lib/iomgr/workqueue_posix.c )
   s.files += %w( src/core/lib/iomgr/workqueue_windows.c )
   s.files += %w( src/core/lib/json/json.c )
   s.files += %w( src/core/lib/json/json_reader.c )
@@ -514,6 +519,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/census/operation.c )
   s.files += %w( src/core/ext/census/placeholders.c )
   s.files += %w( src/core/ext/census/resource.c )
+  s.files += %w( src/core/ext/census/trace_context.c )
   s.files += %w( src/core/ext/census/tracing.c )
   s.files += %w( src/core/plugin_registry/grpc_plugin_registry.c )
   s.files += %w( third_party/boringssl/crypto/aes/internal.h )

include/grpc++/impl/codegen/call.h

@@ -46,6 +46,7 @@
 #include <grpc++/impl/codegen/core_codegen_interface.h>
 #include <grpc++/impl/codegen/serialization_traits.h>
 #include <grpc++/impl/codegen/status.h>
+#include <grpc++/impl/codegen/status_helper.h>
 #include <grpc++/impl/codegen/string_ref.h>
 
 #include <grpc/impl/codegen/compression_types.h>
@@ -174,7 +175,7 @@ template <int I>
 class CallNoOp {
  protected:
   void AddOp(grpc_op* ops, size_t* nops) {}
-  void FinishOp(bool* status, int max_message_size) {}
+  void FinishOp(bool* status, int max_receive_message_size) {}
 };
 
 class CallOpSendInitialMetadata {
@@ -212,7 +213,7 @@ class CallOpSendInitialMetadata {
     op->data.send_initial_metadata.maybe_compression_level.level =
         maybe_compression_level_.level;
   }
-  void FinishOp(bool* status, int max_message_size) {
+  void FinishOp(bool* status, int max_receive_message_size) {
     if (!send_) return;
     g_core_codegen_interface->gpr_free(initial_metadata_);
     send_ = false;
@@ -252,7 +253,7 @@ class CallOpSendMessage {
     // Flags are per-message: clear them after use.
     write_options_.Clear();
   }
-  void FinishOp(bool* status, int max_message_size) {
+  void FinishOp(bool* status, int max_receive_message_size) {
     if (own_buf_) g_core_codegen_interface->grpc_byte_buffer_destroy(send_buf_);
     send_buf_ = nullptr;
   }
@@ -300,13 +301,14 @@ class CallOpRecvMessage {
     op->data.recv_message = &recv_buf_;
   }
 
-  void FinishOp(bool* status, int max_message_size) {
+  void FinishOp(bool* status, int max_receive_message_size) {
     if (message_ == nullptr) return;
     if (recv_buf_) {
       if (*status) {
-        got_message = *status = SerializationTraits<R>::Deserialize(
-                                    recv_buf_, message_, max_message_size)
-                                    .ok();
+        got_message = *status =
+            SerializationTraits<R>::Deserialize(recv_buf_, message_,
+                                                max_receive_message_size)
+                .ok();
       } else {
         got_message = false;
         g_core_codegen_interface->grpc_byte_buffer_destroy(recv_buf_);
@@ -329,7 +331,8 @@ class CallOpRecvMessage {
 namespace CallOpGenericRecvMessageHelper {
 class DeserializeFunc {
  public:
-  virtual Status Deserialize(grpc_byte_buffer* buf, int max_message_size) = 0;
+  virtual Status Deserialize(grpc_byte_buffer* buf,
+                             int max_receive_message_size) = 0;
   virtual ~DeserializeFunc() {}
 };
 
@@ -338,8 +341,9 @@ class DeserializeFuncType GRPC_FINAL : public DeserializeFunc {
  public:
   DeserializeFuncType(R* message) : message_(message) {}
   Status Deserialize(grpc_byte_buffer* buf,
-                     int max_message_size) GRPC_OVERRIDE {
-    return SerializationTraits<R>::Deserialize(buf, message_, max_message_size);
+                     int max_receive_message_size) GRPC_OVERRIDE {
+    return SerializationTraits<R>::Deserialize(buf, message_,
+                                               max_receive_message_size);
   }
 
   ~DeserializeFuncType() GRPC_OVERRIDE {}
@@ -378,12 +382,13 @@ class CallOpGenericRecvMessage {
     op->data.recv_message = &recv_buf_;
   }
 
-  void FinishOp(bool* status, int max_message_size) {
+  void FinishOp(bool* status, int max_receive_message_size) {
     if (!deserialize_) return;
     if (recv_buf_) {
       if (*status) {
         got_message = true;
-        *status = deserialize_->Deserialize(recv_buf_, max_message_size).ok();
+        *status =
+            deserialize_->Deserialize(recv_buf_, max_receive_message_size).ok();
       } else {
         got_message = false;
         g_core_codegen_interface->grpc_byte_buffer_destroy(recv_buf_);
@@ -417,7 +422,7 @@ class CallOpClientSendClose {
     op->flags = 0;
     op->reserved = NULL;
   }
-  void FinishOp(bool* status, int max_message_size) { send_ = false; }
+  void FinishOp(bool* status, int max_receive_message_size) { send_ = false; }
 
  private:
   bool send_;
@@ -433,7 +438,7 @@ class CallOpServerSendStatus {
     trailing_metadata_count_ = trailing_metadata.size();
     trailing_metadata_ = FillMetadataArray(trailing_metadata);
     send_status_available_ = true;
-    send_status_code_ = static_cast<grpc_status_code>(status.error_code());
+    send_status_code_ = static_cast<grpc_status_code>(GetCanonicalCode(status));
     send_status_details_ = status.error_message();
   }
 
@@ -452,7 +457,7 @@ class CallOpServerSendStatus {
     op->reserved = NULL;
   }
 
-  void FinishOp(bool* status, int max_message_size) {
+  void FinishOp(bool* status, int max_receive_message_size) {
     if (!send_status_available_) return;
     g_core_codegen_interface->gpr_free(trailing_metadata_);
     send_status_available_ = false;
@@ -485,7 +490,7 @@ class CallOpRecvInitialMetadata {
     op->flags = 0;
     op->reserved = NULL;
   }
-  void FinishOp(bool* status, int max_message_size) {
+  void FinishOp(bool* status, int max_receive_message_size) {
     if (recv_initial_metadata_ == nullptr) return;
     FillMetadataMap(&recv_initial_metadata_arr_, recv_initial_metadata_);
     recv_initial_metadata_ = nullptr;
@@ -524,7 +529,7 @@ class CallOpClientRecvStatus {
     op->reserved = NULL;
   }
 
-  void FinishOp(bool* status, int max_message_size) {
+  void FinishOp(bool* status, int max_receive_message_size) {
     if (recv_status_ == nullptr) return;
     FillMetadataMap(&recv_trailing_metadata_arr_, recv_trailing_metadata_);
     *recv_status_ = Status(
@@ -561,13 +566,13 @@ class CallOpSetCollectionInterface
 /// API.
 class CallOpSetInterface : public CompletionQueueTag {
  public:
-  CallOpSetInterface() : max_message_size_(0) {}
+  CallOpSetInterface() : max_receive_message_size_(0) {}
   /// Fills in grpc_op, starting from ops[*nops] and moving
   /// upwards.
   virtual void FillOps(grpc_op* ops, size_t* nops) = 0;
 
-  void set_max_message_size(int max_message_size) {
-    max_message_size_ = max_message_size;
+  void set_max_receive_message_size(int max_receive_message_size) {
+    max_receive_message_size_ = max_receive_message_size;
   }
 
   /// Mark this as belonging to a collection if needed
@@ -576,7 +581,7 @@ class CallOpSetInterface : public CompletionQueueTag {
   }
 
  protected:
-  int max_message_size_;
+  int max_receive_message_size_;
   std::shared_ptr<CallOpSetCollectionInterface> collection_;
 };
 
@@ -608,12 +613,12 @@ class CallOpSet : public CallOpSetInterface,
   }
 
   bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE {
-    this->Op1::FinishOp(status, max_message_size_);
-    this->Op2::FinishOp(status, max_message_size_);
-    this->Op3::FinishOp(status, max_message_size_);
-    this->Op4::FinishOp(status, max_message_size_);
-    this->Op5::FinishOp(status, max_message_size_);
-    this->Op6::FinishOp(status, max_message_size_);
+    this->Op1::FinishOp(status, max_receive_message_size_);
+    this->Op2::FinishOp(status, max_receive_message_size_);
+    this->Op3::FinishOp(status, max_receive_message_size_);
+    this->Op4::FinishOp(status, max_receive_message_size_);
+    this->Op5::FinishOp(status, max_receive_message_size_);
+    this->Op6::FinishOp(status, max_receive_message_size_);
     *tag = return_tag_;
     collection_.reset();  // drop the ref at this point
     return true;
@@ -645,18 +650,21 @@ class Call GRPC_FINAL {
  public:
   /* call is owned by the caller */
   Call(grpc_call* call, CallHook* call_hook, CompletionQueue* cq)
-      : call_hook_(call_hook), cq_(cq), call_(call), max_message_size_(-1) {}
+      : call_hook_(call_hook),
+        cq_(cq),
+        call_(call),
+        max_receive_message_size_(-1) {}
 
   Call(grpc_call* call, CallHook* call_hook, CompletionQueue* cq,
-       int max_message_size)
+       int max_receive_message_size)
       : call_hook_(call_hook),
         cq_(cq),
         call_(call),
-        max_message_size_(max_message_size) {}
+        max_receive_message_size_(max_receive_message_size) {}
 
   void PerformOps(CallOpSetInterface* ops) {
-    if (max_message_size_ > 0) {
-      ops->set_max_message_size(max_message_size_);
+    if (max_receive_message_size_ > 0) {
+      ops->set_max_receive_message_size(max_receive_message_size_);
     }
     call_hook_->PerformOpsOnCall(ops, this);
   }
@@ -664,13 +672,13 @@ class Call GRPC_FINAL {
   grpc_call* call() const { return call_; }
   CompletionQueue* cq() const { return cq_; }
 
-  int max_message_size() const { return max_message_size_; }
+  int max_receive_message_size() { return max_receive_message_size_; }
 
  private:
   CallHook* call_hook_;
   CompletionQueue* cq_;
   grpc_call* call_;
-  int max_message_size_;
+  int max_receive_message_size_;
 };
 
 }  // namespace grpc

include/grpc++/impl/codegen/method_handler_impl.h

@@ -53,7 +53,7 @@ class RpcMethodHandler : public MethodHandler {
   void RunHandler(const HandlerParameter& param) GRPC_FINAL {
     RequestType req;
     Status status = SerializationTraits<RequestType>::Deserialize(
-        param.request, &req, param.max_message_size);
+        param.request, &req, param.max_receive_message_size);
     ResponseType rsp;
     if (status.ok()) {
       status = func_(service_, param.server_context, &req, &rsp);
@@ -139,7 +139,7 @@ class ServerStreamingHandler : public MethodHandler {
   void RunHandler(const HandlerParameter& param) GRPC_FINAL {
     RequestType req;
     Status status = SerializationTraits<RequestType>::Deserialize(
-        param.request, &req, param.max_message_size);
+        param.request, &req, param.max_receive_message_size);
 
     if (status.ok()) {
       ServerWriter<ResponseType> writer(param.call, param.server_context);

include/grpc++/impl/codegen/proto_utils.h

@@ -204,7 +204,7 @@ class SerializationTraits<T, typename std::enable_if<std::is_base_of<
 
   static Status Deserialize(grpc_byte_buffer* buffer,
                             grpc::protobuf::Message* msg,
-                            int max_message_size) {
+                            int max_receive_message_size) {
     if (buffer == nullptr) {
       return Status(StatusCode::INTERNAL, "No payload");
     }
@@ -215,8 +215,9 @@ class SerializationTraits<T, typename std::enable_if<std::is_base_of<
         return reader.status();
       }
       ::grpc::protobuf::io::CodedInputStream decoder(&reader);
-      if (max_message_size > 0) {
-        decoder.SetTotalBytesLimit(max_message_size, max_message_size);
+      if (max_receive_message_size > 0) {
+        decoder.SetTotalBytesLimit(max_receive_message_size,
+                                   max_receive_message_size);
       }
       if (!msg->ParseFromCodedStream(&decoder)) {
         result = Status(StatusCode::INTERNAL, msg->InitializationErrorString());

include/grpc++/impl/codegen/rpc_service_method.h

@@ -62,12 +62,12 @@ class MethodHandler {
         : call(c),
           server_context(context),
           request(req),
-          max_message_size(max_size) {}
+          max_receive_message_size(max_size) {}
     Call* call;
     ServerContext* server_context;
     // Handler required to grpc_byte_buffer_destroy this
     grpc_byte_buffer* request;
-    int max_message_size;
+    int max_receive_message_size;
   };
   virtual void RunHandler(const HandlerParameter& param) = 0;
 };

include/grpc++/impl/codegen/serialization_traits.h

@@ -43,10 +43,10 @@ namespace grpc {
 /// functions:
 ///   static Status Serialize(const Message& msg,
 ///                           grpc_byte_buffer** buffer,
-//                            bool* own_buffer);
+///                           bool* own_buffer);
 ///   static Status Deserialize(grpc_byte_buffer* buffer,
 ///                             Message* msg,
-///                             int max_message_size);
+///                             int max_receive_message_size);
 ///
 /// Serialize is required to convert message to a grpc_byte_buffer, and
 /// to store a pointer to that byte buffer at *buffer. *own_buffer should
@@ -54,8 +54,8 @@ namespace grpc {
 /// ownership is retained elsewhere.
 ///
 /// Deserialize is required to convert buffer into the message stored at
-/// msg. max_message_size is passed in as a bound on the maximum number of
-/// message bytes Deserialize should accept.
+/// msg. max_receive_message_size is passed in as a bound on the maximum
+/// number of message bytes Deserialize should accept.
 ///
 /// Both functions return a Status, allowing them to explain what went
 /// wrong if required.

include/grpc++/impl/codegen/server_interface.h

@@ -134,7 +134,7 @@ class ServerInterface : public CallHook {
 
   virtual void ShutdownInternal(gpr_timespec deadline) = 0;
 
-  virtual int max_message_size() const = 0;
+  virtual int max_receive_message_size() const = 0;
 
   virtual grpc_server* server() = 0;
 
@@ -205,8 +205,8 @@ class ServerInterface : public CallHook {
     bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE {
       bool serialization_status =
           *status && payload_ &&
-          SerializationTraits<Message>::Deserialize(payload_, request_,
-                                                    server_->max_message_size())
+          SerializationTraits<Message>::Deserialize(
+              payload_, request_, server_->max_receive_message_size())
               .ok();
       bool ret = RegisteredAsyncRequest::FinalizeResult(tag, status);
       *status = serialization_status && *status;

src/core/lib/iomgr/workqueue_posix.h → include/grpc++/impl/codegen/status_helper.h

@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015, Google Inc.
+ * Copyright 2016, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -31,28 +31,17 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_IOMGR_WORKQUEUE_POSIX_H
-#define GRPC_CORE_LIB_IOMGR_WORKQUEUE_POSIX_H
+#ifndef GRPCXX_IMPL_CODEGEN_STATUS_HELPER_H
+#define GRPCXX_IMPL_CODEGEN_STATUS_HELPER_H
 
-#include "src/core/lib/iomgr/wakeup_fd_posix.h"
+#include <grpc++/impl/codegen/status.h>
 
-struct grpc_fd;
+namespace grpc {
 
-struct grpc_workqueue {
-  gpr_refcount refs;
+inline StatusCode GetCanonicalCode(const Status& status) {
+  return status.error_code();
+}
 
-  gpr_mu mu;
-  grpc_closure_list closure_list;
+}  // namespace grpc
 
-  grpc_wakeup_fd wakeup_fd;
-  struct grpc_fd *wakeup_read_fd;
-
-  grpc_closure read_closure;
-};
-
-/** Create a work queue. Returns an error if creation fails. If creation
-    succeeds, sets *workqueue to point to it. */
-grpc_error *grpc_workqueue_create(grpc_exec_ctx *exec_ctx,
-                                  grpc_workqueue **workqueue);
-
-#endif /* GRPC_CORE_LIB_IOMGR_WORKQUEUE_POSIX_H */
+#endif  // GRPCXX_IMPL_CODEGEN_STATUS_HELPER_H

include/grpc++/impl/codegen/sync_stream.h

@@ -160,7 +160,7 @@ class ClientReader GRPC_FINAL : public ClientReaderInterface<R> {
   }
 
   bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
-    *sz = call_.max_message_size();
+    *sz = call_.max_receive_message_size();
     return true;
   }
 
@@ -310,7 +310,7 @@ class ClientReaderWriter GRPC_FINAL : public ClientReaderWriterInterface<W, R> {
   }
 
   bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
-    *sz = call_.max_message_size();
+    *sz = call_.max_receive_message_size();
     return true;
   }
 
@@ -382,7 +382,7 @@ class ServerReader GRPC_FINAL : public ServerReaderInterface<R> {
   }
 
   bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
-    *sz = call_->max_message_size();
+    *sz = call_->max_receive_message_size();
     return true;
   }
 
@@ -474,7 +474,7 @@ class ServerReaderWriterBody GRPC_FINAL {
   }
 
   bool NextMessageSize(uint32_t* sz) {
-    *sz = call_->max_message_size();
+    *sz = call_->max_receive_message_size();
     return true;
   }
 

include/grpc++/impl/codegen/thrift_utils.h

@@ -64,7 +64,7 @@ class SerializationTraits<T, typename std::enable_if<std::is_base_of<
   }
 
   static Status Deserialize(grpc_byte_buffer* buffer, T* msg,
-                            int max_message_size) {
+                            int max_receive_message_size) {
     if (!buffer) {
       return Status(StatusCode::INTERNAL, "No payload");
     }

include/grpc++/server.h

@@ -116,10 +116,10 @@ class Server GRPC_FINAL : public ServerInterface, private GrpcLibraryCodegen {
   ///
   /// \param thread_pool The threadpool instance to use for call processing.
   /// \param thread_pool_owned Does the server own the \a thread_pool instance?
-  /// \param max_message_size Maximum message length that the channel can
-  /// receive.
+  /// \param max_receive_message_size Maximum message length that the channel
+  /// can receive.
   Server(ThreadPoolInterface* thread_pool, bool thread_pool_owned,
-         int max_message_size, ChannelArguments* args);
+         int max_receive_message_size, 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.
@@ -164,13 +164,15 @@ class Server GRPC_FINAL : public ServerInterface, private GrpcLibraryCodegen {
 
   void ShutdownInternal(gpr_timespec deadline) GRPC_OVERRIDE;
 
-  int max_message_size() const GRPC_OVERRIDE { return max_message_size_; };
+  int max_receive_message_size() const GRPC_OVERRIDE {
+    return max_receive_message_size_;
+  };
 
   grpc_server* server() GRPC_OVERRIDE { return server_; };
 
   ServerInitializer* initializer();
 
-  const int max_message_size_;
+  const int max_receive_message_size_;
 
   // Completion queue.
   CompletionQueue cq_;

include/grpc++/server_builder.h

@@ -78,12 +78,23 @@ class ServerBuilder {
   /// Only matches requests with :authority \a host
   ServerBuilder& RegisterService(const grpc::string& host, Service* service);
 
-  /// Set max message size in bytes.
-  ServerBuilder& SetMaxMessageSize(int max_message_size) {
-    max_message_size_ = max_message_size;
+  /// Set max receive message size in bytes.
+  ServerBuilder& SetMaxReceiveMessageSize(int max_receive_message_size) {
+    max_receive_message_size_ = max_receive_message_size;
+    return *this;
+  }
+
+  /// Set max send message size in bytes.
+  ServerBuilder& SetMaxSendMessageSize(int max_send_message_size) {
+    max_send_message_size_ = max_send_message_size;
     return *this;
   }
 
+  /// \deprecated For backward compatibility.
+  ServerBuilder& SetMaxMessageSize(int max_message_size) {
+    return SetMaxReceiveMessageSize(max_message_size);
+  }
+
   /// Set the support status for compression algorithms. All algorithms are
   /// enabled by default.
   ///
@@ -168,7 +179,8 @@ class ServerBuilder {
     Service* service;
   };
 
-  int max_message_size_;
+  int max_receive_message_size_;
+  int max_send_message_size_;
   std::vector<std::unique_ptr<ServerBuilderOption>> options_;
   std::vector<std::unique_ptr<NamedService>> services_;
   std::vector<Port> ports_;

include/grpc++/support/byte_buffer.h

@@ -96,7 +96,7 @@ template <>
 class SerializationTraits<ByteBuffer, void> {
  public:
   static Status Deserialize(grpc_byte_buffer* byte_buffer, ByteBuffer* dest,
-                            int max_message_size) {
+                            int max_receive_message_size) {
     dest->set_buffer(byte_buffer);
     return Status::OK;
   }

include/grpc/impl/codegen/atm.h

@@ -75,6 +75,9 @@
    int gpr_atm_no_barrier_cas(gpr_atm *p, gpr_atm o, gpr_atm n);
    int gpr_atm_acq_cas(gpr_atm *p, gpr_atm o, gpr_atm n);
    int gpr_atm_rel_cas(gpr_atm *p, gpr_atm o, gpr_atm n);
+
+   // Atomically, set *p=n and return the old value of *p
+   gpr_atm gpr_atm_full_xchg(gpr_atm *p, gpr_atm n);
 */
 
 #include <grpc/impl/codegen/port_platform.h>

include/grpc/impl/codegen/atm_gcc_atomic.h

@@ -69,4 +69,6 @@ static __inline int gpr_atm_rel_cas(gpr_atm *p, gpr_atm o, gpr_atm n) {
                                      __ATOMIC_RELAXED);
 }
 
+#define gpr_atm_full_xchg(p, n) __atomic_exchange_n((p), (n), __ATOMIC_ACQ_REL)
+
 #endif /* GRPC_IMPL_CODEGEN_ATM_GCC_ATOMIC_H */

include/grpc/impl/codegen/atm_gcc_sync.h

@@ -84,4 +84,12 @@ static __inline void gpr_atm_no_barrier_store(gpr_atm *p, gpr_atm value) {
 #define gpr_atm_acq_cas(p, o, n) (__sync_bool_compare_and_swap((p), (o), (n)))
 #define gpr_atm_rel_cas(p, o, n) gpr_atm_acq_cas((p), (o), (n))
 
+static __inline gpr_atm gpr_atm_full_xchg(gpr_atm *p, gpr_atm n) {
+  gpr_atm cur;
+  do {
+    cur = gpr_atm_acq_load(p);
+  } while (!gpr_atm_rel_cas(p, cur, n));
+  return cur;
+}
+
 #endif /* GRPC_IMPL_CODEGEN_ATM_GCC_SYNC_H */

include/grpc/impl/codegen/atm_windows.h

@@ -122,4 +122,8 @@ static __inline gpr_atm gpr_atm_full_fetch_add(gpr_atm *p, gpr_atm delta) {
   return old;
 }
 
+static __inline gpr_atm gpr_atm_full_xchg(gpr_atm *p, gpr_atm n) {
+  return (gpr_atm)InterlockedExchangePointer((PVOID *)p, (PVOID)n);
+}
+
 #endif /* GRPC_IMPL_CODEGEN_ATM_WINDOWS_H */

include/grpc/impl/codegen/grpc_types.h

@@ -149,7 +149,11 @@ typedef struct {
     connection. Int valued. */
 #define GRPC_ARG_MAX_CONCURRENT_STREAMS "grpc.max_concurrent_streams"
 /** Maximum message length that the channel can receive. Int valued, bytes. */
-#define GRPC_ARG_MAX_MESSAGE_LENGTH "grpc.max_message_length"
+#define GRPC_ARG_MAX_RECEIVE_MESSAGE_LENGTH "grpc.max_receive_message_length"
+/** \deprecated For backward compatibility. */
+#define GRPC_ARG_MAX_MESSAGE_LENGTH GRPC_ARG_MAX_RECEIVE_MESSAGE_LENGTH
+/** Maximum message length that the channel can send. Int valued, bytes. */
+#define GRPC_ARG_MAX_SEND_MESSAGE_LENGTH "grpc.max_send_message_length"
 /** Initial sequence number for http2 transports. Int valued. */
 #define GRPC_ARG_HTTP2_INITIAL_SEQUENCE_NUMBER \
   "grpc.http2.initial_sequence_number"

package.xml

@@ -94,6 +94,7 @@
     <file baseinstalldir="/" name="src/core/lib/support/backoff.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/block_annotate.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/env.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/support/mpscq.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/murmur_hash.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/percent_encoding.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/stack_lockfree.h" role="src" />
@@ -122,6 +123,7 @@
     <file baseinstalldir="/" name="src/core/lib/support/log_linux.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/log_posix.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/log_windows.c" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/support/mpscq.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/murmur_hash.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/percent_encoding.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/slice.c" role="src" />
@@ -183,6 +185,7 @@
     <file baseinstalldir="/" name="src/core/lib/channel/handshaker.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/channel/http_client_filter.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/channel/http_server_filter.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/channel/message_size_filter.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/compression/algorithm_metadata.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/compression/message_compress.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/debug/trace.h" role="src" />
@@ -190,6 +193,7 @@
     <file baseinstalldir="/" name="src/core/lib/http/httpcli.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/http/parser.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/closure.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/iomgr/combiner.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/endpoint.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/endpoint_pair.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/error.h" role="src" />
@@ -229,7 +233,6 @@
     <file baseinstalldir="/" name="src/core/lib/iomgr/wakeup_fd_pipe.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/wakeup_fd_posix.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/workqueue.h" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/iomgr/workqueue_posix.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/workqueue_windows.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/json/json.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/json/json_common.h" role="src" />
@@ -333,6 +336,7 @@
     <file baseinstalldir="/" name="src/core/ext/census/mlog.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/census/resource.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/census/rpc_metric_id.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/census/trace_context.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/surface/init.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/channel/channel_args.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/channel/channel_stack.c" role="src" />
@@ -342,6 +346,7 @@
     <file baseinstalldir="/" name="src/core/lib/channel/handshaker.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/channel/http_client_filter.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/channel/http_server_filter.c" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/channel/message_size_filter.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/compression/compression.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/compression/message_compress.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/debug/trace.c" role="src" />
@@ -349,6 +354,7 @@
     <file baseinstalldir="/" name="src/core/lib/http/httpcli.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/http/parser.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/closure.c" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/iomgr/combiner.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/endpoint.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/endpoint_pair_posix.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/endpoint_pair_windows.c" role="src" />
@@ -391,7 +397,6 @@
     <file baseinstalldir="/" name="src/core/lib/iomgr/wakeup_fd_nospecial.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/wakeup_fd_pipe.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/wakeup_fd_posix.c" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/iomgr/workqueue_posix.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/iomgr/workqueue_windows.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/json/json.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/json/json_reader.c" role="src" />
@@ -521,6 +526,7 @@
     <file baseinstalldir="/" name="src/core/ext/census/operation.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/census/placeholders.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/census/resource.c" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/census/trace_context.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/census/tracing.c" role="src" />
     <file baseinstalldir="/" name="src/core/plugin_registry/grpc_plugin_registry.c" role="src" />
     <file baseinstalldir="/" name="third_party/boringssl/crypto/aes/internal.h" role="src" />

src/core/ext/census/trace_context.c

@@ -0,0 +1,86 @@
+/*
+ *
+ * Copyright 2016, 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/ext/census/trace_context.h"
+
+#include <grpc/census.h>
+#include <grpc/support/log.h>
+#include <stdbool.h>
+
+#include "third_party/nanopb/pb_decode.h"
+#include "third_party/nanopb/pb_encode.h"
+
+// This function assumes the TraceContext is valid.
+size_t encode_trace_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
+                            const size_t buf_size) {
+  // Create a stream that will write to our buffer.
+  pb_ostream_t stream = pb_ostream_from_buffer(buffer, buf_size);
+
+  // encode message
+  bool status = pb_encode(&stream, google_trace_TraceContext_fields, ctxt);
+
+  if (!status) {
+    gpr_log(GPR_DEBUG, "TraceContext encoding failed: %s",
+            PB_GET_ERROR(&stream));
+    return 0;
+  }
+
+  return stream.bytes_written;
+}
+
+bool decode_trace_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
+                          const size_t nbytes) {
+  // Create a stream that reads nbytes from the buffer.
+  pb_istream_t stream = pb_istream_from_buffer(buffer, nbytes);
+
+  // decode message
+  bool status = pb_decode(&stream, google_trace_TraceContext_fields, ctxt);
+
+  if (!status) {
+    gpr_log(GPR_DEBUG, "TraceContext decoding failed: %s",
+            PB_GET_ERROR(&stream));
+    return false;
+  }
+
+  // check fields
+  if (!ctxt->has_trace_id) {
+    gpr_log(GPR_DEBUG, "Invalid TraceContext: missing trace_id");
+    return false;
+  }
+  if (!ctxt->has_span_id) {
+    gpr_log(GPR_DEBUG, "Invalid TraceContext: missing span_id");
+    return false;
+  }
+
+  return true;
+}

src/core/ext/census/trace_context.h

@@ -0,0 +1,68 @@
+/*
+ *
+ * Copyright 2016, 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.
+ *
+ */
+
+/* Functions for manipulating trace contexts as defined in
+   src/proto/census/trace.proto */
+#ifndef GRPC_CORE_EXT_CENSUS_TRACE_CONTEXT_H
+#define GRPC_CORE_EXT_CENSUS_TRACE_CONTEXT_H
+
+#include "src/core/ext/census/gen/trace_context.pb.h"
+
+/* Maximum number of bytes required to encode a TraceContext (31)
+1 byte for trace_id field
+1 byte for trace_id length
+1 byte for trace_id.hi field
+8 bytes for trace_id.hi (uint64_t)
+1 byte for trace_id.lo field
+8 bytes for trace_id.lo (uint64_t)
+1 byte for span_id field
+8 bytes for span_id (uint64_t)
+1 byte for is_sampled field
+1 byte for is_sampled (bool) */
+#define TRACE_MAX_CONTEXT_SIZE 31
+
+/* Encode a trace context (ctxt) into proto format to the buffer provided.  The
+size of buffer must be at least TRACE_MAX_CONTEXT_SIZE.  On success, returns the
+number of bytes successfully encoded into buffer.  On failure, returns 0. */
+size_t encode_trace_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
+                            const size_t buf_size);
+
+/* Decode a proto-encoded TraceContext from the provided buffer into the
+TraceContext structure (ctxt).  The function expects to be supplied the number
+of bytes to be read from buffer (nbytes).  This function will also validate that
+the TraceContext has a span_id and a trace_id, and will return false if either
+of these do not exist. On success, returns true and false otherwise. */
+bool decode_trace_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
+                          const size_t nbytes);
+
+#endif

src/core/ext/census/tracing.c

@@ -31,15 +31,19 @@
  *
  */
 
+//#include "src/core/ext/census/tracing.h"
+
 #include <grpc/census.h>
 
 /* TODO(aveitch): These are all placeholder implementations. */
 
-int census_trace_mask(const census_context *context) {
-  return CENSUS_TRACE_MASK_NONE;
-}
+// int census_trace_mask(const census_context *context) {
+//   return CENSUS_TRACE_MASK_NONE;
+// }
+
+// void census_set_trace_mask(int trace_mask) {}
 
-void census_set_trace_mask(int trace_mask) {}
+// void census_trace_print(census_context *context, uint32_t type,
+//                         const char *buffer, size_t n) {}
 
-void census_trace_print(census_context *context, uint32_t type,
-                        const char *buffer, size_t n) {}
+// void SetTracerParams(const Params& params);

src/core/ext/client_config/client_channel.c

@@ -42,6 +42,7 @@
 #include <grpc/support/sync.h>
 #include <grpc/support/useful.h>
 
+#include "src/core/ext/client_config/lb_policy_registry.h"
 #include "src/core/ext/client_config/subchannel.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
@@ -63,6 +64,8 @@ typedef struct client_channel_channel_data {
   grpc_resolver *resolver;
   /** have we started resolving this channel */
   bool started_resolving;
+  /** client channel factory */
+  grpc_client_channel_factory *client_channel_factory;
 
   /** mutex protecting client configuration, including all
       variables below in this data structure */
@@ -173,20 +176,26 @@ static void on_resolver_result_changed(grpc_exec_ctx *exec_ctx, void *arg,
   grpc_error *state_error = GRPC_ERROR_CREATE("No load balancing policy");
 
   if (chand->resolver_result != NULL) {
-    lb_policy = grpc_resolver_result_get_lb_policy(chand->resolver_result);
+    grpc_lb_policy_args lb_policy_args;
+    lb_policy_args.addresses =
+        grpc_resolver_result_get_addresses(chand->resolver_result);
+    lb_policy_args.additional_args =
+        grpc_resolver_result_get_lb_policy_args(chand->resolver_result);
+    lb_policy_args.client_channel_factory = chand->client_channel_factory;
+    lb_policy = grpc_lb_policy_create(
+        exec_ctx,
+        grpc_resolver_result_get_lb_policy_name(chand->resolver_result),
+        &lb_policy_args);
     if (lb_policy != NULL) {
-      GRPC_LB_POLICY_REF(lb_policy, "channel");
       GRPC_LB_POLICY_REF(lb_policy, "config_change");
       GRPC_ERROR_UNREF(state_error);
       state =
           grpc_lb_policy_check_connectivity(exec_ctx, lb_policy, &state_error);
     }
-
     grpc_resolver_result_unref(exec_ctx, chand->resolver_result);
+    chand->resolver_result = NULL;
   }
 
-  chand->resolver_result = NULL;
-
   if (lb_policy != NULL) {
     grpc_pollset_set_add_pollset_set(exec_ctx, lb_policy->interested_parties,
                                      chand->interested_parties);
@@ -346,6 +355,9 @@ static void cc_destroy_channel_elem(grpc_exec_ctx *exec_ctx,
     grpc_resolver_shutdown(exec_ctx, chand->resolver);
     GRPC_RESOLVER_UNREF(exec_ctx, chand->resolver, "channel");
   }
+  if (chand->client_channel_factory != NULL) {
+    grpc_client_channel_factory_unref(exec_ctx, chand->client_channel_factory);
+  }
   if (chand->lb_policy != NULL) {
     grpc_pollset_set_del_pollset_set(exec_ctx,
                                      chand->lb_policy->interested_parties,
@@ -387,13 +399,15 @@ typedef struct client_channel_call_data {
   grpc_connected_subchannel *connected_subchannel;
   grpc_polling_entity *pollent;
 
-  grpc_transport_stream_op *waiting_ops;
+  grpc_transport_stream_op **waiting_ops;
   size_t waiting_ops_count;
   size_t waiting_ops_capacity;
 
   grpc_closure next_step;
 
   grpc_call_stack *owning_call;
+
+  grpc_linked_mdelem lb_token_mdelem;
 } call_data;
 
 static void add_waiting_locked(call_data *calld, grpc_transport_stream_op *op) {
@@ -404,7 +418,7 @@ static void add_waiting_locked(call_data *calld, grpc_transport_stream_op *op) {
         gpr_realloc(calld->waiting_ops,
                     calld->waiting_ops_capacity * sizeof(*calld->waiting_ops));
   }
-  calld->waiting_ops[calld->waiting_ops_count++] = *op;
+  calld->waiting_ops[calld->waiting_ops_count++] = op;
   GPR_TIMER_END("add_waiting_locked", 0);
 }
 
@@ -413,14 +427,14 @@ static void fail_locked(grpc_exec_ctx *exec_ctx, call_data *calld,
   size_t i;
   for (i = 0; i < calld->waiting_ops_count; i++) {
     grpc_transport_stream_op_finish_with_failure(
-        exec_ctx, &calld->waiting_ops[i], GRPC_ERROR_REF(error));
+        exec_ctx, calld->waiting_ops[i], GRPC_ERROR_REF(error));
   }
   calld->waiting_ops_count = 0;
   GRPC_ERROR_UNREF(error);
 }
 
 typedef struct {
-  grpc_transport_stream_op *ops;
+  grpc_transport_stream_op **ops;
   size_t nops;
   grpc_subchannel_call *call;
 } retry_ops_args;
@@ -429,7 +443,7 @@ static void retry_ops(grpc_exec_ctx *exec_ctx, void *args, grpc_error *error) {
   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_process_op(exec_ctx, a->call, a->ops[i]);
   }
   GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, a->call, "retry_ops");
   gpr_free(a->ops);
@@ -437,6 +451,10 @@ static void retry_ops(grpc_exec_ctx *exec_ctx, void *args, grpc_error *error) {
 }
 
 static void retry_waiting_locked(grpc_exec_ctx *exec_ctx, call_data *calld) {
+  if (calld->waiting_ops_count == 0) {
+    return;
+  }
+
   retry_ops_args *a = gpr_malloc(sizeof(*a));
   a->ops = calld->waiting_ops;
   a->nops = calld->waiting_ops_count;
@@ -566,9 +584,11 @@ static bool pick_subchannel(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
     int r;
     GRPC_LB_POLICY_REF(lb_policy, "pick_subchannel");
     gpr_mu_unlock(&chand->mu);
-    r = grpc_lb_policy_pick(exec_ctx, lb_policy, calld->pollent,
-                            initial_metadata, initial_metadata_flags,
-                            connected_subchannel, on_ready);
+    const grpc_lb_policy_pick_args inputs = {calld->pollent, initial_metadata,
+                                             initial_metadata_flags,
+                                             &calld->lb_token_mdelem};
+    r = grpc_lb_policy_pick(exec_ctx, lb_policy, &inputs, connected_subchannel,
+                            NULL, on_ready);
     GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "pick_subchannel");
     GPR_TIMER_END("pick_subchannel", 0);
     return r;
@@ -759,10 +779,12 @@ const grpc_channel_filter grpc_client_channel_filter = {
     "client-channel",
 };
 
-void grpc_client_channel_set_resolver(grpc_exec_ctx *exec_ctx,
-                                      grpc_channel_stack *channel_stack,
-                                      grpc_resolver *resolver) {
+void grpc_client_channel_finish_initialization(
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack *channel_stack,
+    grpc_resolver *resolver,
+    grpc_client_channel_factory *client_channel_factory) {
   /* post construction initialization: set the transport setup pointer */
+  GPR_ASSERT(client_channel_factory != NULL);
   grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
   channel_data *chand = elem->channel_data;
   gpr_mu_lock(&chand->mu);
@@ -776,6 +798,8 @@ void grpc_client_channel_set_resolver(grpc_exec_ctx *exec_ctx,
     grpc_resolver_next(exec_ctx, resolver, &chand->resolver_result,
                        &chand->on_resolver_result_changed);
   }
+  chand->client_channel_factory = client_channel_factory;
+  grpc_client_channel_factory_ref(client_channel_factory);
   gpr_mu_unlock(&chand->mu);
 }
 

src/core/ext/client_config/client_channel.h

@@ -34,6 +34,7 @@
 #ifndef GRPC_CORE_EXT_CLIENT_CONFIG_CLIENT_CHANNEL_H
 #define GRPC_CORE_EXT_CLIENT_CONFIG_CLIENT_CHANNEL_H
 
+#include "src/core/ext/client_config/client_channel_factory.h"
 #include "src/core/ext/client_config/resolver.h"
 #include "src/core/lib/channel/channel_stack.h"
 
@@ -46,12 +47,12 @@
 
 extern const grpc_channel_filter grpc_client_channel_filter;
 
-/* post-construction initializer to let the client channel know which
-   transport setup it should cancel upon destruction, or initiate when it needs
-   a connection */
-void grpc_client_channel_set_resolver(grpc_exec_ctx *exec_ctx,
-                                      grpc_channel_stack *channel_stack,
-                                      grpc_resolver *resolver);
+/* Post-construction initializer to give the client channel its resolver
+   and factory. */
+void grpc_client_channel_finish_initialization(
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack *channel_stack,
+    grpc_resolver *resolver,
+    grpc_client_channel_factory *client_channel_factory);
 
 grpc_connectivity_state grpc_client_channel_check_connectivity_state(
     grpc_exec_ctx *exec_ctx, grpc_channel_element *elem, int try_to_connect);

src/core/ext/client_config/lb_policy.c

@@ -100,13 +100,11 @@ void grpc_lb_policy_weak_unref(grpc_exec_ctx *exec_ctx,
 }
 
 int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                        grpc_polling_entity *pollent,
-                        grpc_metadata_batch *initial_metadata,
-                        uint32_t initial_metadata_flags,
-                        grpc_connected_subchannel **target,
+                        const grpc_lb_policy_pick_args *pick_args,
+                        grpc_connected_subchannel **target, void **user_data,
                         grpc_closure *on_complete) {
-  return policy->vtable->pick(exec_ctx, policy, pollent, initial_metadata,
-                              initial_metadata_flags, target, on_complete);
+  return policy->vtable->pick(exec_ctx, policy, pick_args, target, user_data,
+                              on_complete);
 }
 
 void grpc_lb_policy_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,

src/core/ext/client_config/lb_policy.h

@@ -53,23 +53,38 @@ struct grpc_lb_policy {
   grpc_pollset_set *interested_parties;
 };
 
+/** Extra arguments for an LB pick */
+typedef struct grpc_lb_policy_pick_args {
+  /** Parties interested in the pick's progress */
+  grpc_polling_entity *pollent;
+  /** Initial metadata associated with the picking call. */
+  grpc_metadata_batch *initial_metadata;
+  /** See \a GRPC_INITIAL_METADATA_* in grpc_types.h */
+  uint32_t initial_metadata_flags;
+  /** Storage for LB token in \a initial_metadata, or NULL if not used */
+  grpc_linked_mdelem *lb_token_mdelem_storage;
+} grpc_lb_policy_pick_args;
+
 struct grpc_lb_policy_vtable {
   void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
-
   void (*shutdown)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
 
-  /** implement grpc_lb_policy_pick */
+  /** \see grpc_lb_policy_pick */
   int (*pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-              grpc_polling_entity *pollent,
-              grpc_metadata_batch *initial_metadata,
-              uint32_t initial_metadata_flags,
-              grpc_connected_subchannel **target, grpc_closure *on_complete);
+              const grpc_lb_policy_pick_args *pick_args,
+              grpc_connected_subchannel **target, void **user_data,
+              grpc_closure *on_complete);
+
+  /** \see grpc_lb_policy_cancel_pick */
   void (*cancel_pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                       grpc_connected_subchannel **target);
+
+  /** \see grpc_lb_policy_cancel_picks */
   void (*cancel_picks)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                        uint32_t initial_metadata_flags_mask,
                        uint32_t initial_metadata_flags_eq);
 
+  /** \see grpc_lb_policy_ping_one */
   void (*ping_one)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                    grpc_closure *closure);
 
@@ -83,8 +98,7 @@ struct grpc_lb_policy_vtable {
 
   /** call notify when the connectivity state of a channel changes from *state.
       Updates *state with the new state of the policy. Calling with a NULL \a
-      state cancels the subscription.
-      */
+      state cancels the subscription.  */
   void (*notify_on_state_change)(grpc_exec_ctx *exec_ctx,
                                  grpc_lb_policy *policy,
                                  grpc_connectivity_state *state,
@@ -124,26 +138,34 @@ void grpc_lb_policy_weak_unref(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
 void grpc_lb_policy_init(grpc_lb_policy *policy,
                          const grpc_lb_policy_vtable *vtable);
 
-/** Given initial metadata in \a initial_metadata, find an appropriate
-    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 pollent. */
+/** Find an appropriate target for this call, based on \a pick_args.
+    Picking can be synchronous or asynchronous. In the synchronous case, when a
+    pick is readily available, it'll be returned in \a target and a non-zero
+    value will be returned.
+    In the asynchronous case, zero is returned and \a on_complete will be called
+    once \a target and \a user_data have been set. Any IO should be done under
+    \a pick_args->pollent. The opaque \a user_data output argument corresponds
+    to information that may need be propagated from the LB policy. It may be
+    NULL. Errors are signaled by receiving a NULL \a *target. */
 int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                        grpc_polling_entity *pollent,
-                        grpc_metadata_batch *initial_metadata,
-                        uint32_t initial_metadata_flags,
-                        grpc_connected_subchannel **target,
+                        const grpc_lb_policy_pick_args *pick_args,
+                        grpc_connected_subchannel **target, void **user_data,
                         grpc_closure *on_complete);
 
+/** Perform a connected subchannel ping (see \a grpc_connected_subchannel_ping)
+    against one of the connected subchannels managed by \a policy. */
 void grpc_lb_policy_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                              grpc_closure *closure);
 
+/** Cancel picks for \a target.
+    The \a on_complete callback of the pending picks will be invoked with \a
+    *target set to NULL. */
 void grpc_lb_policy_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                                 grpc_connected_subchannel **target);
 
-/** Cancel all pending picks which have:
-    (initial_metadata_flags & initial_metadata_flags_mask) ==
-         initial_metadata_flags_eq */
+/** Cancel all pending picks for which their \a initial_metadata_flags (as given
+    in the call to \a grpc_lb_policy_pick) matches \a initial_metadata_flags_eq
+    when AND'd with \a initial_metadata_flags_mask */
 void grpc_lb_policy_cancel_picks(grpc_exec_ctx *exec_ctx,
                                  grpc_lb_policy *policy,
                                  uint32_t initial_metadata_flags_mask,

src/core/ext/client_config/lb_policy_factory.c

@@ -31,8 +31,66 @@
  *
  */
 
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+
 #include "src/core/ext/client_config/lb_policy_factory.h"
 
+grpc_lb_addresses* grpc_lb_addresses_create(size_t num_addresses) {
+  grpc_lb_addresses* addresses = gpr_malloc(sizeof(grpc_lb_addresses));
+  addresses->num_addresses = num_addresses;
+  const size_t addresses_size = sizeof(grpc_lb_address) * num_addresses;
+  addresses->addresses = gpr_malloc(addresses_size);
+  memset(addresses->addresses, 0, addresses_size);
+  return addresses;
+}
+
+grpc_lb_addresses* grpc_lb_addresses_copy(grpc_lb_addresses* addresses,
+                                          void* (*user_data_copy)(void*)) {
+  grpc_lb_addresses* new_addresses =
+      grpc_lb_addresses_create(addresses->num_addresses);
+  memcpy(new_addresses->addresses, addresses->addresses,
+         sizeof(grpc_lb_address) * addresses->num_addresses);
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (new_addresses->addresses[i].balancer_name != NULL) {
+      new_addresses->addresses[i].balancer_name =
+          gpr_strdup(new_addresses->addresses[i].balancer_name);
+    }
+    if (user_data_copy != NULL) {
+      new_addresses->addresses[i].user_data =
+          user_data_copy(new_addresses->addresses[i].user_data);
+    }
+  }
+  return new_addresses;
+}
+
+void grpc_lb_addresses_set_address(grpc_lb_addresses* addresses, size_t index,
+                                   void* address, size_t address_len,
+                                   bool is_balancer, char* balancer_name,
+                                   void* user_data) {
+  GPR_ASSERT(index < addresses->num_addresses);
+  grpc_lb_address* target = &addresses->addresses[index];
+  memcpy(target->address.addr, address, address_len);
+  target->address.len = address_len;
+  target->is_balancer = is_balancer;
+  target->balancer_name = balancer_name;
+  target->user_data = user_data;
+}
+
+void grpc_lb_addresses_destroy(grpc_lb_addresses* addresses,
+                               void (*user_data_destroy)(void*)) {
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    gpr_free(addresses->addresses[i].balancer_name);
+    if (user_data_destroy != NULL) {
+      user_data_destroy(addresses->addresses[i].user_data);
+    }
+  }
+  gpr_free(addresses->addresses);
+  gpr_free(addresses);
+}
+
 void grpc_lb_policy_factory_ref(grpc_lb_policy_factory* factory) {
   factory->vtable->ref(factory);
 }

src/core/ext/client_config/lb_policy_factory.h

@@ -36,9 +36,9 @@
 
 #include "src/core/ext/client_config/client_channel_factory.h"
 #include "src/core/ext/client_config/lb_policy.h"
-#include "src/core/lib/iomgr/resolve_address.h"
 
 #include "src/core/lib/iomgr/exec_ctx.h"
+#include "src/core/lib/iomgr/resolve_address.h"
 
 typedef struct grpc_lb_policy_factory grpc_lb_policy_factory;
 typedef struct grpc_lb_policy_factory_vtable grpc_lb_policy_factory_vtable;
@@ -47,9 +47,53 @@ struct grpc_lb_policy_factory {
   const grpc_lb_policy_factory_vtable *vtable;
 };
 
+/** A resolved address alongside any LB related information associated with it.
+ * \a user_data, if not NULL, contains opaque data meant to be consumed by the
+ * gRPC LB policy. Note that no all LB policies support \a user_data as input.
+ * Those who don't will simply ignore it and will correspondingly return NULL in
+ * their namesake pick() output argument. */
+typedef struct grpc_lb_address {
+  grpc_resolved_address address;
+  bool is_balancer;
+  char *balancer_name; /* For secure naming. */
+  void *user_data;
+} grpc_lb_address;
+
+typedef struct grpc_lb_addresses {
+  size_t num_addresses;
+  grpc_lb_address *addresses;
+} grpc_lb_addresses;
+
+/** Returns a grpc_addresses struct with enough space for
+ * \a num_addresses addresses. */
+grpc_lb_addresses *grpc_lb_addresses_create(size_t num_addresses);
+
+/** Creates a copy of \a addresses.  If \a user_data_copy is not NULL,
+ * it will be invoked to copy the \a user_data field of each address. */
+grpc_lb_addresses *grpc_lb_addresses_copy(grpc_lb_addresses *addresses,
+                                          void *(*user_data_copy)(void *));
+
+/** Sets the value of the address at index \a index of \a addresses.
+ * \a address is a socket address of length \a address_len.
+ * Takes ownership of \a balancer_name. */
+void grpc_lb_addresses_set_address(grpc_lb_addresses *addresses, size_t index,
+                                   void *address, size_t address_len,
+                                   bool is_balancer, char *balancer_name,
+                                   void *user_data);
+
+/** Destroys \a addresses.  If \a user_data_destroy is not NULL, it will
+ * be invoked to destroy the \a user_data field of each address. */
+void grpc_lb_addresses_destroy(grpc_lb_addresses *addresses,
+                               void (*user_data_destroy)(void *));
+
+/** Arguments passed to LB policies. */
+/* TODO(roth, ctiller): Consider replacing this struct with
+   grpc_channel_args.  See comment in resolver_result.h for details. */
 typedef struct grpc_lb_policy_args {
-  grpc_resolved_addresses *addresses;
+  grpc_lb_addresses *addresses;
   grpc_client_channel_factory *client_channel_factory;
+  /* Can be used to pass implementation-specific parameters to the LB policy. */
+  grpc_channel_args *additional_args;
 } grpc_lb_policy_args;
 
 struct grpc_lb_policy_factory_vtable {

src/core/ext/client_config/resolver_factory.h

@@ -47,10 +47,7 @@ struct grpc_resolver_factory {
   const grpc_resolver_factory_vtable *vtable;
 };
 
-typedef struct grpc_resolver_args {
-  grpc_uri *uri;
-  grpc_client_channel_factory *client_channel_factory;
-} grpc_resolver_args;
+typedef struct grpc_resolver_args { grpc_uri *uri; } grpc_resolver_args;
 
 struct grpc_resolver_factory_vtable {
   void (*ref)(grpc_resolver_factory *factory);

src/core/ext/client_config/resolver_registry.c

@@ -128,15 +128,13 @@ static grpc_resolver_factory *resolve_factory(const char *target,
   return factory;
 }
 
-grpc_resolver *grpc_resolver_create(
-    const char *target, grpc_client_channel_factory *client_channel_factory) {
+grpc_resolver *grpc_resolver_create(const char *target) {
   grpc_uri *uri = NULL;
   grpc_resolver_factory *factory = resolve_factory(target, &uri);
   grpc_resolver *resolver;
   grpc_resolver_args args;
   memset(&args, 0, sizeof(args));
   args.uri = uri;
-  args.client_channel_factory = client_channel_factory;
   resolver = grpc_resolver_factory_create_resolver(factory, &args);
   grpc_uri_destroy(uri);
   return resolver;

src/core/ext/client_config/resolver_registry.h

@@ -55,8 +55,7 @@ void grpc_register_resolver_type(grpc_resolver_factory *factory);
     If a resolver factory was found, use it to instantiate a resolver and
     return it.
     If a resolver factory was not found, return NULL. */
-grpc_resolver *grpc_resolver_create(
-    const char *target, grpc_client_channel_factory *client_channel_factory);
+grpc_resolver *grpc_resolver_create(const char *target);
 
 /** Find a resolver factory given a name and return an (owned-by-the-caller)
  *  reference to it */

src/core/ext/client_config/resolver_result.c

@@ -1,75 +1,87 @@
-/*
- *
- * 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.
- *
- */
+//
+// 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/ext/client_config/resolver_result.h"
 
 #include <string.h>
 
 #include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+
+#include "src/core/lib/channel/channel_args.h"
 
 struct grpc_resolver_result {
   gpr_refcount refs;
-  grpc_lb_policy *lb_policy;
+  grpc_lb_addresses* addresses;
+  char* lb_policy_name;
+  grpc_channel_args* lb_policy_args;
 };
 
-grpc_resolver_result *grpc_resolver_result_create() {
-  grpc_resolver_result *c = gpr_malloc(sizeof(*c));
-  memset(c, 0, sizeof(*c));
-  gpr_ref_init(&c->refs, 1);
-  return c;
+grpc_resolver_result* grpc_resolver_result_create(
+    grpc_lb_addresses* addresses, const char* lb_policy_name,
+    grpc_channel_args* lb_policy_args) {
+  grpc_resolver_result* result = gpr_malloc(sizeof(*result));
+  memset(result, 0, sizeof(*result));
+  gpr_ref_init(&result->refs, 1);
+  result->addresses = addresses;
+  result->lb_policy_name = gpr_strdup(lb_policy_name);
+  result->lb_policy_args = lb_policy_args;
+  return result;
 }
 
-void grpc_resolver_result_ref(grpc_resolver_result *c) { gpr_ref(&c->refs); }
+void grpc_resolver_result_ref(grpc_resolver_result* result) {
+  gpr_ref(&result->refs);
+}
 
-void grpc_resolver_result_unref(grpc_exec_ctx *exec_ctx,
-                                grpc_resolver_result *c) {
-  if (gpr_unref(&c->refs)) {
-    if (c->lb_policy != NULL) {
-      GRPC_LB_POLICY_UNREF(exec_ctx, c->lb_policy, "resolver_result");
-    }
-    gpr_free(c);
+void grpc_resolver_result_unref(grpc_exec_ctx* exec_ctx,
+                                grpc_resolver_result* result) {
+  if (gpr_unref(&result->refs)) {
+    grpc_lb_addresses_destroy(result->addresses, NULL /* user_data_destroy */);
+    gpr_free(result->lb_policy_name);
+    grpc_channel_args_destroy(result->lb_policy_args);
+    gpr_free(result);
   }
 }
 
-void grpc_resolver_result_set_lb_policy(grpc_resolver_result *c,
-                                        grpc_lb_policy *lb_policy) {
-  GPR_ASSERT(c->lb_policy == NULL);
-  if (lb_policy) {
-    GRPC_LB_POLICY_REF(lb_policy, "resolver_result");
-  }
-  c->lb_policy = lb_policy;
+grpc_lb_addresses* grpc_resolver_result_get_addresses(
+    grpc_resolver_result* result) {
+  return result->addresses;
+}
+
+const char* grpc_resolver_result_get_lb_policy_name(
+    grpc_resolver_result* result) {
+  return result->lb_policy_name;
 }
 
-grpc_lb_policy *grpc_resolver_result_get_lb_policy(grpc_resolver_result *c) {
-  return c->lb_policy;
+grpc_channel_args* grpc_resolver_result_get_lb_policy_args(
+    grpc_resolver_result* result) {
+  return result->lb_policy_args;
 }

src/core/ext/client_config/resolver_result.h

@@ -1,52 +1,71 @@
-/*
- *
- * 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.
- *
- */
+//
+// 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_CORE_EXT_CLIENT_CONFIG_RESOLVER_RESULT_H
 #define GRPC_CORE_EXT_CLIENT_CONFIG_RESOLVER_RESULT_H
 
-#include "src/core/ext/client_config/lb_policy.h"
+#include "src/core/ext/client_config/lb_policy_factory.h"
+#include "src/core/lib/iomgr/resolve_address.h"
 
-/** Results reported from a grpc_resolver. */
+// TODO(roth, ctiller): In the long term, we are considering replacing
+// the resolver_result data structure with grpc_channel_args.  The idea is
+// that the resolver will return a set of channel args that contains the
+// information that is currently in the resolver_result struct.  For
+// example, there will be specific args indicating the set of addresses
+// and the name of the LB policy to instantiate.  Note that if we did
+// this, we would probably want to change the data structure of
+// grpc_channel_args such to a hash table or AVL or some other data
+// structure that does not require linear search to find keys.
+
+/// Results reported from a grpc_resolver.
 typedef struct grpc_resolver_result grpc_resolver_result;
 
-grpc_resolver_result *grpc_resolver_result_create();
-void grpc_resolver_result_ref(grpc_resolver_result *client_config);
-void grpc_resolver_result_unref(grpc_exec_ctx *exec_ctx,
-                                grpc_resolver_result *client_config);
+/// Takes ownership of \a addresses and \a lb_policy_args.
+grpc_resolver_result* grpc_resolver_result_create(
+    grpc_lb_addresses* addresses, const char* lb_policy_name,
+    grpc_channel_args* lb_policy_args);
+void grpc_resolver_result_ref(grpc_resolver_result* result);
+void grpc_resolver_result_unref(grpc_exec_ctx* exec_ctx,
+                                grpc_resolver_result* result);
+
+/// Caller does NOT take ownership of result.
+grpc_lb_addresses* grpc_resolver_result_get_addresses(
+    grpc_resolver_result* result);
+
+/// Caller does NOT take ownership of result.
+const char* grpc_resolver_result_get_lb_policy_name(
+    grpc_resolver_result* result);
 
-void grpc_resolver_result_set_lb_policy(grpc_resolver_result *client_config,
-                                        grpc_lb_policy *lb_policy);
-grpc_lb_policy *grpc_resolver_result_get_lb_policy(
-    grpc_resolver_result *client_config);
+/// Caller does NOT take ownership of result.
+grpc_channel_args* grpc_resolver_result_get_lb_policy_args(
+    grpc_resolver_result* result);
 
 #endif /* GRPC_CORE_EXT_CLIENT_CONFIG_RESOLVER_RESULT_H */

src/core/ext/client_config/subchannel.c

@@ -33,6 +33,7 @@
 
 #include "src/core/ext/client_config/subchannel.h"
 
+#include <limits.h>
 #include <string.h>
 
 #include <grpc/support/alloc.h>
@@ -219,8 +220,8 @@ static gpr_atm ref_mutate(grpc_subchannel *c, gpr_atm delta,
                             : gpr_atm_no_barrier_fetch_add(&c->ref_pair, delta);
 #ifdef GRPC_STREAM_REFCOUNT_DEBUG
   gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
-          "SUBCHANNEL: %p % 12s 0x%08x -> 0x%08x [%s]", c, purpose, old_val,
-          old_val + delta, reason);
+          "SUBCHANNEL: %p %s 0x%08" PRIxPTR " -> 0x%08" PRIxPTR " [%s]", c,
+          purpose, old_val, old_val + delta, reason);
 #endif
   return old_val;
 }
@@ -347,21 +348,16 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
       }
       if (0 ==
           strcmp(c->args->args[i].key, GRPC_ARG_MAX_RECONNECT_BACKOFF_MS)) {
-        if (c->args->args[i].type == GRPC_ARG_INTEGER) {
-          if (c->args->args[i].value.integer >= 0) {
-            gpr_backoff_init(
-                &c->backoff_state, GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER,
-                GRPC_SUBCHANNEL_RECONNECT_JITTER,
-                GPR_MIN(c->args->args[i].value.integer,
-                        GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS * 1000),
-                c->args->args[i].value.integer);
-          } else {
-            gpr_log(GPR_ERROR, GRPC_ARG_MAX_RECONNECT_BACKOFF_MS
-                    " : must be non-negative");
-          }
-        } else {
-          gpr_log(GPR_ERROR,
-                  GRPC_ARG_MAX_RECONNECT_BACKOFF_MS " : must be an integer");
+        const grpc_integer_options options = {-1, 0, INT_MAX};
+        const int value =
+            grpc_channel_arg_get_integer(&c->args->args[i], options);
+        if (value >= 0) {
+          gpr_backoff_init(
+              &c->backoff_state, GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER,
+              GRPC_SUBCHANNEL_RECONNECT_JITTER,
+              GPR_MIN(value,
+                      GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS * 1000),
+              value);
         }
       }
     }
@@ -504,14 +500,13 @@ static void connected_subchannel_state_op(grpc_exec_ctx *exec_ctx,
                                           grpc_pollset_set *interested_parties,
                                           grpc_connectivity_state *state,
                                           grpc_closure *closure) {
-  grpc_transport_op op;
+  grpc_transport_op *op = grpc_make_transport_op(NULL);
   grpc_channel_element *elem;
-  memset(&op, 0, sizeof(op));
-  op.connectivity_state = state;
-  op.on_connectivity_state_change = closure;
-  op.bind_pollset_set = interested_parties;
+  op->connectivity_state = state;
+  op->on_connectivity_state_change = closure;
+  op->bind_pollset_set = interested_parties;
   elem = grpc_channel_stack_element(CHANNEL_STACK_FROM_CONNECTION(con), 0);
-  elem->filter->start_transport_op(exec_ctx, elem, &op);
+  elem->filter->start_transport_op(exec_ctx, elem, op);
 }
 
 void grpc_connected_subchannel_notify_on_state_change(
@@ -525,12 +520,11 @@ void grpc_connected_subchannel_notify_on_state_change(
 void grpc_connected_subchannel_ping(grpc_exec_ctx *exec_ctx,
                                     grpc_connected_subchannel *con,
                                     grpc_closure *closure) {
-  grpc_transport_op op;
+  grpc_transport_op *op = grpc_make_transport_op(NULL);
   grpc_channel_element *elem;
-  memset(&op, 0, sizeof(op));
-  op.send_ping = closure;
+  op->send_ping = closure;
   elem = grpc_channel_stack_element(CHANNEL_STACK_FROM_CONNECTION(con), 0);
-  elem->filter->start_transport_op(exec_ctx, elem, &op);
+  elem->filter->start_transport_op(exec_ctx, elem, op);
 }
 
 static void publish_transport_locked(grpc_exec_ctx *exec_ctx,

src/core/ext/lb_policy/grpclb/grpclb.c

@@ -76,9 +76,9 @@
  *    operations in progress over the old RR instance. This is done by
  *    decreasing the reference count on the old policy. The moment no more
  *    references are held on the old RR policy, it'll be destroyed and \a
- *    rr_connectivity_changed notified with a \a GRPC_CHANNEL_SHUTDOWN state.
- *    At this point we can transition to a new RR instance safely, which is done
- *    once again via \a rr_handover().
+ *    glb_rr_connectivity_changed notified with a \a GRPC_CHANNEL_SHUTDOWN
+ *    state. At this point we can transition to a new RR instance safely, which
+ *    is done once again via \a rr_handover().
  *
  *
  * Once a RR policy instance is in place (and getting updated as described),
@@ -96,6 +96,8 @@
  * - Implement LB service forwarding (point 2c. in the doc's diagram).
  */
 
+#include <errno.h>
+
 #include <string.h>
 
 #include <grpc/byte_buffer_reader.h>
@@ -105,22 +107,50 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/client_config/client_channel_factory.h"
+#include "src/core/ext/client_config/lb_policy_factory.h"
 #include "src/core/ext/client_config/lb_policy_registry.h"
 #include "src/core/ext/client_config/parse_address.h"
 #include "src/core/ext/lb_policy/grpclb/grpclb.h"
 #include "src/core/ext/lb_policy/grpclb/load_balancer_api.h"
+#include "src/core/lib/iomgr/sockaddr.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/call.h"
 #include "src/core/lib/surface/channel.h"
+#include "src/core/lib/transport/static_metadata.h"
 
 int grpc_lb_glb_trace = 0;
 
+/* add lb_token of selected subchannel (address) to the call's initial
+ * metadata */
+static void initial_metadata_add_lb_token(
+    grpc_metadata_batch *initial_metadata,
+    grpc_linked_mdelem *lb_token_mdelem_storage, grpc_mdelem *lb_token) {
+  GPR_ASSERT(lb_token_mdelem_storage != NULL);
+  GPR_ASSERT(lb_token != NULL);
+  grpc_metadata_batch_add_tail(initial_metadata, lb_token_mdelem_storage,
+                               lb_token);
+}
+
 typedef struct wrapped_rr_closure_arg {
   /* the original closure. Usually a on_complete/notify cb for pick() and ping()
    * calls against the internal RR instance, respectively. */
   grpc_closure *wrapped_closure;
 
+  /* the pick's initial metadata, kept in order to append the LB token for the
+   * pick */
+  grpc_metadata_batch *initial_metadata;
+
+  /* the picked target, used to determine which LB token to add to the pick's
+   * initial metadata */
+  grpc_connected_subchannel **target;
+
+  /* the LB token associated with the pick */
+  grpc_mdelem *lb_token;
+
+  /* storage for the lb token initial metadata mdelem */
+  grpc_linked_mdelem *lb_token_mdelem_storage;
+
   /* The RR instance related to the closure */
   grpc_lb_policy *rr_policy;
 
@@ -141,9 +171,20 @@ static void wrapped_rr_closure(grpc_exec_ctx *exec_ctx, void *arg,
               (intptr_t)wc_arg->rr_policy);
     }
     GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "wrapped_rr_closure");
+
+    /* if target is NULL, no pick has been made by the RR policy (eg, all
+     * addresses failed to connect). There won't be any user_data/token
+     * available */
+    if (wc_arg->target != NULL) {
+      initial_metadata_add_lb_token(wc_arg->initial_metadata,
+                                    wc_arg->lb_token_mdelem_storage,
+                                    GRPC_MDELEM_REF(wc_arg->lb_token));
+    }
   }
   GPR_ASSERT(wc_arg->wrapped_closure != NULL);
-  grpc_exec_ctx_sched(exec_ctx, wc_arg->wrapped_closure, error, NULL);
+
+  grpc_exec_ctx_sched(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_REF(error),
+                      NULL);
   gpr_free(wc_arg->owning_pending_node);
 }
 
@@ -164,6 +205,9 @@ typedef struct pending_pick {
   /* the initial metadata for the pick. See grpc_lb_policy_pick() */
   grpc_metadata_batch *initial_metadata;
 
+  /* storage for the lb token initial metadata mdelem */
+  grpc_linked_mdelem *lb_token_mdelem_storage;
+
   /* bitmask passed to pick() and used for selective cancelling. See
    * grpc_lb_policy_cancel_picks() */
   uint32_t initial_metadata_flags;
@@ -180,20 +224,24 @@ typedef struct pending_pick {
   wrapped_rr_closure_arg wrapped_on_complete_arg;
 } pending_pick;
 
-static void add_pending_pick(pending_pick **root, grpc_polling_entity *pollent,
-                             grpc_metadata_batch *initial_metadata,
-                             uint32_t initial_metadata_flags,
+static void add_pending_pick(pending_pick **root,
+                             const grpc_lb_policy_pick_args *pick_args,
                              grpc_connected_subchannel **target,
                              grpc_closure *on_complete) {
   pending_pick *pp = gpr_malloc(sizeof(*pp));
   memset(pp, 0, sizeof(pending_pick));
   memset(&pp->wrapped_on_complete_arg, 0, sizeof(wrapped_rr_closure_arg));
   pp->next = *root;
-  pp->pollent = pollent;
+  pp->pollent = pick_args->pollent;
   pp->target = target;
-  pp->initial_metadata = initial_metadata;
-  pp->initial_metadata_flags = initial_metadata_flags;
+  pp->initial_metadata = pick_args->initial_metadata;
+  pp->initial_metadata_flags = pick_args->initial_metadata_flags;
+  pp->lb_token_mdelem_storage = pick_args->lb_token_mdelem_storage;
   pp->wrapped_on_complete_arg.wrapped_closure = on_complete;
+  pp->wrapped_on_complete_arg.target = target;
+  pp->wrapped_on_complete_arg.initial_metadata = pick_args->initial_metadata;
+  pp->wrapped_on_complete_arg.lb_token_mdelem_storage =
+      pick_args->lb_token_mdelem_storage;
   grpc_closure_init(&pp->wrapped_on_complete, wrapped_rr_closure,
                     &pp->wrapped_on_complete_arg);
   *root = pp;
@@ -252,6 +300,9 @@ typedef struct glb_lb_policy {
    * response has arrived. */
   grpc_grpclb_serverlist *serverlist;
 
+  /** addresses from \a serverlist */
+  grpc_lb_addresses *addresses;
+
   /** list of picks that are waiting on RR's policy connectivity */
   pending_pick *pending_picks;
 
@@ -279,58 +330,132 @@ struct rr_connectivity_data {
   glb_lb_policy *glb_policy;
 };
 
-static grpc_lb_policy *create_rr(grpc_exec_ctx *exec_ctx,
-                                 const grpc_grpclb_serverlist *serverlist,
-                                 glb_lb_policy *glb_policy) {
-  /* TODO(dgq): support mixed ip version */
-  GPR_ASSERT(serverlist != NULL && serverlist->num_servers > 0);
-  char **host_ports = gpr_malloc(sizeof(char *) * serverlist->num_servers);
-  for (size_t i = 0; i < serverlist->num_servers; ++i) {
-    gpr_join_host_port(&host_ports[i], serverlist->servers[i]->ip_address,
-                       serverlist->servers[i]->port);
+static bool is_server_valid(const grpc_grpclb_server *server, size_t idx,
+                            bool log) {
+  const grpc_grpclb_ip_address *ip = &server->ip_address;
+  if (server->port >> 16 != 0) {
+    if (log) {
+      gpr_log(GPR_ERROR,
+              "Invalid port '%d' at index %zu of serverlist. Ignoring.",
+              server->port, idx);
+    }
+    return false;
   }
 
-  size_t uri_path_len;
-  char *concat_ipports = gpr_strjoin_sep(
-      (const char **)host_ports, serverlist->num_servers, ",", &uri_path_len);
+  if (ip->size != 4 && ip->size != 16) {
+    if (log) {
+      gpr_log(GPR_ERROR,
+              "Expected IP to be 4 or 16 bytes, got %d at index %zu of "
+              "serverlist. Ignoring",
+              ip->size, idx);
+    }
+    return false;
+  }
+  return true;
+}
 
-  grpc_lb_policy_args args;
-  args.client_channel_factory = glb_policy->cc_factory;
-  args.addresses = gpr_malloc(sizeof(grpc_resolved_addresses));
-  args.addresses->naddrs = serverlist->num_servers;
-  args.addresses->addrs =
-      gpr_malloc(sizeof(grpc_resolved_address) * args.addresses->naddrs);
-  size_t out_addrs_idx = 0;
+/* Returns addresses extracted from \a serverlist. */
+static grpc_lb_addresses *process_serverlist(
+    const grpc_grpclb_serverlist *serverlist) {
+  size_t num_valid = 0;
+  /* first pass: count how many are valid in order to allocate the necessary
+   * memory in a single block */
   for (size_t i = 0; i < serverlist->num_servers; ++i) {
-    grpc_uri uri;
-    struct sockaddr_storage sa;
-    size_t sa_len;
-    uri.path = host_ports[i];
-    if (parse_ipv4(&uri, &sa, &sa_len)) { /* TODO(dgq): add support for ipv6 */
-      memcpy(args.addresses->addrs[out_addrs_idx].addr, &sa, sa_len);
-      args.addresses->addrs[out_addrs_idx].len = sa_len;
-      ++out_addrs_idx;
+    if (is_server_valid(serverlist->servers[i], i, true)) ++num_valid;
+  }
+  if (num_valid == 0) return NULL;
+
+  grpc_lb_addresses *lb_addresses = grpc_lb_addresses_create(num_valid);
+
+  /* second pass: actually populate the addresses and LB tokens (aka user data
+   * to the outside world) to be read by the RR policy during its creation.
+   * Given that the validity tests are very cheap, they are performed again
+   * instead of marking the valid ones during the first pass, as this would
+   * incurr in an allocation due to the arbitrary number of server */
+  size_t addr_idx = 0;
+  for (size_t sl_idx = 0; sl_idx < serverlist->num_servers; ++sl_idx) {
+    GPR_ASSERT(addr_idx < num_valid);
+    const grpc_grpclb_server *server = serverlist->servers[sl_idx];
+    if (!is_server_valid(serverlist->servers[sl_idx], sl_idx, false)) continue;
+
+    /* address processing */
+    const uint16_t netorder_port = htons((uint16_t)server->port);
+    /* the addresses are given in binary format (a in(6)_addr struct) in
+     * server->ip_address.bytes. */
+    const grpc_grpclb_ip_address *ip = &server->ip_address;
+    grpc_resolved_address addr;
+    memset(&addr, 0, sizeof(addr));
+    if (ip->size == 4) {
+      addr.len = sizeof(struct sockaddr_in);
+      struct sockaddr_in *addr4 = (struct sockaddr_in *)&addr.addr;
+      addr4->sin_family = AF_INET;
+      memcpy(&addr4->sin_addr, ip->bytes, ip->size);
+      addr4->sin_port = netorder_port;
+    } else if (ip->size == 16) {
+      addr.len = sizeof(struct sockaddr_in6);
+      struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&addr.addr;
+      addr6->sin6_family = AF_INET;
+      memcpy(&addr6->sin6_addr, ip->bytes, ip->size);
+      addr6->sin6_port = netorder_port;
+    }
+
+    /* lb token processing */
+    void *user_data;
+    if (server->has_load_balance_token) {
+      const size_t lb_token_size =
+          GPR_ARRAY_SIZE(server->load_balance_token) - 1;
+      grpc_mdstr *lb_token_mdstr = grpc_mdstr_from_buffer(
+          (uint8_t *)server->load_balance_token, lb_token_size);
+      user_data = grpc_mdelem_from_metadata_strings(
+          GRPC_MDSTR_LOAD_REPORTING_INITIAL, lb_token_mdstr);
     } else {
-      gpr_log(GPR_ERROR, "Invalid LB service address '%s', ignoring.",
-              host_ports[i]);
+      gpr_log(GPR_ERROR,
+              "Missing LB token for backend address '%s'. The empty token will "
+              "be used instead",
+              grpc_sockaddr_to_uri((struct sockaddr *)&addr.addr));
+      user_data = GRPC_MDELEM_LOAD_REPORTING_INITIAL_EMPTY;
     }
+
+    grpc_lb_addresses_set_address(lb_addresses, addr_idx, &addr.addr, addr.len,
+                                  false /* is_balancer */,
+                                  NULL /* balancer_name */, user_data);
+    ++addr_idx;
   }
+  GPR_ASSERT(addr_idx == num_valid);
+
+  return lb_addresses;
+}
+
+/* A plugin for grpc_lb_addresses_destroy that unrefs the LB token metadata. */
+static void lb_token_destroy(void *token) {
+  if (token != NULL) GRPC_MDELEM_UNREF(token);
+}
+
+static grpc_lb_policy *create_rr(grpc_exec_ctx *exec_ctx,
+                                 const grpc_grpclb_serverlist *serverlist,
+                                 glb_lb_policy *glb_policy) {
+  GPR_ASSERT(serverlist != NULL && serverlist->num_servers > 0);
+
+  grpc_lb_policy_args args;
+  memset(&args, 0, sizeof(args));
+  args.client_channel_factory = glb_policy->cc_factory;
+  args.addresses = process_serverlist(serverlist);
 
   grpc_lb_policy *rr = grpc_lb_policy_create(exec_ctx, "round_robin", &args);
 
-  gpr_free(concat_ipports);
-  for (size_t i = 0; i < serverlist->num_servers; i++) {
-    gpr_free(host_ports[i]);
+  if (glb_policy->addresses != NULL) {
+    /* dispose of the previous version */
+    grpc_lb_addresses_destroy(glb_policy->addresses, lb_token_destroy);
   }
-  gpr_free(host_ports);
-  gpr_free(args.addresses->addrs);
-  gpr_free(args.addresses);
+  glb_policy->addresses = args.addresses;
+
   return rr;
 }
 
 static void rr_handover(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
                         grpc_error *error) {
-  GRPC_ERROR_REF(error);
+  GPR_ASSERT(glb_policy->serverlist != NULL &&
+             glb_policy->serverlist->num_servers > 0);
   glb_policy->rr_policy =
       create_rr(exec_ctx, glb_policy->serverlist, glb_policy);
 
@@ -345,8 +470,8 @@ static void rr_handover(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
       exec_ctx, glb_policy->rr_policy, &glb_policy->rr_connectivity->state,
       &glb_policy->rr_connectivity->on_change);
   grpc_connectivity_state_set(exec_ctx, &glb_policy->state_tracker,
-                              glb_policy->rr_connectivity->state, error,
-                              "rr_handover");
+                              glb_policy->rr_connectivity->state,
+                              GRPC_ERROR_REF(error), "rr_handover");
   grpc_lb_policy_exit_idle(exec_ctx, glb_policy->rr_policy);
 
   /* flush pending ops */
@@ -359,9 +484,12 @@ static void rr_handover(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
       gpr_log(GPR_INFO, "Pending pick about to PICK from 0x%" PRIxPTR "",
               (intptr_t)glb_policy->rr_policy);
     }
-    grpc_lb_policy_pick(exec_ctx, glb_policy->rr_policy, pp->pollent,
-                        pp->initial_metadata, pp->initial_metadata_flags,
-                        pp->target, &pp->wrapped_on_complete);
+    const grpc_lb_policy_pick_args pick_args = {
+        pp->pollent, pp->initial_metadata, pp->initial_metadata_flags,
+        pp->lb_token_mdelem_storage};
+    grpc_lb_policy_pick(exec_ctx, glb_policy->rr_policy, &pick_args, pp->target,
+                        (void **)&pp->wrapped_on_complete_arg.lb_token,
+                        &pp->wrapped_on_complete);
     pp->wrapped_on_complete_arg.owning_pending_node = pp;
   }
 
@@ -378,13 +506,13 @@ static void rr_handover(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
                             &pping->wrapped_notify);
     pping->wrapped_notify_arg.owning_pending_node = pping;
   }
-  GRPC_ERROR_UNREF(error);
 }
 
-static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
-                                    grpc_error *error) {
+static void glb_rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
+                                        grpc_error *error) {
   rr_connectivity_data *rr_conn_data = arg;
   glb_lb_policy *glb_policy = rr_conn_data->glb_policy;
+
   if (rr_conn_data->state == GRPC_CHANNEL_SHUTDOWN) {
     if (glb_policy->serverlist != NULL) {
       /* a RR policy is shutting down but there's a serverlist available ->
@@ -398,8 +526,8 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
     if (error == GRPC_ERROR_NONE) {
       /* RR not shutting down. Mimic the RR's policy state */
       grpc_connectivity_state_set(exec_ctx, &glb_policy->state_tracker,
-                                  rr_conn_data->state, error,
-                                  "rr_connectivity_changed");
+                                  rr_conn_data->state, GRPC_ERROR_REF(error),
+                                  "glb_rr_connectivity_changed");
       /* resubscribe */
       grpc_lb_policy_notify_on_state_change(exec_ctx, glb_policy->rr_policy,
                                             &rr_conn_data->state,
@@ -408,41 +536,63 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
       gpr_free(rr_conn_data);
     }
   }
-  GRPC_ERROR_UNREF(error);
 }
 
 static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
                                   grpc_lb_policy_factory *factory,
                                   grpc_lb_policy_args *args) {
+  /* Count the number of gRPC-LB addresses. There must be at least one.
+   * TODO(roth): For now, we ignore non-balancer addresses, but in the
+   * future, we may change the behavior such that we fall back to using
+   * the non-balancer addresses if we cannot reach any balancers. At that
+   * time, this should be changed to allow a list with no balancer addresses,
+   * since the resolver might fail to return a balancer address even when
+   * this is the right LB policy to use. */
+  size_t num_grpclb_addrs = 0;
+  for (size_t i = 0; i < args->addresses->num_addresses; ++i) {
+    if (args->addresses->addresses[i].is_balancer) ++num_grpclb_addrs;
+  }
+  if (num_grpclb_addrs == 0) return NULL;
+
   glb_lb_policy *glb_policy = gpr_malloc(sizeof(*glb_policy));
   memset(glb_policy, 0, sizeof(*glb_policy));
 
   /* All input addresses in args->addresses come from a resolver that claims
-   * they are LB services. It's the resolver's responsibility to make sure this
+   * they are LB services. It's the resolver's responsibility to make sure
+   * this
    * policy is only instantiated and used in that case.
    *
    * Create a client channel over them to communicate with a LB service */
   glb_policy->cc_factory = args->client_channel_factory;
   GPR_ASSERT(glb_policy->cc_factory != NULL);
-  if (args->addresses->naddrs == 0) {
-    return NULL;
-  }
 
-  /* construct a target from the args->addresses, in the form
+  /* construct a target from the addresses in args, given in the form
    * ipvX://ip1:port1,ip2:port2,...
    * TODO(dgq): support mixed ip version */
-  char **addr_strs = gpr_malloc(sizeof(char *) * args->addresses->naddrs);
-  addr_strs[0] =
-      grpc_sockaddr_to_uri((const struct sockaddr *)&args->addresses->addrs[0]);
-  for (size_t i = 1; i < args->addresses->naddrs; i++) {
-    GPR_ASSERT(grpc_sockaddr_to_string(
-                   &addr_strs[i],
-                   (const struct sockaddr *)&args->addresses->addrs[i],
-                   true) == 0);
+  char **addr_strs = gpr_malloc(sizeof(char *) * num_grpclb_addrs);
+  size_t addr_index = 0;
+  for (size_t i = 0; i < args->addresses->num_addresses; i++) {
+    if (args->addresses->addresses[i].user_data != NULL) {
+      gpr_log(GPR_ERROR,
+              "This LB policy doesn't support user data. It will be ignored");
+    }
+    if (args->addresses->addresses[i].is_balancer) {
+      if (addr_index == 0) {
+        addr_strs[addr_index++] = grpc_sockaddr_to_uri(
+            (const struct sockaddr *)&args->addresses->addresses[i]
+                .address.addr);
+      } else {
+        GPR_ASSERT(grpc_sockaddr_to_string(
+                       &addr_strs[addr_index++],
+                       (const struct sockaddr *)&args->addresses->addresses[i]
+                           .address.addr,
+                       true) == 0);
+      }
+    }
   }
   size_t uri_path_len;
-  char *target_uri_str = gpr_strjoin_sep(
-      (const char **)addr_strs, args->addresses->naddrs, ",", &uri_path_len);
+  char *target_uri_str = gpr_strjoin_sep((const char **)addr_strs,
+                                         num_grpclb_addrs, ",", &uri_path_len);
 
   /* will pick using pick_first */
   glb_policy->lb_channel = grpc_client_channel_factory_create_channel(
@@ -450,7 +600,7 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
       GRPC_CLIENT_CHANNEL_TYPE_LOAD_BALANCING, NULL);
 
   gpr_free(target_uri_str);
-  for (size_t i = 0; i < args->addresses->naddrs; i++) {
+  for (size_t i = 0; i < num_grpclb_addrs; i++) {
     gpr_free(addr_strs[i]);
   }
   gpr_free(addr_strs);
@@ -463,7 +613,7 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   rr_connectivity_data *rr_connectivity =
       gpr_malloc(sizeof(rr_connectivity_data));
   memset(rr_connectivity, 0, sizeof(rr_connectivity_data));
-  grpc_closure_init(&rr_connectivity->on_change, rr_connectivity_changed,
+  grpc_closure_init(&rr_connectivity->on_change, glb_rr_connectivity_changed,
                     rr_connectivity);
   rr_connectivity->glb_policy = glb_policy;
   glb_policy->rr_connectivity = rr_connectivity;
@@ -486,6 +636,7 @@ static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
     grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
   }
   gpr_mu_destroy(&glb_policy->mu);
+  grpc_lb_addresses_destroy(glb_policy->addresses, lb_token_destroy);
   gpr_free(glb_policy);
 }
 
@@ -546,7 +697,6 @@ static void glb_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
       *target = NULL;
       grpc_exec_ctx_sched(exec_ctx, &pp->wrapped_on_complete,
                           GRPC_ERROR_CANCELLED, NULL);
-      gpr_free(pp);
     } else {
       pp->next = glb_policy->pending_picks;
       glb_policy->pending_picks = pp;
@@ -576,7 +726,6 @@ static void glb_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
           exec_ctx, pp->pollent, glb_policy->base.interested_parties);
       grpc_exec_ctx_sched(exec_ctx, &pp->wrapped_on_complete,
                           GRPC_ERROR_CANCELLED, NULL);
-      gpr_free(pp);
     } else {
       pp->next = glb_policy->pending_picks;
       glb_policy->pending_picks = pp;
@@ -603,12 +752,21 @@ static void glb_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
 }
 
 static int glb_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                    grpc_polling_entity *pollent,
-                    grpc_metadata_batch *initial_metadata,
-                    uint32_t initial_metadata_flags,
-                    grpc_connected_subchannel **target,
+                    const grpc_lb_policy_pick_args *pick_args,
+                    grpc_connected_subchannel **target, void **user_data,
                     grpc_closure *on_complete) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
+
+  if (pick_args->lb_token_mdelem_storage == NULL) {
+    *target = NULL;
+    grpc_exec_ctx_sched(
+        exec_ctx, on_complete,
+        GRPC_ERROR_CREATE("No mdelem storage for the LB token. Load reporting "
+                          "won't work without it. Failing"),
+        NULL);
+    return 1;
+  }
+
   gpr_mu_lock(&glb_policy->mu);
   int r;
 
@@ -620,29 +778,36 @@ static int glb_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     GRPC_LB_POLICY_REF(glb_policy->rr_policy, "glb_pick");
     memset(&glb_policy->wc_arg, 0, sizeof(wrapped_rr_closure_arg));
     glb_policy->wc_arg.rr_policy = glb_policy->rr_policy;
+    glb_policy->wc_arg.target = target;
     glb_policy->wc_arg.wrapped_closure = on_complete;
+    glb_policy->wc_arg.lb_token_mdelem_storage =
+        pick_args->lb_token_mdelem_storage;
+    glb_policy->wc_arg.initial_metadata = pick_args->initial_metadata;
+    glb_policy->wc_arg.owning_pending_node = NULL;
     grpc_closure_init(&glb_policy->wrapped_on_complete, wrapped_rr_closure,
                       &glb_policy->wc_arg);
-    r = grpc_lb_policy_pick(exec_ctx, glb_policy->rr_policy, pollent,
-                            initial_metadata, initial_metadata_flags, target,
+
+    r = grpc_lb_policy_pick(exec_ctx, glb_policy->rr_policy, pick_args, target,
+                            (void **)&glb_policy->wc_arg.lb_token,
                             &glb_policy->wrapped_on_complete);
     if (r != 0) {
-      /* the call to grpc_lb_policy_pick has been sychronous. Unreffing the RR
-       * policy and notify the original callback */
-      glb_policy->wc_arg.wrapped_closure = NULL;
+      /* synchronous grpc_lb_policy_pick call. Unref the RR policy. */
       if (grpc_lb_glb_trace) {
         gpr_log(GPR_INFO, "Unreffing RR (0x%" PRIxPTR ")",
                 (intptr_t)glb_policy->wc_arg.rr_policy);
       }
       GRPC_LB_POLICY_UNREF(exec_ctx, glb_policy->wc_arg.rr_policy, "glb_pick");
-      grpc_exec_ctx_sched(exec_ctx, glb_policy->wc_arg.wrapped_closure,
-                          GRPC_ERROR_NONE, NULL);
+
+      /* add the load reporting initial metadata */
+      initial_metadata_add_lb_token(
+          pick_args->initial_metadata, pick_args->lb_token_mdelem_storage,
+          GRPC_MDELEM_REF(glb_policy->wc_arg.lb_token));
     }
   } else {
-    grpc_polling_entity_add_to_pollset_set(exec_ctx, pollent,
+    grpc_polling_entity_add_to_pollset_set(exec_ctx, pick_args->pollent,
                                            glb_policy->base.interested_parties);
-    add_pending_pick(&glb_policy->pending_picks, pollent, initial_metadata,
-                     initial_metadata_flags, target, on_complete);
+    add_pending_pick(&glb_policy->pending_picks, pick_args, target,
+                     on_complete);
 
     if (!glb_policy->started_picking) {
       start_picking(exec_ctx, glb_policy);
@@ -702,9 +867,6 @@ typedef struct lb_client_data {
   /* called once initial metadata's been sent */
   grpc_closure md_sent;
 
-  /* called once initial metadata's been received */
-  grpc_closure md_rcvd;
-
   /* called once the LoadBalanceRequest has been sent to the LB server. See
    * src/proto/grpc/.../load_balancer.proto */
   grpc_closure req_sent;
@@ -741,7 +903,6 @@ typedef struct lb_client_data {
 } lb_client_data;
 
 static void md_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error);
-static void md_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error);
 static void req_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error);
 static void res_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error);
 static void close_sent_cb(grpc_exec_ctx *exec_ctx, void *arg,
@@ -756,7 +917,6 @@ static lb_client_data *lb_client_data_create(glb_lb_policy *glb_policy) {
   gpr_mu_init(&lb_client->mu);
   grpc_closure_init(&lb_client->md_sent, md_sent_cb, lb_client);
 
-  grpc_closure_init(&lb_client->md_rcvd, md_recv_cb, lb_client);
   grpc_closure_init(&lb_client->req_sent, req_sent_cb, lb_client);
   grpc_closure_init(&lb_client->res_rcvd, res_recv_cb, lb_client);
   grpc_closure_init(&lb_client->close_sent, close_sent_cb, lb_client);
@@ -855,23 +1015,6 @@ static void md_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
   grpc_op ops[1];
   memset(ops, 0, sizeof(ops));
   grpc_op *op = ops;
-  op->op = GRPC_OP_RECV_INITIAL_METADATA;
-  op->data.recv_initial_metadata = &lb_client->initial_metadata_recv;
-  op->flags = 0;
-  op->reserved = NULL;
-  op++;
-  grpc_call_error call_error = grpc_call_start_batch_and_execute(
-      exec_ctx, lb_client->lb_call, ops, (size_t)(op - ops),
-      &lb_client->md_rcvd);
-  GPR_ASSERT(GRPC_CALL_OK == call_error);
-}
-
-static void md_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
-  lb_client_data *lb_client = arg;
-  GPR_ASSERT(lb_client->lb_call);
-  grpc_op ops[1];
-  memset(ops, 0, sizeof(ops));
-  grpc_op *op = ops;
 
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = lb_client->request_payload;
@@ -886,11 +1029,18 @@ static void md_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
 
 static void req_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
   lb_client_data *lb_client = arg;
+  GPR_ASSERT(lb_client->lb_call);
 
-  grpc_op ops[1];
+  grpc_op ops[2];
   memset(ops, 0, sizeof(ops));
   grpc_op *op = ops;
 
+  op->op = GRPC_OP_RECV_INITIAL_METADATA;
+  op->data.recv_initial_metadata = &lb_client->initial_metadata_recv;
+  op->flags = 0;
+  op->reserved = NULL;
+  op++;
+
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &lb_client->response_payload;
   op->flags = 0;
@@ -909,8 +1059,7 @@ static void res_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
   grpc_op *op = ops;
   if (lb_client->response_payload != NULL) {
     /* Received data from the LB server. Look inside
-     * lb_client->response_payload, for
-     * a serverlist. */
+     * lb_client->response_payload, for a serverlist. */
     grpc_byte_buffer_reader bbr;
     grpc_byte_buffer_reader_init(&bbr, lb_client->response_payload);
     gpr_slice response_slice = grpc_byte_buffer_reader_readall(&bbr);
@@ -947,7 +1096,7 @@ static void res_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
         } else {
           /* unref the RR policy, eventually leading to its substitution with a
            * new one constructed from the received serverlist (see
-           * rr_connectivity_changed) */
+           * glb_rr_connectivity_changed) */
           GRPC_LB_POLICY_UNREF(exec_ctx, lb_client->glb_policy->rr_policy,
                                "serverlist_received");
         }
@@ -1010,8 +1159,8 @@ static void srv_status_rcvd_cb(grpc_exec_ctx *exec_ctx, void *arg,
             lb_client->status, lb_client->status_details,
             lb_client->status_details_capacity);
   }
-  /* TODO(dgq): deal with stream termination properly (fire up another one? fail
-   * the original call?) */
+  /* TODO(dgq): deal with stream termination properly (fire up another one?
+   * fail the original call?) */
 }
 
 /* Code wiring the policy with the rest of the core */

src/core/ext/lb_policy/grpclb/load_balancer_api.c

@@ -57,6 +57,7 @@ static bool decode_serverlist(pb_istream_t *stream, const pb_field_t *field,
   if (dec_arg->first_pass) { /* count how many server do we have */
     grpc_grpclb_server server;
     if (!pb_decode(stream, grpc_lb_v1_Server_fields, &server)) {
+      gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(stream));
       return false;
     }
     dec_arg->num_servers++;
@@ -69,6 +70,7 @@ static bool decode_serverlist(pb_istream_t *stream, const pb_field_t *field,
           gpr_malloc(sizeof(grpc_grpclb_server *) * dec_arg->num_servers);
     }
     if (!pb_decode(stream, grpc_lb_v1_Server_fields, server)) {
+      gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(stream));
       return false;
     }
     dec_arg->servers[dec_arg->decoding_idx++] = server;
@@ -118,6 +120,7 @@ grpc_grpclb_initial_response *grpc_grpclb_initial_response_parse(
   grpc_grpclb_response res;
   memset(&res, 0, sizeof(grpc_grpclb_response));
   if (!pb_decode(&stream, grpc_lb_v1_LoadBalanceResponse_fields, &res)) {
+    gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(&stream));
     return NULL;
   }
   grpc_grpclb_initial_response *initial_res =
@@ -145,6 +148,7 @@ grpc_grpclb_serverlist *grpc_grpclb_response_parse_serverlist(
   arg.first_pass = true;
   status = pb_decode(&stream, grpc_lb_v1_LoadBalanceResponse_fields, &res);
   if (!status) {
+    gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(&stream));
     return NULL;
   }
 
@@ -152,6 +156,7 @@ grpc_grpclb_serverlist *grpc_grpclb_response_parse_serverlist(
   status =
       pb_decode(&stream_at_start, grpc_lb_v1_LoadBalanceResponse_fields, &res);
   if (!status) {
+    gpr_log(GPR_ERROR, "nanopb error: %s", PB_GET_ERROR(&stream));
     return NULL;
   }
 

src/core/ext/lb_policy/grpclb/load_balancer_api.h

@@ -45,6 +45,7 @@ extern "C" {
 
 #define GRPC_GRPCLB_SERVICE_NAME_MAX_LENGTH 128
 
+typedef grpc_lb_v1_Server_ip_address_t grpc_grpclb_ip_address;
 typedef grpc_lb_v1_LoadBalanceRequest grpc_grpclb_request;
 typedef grpc_lb_v1_InitialLoadBalanceResponse grpc_grpclb_initial_response;
 typedef grpc_lb_v1_Server grpc_grpclb_server;

src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c

@@ -31,10 +31,11 @@
  *
  */
 /* Automatically generated nanopb constant definitions */
-/* Generated by nanopb-0.3.5-dev */
+/* Generated by nanopb-0.3.7-dev */
 
 #include "src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h"
 
+/* @@protoc_insertion_point(includes) */
 #if PB_PROTO_HEADER_VERSION != 30
 #error Regenerate this file with the current version of nanopb generator.
 #endif
@@ -72,8 +73,8 @@ const pb_field_t grpc_lb_v1_LoadBalanceResponse_fields[3] = {
 };
 
 const pb_field_t grpc_lb_v1_InitialLoadBalanceResponse_fields[3] = {
-    PB_FIELD(  2, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_InitialLoadBalanceResponse, load_balancer_delegate, load_balancer_delegate, 0),
-    PB_FIELD(  3, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_InitialLoadBalanceResponse, client_stats_report_interval, load_balancer_delegate, &grpc_lb_v1_Duration_fields),
+    PB_FIELD(  1, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_InitialLoadBalanceResponse, load_balancer_delegate, load_balancer_delegate, 0),
+    PB_FIELD(  2, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_InitialLoadBalanceResponse, client_stats_report_interval, load_balancer_delegate, &grpc_lb_v1_Duration_fields),
     PB_LAST_FIELD
 };
 
@@ -84,7 +85,7 @@ const pb_field_t grpc_lb_v1_ServerList_fields[3] = {
 };
 
 const pb_field_t grpc_lb_v1_Server_fields[5] = {
-    PB_FIELD(  1, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_Server, ip_address, ip_address, 0),
+    PB_FIELD(  1, BYTES   , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_Server, ip_address, ip_address, 0),
     PB_FIELD(  2, INT32   , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_Server, port, ip_address, 0),
     PB_FIELD(  3, STRING  , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_Server, load_balance_token, port, 0),
     PB_FIELD(  4, BOOL    , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_Server, drop_request, load_balance_token, 0),
@@ -116,3 +117,4 @@ PB_STATIC_ASSERT((pb_membersize(grpc_lb_v1_LoadBalanceRequest, initial_request)
 #endif
 
 
+/* @@protoc_insertion_point(eof) */

src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h

@@ -31,11 +31,12 @@
  *
  */
 /* Automatically generated nanopb header */
-/* Generated by nanopb-0.3.5-dev */
+/* Generated by nanopb-0.3.7-dev */
 
-#ifndef GRPC_CORE_EXT_LB_POLICY_GRPCLB_PROTO_GRPC_LB_V1_LOAD_BALANCER_PB_H
-#define GRPC_CORE_EXT_LB_POLICY_GRPCLB_PROTO_GRPC_LB_V1_LOAD_BALANCER_PB_H
+#ifndef PB_GRPC_LB_V1_LOAD_BALANCER_PB_H_INCLUDED
+#define PB_GRPC_LB_V1_LOAD_BALANCER_PB_H_INCLUDED
 #include "third_party/nanopb/pb.h"
+/* @@protoc_insertion_point(includes) */
 #if PB_PROTO_HEADER_VERSION != 30
 #error Regenerate this file with the current version of nanopb generator.
 #endif
@@ -52,6 +53,7 @@ typedef struct _grpc_lb_v1_ClientStats {
     int64_t client_rpc_errors;
     bool has_dropped_requests;
     int64_t dropped_requests;
+/* @@protoc_insertion_point(struct:grpc_lb_v1_ClientStats) */
 } grpc_lb_v1_ClientStats;
 
 typedef struct _grpc_lb_v1_Duration {
@@ -59,22 +61,26 @@ typedef struct _grpc_lb_v1_Duration {
     int64_t seconds;
     bool has_nanos;
     int32_t nanos;
+/* @@protoc_insertion_point(struct:grpc_lb_v1_Duration) */
 } grpc_lb_v1_Duration;
 
 typedef struct _grpc_lb_v1_InitialLoadBalanceRequest {
     bool has_name;
     char name[128];
+/* @@protoc_insertion_point(struct:grpc_lb_v1_InitialLoadBalanceRequest) */
 } grpc_lb_v1_InitialLoadBalanceRequest;
 
+typedef PB_BYTES_ARRAY_T(16) grpc_lb_v1_Server_ip_address_t;
 typedef struct _grpc_lb_v1_Server {
     bool has_ip_address;
-    char ip_address[46];
+    grpc_lb_v1_Server_ip_address_t ip_address;
     bool has_port;
     int32_t port;
     bool has_load_balance_token;
-    char load_balance_token[64];
+    char load_balance_token[65];
     bool has_drop_request;
     bool drop_request;
+/* @@protoc_insertion_point(struct:grpc_lb_v1_Server) */
 } grpc_lb_v1_Server;
 
 typedef struct _grpc_lb_v1_InitialLoadBalanceResponse {
@@ -82,6 +88,7 @@ typedef struct _grpc_lb_v1_InitialLoadBalanceResponse {
     char load_balancer_delegate[64];
     bool has_client_stats_report_interval;
     grpc_lb_v1_Duration client_stats_report_interval;
+/* @@protoc_insertion_point(struct:grpc_lb_v1_InitialLoadBalanceResponse) */
 } grpc_lb_v1_InitialLoadBalanceResponse;
 
 typedef struct _grpc_lb_v1_LoadBalanceRequest {
@@ -89,12 +96,14 @@ typedef struct _grpc_lb_v1_LoadBalanceRequest {
     grpc_lb_v1_InitialLoadBalanceRequest initial_request;
     bool has_client_stats;
     grpc_lb_v1_ClientStats client_stats;
+/* @@protoc_insertion_point(struct:grpc_lb_v1_LoadBalanceRequest) */
 } grpc_lb_v1_LoadBalanceRequest;
 
 typedef struct _grpc_lb_v1_ServerList {
     pb_callback_t servers;
     bool has_expiration_interval;
     grpc_lb_v1_Duration expiration_interval;
+/* @@protoc_insertion_point(struct:grpc_lb_v1_ServerList) */
 } grpc_lb_v1_ServerList;
 
 typedef struct _grpc_lb_v1_LoadBalanceResponse {
@@ -102,6 +111,7 @@ typedef struct _grpc_lb_v1_LoadBalanceResponse {
     grpc_lb_v1_InitialLoadBalanceResponse initial_response;
     bool has_server_list;
     grpc_lb_v1_ServerList server_list;
+/* @@protoc_insertion_point(struct:grpc_lb_v1_LoadBalanceResponse) */
 } grpc_lb_v1_LoadBalanceResponse;
 
 /* Default values for struct fields */
@@ -114,7 +124,7 @@ typedef struct _grpc_lb_v1_LoadBalanceResponse {
 #define grpc_lb_v1_LoadBalanceResponse_init_default {false, grpc_lb_v1_InitialLoadBalanceResponse_init_default, false, grpc_lb_v1_ServerList_init_default}
 #define grpc_lb_v1_InitialLoadBalanceResponse_init_default {false, "", false, grpc_lb_v1_Duration_init_default}
 #define grpc_lb_v1_ServerList_init_default       {{{NULL}, NULL}, false, grpc_lb_v1_Duration_init_default}
-#define grpc_lb_v1_Server_init_default           {false, "", false, 0, false, "", false, 0}
+#define grpc_lb_v1_Server_init_default           {false, {0, {0}}, false, 0, false, "", false, 0}
 #define grpc_lb_v1_Duration_init_zero            {false, 0, false, 0}
 #define grpc_lb_v1_LoadBalanceRequest_init_zero  {false, grpc_lb_v1_InitialLoadBalanceRequest_init_zero, false, grpc_lb_v1_ClientStats_init_zero}
 #define grpc_lb_v1_InitialLoadBalanceRequest_init_zero {false, ""}
@@ -122,7 +132,7 @@ typedef struct _grpc_lb_v1_LoadBalanceResponse {
 #define grpc_lb_v1_LoadBalanceResponse_init_zero {false, grpc_lb_v1_InitialLoadBalanceResponse_init_zero, false, grpc_lb_v1_ServerList_init_zero}
 #define grpc_lb_v1_InitialLoadBalanceResponse_init_zero {false, "", false, grpc_lb_v1_Duration_init_zero}
 #define grpc_lb_v1_ServerList_init_zero          {{{NULL}, NULL}, false, grpc_lb_v1_Duration_init_zero}
-#define grpc_lb_v1_Server_init_zero              {false, "", false, 0, false, "", false, 0}
+#define grpc_lb_v1_Server_init_zero              {false, {0, {0}}, false, 0, false, "", false, 0}
 
 /* Field tags (for use in manual encoding/decoding) */
 #define grpc_lb_v1_ClientStats_total_requests_tag 1
@@ -135,8 +145,8 @@ typedef struct _grpc_lb_v1_LoadBalanceResponse {
 #define grpc_lb_v1_Server_port_tag               2
 #define grpc_lb_v1_Server_load_balance_token_tag 3
 #define grpc_lb_v1_Server_drop_request_tag       4
-#define grpc_lb_v1_InitialLoadBalanceResponse_load_balancer_delegate_tag 2
-#define grpc_lb_v1_InitialLoadBalanceResponse_client_stats_report_interval_tag 3
+#define grpc_lb_v1_InitialLoadBalanceResponse_load_balancer_delegate_tag 1
+#define grpc_lb_v1_InitialLoadBalanceResponse_client_stats_report_interval_tag 2
 #define grpc_lb_v1_LoadBalanceRequest_initial_request_tag 1
 #define grpc_lb_v1_LoadBalanceRequest_client_stats_tag 2
 #define grpc_lb_v1_ServerList_servers_tag        1
@@ -161,7 +171,8 @@ extern const pb_field_t grpc_lb_v1_Server_fields[5];
 #define grpc_lb_v1_ClientStats_size              33
 #define grpc_lb_v1_LoadBalanceResponse_size      (98 + grpc_lb_v1_ServerList_size)
 #define grpc_lb_v1_InitialLoadBalanceResponse_size 90
-#define grpc_lb_v1_Server_size                   127
+/* grpc_lb_v1_ServerList_size depends on runtime parameters */
+#define grpc_lb_v1_Server_size                   98
 
 /* Message IDs (where set with "msgid" option) */
 #ifdef PB_MSGID
@@ -174,5 +185,6 @@ extern const pb_field_t grpc_lb_v1_Server_fields[5];
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
+/* @@protoc_insertion_point(eof) */
 
 #endif

src/core/ext/lb_policy/pick_first/pick_first.c

@@ -199,10 +199,8 @@ static void pf_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
 }
 
 static int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                   grpc_polling_entity *pollent,
-                   grpc_metadata_batch *initial_metadata,
-                   uint32_t initial_metadata_flags,
-                   grpc_connected_subchannel **target,
+                   const grpc_lb_policy_pick_args *pick_args,
+                   grpc_connected_subchannel **target, void **user_data,
                    grpc_closure *on_complete) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   pending_pick *pp;
@@ -225,13 +223,13 @@ static int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
     }
-    grpc_polling_entity_add_to_pollset_set(exec_ctx, pollent,
+    grpc_polling_entity_add_to_pollset_set(exec_ctx, pick_args->pollent,
                                            p->base.interested_parties);
     pp = gpr_malloc(sizeof(*pp));
     pp->next = p->pending_picks;
-    pp->pollent = pollent;
+    pp->pollent = pick_args->pollent;
     pp->target = target;
-    pp->initial_metadata_flags = initial_metadata_flags;
+    pp->initial_metadata_flags = pick_args->initial_metadata_flags;
     pp->on_complete = on_complete;
     p->pending_picks = pp;
     gpr_mu_unlock(&p->mu);
@@ -443,20 +441,34 @@ static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(args->addresses != NULL);
   GPR_ASSERT(args->client_channel_factory != NULL);
 
-  if (args->addresses->naddrs == 0) return NULL;
+  /* Find the number of backend addresses. We ignore balancer
+   * addresses, since we don't know how to handle them. */
+  size_t num_addrs = 0;
+  for (size_t i = 0; i < args->addresses->num_addresses; i++) {
+    if (!args->addresses->addresses[i].is_balancer) ++num_addrs;
+  }
+  if (num_addrs == 0) return NULL;
 
   pick_first_lb_policy *p = gpr_malloc(sizeof(*p));
   memset(p, 0, sizeof(*p));
 
-  p->subchannels =
-      gpr_malloc(sizeof(grpc_subchannel *) * args->addresses->naddrs);
-  memset(p->subchannels, 0, sizeof(*p->subchannels) * args->addresses->naddrs);
+  p->subchannels = gpr_malloc(sizeof(grpc_subchannel *) * num_addrs);
+  memset(p->subchannels, 0, sizeof(*p->subchannels) * num_addrs);
   grpc_subchannel_args sc_args;
   size_t subchannel_idx = 0;
-  for (size_t i = 0; i < args->addresses->naddrs; i++) {
+  for (size_t i = 0; i < args->addresses->num_addresses; i++) {
+    /* Skip balancer addresses, since we only know how to handle backends. */
+    if (args->addresses->addresses[i].is_balancer) continue;
+
+    if (args->addresses->addresses[i].user_data != NULL) {
+      gpr_log(GPR_ERROR,
+              "This LB policy doesn't support user data. It will be ignored");
+    }
+
     memset(&sc_args, 0, sizeof(grpc_subchannel_args));
-    sc_args.addr = (struct sockaddr *)(args->addresses->addrs[i].addr);
-    sc_args.addr_len = (size_t)args->addresses->addrs[i].len;
+    sc_args.addr =
+        (struct sockaddr *)(&args->addresses->addresses[i].address.addr);
+    sc_args.addr_len = args->addresses->addresses[i].address.len;
 
     grpc_subchannel *subchannel = grpc_client_channel_factory_create_subchannel(
         exec_ctx, args->client_channel_factory, &sc_args);

src/core/ext/lb_policy/round_robin/round_robin.c

@@ -66,6 +66,7 @@
 #include "src/core/ext/client_config/lb_policy_registry.h"
 #include "src/core/lib/debug/trace.h"
 #include "src/core/lib/transport/connectivity_state.h"
+#include "src/core/lib/transport/static_metadata.h"
 
 typedef struct round_robin_lb_policy round_robin_lb_policy;
 
@@ -76,15 +77,32 @@ int grpc_lb_round_robin_trace = 0;
  * Once a pick is available, \a target is updated and \a on_complete called. */
 typedef struct pending_pick {
   struct pending_pick *next;
+
+  /* polling entity for the pick()'s async notification */
   grpc_polling_entity *pollent;
+
+  /* output argument where to store the pick()ed user_data. It'll be NULL if no
+   * such data is present or there's an error (the definite test for errors is
+   * \a target being NULL). */
+  void **user_data;
+
+  /* bitmask passed to pick() and used for selective cancelling. See
+   * grpc_lb_policy_cancel_picks() */
   uint32_t initial_metadata_flags;
+
+  /* output argument where to store the pick()ed connected subchannel, or NULL
+   * upon error. */
   grpc_connected_subchannel **target;
+
+  /* to be invoked once the pick() has completed (regardless of success) */
   grpc_closure *on_complete;
 } pending_pick;
 
 /** List of subchannels in a connectivity READY state */
 typedef struct ready_list {
   grpc_subchannel *subchannel;
+  /* references namesake entry in subchannel_data */
+  void *user_data;
   struct ready_list *next;
   struct ready_list *prev;
 } ready_list;
@@ -102,12 +120,17 @@ typedef struct {
   ready_list *ready_list_node;
   /** last observed connectivity */
   grpc_connectivity_state connectivity_state;
+  /** the subchannel's target user data */
+  void *user_data;
 } subchannel_data;
 
 struct round_robin_lb_policy {
   /** base policy: must be first */
   grpc_lb_policy base;
 
+  /** total number of addresses received at creation time */
+  size_t num_addresses;
+
   /** all our subchannels */
   size_t num_subchannels;
   subchannel_data **subchannels;
@@ -166,16 +189,19 @@ static void advance_last_picked_locked(round_robin_lb_policy *p) {
 
   if (grpc_lb_round_robin_trace) {
     gpr_log(GPR_DEBUG, "[READYLIST] ADVANCED LAST PICK. NOW AT NODE %p (SC %p)",
-            p->ready_list_last_pick, p->ready_list_last_pick->subchannel);
+            (void *)p->ready_list_last_pick,
+            (void *)p->ready_list_last_pick->subchannel);
   }
 }
 
 /** Prepends (relative to the root at p->ready_list) the connected subchannel \a
  * csc to the list of ready subchannels. */
 static ready_list *add_connected_sc_locked(round_robin_lb_policy *p,
-                                           grpc_subchannel *sc) {
+                                           subchannel_data *sd) {
   ready_list *new_elem = gpr_malloc(sizeof(ready_list));
-  new_elem->subchannel = sc;
+  memset(new_elem, 0, sizeof(ready_list));
+  new_elem->subchannel = sd->subchannel;
+  new_elem->user_data = sd->user_data;
   if (p->ready_list.prev == NULL) {
     /* first element */
     new_elem->next = &p->ready_list;
@@ -189,7 +215,8 @@ static ready_list *add_connected_sc_locked(round_robin_lb_policy *p,
     p->ready_list.prev = new_elem;
   }
   if (grpc_lb_round_robin_trace) {
-    gpr_log(GPR_DEBUG, "[READYLIST] ADDING NODE %p (SC %p)", new_elem, sc);
+    gpr_log(GPR_DEBUG, "[READYLIST] ADDING NODE %p (Conn. SC %p)",
+            (void *)new_elem, (void *)sd->subchannel);
   }
   return new_elem;
 }
@@ -216,8 +243,8 @@ static void remove_disconnected_sc_locked(round_robin_lb_policy *p,
   }
 
   if (grpc_lb_round_robin_trace) {
-    gpr_log(GPR_DEBUG, "[READYLIST] REMOVED NODE %p (SC %p)", node,
-            node->subchannel);
+    gpr_log(GPR_DEBUG, "[READYLIST] REMOVED NODE %p (SC %p)", (void *)node,
+            (void *)node->subchannel);
   }
 
   node->next = NULL;
@@ -229,9 +256,8 @@ static void remove_disconnected_sc_locked(round_robin_lb_policy *p,
 
 static void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
-  size_t i;
   ready_list *elem;
-  for (i = 0; i < p->num_subchannels; i++) {
+  for (size_t i = 0; i < p->num_subchannels; i++) {
     subchannel_data *sd = p->subchannels[i];
     GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel, "round_robin");
     gpr_free(sd);
@@ -251,6 +277,7 @@ static void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
     gpr_free(elem);
     elem = tmp;
   }
+
   gpr_free(p);
 }
 
@@ -337,7 +364,7 @@ static void start_picking(grpc_exec_ctx *exec_ctx, round_robin_lb_policy *p) {
   p->started_picking = 1;
 
   if (grpc_lb_round_robin_trace) {
-    gpr_log(GPR_DEBUG, "LB_POLICY: p=%p num_subchannels=%" PRIuPTR, p,
+    gpr_log(GPR_DEBUG, "LB_POLICY: p=%p num_subchannels=%" PRIuPTR, (void *)p,
             p->num_subchannels);
   }
 
@@ -361,38 +388,43 @@ static void rr_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
 }
 
 static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                   grpc_polling_entity *pollent,
-                   grpc_metadata_batch *initial_metadata,
-                   uint32_t initial_metadata_flags,
-                   grpc_connected_subchannel **target,
+                   const grpc_lb_policy_pick_args *pick_args,
+                   grpc_connected_subchannel **target, void **user_data,
                    grpc_closure *on_complete) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
   pending_pick *pp;
   ready_list *selected;
   gpr_mu_lock(&p->mu);
   if ((selected = peek_next_connected_locked(p))) {
+    /* readily available, report right away */
     gpr_mu_unlock(&p->mu);
     *target = grpc_subchannel_get_connected_subchannel(selected->subchannel);
+
+    if (user_data != NULL) {
+      *user_data = selected->user_data;
+    }
     if (grpc_lb_round_robin_trace) {
       gpr_log(GPR_DEBUG,
-              "[RR PICK] TARGET <-- CONNECTED SUBCHANNEL %p (NODE %p)", *target,
-              selected);
+              "[RR PICK] TARGET <-- CONNECTED SUBCHANNEL %p (NODE %p)",
+              (void *)*target, (void *)selected);
     }
     /* only advance the last picked pointer if the selection was used */
     advance_last_picked_locked(p);
     return 1;
   } else {
+    /* no pick currently available. Save for later in list of pending picks */
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
     }
-    grpc_polling_entity_add_to_pollset_set(exec_ctx, pollent,
+    grpc_polling_entity_add_to_pollset_set(exec_ctx, pick_args->pollent,
                                            p->base.interested_parties);
     pp = gpr_malloc(sizeof(*pp));
     pp->next = p->pending_picks;
-    pp->pollent = pollent;
+    pp->pollent = pick_args->pollent;
     pp->target = target;
     pp->on_complete = on_complete;
-    pp->initial_metadata_flags = initial_metadata_flags;
+    pp->initial_metadata_flags = pick_args->initial_metadata_flags;
+    pp->user_data = user_data;
     p->pending_picks = pp;
     gpr_mu_unlock(&p->mu);
     return 0;
@@ -421,7 +453,7 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
                                     "connecting_ready");
         /* add the newly connected subchannel to the list of connected ones.
          * Note that it goes to the "end of the line". */
-        sd->ready_list_node = add_connected_sc_locked(p, sd->subchannel);
+        sd->ready_list_node = add_connected_sc_locked(p, sd);
         /* at this point we know there's at least one suitable subchannel. Go
          * ahead and pick one and notify the pending suitors in
          * p->pending_picks. This preemtively replicates rr_pick()'s actions. */
@@ -433,12 +465,16 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
         }
         while ((pp = p->pending_picks)) {
           p->pending_picks = pp->next;
+
           *pp->target =
               grpc_subchannel_get_connected_subchannel(selected->subchannel);
+          if (pp->user_data != NULL) {
+            *pp->user_data = selected->user_data;
+          }
           if (grpc_lb_round_robin_trace) {
             gpr_log(GPR_DEBUG,
                     "[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)",
-                    selected->subchannel, selected);
+                    (void *)selected->subchannel, (void *)selected);
           }
           grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
                                                    p->base.interested_parties);
@@ -571,19 +607,31 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(args->addresses != NULL);
   GPR_ASSERT(args->client_channel_factory != NULL);
 
+  /* Find the number of backend addresses. We ignore balancer
+   * addresses, since we don't know how to handle them. */
+  size_t num_addrs = 0;
+  for (size_t i = 0; i < args->addresses->num_addresses; i++) {
+    if (!args->addresses->addresses[i].is_balancer) ++num_addrs;
+  }
+  if (num_addrs == 0) return NULL;
+
   round_robin_lb_policy *p = gpr_malloc(sizeof(*p));
   memset(p, 0, sizeof(*p));
 
-  p->subchannels =
-      gpr_malloc(sizeof(*p->subchannels) * args->addresses->naddrs);
-  memset(p->subchannels, 0, sizeof(*p->subchannels) * args->addresses->naddrs);
+  p->num_addresses = num_addrs;
+  p->subchannels = gpr_malloc(sizeof(*p->subchannels) * num_addrs);
+  memset(p->subchannels, 0, sizeof(*p->subchannels) * num_addrs);
 
   grpc_subchannel_args sc_args;
   size_t subchannel_idx = 0;
-  for (size_t i = 0; i < args->addresses->naddrs; i++) {
+  for (size_t i = 0; i < args->addresses->num_addresses; i++) {
+    /* Skip balancer addresses, since we only know how to handle backends. */
+    if (args->addresses->addresses[i].is_balancer) continue;
+
     memset(&sc_args, 0, sizeof(grpc_subchannel_args));
-    sc_args.addr = (struct sockaddr *)(args->addresses->addrs[i].addr);
-    sc_args.addr_len = (size_t)args->addresses->addrs[i].len;
+    sc_args.addr =
+        (struct sockaddr *)(&args->addresses->addresses[i].address.addr);
+    sc_args.addr_len = args->addresses->addresses[i].address.len;
 
     grpc_subchannel *subchannel = grpc_client_channel_factory_create_subchannel(
         exec_ctx, args->client_channel_factory, &sc_args);
@@ -595,12 +643,14 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
       sd->policy = p;
       sd->index = subchannel_idx;
       sd->subchannel = subchannel;
+      sd->user_data = args->addresses->addresses[i].user_data;
       ++subchannel_idx;
       grpc_closure_init(&sd->connectivity_changed_closure,
                         rr_connectivity_changed, sd);
     }
   }
   if (subchannel_idx == 0) {
+    /* couldn't create any subchannel. Bail out */
     gpr_free(p->subchannels);
     gpr_free(p);
     return NULL;

src/core/ext/resolver/dns/native/dns_resolver.c

@@ -37,7 +37,6 @@
 #include <grpc/support/host_port.h>
 #include <grpc/support/string_util.h>
 
-#include "src/core/ext/client_config/lb_policy_registry.h"
 #include "src/core/ext/client_config/resolver_registry.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/timer.h"
@@ -58,8 +57,6 @@ typedef struct {
   char *name;
   /** default port to use */
   char *default_port;
-  /** subchannel factory */
-  grpc_client_channel_factory *client_channel_factory;
   /** load balancing policy name */
   char *lb_policy_name;
 
@@ -166,24 +163,20 @@ static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
                             grpc_error *error) {
   dns_resolver *r = arg;
   grpc_resolver_result *result = NULL;
-  grpc_lb_policy *lb_policy;
   gpr_mu_lock(&r->mu);
   GPR_ASSERT(r->resolving);
   r->resolving = 0;
-  grpc_resolved_addresses *addresses = r->addresses;
-  if (addresses != NULL) {
-    grpc_lb_policy_args lb_policy_args;
-    result = grpc_resolver_result_create();
-    memset(&lb_policy_args, 0, sizeof(lb_policy_args));
-    lb_policy_args.addresses = addresses;
-    lb_policy_args.client_channel_factory = r->client_channel_factory;
-    lb_policy =
-        grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
-    if (lb_policy != NULL) {
-      grpc_resolver_result_set_lb_policy(result, lb_policy);
-      GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "construction");
+  if (r->addresses != NULL) {
+    grpc_lb_addresses *addresses =
+        grpc_lb_addresses_create(r->addresses->naddrs);
+    for (size_t i = 0; i < r->addresses->naddrs; ++i) {
+      grpc_lb_addresses_set_address(
+          addresses, i, &r->addresses->addrs[i].addr,
+          r->addresses->addrs[i].len, false /* is_balancer */,
+          NULL /* balancer_name */, NULL /* user_data */);
     }
-    grpc_resolved_addresses_destroy(addresses);
+    grpc_resolved_addresses_destroy(r->addresses);
+    result = grpc_resolver_result_create(addresses, r->lb_policy_name, NULL);
   } else {
     gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
     gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
@@ -244,7 +237,6 @@ static void dns_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
   if (r->resolved_result) {
     grpc_resolver_result_unref(exec_ctx, r->resolved_result);
   }
-  grpc_client_channel_factory_unref(exec_ctx, r->client_channel_factory);
   gpr_free(r->name);
   gpr_free(r->default_port);
   gpr_free(r->lb_policy_name);
@@ -271,10 +263,8 @@ static grpc_resolver *dns_create(grpc_resolver_args *args,
   grpc_resolver_init(&r->base, &dns_resolver_vtable);
   r->name = gpr_strdup(path);
   r->default_port = gpr_strdup(default_port);
-  r->client_channel_factory = args->client_channel_factory;
   gpr_backoff_init(&r->backoff_state, BACKOFF_MULTIPLIER, BACKOFF_JITTER,
                    BACKOFF_MIN_SECONDS * 1000, BACKOFF_MAX_SECONDS * 1000);
-  grpc_client_channel_factory_ref(r->client_channel_factory);
   r->lb_policy_name = gpr_strdup(lb_policy_name);
   return &r->base;
 }

src/core/ext/resolver/sockaddr/sockaddr_resolver.c

@@ -40,7 +40,6 @@
 #include <grpc/support/port_platform.h>
 #include <grpc/support/string_util.h>
 
-#include "src/core/ext/client_config/lb_policy_registry.h"
 #include "src/core/ext/client_config/parse_address.h"
 #include "src/core/ext/client_config/resolver_registry.h"
 #include "src/core/lib/iomgr/resolve_address.h"
@@ -52,18 +51,16 @@ typedef struct {
   grpc_resolver base;
   /** refcount */
   gpr_refcount refs;
-  /** subchannel factory */
-  grpc_client_channel_factory *client_channel_factory;
   /** load balancing policy name */
   char *lb_policy_name;
 
   /** the addresses that we've 'resolved' */
-  grpc_resolved_addresses *addresses;
+  grpc_lb_addresses *addresses;
 
   /** mutex guarding the rest of the state */
   gpr_mu mu;
   /** have we published? */
-  int published;
+  bool published;
   /** pending next completion, or NULL */
   grpc_closure *next_completion;
   /** target result address for next completion */
@@ -102,7 +99,7 @@ static void sockaddr_channel_saw_error(grpc_exec_ctx *exec_ctx,
                                        grpc_resolver *resolver) {
   sockaddr_resolver *r = (sockaddr_resolver *)resolver;
   gpr_mu_lock(&r->mu);
-  r->published = 0;
+  r->published = false;
   sockaddr_maybe_finish_next_locked(exec_ctx, r);
   gpr_mu_unlock(&r->mu);
 }
@@ -122,17 +119,10 @@ static void sockaddr_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
 static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
                                               sockaddr_resolver *r) {
   if (r->next_completion != NULL && !r->published) {
-    grpc_resolver_result *result = grpc_resolver_result_create();
-    grpc_lb_policy_args lb_policy_args;
-    memset(&lb_policy_args, 0, sizeof(lb_policy_args));
-    lb_policy_args.addresses = r->addresses;
-    lb_policy_args.client_channel_factory = r->client_channel_factory;
-    grpc_lb_policy *lb_policy =
-        grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
-    grpc_resolver_result_set_lb_policy(result, lb_policy);
-    GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "sockaddr");
-    r->published = 1;
-    *r->target_result = result;
+    r->published = true;
+    *r->target_result = grpc_resolver_result_create(
+        grpc_lb_addresses_copy(r->addresses, NULL /* user_data_copy */),
+        r->lb_policy_name, NULL);
     grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
     r->next_completion = NULL;
   }
@@ -141,8 +131,7 @@ static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
 static void sockaddr_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
   sockaddr_resolver *r = (sockaddr_resolver *)gr;
   gpr_mu_destroy(&r->mu);
-  grpc_client_channel_factory_unref(exec_ctx, r->client_channel_factory);
-  grpc_resolved_addresses_destroy(r->addresses);
+  grpc_lb_addresses_destroy(r->addresses, NULL /* user_data_destroy */);
   gpr_free(r->lb_policy_name);
   gpr_free(r);
 }
@@ -175,7 +164,7 @@ static void do_nothing(void *ignored) {}
 static grpc_resolver *sockaddr_create(
     grpc_resolver_args *args, const char *default_lb_policy_name,
     int parse(grpc_uri *uri, struct sockaddr_storage *dst, size_t *len)) {
-  int errors_found = 0; /* GPR_FALSE */
+  bool errors_found = false;
   sockaddr_resolver *r;
   gpr_slice path_slice;
   gpr_slice_buffer path_parts;
@@ -216,21 +205,18 @@ static grpc_resolver *sockaddr_create(
   gpr_slice_buffer_init(&path_parts);
 
   gpr_slice_split(path_slice, ",", &path_parts);
-  r->addresses = gpr_malloc(sizeof(grpc_resolved_addresses));
-  r->addresses->naddrs = path_parts.count;
-  r->addresses->addrs =
-      gpr_malloc(sizeof(grpc_resolved_address) * r->addresses->naddrs);
-
-  for (size_t i = 0; i < r->addresses->naddrs; i++) {
+  r->addresses = grpc_lb_addresses_create(path_parts.count);
+  for (size_t i = 0; i < r->addresses->num_addresses; i++) {
     grpc_uri ith_uri = *args->uri;
     char *part_str = gpr_dump_slice(path_parts.slices[i], GPR_DUMP_ASCII);
     ith_uri.path = part_str;
-    if (!parse(&ith_uri,
-               (struct sockaddr_storage *)(&r->addresses->addrs[i].addr),
-               &r->addresses->addrs[i].len)) {
-      errors_found = 1; /* GPR_TRUE */
+    if (!parse(&ith_uri, (struct sockaddr_storage *)(&r->addresses->addresses[i]
+                                                          .address.addr),
+               &r->addresses->addresses[i].address.len)) {
+      errors_found = true;
     }
     gpr_free(part_str);
+    r->addresses->addresses[i].is_balancer = lb_enabled;
     if (errors_found) break;
   }
 
@@ -238,7 +224,7 @@ static grpc_resolver *sockaddr_create(
   gpr_slice_unref(path_slice);
   if (errors_found) {
     gpr_free(r->lb_policy_name);
-    grpc_resolved_addresses_destroy(r->addresses);
+    grpc_lb_addresses_destroy(r->addresses, NULL /* user_data_destroy */);
     gpr_free(r);
     return NULL;
   }
@@ -246,8 +232,6 @@ static grpc_resolver *sockaddr_create(
   gpr_ref_init(&r->refs, 1);
   gpr_mu_init(&r->mu);
   grpc_resolver_init(&r->base, &sockaddr_resolver_vtable);
-  r->client_channel_factory = args->client_channel_factory;
-  grpc_client_channel_factory_ref(r->client_channel_factory);
 
   return &r->base;
 }

src/core/ext/transport/chttp2/client/insecure/channel_create.c

@@ -160,7 +160,6 @@ typedef struct {
   grpc_client_channel_factory base;
   gpr_refcount refs;
   grpc_channel_args *merge_args;
-  grpc_channel *master;
 } client_channel_factory;
 
 static void client_channel_factory_ref(
@@ -173,10 +172,6 @@ static void client_channel_factory_unref(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory) {
   client_channel_factory *f = (client_channel_factory *)cc_factory;
   if (gpr_unref(&f->refs)) {
-    if (f->master != NULL) {
-      GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, f->master,
-                                  "client_channel_factory");
-    }
     grpc_channel_args_destroy(f->merge_args);
     gpr_free(f);
   }
@@ -210,15 +205,15 @@ static grpc_channel *client_channel_factory_create_channel(
   grpc_channel *channel = grpc_channel_create(exec_ctx, target, final_args,
                                               GRPC_CLIENT_CHANNEL, NULL);
   grpc_channel_args_destroy(final_args);
-  grpc_resolver *resolver = grpc_resolver_create(target, &f->base);
+  grpc_resolver *resolver = grpc_resolver_create(target);
   if (!resolver) {
     GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, channel,
                                 "client_channel_factory_create_channel");
     return NULL;
   }
 
-  grpc_client_channel_set_resolver(
-      exec_ctx, grpc_channel_get_channel_stack(channel), resolver);
+  grpc_client_channel_finish_initialization(
+      exec_ctx, grpc_channel_get_channel_stack(channel), resolver, &f->base);
   GRPC_RESOLVER_UNREF(exec_ctx, resolver, "create_channel");
 
   return channel;
@@ -250,12 +245,8 @@ grpc_channel *grpc_insecure_channel_create(const char *target,
 
   grpc_channel *channel = client_channel_factory_create_channel(
       &exec_ctx, &f->base, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, NULL);
-  if (channel != NULL) {
-    f->master = channel;
-    GRPC_CHANNEL_INTERNAL_REF(f->master, "grpc_insecure_channel_create");
-  }
-  grpc_client_channel_factory_unref(&exec_ctx, &f->base);
 
+  grpc_client_channel_factory_unref(&exec_ctx, &f->base);
   grpc_exec_ctx_finish(&exec_ctx);
 
   return channel != NULL ? channel : grpc_lame_client_channel_create(

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

@@ -220,7 +220,6 @@ typedef struct {
   gpr_refcount refs;
   grpc_channel_args *merge_args;
   grpc_channel_security_connector *security_connector;
-  grpc_channel *master;
 } client_channel_factory;
 
 static void client_channel_factory_ref(
@@ -235,10 +234,6 @@ static void client_channel_factory_unref(
   if (gpr_unref(&f->refs)) {
     GRPC_SECURITY_CONNECTOR_UNREF(&f->security_connector->base,
                                   "client_channel_factory");
-    if (f->master != NULL) {
-      GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, f->master,
-                                  "client_channel_factory");
-    }
     grpc_channel_args_destroy(f->merge_args);
     gpr_free(f);
   }
@@ -276,10 +271,10 @@ static grpc_channel *client_channel_factory_create_channel(
                                               GRPC_CLIENT_CHANNEL, NULL);
   grpc_channel_args_destroy(final_args);
 
-  grpc_resolver *resolver = grpc_resolver_create(target, &f->base);
+  grpc_resolver *resolver = grpc_resolver_create(target);
   if (resolver != NULL) {
-    grpc_client_channel_set_resolver(
-        exec_ctx, grpc_channel_get_channel_stack(channel), resolver);
+    grpc_client_channel_finish_initialization(
+        exec_ctx, grpc_channel_get_channel_stack(channel), resolver, &f->base);
     GRPC_RESOLVER_UNREF(exec_ctx, resolver, "create");
   } else {
     GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, channel,
@@ -356,10 +351,6 @@ grpc_channel *grpc_secure_channel_create(grpc_channel_credentials *creds,
 
   grpc_channel *channel = client_channel_factory_create_channel(
       &exec_ctx, &f->base, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, NULL);
-  if (channel != NULL) {
-    f->master = channel;
-    GRPC_CHANNEL_INTERNAL_REF(f->master, "grpc_secure_channel_create");
-  }
 
   grpc_client_channel_factory_unref(&exec_ctx, &f->base);
   grpc_exec_ctx_finish(&exec_ctx);

src/core/ext/transport/chttp2/transport/chttp2_plugin.c

@@ -36,14 +36,11 @@
 #include "src/core/lib/debug/trace.h"
 #include "src/core/lib/transport/metadata.h"
 
-extern int grpc_http_write_state_trace;
-
 void grpc_chttp2_plugin_init(void) {
   grpc_chttp2_base64_encode_and_huffman_compress =
       grpc_chttp2_base64_encode_and_huffman_compress_impl;
   grpc_register_tracer("http", &grpc_http_trace);
   grpc_register_tracer("flowctl", &grpc_flowctl_trace);
-  grpc_register_tracer("http_write_state", &grpc_http_write_state_trace);
 }
 
 void grpc_chttp2_plugin_shutdown(void) {}

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

@@ -40,8 +40,8 @@
 #include "src/core/lib/iomgr/error.h"
 
 /* defined in internal.h */
-typedef struct grpc_chttp2_stream_parsing grpc_chttp2_stream_parsing;
-typedef struct grpc_chttp2_transport_parsing grpc_chttp2_transport_parsing;
+typedef struct grpc_chttp2_stream grpc_chttp2_stream;
+typedef struct grpc_chttp2_transport grpc_chttp2_transport;
 
 #define GRPC_CHTTP2_FRAME_DATA 0
 #define GRPC_CHTTP2_FRAME_HEADER 1

src/core/ext/transport/chttp2/transport/frame_data.c

@@ -51,16 +51,11 @@ grpc_error *grpc_chttp2_data_parser_init(grpc_chttp2_data_parser *parser) {
 
 void grpc_chttp2_data_parser_destroy(grpc_exec_ctx *exec_ctx,
                                      grpc_chttp2_data_parser *parser) {
-  grpc_byte_stream *bs;
-  if (parser->parsing_frame) {
+  if (parser->parsing_frame != NULL) {
     grpc_chttp2_incoming_byte_stream_finished(
-        exec_ctx, parser->parsing_frame, GRPC_ERROR_CREATE("Parser destroyed"),
-        1);
-  }
-  while (
-      (bs = grpc_chttp2_incoming_frame_queue_pop(&parser->incoming_frames))) {
-    grpc_byte_stream_destroy(exec_ctx, bs);
+        exec_ctx, parser->parsing_frame, GRPC_ERROR_CREATE("Parser destroyed"));
   }
+  GRPC_ERROR_UNREF(parser->error);
 }
 
 grpc_error *grpc_chttp2_data_parser_begin_frame(grpc_chttp2_data_parser *parser,
@@ -145,22 +140,17 @@ void grpc_chttp2_encode_data(uint32_t id, gpr_slice_buffer *inbuf,
   stats->data_bytes += write_bytes;
 }
 
-grpc_error *grpc_chttp2_data_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last) {
+static grpc_error *parse_inner(grpc_exec_ctx *exec_ctx,
+                               grpc_chttp2_data_parser *p,
+                               grpc_chttp2_transport *t, grpc_chttp2_stream *s,
+                               gpr_slice slice) {
   uint8_t *const beg = GPR_SLICE_START_PTR(slice);
   uint8_t *const end = GPR_SLICE_END_PTR(slice);
   uint8_t *cur = beg;
-  grpc_chttp2_data_parser *p = parser;
   uint32_t message_flags;
   grpc_chttp2_incoming_byte_stream *incoming_byte_stream;
   char *msg;
 
-  if (is_last && p->is_last_frame) {
-    stream_parsing->received_close = 1;
-  }
-
   if (cur == end) {
     return GRPC_ERROR_NONE;
   }
@@ -171,7 +161,7 @@ grpc_error *grpc_chttp2_data_parser_parse(
       return GRPC_ERROR_REF(p->error);
     fh_0:
     case GRPC_CHTTP2_DATA_FH_0:
-      stream_parsing->stats.incoming.framing_bytes++;
+      s->stats.incoming.framing_bytes++;
       p->frame_type = *cur;
       switch (p->frame_type) {
         case 0:
@@ -184,7 +174,7 @@ grpc_error *grpc_chttp2_data_parser_parse(
           gpr_asprintf(&msg, "Bad GRPC frame type 0x%02x", p->frame_type);
           p->error = GRPC_ERROR_CREATE(msg);
           p->error = grpc_error_set_int(p->error, GRPC_ERROR_INT_STREAM_ID,
-                                        (intptr_t)stream_parsing->id);
+                                        (intptr_t)s->id);
           gpr_free(msg);
           msg = gpr_dump_slice(slice, GPR_DUMP_HEX | GPR_DUMP_ASCII);
           p->error =
@@ -201,7 +191,7 @@ grpc_error *grpc_chttp2_data_parser_parse(
       }
     /* fallthrough */
     case GRPC_CHTTP2_DATA_FH_1:
-      stream_parsing->stats.incoming.framing_bytes++;
+      s->stats.incoming.framing_bytes++;
       p->frame_size = ((uint32_t)*cur) << 24;
       if (++cur == end) {
         p->state = GRPC_CHTTP2_DATA_FH_2;
@@ -209,7 +199,7 @@ grpc_error *grpc_chttp2_data_parser_parse(
       }
     /* fallthrough */
     case GRPC_CHTTP2_DATA_FH_2:
-      stream_parsing->stats.incoming.framing_bytes++;
+      s->stats.incoming.framing_bytes++;
       p->frame_size |= ((uint32_t)*cur) << 16;
       if (++cur == end) {
         p->state = GRPC_CHTTP2_DATA_FH_3;
@@ -217,7 +207,7 @@ grpc_error *grpc_chttp2_data_parser_parse(
       }
     /* fallthrough */
     case GRPC_CHTTP2_DATA_FH_3:
-      stream_parsing->stats.incoming.framing_bytes++;
+      s->stats.incoming.framing_bytes++;
       p->frame_size |= ((uint32_t)*cur) << 8;
       if (++cur == end) {
         p->state = GRPC_CHTTP2_DATA_FH_4;
@@ -225,7 +215,7 @@ grpc_error *grpc_chttp2_data_parser_parse(
       }
     /* fallthrough */
     case GRPC_CHTTP2_DATA_FH_4:
-      stream_parsing->stats.incoming.framing_bytes++;
+      s->stats.incoming.framing_bytes++;
       p->frame_size |= ((uint32_t)*cur);
       p->state = GRPC_CHTTP2_DATA_FRAME;
       ++cur;
@@ -234,35 +224,32 @@ grpc_error *grpc_chttp2_data_parser_parse(
         message_flags |= GRPC_WRITE_INTERNAL_COMPRESS;
       }
       p->parsing_frame = incoming_byte_stream =
-          grpc_chttp2_incoming_byte_stream_create(
-              exec_ctx, transport_parsing, stream_parsing, p->frame_size,
-              message_flags, &p->incoming_frames);
+          grpc_chttp2_incoming_byte_stream_create(exec_ctx, t, s, p->frame_size,
+                                                  message_flags);
     /* fallthrough */
     case GRPC_CHTTP2_DATA_FRAME:
-      grpc_chttp2_list_add_parsing_seen_stream(transport_parsing,
-                                               stream_parsing);
       if (cur == end) {
         return GRPC_ERROR_NONE;
       }
       uint32_t remaining = (uint32_t)(end - cur);
       if (remaining == p->frame_size) {
-        stream_parsing->stats.incoming.data_bytes += p->frame_size;
+        s->stats.incoming.data_bytes += p->frame_size;
         grpc_chttp2_incoming_byte_stream_push(
             exec_ctx, p->parsing_frame,
             gpr_slice_sub(slice, (size_t)(cur - beg), (size_t)(end - beg)));
         grpc_chttp2_incoming_byte_stream_finished(exec_ctx, p->parsing_frame,
-                                                  GRPC_ERROR_NONE, 1);
+                                                  GRPC_ERROR_NONE);
         p->parsing_frame = NULL;
         p->state = GRPC_CHTTP2_DATA_FH_0;
         return GRPC_ERROR_NONE;
       } else if (remaining > p->frame_size) {
-        stream_parsing->stats.incoming.data_bytes += p->frame_size;
+        s->stats.incoming.data_bytes += p->frame_size;
         grpc_chttp2_incoming_byte_stream_push(
             exec_ctx, p->parsing_frame,
             gpr_slice_sub(slice, (size_t)(cur - beg),
                           (size_t)(cur + p->frame_size - beg)));
         grpc_chttp2_incoming_byte_stream_finished(exec_ctx, p->parsing_frame,
-                                                  GRPC_ERROR_NONE, 1);
+                                                  GRPC_ERROR_NONE);
         p->parsing_frame = NULL;
         cur += p->frame_size;
         goto fh_0; /* loop */
@@ -272,10 +259,25 @@ grpc_error *grpc_chttp2_data_parser_parse(
             exec_ctx, p->parsing_frame,
             gpr_slice_sub(slice, (size_t)(cur - beg), (size_t)(end - beg)));
         p->frame_size -= remaining;
-        stream_parsing->stats.incoming.data_bytes += remaining;
+        s->stats.incoming.data_bytes += remaining;
         return GRPC_ERROR_NONE;
       }
   }
 
   GPR_UNREACHABLE_CODE(return GRPC_ERROR_CREATE("Should never reach here"));
 }
+
+grpc_error *grpc_chttp2_data_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
+                                          grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s,
+                                          gpr_slice slice, int is_last) {
+  grpc_chttp2_data_parser *p = parser;
+  grpc_error *error = parse_inner(exec_ctx, p, t, s, slice);
+
+  if (is_last && p->is_last_frame) {
+    grpc_chttp2_mark_stream_closed(exec_ctx, t, s, true, false,
+                                   GRPC_ERROR_NONE);
+  }
+
+  return error;
+}

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

@@ -69,7 +69,6 @@ typedef struct {
   grpc_error *error;
 
   int is_frame_compressed;
-  grpc_chttp2_incoming_frame_queue incoming_frames;
   grpc_chttp2_incoming_byte_stream *parsing_frame;
 } grpc_chttp2_data_parser;
 
@@ -92,10 +91,10 @@ grpc_error *grpc_chttp2_data_parser_begin_frame(grpc_chttp2_data_parser *parser,
 
 /* handle a slice of a data frame - is_last indicates the last slice of a
    frame */
-grpc_error *grpc_chttp2_data_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last);
+grpc_error *grpc_chttp2_data_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
+                                          grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s,
+                                          gpr_slice slice, int is_last);
 
 void grpc_chttp2_encode_data(uint32_t id, gpr_slice_buffer *inbuf,
                              uint32_t write_bytes, int is_eof,

src/core/ext/transport/chttp2/transport/frame_goaway.c

@@ -67,10 +67,11 @@ grpc_error *grpc_chttp2_goaway_parser_begin_frame(grpc_chttp2_goaway_parser *p,
   return GRPC_ERROR_NONE;
 }
 
-grpc_error *grpc_chttp2_goaway_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last) {
+grpc_error *grpc_chttp2_goaway_parser_parse(grpc_exec_ctx *exec_ctx,
+                                            void *parser,
+                                            grpc_chttp2_transport *t,
+                                            grpc_chttp2_stream *s,
+                                            gpr_slice slice, int is_last) {
   uint8_t *const beg = GPR_SLICE_START_PTR(slice);
   uint8_t *const end = GPR_SLICE_END_PTR(slice);
   uint8_t *cur = beg;
@@ -148,12 +149,9 @@ grpc_error *grpc_chttp2_goaway_parser_parse(
       p->debug_pos += (uint32_t)(end - cur);
       p->state = GRPC_CHTTP2_GOAWAY_DEBUG;
       if (is_last) {
-        transport_parsing->goaway_received = 1;
-        transport_parsing->goaway_last_stream_index = p->last_stream_id;
-        gpr_slice_unref(transport_parsing->goaway_text);
-        transport_parsing->goaway_error = (grpc_status_code)p->error_code;
-        transport_parsing->goaway_text =
-            gpr_slice_new(p->debug_data, p->debug_length, gpr_free);
+        grpc_chttp2_add_incoming_goaway(
+            exec_ctx, t, (uint32_t)p->error_code,
+            gpr_slice_new(p->debug_data, p->debug_length, gpr_free));
         p->debug_data = NULL;
       }
       return GRPC_ERROR_NONE;

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

@@ -65,10 +65,11 @@ void grpc_chttp2_goaway_parser_init(grpc_chttp2_goaway_parser *p);
 void grpc_chttp2_goaway_parser_destroy(grpc_chttp2_goaway_parser *p);
 grpc_error *grpc_chttp2_goaway_parser_begin_frame(
     grpc_chttp2_goaway_parser *parser, uint32_t length, uint8_t flags);
-grpc_error *grpc_chttp2_goaway_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last);
+grpc_error *grpc_chttp2_goaway_parser_parse(grpc_exec_ctx *exec_ctx,
+                                            void *parser,
+                                            grpc_chttp2_transport *t,
+                                            grpc_chttp2_stream *s,
+                                            gpr_slice slice, int is_last);
 
 void grpc_chttp2_goaway_append(uint32_t last_stream_id, uint32_t error_code,
                                gpr_slice debug_data,

src/core/ext/transport/chttp2/transport/frame_ping.c

@@ -73,10 +73,10 @@ grpc_error *grpc_chttp2_ping_parser_begin_frame(grpc_chttp2_ping_parser *parser,
   return GRPC_ERROR_NONE;
 }
 
-grpc_error *grpc_chttp2_ping_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last) {
+grpc_error *grpc_chttp2_ping_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
+                                          grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s,
+                                          gpr_slice slice, int is_last) {
   uint8_t *const beg = GPR_SLICE_START_PTR(slice);
   uint8_t *const end = GPR_SLICE_END_PTR(slice);
   uint8_t *cur = beg;
@@ -91,10 +91,11 @@ grpc_error *grpc_chttp2_ping_parser_parse(
   if (p->byte == 8) {
     GPR_ASSERT(is_last);
     if (p->is_ack) {
-      grpc_chttp2_ack_ping(exec_ctx, transport_parsing, p->opaque_8bytes);
+      grpc_chttp2_ack_ping(exec_ctx, t, p->opaque_8bytes);
     } else {
-      gpr_slice_buffer_add(&transport_parsing->qbuf,
+      gpr_slice_buffer_add(&t->qbuf,
                            grpc_chttp2_ping_create(1, p->opaque_8bytes));
+      grpc_chttp2_initiate_write(exec_ctx, t, false, "ping response");
     }
   }
 

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

@@ -48,9 +48,9 @@ gpr_slice grpc_chttp2_ping_create(uint8_t ack, uint8_t *opaque_8bytes);
 
 grpc_error *grpc_chttp2_ping_parser_begin_frame(grpc_chttp2_ping_parser *parser,
                                                 uint32_t length, uint8_t flags);
-grpc_error *grpc_chttp2_ping_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last);
+grpc_error *grpc_chttp2_ping_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
+                                          grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s,
+                                          gpr_slice slice, int is_last);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_FRAME_PING_H */

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

@@ -39,6 +39,8 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/transport/frame.h"
+#include "src/core/ext/transport/chttp2/transport/http2_errors.h"
+#include "src/core/ext/transport/chttp2/transport/status_conversion.h"
 
 gpr_slice grpc_chttp2_rst_stream_create(uint32_t id, uint32_t code,
                                         grpc_transport_one_way_stats *stats) {
@@ -83,10 +85,11 @@ grpc_error *grpc_chttp2_rst_stream_parser_begin_frame(
   return GRPC_ERROR_NONE;
 }
 
-grpc_error *grpc_chttp2_rst_stream_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last) {
+grpc_error *grpc_chttp2_rst_stream_parser_parse(grpc_exec_ctx *exec_ctx,
+                                                void *parser,
+                                                grpc_chttp2_transport *t,
+                                                grpc_chttp2_stream *s,
+                                                gpr_slice slice, int is_last) {
   uint8_t *const beg = GPR_SLICE_START_PTR(slice);
   uint8_t *const end = GPR_SLICE_END_PTR(slice);
   uint8_t *cur = beg;
@@ -97,19 +100,28 @@ grpc_error *grpc_chttp2_rst_stream_parser_parse(
     cur++;
     p->byte++;
   }
-  stream_parsing->stats.incoming.framing_bytes += (uint64_t)(end - cur);
+  s->stats.incoming.framing_bytes += (uint64_t)(end - cur);
 
   if (p->byte == 4) {
     GPR_ASSERT(is_last);
-    stream_parsing->received_close = 1;
-    if (stream_parsing->forced_close_error == GRPC_ERROR_NONE) {
-      stream_parsing->forced_close_error = grpc_error_set_int(
-          GRPC_ERROR_CREATE("RST_STREAM"), GRPC_ERROR_INT_HTTP2_ERROR,
-          (intptr_t)((((uint32_t)p->reason_bytes[0]) << 24) |
-                     (((uint32_t)p->reason_bytes[1]) << 16) |
-                     (((uint32_t)p->reason_bytes[2]) << 8) |
-                     (((uint32_t)p->reason_bytes[3]))));
+    uint32_t reason = (((uint32_t)p->reason_bytes[0]) << 24) |
+                      (((uint32_t)p->reason_bytes[1]) << 16) |
+                      (((uint32_t)p->reason_bytes[2]) << 8) |
+                      (((uint32_t)p->reason_bytes[3]));
+    grpc_error *error = GRPC_ERROR_NONE;
+    if (reason != GRPC_CHTTP2_NO_ERROR) {
+      error = grpc_error_set_int(GRPC_ERROR_CREATE("RST_STREAM"),
+                                 GRPC_ERROR_INT_HTTP2_ERROR, reason);
+      grpc_status_code status_code = grpc_chttp2_http2_error_to_grpc_status(
+          (grpc_chttp2_error_code)reason, s->deadline);
+      char *status_details;
+      gpr_asprintf(&status_details, "Received RST_STREAM with error code %d",
+                   reason);
+      gpr_slice slice_details = gpr_slice_from_copied_string(status_details);
+      gpr_free(status_details);
+      grpc_chttp2_fake_status(exec_ctx, t, s, status_code, &slice_details);
     }
+    grpc_chttp2_mark_stream_closed(exec_ctx, t, s, true, true, error);
   }
 
   return GRPC_ERROR_NONE;

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

@@ -49,9 +49,10 @@ gpr_slice grpc_chttp2_rst_stream_create(uint32_t stream_id, uint32_t code,
 
 grpc_error *grpc_chttp2_rst_stream_parser_begin_frame(
     grpc_chttp2_rst_stream_parser *parser, uint32_t length, uint8_t flags);
-grpc_error *grpc_chttp2_rst_stream_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last);
+grpc_error *grpc_chttp2_rst_stream_parser_parse(grpc_exec_ctx *exec_ctx,
+                                                void *parser,
+                                                grpc_chttp2_transport *t,
+                                                grpc_chttp2_stream *s,
+                                                gpr_slice slice, int is_last);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_FRAME_RST_STREAM_H */

src/core/ext/transport/chttp2/transport/frame_settings.c

@@ -143,10 +143,10 @@ grpc_error *grpc_chttp2_settings_parser_begin_frame(
   }
 }
 
-grpc_error *grpc_chttp2_settings_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *p,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last) {
+grpc_error *grpc_chttp2_settings_parser_parse(grpc_exec_ctx *exec_ctx, void *p,
+                                              grpc_chttp2_transport *t,
+                                              grpc_chttp2_stream *s,
+                                              gpr_slice slice, int is_last) {
   grpc_chttp2_settings_parser *parser = p;
   const uint8_t *cur = GPR_SLICE_START_PTR(slice);
   const uint8_t *end = GPR_SLICE_END_PTR(slice);
@@ -162,11 +162,9 @@ grpc_error *grpc_chttp2_settings_parser_parse(
         if (cur == end) {
           parser->state = GRPC_CHTTP2_SPS_ID0;
           if (is_last) {
-            transport_parsing->settings_updated = 1;
             memcpy(parser->target_settings, parser->incoming_settings,
                    GRPC_CHTTP2_NUM_SETTINGS * sizeof(uint32_t));
-            gpr_slice_buffer_add(&transport_parsing->qbuf,
-                                 grpc_chttp2_settings_ack_create());
+            gpr_slice_buffer_add(&t->qbuf, grpc_chttp2_settings_ack_create());
           }
           return GRPC_ERROR_NONE;
         }
@@ -226,9 +224,9 @@ grpc_error *grpc_chttp2_settings_parser_parse(
                 break;
               case GRPC_CHTTP2_DISCONNECT_ON_INVALID_VALUE:
                 grpc_chttp2_goaway_append(
-                    transport_parsing->last_incoming_stream_id, sp->error_value,
+                    t->last_new_stream_id, sp->error_value,
                     gpr_slice_from_static_string("HTTP2 settings error"),
-                    &transport_parsing->qbuf);
+                    &t->qbuf);
                 gpr_asprintf(&msg, "invalid value %u passed for %s",
                              parser->value, sp->name);
                 grpc_error *err = GRPC_ERROR_CREATE(msg);
@@ -238,18 +236,17 @@ grpc_error *grpc_chttp2_settings_parser_parse(
           }
           if (parser->id == GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE &&
               parser->incoming_settings[parser->id] != parser->value) {
-            transport_parsing->initial_window_update =
+            t->initial_window_update =
                 (int64_t)parser->value - parser->incoming_settings[parser->id];
             if (grpc_http_trace) {
               gpr_log(GPR_DEBUG, "adding %d for initial_window change",
-                      (int)transport_parsing->initial_window_update);
+                      (int)t->initial_window_update);
             }
           }
           parser->incoming_settings[parser->id] = parser->value;
           if (grpc_http_trace) {
             gpr_log(GPR_DEBUG, "CHTTP2:%s: got setting %d = %d",
-                    transport_parsing->is_client ? "CLI" : "SVR", parser->id,
-                    parser->value);
+                    t->is_client ? "CLI" : "SVR", parser->id, parser->value);
           }
         } else if (grpc_http_trace) {
           gpr_log(GPR_ERROR, "CHTTP2: Ignoring unknown setting %d (value %d)",

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

@@ -95,9 +95,10 @@ gpr_slice grpc_chttp2_settings_ack_create(void);
 grpc_error *grpc_chttp2_settings_parser_begin_frame(
     grpc_chttp2_settings_parser *parser, uint32_t length, uint8_t flags,
     uint32_t *settings);
-grpc_error *grpc_chttp2_settings_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last);
+grpc_error *grpc_chttp2_settings_parser_parse(grpc_exec_ctx *exec_ctx,
+                                              void *parser,
+                                              grpc_chttp2_transport *t,
+                                              grpc_chttp2_stream *s,
+                                              gpr_slice slice, int is_last);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_FRAME_SETTINGS_H */

src/core/ext/transport/chttp2/transport/frame_window_update.c

@@ -80,9 +80,8 @@ grpc_error *grpc_chttp2_window_update_parser_begin_frame(
 }
 
 grpc_error *grpc_chttp2_window_update_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last) {
+    grpc_exec_ctx *exec_ctx, void *parser, grpc_chttp2_transport *t,
+    grpc_chttp2_stream *s, gpr_slice slice, int is_last) {
   uint8_t *const beg = GPR_SLICE_START_PTR(slice);
   uint8_t *const end = GPR_SLICE_END_PTR(slice);
   uint8_t *cur = beg;
@@ -94,8 +93,8 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
     p->byte++;
   }
 
-  if (stream_parsing != NULL) {
-    stream_parsing->stats.incoming.framing_bytes += (uint32_t)(end - cur);
+  if (s != NULL) {
+    s->stats.incoming.framing_bytes += (uint32_t)(end - cur);
   }
 
   if (p->byte == 4) {
@@ -109,17 +108,26 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
     }
     GPR_ASSERT(is_last);
 
-    if (transport_parsing->incoming_stream_id != 0) {
-      if (stream_parsing != NULL) {
-        GRPC_CHTTP2_FLOW_CREDIT_STREAM("parse", transport_parsing,
-                                       stream_parsing, outgoing_window,
+    if (t->incoming_stream_id != 0) {
+      if (s != NULL) {
+        bool was_zero = s->outgoing_window <= 0;
+        GRPC_CHTTP2_FLOW_CREDIT_STREAM("parse", t, s, outgoing_window,
                                        received_update);
-        grpc_chttp2_list_add_parsing_seen_stream(transport_parsing,
-                                                 stream_parsing);
+        bool is_zero = s->outgoing_window <= 0;
+        if (was_zero && !is_zero) {
+          grpc_chttp2_become_writable(exec_ctx, t, s, false,
+                                      "stream.read_flow_control");
+        }
       }
     } else {
-      GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parse", transport_parsing,
-                                        outgoing_window, received_update);
+      bool was_zero = t->outgoing_window <= 0;
+      GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parse", t, outgoing_window,
+                                        received_update);
+      bool is_zero = t->outgoing_window <= 0;
+      if (was_zero && !is_zero) {
+        grpc_chttp2_initiate_write(exec_ctx, t, false,
+                                   "new_global_flow_control");
+      }
     }
   }
 

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

@@ -51,8 +51,7 @@ gpr_slice grpc_chttp2_window_update_create(uint32_t id, uint32_t window_delta,
 grpc_error *grpc_chttp2_window_update_parser_begin_frame(
     grpc_chttp2_window_update_parser *parser, uint32_t length, uint8_t flags);
 grpc_error *grpc_chttp2_window_update_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last);
+    grpc_exec_ctx *exec_ctx, void *parser, grpc_chttp2_transport *t,
+    grpc_chttp2_stream *s, gpr_slice slice, int is_last);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_FRAME_WINDOW_UPDATE_H */

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

@@ -45,7 +45,8 @@
 typedef struct grpc_chttp2_hpack_parser grpc_chttp2_hpack_parser;
 
 typedef grpc_error *(*grpc_chttp2_hpack_parser_state)(
-    grpc_chttp2_hpack_parser *p, const uint8_t *beg, const uint8_t *end);
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_hpack_parser *p, const uint8_t *beg,
+    const uint8_t *end);
 
 typedef struct {
   char *str;
@@ -55,7 +56,7 @@ typedef struct {
 
 struct grpc_chttp2_hpack_parser {
   /* user specified callback for each header output */
-  void (*on_header)(void *user_data, grpc_mdelem *md);
+  void (*on_header)(grpc_exec_ctx *exec_ctx, void *user_data, grpc_mdelem *md);
   void *on_header_user_data;
 
   grpc_error *last_error;
@@ -104,15 +105,17 @@ void grpc_chttp2_hpack_parser_destroy(grpc_chttp2_hpack_parser *p);
 void grpc_chttp2_hpack_parser_set_has_priority(grpc_chttp2_hpack_parser *p);
 
 /* returns 1 on success, 0 on error */
-grpc_error *grpc_chttp2_hpack_parser_parse(grpc_chttp2_hpack_parser *p,
+grpc_error *grpc_chttp2_hpack_parser_parse(grpc_exec_ctx *exec_ctx,
+                                           grpc_chttp2_hpack_parser *p,
                                            const uint8_t *beg,
                                            const uint8_t *end);
 
 /* wraps grpc_chttp2_hpack_parser_parse to provide a frame level parser for
    the transport */
-grpc_error *grpc_chttp2_header_parser_parse(
-    grpc_exec_ctx *exec_ctx, void *hpack_parser,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last);
+grpc_error *grpc_chttp2_header_parser_parse(grpc_exec_ctx *exec_ctx,
+                                            void *hpack_parser,
+                                            grpc_chttp2_transport *t,
+                                            grpc_chttp2_stream *s,
+                                            gpr_slice slice, int is_last);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_HPACK_PARSER_H */

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

@@ -48,35 +48,30 @@
 #include "src/core/ext/transport/chttp2/transport/hpack_parser.h"
 #include "src/core/ext/transport/chttp2/transport/incoming_metadata.h"
 #include "src/core/ext/transport/chttp2/transport/stream_map.h"
+#include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/endpoint.h"
 #include "src/core/lib/transport/connectivity_state.h"
 #include "src/core/lib/transport/transport_impl.h"
 
-typedef struct grpc_chttp2_transport grpc_chttp2_transport;
-typedef struct grpc_chttp2_stream grpc_chttp2_stream;
-
 /* streams are kept in various linked lists depending on what things need to
    happen to them... this enum labels each list */
 typedef enum {
-  GRPC_CHTTP2_LIST_ALL_STREAMS,
-  GRPC_CHTTP2_LIST_CHECK_READ_OPS,
-  GRPC_CHTTP2_LIST_UNANNOUNCED_INCOMING_WINDOW_AVAILABLE,
   GRPC_CHTTP2_LIST_WRITABLE,
   GRPC_CHTTP2_LIST_WRITING,
-  GRPC_CHTTP2_LIST_WRITTEN,
-  GRPC_CHTTP2_LIST_PARSING_SEEN,
-  GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_PARSING,
-  GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_WRITING,
   GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT,
-  /* streams waiting for the outgoing window in the writing path, they will be
-   * merged to the stalled list or writable list under transport lock. */
-  GRPC_CHTTP2_LIST_WRITING_STALLED_BY_TRANSPORT,
   /** streams that are waiting to start because there are too many concurrent
       streams on the connection */
   GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY,
   STREAM_LIST_COUNT /* must be last */
 } grpc_chttp2_stream_list_id;
 
+typedef enum {
+  GRPC_CHTTP2_WRITE_STATE_IDLE,
+  GRPC_CHTTP2_WRITE_STATE_WRITING,
+  GRPC_CHTTP2_WRITE_STATE_WRITING_WITH_MORE,
+  GRPC_CHTTP2_WRITE_STATE_WRITING_WITH_MORE_AND_COVERED_BY_POLLER,
+} grpc_chttp2_write_state;
+
 /* deframer state for the overall http2 stream of bytes */
 typedef enum {
   /* prefix: one entry per http2 connection prefix byte */
@@ -151,6 +146,12 @@ typedef struct grpc_chttp2_outstanding_ping {
   struct grpc_chttp2_outstanding_ping *prev;
 } grpc_chttp2_outstanding_ping;
 
+typedef struct grpc_chttp2_write_cb {
+  size_t call_at_byte;
+  grpc_closure *closure;
+  struct grpc_chttp2_write_cb *next;
+} grpc_chttp2_write_cb;
+
 /* forward declared in frame_data.h */
 struct grpc_chttp2_incoming_byte_stream {
   grpc_byte_stream base;
@@ -160,18 +161,86 @@ struct grpc_chttp2_incoming_byte_stream {
 
   grpc_chttp2_transport *transport;
   grpc_chttp2_stream *stream;
-  int is_tail;
+  bool is_tail;
+
+  gpr_mu slice_mu;  // protects slices, on_next
   gpr_slice_buffer slices;
   grpc_closure *on_next;
   gpr_slice *next;
+  uint32_t remaining_bytes;
+
+  struct {
+    grpc_closure closure;
+    gpr_slice *slice;
+    size_t max_size_hint;
+    grpc_closure *on_complete;
+  } next_action;
+  grpc_closure destroy_action;
+  grpc_closure finished_action;
 };
 
-typedef struct {
+struct grpc_chttp2_transport {
+  grpc_transport base; /* must be first */
+  gpr_refcount refs;
+  grpc_endpoint *ep;
+  char *peer_string;
+
+  grpc_combiner *combiner;
+
+  /** write execution state of the transport */
+  grpc_chttp2_write_state write_state;
+
+  /** is the transport destroying itself? */
+  uint8_t destroying;
+  /** has the upper layer closed the transport? */
+  uint8_t closed;
+
+  /** is there a read request to the endpoint outstanding? */
+  uint8_t endpoint_reading;
+
+  /** various lists of streams */
+  grpc_chttp2_stream_list lists[STREAM_LIST_COUNT];
+
+  /** maps stream id to grpc_chttp2_stream objects */
+  grpc_chttp2_stream_map stream_map;
+
+  grpc_closure write_action_begin_locked;
+  grpc_closure write_action;
+  grpc_closure write_action_end;
+  grpc_closure write_action_end_locked;
+
+  grpc_closure read_action_begin;
+  grpc_closure read_action_locked;
+
+  /** incoming read bytes */
+  gpr_slice_buffer read_buffer;
+
+  /** address to place a newly accepted stream - set and unset by
+      grpc_chttp2_parsing_accept_stream; used by init_stream to
+      publish the accepted server stream */
+  grpc_chttp2_stream **accepting_stream;
+
+  struct {
+    /* accept stream callback */
+    void (*accept_stream)(grpc_exec_ctx *exec_ctx, void *user_data,
+                          grpc_transport *transport, const void *server_data);
+    void *accept_stream_user_data;
+
+    /** connectivity tracking */
+    grpc_connectivity_state_tracker state_tracker;
+  } channel_callback;
+
+  /** data to write now */
+  gpr_slice_buffer outbuf;
+  /** hpack encoding */
+  grpc_chttp2_hpack_compressor hpack_compressor;
+  int64_t outgoing_window;
+  /** is this a client? */
+  uint8_t is_client;
+
   /** data to write next write */
   gpr_slice_buffer qbuf;
 
-  /** window available for us to send to peer */
-  int64_t outgoing_window;
   /** window available to announce to peer */
   int64_t announce_incoming_window;
   /** how much window would we like to have for incoming_window */
@@ -182,8 +251,6 @@ typedef struct {
   /** have we sent a goaway */
   uint8_t sent_goaway;
 
-  /** is this transport a client? */
-  uint8_t is_client;
   /** are the local settings dirty and need to be sent? */
   uint8_t dirtied_local_settings;
   /** have local settings been sent? */
@@ -200,49 +267,14 @@ typedef struct {
   /** how far to lookahead in a stream? */
   uint32_t stream_lookahead;
 
-  /** last received stream id */
-  uint32_t last_incoming_stream_id;
+  /** last new stream id */
+  uint32_t last_new_stream_id;
 
   /** pings awaiting responses */
   grpc_chttp2_outstanding_ping pings;
   /** next payload for an outgoing ping */
   uint64_t ping_counter;
 
-  /** concurrent stream count: updated when not parsing,
-      so this is a strict over-estimation on the client */
-  uint32_t concurrent_stream_count;
-} grpc_chttp2_transport_global;
-
-typedef struct {
-  /** data to write now */
-  gpr_slice_buffer outbuf;
-  /** hpack encoding */
-  grpc_chttp2_hpack_compressor hpack_compressor;
-  int64_t outgoing_window;
-  /** is this a client? */
-  uint8_t is_client;
-  /** callback for when writing is done */
-  grpc_closure done_cb;
-  /** maximum frame size */
-  uint32_t max_frame_size;
-} grpc_chttp2_transport_writing;
-
-struct grpc_chttp2_transport_parsing {
-  /** is this transport a client? (boolean) */
-  uint8_t is_client;
-
-  /** were settings updated? */
-  uint8_t settings_updated;
-  /** was a settings ack received? */
-  uint8_t settings_ack_received;
-  /** was a goaway frame received? */
-  uint8_t goaway_received;
-
-  /** initial window change */
-  int64_t initial_window_update;
-
-  /** data to write later - after parsing */
-  gpr_slice_buffer qbuf;
   /** parser for headers */
   grpc_chttp2_hpack_parser hpack_parser;
   /** simple one shot parsers */
@@ -255,13 +287,12 @@ struct grpc_chttp2_transport_parsing {
   /** parser for goaway frames */
   grpc_chttp2_goaway_parser goaway_parser;
 
+  /** initial window change */
+  int64_t initial_window_update;
+
   /** window available for peer to send to us */
   int64_t incoming_window;
 
-  /** next stream id available at the time of beginning parsing */
-  uint32_t next_stream_id;
-  uint32_t last_incoming_stream_id;
-
   /* deframing */
   grpc_chttp2_deframe_transport_state deframe_state;
   uint8_t incoming_frame_type;
@@ -272,142 +303,38 @@ struct grpc_chttp2_transport_parsing {
   uint32_t incoming_frame_size;
   uint32_t incoming_stream_id;
 
-  /* current max frame size */
-  uint32_t max_frame_size;
-
   /* active parser */
   void *parser_data;
-  grpc_chttp2_stream_parsing *incoming_stream;
+  grpc_chttp2_stream *incoming_stream;
   grpc_error *(*parser)(grpc_exec_ctx *exec_ctx, void *parser_user_data,
-                        grpc_chttp2_transport_parsing *transport_parsing,
-                        grpc_chttp2_stream_parsing *stream_parsing,
+                        grpc_chttp2_transport *t, grpc_chttp2_stream *s,
                         gpr_slice slice, int is_last);
 
-  /* received settings */
-  uint32_t settings[GRPC_CHTTP2_NUM_SETTINGS];
-  /* last settings that were sent */
-  uint32_t last_sent_settings[GRPC_CHTTP2_NUM_SETTINGS];
-
   /* goaway data */
   grpc_status_code goaway_error;
   uint32_t goaway_last_stream_index;
   gpr_slice goaway_text;
 
-  int64_t outgoing_window;
+  grpc_chttp2_write_cb *write_cb_pool;
 };
 
-typedef void (*grpc_chttp2_locked_action)(grpc_exec_ctx *ctx,
-                                          grpc_chttp2_transport *t,
-                                          grpc_chttp2_stream *s, void *arg);
-
-typedef struct grpc_chttp2_executor_action_header {
-  grpc_chttp2_stream *stream;
-  grpc_chttp2_locked_action action;
-  struct grpc_chttp2_executor_action_header *next;
-  void *arg;
-} grpc_chttp2_executor_action_header;
-
 typedef enum {
-  /** no writing activity */
-  GRPC_CHTTP2_WRITING_INACTIVE,
-  /** write has been requested, but not scheduled yet */
-  GRPC_CHTTP2_WRITE_REQUESTED_WITH_POLLER,
-  GRPC_CHTTP2_WRITE_REQUESTED_NO_POLLER,
-  /** write has been requested and scheduled against the workqueue */
-  GRPC_CHTTP2_WRITE_SCHEDULED,
-  /** write has been initiated after being reaped from the workqueue */
-  GRPC_CHTTP2_WRITING,
-  /** write has been initiated, AND another write needs to be started once it's
-      done */
-  GRPC_CHTTP2_WRITING_STALE_WITH_POLLER,
-  GRPC_CHTTP2_WRITING_STALE_NO_POLLER,
-} grpc_chttp2_write_state;
-
-struct grpc_chttp2_transport {
-  grpc_transport base; /* must be first */
-  gpr_refcount refs;
-  grpc_endpoint *ep;
-  char *peer_string;
-
-  /** when this drops to zero it's safe to shutdown the endpoint */
-  gpr_refcount shutdown_ep_refs;
-
-  struct {
-    gpr_mu mu;
-
-    /** is a thread currently in the global lock */
-    bool global_active;
-    /** is a thread currently parsing */
-    bool parsing_active;
-    /** write execution state of the transport */
-    grpc_chttp2_write_state write_state;
+  GRPC_METADATA_NOT_PUBLISHED,
+  GRPC_METADATA_SYNTHESIZED_FROM_FAKE,
+  GRPC_METADATA_PUBLISHED_FROM_WIRE,
+  GPRC_METADATA_PUBLISHED_AT_CLOSE
+} grpc_published_metadata_method;
 
-    grpc_chttp2_executor_action_header *pending_actions_head;
-    grpc_chttp2_executor_action_header *pending_actions_tail;
-  } executor;
-
-  /** is the transport destroying itself? */
-  uint8_t destroying;
-  /** has the upper layer closed the transport? */
-  uint8_t closed;
-
-  /** is there a read request to the endpoint outstanding? */
-  uint8_t endpoint_reading;
-
-  /** various lists of streams */
-  grpc_chttp2_stream_list lists[STREAM_LIST_COUNT];
-
-  /** global state for reading/writing */
-  grpc_chttp2_transport_global global;
-  /** state only accessible by the chain of execution that
-      set writing_state >= GRPC_WRITING, and only by the writing closure
-      chain. */
-  grpc_chttp2_transport_writing writing;
-  /** state only accessible by the chain of execution that
-      set parsing_active=1 */
-  grpc_chttp2_transport_parsing parsing;
-
-  /** maps stream id to grpc_chttp2_stream objects;
-      owned by the parsing thread when parsing */
-  grpc_chttp2_stream_map parsing_stream_map;
-
-  /** streams created by the client (possibly during parsing);
-      merged with parsing_stream_map during unlock when no
-      parsing is occurring */
-  grpc_chttp2_stream_map new_stream_map;
-
-  /** closure to execute writing */
-  grpc_closure writing_action;
-  /** closure to start reading from the endpoint */
-  grpc_closure reading_action;
-  /** closure to actually do parsing */
-  grpc_closure parsing_action;
-  /** closure to initiate writing */
-  grpc_closure initiate_writing;
-
-  /** incoming read bytes */
-  gpr_slice_buffer read_buffer;
-
-  /** address to place a newly accepted stream - set and unset by
-      grpc_chttp2_parsing_accept_stream; used by init_stream to
-      publish the accepted server stream */
-  grpc_chttp2_stream **accepting_stream;
-
-  struct {
-    /* accept stream callback */
-    void (*accept_stream)(grpc_exec_ctx *exec_ctx, void *user_data,
-                          grpc_transport *transport, const void *server_data);
-    void *accept_stream_user_data;
+struct grpc_chttp2_stream {
+  grpc_chttp2_transport *t;
+  grpc_stream_refcount *refcount;
 
-    /** connectivity tracking */
-    grpc_connectivity_state_tracker state_tracker;
-  } channel_callback;
+  grpc_closure destroy_stream;
+  void *destroy_stream_arg;
 
-  /** Transport op to be applied post-parsing */
-  grpc_transport_op *post_parsing_op;
-};
+  grpc_chttp2_stream_link links[STREAM_LIST_COUNT];
+  uint8_t included[STREAM_LIST_COUNT];
 
-typedef struct {
   /** HTTP2 stream id for this stream, or zero if one has not been assigned */
   uint32_t id;
 
@@ -417,20 +344,21 @@ typedef struct {
       As the upper layer offers more bytes, this value increases.
       As bytes are read, this value decreases. */
   uint32_t max_recv_bytes;
-  /** The number of bytes the upper layer has offered to read but we have
-      not yet announced to HTTP2 flow control.
-      As the upper layers offer to read more bytes, this value increases.
-      As we advertise incoming flow control window, this value decreases. */
-  uint32_t unannounced_incoming_window_for_parse;
-  uint32_t unannounced_incoming_window_for_writing;
   /** things the upper layers would like to send */
   grpc_metadata_batch *send_initial_metadata;
   grpc_closure *send_initial_metadata_finished;
-  grpc_byte_stream *send_message;
-  grpc_closure *send_message_finished;
   grpc_metadata_batch *send_trailing_metadata;
   grpc_closure *send_trailing_metadata_finished;
 
+  grpc_byte_stream *fetching_send_message;
+  uint32_t fetched_send_message_length;
+  gpr_slice fetching_slice;
+  int64_t fetching_slice_end_offset;
+  bool complete_fetch_covered_by_poller;
+  grpc_closure complete_fetch;
+  grpc_closure complete_fetch_locked;
+  grpc_closure *fetching_send_message_finished;
+
   grpc_metadata_batch *recv_initial_metadata;
   grpc_closure *recv_initial_metadata_ready;
   grpc_byte_stream **recv_message;
@@ -450,90 +378,44 @@ typedef struct {
   bool read_closed;
   /** Are all published incoming byte streams closed. */
   bool all_incoming_byte_streams_finished;
-  /** Is this stream in the stream map. */
-  bool in_stream_map;
   /** Has this stream seen an error.
       If true, then pending incoming frames can be thrown away. */
   bool seen_error;
-  bool exceeded_metadata_size;
 
   /** the error that resulted in this stream being read-closed */
   grpc_error *read_closed_error;
   /** the error that resulted in this stream being write-closed */
   grpc_error *write_closed_error;
 
-  bool published_initial_metadata;
-  bool published_trailing_metadata;
+  grpc_published_metadata_method published_metadata[2];
   bool final_metadata_requested;
 
-  grpc_chttp2_incoming_metadata_buffer received_initial_metadata;
-  grpc_chttp2_incoming_metadata_buffer received_trailing_metadata;
+  grpc_chttp2_incoming_metadata_buffer metadata_buffer[2];
 
   grpc_chttp2_incoming_frame_queue incoming_frames;
 
   gpr_timespec deadline;
-} grpc_chttp2_stream_global;
-
-typedef struct {
-  /** HTTP2 stream id for this stream, or zero if one has not been assigned */
-  uint32_t id;
-  uint8_t fetching;
-  bool sent_initial_metadata;
-  uint8_t sent_message;
-  uint8_t sent_trailing_metadata;
-  uint8_t read_closed;
-  /** send this initial metadata */
-  grpc_metadata_batch *send_initial_metadata;
-  grpc_byte_stream *send_message;
-  grpc_metadata_batch *send_trailing_metadata;
-  int64_t outgoing_window;
-  /** how much window should we announce? */
-  uint32_t announce_window;
-  gpr_slice_buffer flow_controlled_buffer;
-  gpr_slice fetching_slice;
-  size_t stream_fetched;
-  grpc_closure finished_fetch;
-  /** stats gathered during the write */
-  grpc_transport_one_way_stats stats;
-} grpc_chttp2_stream_writing;
 
-struct grpc_chttp2_stream_parsing {
   /** saw some stream level error */
   grpc_error *forced_close_error;
-  /** HTTP2 stream id for this stream, or zero if one has not been assigned */
-  uint32_t id;
-  /** has this stream received a close */
-  uint8_t received_close;
   /** how many header frames have we received? */
   uint8_t header_frames_received;
-  /** which metadata did we get (on this parse) */
-  uint8_t got_metadata_on_parse[2];
-  /** should we raise the seen_error flag in transport_global */
-  bool seen_error;
-  bool exceeded_metadata_size;
   /** window available for peer to send to us */
   int64_t incoming_window;
   /** parsing state for data frames */
   grpc_chttp2_data_parser data_parser;
-  /** amount of window given */
-  int64_t outgoing_window;
   /** number of bytes received - reset at end of parse thread execution */
   int64_t received_bytes;
-  /** stats gathered during the parse */
-  grpc_transport_stream_stats stats;
-
-  /** incoming metadata */
-  grpc_chttp2_incoming_metadata_buffer metadata_buffer[2];
-};
 
-struct grpc_chttp2_stream {
-  grpc_stream_refcount *refcount;
-  grpc_chttp2_stream_global global;
-  grpc_chttp2_stream_writing writing;
-  grpc_chttp2_stream_parsing parsing;
+  bool sent_initial_metadata;
+  bool sent_trailing_metadata;
+  /** how much window should we announce? */
+  uint32_t announce_window;
+  gpr_slice_buffer flow_controlled_buffer;
 
-  grpc_chttp2_stream_link links[STREAM_LIST_COUNT];
-  uint8_t included[STREAM_LIST_COUNT];
+  grpc_chttp2_write_cb *on_write_finished_cbs;
+  grpc_chttp2_write_cb *finish_after_write;
+  size_t sending_bytes;
 };
 
 /** Transport writing call flow:
@@ -549,168 +431,71 @@ struct grpc_chttp2_stream {
     The actual call chain is documented in the implementation of this function.
     */
 void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
-                                grpc_chttp2_transport_global *transport_global,
+                                grpc_chttp2_transport *t,
                                 bool covered_by_poller, const char *reason);
 
 /** Someone is unlocking the transport mutex: check to see if writes
-    are required, and schedule them if so */
-int grpc_chttp2_unlocking_check_writes(grpc_exec_ctx *exec_ctx,
-                                       grpc_chttp2_transport_global *global,
-                                       grpc_chttp2_transport_writing *writing);
-void grpc_chttp2_perform_writes(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_writing *transport_writing,
-    grpc_endpoint *endpoint);
-void grpc_chttp2_terminate_writing(grpc_exec_ctx *exec_ctx,
-                                   void *transport_writing, grpc_error *error);
-void grpc_chttp2_cleanup_writing(grpc_exec_ctx *exec_ctx,
-                                 grpc_chttp2_transport_global *global,
-                                 grpc_chttp2_transport_writing *writing);
-
-void grpc_chttp2_prepare_to_read(grpc_chttp2_transport_global *global,
-                                 grpc_chttp2_transport_parsing *parsing);
+    are required, and frame them if so */
+bool grpc_chttp2_begin_write(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t);
+void grpc_chttp2_end_write(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+                           grpc_error *error);
+
 /** Process one slice of incoming data; return 1 if the connection is still
     viable after reading, or 0 if the connection should be torn down */
-grpc_error *grpc_chttp2_perform_read(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    gpr_slice slice);
-void grpc_chttp2_publish_reads(grpc_exec_ctx *exec_ctx,
-                               grpc_chttp2_transport_global *global,
-                               grpc_chttp2_transport_parsing *parsing);
-
-bool grpc_chttp2_list_add_writable_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
+grpc_error *grpc_chttp2_perform_read(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_transport *t, gpr_slice slice);
+
+bool grpc_chttp2_list_add_writable_stream(grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s);
 /** Get a writable stream
     returns non-zero if there was a stream available */
-int grpc_chttp2_list_pop_writable_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_writing **stream_writing);
+int grpc_chttp2_list_pop_writable_stream(grpc_chttp2_transport *t,
+                                         grpc_chttp2_stream **s);
 bool grpc_chttp2_list_remove_writable_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) GRPC_MUST_USE_RESULT;
-
-void grpc_chttp2_list_add_writing_stream(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing);
-int grpc_chttp2_list_have_writing_streams(
-    grpc_chttp2_transport_writing *transport_writing);
-int grpc_chttp2_list_pop_writing_stream(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing **stream_writing);
-
-void grpc_chttp2_list_add_written_stream(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing);
-int grpc_chttp2_list_pop_written_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_writing **stream_writing);
-
-void grpc_chttp2_list_add_parsing_seen_stream(
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing);
-int grpc_chttp2_list_pop_parsing_seen_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_parsing **stream_parsing);
-
-void grpc_chttp2_list_add_waiting_for_concurrency(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-int grpc_chttp2_list_pop_waiting_for_concurrency(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global);
-
-void grpc_chttp2_list_add_check_read_ops(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-bool grpc_chttp2_list_remove_check_read_ops(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-int grpc_chttp2_list_pop_check_read_ops(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global);
-
-void grpc_chttp2_list_add_writing_stalled_by_transport(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing);
-bool grpc_chttp2_list_flush_writing_stalled_by_transport(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_writing *transport_writing);
-
-void grpc_chttp2_list_add_stalled_by_transport(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing);
-int grpc_chttp2_list_pop_stalled_by_transport(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global);
-void grpc_chttp2_list_remove_stalled_by_transport(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-
-void grpc_chttp2_list_add_unannounced_incoming_window_available(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-void grpc_chttp2_list_remove_unannounced_incoming_window_available(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-int grpc_chttp2_list_pop_unannounced_incoming_window_available(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_parsing **stream_parsing);
-
-void grpc_chttp2_list_add_closed_waiting_for_parsing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-int grpc_chttp2_list_pop_closed_waiting_for_parsing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global);
-
-void grpc_chttp2_list_add_closed_waiting_for_writing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global);
-int grpc_chttp2_list_pop_closed_waiting_for_writing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global);
-
-grpc_chttp2_stream_parsing *grpc_chttp2_parsing_lookup_stream(
-    grpc_chttp2_transport_parsing *transport_parsing, uint32_t id);
-grpc_chttp2_stream_parsing *grpc_chttp2_parsing_accept_stream(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    uint32_t id);
-
-void grpc_chttp2_add_incoming_goaway(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
-    uint32_t goaway_error, gpr_slice goaway_text);
-
-void grpc_chttp2_register_stream(grpc_chttp2_transport *t,
-                                 grpc_chttp2_stream *s);
-/* returns 1 if this is the last stream, 0 otherwise */
-int grpc_chttp2_unregister_stream(grpc_chttp2_transport *t,
-                                  grpc_chttp2_stream *s) GRPC_MUST_USE_RESULT;
-int grpc_chttp2_has_streams(grpc_chttp2_transport *t);
-void grpc_chttp2_for_all_streams(
-    grpc_chttp2_transport_global *transport_global, void *user_data,
-    void (*cb)(grpc_chttp2_transport_global *transport_global, void *user_data,
-               grpc_chttp2_stream_global *stream_global));
-
-void grpc_chttp2_parsing_become_skip_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-
-void grpc_chttp2_complete_closure_step(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global, grpc_closure **pclosure,
-    grpc_error *error);
-
-void grpc_chttp2_run_with_global_lock(grpc_exec_ctx *exec_ctx,
-                                      grpc_chttp2_transport *transport,
-                                      grpc_chttp2_stream *optional_stream,
-                                      grpc_chttp2_locked_action action,
-                                      void *arg, size_t sizeof_arg);
+    grpc_chttp2_transport *t, grpc_chttp2_stream *s) GRPC_MUST_USE_RESULT;
+
+bool grpc_chttp2_list_add_writing_stream(grpc_chttp2_transport *t,
+                                         grpc_chttp2_stream *s);
+int grpc_chttp2_list_have_writing_streams(grpc_chttp2_transport *t);
+int grpc_chttp2_list_pop_writing_stream(grpc_chttp2_transport *t,
+                                        grpc_chttp2_stream **s);
+
+void grpc_chttp2_list_add_written_stream(grpc_chttp2_transport *t,
+                                         grpc_chttp2_stream *s);
+int grpc_chttp2_list_pop_written_stream(grpc_chttp2_transport *t,
+                                        grpc_chttp2_stream **s);
+
+void grpc_chttp2_list_add_waiting_for_concurrency(grpc_chttp2_transport *t,
+                                                  grpc_chttp2_stream *s);
+int grpc_chttp2_list_pop_waiting_for_concurrency(grpc_chttp2_transport *t,
+                                                 grpc_chttp2_stream **s);
+
+void grpc_chttp2_list_add_stalled_by_transport(grpc_chttp2_transport *t,
+                                               grpc_chttp2_stream *s);
+int grpc_chttp2_list_pop_stalled_by_transport(grpc_chttp2_transport *t,
+                                              grpc_chttp2_stream **s);
+void grpc_chttp2_list_remove_stalled_by_transport(grpc_chttp2_transport *t,
+                                                  grpc_chttp2_stream *s);
+
+grpc_chttp2_stream *grpc_chttp2_parsing_lookup_stream(grpc_chttp2_transport *t,
+                                                      uint32_t id);
+grpc_chttp2_stream *grpc_chttp2_parsing_accept_stream(grpc_exec_ctx *exec_ctx,
+                                                      grpc_chttp2_transport *t,
+                                                      uint32_t id);
+
+void grpc_chttp2_add_incoming_goaway(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_transport *t,
+                                     uint32_t goaway_error,
+                                     gpr_slice goaway_text);
+
+void grpc_chttp2_parsing_become_skip_parser(grpc_exec_ctx *exec_ctx,
+                                            grpc_chttp2_transport *t);
+
+void grpc_chttp2_complete_closure_step(grpc_exec_ctx *exec_ctx,
+                                       grpc_chttp2_transport *t,
+                                       grpc_chttp2_stream *s,
+                                       grpc_closure **pclosure,
+                                       grpc_error *error, const char *desc);
 
 #define GRPC_CHTTP2_CLIENT_CONNECT_STRING "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
 #define GRPC_CHTTP2_CLIENT_CONNECT_STRLEN \
@@ -801,57 +586,83 @@ void grpc_chttp2_flowctl_trace(const char *file, int line, const char *phase,
                                const char *var2, int is_client,
                                uint32_t stream_id, int64_t val1, int64_t val2);
 
-void grpc_chttp2_fake_status(grpc_exec_ctx *exec_ctx,
-                             grpc_chttp2_transport_global *transport_global,
-                             grpc_chttp2_stream_global *stream,
+void grpc_chttp2_fake_status(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+                             grpc_chttp2_stream *stream,
                              grpc_status_code status, gpr_slice *details);
-void grpc_chttp2_mark_stream_closed(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global, int close_reads, int close_writes,
-    grpc_error *error);
+void grpc_chttp2_mark_stream_closed(grpc_exec_ctx *exec_ctx,
+                                    grpc_chttp2_transport *t,
+                                    grpc_chttp2_stream *s, int close_reads,
+                                    int close_writes, grpc_error *error);
 void grpc_chttp2_start_writing(grpc_exec_ctx *exec_ctx,
-                               grpc_chttp2_transport_global *transport_global);
+                               grpc_chttp2_transport *t);
 
 #ifdef GRPC_STREAM_REFCOUNT_DEBUG
-#define GRPC_CHTTP2_STREAM_REF(stream_global, reason) \
-  grpc_chttp2_stream_ref(stream_global, reason)
-#define GRPC_CHTTP2_STREAM_UNREF(exec_ctx, stream_global, reason) \
-  grpc_chttp2_stream_unref(exec_ctx, stream_global, reason)
-void grpc_chttp2_stream_ref(grpc_chttp2_stream_global *stream_global,
-                            const char *reason);
-void grpc_chttp2_stream_unref(grpc_exec_ctx *exec_ctx,
-                              grpc_chttp2_stream_global *stream_global,
+#define GRPC_CHTTP2_STREAM_REF(stream, reason) \
+  grpc_chttp2_stream_ref(stream, reason)
+#define GRPC_CHTTP2_STREAM_UNREF(exec_ctx, stream, reason) \
+  grpc_chttp2_stream_unref(exec_ctx, stream, reason)
+void grpc_chttp2_stream_ref(grpc_chttp2_stream *s, const char *reason);
+void grpc_chttp2_stream_unref(grpc_exec_ctx *exec_ctx, grpc_chttp2_stream *s,
                               const char *reason);
 #else
-#define GRPC_CHTTP2_STREAM_REF(stream_global, reason) \
-  grpc_chttp2_stream_ref(stream_global)
-#define GRPC_CHTTP2_STREAM_UNREF(exec_ctx, stream_global, reason) \
-  grpc_chttp2_stream_unref(exec_ctx, stream_global)
-void grpc_chttp2_stream_ref(grpc_chttp2_stream_global *stream_global);
-void grpc_chttp2_stream_unref(grpc_exec_ctx *exec_ctx,
-                              grpc_chttp2_stream_global *stream_global);
+#define GRPC_CHTTP2_STREAM_REF(stream, reason) grpc_chttp2_stream_ref(stream)
+#define GRPC_CHTTP2_STREAM_UNREF(exec_ctx, stream, reason) \
+  grpc_chttp2_stream_unref(exec_ctx, stream)
+void grpc_chttp2_stream_ref(grpc_chttp2_stream *s);
+void grpc_chttp2_stream_unref(grpc_exec_ctx *exec_ctx, grpc_chttp2_stream *s);
+#endif
+
+//#define GRPC_CHTTP2_REFCOUNTING_DEBUG 1
+#ifdef GRPC_CHTTP2_REFCOUNTING_DEBUG
+#define GRPC_CHTTP2_REF_TRANSPORT(t, r) \
+  grpc_chttp2_ref_transport(t, r, __FILE__, __LINE__)
+#define GRPC_CHTTP2_UNREF_TRANSPORT(cl, t, r) \
+  grpc_chttp2_unref_transport(cl, t, r, __FILE__, __LINE__)
+void grpc_chttp2_unref_transport(grpc_exec_ctx *exec_ctx,
+                                 grpc_chttp2_transport *t, const char *reason,
+                                 const char *file, int line);
+void grpc_chttp2_ref_transport(grpc_chttp2_transport *t, const char *reason,
+                               const char *file, int line);
+#else
+#define GRPC_CHTTP2_REF_TRANSPORT(t, r) grpc_chttp2_ref_transport(t)
+#define GRPC_CHTTP2_UNREF_TRANSPORT(cl, t, r) grpc_chttp2_unref_transport(cl, t)
+void grpc_chttp2_unref_transport(grpc_exec_ctx *exec_ctx,
+                                 grpc_chttp2_transport *t);
+void grpc_chttp2_ref_transport(grpc_chttp2_transport *t);
 #endif
 
 grpc_chttp2_incoming_byte_stream *grpc_chttp2_incoming_byte_stream_create(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing, uint32_t frame_size,
-    uint32_t flags, grpc_chttp2_incoming_frame_queue *add_to_queue);
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t, grpc_chttp2_stream *s,
+    uint32_t frame_size, uint32_t flags);
 void grpc_chttp2_incoming_byte_stream_push(grpc_exec_ctx *exec_ctx,
                                            grpc_chttp2_incoming_byte_stream *bs,
                                            gpr_slice slice);
 void grpc_chttp2_incoming_byte_stream_finished(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_incoming_byte_stream *bs,
-    grpc_error *error, int from_parsing_thread);
+    grpc_error *error);
 
-void grpc_chttp2_ack_ping(grpc_exec_ctx *exec_ctx,
-                          grpc_chttp2_transport_parsing *parsing,
+void grpc_chttp2_ack_ping(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                           const uint8_t *opaque_8bytes);
 
 /** add a ref to the stream and add it to the writable list;
     ref will be dropped in writing.c */
 void grpc_chttp2_become_writable(grpc_exec_ctx *exec_ctx,
-                                 grpc_chttp2_transport_global *transport_global,
-                                 grpc_chttp2_stream_global *stream_global,
-                                 bool covered_by_poller, const char *reason);
+                                 grpc_chttp2_transport *t,
+                                 grpc_chttp2_stream *s, bool covered_by_poller,
+                                 const char *reason);
+
+void grpc_chttp2_cancel_stream(grpc_exec_ctx *exec_ctx,
+                               grpc_chttp2_transport *t, grpc_chttp2_stream *s,
+                               grpc_error *due_to_error);
+
+void grpc_chttp2_maybe_complete_recv_initial_metadata(grpc_exec_ctx *exec_ctx,
+                                                      grpc_chttp2_transport *t,
+                                                      grpc_chttp2_stream *s);
+void grpc_chttp2_maybe_complete_recv_message(grpc_exec_ctx *exec_ctx,
+                                             grpc_chttp2_transport *t,
+                                             grpc_chttp2_stream *s);
+void grpc_chttp2_maybe_complete_recv_trailing_metadata(grpc_exec_ctx *exec_ctx,
+                                                       grpc_chttp2_transport *t,
+                                                       grpc_chttp2_stream *s);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_INTERNAL_H */

src/core/ext/transport/chttp2/transport/parsing.c

@@ -45,223 +45,34 @@
 #include "src/core/lib/transport/static_metadata.h"
 #include "src/core/lib/transport/timeout_encoding.h"
 
-#define TRANSPORT_FROM_PARSING(tp)                                        \
-  ((grpc_chttp2_transport *)((char *)(tp)-offsetof(grpc_chttp2_transport, \
-                                                   parsing)))
-
-static grpc_error *init_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-static grpc_error *init_header_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    int is_continuation);
-static grpc_error *init_data_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-static grpc_error *init_rst_stream_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-static grpc_error *init_settings_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-static grpc_error *init_window_update_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-static grpc_error *init_ping_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-static grpc_error *init_goaway_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing);
-static grpc_error *init_skip_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    int is_header);
-
-static grpc_error *parse_frame_slice(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    gpr_slice slice, int is_last);
-
-void grpc_chttp2_prepare_to_read(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_parsing *transport_parsing) {
-  grpc_chttp2_stream_global *stream_global;
-  grpc_chttp2_stream_parsing *stream_parsing;
-
-  GPR_TIMER_BEGIN("grpc_chttp2_prepare_to_read", 0);
-
-  transport_parsing->next_stream_id = transport_global->next_stream_id;
-  memcpy(transport_parsing->last_sent_settings,
-         transport_global->settings[GRPC_SENT_SETTINGS],
-         sizeof(transport_parsing->last_sent_settings));
-  transport_parsing->max_frame_size =
-      transport_global->settings[GRPC_ACKED_SETTINGS]
-                                [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE];
-
-  /* update the parsing view of incoming window */
-  while (grpc_chttp2_list_pop_unannounced_incoming_window_available(
-      transport_global, transport_parsing, &stream_global, &stream_parsing)) {
-    GRPC_CHTTP2_FLOW_MOVE_STREAM("parse", transport_parsing, stream_parsing,
-                                 incoming_window, stream_global,
-                                 unannounced_incoming_window_for_parse);
-  }
-
-  GPR_TIMER_END("grpc_chttp2_prepare_to_read", 0);
-}
-
-void grpc_chttp2_publish_reads(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_parsing *transport_parsing) {
-  grpc_chttp2_stream_global *stream_global;
-  grpc_chttp2_stream_parsing *stream_parsing;
-  int was_zero;
-  int is_zero;
-
-  /* transport_parsing->last_incoming_stream_id is used as
-     last-grpc_chttp2_stream-id when
-     sending GOAWAY frame.
-     https://tools.ietf.org/html/draft-ietf-httpbis-http2-17#section-6.8
-     says that last-grpc_chttp2_stream-id is peer-initiated grpc_chttp2_stream
-     ID.  So,
-     since we don't have server pushed streams, client should send
-     GOAWAY last-grpc_chttp2_stream-id=0 in this case. */
-  if (!transport_parsing->is_client) {
-    transport_global->last_incoming_stream_id =
-        transport_parsing->last_incoming_stream_id;
-  }
-
-  /* update global settings */
-  if (transport_parsing->settings_updated) {
-    memcpy(transport_global->settings[GRPC_PEER_SETTINGS],
-           transport_parsing->settings, sizeof(transport_parsing->settings));
-    transport_parsing->settings_updated = 0;
-  }
-
-  /* update settings based on ack if received */
-  if (transport_parsing->settings_ack_received) {
-    memcpy(transport_global->settings[GRPC_ACKED_SETTINGS],
-           transport_global->settings[GRPC_SENT_SETTINGS],
-           GRPC_CHTTP2_NUM_SETTINGS * sizeof(uint32_t));
-    transport_parsing->settings_ack_received = 0;
-    transport_global->sent_local_settings = 0;
-  }
-
-  /* move goaway to the global state if we received one (it will be
-     published later */
-  if (transport_parsing->goaway_received) {
-    grpc_chttp2_add_incoming_goaway(exec_ctx, transport_global,
-                                    (uint32_t)transport_parsing->goaway_error,
-                                    transport_parsing->goaway_text);
-    transport_parsing->goaway_text = gpr_empty_slice();
-    transport_parsing->goaway_received = 0;
-  }
-
-  /* propagate flow control tokens to global state */
-  was_zero = transport_global->outgoing_window <= 0;
-  GRPC_CHTTP2_FLOW_MOVE_TRANSPORT("parsed", transport_global, outgoing_window,
-                                  transport_parsing, outgoing_window);
-  is_zero = transport_global->outgoing_window <= 0;
-  if (was_zero && !is_zero) {
-    grpc_chttp2_initiate_write(exec_ctx, transport_global, false,
-                               "new_global_flow_control");
-  }
-
-  if (transport_parsing->incoming_window <
-      transport_global->connection_window_target * 3 / 4) {
-    int64_t announce_bytes = transport_global->connection_window_target -
-                             transport_parsing->incoming_window;
-    GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parsed", transport_global,
-                                      announce_incoming_window, announce_bytes);
-    GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parsed", transport_parsing,
-                                      incoming_window, announce_bytes);
-    grpc_chttp2_initiate_write(exec_ctx, transport_global, false,
-                               "global incoming window");
-  }
-
-  /* for each stream that saw an update, fixup global state */
-  while (grpc_chttp2_list_pop_parsing_seen_stream(
-      transport_global, transport_parsing, &stream_global, &stream_parsing)) {
-    if (stream_parsing->seen_error) {
-      stream_global->seen_error = true;
-      stream_global->exceeded_metadata_size =
-          stream_parsing->exceeded_metadata_size;
-      grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
-    }
-
-    /* flush stats to global stream state */
-    grpc_transport_move_stats(&stream_parsing->stats, &stream_global->stats);
-
-    /* update outgoing flow control window */
-    was_zero = stream_global->outgoing_window <= 0;
-    GRPC_CHTTP2_FLOW_MOVE_STREAM("parsed", transport_global, stream_global,
-                                 outgoing_window, stream_parsing,
-                                 outgoing_window);
-    is_zero = stream_global->outgoing_window <= 0;
-    if (was_zero && !is_zero) {
-      grpc_chttp2_become_writable(exec_ctx, transport_global, stream_global,
-                                  false, "stream.read_flow_control");
-    }
-
-    stream_global->max_recv_bytes -= (uint32_t)GPR_MIN(
-        stream_global->max_recv_bytes, stream_parsing->received_bytes);
-    stream_parsing->received_bytes = 0;
-
-    /* publish incoming stream ops */
-    if (stream_global->incoming_frames.tail != NULL) {
-      stream_global->incoming_frames.tail->is_tail = 0;
-    }
-    if (stream_parsing->data_parser.incoming_frames.head != NULL) {
-      grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
-    }
-    grpc_chttp2_incoming_frame_queue_merge(
-        &stream_global->incoming_frames,
-        &stream_parsing->data_parser.incoming_frames);
-    if (stream_global->incoming_frames.tail != NULL) {
-      stream_global->incoming_frames.tail->is_tail = 1;
-    }
-
-    if (!stream_global->published_initial_metadata &&
-        stream_parsing->got_metadata_on_parse[0]) {
-      stream_parsing->got_metadata_on_parse[0] = 0;
-      stream_global->published_initial_metadata = 1;
-      GPR_SWAP(grpc_chttp2_incoming_metadata_buffer,
-               stream_parsing->metadata_buffer[0],
-               stream_global->received_initial_metadata);
-      grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
-    }
-    if (!stream_global->published_trailing_metadata &&
-        stream_parsing->got_metadata_on_parse[1]) {
-      stream_parsing->got_metadata_on_parse[1] = 0;
-      stream_global->published_trailing_metadata = 1;
-      GPR_SWAP(grpc_chttp2_incoming_metadata_buffer,
-               stream_parsing->metadata_buffer[1],
-               stream_global->received_trailing_metadata);
-      grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
-    }
-
-    if (stream_parsing->forced_close_error != GRPC_ERROR_NONE) {
-      intptr_t reason;
-      bool has_reason = grpc_error_get_int(stream_parsing->forced_close_error,
-                                           GRPC_ERROR_INT_HTTP2_ERROR, &reason);
-      if (has_reason && reason != GRPC_CHTTP2_NO_ERROR) {
-        grpc_status_code status_code =
-            has_reason
-                ? grpc_chttp2_http2_error_to_grpc_status(
-                      (grpc_chttp2_error_code)reason, stream_global->deadline)
-                : GRPC_STATUS_INTERNAL;
-        const char *status_details =
-            grpc_error_string(stream_parsing->forced_close_error);
-        gpr_slice slice_details = gpr_slice_from_copied_string(status_details);
-        grpc_error_free_string(status_details);
-        grpc_chttp2_fake_status(exec_ctx, transport_global, stream_global,
-                                status_code, &slice_details);
-      }
-      grpc_chttp2_mark_stream_closed(exec_ctx, transport_global, stream_global,
-                                     1, 1, stream_parsing->forced_close_error);
-    }
-
-    if (stream_parsing->received_close) {
-      grpc_chttp2_mark_stream_closed(exec_ctx, transport_global, stream_global,
-                                     1, 0, GRPC_ERROR_NONE);
-    }
-  }
-}
-
-grpc_error *grpc_chttp2_perform_read(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    gpr_slice slice) {
+static grpc_error *init_frame_parser(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_transport *t);
+static grpc_error *init_header_frame_parser(grpc_exec_ctx *exec_ctx,
+                                            grpc_chttp2_transport *t,
+                                            int is_continuation);
+static grpc_error *init_data_frame_parser(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t);
+static grpc_error *init_rst_stream_parser(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t);
+static grpc_error *init_settings_frame_parser(grpc_exec_ctx *exec_ctx,
+                                              grpc_chttp2_transport *t);
+static grpc_error *init_window_update_frame_parser(grpc_exec_ctx *exec_ctx,
+                                                   grpc_chttp2_transport *t);
+static grpc_error *init_ping_parser(grpc_exec_ctx *exec_ctx,
+                                    grpc_chttp2_transport *t);
+static grpc_error *init_goaway_parser(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_transport *t);
+static grpc_error *init_skip_frame_parser(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t,
+                                          int is_header);
+
+static grpc_error *parse_frame_slice(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_transport *t, gpr_slice slice,
+                                     int is_last);
+
+grpc_error *grpc_chttp2_perform_read(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_transport *t,
+                                     gpr_slice slice) {
   uint8_t *beg = GPR_SLICE_START_PTR(slice);
   uint8_t *end = GPR_SLICE_END_PTR(slice);
   uint8_t *cur = beg;
@@ -269,7 +80,7 @@ grpc_error *grpc_chttp2_perform_read(
 
   if (cur == end) return GRPC_ERROR_NONE;
 
-  switch (transport_parsing->deframe_state) {
+  switch (t->deframe_state) {
     case GRPC_DTS_CLIENT_PREFIX_0:
     case GRPC_DTS_CLIENT_PREFIX_1:
     case GRPC_DTS_CLIENT_PREFIX_2:
@@ -294,25 +105,22 @@ grpc_error *grpc_chttp2_perform_read(
     case GRPC_DTS_CLIENT_PREFIX_21:
     case GRPC_DTS_CLIENT_PREFIX_22:
     case GRPC_DTS_CLIENT_PREFIX_23:
-      while (cur != end && transport_parsing->deframe_state != GRPC_DTS_FH_0) {
-        if (*cur != GRPC_CHTTP2_CLIENT_CONNECT_STRING[transport_parsing
-                                                          ->deframe_state]) {
+      while (cur != end && t->deframe_state != GRPC_DTS_FH_0) {
+        if (*cur != GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state]) {
           char *msg;
           gpr_asprintf(
               &msg,
               "Connect string mismatch: expected '%c' (%d) got '%c' (%d) "
               "at byte %d",
-              GRPC_CHTTP2_CLIENT_CONNECT_STRING[transport_parsing
-                                                    ->deframe_state],
-              (int)(uint8_t)GRPC_CHTTP2_CLIENT_CONNECT_STRING
-                  [transport_parsing->deframe_state],
-              *cur, (int)*cur, transport_parsing->deframe_state);
+              GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state],
+              (int)(uint8_t)GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state],
+              *cur, (int)*cur, t->deframe_state);
           err = GRPC_ERROR_CREATE(msg);
           gpr_free(msg);
           return err;
         }
         ++cur;
-        ++transport_parsing->deframe_state;
+        ++t->deframe_state;
       }
       if (cur == end) {
         return GRPC_ERROR_NONE;
@@ -321,100 +129,95 @@ grpc_error *grpc_chttp2_perform_read(
     dts_fh_0:
     case GRPC_DTS_FH_0:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_frame_size = ((uint32_t)*cur) << 16;
+      t->incoming_frame_size = ((uint32_t)*cur) << 16;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_1;
+        t->deframe_state = GRPC_DTS_FH_1;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_1:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_frame_size |= ((uint32_t)*cur) << 8;
+      t->incoming_frame_size |= ((uint32_t)*cur) << 8;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_2;
+        t->deframe_state = GRPC_DTS_FH_2;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_2:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_frame_size |= *cur;
+      t->incoming_frame_size |= *cur;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_3;
+        t->deframe_state = GRPC_DTS_FH_3;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_3:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_frame_type = *cur;
+      t->incoming_frame_type = *cur;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_4;
+        t->deframe_state = GRPC_DTS_FH_4;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_4:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_frame_flags = *cur;
+      t->incoming_frame_flags = *cur;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_5;
+        t->deframe_state = GRPC_DTS_FH_5;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_5:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_stream_id = (((uint32_t)*cur) & 0x7f) << 24;
+      t->incoming_stream_id = (((uint32_t)*cur) & 0x7f) << 24;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_6;
+        t->deframe_state = GRPC_DTS_FH_6;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_6:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_stream_id |= ((uint32_t)*cur) << 16;
+      t->incoming_stream_id |= ((uint32_t)*cur) << 16;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_7;
+        t->deframe_state = GRPC_DTS_FH_7;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_7:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_stream_id |= ((uint32_t)*cur) << 8;
+      t->incoming_stream_id |= ((uint32_t)*cur) << 8;
       if (++cur == end) {
-        transport_parsing->deframe_state = GRPC_DTS_FH_8;
+        t->deframe_state = GRPC_DTS_FH_8;
         return GRPC_ERROR_NONE;
       }
     /* fallthrough */
     case GRPC_DTS_FH_8:
       GPR_ASSERT(cur < end);
-      transport_parsing->incoming_stream_id |= ((uint32_t)*cur);
-      transport_parsing->deframe_state = GRPC_DTS_FRAME;
-      err = init_frame_parser(exec_ctx, transport_parsing);
+      t->incoming_stream_id |= ((uint32_t)*cur);
+      t->deframe_state = GRPC_DTS_FRAME;
+      err = init_frame_parser(exec_ctx, t);
       if (err != GRPC_ERROR_NONE) {
         return err;
       }
-      if (transport_parsing->incoming_stream_id != 0 &&
-          transport_parsing->incoming_stream_id >
-              transport_parsing->last_incoming_stream_id) {
-        transport_parsing->last_incoming_stream_id =
-            transport_parsing->incoming_stream_id;
-      }
-      if (transport_parsing->incoming_frame_size == 0) {
-        err = parse_frame_slice(exec_ctx, transport_parsing, gpr_empty_slice(),
-                                1);
+      if (t->incoming_frame_size == 0) {
+        err = parse_frame_slice(exec_ctx, t, gpr_empty_slice(), 1);
         if (err != GRPC_ERROR_NONE) {
           return err;
         }
-        transport_parsing->incoming_stream = NULL;
+        t->incoming_stream = NULL;
         if (++cur == end) {
-          transport_parsing->deframe_state = GRPC_DTS_FH_0;
+          t->deframe_state = GRPC_DTS_FH_0;
           return GRPC_ERROR_NONE;
         }
         goto dts_fh_0; /* loop */
-      } else if (transport_parsing->incoming_frame_size >
-                 transport_parsing->max_frame_size) {
+      } else if (t->incoming_frame_size >
+                 t->settings[GRPC_ACKED_SETTINGS]
+                            [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE]) {
         char *msg;
         gpr_asprintf(&msg, "Frame size %d is larger than max frame size %d",
-                     transport_parsing->incoming_frame_size,
-                     transport_parsing->max_frame_size);
+                     t->incoming_frame_size,
+                     t->settings[GRPC_ACKED_SETTINGS]
+                                [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE]);
         err = GRPC_ERROR_CREATE(msg);
         gpr_free(msg);
         return err;
@@ -425,41 +228,39 @@ grpc_error *grpc_chttp2_perform_read(
     /* fallthrough */
     case GRPC_DTS_FRAME:
       GPR_ASSERT(cur < end);
-      if ((uint32_t)(end - cur) == transport_parsing->incoming_frame_size) {
-        err = parse_frame_slice(exec_ctx, transport_parsing,
+      if ((uint32_t)(end - cur) == t->incoming_frame_size) {
+        err = parse_frame_slice(exec_ctx, t,
                                 gpr_slice_sub_no_ref(slice, (size_t)(cur - beg),
                                                      (size_t)(end - beg)),
                                 1);
         if (err != GRPC_ERROR_NONE) {
           return err;
         }
-        transport_parsing->deframe_state = GRPC_DTS_FH_0;
-        transport_parsing->incoming_stream = NULL;
+        t->deframe_state = GRPC_DTS_FH_0;
+        t->incoming_stream = NULL;
         return GRPC_ERROR_NONE;
-      } else if ((uint32_t)(end - cur) >
-                 transport_parsing->incoming_frame_size) {
+      } else if ((uint32_t)(end - cur) > t->incoming_frame_size) {
         size_t cur_offset = (size_t)(cur - beg);
         err = parse_frame_slice(
-            exec_ctx, transport_parsing,
-            gpr_slice_sub_no_ref(
-                slice, cur_offset,
-                cur_offset + transport_parsing->incoming_frame_size),
+            exec_ctx, t,
+            gpr_slice_sub_no_ref(slice, cur_offset,
+                                 cur_offset + t->incoming_frame_size),
             1);
         if (err != GRPC_ERROR_NONE) {
           return err;
         }
-        cur += transport_parsing->incoming_frame_size;
-        transport_parsing->incoming_stream = NULL;
+        cur += t->incoming_frame_size;
+        t->incoming_stream = NULL;
         goto dts_fh_0; /* loop */
       } else {
-        err = parse_frame_slice(exec_ctx, transport_parsing,
+        err = parse_frame_slice(exec_ctx, t,
                                 gpr_slice_sub_no_ref(slice, (size_t)(cur - beg),
                                                      (size_t)(end - beg)),
                                 0);
         if (err != GRPC_ERROR_NONE) {
           return err;
         }
-        transport_parsing->incoming_frame_size -= (uint32_t)(end - cur);
+        t->incoming_frame_size -= (uint32_t)(end - cur);
         return GRPC_ERROR_NONE;
       }
       GPR_UNREACHABLE_CODE(return 0);
@@ -468,175 +269,164 @@ grpc_error *grpc_chttp2_perform_read(
   GPR_UNREACHABLE_CODE(return 0);
 }
 
-static grpc_error *init_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
-  if (transport_parsing->is_first_frame &&
-      transport_parsing->incoming_frame_type != GRPC_CHTTP2_FRAME_SETTINGS) {
+static grpc_error *init_frame_parser(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_transport *t) {
+  if (t->is_first_frame &&
+      t->incoming_frame_type != GRPC_CHTTP2_FRAME_SETTINGS) {
     char *msg;
     gpr_asprintf(
         &msg, "Expected SETTINGS frame as the first frame, got frame type %d",
-        transport_parsing->incoming_frame_type);
+        t->incoming_frame_type);
     grpc_error *err = GRPC_ERROR_CREATE(msg);
     gpr_free(msg);
     return err;
   }
-  transport_parsing->is_first_frame = false;
-  if (transport_parsing->expect_continuation_stream_id != 0) {
-    if (transport_parsing->incoming_frame_type !=
-        GRPC_CHTTP2_FRAME_CONTINUATION) {
+  t->is_first_frame = false;
+  if (t->expect_continuation_stream_id != 0) {
+    if (t->incoming_frame_type != GRPC_CHTTP2_FRAME_CONTINUATION) {
       char *msg;
       gpr_asprintf(&msg, "Expected CONTINUATION frame, got frame type %02x",
-                   transport_parsing->incoming_frame_type);
+                   t->incoming_frame_type);
       grpc_error *err = GRPC_ERROR_CREATE(msg);
       gpr_free(msg);
       return err;
     }
-    if (transport_parsing->expect_continuation_stream_id !=
-        transport_parsing->incoming_stream_id) {
+    if (t->expect_continuation_stream_id != t->incoming_stream_id) {
       char *msg;
       gpr_asprintf(
           &msg,
           "Expected CONTINUATION frame for grpc_chttp2_stream %08x, got "
           "grpc_chttp2_stream %08x",
-          transport_parsing->expect_continuation_stream_id,
-          transport_parsing->incoming_stream_id);
+          t->expect_continuation_stream_id, t->incoming_stream_id);
       grpc_error *err = GRPC_ERROR_CREATE(msg);
       gpr_free(msg);
       return err;
     }
-    return init_header_frame_parser(exec_ctx, transport_parsing, 1);
+    return init_header_frame_parser(exec_ctx, t, 1);
   }
-  switch (transport_parsing->incoming_frame_type) {
+  switch (t->incoming_frame_type) {
     case GRPC_CHTTP2_FRAME_DATA:
-      return init_data_frame_parser(exec_ctx, transport_parsing);
+      return init_data_frame_parser(exec_ctx, t);
     case GRPC_CHTTP2_FRAME_HEADER:
-      return init_header_frame_parser(exec_ctx, transport_parsing, 0);
+      return init_header_frame_parser(exec_ctx, t, 0);
     case GRPC_CHTTP2_FRAME_CONTINUATION:
       return GRPC_ERROR_CREATE("Unexpected CONTINUATION frame");
     case GRPC_CHTTP2_FRAME_RST_STREAM:
-      return init_rst_stream_parser(exec_ctx, transport_parsing);
+      return init_rst_stream_parser(exec_ctx, t);
     case GRPC_CHTTP2_FRAME_SETTINGS:
-      return init_settings_frame_parser(exec_ctx, transport_parsing);
+      return init_settings_frame_parser(exec_ctx, t);
     case GRPC_CHTTP2_FRAME_WINDOW_UPDATE:
-      return init_window_update_frame_parser(exec_ctx, transport_parsing);
+      return init_window_update_frame_parser(exec_ctx, t);
     case GRPC_CHTTP2_FRAME_PING:
-      return init_ping_parser(exec_ctx, transport_parsing);
+      return init_ping_parser(exec_ctx, t);
     case GRPC_CHTTP2_FRAME_GOAWAY:
-      return init_goaway_parser(exec_ctx, transport_parsing);
+      return init_goaway_parser(exec_ctx, t);
     default:
       if (grpc_http_trace) {
-        gpr_log(GPR_ERROR, "Unknown frame type %02x",
-                transport_parsing->incoming_frame_type);
+        gpr_log(GPR_ERROR, "Unknown frame type %02x", t->incoming_frame_type);
       }
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 0);
+      return init_skip_frame_parser(exec_ctx, t, 0);
   }
 }
 
 static grpc_error *skip_parser(grpc_exec_ctx *exec_ctx, void *parser,
-                               grpc_chttp2_transport_parsing *transport_parsing,
-                               grpc_chttp2_stream_parsing *stream_parsing,
+                               grpc_chttp2_transport *t, grpc_chttp2_stream *s,
                                gpr_slice slice, int is_last) {
   return GRPC_ERROR_NONE;
 }
 
-static void skip_header(void *tp, grpc_mdelem *md) { GRPC_MDELEM_UNREF(md); }
+static void skip_header(grpc_exec_ctx *exec_ctx, void *tp, grpc_mdelem *md) {
+  GRPC_MDELEM_UNREF(md);
+}
 
-static grpc_error *init_skip_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    int is_header) {
+static grpc_error *init_skip_frame_parser(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t,
+                                          int is_header) {
   if (is_header) {
-    uint8_t is_eoh = transport_parsing->expect_continuation_stream_id != 0;
-    transport_parsing->parser = grpc_chttp2_header_parser_parse;
-    transport_parsing->parser_data = &transport_parsing->hpack_parser;
-    transport_parsing->hpack_parser.on_header = skip_header;
-    transport_parsing->hpack_parser.on_header_user_data = NULL;
-    transport_parsing->hpack_parser.is_boundary = is_eoh;
-    transport_parsing->hpack_parser.is_eof =
-        (uint8_t)(is_eoh ? transport_parsing->header_eof : 0);
+    uint8_t is_eoh = t->expect_continuation_stream_id != 0;
+    t->parser = grpc_chttp2_header_parser_parse;
+    t->parser_data = &t->hpack_parser;
+    t->hpack_parser.on_header = skip_header;
+    t->hpack_parser.on_header_user_data = NULL;
+    t->hpack_parser.is_boundary = is_eoh;
+    t->hpack_parser.is_eof = (uint8_t)(is_eoh ? t->header_eof : 0);
   } else {
-    transport_parsing->parser = skip_parser;
+    t->parser = skip_parser;
   }
   return GRPC_ERROR_NONE;
 }
 
-void grpc_chttp2_parsing_become_skip_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
-  init_skip_frame_parser(
-      exec_ctx, transport_parsing,
-      transport_parsing->parser == grpc_chttp2_header_parser_parse);
+void grpc_chttp2_parsing_become_skip_parser(grpc_exec_ctx *exec_ctx,
+                                            grpc_chttp2_transport *t) {
+  init_skip_frame_parser(exec_ctx, t,
+                         t->parser == grpc_chttp2_header_parser_parse);
 }
 
-static grpc_error *update_incoming_window(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing) {
-  uint32_t incoming_frame_size = transport_parsing->incoming_frame_size;
-  if (incoming_frame_size > transport_parsing->incoming_window) {
+static grpc_error *update_incoming_window(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s) {
+  uint32_t incoming_frame_size = t->incoming_frame_size;
+  if (incoming_frame_size > t->incoming_window) {
     char *msg;
     gpr_asprintf(&msg, "frame of size %d overflows incoming window of %" PRId64,
-                 transport_parsing->incoming_frame_size,
-                 transport_parsing->incoming_window);
+                 t->incoming_frame_size, t->incoming_window);
     grpc_error *err = GRPC_ERROR_CREATE(msg);
     gpr_free(msg);
     return err;
   }
 
-  if (incoming_frame_size > stream_parsing->incoming_window) {
+  if (incoming_frame_size > s->incoming_window) {
     char *msg;
     gpr_asprintf(&msg, "frame of size %d overflows incoming window of %" PRId64,
-                 transport_parsing->incoming_frame_size,
-                 stream_parsing->incoming_window);
+                 t->incoming_frame_size, s->incoming_window);
     grpc_error *err = GRPC_ERROR_CREATE(msg);
     gpr_free(msg);
     return err;
   }
 
-  GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("parse", transport_parsing, incoming_window,
+  GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("parse", t, incoming_window,
                                    incoming_frame_size);
-  GRPC_CHTTP2_FLOW_DEBIT_STREAM("parse", transport_parsing, stream_parsing,
-                                incoming_window, incoming_frame_size);
-  stream_parsing->received_bytes += incoming_frame_size;
-
-  grpc_chttp2_list_add_parsing_seen_stream(transport_parsing, stream_parsing);
+  GRPC_CHTTP2_FLOW_DEBIT_STREAM("parse", t, s, incoming_window,
+                                incoming_frame_size);
+  s->received_bytes += incoming_frame_size;
+  s->max_recv_bytes -=
+      (uint32_t)GPR_MIN(s->max_recv_bytes, incoming_frame_size);
 
   return GRPC_ERROR_NONE;
 }
 
-static grpc_error *init_data_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
-  grpc_chttp2_stream_parsing *stream_parsing =
-      grpc_chttp2_parsing_lookup_stream(transport_parsing,
-                                        transport_parsing->incoming_stream_id);
+static grpc_error *init_data_frame_parser(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t) {
+  grpc_chttp2_stream *s =
+      grpc_chttp2_parsing_lookup_stream(t, t->incoming_stream_id);
   grpc_error *err = GRPC_ERROR_NONE;
-  if (stream_parsing == NULL) {
-    return init_skip_frame_parser(exec_ctx, transport_parsing, 0);
+  if (s == NULL) {
+    return init_skip_frame_parser(exec_ctx, t, 0);
   }
-  stream_parsing->stats.incoming.framing_bytes += 9;
-  if (stream_parsing->received_close) {
-    return init_skip_frame_parser(exec_ctx, transport_parsing, 0);
+  s->stats.incoming.framing_bytes += 9;
+  if (s->read_closed) {
+    return init_skip_frame_parser(exec_ctx, t, 0);
   }
   if (err == GRPC_ERROR_NONE) {
-    err = update_incoming_window(exec_ctx, transport_parsing, stream_parsing);
+    err = update_incoming_window(exec_ctx, t, s);
   }
   if (err == GRPC_ERROR_NONE) {
-    err = grpc_chttp2_data_parser_begin_frame(
-        &stream_parsing->data_parser, transport_parsing->incoming_frame_flags,
-        stream_parsing->id);
+    err = grpc_chttp2_data_parser_begin_frame(&s->data_parser,
+                                              t->incoming_frame_flags, s->id);
   }
   if (err == GRPC_ERROR_NONE) {
-    transport_parsing->incoming_stream = stream_parsing;
-    transport_parsing->parser = grpc_chttp2_data_parser_parse;
-    transport_parsing->parser_data = &stream_parsing->data_parser;
+    t->incoming_stream = s;
+    t->parser = grpc_chttp2_data_parser_parse;
+    t->parser_data = &s->data_parser;
     return GRPC_ERROR_NONE;
   } else if (grpc_error_get_int(err, GRPC_ERROR_INT_STREAM_ID, NULL)) {
     /* handle stream errors by closing the stream */
-    stream_parsing->received_close = 1;
-    stream_parsing->forced_close_error = err;
+    grpc_chttp2_mark_stream_closed(exec_ctx, t, s, true, false, err);
     gpr_slice_buffer_add(
-        &transport_parsing->qbuf,
-        grpc_chttp2_rst_stream_create(transport_parsing->incoming_stream_id,
-                                      GRPC_CHTTP2_PROTOCOL_ERROR,
-                                      &stream_parsing->stats.outgoing));
-    return init_skip_frame_parser(exec_ctx, transport_parsing, 0);
+        &t->qbuf, grpc_chttp2_rst_stream_create(t->incoming_stream_id,
+                                                GRPC_CHTTP2_PROTOCOL_ERROR,
+                                                &s->stats.outgoing));
+    return init_skip_frame_parser(exec_ctx, t, 0);
   } else {
     return err;
   }
@@ -644,23 +434,22 @@ static grpc_error *init_data_frame_parser(
 
 static void free_timeout(void *p) { gpr_free(p); }
 
-static void on_initial_header(void *tp, grpc_mdelem *md) {
-  grpc_chttp2_transport_parsing *transport_parsing = tp;
-  grpc_chttp2_stream_parsing *stream_parsing =
-      transport_parsing->incoming_stream;
+static void on_initial_header(grpc_exec_ctx *exec_ctx, void *tp,
+                              grpc_mdelem *md) {
+  grpc_chttp2_transport *t = tp;
+  grpc_chttp2_stream *s = t->incoming_stream;
 
   GPR_TIMER_BEGIN("on_initial_header", 0);
 
-  GPR_ASSERT(stream_parsing);
+  GPR_ASSERT(s != NULL);
 
   GRPC_CHTTP2_IF_TRACING(gpr_log(
-      GPR_INFO, "HTTP:%d:HDR:%s: %s: %s", stream_parsing->id,
-      transport_parsing->is_client ? "CLI" : "SVR",
+      GPR_INFO, "HTTP:%d:HDR:%s: %s: %s", s->id, t->is_client ? "CLI" : "SVR",
       grpc_mdstr_as_c_string(md->key), grpc_mdstr_as_c_string(md->value)));
 
   if (md->key == GRPC_MDSTR_GRPC_STATUS && md != GRPC_MDELEM_GRPC_STATUS_0) {
     /* TODO(ctiller): check for a status like " 0" */
-    stream_parsing->seen_error = true;
+    s->seen_error = true;
   }
 
   if (md->key == GRPC_MDSTR_GRPC_TIMEOUT) {
@@ -677,306 +466,273 @@ static void on_initial_header(void *tp, grpc_mdelem *md) {
       grpc_mdelem_set_user_data(md, free_timeout, cached_timeout);
     }
     grpc_chttp2_incoming_metadata_buffer_set_deadline(
-        &stream_parsing->metadata_buffer[0],
+        &s->metadata_buffer[0],
         gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), *cached_timeout));
     GRPC_MDELEM_UNREF(md);
   } else {
-    const size_t new_size =
-        stream_parsing->metadata_buffer[0].size + GRPC_MDELEM_LENGTH(md);
-    grpc_chttp2_transport_global *transport_global =
-        &TRANSPORT_FROM_PARSING(transport_parsing)->global;
+    const size_t new_size = s->metadata_buffer[0].size + GRPC_MDELEM_LENGTH(md);
     const size_t metadata_size_limit =
-        transport_global->settings[GRPC_LOCAL_SETTINGS]
-                                  [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
+        t->settings[GRPC_ACKED_SETTINGS]
+                   [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
     if (new_size > metadata_size_limit) {
-      if (!stream_parsing->exceeded_metadata_size) {
-        gpr_log(GPR_DEBUG,
-                "received initial metadata size exceeds limit (%" PRIuPTR
-                " vs. %" PRIuPTR ")",
-                new_size, metadata_size_limit);
-        stream_parsing->seen_error = true;
-        stream_parsing->exceeded_metadata_size = true;
-      }
+      gpr_log(GPR_DEBUG,
+              "received initial metadata size exceeds limit (%" PRIuPTR
+              " vs. %" PRIuPTR ")",
+              new_size, metadata_size_limit);
+      grpc_chttp2_cancel_stream(
+          exec_ctx, t, s,
+          grpc_error_set_int(
+              GRPC_ERROR_CREATE("received initial metadata size exceeds limit"),
+              GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED));
+      grpc_chttp2_parsing_become_skip_parser(exec_ctx, t);
+      s->seen_error = true;
       GRPC_MDELEM_UNREF(md);
     } else {
-      grpc_chttp2_incoming_metadata_buffer_add(
-          &stream_parsing->metadata_buffer[0], md);
+      grpc_chttp2_incoming_metadata_buffer_add(&s->metadata_buffer[0], md);
     }
   }
 
-  grpc_chttp2_list_add_parsing_seen_stream(transport_parsing, stream_parsing);
-
   GPR_TIMER_END("on_initial_header", 0);
 }
 
-static void on_trailing_header(void *tp, grpc_mdelem *md) {
-  grpc_chttp2_transport_parsing *transport_parsing = tp;
-  grpc_chttp2_stream_parsing *stream_parsing =
-      transport_parsing->incoming_stream;
+static void on_trailing_header(grpc_exec_ctx *exec_ctx, void *tp,
+                               grpc_mdelem *md) {
+  grpc_chttp2_transport *t = tp;
+  grpc_chttp2_stream *s = t->incoming_stream;
 
   GPR_TIMER_BEGIN("on_trailing_header", 0);
 
-  GPR_ASSERT(stream_parsing);
+  GPR_ASSERT(s != NULL);
 
   GRPC_CHTTP2_IF_TRACING(gpr_log(
-      GPR_INFO, "HTTP:%d:TRL:%s: %s: %s", stream_parsing->id,
-      transport_parsing->is_client ? "CLI" : "SVR",
+      GPR_INFO, "HTTP:%d:TRL:%s: %s: %s", s->id, t->is_client ? "CLI" : "SVR",
       grpc_mdstr_as_c_string(md->key), grpc_mdstr_as_c_string(md->value)));
 
   if (md->key == GRPC_MDSTR_GRPC_STATUS && md != GRPC_MDELEM_GRPC_STATUS_0) {
     /* TODO(ctiller): check for a status like " 0" */
-    stream_parsing->seen_error = true;
+    s->seen_error = true;
   }
 
-  const size_t new_size =
-      stream_parsing->metadata_buffer[1].size + GRPC_MDELEM_LENGTH(md);
-  grpc_chttp2_transport_global *transport_global =
-      &TRANSPORT_FROM_PARSING(transport_parsing)->global;
+  const size_t new_size = s->metadata_buffer[1].size + GRPC_MDELEM_LENGTH(md);
   const size_t metadata_size_limit =
-      transport_global->settings[GRPC_LOCAL_SETTINGS]
-                                [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
+      t->settings[GRPC_ACKED_SETTINGS]
+                 [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
   if (new_size > metadata_size_limit) {
-    if (!stream_parsing->exceeded_metadata_size) {
-      gpr_log(GPR_DEBUG,
-              "received trailing metadata size exceeds limit (%" PRIuPTR
-              " vs. %" PRIuPTR ")",
-              new_size, metadata_size_limit);
-      stream_parsing->seen_error = true;
-      stream_parsing->exceeded_metadata_size = true;
-    }
+    gpr_log(GPR_DEBUG,
+            "received trailing metadata size exceeds limit (%" PRIuPTR
+            " vs. %" PRIuPTR ")",
+            new_size, metadata_size_limit);
+    grpc_chttp2_cancel_stream(
+        exec_ctx, t, s,
+        grpc_error_set_int(
+            GRPC_ERROR_CREATE("received trailing metadata size exceeds limit"),
+            GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED));
+    grpc_chttp2_parsing_become_skip_parser(exec_ctx, t);
+    s->seen_error = true;
     GRPC_MDELEM_UNREF(md);
   } else {
-    grpc_chttp2_incoming_metadata_buffer_add(
-        &stream_parsing->metadata_buffer[1], md);
+    grpc_chttp2_incoming_metadata_buffer_add(&s->metadata_buffer[1], md);
   }
 
-  grpc_chttp2_list_add_parsing_seen_stream(transport_parsing, stream_parsing);
-
   GPR_TIMER_END("on_trailing_header", 0);
 }
 
-static grpc_error *init_header_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    int is_continuation) {
-  uint8_t is_eoh = (transport_parsing->incoming_frame_flags &
-                    GRPC_CHTTP2_DATA_FLAG_END_HEADERS) != 0;
-  int via_accept = 0;
-  grpc_chttp2_stream_parsing *stream_parsing;
+static grpc_error *init_header_frame_parser(grpc_exec_ctx *exec_ctx,
+                                            grpc_chttp2_transport *t,
+                                            int is_continuation) {
+  uint8_t is_eoh =
+      (t->incoming_frame_flags & GRPC_CHTTP2_DATA_FLAG_END_HEADERS) != 0;
+  grpc_chttp2_stream *s;
 
   /* TODO(ctiller): when to increment header_frames_received? */
 
   if (is_eoh) {
-    transport_parsing->expect_continuation_stream_id = 0;
+    t->expect_continuation_stream_id = 0;
   } else {
-    transport_parsing->expect_continuation_stream_id =
-        transport_parsing->incoming_stream_id;
+    t->expect_continuation_stream_id = t->incoming_stream_id;
   }
 
   if (!is_continuation) {
-    transport_parsing->header_eof = (transport_parsing->incoming_frame_flags &
-                                     GRPC_CHTTP2_DATA_FLAG_END_STREAM) != 0;
+    t->header_eof =
+        (t->incoming_frame_flags & GRPC_CHTTP2_DATA_FLAG_END_STREAM) != 0;
   }
 
   /* could be a new grpc_chttp2_stream or an existing grpc_chttp2_stream */
-  stream_parsing = grpc_chttp2_parsing_lookup_stream(
-      transport_parsing, transport_parsing->incoming_stream_id);
-  if (stream_parsing == NULL) {
+  s = grpc_chttp2_parsing_lookup_stream(t, t->incoming_stream_id);
+  if (s == NULL) {
     if (is_continuation) {
-      gpr_log(GPR_ERROR,
-              "grpc_chttp2_stream disbanded before CONTINUATION received");
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 1);
+      GRPC_CHTTP2_IF_TRACING(
+          gpr_log(GPR_ERROR,
+                  "grpc_chttp2_stream disbanded before CONTINUATION received"));
+      return init_skip_frame_parser(exec_ctx, t, 1);
     }
-    if (transport_parsing->is_client) {
-      if ((transport_parsing->incoming_stream_id & 1) &&
-          transport_parsing->incoming_stream_id <
-              transport_parsing->next_stream_id) {
+    if (t->is_client) {
+      if ((t->incoming_stream_id & 1) &&
+          t->incoming_stream_id < t->next_stream_id) {
         /* this is an old (probably cancelled) grpc_chttp2_stream */
       } else {
-        gpr_log(GPR_ERROR,
-                "ignoring new grpc_chttp2_stream creation on client");
+        GRPC_CHTTP2_IF_TRACING(gpr_log(
+            GPR_ERROR, "ignoring new grpc_chttp2_stream creation on client"));
       }
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 1);
-    } else if (transport_parsing->last_incoming_stream_id >
-               transport_parsing->incoming_stream_id) {
-      gpr_log(GPR_ERROR,
-              "ignoring out of order new grpc_chttp2_stream request on server; "
-              "last grpc_chttp2_stream "
-              "id=%d, new grpc_chttp2_stream id=%d",
-              transport_parsing->last_incoming_stream_id,
-              transport_parsing->incoming_stream_id);
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 1);
-    } else if ((transport_parsing->incoming_stream_id & 1) == 0) {
-      gpr_log(GPR_ERROR,
-              "ignoring grpc_chttp2_stream with non-client generated index %d",
-              transport_parsing->incoming_stream_id);
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 1);
+      return init_skip_frame_parser(exec_ctx, t, 1);
+    } else if (t->last_new_stream_id >= t->incoming_stream_id) {
+      GRPC_CHTTP2_IF_TRACING(gpr_log(
+          GPR_ERROR,
+          "ignoring out of order new grpc_chttp2_stream request on server; "
+          "last grpc_chttp2_stream "
+          "id=%d, new grpc_chttp2_stream id=%d",
+          t->last_new_stream_id, t->incoming_stream_id));
+      return init_skip_frame_parser(exec_ctx, t, 1);
+    } else if ((t->incoming_stream_id & 1) == 0) {
+      GRPC_CHTTP2_IF_TRACING(gpr_log(
+          GPR_ERROR,
+          "ignoring grpc_chttp2_stream with non-client generated index %d",
+          t->incoming_stream_id));
+      return init_skip_frame_parser(exec_ctx, t, 1);
     }
-    stream_parsing = transport_parsing->incoming_stream =
-        grpc_chttp2_parsing_accept_stream(
-            exec_ctx, transport_parsing, transport_parsing->incoming_stream_id);
-    if (stream_parsing == NULL) {
-      gpr_log(GPR_ERROR, "grpc_chttp2_stream not accepted");
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 1);
+    t->last_new_stream_id = t->incoming_stream_id;
+    s = t->incoming_stream =
+        grpc_chttp2_parsing_accept_stream(exec_ctx, t, t->incoming_stream_id);
+    if (s == NULL) {
+      GRPC_CHTTP2_IF_TRACING(
+          gpr_log(GPR_ERROR, "grpc_chttp2_stream not accepted"));
+      return init_skip_frame_parser(exec_ctx, t, 1);
     }
-    via_accept = 1;
   } else {
-    transport_parsing->incoming_stream = stream_parsing;
-  }
-  GPR_ASSERT(stream_parsing != NULL && (via_accept == 0 || via_accept == 1));
-  stream_parsing->stats.incoming.framing_bytes += 9;
-  if (stream_parsing->received_close) {
-    gpr_log(GPR_ERROR, "skipping already closed grpc_chttp2_stream header");
-    transport_parsing->incoming_stream = NULL;
-    return init_skip_frame_parser(exec_ctx, transport_parsing, 1);
-  }
-  transport_parsing->parser = grpc_chttp2_header_parser_parse;
-  transport_parsing->parser_data = &transport_parsing->hpack_parser;
-  switch (stream_parsing->header_frames_received) {
+    t->incoming_stream = s;
+  }
+  GPR_ASSERT(s != NULL);
+  s->stats.incoming.framing_bytes += 9;
+  if (s->read_closed) {
+    GRPC_CHTTP2_IF_TRACING(gpr_log(
+        GPR_ERROR, "skipping already closed grpc_chttp2_stream header"));
+    t->incoming_stream = NULL;
+    return init_skip_frame_parser(exec_ctx, t, 1);
+  }
+  t->parser = grpc_chttp2_header_parser_parse;
+  t->parser_data = &t->hpack_parser;
+  switch (s->header_frames_received) {
     case 0:
-      transport_parsing->hpack_parser.on_header = on_initial_header;
+      t->hpack_parser.on_header = on_initial_header;
       break;
     case 1:
-      transport_parsing->hpack_parser.on_header = on_trailing_header;
+      t->hpack_parser.on_header = on_trailing_header;
       break;
     case 2:
       gpr_log(GPR_ERROR, "too many header frames received");
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 1);
+      return init_skip_frame_parser(exec_ctx, t, 1);
   }
-  transport_parsing->hpack_parser.on_header_user_data = transport_parsing;
-  transport_parsing->hpack_parser.is_boundary = is_eoh;
-  transport_parsing->hpack_parser.is_eof =
-      (uint8_t)(is_eoh ? transport_parsing->header_eof : 0);
-  if (!is_continuation && (transport_parsing->incoming_frame_flags &
-                           GRPC_CHTTP2_FLAG_HAS_PRIORITY)) {
-    grpc_chttp2_hpack_parser_set_has_priority(&transport_parsing->hpack_parser);
+  t->hpack_parser.on_header_user_data = t;
+  t->hpack_parser.is_boundary = is_eoh;
+  t->hpack_parser.is_eof = (uint8_t)(is_eoh ? t->header_eof : 0);
+  if (!is_continuation &&
+      (t->incoming_frame_flags & GRPC_CHTTP2_FLAG_HAS_PRIORITY)) {
+    grpc_chttp2_hpack_parser_set_has_priority(&t->hpack_parser);
   }
   return GRPC_ERROR_NONE;
 }
 
-static grpc_error *init_window_update_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
+static grpc_error *init_window_update_frame_parser(grpc_exec_ctx *exec_ctx,
+                                                   grpc_chttp2_transport *t) {
   grpc_error *err = grpc_chttp2_window_update_parser_begin_frame(
-      &transport_parsing->simple.window_update,
-      transport_parsing->incoming_frame_size,
-      transport_parsing->incoming_frame_flags);
+      &t->simple.window_update, t->incoming_frame_size,
+      t->incoming_frame_flags);
   if (err != GRPC_ERROR_NONE) return err;
-  if (transport_parsing->incoming_stream_id != 0) {
-    grpc_chttp2_stream_parsing *stream_parsing =
-        transport_parsing->incoming_stream = grpc_chttp2_parsing_lookup_stream(
-            transport_parsing, transport_parsing->incoming_stream_id);
-    if (stream_parsing == NULL) {
-      return init_skip_frame_parser(exec_ctx, transport_parsing, 0);
+  if (t->incoming_stream_id != 0) {
+    grpc_chttp2_stream *s = t->incoming_stream =
+        grpc_chttp2_parsing_lookup_stream(t, t->incoming_stream_id);
+    if (s == NULL) {
+      return init_skip_frame_parser(exec_ctx, t, 0);
     }
-    stream_parsing->stats.incoming.framing_bytes += 9;
+    s->stats.incoming.framing_bytes += 9;
   }
-  transport_parsing->parser = grpc_chttp2_window_update_parser_parse;
-  transport_parsing->parser_data = &transport_parsing->simple.window_update;
+  t->parser = grpc_chttp2_window_update_parser_parse;
+  t->parser_data = &t->simple.window_update;
   return GRPC_ERROR_NONE;
 }
 
-static grpc_error *init_ping_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
+static grpc_error *init_ping_parser(grpc_exec_ctx *exec_ctx,
+                                    grpc_chttp2_transport *t) {
   grpc_error *err = grpc_chttp2_ping_parser_begin_frame(
-      &transport_parsing->simple.ping, transport_parsing->incoming_frame_size,
-      transport_parsing->incoming_frame_flags);
+      &t->simple.ping, t->incoming_frame_size, t->incoming_frame_flags);
   if (err != GRPC_ERROR_NONE) return err;
-  transport_parsing->parser = grpc_chttp2_ping_parser_parse;
-  transport_parsing->parser_data = &transport_parsing->simple.ping;
+  t->parser = grpc_chttp2_ping_parser_parse;
+  t->parser_data = &t->simple.ping;
   return GRPC_ERROR_NONE;
 }
 
-static grpc_error *init_rst_stream_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
+static grpc_error *init_rst_stream_parser(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t) {
   grpc_error *err = grpc_chttp2_rst_stream_parser_begin_frame(
-      &transport_parsing->simple.rst_stream,
-      transport_parsing->incoming_frame_size,
-      transport_parsing->incoming_frame_flags);
+      &t->simple.rst_stream, t->incoming_frame_size, t->incoming_frame_flags);
   if (err != GRPC_ERROR_NONE) return err;
-  grpc_chttp2_stream_parsing *stream_parsing =
-      transport_parsing->incoming_stream = grpc_chttp2_parsing_lookup_stream(
-          transport_parsing, transport_parsing->incoming_stream_id);
-  if (!transport_parsing->incoming_stream) {
-    return init_skip_frame_parser(exec_ctx, transport_parsing, 0);
-  }
-  stream_parsing->stats.incoming.framing_bytes += 9;
-  transport_parsing->parser = grpc_chttp2_rst_stream_parser_parse;
-  transport_parsing->parser_data = &transport_parsing->simple.rst_stream;
+  grpc_chttp2_stream *s = t->incoming_stream =
+      grpc_chttp2_parsing_lookup_stream(t, t->incoming_stream_id);
+  if (!t->incoming_stream) {
+    return init_skip_frame_parser(exec_ctx, t, 0);
+  }
+  s->stats.incoming.framing_bytes += 9;
+  t->parser = grpc_chttp2_rst_stream_parser_parse;
+  t->parser_data = &t->simple.rst_stream;
   return GRPC_ERROR_NONE;
 }
 
-static grpc_error *init_goaway_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
+static grpc_error *init_goaway_parser(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_transport *t) {
   grpc_error *err = grpc_chttp2_goaway_parser_begin_frame(
-      &transport_parsing->goaway_parser, transport_parsing->incoming_frame_size,
-      transport_parsing->incoming_frame_flags);
+      &t->goaway_parser, t->incoming_frame_size, t->incoming_frame_flags);
   if (err != GRPC_ERROR_NONE) return err;
-  transport_parsing->parser = grpc_chttp2_goaway_parser_parse;
-  transport_parsing->parser_data = &transport_parsing->goaway_parser;
+  t->parser = grpc_chttp2_goaway_parser_parse;
+  t->parser_data = &t->goaway_parser;
   return GRPC_ERROR_NONE;
 }
 
-static grpc_error *init_settings_frame_parser(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing) {
-  if (transport_parsing->incoming_stream_id != 0) {
+static grpc_error *init_settings_frame_parser(grpc_exec_ctx *exec_ctx,
+                                              grpc_chttp2_transport *t) {
+  if (t->incoming_stream_id != 0) {
     return GRPC_ERROR_CREATE("Settings frame received for grpc_chttp2_stream");
   }
 
   grpc_error *err = grpc_chttp2_settings_parser_begin_frame(
-      &transport_parsing->simple.settings,
-      transport_parsing->incoming_frame_size,
-      transport_parsing->incoming_frame_flags, transport_parsing->settings);
+      &t->simple.settings, t->incoming_frame_size, t->incoming_frame_flags,
+      t->settings[GRPC_PEER_SETTINGS]);
   if (err != GRPC_ERROR_NONE) {
     return err;
   }
-  if (transport_parsing->incoming_frame_flags & GRPC_CHTTP2_FLAG_ACK) {
-    transport_parsing->settings_ack_received = 1;
+  if (t->incoming_frame_flags & GRPC_CHTTP2_FLAG_ACK) {
+    memcpy(t->settings[GRPC_ACKED_SETTINGS], t->settings[GRPC_SENT_SETTINGS],
+           GRPC_CHTTP2_NUM_SETTINGS * sizeof(uint32_t));
     grpc_chttp2_hptbl_set_max_bytes(
-        &transport_parsing->hpack_parser.table,
-        transport_parsing
-            ->last_sent_settings[GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE]);
-    transport_parsing->max_frame_size =
-        transport_parsing
-            ->last_sent_settings[GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE];
+        &t->hpack_parser.table,
+        t->settings[GRPC_ACKED_SETTINGS]
+                   [GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE]);
+    t->sent_local_settings = 0;
   }
-  transport_parsing->parser = grpc_chttp2_settings_parser_parse;
-  transport_parsing->parser_data = &transport_parsing->simple.settings;
+  t->parser = grpc_chttp2_settings_parser_parse;
+  t->parser_data = &t->simple.settings;
   return GRPC_ERROR_NONE;
 }
 
-/*
-static int is_window_update_legal(int64_t window_update, int64_t window) {
-  return window + window_update < MAX_WINDOW;
-}
-*/
-
-static grpc_error *parse_frame_slice(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_parsing *transport_parsing,
-    gpr_slice slice, int is_last) {
-  grpc_chttp2_stream_parsing *stream_parsing =
-      transport_parsing->incoming_stream;
-  grpc_error *err = transport_parsing->parser(
-      exec_ctx, transport_parsing->parser_data, transport_parsing,
-      stream_parsing, slice, is_last);
+static grpc_error *parse_frame_slice(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_transport *t, gpr_slice slice,
+                                     int is_last) {
+  grpc_chttp2_stream *s = t->incoming_stream;
+  grpc_error *err = t->parser(exec_ctx, t->parser_data, t, s, slice, is_last);
   if (err == GRPC_ERROR_NONE) {
-    if (stream_parsing) {
-      grpc_chttp2_list_add_parsing_seen_stream(transport_parsing,
-                                               stream_parsing);
-    }
-    return GRPC_ERROR_NONE;
+    return err;
   } else if (grpc_error_get_int(err, GRPC_ERROR_INT_STREAM_ID, NULL)) {
     if (grpc_http_trace) {
       const char *msg = grpc_error_string(err);
       gpr_log(GPR_ERROR, "%s", msg);
       grpc_error_free_string(msg);
     }
-    grpc_chttp2_parsing_become_skip_parser(exec_ctx, transport_parsing);
-    if (stream_parsing) {
-      stream_parsing->forced_close_error = err;
+    grpc_chttp2_parsing_become_skip_parser(exec_ctx, t);
+    if (s) {
+      s->forced_close_error = err;
       gpr_slice_buffer_add(
-          &transport_parsing->qbuf,
-          grpc_chttp2_rst_stream_create(transport_parsing->incoming_stream_id,
-                                        GRPC_CHTTP2_PROTOCOL_ERROR,
-                                        &stream_parsing->stats.outgoing));
+          &t->qbuf, grpc_chttp2_rst_stream_create(t->incoming_stream_id,
+                                                  GRPC_CHTTP2_PROTOCOL_ERROR,
+                                                  &s->stats.outgoing));
     } else {
       GRPC_ERROR_UNREF(err);
     }

src/core/ext/transport/chttp2/transport/stream_lists.c

@@ -35,27 +35,6 @@
 
 #include <grpc/support/log.h>
 
-#define TRANSPORT_FROM_GLOBAL(tg)                                         \
-  ((grpc_chttp2_transport *)((char *)(tg)-offsetof(grpc_chttp2_transport, \
-                                                   global)))
-
-#define STREAM_FROM_GLOBAL(sg) \
-  ((grpc_chttp2_stream *)((char *)(sg)-offsetof(grpc_chttp2_stream, global)))
-
-#define TRANSPORT_FROM_WRITING(tw)                                        \
-  ((grpc_chttp2_transport *)((char *)(tw)-offsetof(grpc_chttp2_transport, \
-                                                   writing)))
-
-#define STREAM_FROM_WRITING(sw) \
-  ((grpc_chttp2_stream *)((char *)(sw)-offsetof(grpc_chttp2_stream, writing)))
-
-#define TRANSPORT_FROM_PARSING(tp)                                        \
-  ((grpc_chttp2_transport *)((char *)(tp)-offsetof(grpc_chttp2_transport, \
-                                                   parsing)))
-
-#define STREAM_FROM_PARSING(sp) \
-  ((grpc_chttp2_stream *)((char *)(sp)-offsetof(grpc_chttp2_stream, parsing)))
-
 /* core list management */
 
 static int stream_list_empty(grpc_chttp2_transport *t,
@@ -139,314 +118,57 @@ static bool stream_list_add(grpc_chttp2_transport *t, grpc_chttp2_stream *s,
 
 /* wrappers for specializations */
 
-bool grpc_chttp2_list_add_writable_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  GPR_ASSERT(stream_global->id != 0);
-  return stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
-                         STREAM_FROM_GLOBAL(stream_global),
-                         GRPC_CHTTP2_LIST_WRITABLE);
-}
-
-int grpc_chttp2_list_pop_writable_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_writing **stream_writing) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                          GRPC_CHTTP2_LIST_WRITABLE);
-  if (r != 0) {
-    *stream_global = &stream->global;
-    *stream_writing = &stream->writing;
-  }
-  return r;
-}
-
-bool grpc_chttp2_list_remove_writable_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  return stream_list_maybe_remove(TRANSPORT_FROM_GLOBAL(transport_global),
-                                  STREAM_FROM_GLOBAL(stream_global),
-                                  GRPC_CHTTP2_LIST_WRITABLE);
-}
-
-void grpc_chttp2_list_add_writing_stream(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing) {
-  GPR_ASSERT(stream_list_add(TRANSPORT_FROM_WRITING(transport_writing),
-                             STREAM_FROM_WRITING(stream_writing),
-                             GRPC_CHTTP2_LIST_WRITING));
-}
-
-int grpc_chttp2_list_have_writing_streams(
-    grpc_chttp2_transport_writing *transport_writing) {
-  return !stream_list_empty(TRANSPORT_FROM_WRITING(transport_writing),
-                            GRPC_CHTTP2_LIST_WRITING);
+bool grpc_chttp2_list_add_writable_stream(grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s) {
+  GPR_ASSERT(s->id != 0);
+  return stream_list_add(t, s, GRPC_CHTTP2_LIST_WRITABLE);
 }
 
-int grpc_chttp2_list_pop_writing_stream(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing **stream_writing) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_WRITING(transport_writing), &stream,
-                          GRPC_CHTTP2_LIST_WRITING);
-  if (r != 0) {
-    *stream_writing = &stream->writing;
-  }
-  return r;
-}
-
-void grpc_chttp2_list_add_written_stream(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing) {
-  stream_list_add(TRANSPORT_FROM_WRITING(transport_writing),
-                  STREAM_FROM_WRITING(stream_writing),
-                  GRPC_CHTTP2_LIST_WRITTEN);
+int grpc_chttp2_list_pop_writable_stream(grpc_chttp2_transport *t,
+                                         grpc_chttp2_stream **s) {
+  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_WRITABLE);
 }
 
-int grpc_chttp2_list_pop_written_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_writing **stream_writing) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_WRITING(transport_writing), &stream,
-                          GRPC_CHTTP2_LIST_WRITTEN);
-  if (r != 0) {
-    *stream_global = &stream->global;
-    *stream_writing = &stream->writing;
-  }
-  return r;
+bool grpc_chttp2_list_remove_writable_stream(grpc_chttp2_transport *t,
+                                             grpc_chttp2_stream *s) {
+  return stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_WRITABLE);
 }
 
-void grpc_chttp2_list_add_unannounced_incoming_window_available(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  GPR_ASSERT(stream_global->id != 0);
-  stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
-                  STREAM_FROM_GLOBAL(stream_global),
-                  GRPC_CHTTP2_LIST_UNANNOUNCED_INCOMING_WINDOW_AVAILABLE);
+bool grpc_chttp2_list_add_writing_stream(grpc_chttp2_transport *t,
+                                         grpc_chttp2_stream *s) {
+  return stream_list_add(t, s, GRPC_CHTTP2_LIST_WRITING);
 }
 
-void grpc_chttp2_list_remove_unannounced_incoming_window_available(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  stream_list_maybe_remove(
-      TRANSPORT_FROM_GLOBAL(transport_global),
-      STREAM_FROM_GLOBAL(stream_global),
-      GRPC_CHTTP2_LIST_UNANNOUNCED_INCOMING_WINDOW_AVAILABLE);
+int grpc_chttp2_list_have_writing_streams(grpc_chttp2_transport *t) {
+  return !stream_list_empty(t, GRPC_CHTTP2_LIST_WRITING);
 }
 
-int grpc_chttp2_list_pop_unannounced_incoming_window_available(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_parsing **stream_parsing) {
-  grpc_chttp2_stream *stream;
-  int r =
-      stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                      GRPC_CHTTP2_LIST_UNANNOUNCED_INCOMING_WINDOW_AVAILABLE);
-  if (r != 0) {
-    *stream_global = &stream->global;
-    *stream_parsing = &stream->parsing;
-  }
-  return r;
+int grpc_chttp2_list_pop_writing_stream(grpc_chttp2_transport *t,
+                                        grpc_chttp2_stream **s) {
+  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_WRITING);
 }
 
-void grpc_chttp2_list_add_parsing_seen_stream(
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_parsing *stream_parsing) {
-  stream_list_add(TRANSPORT_FROM_PARSING(transport_parsing),
-                  STREAM_FROM_PARSING(stream_parsing),
-                  GRPC_CHTTP2_LIST_PARSING_SEEN);
+void grpc_chttp2_list_add_waiting_for_concurrency(grpc_chttp2_transport *t,
+                                                  grpc_chttp2_stream *s) {
+  stream_list_add(t, s, GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY);
 }
 
-int grpc_chttp2_list_pop_parsing_seen_stream(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_parsing *transport_parsing,
-    grpc_chttp2_stream_global **stream_global,
-    grpc_chttp2_stream_parsing **stream_parsing) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_PARSING(transport_parsing), &stream,
-                          GRPC_CHTTP2_LIST_PARSING_SEEN);
-  if (r != 0) {
-    *stream_global = &stream->global;
-    *stream_parsing = &stream->parsing;
-  }
-  return r;
+int grpc_chttp2_list_pop_waiting_for_concurrency(grpc_chttp2_transport *t,
+                                                 grpc_chttp2_stream **s) {
+  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY);
 }
 
-void grpc_chttp2_list_add_waiting_for_concurrency(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
-                  STREAM_FROM_GLOBAL(stream_global),
-                  GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY);
+void grpc_chttp2_list_add_stalled_by_transport(grpc_chttp2_transport *t,
+                                               grpc_chttp2_stream *s) {
+  stream_list_add(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
 }
 
-int grpc_chttp2_list_pop_waiting_for_concurrency(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                          GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY);
-  if (r != 0) {
-    *stream_global = &stream->global;
-  }
-  return r;
+int grpc_chttp2_list_pop_stalled_by_transport(grpc_chttp2_transport *t,
+                                              grpc_chttp2_stream **s) {
+  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
 }
 
-void grpc_chttp2_list_add_check_read_ops(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
-                  STREAM_FROM_GLOBAL(stream_global),
-                  GRPC_CHTTP2_LIST_CHECK_READ_OPS);
-}
-
-bool grpc_chttp2_list_remove_check_read_ops(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  return stream_list_maybe_remove(TRANSPORT_FROM_GLOBAL(transport_global),
-                                  STREAM_FROM_GLOBAL(stream_global),
-                                  GRPC_CHTTP2_LIST_CHECK_READ_OPS);
-}
-
-int grpc_chttp2_list_pop_check_read_ops(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                          GRPC_CHTTP2_LIST_CHECK_READ_OPS);
-  if (r != 0) {
-    *stream_global = &stream->global;
-  }
-  return r;
-}
-
-void grpc_chttp2_list_add_writing_stalled_by_transport(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing) {
-  grpc_chttp2_stream *stream = STREAM_FROM_WRITING(stream_writing);
-  gpr_log(GPR_DEBUG, "writing stalled %d", stream->global.id);
-  if (!stream->included[GRPC_CHTTP2_LIST_WRITING_STALLED_BY_TRANSPORT]) {
-    GRPC_CHTTP2_STREAM_REF(&stream->global, "chttp2_writing_stalled");
-  }
-  stream_list_add(TRANSPORT_FROM_WRITING(transport_writing), stream,
-                  GRPC_CHTTP2_LIST_WRITING_STALLED_BY_TRANSPORT);
-}
-
-bool grpc_chttp2_list_flush_writing_stalled_by_transport(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_writing *transport_writing) {
-  grpc_chttp2_stream *stream;
-  bool out = false;
-  grpc_chttp2_transport *transport = TRANSPORT_FROM_WRITING(transport_writing);
-  while (stream_list_pop(transport, &stream,
-                         GRPC_CHTTP2_LIST_WRITING_STALLED_BY_TRANSPORT)) {
-    gpr_log(GPR_DEBUG, "move %d from writing stalled to just stalled",
-            stream->global.id);
-    grpc_chttp2_list_add_stalled_by_transport(transport_writing,
-                                              &stream->writing);
-    GRPC_CHTTP2_STREAM_UNREF(exec_ctx, &stream->global,
-                             "chttp2_writing_stalled");
-    out = true;
-  }
-  return out;
-}
-
-void grpc_chttp2_list_add_stalled_by_transport(
-    grpc_chttp2_transport_writing *transport_writing,
-    grpc_chttp2_stream_writing *stream_writing) {
-  gpr_log(GPR_DEBUG, "stalled %d", stream_writing->id);
-  stream_list_add(TRANSPORT_FROM_WRITING(transport_writing),
-                  STREAM_FROM_WRITING(stream_writing),
-                  GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
-}
-
-int grpc_chttp2_list_pop_stalled_by_transport(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                          GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
-  if (r != 0) {
-    *stream_global = &stream->global;
-  }
-  return r;
-}
-
-void grpc_chttp2_list_remove_stalled_by_transport(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  stream_list_maybe_remove(TRANSPORT_FROM_GLOBAL(transport_global),
-                           STREAM_FROM_GLOBAL(stream_global),
-                           GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
-}
-
-void grpc_chttp2_list_add_closed_waiting_for_parsing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
-                  STREAM_FROM_GLOBAL(stream_global),
-                  GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_PARSING);
-}
-
-int grpc_chttp2_list_pop_closed_waiting_for_parsing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                          GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_PARSING);
-  if (r != 0) {
-    *stream_global = &stream->global;
-  }
-  return r;
-}
-
-void grpc_chttp2_list_add_closed_waiting_for_writing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global *stream_global) {
-  stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
-                  STREAM_FROM_GLOBAL(stream_global),
-                  GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_WRITING);
-}
-
-int grpc_chttp2_list_pop_closed_waiting_for_writing(
-    grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_stream_global **stream_global) {
-  grpc_chttp2_stream *stream;
-  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
-                          GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_WRITING);
-  if (r != 0) {
-    *stream_global = &stream->global;
-  }
-  return r;
-}
-
-void grpc_chttp2_register_stream(grpc_chttp2_transport *t,
-                                 grpc_chttp2_stream *s) {
-  stream_list_add_tail(t, s, GRPC_CHTTP2_LIST_ALL_STREAMS);
-}
-
-int grpc_chttp2_unregister_stream(grpc_chttp2_transport *t,
-                                  grpc_chttp2_stream *s) {
-  stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_ALL_STREAMS);
-  return stream_list_empty(t, GRPC_CHTTP2_LIST_ALL_STREAMS);
-}
-
-int grpc_chttp2_has_streams(grpc_chttp2_transport *t) {
-  return !stream_list_empty(t, GRPC_CHTTP2_LIST_ALL_STREAMS);
-}
-
-void grpc_chttp2_for_all_streams(
-    grpc_chttp2_transport_global *transport_global, void *user_data,
-    void (*cb)(grpc_chttp2_transport_global *transport_global, void *user_data,
-               grpc_chttp2_stream_global *stream_global)) {
-  grpc_chttp2_stream *s;
-  grpc_chttp2_transport *t = TRANSPORT_FROM_GLOBAL(transport_global);
-  for (s = t->lists[GRPC_CHTTP2_LIST_ALL_STREAMS].head; s != NULL;
-       s = s->links[GRPC_CHTTP2_LIST_ALL_STREAMS].next) {
-    cb(transport_global, user_data, &s->global);
-  }
+void grpc_chttp2_list_remove_stalled_by_transport(grpc_chttp2_transport *t,
+                                                  grpc_chttp2_stream *s) {
+  stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
 }

src/core/ext/transport/chttp2/transport/stream_map.c

@@ -77,6 +77,7 @@ void grpc_chttp2_stream_map_add(grpc_chttp2_stream_map *map, uint32_t key,
 
   GPR_ASSERT(count == 0 || keys[count - 1] < key);
   GPR_ASSERT(value);
+  GPR_ASSERT(grpc_chttp2_stream_map_find(map, key) == NULL);
 
   if (count == capacity) {
     if (map->free > capacity / 4) {
@@ -96,40 +97,6 @@ void grpc_chttp2_stream_map_add(grpc_chttp2_stream_map *map, uint32_t key,
   map->count = count + 1;
 }
 
-void grpc_chttp2_stream_map_move_into(grpc_chttp2_stream_map *src,
-                                      grpc_chttp2_stream_map *dst) {
-  /* if src is empty we dont need to do anything */
-  if (src->count == src->free) {
-    return;
-  }
-  /* if dst is empty we simply need to swap */
-  if (dst->count == dst->free) {
-    GPR_SWAP(grpc_chttp2_stream_map, *src, *dst);
-    return;
-  }
-  /* the first element of src must be greater than the last of dst...
-   * however the maps may need compacting for this property to hold */
-  if (src->keys[0] <= dst->keys[dst->count - 1]) {
-    src->count = compact(src->keys, src->values, src->count);
-    src->free = 0;
-    dst->count = compact(dst->keys, dst->values, dst->count);
-    dst->free = 0;
-  }
-  GPR_ASSERT(src->keys[0] > dst->keys[dst->count - 1]);
-  /* if dst doesn't have capacity, resize */
-  if (dst->count + src->count > dst->capacity) {
-    dst->capacity = GPR_MAX(dst->capacity * 3 / 2, dst->count + src->count);
-    dst->keys = gpr_realloc(dst->keys, dst->capacity * sizeof(uint32_t));
-    dst->values = gpr_realloc(dst->values, dst->capacity * sizeof(void *));
-  }
-  memcpy(dst->keys + dst->count, src->keys, src->count * sizeof(uint32_t));
-  memcpy(dst->values + dst->count, src->values, src->count * sizeof(void *));
-  dst->count += src->count;
-  dst->free += src->free;
-  src->count = 0;
-  src->free = 0;
-}
-
 static void **find(grpc_chttp2_stream_map *map, uint32_t key) {
   size_t min_idx = 0;
   size_t max_idx = map->count;
@@ -170,6 +137,7 @@ void *grpc_chttp2_stream_map_delete(grpc_chttp2_stream_map *map, uint32_t key) {
     if (map->free == map->count) {
       map->free = map->count = 0;
     }
+    GPR_ASSERT(grpc_chttp2_stream_map_find(map, key) == NULL);
   }
   return out;
 }

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

@@ -65,10 +65,6 @@ void grpc_chttp2_stream_map_add(grpc_chttp2_stream_map *map, uint32_t key,
    or NULL otherwise */
 void *grpc_chttp2_stream_map_delete(grpc_chttp2_stream_map *map, uint32_t key);
 
-/* Move all elements of src into dst */
-void grpc_chttp2_stream_map_move_into(grpc_chttp2_stream_map *src,
-                                      grpc_chttp2_stream_map *dst);
-
 /* Return an existing key, or NULL if it does not exist */
 void *grpc_chttp2_stream_map_find(grpc_chttp2_stream_map *map, uint32_t key);
 

src/core/ext/transport/chttp2/transport/writing.c

@@ -40,346 +40,215 @@
 #include "src/core/ext/transport/chttp2/transport/http2_errors.h"
 #include "src/core/lib/profiling/timers.h"
 
-static void finalize_outbuf(grpc_exec_ctx *exec_ctx,
-                            grpc_chttp2_transport_writing *transport_writing);
+static void add_to_write_list(grpc_chttp2_write_cb **list,
+                              grpc_chttp2_write_cb *cb) {
+  cb->next = *list;
+  *list = cb;
+}
 
-int grpc_chttp2_unlocking_check_writes(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing) {
-  grpc_chttp2_stream_global *stream_global;
-  grpc_chttp2_stream_writing *stream_writing;
+static void finish_write_cb(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+                            grpc_chttp2_stream *s, grpc_chttp2_write_cb *cb,
+                            grpc_error *error) {
+  grpc_chttp2_complete_closure_step(exec_ctx, t, s, &cb->closure, error,
+                                    "finish_write_cb");
+  cb->next = t->write_cb_pool;
+  t->write_cb_pool = cb;
+}
 
-  GPR_TIMER_BEGIN("grpc_chttp2_unlocking_check_writes", 0);
+static void update_list(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+                        grpc_chttp2_stream *s, size_t send_bytes,
+                        grpc_chttp2_write_cb **list, grpc_error *error) {
+  grpc_chttp2_write_cb *cb = *list;
+  *list = NULL;
+  while (cb) {
+    grpc_chttp2_write_cb *next = cb->next;
+    if (cb->call_at_byte <= send_bytes) {
+      finish_write_cb(exec_ctx, t, s, cb, GRPC_ERROR_REF(error));
+    } else {
+      cb->call_at_byte -= send_bytes;
+      add_to_write_list(list, cb);
+    }
+    cb = next;
+  }
+}
 
-  transport_writing->max_frame_size =
-      transport_global->settings[GRPC_ACKED_SETTINGS]
-                                [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE];
+bool grpc_chttp2_begin_write(grpc_exec_ctx *exec_ctx,
+                             grpc_chttp2_transport *t) {
+  grpc_chttp2_stream *s;
 
-  /* simple writes are queued to qbuf, and flushed here */
-  gpr_slice_buffer_swap(&transport_global->qbuf, &transport_writing->outbuf);
-  GPR_ASSERT(transport_global->qbuf.count == 0);
+  GPR_TIMER_BEGIN("grpc_chttp2_begin_write", 0);
 
-  grpc_chttp2_hpack_compressor_set_max_table_size(
-      &transport_writing->hpack_compressor,
-      transport_global->settings[GRPC_PEER_SETTINGS]
-                                [GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE]);
-
-  if (transport_global->dirtied_local_settings &&
-      !transport_global->sent_local_settings) {
+  if (t->dirtied_local_settings && !t->sent_local_settings) {
     gpr_slice_buffer_add(
-        &transport_writing->outbuf,
+        &t->outbuf,
         grpc_chttp2_settings_create(
-            transport_global->settings[GRPC_SENT_SETTINGS],
-            transport_global->settings[GRPC_LOCAL_SETTINGS],
-            transport_global->force_send_settings, GRPC_CHTTP2_NUM_SETTINGS));
-    transport_global->force_send_settings = 0;
-    transport_global->dirtied_local_settings = 0;
-    transport_global->sent_local_settings = 1;
+            t->settings[GRPC_SENT_SETTINGS], t->settings[GRPC_LOCAL_SETTINGS],
+            t->force_send_settings, GRPC_CHTTP2_NUM_SETTINGS));
+    t->force_send_settings = 0;
+    t->dirtied_local_settings = 0;
+    t->sent_local_settings = 1;
   }
 
-  GRPC_CHTTP2_FLOW_MOVE_TRANSPORT("write", transport_writing, outgoing_window,
-                                  transport_global, outgoing_window);
-  if (transport_writing->outgoing_window > 0) {
-    while (grpc_chttp2_list_pop_stalled_by_transport(transport_global,
-                                                     &stream_global)) {
-      grpc_chttp2_become_writable(exec_ctx, transport_global, stream_global,
-                                  false, "transport.read_flow_control");
+  /* simple writes are queued to qbuf, and flushed here */
+  gpr_slice_buffer_move_into(&t->qbuf, &t->outbuf);
+  GPR_ASSERT(t->qbuf.count == 0);
+
+  grpc_chttp2_hpack_compressor_set_max_table_size(
+      &t->hpack_compressor,
+      t->settings[GRPC_PEER_SETTINGS][GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE]);
+
+  if (t->outgoing_window > 0) {
+    while (grpc_chttp2_list_pop_stalled_by_transport(t, &s)) {
+      grpc_chttp2_become_writable(exec_ctx, t, s, false,
+                                  "transport.read_flow_control");
     }
   }
 
   /* for each grpc_chttp2_stream that's become writable, frame it's data
      (according to available window sizes) and add to the output buffer */
-  while (grpc_chttp2_list_pop_writable_stream(
-      transport_global, transport_writing, &stream_global, &stream_writing)) {
-    bool sent_initial_metadata = stream_writing->sent_initial_metadata;
-    bool become_writable = false;
-
-    stream_writing->id = stream_global->id;
-    stream_writing->read_closed = stream_global->read_closed;
+  while (grpc_chttp2_list_pop_writable_stream(t, &s)) {
+    bool sent_initial_metadata = s->sent_initial_metadata;
+    bool now_writing = false;
 
-    GRPC_CHTTP2_FLOW_MOVE_STREAM("write", transport_writing, stream_writing,
-                                 outgoing_window, stream_global,
-                                 outgoing_window);
+    GRPC_CHTTP2_IF_TRACING(gpr_log(
+        GPR_DEBUG, "W:%p %s[%d] im-(sent,send)=(%d,%d) announce=%d", t,
+        t->is_client ? "CLIENT" : "SERVER", s->id, sent_initial_metadata,
+        s->send_initial_metadata != NULL, s->announce_window));
 
-    if (!sent_initial_metadata && stream_global->send_initial_metadata) {
-      stream_writing->send_initial_metadata =
-          stream_global->send_initial_metadata;
-      stream_global->send_initial_metadata = NULL;
-      become_writable = true;
+    /* send initial metadata if it's available */
+    if (!sent_initial_metadata && s->send_initial_metadata) {
+      grpc_chttp2_encode_header(
+          &t->hpack_compressor, s->id, s->send_initial_metadata, 0,
+          t->settings[GRPC_ACKED_SETTINGS][GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
+          &s->stats.outgoing, &t->outbuf);
+      s->send_initial_metadata = NULL;
+      s->sent_initial_metadata = true;
       sent_initial_metadata = true;
+      now_writing = true;
+    }
+    /* send any window updates */
+    if (s->announce_window > 0) {
+      uint32_t announce = s->announce_window;
+      gpr_slice_buffer_add(&t->outbuf,
+                           grpc_chttp2_window_update_create(
+                               s->id, s->announce_window, &s->stats.outgoing));
+      GRPC_CHTTP2_FLOW_DEBIT_STREAM("write", t, s, announce_window, announce);
     }
     if (sent_initial_metadata) {
-      if (stream_global->send_message != NULL) {
-        gpr_slice hdr = gpr_slice_malloc(5);
-        uint8_t *p = GPR_SLICE_START_PTR(hdr);
-        uint32_t len = stream_global->send_message->length;
-        GPR_ASSERT(stream_writing->send_message == NULL);
-        p[0] = (stream_global->send_message->flags &
-                GRPC_WRITE_INTERNAL_COMPRESS) != 0;
-        p[1] = (uint8_t)(len >> 24);
-        p[2] = (uint8_t)(len >> 16);
-        p[3] = (uint8_t)(len >> 8);
-        p[4] = (uint8_t)(len);
-        gpr_slice_buffer_add(&stream_writing->flow_controlled_buffer, hdr);
-        if (stream_global->send_message->length > 0) {
-          stream_writing->send_message = stream_global->send_message;
-        } else {
-          stream_writing->send_message = NULL;
+      /* send any body bytes, if allowed by flow control */
+      if (s->flow_controlled_buffer.length > 0) {
+        uint32_t max_outgoing =
+            (uint32_t)GPR_MIN(t->settings[GRPC_ACKED_SETTINGS]
+                                         [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
+                              GPR_MIN(s->outgoing_window, t->outgoing_window));
+        if (max_outgoing > 0) {
+          uint32_t send_bytes =
+              (uint32_t)GPR_MIN(max_outgoing, s->flow_controlled_buffer.length);
+          bool is_last_data_frame =
+              s->fetching_send_message == NULL &&
+              send_bytes == s->flow_controlled_buffer.length;
+          bool is_last_frame =
+              is_last_data_frame && s->send_trailing_metadata != NULL &&
+              grpc_metadata_batch_is_empty(s->send_trailing_metadata);
+          grpc_chttp2_encode_data(s->id, &s->flow_controlled_buffer, send_bytes,
+                                  is_last_frame, &s->stats.outgoing,
+                                  &t->outbuf);
+          GRPC_CHTTP2_FLOW_DEBIT_STREAM("write", t, s, outgoing_window,
+                                        send_bytes);
+          GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("write", t, outgoing_window,
+                                           send_bytes);
+          if (is_last_frame) {
+            s->send_trailing_metadata = NULL;
+            s->sent_trailing_metadata = true;
+            if (!t->is_client && !s->read_closed) {
+              gpr_slice_buffer_add(&t->outbuf, grpc_chttp2_rst_stream_create(
+                                                   s->id, GRPC_CHTTP2_NO_ERROR,
+                                                   &s->stats.outgoing));
+            }
+          }
+          s->sending_bytes += send_bytes;
+          now_writing = true;
+          if (s->flow_controlled_buffer.length > 0) {
+            GRPC_CHTTP2_STREAM_REF(s, "chttp2_writing:fork");
+            grpc_chttp2_list_add_writable_stream(t, s);
+          }
+        } else if (t->outgoing_window == 0) {
+          grpc_chttp2_list_add_stalled_by_transport(t, s);
+          now_writing = true;
         }
-        stream_writing->stream_fetched = 0;
-        stream_global->send_message = NULL;
       }
-      if ((stream_writing->send_message != NULL ||
-           stream_writing->flow_controlled_buffer.length > 0) &&
-          stream_writing->outgoing_window > 0) {
-        if (transport_writing->outgoing_window > 0) {
-          become_writable = true;
-        } else {
-          grpc_chttp2_list_add_stalled_by_transport(transport_writing,
-                                                    stream_writing);
+      if (s->send_trailing_metadata != NULL &&
+          s->fetching_send_message == NULL &&
+          s->flow_controlled_buffer.length == 0) {
+        grpc_chttp2_encode_header(
+            &t->hpack_compressor, s->id, s->send_trailing_metadata, true,
+            t->settings[GRPC_ACKED_SETTINGS]
+                       [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
+            &s->stats.outgoing, &t->outbuf);
+        s->send_trailing_metadata = NULL;
+        s->sent_trailing_metadata = true;
+        if (!t->is_client && !s->read_closed) {
+          gpr_slice_buffer_add(
+              &t->outbuf, grpc_chttp2_rst_stream_create(
+                              s->id, GRPC_CHTTP2_NO_ERROR, &s->stats.outgoing));
         }
+        now_writing = true;
       }
-      if (stream_global->send_trailing_metadata) {
-        stream_writing->send_trailing_metadata =
-            stream_global->send_trailing_metadata;
-        stream_global->send_trailing_metadata = NULL;
-        become_writable = true;
-      }
-    }
-
-    if (!stream_global->read_closed &&
-        stream_global->unannounced_incoming_window_for_writing > 1024) {
-      GRPC_CHTTP2_FLOW_MOVE_STREAM("write", transport_global, stream_writing,
-                                   announce_window, stream_global,
-                                   unannounced_incoming_window_for_writing);
-      become_writable = true;
     }
 
-    if (become_writable) {
-      grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
+    if (now_writing) {
+      if (!grpc_chttp2_list_add_writing_stream(t, s)) {
+        /* already in writing list: drop ref */
+        GRPC_CHTTP2_STREAM_UNREF(exec_ctx, s, "chttp2_writing:already_writing");
+      }
     } else {
-      GRPC_CHTTP2_STREAM_UNREF(exec_ctx, stream_global, "chttp2_writing");
+      GRPC_CHTTP2_STREAM_UNREF(exec_ctx, s, "chttp2_writing:no_write");
     }
   }
 
   /* if the grpc_chttp2_transport is ready to send a window update, do so here
      also; 3/4 is a magic number that will likely get tuned soon */
-  if (transport_global->announce_incoming_window > 0) {
-    uint32_t announced = (uint32_t)GPR_MIN(
-        transport_global->announce_incoming_window, UINT32_MAX);
-    GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("write", transport_global,
-                                     announce_incoming_window, announced);
+  if (t->announce_incoming_window > 0) {
+    uint32_t announced =
+        (uint32_t)GPR_MIN(t->announce_incoming_window, UINT32_MAX);
+    GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("write", t, announce_incoming_window,
+                                     announced);
     grpc_transport_one_way_stats throwaway_stats;
-    gpr_slice_buffer_add(
-        &transport_writing->outbuf,
-        grpc_chttp2_window_update_create(0, announced, &throwaway_stats));
-  }
-
-  GPR_TIMER_END("grpc_chttp2_unlocking_check_writes", 0);
-
-  return transport_writing->outbuf.count > 0 ||
-         grpc_chttp2_list_have_writing_streams(transport_writing);
-}
-
-void grpc_chttp2_perform_writes(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_writing *transport_writing,
-    grpc_endpoint *endpoint) {
-  GPR_ASSERT(transport_writing->outbuf.count > 0 ||
-             grpc_chttp2_list_have_writing_streams(transport_writing));
-
-  finalize_outbuf(exec_ctx, transport_writing);
-
-  GPR_ASSERT(endpoint);
-
-  if (transport_writing->outbuf.count > 0) {
-    grpc_endpoint_write(exec_ctx, endpoint, &transport_writing->outbuf,
-                        &transport_writing->done_cb);
-  } else {
-    grpc_exec_ctx_sched(exec_ctx, &transport_writing->done_cb, GRPC_ERROR_NONE,
-                        NULL);
+    gpr_slice_buffer_add(&t->outbuf, grpc_chttp2_window_update_create(
+                                         0, announced, &throwaway_stats));
   }
-}
-
-static void finalize_outbuf(grpc_exec_ctx *exec_ctx,
-                            grpc_chttp2_transport_writing *transport_writing) {
-  grpc_chttp2_stream_writing *stream_writing;
 
-  GPR_TIMER_BEGIN("finalize_outbuf", 0);
-
-  bool is_first_data_frame = true;
-  while (
-      grpc_chttp2_list_pop_writing_stream(transport_writing, &stream_writing)) {
-    uint32_t max_outgoing =
-        (uint32_t)GPR_MIN(transport_writing->max_frame_size,
-                          GPR_MIN(stream_writing->outgoing_window,
-                                  transport_writing->outgoing_window));
-    /* send initial metadata if it's available */
-    if (stream_writing->send_initial_metadata != NULL) {
-      grpc_chttp2_encode_header(
-          &transport_writing->hpack_compressor, stream_writing->id,
-          stream_writing->send_initial_metadata, 0,
-          transport_writing->max_frame_size, &stream_writing->stats,
-          &transport_writing->outbuf);
-      stream_writing->send_initial_metadata = NULL;
-      stream_writing->sent_initial_metadata = 1;
-    }
-    /* send any window updates */
-    if (stream_writing->announce_window > 0 &&
-        stream_writing->send_initial_metadata == NULL) {
-      uint32_t announce = stream_writing->announce_window;
-      gpr_slice_buffer_add(
-          &transport_writing->outbuf,
-          grpc_chttp2_window_update_create(stream_writing->id,
-                                           stream_writing->announce_window,
-                                           &stream_writing->stats));
-      GRPC_CHTTP2_FLOW_DEBIT_STREAM("write", transport_writing, stream_writing,
-                                    announce_window, announce);
-      stream_writing->announce_window = 0;
-    }
-    /* fetch any body bytes */
-    while (!stream_writing->fetching && stream_writing->send_message &&
-           stream_writing->flow_controlled_buffer.length < max_outgoing &&
-           stream_writing->stream_fetched <
-               stream_writing->send_message->length) {
-      if (grpc_byte_stream_next(exec_ctx, stream_writing->send_message,
-                                &stream_writing->fetching_slice, max_outgoing,
-                                &stream_writing->finished_fetch)) {
-        stream_writing->stream_fetched +=
-            GPR_SLICE_LENGTH(stream_writing->fetching_slice);
-        if (stream_writing->stream_fetched ==
-            stream_writing->send_message->length) {
-          stream_writing->send_message = NULL;
-        }
-        gpr_slice_buffer_add(&stream_writing->flow_controlled_buffer,
-                             stream_writing->fetching_slice);
-      } else {
-        stream_writing->fetching = 1;
-      }
-    }
-    /* send any body bytes */
-    if (stream_writing->flow_controlled_buffer.length > 0) {
-      if (max_outgoing > 0) {
-        uint32_t send_bytes = (uint32_t)GPR_MIN(
-            max_outgoing, stream_writing->flow_controlled_buffer.length);
-        int is_last_data_frame =
-            stream_writing->send_message == NULL &&
-            send_bytes == stream_writing->flow_controlled_buffer.length;
-        int is_last_frame = is_last_data_frame &&
-                            stream_writing->send_trailing_metadata != NULL &&
-                            grpc_metadata_batch_is_empty(
-                                stream_writing->send_trailing_metadata);
-        grpc_chttp2_encode_data(
-            stream_writing->id, &stream_writing->flow_controlled_buffer,
-            send_bytes, is_last_frame, &stream_writing->stats,
-            &transport_writing->outbuf);
-        if (is_first_data_frame) {
-          /* TODO(dgq): this is a hack. It'll be fix in a future refactoring */
-          stream_writing->stats.data_bytes -= 5; /* discount grpc framing */
-          is_first_data_frame = false;
-        }
-        GRPC_CHTTP2_FLOW_DEBIT_STREAM("write", transport_writing,
-                                      stream_writing, outgoing_window,
-                                      send_bytes);
-        GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("write", transport_writing,
-                                         outgoing_window, send_bytes);
-        if (is_last_frame) {
-          stream_writing->send_trailing_metadata = NULL;
-          stream_writing->sent_trailing_metadata = 1;
-        }
-        if (is_last_data_frame) {
-          GPR_ASSERT(stream_writing->send_message == NULL);
-          stream_writing->sent_message = 1;
-        }
-      } else if (transport_writing->outgoing_window == 0) {
-        grpc_chttp2_list_add_writing_stalled_by_transport(transport_writing,
-                                                          stream_writing);
-        grpc_chttp2_list_add_written_stream(transport_writing, stream_writing);
-      }
-    }
-    /* send trailing metadata if it's available and we're ready for it */
-    if (stream_writing->send_message == NULL &&
-        stream_writing->flow_controlled_buffer.length == 0 &&
-        stream_writing->send_trailing_metadata != NULL) {
-      if (grpc_metadata_batch_is_empty(
-              stream_writing->send_trailing_metadata)) {
-        grpc_chttp2_encode_data(
-            stream_writing->id, &stream_writing->flow_controlled_buffer, 0, 1,
-            &stream_writing->stats, &transport_writing->outbuf);
-      } else {
-        grpc_chttp2_encode_header(
-            &transport_writing->hpack_compressor, stream_writing->id,
-            stream_writing->send_trailing_metadata, 1,
-            transport_writing->max_frame_size, &stream_writing->stats,
-            &transport_writing->outbuf);
-      }
-      if (!transport_writing->is_client && !stream_writing->read_closed) {
-        gpr_slice_buffer_add(&transport_writing->outbuf,
-                             grpc_chttp2_rst_stream_create(
-                                 stream_writing->id, GRPC_CHTTP2_NO_ERROR,
-                                 &stream_writing->stats));
-      }
-      stream_writing->send_trailing_metadata = NULL;
-      stream_writing->sent_trailing_metadata = 1;
-    }
-    /* if there's more to write, then loop, otherwise prepare to finish the
-     * write */
-    if ((stream_writing->flow_controlled_buffer.length > 0 ||
-         (stream_writing->send_message && !stream_writing->fetching)) &&
-        stream_writing->outgoing_window > 0) {
-      if (transport_writing->outgoing_window > 0) {
-        grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
-      } else {
-        grpc_chttp2_list_add_writing_stalled_by_transport(transport_writing,
-                                                          stream_writing);
-        grpc_chttp2_list_add_written_stream(transport_writing, stream_writing);
-      }
-    } else {
-      grpc_chttp2_list_add_written_stream(transport_writing, stream_writing);
-    }
-  }
+  GPR_TIMER_END("grpc_chttp2_begin_write", 0);
 
-  GPR_TIMER_END("finalize_outbuf", 0);
+  return t->outbuf.count > 0;
 }
 
-void grpc_chttp2_cleanup_writing(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing) {
-  grpc_chttp2_stream_writing *stream_writing;
-  grpc_chttp2_stream_global *stream_global;
+void grpc_chttp2_end_write(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+                           grpc_error *error) {
+  GPR_TIMER_BEGIN("grpc_chttp2_end_write", 0);
+  grpc_chttp2_stream *s;
 
-  if (grpc_chttp2_list_flush_writing_stalled_by_transport(exec_ctx,
-                                                          transport_writing)) {
-    grpc_chttp2_initiate_write(exec_ctx, transport_global, false,
-                               "resume_stalled_stream");
-  }
-
-  while (grpc_chttp2_list_pop_written_stream(
-      transport_global, transport_writing, &stream_global, &stream_writing)) {
-    if (stream_writing->sent_initial_metadata) {
+  while (grpc_chttp2_list_pop_writing_stream(t, &s)) {
+    if (s->sent_initial_metadata) {
       grpc_chttp2_complete_closure_step(
-          exec_ctx, transport_global, stream_global,
-          &stream_global->send_initial_metadata_finished, GRPC_ERROR_NONE);
+          exec_ctx, t, s, &s->send_initial_metadata_finished,
+          GRPC_ERROR_REF(error), "send_initial_metadata_finished");
     }
-    grpc_transport_move_one_way_stats(&stream_writing->stats,
-                                      &stream_global->stats.outgoing);
-    if (stream_writing->sent_message) {
-      GPR_ASSERT(stream_writing->send_message == NULL);
-      grpc_chttp2_complete_closure_step(
-          exec_ctx, transport_global, stream_global,
-          &stream_global->send_message_finished, GRPC_ERROR_NONE);
-      stream_writing->sent_message = 0;
+    if (s->sending_bytes != 0) {
+      update_list(exec_ctx, t, s, s->sending_bytes, &s->on_write_finished_cbs,
+                  GRPC_ERROR_REF(error));
+      s->sending_bytes = 0;
     }
-    if (stream_writing->sent_trailing_metadata) {
+    if (s->sent_trailing_metadata) {
       grpc_chttp2_complete_closure_step(
-          exec_ctx, transport_global, stream_global,
-          &stream_global->send_trailing_metadata_finished, GRPC_ERROR_NONE);
-    }
-    if (stream_writing->sent_trailing_metadata) {
-      grpc_chttp2_mark_stream_closed(exec_ctx, transport_global, stream_global,
-                                     !transport_global->is_client, 1,
-                                     GRPC_ERROR_NONE);
+          exec_ctx, t, s, &s->send_trailing_metadata_finished,
+          GRPC_ERROR_REF(error), "send_trailing_metadata_finished");
+      grpc_chttp2_mark_stream_closed(exec_ctx, t, s, !t->is_client, 1,
+                                     GRPC_ERROR_REF(error));
     }
-    GRPC_CHTTP2_STREAM_UNREF(exec_ctx, stream_global, "chttp2_writing");
+    GRPC_CHTTP2_STREAM_UNREF(exec_ctx, s, "chttp2_writing:end");
   }
-  gpr_slice_buffer_reset_and_unref(&transport_writing->outbuf);
+  gpr_slice_buffer_reset_and_unref(&t->outbuf);
+  GRPC_ERROR_UNREF(error);
+  GPR_TIMER_END("grpc_chttp2_end_write", 0);
 }

src/core/lib/channel/channel_args.c

@@ -271,3 +271,21 @@ int grpc_channel_args_compare(const grpc_channel_args *a,
   }
   return 0;
 }
+
+int grpc_channel_arg_get_integer(grpc_arg *arg, grpc_integer_options options) {
+  if (arg->type != GRPC_ARG_INTEGER) {
+    gpr_log(GPR_ERROR, "%s ignored: it must be an integer", arg->key);
+    return options.default_value;
+  }
+  if (arg->value.integer < options.min_value) {
+    gpr_log(GPR_ERROR, "%s ignored: it must be >= %d", arg->key,
+            options.min_value);
+    return options.default_value;
+  }
+  if (arg->value.integer > options.max_value) {
+    gpr_log(GPR_ERROR, "%s ignored: it must be <= %d", arg->key,
+            options.max_value);
+    return options.default_value;
+  }
+  return arg->value.integer;
+}

src/core/lib/channel/channel_args.h

@@ -89,4 +89,12 @@ uint32_t grpc_channel_args_compression_algorithm_get_states(
 int grpc_channel_args_compare(const grpc_channel_args *a,
                               const grpc_channel_args *b);
 
+typedef struct grpc_integer_options {
+  int default_value;  // Return this if value is outside of expected bounds.
+  int min_value;
+  int max_value;
+} grpc_integer_options;
+/** Returns the value of \a arg, subject to the contraints in \a options. */
+int grpc_channel_arg_get_integer(grpc_arg *arg, grpc_integer_options options);
+
 #endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_ARGS_H */

src/core/lib/channel/channel_stack.c

@@ -32,6 +32,7 @@
  */
 
 #include "src/core/lib/channel/channel_stack.h"
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
 #include <stdlib.h>
@@ -270,21 +271,27 @@ grpc_call_stack *grpc_call_stack_from_top_element(grpc_call_element *elem) {
       sizeof(grpc_call_stack)));
 }
 
+static void destroy_op(grpc_exec_ctx *exec_ctx, void *op, grpc_error *error) {
+  gpr_free(op);
+}
+
 void grpc_call_element_send_cancel(grpc_exec_ctx *exec_ctx,
                                    grpc_call_element *cur_elem) {
-  grpc_transport_stream_op op;
-  memset(&op, 0, sizeof(op));
-  op.cancel_error = GRPC_ERROR_CANCELLED;
-  grpc_call_next_op(exec_ctx, cur_elem, &op);
+  grpc_transport_stream_op *op = gpr_malloc(sizeof(*op));
+  memset(op, 0, sizeof(*op));
+  op->cancel_error = GRPC_ERROR_CANCELLED;
+  op->on_complete = grpc_closure_create(destroy_op, op);
+  grpc_call_next_op(exec_ctx, cur_elem, op);
 }
 
 void grpc_call_element_send_cancel_with_message(grpc_exec_ctx *exec_ctx,
                                                 grpc_call_element *cur_elem,
                                                 grpc_status_code status,
                                                 gpr_slice *optional_message) {
-  grpc_transport_stream_op op;
-  memset(&op, 0, sizeof(op));
-  grpc_transport_stream_op_add_cancellation_with_message(&op, status,
+  grpc_transport_stream_op *op = gpr_malloc(sizeof(*op));
+  memset(op, 0, sizeof(*op));
+  op->on_complete = grpc_closure_create(destroy_op, op);
+  grpc_transport_stream_op_add_cancellation_with_message(op, status,
                                                          optional_message);
-  grpc_call_next_op(exec_ctx, cur_elem, &op);
+  grpc_call_next_op(exec_ctx, cur_elem, op);
 }

src/core/lib/channel/compress_filter.c

@@ -60,7 +60,7 @@ typedef struct call_data {
   /** If true, contents of \a compression_algorithm are authoritative */
   int has_compression_algorithm;
 
-  grpc_transport_stream_op send_op;
+  grpc_transport_stream_op *send_op;
   uint32_t send_length;
   uint32_t send_flags;
   gpr_slice incoming_slice;
@@ -199,11 +199,11 @@ static void finish_send_message(grpc_exec_ctx *exec_ctx,
 
   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;
+  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);
+  grpc_call_next_op(exec_ctx, elem, calld->send_op);
 }
 
 static void got_slice(grpc_exec_ctx *exec_ctx, void *elemp, grpc_error *error) {
@@ -220,7 +220,7 @@ static void got_slice(grpc_exec_ctx *exec_ctx, void *elemp, grpc_error *error) {
 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,
+  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);
@@ -243,7 +243,7 @@ static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
   }
   if (op->send_message != NULL && !skip_compression(elem) &&
       0 == (op->send_message->flags & GRPC_WRITE_NO_COMPRESS)) {
-    calld->send_op = *op;
+    calld->send_op = op;
     calld->send_length = op->send_message->length;
     calld->send_flags = op->send_message->flags;
     continue_send_message(exec_ctx, elem);

src/core/lib/channel/message_size_filter.c

@@ -0,0 +1,165 @@
+//
+// Copyright 2016, 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/lib/channel/message_size_filter.h"
+
+#include <limits.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+#include "src/core/lib/channel/channel_args.h"
+
+// The protobuf library will (by default) start warning at 100 megs.
+#define DEFAULT_MAX_MESSAGE_LENGTH (4 * 1024 * 1024)
+
+typedef struct call_data {
+  // Receive closures are chained: we inject this closure as the
+  // recv_message_ready up-call on transport_stream_op, and remember to
+  // call our next_recv_message_ready member after handling it.
+  grpc_closure recv_message_ready;
+  // Used by recv_message_ready.
+  grpc_byte_stream** recv_message;
+  // Original recv_message_ready callback, invoked after our own.
+  grpc_closure* next_recv_message_ready;
+} call_data;
+
+typedef struct channel_data {
+  size_t max_send_size;
+  size_t max_recv_size;
+} channel_data;
+
+// Callback invoked when we receive a message.  Here we check the max
+// receive message size.
+static void recv_message_ready(grpc_exec_ctx* exec_ctx, void* user_data,
+                               grpc_error* error) {
+  grpc_call_element* elem = user_data;
+  call_data* calld = elem->call_data;
+  channel_data* chand = elem->channel_data;
+  if (*calld->recv_message != NULL &&
+      (*calld->recv_message)->length > chand->max_recv_size) {
+    char* message_string;
+    gpr_asprintf(
+        &message_string, "Received message larger than max (%u vs. %lu)",
+        (*calld->recv_message)->length, (unsigned long)chand->max_recv_size);
+    gpr_slice message = gpr_slice_from_copied_string(message_string);
+    gpr_free(message_string);
+    grpc_call_element_send_cancel_with_message(
+        exec_ctx, elem, GRPC_STATUS_INVALID_ARGUMENT, &message);
+  }
+  // Invoke the next callback.
+  grpc_exec_ctx_sched(exec_ctx, calld->next_recv_message_ready, error, NULL);
+}
+
+// Start transport op.
+static void start_transport_stream_op(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;
+  // Check max send message size.
+  if (op->send_message != NULL &&
+      op->send_message->length > chand->max_send_size) {
+    char* message_string;
+    gpr_asprintf(&message_string, "Sent message larger than max (%u vs. %lu)",
+                 op->send_message->length, (unsigned long)chand->max_send_size);
+    gpr_slice message = gpr_slice_from_copied_string(message_string);
+    gpr_free(message_string);
+    grpc_call_element_send_cancel_with_message(
+        exec_ctx, elem, GRPC_STATUS_INVALID_ARGUMENT, &message);
+  }
+  // Inject callback for receiving a message.
+  if (op->recv_message_ready != NULL) {
+    calld->next_recv_message_ready = op->recv_message_ready;
+    calld->recv_message = op->recv_message;
+    op->recv_message_ready = &calld->recv_message_ready;
+  }
+  // Chain to the next filter.
+  grpc_call_next_op(exec_ctx, elem, op);
+}
+
+// Constructor for call_data.
+static grpc_error* init_call_elem(grpc_exec_ctx* exec_ctx,
+                                  grpc_call_element* elem,
+                                  grpc_call_element_args* args) {
+  call_data* calld = elem->call_data;
+  calld->next_recv_message_ready = NULL;
+  grpc_closure_init(&calld->recv_message_ready, recv_message_ready, elem);
+  return GRPC_ERROR_NONE;
+}
+
+// Destructor for call_data.
+static void destroy_call_elem(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
+                              const grpc_call_final_info* final_info,
+                              void* ignored) {}
+
+// Constructor for channel_data.
+static void init_channel_elem(grpc_exec_ctx* exec_ctx,
+                              grpc_channel_element* elem,
+                              grpc_channel_element_args* args) {
+  GPR_ASSERT(!args->is_last);
+  channel_data* chand = elem->channel_data;
+  memset(chand, 0, sizeof(*chand));
+  chand->max_send_size = DEFAULT_MAX_MESSAGE_LENGTH;
+  chand->max_recv_size = DEFAULT_MAX_MESSAGE_LENGTH;
+  const grpc_integer_options options = {DEFAULT_MAX_MESSAGE_LENGTH, 0, INT_MAX};
+  for (size_t i = 0; i < args->channel_args->num_args; ++i) {
+    if (strcmp(args->channel_args->args[i].key,
+               GRPC_ARG_MAX_SEND_MESSAGE_LENGTH) == 0) {
+      chand->max_send_size = (size_t)grpc_channel_arg_get_integer(
+          &args->channel_args->args[i], options);
+    }
+    if (strcmp(args->channel_args->args[i].key,
+               GRPC_ARG_MAX_RECEIVE_MESSAGE_LENGTH) == 0) {
+      chand->max_recv_size = (size_t)grpc_channel_arg_get_integer(
+          &args->channel_args->args[i], options);
+    }
+  }
+}
+
+// Destructor for channel_data.
+static void destroy_channel_elem(grpc_exec_ctx* exec_ctx,
+                                 grpc_channel_element* elem) {}
+
+const grpc_channel_filter grpc_message_size_filter = {
+    start_transport_stream_op,
+    grpc_channel_next_op,
+    sizeof(call_data),
+    init_call_elem,
+    grpc_call_stack_ignore_set_pollset_or_pollset_set,
+    destroy_call_elem,
+    sizeof(channel_data),
+    init_channel_elem,
+    destroy_channel_elem,
+    grpc_call_next_get_peer,
+    "message_size"};

src/core/lib/channel/message_size_filter.h

@@ -0,0 +1,39 @@
+//
+// Copyright 2016, 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_CORE_LIB_CHANNEL_MESSAGE_SIZE_FILTER_H
+#define GRPC_CORE_LIB_CHANNEL_MESSAGE_SIZE_FILTER_H
+
+#include "src/core/lib/channel/channel_stack.h"
+
+extern const grpc_channel_filter grpc_message_size_filter;
+
+#endif /* GRPC_CORE_LIB_CHANNEL_MESSAGE_SIZE_FILTER_H */

src/core/lib/iomgr/closure.c

@@ -35,19 +35,25 @@
 
 #include <grpc/support/alloc.h>
 
+#include "src/core/lib/profiling/timers.h"
+
 void grpc_closure_init(grpc_closure *closure, grpc_iomgr_cb_func cb,
                        void *cb_arg) {
   closure->cb = cb;
   closure->cb_arg = cb_arg;
 }
 
+void grpc_closure_list_init(grpc_closure_list *closure_list) {
+  closure_list->head = closure_list->tail = NULL;
+}
+
 void grpc_closure_list_append(grpc_closure_list *closure_list,
                               grpc_closure *closure, grpc_error *error) {
   if (closure == NULL) {
     GRPC_ERROR_UNREF(error);
     return;
   }
-  closure->error = error;
+  closure->error_data.error = error;
   closure->next_data.next = NULL;
   if (closure_list->head == NULL) {
     closure_list->head = closure;
@@ -60,8 +66,8 @@ void grpc_closure_list_append(grpc_closure_list *closure_list,
 void grpc_closure_list_fail_all(grpc_closure_list *list,
                                 grpc_error *forced_failure) {
   for (grpc_closure *c = list->head; c != NULL; c = c->next_data.next) {
-    if (c->error == GRPC_ERROR_NONE) {
-      c->error = GRPC_ERROR_REF(forced_failure);
+    if (c->error_data.error == GRPC_ERROR_NONE) {
+      c->error_data.error = GRPC_ERROR_REF(forced_failure);
     }
   }
   GRPC_ERROR_UNREF(forced_failure);
@@ -106,3 +112,11 @@ grpc_closure *grpc_closure_create(grpc_iomgr_cb_func cb, void *cb_arg) {
   grpc_closure_init(&wc->wrapper, closure_wrapper, wc);
   return &wc->wrapper;
 }
+
+void grpc_closure_run(grpc_exec_ctx *exec_ctx, grpc_closure *c,
+                      grpc_error *error) {
+  GPR_TIMER_BEGIN("grpc_closure_run", 0);
+  c->cb(exec_ctx, c->cb_arg, error);
+  GRPC_ERROR_UNREF(error);
+  GPR_TIMER_END("grpc_closure_run", 0);
+}

src/core/lib/iomgr/closure.h

@@ -37,6 +37,7 @@
 #include <grpc/support/port_platform.h>
 #include <stdbool.h>
 #include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/support/mpscq.h"
 
 struct grpc_closure;
 typedef struct grpc_closure grpc_closure;
@@ -60,6 +61,14 @@ typedef void (*grpc_iomgr_cb_func)(grpc_exec_ctx *exec_ctx, void *arg,
 
 /** A closure over a grpc_iomgr_cb_func. */
 struct grpc_closure {
+  /** Once queued, next indicates the next queued closure; before then, scratch
+   *  space */
+  union {
+    grpc_closure *next;
+    gpr_mpscq_node atm_next;
+    uintptr_t scratch;
+  } next_data;
+
   /** Bound callback. */
   grpc_iomgr_cb_func cb;
 
@@ -67,14 +76,10 @@ struct grpc_closure {
   void *cb_arg;
 
   /** Once queued, the result of the closure. Before then: scratch space */
-  grpc_error *error;
-
-  /** Once queued, next indicates the next queued closure; before then, scratch
-   *  space */
   union {
-    grpc_closure *next;
+    grpc_error *error;
     uintptr_t scratch;
-  } next_data;
+  } error_data;
 };
 
 /** Initializes \a closure with \a cb and \a cb_arg. */
@@ -87,6 +92,8 @@ grpc_closure *grpc_closure_create(grpc_iomgr_cb_func cb, void *cb_arg);
 #define GRPC_CLOSURE_LIST_INIT \
   { NULL, NULL }
 
+void grpc_closure_list_init(grpc_closure_list *list);
+
 /** add \a closure to the end of \a list
     and set \a closure's result to \a error */
 void grpc_closure_list_append(grpc_closure_list *list, grpc_closure *closure,
@@ -102,4 +109,10 @@ void grpc_closure_list_move(grpc_closure_list *src, grpc_closure_list *dst);
 /** return whether \a list is empty. */
 bool grpc_closure_list_empty(grpc_closure_list list);
 
+/** Run a closure directly. Caller ensures that no locks are being held above.
+ *  Note that calling this at the end of a closure callback function itself is
+ *  by definition safe. */
+void grpc_closure_run(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
+                      grpc_error *error);
+
 #endif /* GRPC_CORE_LIB_IOMGR_CLOSURE_H */

src/core/lib/iomgr/combiner.c

@@ -0,0 +1,324 @@
+/*
+ *
+ * Copyright 2016, 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/lib/iomgr/combiner.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+
+#include "src/core/lib/iomgr/workqueue.h"
+#include "src/core/lib/profiling/timers.h"
+
+int grpc_combiner_trace = 0;
+
+#define GRPC_COMBINER_TRACE(fn) \
+  do {                          \
+    if (grpc_combiner_trace) {  \
+      fn;                       \
+    }                           \
+  } while (0)
+
+struct grpc_combiner {
+  grpc_combiner *next_combiner_on_this_exec_ctx;
+  grpc_workqueue *optional_workqueue;
+  gpr_mpscq queue;
+  // state is:
+  // lower bit - zero if orphaned
+  // other bits - number of items queued on the lock
+  gpr_atm state;
+  // number of elements in the list that are covered by a poller: if >0, we can
+  // offload safely
+  gpr_atm covered_by_poller;
+  bool time_to_execute_final_list;
+  bool final_list_covered_by_poller;
+  grpc_closure_list final_list;
+  grpc_closure offload;
+};
+
+static void offload(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error);
+
+typedef struct {
+  grpc_error *error;
+  bool covered_by_poller;
+} error_data;
+
+static uintptr_t pack_error_data(error_data d) {
+  return ((uintptr_t)d.error) | (d.covered_by_poller ? 1 : 0);
+}
+
+static error_data unpack_error_data(uintptr_t p) {
+  return (error_data){(grpc_error *)(p & ~(uintptr_t)1), p & 1};
+}
+
+static bool is_covered_by_poller(grpc_combiner *lock) {
+  return lock->final_list_covered_by_poller ||
+         gpr_atm_acq_load(&lock->covered_by_poller) > 0;
+}
+
+grpc_combiner *grpc_combiner_create(grpc_workqueue *optional_workqueue) {
+  grpc_combiner *lock = gpr_malloc(sizeof(*lock));
+  lock->next_combiner_on_this_exec_ctx = NULL;
+  lock->time_to_execute_final_list = false;
+  lock->optional_workqueue = optional_workqueue;
+  lock->final_list_covered_by_poller = false;
+  gpr_atm_no_barrier_store(&lock->state, 1);
+  gpr_atm_no_barrier_store(&lock->covered_by_poller, 0);
+  gpr_mpscq_init(&lock->queue);
+  grpc_closure_list_init(&lock->final_list);
+  grpc_closure_init(&lock->offload, offload, lock);
+  GRPC_COMBINER_TRACE(gpr_log(GPR_DEBUG, "C:%p create", lock));
+  return lock;
+}
+
+static void really_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
+  GRPC_COMBINER_TRACE(gpr_log(GPR_DEBUG, "C:%p really_destroy", lock));
+  GPR_ASSERT(gpr_atm_no_barrier_load(&lock->state) == 0);
+  gpr_mpscq_destroy(&lock->queue);
+  GRPC_WORKQUEUE_UNREF(exec_ctx, lock->optional_workqueue, "combiner");
+  gpr_free(lock);
+}
+
+void grpc_combiner_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
+  gpr_atm old_state = gpr_atm_full_fetch_add(&lock->state, -1);
+  GRPC_COMBINER_TRACE(gpr_log(
+      GPR_DEBUG, "C:%p really_destroy old_state=%" PRIdPTR, lock, old_state));
+  if (old_state == 1) {
+    really_destroy(exec_ctx, lock);
+  }
+}
+
+static void push_last_on_exec_ctx(grpc_exec_ctx *exec_ctx,
+                                  grpc_combiner *lock) {
+  lock->next_combiner_on_this_exec_ctx = NULL;
+  if (exec_ctx->active_combiner == NULL) {
+    exec_ctx->active_combiner = exec_ctx->last_combiner = lock;
+  } else {
+    exec_ctx->last_combiner->next_combiner_on_this_exec_ctx = lock;
+    exec_ctx->last_combiner = lock;
+  }
+}
+
+static void push_first_on_exec_ctx(grpc_exec_ctx *exec_ctx,
+                                   grpc_combiner *lock) {
+  lock->next_combiner_on_this_exec_ctx = exec_ctx->active_combiner;
+  exec_ctx->active_combiner = lock;
+  if (lock->next_combiner_on_this_exec_ctx == NULL) {
+    exec_ctx->last_combiner = lock;
+  }
+}
+
+void grpc_combiner_execute(grpc_exec_ctx *exec_ctx, grpc_combiner *lock,
+                           grpc_closure *cl, grpc_error *error,
+                           bool covered_by_poller) {
+  GPR_TIMER_BEGIN("combiner.execute", 0);
+  gpr_atm last = gpr_atm_full_fetch_add(&lock->state, 2);
+  GRPC_COMBINER_TRACE(gpr_log(
+      GPR_DEBUG, "C:%p grpc_combiner_execute c=%p cov=%d last=%" PRIdPTR, lock,
+      cl, covered_by_poller, last));
+  GPR_ASSERT(last & 1);  // ensure lock has not been destroyed
+  cl->error_data.scratch =
+      pack_error_data((error_data){error, covered_by_poller});
+  if (covered_by_poller) {
+    gpr_atm_no_barrier_fetch_add(&lock->covered_by_poller, 1);
+  }
+  gpr_mpscq_push(&lock->queue, &cl->next_data.atm_next);
+  if (last == 1) {
+    // code will be written when the exec_ctx calls
+    // grpc_combiner_continue_exec_ctx
+    push_last_on_exec_ctx(exec_ctx, lock);
+  }
+  GPR_TIMER_END("combiner.execute", 0);
+}
+
+static void move_next(grpc_exec_ctx *exec_ctx) {
+  exec_ctx->active_combiner =
+      exec_ctx->active_combiner->next_combiner_on_this_exec_ctx;
+  if (exec_ctx->active_combiner == NULL) {
+    exec_ctx->last_combiner = NULL;
+  }
+}
+
+static void offload(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
+  grpc_combiner *lock = arg;
+  push_last_on_exec_ctx(exec_ctx, lock);
+}
+
+static void queue_offload(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
+  move_next(exec_ctx);
+  GRPC_COMBINER_TRACE(gpr_log(GPR_DEBUG, "C:%p queue_offload --> %p", lock,
+                              lock->optional_workqueue));
+  grpc_workqueue_enqueue(exec_ctx, lock->optional_workqueue, &lock->offload,
+                         GRPC_ERROR_NONE);
+}
+
+bool grpc_combiner_continue_exec_ctx(grpc_exec_ctx *exec_ctx) {
+  GPR_TIMER_BEGIN("combiner.continue_exec_ctx", 0);
+  grpc_combiner *lock = exec_ctx->active_combiner;
+  if (lock == NULL) {
+    GPR_TIMER_END("combiner.continue_exec_ctx", 0);
+    return false;
+  }
+
+  GRPC_COMBINER_TRACE(
+      gpr_log(GPR_DEBUG,
+              "C:%p grpc_combiner_continue_exec_ctx workqueue=%p "
+              "is_covered_by_poller=%d exec_ctx_ready_to_finish=%d "
+              "time_to_execute_final_list=%d",
+              lock, lock->optional_workqueue, is_covered_by_poller(lock),
+              grpc_exec_ctx_ready_to_finish(exec_ctx),
+              lock->time_to_execute_final_list));
+
+  if (lock->optional_workqueue != NULL && is_covered_by_poller(lock) &&
+      grpc_exec_ctx_ready_to_finish(exec_ctx)) {
+    GPR_TIMER_MARK("offload_from_finished_exec_ctx", 0);
+    // this execution context wants to move on, and we have a workqueue (and
+    // so can help the execution context out): schedule remaining work to be
+    // picked up on the workqueue
+    queue_offload(exec_ctx, lock);
+    GPR_TIMER_END("combiner.continue_exec_ctx", 0);
+    return true;
+  }
+
+  if (!lock->time_to_execute_final_list ||
+      // peek to see if something new has shown up, and execute that with
+      // priority
+      (gpr_atm_acq_load(&lock->state) >> 1) > 1) {
+    gpr_mpscq_node *n = gpr_mpscq_pop(&lock->queue);
+    GRPC_COMBINER_TRACE(
+        gpr_log(GPR_DEBUG, "C:%p maybe_finish_one n=%p", lock, n));
+    if (n == NULL) {
+      // queue is in an inconsistant state: use this as a cue that we should
+      // go off and do something else for a while (and come back later)
+      GPR_TIMER_MARK("delay_busy", 0);
+      if (lock->optional_workqueue != NULL && is_covered_by_poller(lock)) {
+        queue_offload(exec_ctx, lock);
+      }
+      GPR_TIMER_END("combiner.continue_exec_ctx", 0);
+      return true;
+    }
+    GPR_TIMER_BEGIN("combiner.exec1", 0);
+    grpc_closure *cl = (grpc_closure *)n;
+    error_data err = unpack_error_data(cl->error_data.scratch);
+    cl->cb(exec_ctx, cl->cb_arg, err.error);
+    if (err.covered_by_poller) {
+      gpr_atm_no_barrier_fetch_add(&lock->covered_by_poller, -1);
+    }
+    GRPC_ERROR_UNREF(err.error);
+    GPR_TIMER_END("combiner.exec1", 0);
+  } else {
+    grpc_closure *c = lock->final_list.head;
+    GPR_ASSERT(c != NULL);
+    grpc_closure_list_init(&lock->final_list);
+    lock->final_list_covered_by_poller = false;
+    int loops = 0;
+    while (c != NULL) {
+      GPR_TIMER_BEGIN("combiner.exec_1final", 0);
+      GRPC_COMBINER_TRACE(
+          gpr_log(GPR_DEBUG, "C:%p execute_final[%d] c=%p", lock, loops, c));
+      grpc_closure *next = c->next_data.next;
+      grpc_error *error = c->error_data.error;
+      c->cb(exec_ctx, c->cb_arg, error);
+      GRPC_ERROR_UNREF(error);
+      c = next;
+      GPR_TIMER_END("combiner.exec_1final", 0);
+    }
+  }
+
+  GPR_TIMER_MARK("unref", 0);
+  move_next(exec_ctx);
+  lock->time_to_execute_final_list = false;
+  gpr_atm old_state = gpr_atm_full_fetch_add(&lock->state, -2);
+  GRPC_COMBINER_TRACE(
+      gpr_log(GPR_DEBUG, "C:%p finish old_state=%" PRIdPTR, lock, old_state));
+  switch (old_state) {
+    default:
+      // we have multiple queued work items: just continue executing them
+      break;
+    case 5:  // we're down to one queued item: if it's the final list we
+    case 4:  // should do that
+      if (!grpc_closure_list_empty(lock->final_list)) {
+        lock->time_to_execute_final_list = true;
+      }
+      break;
+    case 3:  // had one count, one unorphaned --> unlocked unorphaned
+      GPR_TIMER_END("combiner.continue_exec_ctx", 0);
+      return true;
+    case 2:  // and one count, one orphaned --> unlocked and orphaned
+      really_destroy(exec_ctx, lock);
+      GPR_TIMER_END("combiner.continue_exec_ctx", 0);
+      return true;
+    case 1:
+    case 0:
+      // these values are illegal - representing an already unlocked or
+      // deleted lock
+      GPR_TIMER_END("combiner.continue_exec_ctx", 0);
+      GPR_UNREACHABLE_CODE(return true);
+  }
+  push_first_on_exec_ctx(exec_ctx, lock);
+  GPR_TIMER_END("combiner.continue_exec_ctx", 0);
+  return true;
+}
+
+static void enqueue_finally(grpc_exec_ctx *exec_ctx, void *closure,
+                            grpc_error *error) {
+  grpc_combiner_execute_finally(exec_ctx, exec_ctx->active_combiner, closure,
+                                GRPC_ERROR_REF(error), false);
+}
+
+void grpc_combiner_execute_finally(grpc_exec_ctx *exec_ctx, grpc_combiner *lock,
+                                   grpc_closure *closure, grpc_error *error,
+                                   bool covered_by_poller) {
+  GRPC_COMBINER_TRACE(gpr_log(
+      GPR_DEBUG, "C:%p grpc_combiner_execute_finally c=%p; ac=%p; cov=%d", lock,
+      closure, exec_ctx->active_combiner, covered_by_poller));
+  GPR_TIMER_BEGIN("combiner.execute_finally", 0);
+  if (exec_ctx->active_combiner != lock) {
+    GPR_TIMER_MARK("slowpath", 0);
+    grpc_combiner_execute(exec_ctx, lock,
+                          grpc_closure_create(enqueue_finally, closure), error,
+                          false);
+    GPR_TIMER_END("combiner.execute_finally", 0);
+    return;
+  }
+
+  if (grpc_closure_list_empty(lock->final_list)) {
+    gpr_atm_full_fetch_add(&lock->state, 2);
+  }
+  if (covered_by_poller) {
+    lock->final_list_covered_by_poller = true;
+  }
+  grpc_closure_list_append(&lock->final_list, closure, error);
+  GPR_TIMER_END("combiner.execute_finally", 0);
+}

src/core/lib/iomgr/combiner.h

@@ -0,0 +1,66 @@
+/*
+ *
+ * Copyright 2016, 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_CORE_LIB_IOMGR_COMBINER_H
+#define GRPC_CORE_LIB_IOMGR_COMBINER_H
+
+#include <stddef.h>
+
+#include <grpc/support/atm.h>
+#include "src/core/lib/iomgr/exec_ctx.h"
+#include "src/core/lib/support/mpscq.h"
+
+// Provides serialized access to some resource.
+// Each action queued on a combiner is executed serially in a borrowed thread.
+// The actual thread executing actions may change over time (but there will only
+// every be one at a time).
+
+// Initialize the lock, with an optional workqueue to shift load to when
+// necessary
+grpc_combiner *grpc_combiner_create(grpc_workqueue *optional_workqueue);
+// Destroy the lock
+void grpc_combiner_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock);
+// Execute \a action within the lock.
+void grpc_combiner_execute(grpc_exec_ctx *exec_ctx, grpc_combiner *lock,
+                           grpc_closure *closure, grpc_error *error,
+                           bool covered_by_poller);
+// Execute \a action within the lock just prior to unlocking.
+void grpc_combiner_execute_finally(grpc_exec_ctx *exec_ctx, grpc_combiner *lock,
+                                   grpc_closure *closure, grpc_error *error,
+                                   bool covered_by_poller);
+
+bool grpc_combiner_continue_exec_ctx(grpc_exec_ctx *exec_ctx);
+
+extern int grpc_combiner_trace;
+
+#endif /* GRPC_CORE_LIB_IOMGR_COMBINER_H */

src/core/lib/iomgr/error.c

@@ -265,7 +265,7 @@ static grpc_error *copy_error_and_unref(grpc_error *in) {
   } else {
     out = gpr_malloc(sizeof(*out));
 #ifdef GRPC_ERROR_REFCOUNT_DEBUG
-    gpr_log(GPR_DEBUG, "%p create copying", out);
+    gpr_log(GPR_DEBUG, "%p create copying %p", out, in);
 #endif
     out->ints = gpr_avl_ref(in->ints);
     out->strs = gpr_avl_ref(in->strs);
@@ -332,7 +332,7 @@ grpc_error *grpc_error_add_child(grpc_error *src, grpc_error *child) {
   return new;
 }
 
-static const char *no_error_string = "null";
+static const char *no_error_string = "\"No Error\"";
 static const char *oom_error_string = "\"Out of memory\"";
 static const char *cancelled_error_string = "\"Cancelled\"";
 

src/core/lib/iomgr/error.h

@@ -123,9 +123,13 @@ typedef enum {
   GRPC_ERROR_TIME_CREATED,
 } grpc_error_times;
 
+/// The following "special" errors can be propagated without allocating memory.
+/// They are always even so that other code (particularly combiner locks) can
+/// safely use the lower bit for themselves.
+
 #define GRPC_ERROR_NONE ((grpc_error *)NULL)
-#define GRPC_ERROR_OOM ((grpc_error *)1)
-#define GRPC_ERROR_CANCELLED ((grpc_error *)2)
+#define GRPC_ERROR_OOM ((grpc_error *)2)
+#define GRPC_ERROR_CANCELLED ((grpc_error *)4)
 
 const char *grpc_error_string(grpc_error *error);
 void grpc_error_free_string(const char *str);

src/core/lib/iomgr/ev_epoll_linux.c

@@ -152,14 +152,13 @@ static void fd_global_shutdown(void);
  * Polling island Declarations
  */
 
-//#define GRPC_PI_REF_COUNT_DEBUG
-#ifdef GRPC_PI_REF_COUNT_DEBUG
+#ifdef GRPC_WORKQUEUE_REFCOUNT_DEBUG
 
 #define PI_ADD_REF(p, r) pi_add_ref_dbg((p), (r), __FILE__, __LINE__)
 #define PI_UNREF(exec_ctx, p, r) \
   pi_unref_dbg((exec_ctx), (p), (r), __FILE__, __LINE__)
 
-#else /* defined(GRPC_PI_REF_COUNT_DEBUG) */
+#else /* defined(GRPC_WORKQUEUE_REFCOUNT_DEBUG) */
 
 #define PI_ADD_REF(p, r) pi_add_ref((p))
 #define PI_UNREF(exec_ctx, p, r) pi_unref((exec_ctx), (p))
@@ -185,8 +184,11 @@ typedef struct polling_island {
    * (except mu and ref_count) are invalid and must be ignored. */
   gpr_atm merged_to;
 
-  /* The workqueue associated with this polling island */
-  grpc_workqueue *workqueue;
+  gpr_atm poller_count;
+  gpr_mu workqueue_read_mu;
+  gpr_mpscq workqueue_items;
+  gpr_atm workqueue_item_count;
+  grpc_wakeup_fd workqueue_wakeup_fd;
 
   /* The fd of the underlying epoll set */
   int epoll_fd;
@@ -275,6 +277,8 @@ static bool append_error(grpc_error **composite, grpc_error *error,
    threads that woke up MUST NOT call grpc_wakeup_fd_consume_wakeup() */
 static grpc_wakeup_fd polling_island_wakeup_fd;
 
+static __thread polling_island *g_current_thread_polling_island;
+
 /* Forward declaration */
 static void polling_island_delete(grpc_exec_ctx *exec_ctx, polling_island *pi);
 
@@ -289,12 +293,12 @@ static void polling_island_delete(grpc_exec_ctx *exec_ctx, polling_island *pi);
 gpr_atm g_epoll_sync;
 #endif /* defined(GRPC_TSAN) */
 
-#ifdef GRPC_PI_REF_COUNT_DEBUG
 static void pi_add_ref(polling_island *pi);
 static void pi_unref(grpc_exec_ctx *exec_ctx, polling_island *pi);
 
-static void pi_add_ref_dbg(polling_island *pi, char *reason, char *file,
-                           int line) {
+#ifdef GRPC_WORKQUEUE_REFCOUNT_DEBUG
+static void pi_add_ref_dbg(polling_island *pi, const char *reason,
+                           const char *file, int line) {
   long old_cnt = gpr_atm_acq_load(&pi->ref_count);
   pi_add_ref(pi);
   gpr_log(GPR_DEBUG, "Add ref pi: %p, old: %ld -> new:%ld (%s) - (%s, %d)",
@@ -302,12 +306,42 @@ static void pi_add_ref_dbg(polling_island *pi, char *reason, char *file,
 }
 
 static void pi_unref_dbg(grpc_exec_ctx *exec_ctx, polling_island *pi,
-                         char *reason, char *file, int line) {
+                         const char *reason, const char *file, int line) {
   long old_cnt = gpr_atm_acq_load(&pi->ref_count);
   pi_unref(exec_ctx, pi);
   gpr_log(GPR_DEBUG, "Unref pi: %p, old:%ld -> new:%ld (%s) - (%s, %d)",
           (void *)pi, old_cnt, (old_cnt - 1), reason, file, line);
 }
+
+static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue,
+                                     const char *file, int line,
+                                     const char *reason) {
+  if (workqueue != NULL) {
+    pi_add_ref_dbg((polling_island *)workqueue, reason, file, line);
+  }
+  return workqueue;
+}
+
+static void workqueue_unref(grpc_exec_ctx *exec_ctx, grpc_workqueue *workqueue,
+                            const char *file, int line, const char *reason) {
+  if (workqueue != NULL) {
+    pi_unref_dbg(exec_ctx, (polling_island *)workqueue, reason, file, line);
+  }
+}
+#else
+static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue) {
+  if (workqueue != NULL) {
+    pi_add_ref((polling_island *)workqueue);
+  }
+  return workqueue;
+}
+
+static void workqueue_unref(grpc_exec_ctx *exec_ctx,
+                            grpc_workqueue *workqueue) {
+  if (workqueue != NULL) {
+    pi_unref(exec_ctx, (polling_island *)workqueue);
+  }
+}
 #endif
 
 static void pi_add_ref(polling_island *pi) {
@@ -315,10 +349,7 @@ static void pi_add_ref(polling_island *pi) {
 }
 
 static void pi_unref(grpc_exec_ctx *exec_ctx, polling_island *pi) {
-  /* If ref count went to one, we're back to just the workqueue owning a ref.
-     Unref the workqueue to break the loop.
-
-     If ref count went to zero, delete the polling island.
+  /* If ref count went to zero, delete the polling island.
      Note that this deletion not be done under a lock. Once the ref count goes
      to zero, we are guaranteed that no one else holds a reference to the
      polling island (and that there is no racing pi_add_ref() call either).
@@ -326,20 +357,12 @@ static void pi_unref(grpc_exec_ctx *exec_ctx, polling_island *pi) {
      Also, if we are deleting the polling island and the merged_to field is
      non-empty, we should remove a ref to the merged_to polling island
    */
-  switch (gpr_atm_full_fetch_add(&pi->ref_count, -1)) {
-    case 2: /* last external ref: the only one now owned is by the workqueue */
-      GRPC_WORKQUEUE_UNREF(exec_ctx, pi->workqueue, "polling_island");
-      break;
-    case 1: {
-      polling_island *next = (polling_island *)gpr_atm_acq_load(&pi->merged_to);
-      polling_island_delete(exec_ctx, pi);
-      if (next != NULL) {
-        PI_UNREF(exec_ctx, next, "pi_delete"); /* Recursive call */
-      }
-      break;
+  if (1 == gpr_atm_full_fetch_add(&pi->ref_count, -1)) {
+    polling_island *next = (polling_island *)gpr_atm_acq_load(&pi->merged_to);
+    polling_island_delete(exec_ctx, pi);
+    if (next != NULL) {
+      PI_UNREF(exec_ctx, next, "pi_delete"); /* Recursive call */
     }
-    case 0:
-      GPR_UNREACHABLE_CODE(return );
   }
 }
 
@@ -488,11 +511,20 @@ static polling_island *polling_island_create(grpc_exec_ctx *exec_ctx,
   pi->fd_capacity = 0;
   pi->fds = NULL;
   pi->epoll_fd = -1;
-  pi->workqueue = NULL;
+
+  gpr_mu_init(&pi->workqueue_read_mu);
+  gpr_mpscq_init(&pi->workqueue_items);
+  gpr_atm_rel_store(&pi->workqueue_item_count, 0);
 
   gpr_atm_rel_store(&pi->ref_count, 0);
+  gpr_atm_rel_store(&pi->poller_count, 0);
   gpr_atm_rel_store(&pi->merged_to, (gpr_atm)NULL);
 
+  if (!append_error(error, grpc_wakeup_fd_init(&pi->workqueue_wakeup_fd),
+                    err_desc)) {
+    goto done;
+  }
+
   pi->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 
   if (pi->epoll_fd < 0) {
@@ -501,26 +533,14 @@ static polling_island *polling_island_create(grpc_exec_ctx *exec_ctx,
   }
 
   polling_island_add_wakeup_fd_locked(pi, &grpc_global_wakeup_fd, error);
+  polling_island_add_wakeup_fd_locked(pi, &pi->workqueue_wakeup_fd, error);
 
   if (initial_fd != NULL) {
     polling_island_add_fds_locked(pi, &initial_fd, 1, true, error);
   }
 
-  if (append_error(error, grpc_workqueue_create(exec_ctx, &pi->workqueue),
-                   err_desc) &&
-      *error == GRPC_ERROR_NONE) {
-    polling_island_add_fds_locked(pi, &pi->workqueue->wakeup_read_fd, 1, true,
-                                  error);
-    GPR_ASSERT(pi->workqueue->wakeup_read_fd->polling_island == NULL);
-    pi->workqueue->wakeup_read_fd->polling_island = pi;
-    PI_ADD_REF(pi, "fd");
-  }
-
 done:
   if (*error != GRPC_ERROR_NONE) {
-    if (pi->workqueue != NULL) {
-      GRPC_WORKQUEUE_UNREF(exec_ctx, pi->workqueue, "polling_island");
-    }
     polling_island_delete(exec_ctx, pi);
     pi = NULL;
   }
@@ -533,7 +553,11 @@ static void polling_island_delete(grpc_exec_ctx *exec_ctx, polling_island *pi) {
   if (pi->epoll_fd >= 0) {
     close(pi->epoll_fd);
   }
+  GPR_ASSERT(gpr_atm_no_barrier_load(&pi->workqueue_item_count) == 0);
+  gpr_mu_destroy(&pi->workqueue_read_mu);
+  gpr_mpscq_destroy(&pi->workqueue_items);
   gpr_mu_destroy(&pi->mu);
+  grpc_wakeup_fd_destroy(&pi->workqueue_wakeup_fd);
   gpr_free(pi->fds);
   gpr_free(pi);
 }
@@ -678,6 +702,40 @@ static void polling_island_unlock_pair(polling_island *p, polling_island *q) {
   }
 }
 
+static void workqueue_maybe_wakeup(polling_island *pi) {
+  bool force_wakeup = false;
+  bool is_current_poller = (g_current_thread_polling_island == pi);
+  gpr_atm min_current_pollers_for_wakeup = is_current_poller ? 1 : 0;
+  gpr_atm current_pollers = gpr_atm_no_barrier_load(&pi->poller_count);
+  if (force_wakeup || current_pollers > min_current_pollers_for_wakeup) {
+    GRPC_LOG_IF_ERROR("workqueue_wakeup_fd",
+                      grpc_wakeup_fd_wakeup(&pi->workqueue_wakeup_fd));
+  }
+}
+
+static void workqueue_move_items_to_parent(polling_island *q) {
+  polling_island *p = (polling_island *)gpr_atm_no_barrier_load(&q->merged_to);
+  if (p == NULL) {
+    return;
+  }
+  gpr_mu_lock(&q->workqueue_read_mu);
+  int num_added = 0;
+  while (gpr_atm_no_barrier_load(&q->workqueue_item_count) > 0) {
+    gpr_mpscq_node *n = gpr_mpscq_pop(&q->workqueue_items);
+    if (n != NULL) {
+      gpr_atm_no_barrier_fetch_add(&q->workqueue_item_count, -1);
+      gpr_atm_no_barrier_fetch_add(&p->workqueue_item_count, 1);
+      gpr_mpscq_push(&p->workqueue_items, n);
+      num_added++;
+    }
+  }
+  gpr_mu_unlock(&q->workqueue_read_mu);
+  if (num_added > 0) {
+    workqueue_maybe_wakeup(p);
+  }
+  workqueue_move_items_to_parent(p);
+}
+
 static polling_island *polling_island_merge(polling_island *p,
                                             polling_island *q,
                                             grpc_error **error) {
@@ -702,6 +760,8 @@ static polling_island *polling_island_merge(polling_island *p,
     /* Add the 'merged_to' link from p --> q */
     gpr_atm_rel_store(&p->merged_to, (gpr_atm)q);
     PI_ADD_REF(q, "pi_merge"); /* To account for the new incoming ref from p */
+
+    workqueue_move_items_to_parent(q);
   }
   /* else if p == q, nothing needs to be done */
 
@@ -712,6 +772,26 @@ static polling_island *polling_island_merge(polling_island *p,
   return q;
 }
 
+static void workqueue_enqueue(grpc_exec_ctx *exec_ctx,
+                              grpc_workqueue *workqueue, grpc_closure *closure,
+                              grpc_error *error) {
+  GPR_TIMER_BEGIN("workqueue.enqueue", 0);
+  /* take a ref to the workqueue: otherwise it can happen that whatever events
+   * this kicks off ends up destroying the workqueue before this function
+   * completes */
+  GRPC_WORKQUEUE_REF(workqueue, "enqueue");
+  polling_island *pi = (polling_island *)workqueue;
+  gpr_atm last = gpr_atm_no_barrier_fetch_add(&pi->workqueue_item_count, 1);
+  closure->error_data.error = error;
+  gpr_mpscq_push(&pi->workqueue_items, &closure->next_data.atm_next);
+  if (last == 0) {
+    workqueue_maybe_wakeup(pi);
+  }
+  workqueue_move_items_to_parent(pi);
+  GRPC_WORKQUEUE_UNREF(exec_ctx, workqueue, "enqueue");
+  GPR_TIMER_END("workqueue.enqueue", 0);
+}
+
 static grpc_error *polling_island_global_init() {
   grpc_error *error = GRPC_ERROR_NONE;
 
@@ -1042,11 +1122,8 @@ static void fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
 
 static grpc_workqueue *fd_get_workqueue(grpc_fd *fd) {
   gpr_mu_lock(&fd->mu);
-  grpc_workqueue *workqueue = NULL;
-  if (fd->polling_island != NULL) {
-    workqueue =
-        GRPC_WORKQUEUE_REF(fd->polling_island->workqueue, "get_workqueue");
-  }
+  grpc_workqueue *workqueue = GRPC_WORKQUEUE_REF(
+      (grpc_workqueue *)fd->polling_island, "fd_get_workqueue");
   gpr_mu_unlock(&fd->mu);
   return workqueue;
 }
@@ -1299,7 +1376,26 @@ static void pollset_reset(grpc_pollset *pollset) {
   GPR_ASSERT(pollset->polling_island == NULL);
 }
 
-#define GRPC_EPOLL_MAX_EVENTS 1000
+static bool maybe_do_workqueue_work(grpc_exec_ctx *exec_ctx,
+                                    polling_island *pi) {
+  if (gpr_mu_trylock(&pi->workqueue_read_mu)) {
+    gpr_mpscq_node *n = gpr_mpscq_pop(&pi->workqueue_items);
+    gpr_mu_unlock(&pi->workqueue_read_mu);
+    if (n != NULL) {
+      if (gpr_atm_full_fetch_add(&pi->workqueue_item_count, -1) > 1) {
+        workqueue_maybe_wakeup(pi);
+      }
+      grpc_closure *c = (grpc_closure *)n;
+      grpc_closure_run(exec_ctx, c, c->error_data.error);
+      return true;
+    } else if (gpr_atm_no_barrier_load(&pi->workqueue_item_count) > 0) {
+      workqueue_maybe_wakeup(pi);
+    }
+  }
+  return false;
+}
+
+#define GRPC_EPOLL_MAX_EVENTS 100
 /* Note: sig_mask contains the signal mask to use *during* epoll_wait() */
 static void pollset_work_and_unlock(grpc_exec_ctx *exec_ctx,
                                     grpc_pollset *pollset,
@@ -1354,7 +1450,10 @@ static void pollset_work_and_unlock(grpc_exec_ctx *exec_ctx,
   PI_ADD_REF(pi, "ps_work");
   gpr_mu_unlock(&pollset->mu);
 
-  do {
+  if (!maybe_do_workqueue_work(exec_ctx, pi)) {
+    gpr_atm_no_barrier_fetch_add(&pi->poller_count, 1);
+    g_current_thread_polling_island = pi;
+
     GRPC_SCHEDULING_START_BLOCKING_REGION;
     ep_rv = epoll_pwait(epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, timeout_ms,
                         sig_mask);
@@ -1386,6 +1485,11 @@ static void pollset_work_and_unlock(grpc_exec_ctx *exec_ctx,
         append_error(error,
                      grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd),
                      err_desc);
+      } else if (data_ptr == &pi->workqueue_wakeup_fd) {
+        append_error(error,
+                     grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd),
+                     err_desc);
+        maybe_do_workqueue_work(exec_ctx, pi);
       } else if (data_ptr == &polling_island_wakeup_fd) {
         GRPC_POLLING_TRACE(
             "pollset_work: pollset: %p, worker: %p polling island (epoll_fd: "
@@ -1408,7 +1512,10 @@ static void pollset_work_and_unlock(grpc_exec_ctx *exec_ctx,
         }
       }
     }
-  } while (ep_rv == GRPC_EPOLL_MAX_EVENTS);
+
+    g_current_thread_polling_island = NULL;
+    gpr_atm_no_barrier_fetch_add(&pi->poller_count, -1);
+  }
 
   GPR_ASSERT(pi != NULL);
 
@@ -1531,6 +1638,8 @@ static grpc_error *pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
 
 static void pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                            grpc_fd *fd) {
+  GPR_TIMER_BEGIN("pollset_add_fd", 0);
+
   grpc_error *error = GRPC_ERROR_NONE;
 
   gpr_mu_lock(&pollset->mu);
@@ -1643,6 +1752,8 @@ retry:
   gpr_mu_unlock(&pollset->mu);
 
   GRPC_LOG_IF_ERROR("pollset_add_fd", error);
+
+  GPR_TIMER_END("pollset_add_fd", 0);
 }
 
 /*******************************************************************************
@@ -1864,6 +1975,10 @@ static const grpc_event_engine_vtable vtable = {
 
     .kick_poller = kick_poller,
 
+    .workqueue_ref = workqueue_ref,
+    .workqueue_unref = workqueue_unref,
+    .workqueue_enqueue = workqueue_enqueue,
+
     .shutdown_engine = shutdown_engine,
 };
 

src/core/lib/iomgr/ev_poll_and_epoll_posix.c

@@ -1988,6 +1988,32 @@ static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
   gpr_mu_unlock(&pollset_set->mu);
 }
 
+/*******************************************************************************
+ * workqueue stubs
+ */
+
+#ifdef GRPC_WORKQUEUE_REFCOUNT_DEBUG
+static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue,
+                                     const char *file, int line,
+                                     const char *reason) {
+  return workqueue;
+}
+static void workqueue_unref(grpc_exec_ctx *exec_ctx, grpc_workqueue *workqueue,
+                            const char *file, int line, const char *reason) {}
+#else
+static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue) {
+  return workqueue;
+}
+static void workqueue_unref(grpc_exec_ctx *exec_ctx,
+                            grpc_workqueue *workqueue) {}
+#endif
+
+static void workqueue_enqueue(grpc_exec_ctx *exec_ctx,
+                              grpc_workqueue *workqueue, grpc_closure *closure,
+                              grpc_error *error) {
+  grpc_exec_ctx_sched(exec_ctx, closure, error, NULL);
+}
+
 /*******************************************************************************
  * event engine binding
  */
@@ -2029,6 +2055,10 @@ static const grpc_event_engine_vtable vtable = {
 
     .kick_poller = kick_poller,
 
+    .workqueue_ref = workqueue_ref,
+    .workqueue_unref = workqueue_unref,
+    .workqueue_enqueue = workqueue_enqueue,
+
     .shutdown_engine = shutdown_engine,
 };
 

src/core/lib/iomgr/ev_poll_posix.c

@@ -1235,6 +1235,32 @@ static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
   gpr_mu_unlock(&pollset_set->mu);
 }
 
+/*******************************************************************************
+ * workqueue stubs
+ */
+
+#ifdef GRPC_WORKQUEUE_REFCOUNT_DEBUG
+static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue,
+                                     const char *file, int line,
+                                     const char *reason) {
+  return workqueue;
+}
+static void workqueue_unref(grpc_exec_ctx *exec_ctx, grpc_workqueue *workqueue,
+                            const char *file, int line, const char *reason) {}
+#else
+static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue) {
+  return workqueue;
+}
+static void workqueue_unref(grpc_exec_ctx *exec_ctx,
+                            grpc_workqueue *workqueue) {}
+#endif
+
+static void workqueue_enqueue(grpc_exec_ctx *exec_ctx,
+                              grpc_workqueue *workqueue, grpc_closure *closure,
+                              grpc_error *error) {
+  grpc_exec_ctx_sched(exec_ctx, closure, error, NULL);
+}
+
 /*******************************************************************************
  * event engine binding
  */
@@ -1273,6 +1299,10 @@ static const grpc_event_engine_vtable vtable = {
 
     .kick_poller = kick_poller,
 
+    .workqueue_ref = workqueue_ref,
+    .workqueue_unref = workqueue_unref,
+    .workqueue_enqueue = workqueue_enqueue,
+
     .shutdown_engine = shutdown_engine,
 };