Merge branch 'master' of https://github.com/grpc/grpc into moiz-upb

BUILD

@@ -269,11 +269,14 @@ GRPCXX_PUBLIC_HDRS = [
     "include/grpcpp/server_posix.h",
     "include/grpcpp/server_posix_impl.h",
     "include/grpcpp/support/async_stream.h",
+    "include/grpcpp/support/async_stream_impl.h",
     "include/grpcpp/support/async_unary_call.h",
+    "include/grpcpp/support/async_unary_call_impl.h",
     "include/grpcpp/support/byte_buffer.h",
     "include/grpcpp/support/channel_arguments.h",
     "include/grpcpp/support/channel_arguments_impl.h",
     "include/grpcpp/support/client_callback.h",
+    "include/grpcpp/support/client_callback_impl.h",
     "include/grpcpp/support/client_interceptor.h",
     "include/grpcpp/support/config.h",
     "include/grpcpp/support/interceptor.h",
@@ -281,6 +284,7 @@ GRPCXX_PUBLIC_HDRS = [
     "include/grpcpp/support/proto_buffer_reader.h",
     "include/grpcpp/support/proto_buffer_writer.h",
     "include/grpcpp/support/server_callback.h",
+    "include/grpcpp/support/server_callback_impl.h",
     "include/grpcpp/support/server_interceptor.h",
     "include/grpcpp/support/slice.h",
     "include/grpcpp/support/status.h",
@@ -288,6 +292,7 @@ GRPCXX_PUBLIC_HDRS = [
     "include/grpcpp/support/string_ref.h",
     "include/grpcpp/support/stub_options.h",
     "include/grpcpp/support/sync_stream.h",
+    "include/grpcpp/support/sync_stream_impl.h",
     "include/grpcpp/support/time.h",
     "include/grpcpp/support/validate_service_config.h",    
 ]
@@ -2160,7 +2165,9 @@ grpc_cc_library(
         "include/grpc++/impl/codegen/time.h",
         "include/grpcpp/impl/codegen/async_generic_service.h",
         "include/grpcpp/impl/codegen/async_stream.h",
+        "include/grpcpp/impl/codegen/async_stream_impl.h",
         "include/grpcpp/impl/codegen/async_unary_call.h",
+        "include/grpcpp/impl/codegen/async_unary_call_impl.h",
         "include/grpcpp/impl/codegen/byte_buffer.h",
         "include/grpcpp/impl/codegen/call.h",
         "include/grpcpp/impl/codegen/call_hook.h",
@@ -2169,6 +2176,7 @@ grpc_cc_library(
         "include/grpcpp/impl/codegen/callback_common.h",
         "include/grpcpp/impl/codegen/channel_interface.h",
         "include/grpcpp/impl/codegen/client_callback.h",
+        "include/grpcpp/impl/codegen/client_callback_impl.h",
         "include/grpcpp/impl/codegen/client_context.h",
         "include/grpcpp/impl/codegen/client_context_impl.h",
         "include/grpcpp/impl/codegen/client_interceptor.h",
@@ -2191,6 +2199,7 @@ grpc_cc_library(
         "include/grpcpp/impl/codegen/security/auth_context.h",
         "include/grpcpp/impl/codegen/serialization_traits.h",
         "include/grpcpp/impl/codegen/server_callback.h",
+        "include/grpcpp/impl/codegen/server_callback_impl.h",
         "include/grpcpp/impl/codegen/server_context.h",
         "include/grpcpp/impl/codegen/server_context_impl.h",
         "include/grpcpp/impl/codegen/server_interceptor.h",
@@ -2202,6 +2211,7 @@ grpc_cc_library(
         "include/grpcpp/impl/codegen/string_ref.h",
         "include/grpcpp/impl/codegen/stub_options.h",
         "include/grpcpp/impl/codegen/sync_stream.h",
+        "include/grpcpp/impl/codegen/sync_stream_impl.h",
         "include/grpcpp/impl/codegen/time.h",
     ],
     deps = [

BUILD.gn

@@ -1048,7 +1048,9 @@ config("grpc_config") {
         "include/grpcpp/impl/client_unary_call.h",
         "include/grpcpp/impl/codegen/async_generic_service.h",
         "include/grpcpp/impl/codegen/async_stream.h",
+        "include/grpcpp/impl/codegen/async_stream_impl.h",
         "include/grpcpp/impl/codegen/async_unary_call.h",
+        "include/grpcpp/impl/codegen/async_unary_call_impl.h",
         "include/grpcpp/impl/codegen/byte_buffer.h",
         "include/grpcpp/impl/codegen/call.h",
         "include/grpcpp/impl/codegen/call_hook.h",
@@ -1057,6 +1059,7 @@ config("grpc_config") {
         "include/grpcpp/impl/codegen/callback_common.h",
         "include/grpcpp/impl/codegen/channel_interface.h",
         "include/grpcpp/impl/codegen/client_callback.h",
+        "include/grpcpp/impl/codegen/client_callback_impl.h",
         "include/grpcpp/impl/codegen/client_context.h",
         "include/grpcpp/impl/codegen/client_context_impl.h",
         "include/grpcpp/impl/codegen/client_interceptor.h",
@@ -1085,6 +1088,7 @@ config("grpc_config") {
         "include/grpcpp/impl/codegen/security/auth_context.h",
         "include/grpcpp/impl/codegen/serialization_traits.h",
         "include/grpcpp/impl/codegen/server_callback.h",
+        "include/grpcpp/impl/codegen/server_callback_impl.h",
         "include/grpcpp/impl/codegen/server_context.h",
         "include/grpcpp/impl/codegen/server_context_impl.h",
         "include/grpcpp/impl/codegen/server_interceptor.h",
@@ -1097,6 +1101,7 @@ config("grpc_config") {
         "include/grpcpp/impl/codegen/stub_options.h",
         "include/grpcpp/impl/codegen/sync.h",
         "include/grpcpp/impl/codegen/sync_stream.h",
+        "include/grpcpp/impl/codegen/sync_stream_impl.h",
         "include/grpcpp/impl/codegen/time.h",
         "include/grpcpp/impl/grpc_library.h",
         "include/grpcpp/impl/method_handler_impl.h",
@@ -1126,11 +1131,14 @@ config("grpc_config") {
         "include/grpcpp/server_posix.h",
         "include/grpcpp/server_posix_impl.h",
         "include/grpcpp/support/async_stream.h",
+        "include/grpcpp/support/async_stream_impl.h",
         "include/grpcpp/support/async_unary_call.h",
+        "include/grpcpp/support/async_unary_call_impl.h",
         "include/grpcpp/support/byte_buffer.h",
         "include/grpcpp/support/channel_arguments.h",
         "include/grpcpp/support/channel_arguments_impl.h",
         "include/grpcpp/support/client_callback.h",
+        "include/grpcpp/support/client_callback_impl.h",
         "include/grpcpp/support/client_interceptor.h",
         "include/grpcpp/support/config.h",
         "include/grpcpp/support/interceptor.h",
@@ -1138,6 +1146,7 @@ config("grpc_config") {
         "include/grpcpp/support/proto_buffer_reader.h",
         "include/grpcpp/support/proto_buffer_writer.h",
         "include/grpcpp/support/server_callback.h",
+        "include/grpcpp/support/server_callback_impl.h",
         "include/grpcpp/support/server_interceptor.h",
         "include/grpcpp/support/slice.h",
         "include/grpcpp/support/status.h",
@@ -1145,6 +1154,7 @@ config("grpc_config") {
         "include/grpcpp/support/string_ref.h",
         "include/grpcpp/support/stub_options.h",
         "include/grpcpp/support/sync_stream.h",
+        "include/grpcpp/support/sync_stream_impl.h",
         "include/grpcpp/support/time.h",
         "include/grpcpp/support/validate_service_config.h",
         "src/core/ext/transport/inproc/inproc_transport.h",

CMakeLists.txt

@@ -3227,11 +3227,14 @@ foreach(_hdr
   include/grpcpp/server_posix.h
   include/grpcpp/server_posix_impl.h
   include/grpcpp/support/async_stream.h
+  include/grpcpp/support/async_stream_impl.h
   include/grpcpp/support/async_unary_call.h
+  include/grpcpp/support/async_unary_call_impl.h
   include/grpcpp/support/byte_buffer.h
   include/grpcpp/support/channel_arguments.h
   include/grpcpp/support/channel_arguments_impl.h
   include/grpcpp/support/client_callback.h
+  include/grpcpp/support/client_callback_impl.h
   include/grpcpp/support/client_interceptor.h
   include/grpcpp/support/config.h
   include/grpcpp/support/interceptor.h
@@ -3239,6 +3242,7 @@ foreach(_hdr
   include/grpcpp/support/proto_buffer_reader.h
   include/grpcpp/support/proto_buffer_writer.h
   include/grpcpp/support/server_callback.h
+  include/grpcpp/support/server_callback_impl.h
   include/grpcpp/support/server_interceptor.h
   include/grpcpp/support/slice.h
   include/grpcpp/support/status.h
@@ -3246,6 +3250,7 @@ foreach(_hdr
   include/grpcpp/support/string_ref.h
   include/grpcpp/support/stub_options.h
   include/grpcpp/support/sync_stream.h
+  include/grpcpp/support/sync_stream_impl.h
   include/grpcpp/support/time.h
   include/grpcpp/support/validate_service_config.h
   include/grpc/support/alloc.h
@@ -3331,7 +3336,9 @@ foreach(_hdr
   include/grpc++/impl/codegen/time.h
   include/grpcpp/impl/codegen/async_generic_service.h
   include/grpcpp/impl/codegen/async_stream.h
+  include/grpcpp/impl/codegen/async_stream_impl.h
   include/grpcpp/impl/codegen/async_unary_call.h
+  include/grpcpp/impl/codegen/async_unary_call_impl.h
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
@@ -3340,6 +3347,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
+  include/grpcpp/impl/codegen/client_callback_impl.h
   include/grpcpp/impl/codegen/client_context.h
   include/grpcpp/impl/codegen/client_context_impl.h
   include/grpcpp/impl/codegen/client_interceptor.h
@@ -3362,6 +3370,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
   include/grpcpp/impl/codegen/server_callback.h
+  include/grpcpp/impl/codegen/server_callback_impl.h
   include/grpcpp/impl/codegen/server_context.h
   include/grpcpp/impl/codegen/server_context_impl.h
   include/grpcpp/impl/codegen/server_interceptor.h
@@ -3373,6 +3382,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/string_ref.h
   include/grpcpp/impl/codegen/stub_options.h
   include/grpcpp/impl/codegen/sync_stream.h
+  include/grpcpp/impl/codegen/sync_stream_impl.h
   include/grpcpp/impl/codegen/time.h
   include/grpcpp/impl/codegen/sync.h
   include/grpc++/impl/codegen/proto_utils.h
@@ -3853,11 +3863,14 @@ foreach(_hdr
   include/grpcpp/server_posix.h
   include/grpcpp/server_posix_impl.h
   include/grpcpp/support/async_stream.h
+  include/grpcpp/support/async_stream_impl.h
   include/grpcpp/support/async_unary_call.h
+  include/grpcpp/support/async_unary_call_impl.h
   include/grpcpp/support/byte_buffer.h
   include/grpcpp/support/channel_arguments.h
   include/grpcpp/support/channel_arguments_impl.h
   include/grpcpp/support/client_callback.h
+  include/grpcpp/support/client_callback_impl.h
   include/grpcpp/support/client_interceptor.h
   include/grpcpp/support/config.h
   include/grpcpp/support/interceptor.h
@@ -3865,6 +3878,7 @@ foreach(_hdr
   include/grpcpp/support/proto_buffer_reader.h
   include/grpcpp/support/proto_buffer_writer.h
   include/grpcpp/support/server_callback.h
+  include/grpcpp/support/server_callback_impl.h
   include/grpcpp/support/server_interceptor.h
   include/grpcpp/support/slice.h
   include/grpcpp/support/status.h
@@ -3872,6 +3886,7 @@ foreach(_hdr
   include/grpcpp/support/string_ref.h
   include/grpcpp/support/stub_options.h
   include/grpcpp/support/sync_stream.h
+  include/grpcpp/support/sync_stream_impl.h
   include/grpcpp/support/time.h
   include/grpcpp/support/validate_service_config.h
   include/grpc/support/alloc.h
@@ -3957,7 +3972,9 @@ foreach(_hdr
   include/grpc++/impl/codegen/time.h
   include/grpcpp/impl/codegen/async_generic_service.h
   include/grpcpp/impl/codegen/async_stream.h
+  include/grpcpp/impl/codegen/async_stream_impl.h
   include/grpcpp/impl/codegen/async_unary_call.h
+  include/grpcpp/impl/codegen/async_unary_call_impl.h
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
@@ -3966,6 +3983,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
+  include/grpcpp/impl/codegen/client_callback_impl.h
   include/grpcpp/impl/codegen/client_context.h
   include/grpcpp/impl/codegen/client_context_impl.h
   include/grpcpp/impl/codegen/client_interceptor.h
@@ -3988,6 +4006,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
   include/grpcpp/impl/codegen/server_callback.h
+  include/grpcpp/impl/codegen/server_callback_impl.h
   include/grpcpp/impl/codegen/server_context.h
   include/grpcpp/impl/codegen/server_context_impl.h
   include/grpcpp/impl/codegen/server_interceptor.h
@@ -3999,6 +4018,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/string_ref.h
   include/grpcpp/impl/codegen/stub_options.h
   include/grpcpp/impl/codegen/sync_stream.h
+  include/grpcpp/impl/codegen/sync_stream_impl.h
   include/grpcpp/impl/codegen/time.h
   include/grpcpp/impl/codegen/sync.h
   include/grpc/census.h
@@ -4394,7 +4414,9 @@ foreach(_hdr
   include/grpc++/impl/codegen/time.h
   include/grpcpp/impl/codegen/async_generic_service.h
   include/grpcpp/impl/codegen/async_stream.h
+  include/grpcpp/impl/codegen/async_stream_impl.h
   include/grpcpp/impl/codegen/async_unary_call.h
+  include/grpcpp/impl/codegen/async_unary_call_impl.h
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
@@ -4403,6 +4425,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
+  include/grpcpp/impl/codegen/client_callback_impl.h
   include/grpcpp/impl/codegen/client_context.h
   include/grpcpp/impl/codegen/client_context_impl.h
   include/grpcpp/impl/codegen/client_interceptor.h
@@ -4425,6 +4448,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
   include/grpcpp/impl/codegen/server_callback.h
+  include/grpcpp/impl/codegen/server_callback_impl.h
   include/grpcpp/impl/codegen/server_context.h
   include/grpcpp/impl/codegen/server_context_impl.h
   include/grpcpp/impl/codegen/server_interceptor.h
@@ -4436,6 +4460,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/string_ref.h
   include/grpcpp/impl/codegen/stub_options.h
   include/grpcpp/impl/codegen/sync_stream.h
+  include/grpcpp/impl/codegen/sync_stream_impl.h
   include/grpcpp/impl/codegen/time.h
   include/grpc/impl/codegen/byte_buffer.h
   include/grpc/impl/codegen/byte_buffer_reader.h
@@ -4595,7 +4620,9 @@ foreach(_hdr
   include/grpc++/impl/codegen/time.h
   include/grpcpp/impl/codegen/async_generic_service.h
   include/grpcpp/impl/codegen/async_stream.h
+  include/grpcpp/impl/codegen/async_stream_impl.h
   include/grpcpp/impl/codegen/async_unary_call.h
+  include/grpcpp/impl/codegen/async_unary_call_impl.h
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
@@ -4604,6 +4631,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
+  include/grpcpp/impl/codegen/client_callback_impl.h
   include/grpcpp/impl/codegen/client_context.h
   include/grpcpp/impl/codegen/client_context_impl.h
   include/grpcpp/impl/codegen/client_interceptor.h
@@ -4626,6 +4654,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
   include/grpcpp/impl/codegen/server_callback.h
+  include/grpcpp/impl/codegen/server_callback_impl.h
   include/grpcpp/impl/codegen/server_context.h
   include/grpcpp/impl/codegen/server_context_impl.h
   include/grpcpp/impl/codegen/server_interceptor.h
@@ -4637,6 +4666,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/string_ref.h
   include/grpcpp/impl/codegen/stub_options.h
   include/grpcpp/impl/codegen/sync_stream.h
+  include/grpcpp/impl/codegen/sync_stream_impl.h
   include/grpcpp/impl/codegen/time.h
   include/grpc/impl/codegen/byte_buffer.h
   include/grpc/impl/codegen/byte_buffer_reader.h
@@ -4853,11 +4883,14 @@ foreach(_hdr
   include/grpcpp/server_posix.h
   include/grpcpp/server_posix_impl.h
   include/grpcpp/support/async_stream.h
+  include/grpcpp/support/async_stream_impl.h
   include/grpcpp/support/async_unary_call.h
+  include/grpcpp/support/async_unary_call_impl.h
   include/grpcpp/support/byte_buffer.h
   include/grpcpp/support/channel_arguments.h
   include/grpcpp/support/channel_arguments_impl.h
   include/grpcpp/support/client_callback.h
+  include/grpcpp/support/client_callback_impl.h
   include/grpcpp/support/client_interceptor.h
   include/grpcpp/support/config.h
   include/grpcpp/support/interceptor.h
@@ -4865,6 +4898,7 @@ foreach(_hdr
   include/grpcpp/support/proto_buffer_reader.h
   include/grpcpp/support/proto_buffer_writer.h
   include/grpcpp/support/server_callback.h
+  include/grpcpp/support/server_callback_impl.h
   include/grpcpp/support/server_interceptor.h
   include/grpcpp/support/slice.h
   include/grpcpp/support/status.h
@@ -4872,6 +4906,7 @@ foreach(_hdr
   include/grpcpp/support/string_ref.h
   include/grpcpp/support/stub_options.h
   include/grpcpp/support/sync_stream.h
+  include/grpcpp/support/sync_stream_impl.h
   include/grpcpp/support/time.h
   include/grpcpp/support/validate_service_config.h
   include/grpc/support/alloc.h
@@ -4957,7 +4992,9 @@ foreach(_hdr
   include/grpc++/impl/codegen/time.h
   include/grpcpp/impl/codegen/async_generic_service.h
   include/grpcpp/impl/codegen/async_stream.h
+  include/grpcpp/impl/codegen/async_stream_impl.h
   include/grpcpp/impl/codegen/async_unary_call.h
+  include/grpcpp/impl/codegen/async_unary_call_impl.h
   include/grpcpp/impl/codegen/byte_buffer.h
   include/grpcpp/impl/codegen/call.h
   include/grpcpp/impl/codegen/call_hook.h
@@ -4966,6 +5003,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/callback_common.h
   include/grpcpp/impl/codegen/channel_interface.h
   include/grpcpp/impl/codegen/client_callback.h
+  include/grpcpp/impl/codegen/client_callback_impl.h
   include/grpcpp/impl/codegen/client_context.h
   include/grpcpp/impl/codegen/client_context_impl.h
   include/grpcpp/impl/codegen/client_interceptor.h
@@ -4988,6 +5026,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/security/auth_context.h
   include/grpcpp/impl/codegen/serialization_traits.h
   include/grpcpp/impl/codegen/server_callback.h
+  include/grpcpp/impl/codegen/server_callback_impl.h
   include/grpcpp/impl/codegen/server_context.h
   include/grpcpp/impl/codegen/server_context_impl.h
   include/grpcpp/impl/codegen/server_interceptor.h
@@ -4999,6 +5038,7 @@ foreach(_hdr
   include/grpcpp/impl/codegen/string_ref.h
   include/grpcpp/impl/codegen/stub_options.h
   include/grpcpp/impl/codegen/sync_stream.h
+  include/grpcpp/impl/codegen/sync_stream_impl.h
   include/grpcpp/impl/codegen/time.h
   include/grpcpp/impl/codegen/sync.h
 )

Makefile

@@ -5597,11 +5597,14 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/server_posix.h \
     include/grpcpp/server_posix_impl.h \
     include/grpcpp/support/async_stream.h \
+    include/grpcpp/support/async_stream_impl.h \
     include/grpcpp/support/async_unary_call.h \
+    include/grpcpp/support/async_unary_call_impl.h \
     include/grpcpp/support/byte_buffer.h \
     include/grpcpp/support/channel_arguments.h \
     include/grpcpp/support/channel_arguments_impl.h \
     include/grpcpp/support/client_callback.h \
+    include/grpcpp/support/client_callback_impl.h \
     include/grpcpp/support/client_interceptor.h \
     include/grpcpp/support/config.h \
     include/grpcpp/support/interceptor.h \
@@ -5609,6 +5612,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/proto_buffer_reader.h \
     include/grpcpp/support/proto_buffer_writer.h \
     include/grpcpp/support/server_callback.h \
+    include/grpcpp/support/server_callback_impl.h \
     include/grpcpp/support/server_interceptor.h \
     include/grpcpp/support/slice.h \
     include/grpcpp/support/status.h \
@@ -5616,6 +5620,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/string_ref.h \
     include/grpcpp/support/stub_options.h \
     include/grpcpp/support/sync_stream.h \
+    include/grpcpp/support/sync_stream_impl.h \
     include/grpcpp/support/time.h \
     include/grpcpp/support/validate_service_config.h \
     include/grpc/support/alloc.h \
@@ -5701,7 +5706,9 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/time.h \
     include/grpcpp/impl/codegen/async_generic_service.h \
     include/grpcpp/impl/codegen/async_stream.h \
+    include/grpcpp/impl/codegen/async_stream_impl.h \
     include/grpcpp/impl/codegen/async_unary_call.h \
+    include/grpcpp/impl/codegen/async_unary_call_impl.h \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
@@ -5710,6 +5717,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
+    include/grpcpp/impl/codegen/client_callback_impl.h \
     include/grpcpp/impl/codegen/client_context.h \
     include/grpcpp/impl/codegen/client_context_impl.h \
     include/grpcpp/impl/codegen/client_interceptor.h \
@@ -5732,6 +5740,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
     include/grpcpp/impl/codegen/server_callback.h \
+    include/grpcpp/impl/codegen/server_callback_impl.h \
     include/grpcpp/impl/codegen/server_context.h \
     include/grpcpp/impl/codegen/server_context_impl.h \
     include/grpcpp/impl/codegen/server_interceptor.h \
@@ -5743,6 +5752,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/string_ref.h \
     include/grpcpp/impl/codegen/stub_options.h \
     include/grpcpp/impl/codegen/sync_stream.h \
+    include/grpcpp/impl/codegen/sync_stream_impl.h \
     include/grpcpp/impl/codegen/time.h \
     include/grpcpp/impl/codegen/sync.h \
     include/grpc++/impl/codegen/proto_utils.h \
@@ -6228,11 +6238,14 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/server_posix.h \
     include/grpcpp/server_posix_impl.h \
     include/grpcpp/support/async_stream.h \
+    include/grpcpp/support/async_stream_impl.h \
     include/grpcpp/support/async_unary_call.h \
+    include/grpcpp/support/async_unary_call_impl.h \
     include/grpcpp/support/byte_buffer.h \
     include/grpcpp/support/channel_arguments.h \
     include/grpcpp/support/channel_arguments_impl.h \
     include/grpcpp/support/client_callback.h \
+    include/grpcpp/support/client_callback_impl.h \
     include/grpcpp/support/client_interceptor.h \
     include/grpcpp/support/config.h \
     include/grpcpp/support/interceptor.h \
@@ -6240,6 +6253,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/proto_buffer_reader.h \
     include/grpcpp/support/proto_buffer_writer.h \
     include/grpcpp/support/server_callback.h \
+    include/grpcpp/support/server_callback_impl.h \
     include/grpcpp/support/server_interceptor.h \
     include/grpcpp/support/slice.h \
     include/grpcpp/support/status.h \
@@ -6247,6 +6261,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/string_ref.h \
     include/grpcpp/support/stub_options.h \
     include/grpcpp/support/sync_stream.h \
+    include/grpcpp/support/sync_stream_impl.h \
     include/grpcpp/support/time.h \
     include/grpcpp/support/validate_service_config.h \
     include/grpc/support/alloc.h \
@@ -6332,7 +6347,9 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/time.h \
     include/grpcpp/impl/codegen/async_generic_service.h \
     include/grpcpp/impl/codegen/async_stream.h \
+    include/grpcpp/impl/codegen/async_stream_impl.h \
     include/grpcpp/impl/codegen/async_unary_call.h \
+    include/grpcpp/impl/codegen/async_unary_call_impl.h \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
@@ -6341,6 +6358,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
+    include/grpcpp/impl/codegen/client_callback_impl.h \
     include/grpcpp/impl/codegen/client_context.h \
     include/grpcpp/impl/codegen/client_context_impl.h \
     include/grpcpp/impl/codegen/client_interceptor.h \
@@ -6363,6 +6381,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
     include/grpcpp/impl/codegen/server_callback.h \
+    include/grpcpp/impl/codegen/server_callback_impl.h \
     include/grpcpp/impl/codegen/server_context.h \
     include/grpcpp/impl/codegen/server_context_impl.h \
     include/grpcpp/impl/codegen/server_interceptor.h \
@@ -6374,6 +6393,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/string_ref.h \
     include/grpcpp/impl/codegen/stub_options.h \
     include/grpcpp/impl/codegen/sync_stream.h \
+    include/grpcpp/impl/codegen/sync_stream_impl.h \
     include/grpcpp/impl/codegen/time.h \
     include/grpcpp/impl/codegen/sync.h \
     include/grpc/census.h \
@@ -6741,7 +6761,9 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/time.h \
     include/grpcpp/impl/codegen/async_generic_service.h \
     include/grpcpp/impl/codegen/async_stream.h \
+    include/grpcpp/impl/codegen/async_stream_impl.h \
     include/grpcpp/impl/codegen/async_unary_call.h \
+    include/grpcpp/impl/codegen/async_unary_call_impl.h \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
@@ -6750,6 +6772,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
+    include/grpcpp/impl/codegen/client_callback_impl.h \
     include/grpcpp/impl/codegen/client_context.h \
     include/grpcpp/impl/codegen/client_context_impl.h \
     include/grpcpp/impl/codegen/client_interceptor.h \
@@ -6772,6 +6795,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
     include/grpcpp/impl/codegen/server_callback.h \
+    include/grpcpp/impl/codegen/server_callback_impl.h \
     include/grpcpp/impl/codegen/server_context.h \
     include/grpcpp/impl/codegen/server_context_impl.h \
     include/grpcpp/impl/codegen/server_interceptor.h \
@@ -6783,6 +6807,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/string_ref.h \
     include/grpcpp/impl/codegen/stub_options.h \
     include/grpcpp/impl/codegen/sync_stream.h \
+    include/grpcpp/impl/codegen/sync_stream_impl.h \
     include/grpcpp/impl/codegen/time.h \
     include/grpc/impl/codegen/byte_buffer.h \
     include/grpc/impl/codegen/byte_buffer_reader.h \
@@ -6913,7 +6938,9 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/time.h \
     include/grpcpp/impl/codegen/async_generic_service.h \
     include/grpcpp/impl/codegen/async_stream.h \
+    include/grpcpp/impl/codegen/async_stream_impl.h \
     include/grpcpp/impl/codegen/async_unary_call.h \
+    include/grpcpp/impl/codegen/async_unary_call_impl.h \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
@@ -6922,6 +6949,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
+    include/grpcpp/impl/codegen/client_callback_impl.h \
     include/grpcpp/impl/codegen/client_context.h \
     include/grpcpp/impl/codegen/client_context_impl.h \
     include/grpcpp/impl/codegen/client_interceptor.h \
@@ -6944,6 +6972,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
     include/grpcpp/impl/codegen/server_callback.h \
+    include/grpcpp/impl/codegen/server_callback_impl.h \
     include/grpcpp/impl/codegen/server_context.h \
     include/grpcpp/impl/codegen/server_context_impl.h \
     include/grpcpp/impl/codegen/server_interceptor.h \
@@ -6955,6 +6984,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/string_ref.h \
     include/grpcpp/impl/codegen/stub_options.h \
     include/grpcpp/impl/codegen/sync_stream.h \
+    include/grpcpp/impl/codegen/sync_stream_impl.h \
     include/grpcpp/impl/codegen/time.h \
     include/grpc/impl/codegen/byte_buffer.h \
     include/grpc/impl/codegen/byte_buffer_reader.h \
@@ -7177,11 +7207,14 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/server_posix.h \
     include/grpcpp/server_posix_impl.h \
     include/grpcpp/support/async_stream.h \
+    include/grpcpp/support/async_stream_impl.h \
     include/grpcpp/support/async_unary_call.h \
+    include/grpcpp/support/async_unary_call_impl.h \
     include/grpcpp/support/byte_buffer.h \
     include/grpcpp/support/channel_arguments.h \
     include/grpcpp/support/channel_arguments_impl.h \
     include/grpcpp/support/client_callback.h \
+    include/grpcpp/support/client_callback_impl.h \
     include/grpcpp/support/client_interceptor.h \
     include/grpcpp/support/config.h \
     include/grpcpp/support/interceptor.h \
@@ -7189,6 +7222,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/proto_buffer_reader.h \
     include/grpcpp/support/proto_buffer_writer.h \
     include/grpcpp/support/server_callback.h \
+    include/grpcpp/support/server_callback_impl.h \
     include/grpcpp/support/server_interceptor.h \
     include/grpcpp/support/slice.h \
     include/grpcpp/support/status.h \
@@ -7196,6 +7230,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/support/string_ref.h \
     include/grpcpp/support/stub_options.h \
     include/grpcpp/support/sync_stream.h \
+    include/grpcpp/support/sync_stream_impl.h \
     include/grpcpp/support/time.h \
     include/grpcpp/support/validate_service_config.h \
     include/grpc/support/alloc.h \
@@ -7281,7 +7316,9 @@ PUBLIC_HEADERS_CXX += \
     include/grpc++/impl/codegen/time.h \
     include/grpcpp/impl/codegen/async_generic_service.h \
     include/grpcpp/impl/codegen/async_stream.h \
+    include/grpcpp/impl/codegen/async_stream_impl.h \
     include/grpcpp/impl/codegen/async_unary_call.h \
+    include/grpcpp/impl/codegen/async_unary_call_impl.h \
     include/grpcpp/impl/codegen/byte_buffer.h \
     include/grpcpp/impl/codegen/call.h \
     include/grpcpp/impl/codegen/call_hook.h \
@@ -7290,6 +7327,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/callback_common.h \
     include/grpcpp/impl/codegen/channel_interface.h \
     include/grpcpp/impl/codegen/client_callback.h \
+    include/grpcpp/impl/codegen/client_callback_impl.h \
     include/grpcpp/impl/codegen/client_context.h \
     include/grpcpp/impl/codegen/client_context_impl.h \
     include/grpcpp/impl/codegen/client_interceptor.h \
@@ -7312,6 +7350,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/security/auth_context.h \
     include/grpcpp/impl/codegen/serialization_traits.h \
     include/grpcpp/impl/codegen/server_callback.h \
+    include/grpcpp/impl/codegen/server_callback_impl.h \
     include/grpcpp/impl/codegen/server_context.h \
     include/grpcpp/impl/codegen/server_context_impl.h \
     include/grpcpp/impl/codegen/server_interceptor.h \
@@ -7323,6 +7362,7 @@ PUBLIC_HEADERS_CXX += \
     include/grpcpp/impl/codegen/string_ref.h \
     include/grpcpp/impl/codegen/stub_options.h \
     include/grpcpp/impl/codegen/sync_stream.h \
+    include/grpcpp/impl/codegen/sync_stream_impl.h \
     include/grpcpp/impl/codegen/time.h \
     include/grpcpp/impl/codegen/sync.h \
 

build.yaml

@@ -1253,7 +1253,9 @@ filegroups:
   - include/grpc++/impl/codegen/time.h
   - include/grpcpp/impl/codegen/async_generic_service.h
   - include/grpcpp/impl/codegen/async_stream.h
+  - include/grpcpp/impl/codegen/async_stream_impl.h
   - include/grpcpp/impl/codegen/async_unary_call.h
+  - include/grpcpp/impl/codegen/async_unary_call_impl.h
   - include/grpcpp/impl/codegen/byte_buffer.h
   - include/grpcpp/impl/codegen/call.h
   - include/grpcpp/impl/codegen/call_hook.h
@@ -1262,6 +1264,7 @@ filegroups:
   - include/grpcpp/impl/codegen/callback_common.h
   - include/grpcpp/impl/codegen/channel_interface.h
   - include/grpcpp/impl/codegen/client_callback.h
+  - include/grpcpp/impl/codegen/client_callback_impl.h
   - include/grpcpp/impl/codegen/client_context.h
   - include/grpcpp/impl/codegen/client_context_impl.h
   - include/grpcpp/impl/codegen/client_interceptor.h
@@ -1284,6 +1287,7 @@ filegroups:
   - include/grpcpp/impl/codegen/security/auth_context.h
   - include/grpcpp/impl/codegen/serialization_traits.h
   - include/grpcpp/impl/codegen/server_callback.h
+  - include/grpcpp/impl/codegen/server_callback_impl.h
   - include/grpcpp/impl/codegen/server_context.h
   - include/grpcpp/impl/codegen/server_context_impl.h
   - include/grpcpp/impl/codegen/server_interceptor.h
@@ -1295,6 +1299,7 @@ filegroups:
   - include/grpcpp/impl/codegen/string_ref.h
   - include/grpcpp/impl/codegen/stub_options.h
   - include/grpcpp/impl/codegen/sync_stream.h
+  - include/grpcpp/impl/codegen/sync_stream_impl.h
   - include/grpcpp/impl/codegen/time.h
   uses:
   - grpc_codegen
@@ -1413,11 +1418,14 @@ filegroups:
   - include/grpcpp/server_posix.h
   - include/grpcpp/server_posix_impl.h
   - include/grpcpp/support/async_stream.h
+  - include/grpcpp/support/async_stream_impl.h
   - include/grpcpp/support/async_unary_call.h
+  - include/grpcpp/support/async_unary_call_impl.h
   - include/grpcpp/support/byte_buffer.h
   - include/grpcpp/support/channel_arguments.h
   - include/grpcpp/support/channel_arguments_impl.h
   - include/grpcpp/support/client_callback.h
+  - include/grpcpp/support/client_callback_impl.h
   - include/grpcpp/support/client_interceptor.h
   - include/grpcpp/support/config.h
   - include/grpcpp/support/interceptor.h
@@ -1425,6 +1433,7 @@ filegroups:
   - include/grpcpp/support/proto_buffer_reader.h
   - include/grpcpp/support/proto_buffer_writer.h
   - include/grpcpp/support/server_callback.h
+  - include/grpcpp/support/server_callback_impl.h
   - include/grpcpp/support/server_interceptor.h
   - include/grpcpp/support/slice.h
   - include/grpcpp/support/status.h
@@ -1432,6 +1441,7 @@ filegroups:
   - include/grpcpp/support/string_ref.h
   - include/grpcpp/support/stub_options.h
   - include/grpcpp/support/sync_stream.h
+  - include/grpcpp/support/sync_stream_impl.h
   - include/grpcpp/support/time.h
   - include/grpcpp/support/validate_service_config.h
   headers:

gRPC-C++.podspec

@@ -129,11 +129,14 @@ Pod::Spec.new do |s|
                       'include/grpcpp/server_posix.h',
                       'include/grpcpp/server_posix_impl.h',
                       'include/grpcpp/support/async_stream.h',
+                      'include/grpcpp/support/async_stream_impl.h',
                       'include/grpcpp/support/async_unary_call.h',
+                      'include/grpcpp/support/async_unary_call_impl.h',
                       'include/grpcpp/support/byte_buffer.h',
                       'include/grpcpp/support/channel_arguments.h',
                       'include/grpcpp/support/channel_arguments_impl.h',
                       'include/grpcpp/support/client_callback.h',
+                      'include/grpcpp/support/client_callback_impl.h',
                       'include/grpcpp/support/client_interceptor.h',
                       'include/grpcpp/support/config.h',
                       'include/grpcpp/support/interceptor.h',
@@ -141,6 +144,7 @@ Pod::Spec.new do |s|
                       'include/grpcpp/support/proto_buffer_reader.h',
                       'include/grpcpp/support/proto_buffer_writer.h',
                       'include/grpcpp/support/server_callback.h',
+                      'include/grpcpp/support/server_callback_impl.h',
                       'include/grpcpp/support/server_interceptor.h',
                       'include/grpcpp/support/slice.h',
                       'include/grpcpp/support/status.h',
@@ -148,11 +152,14 @@ Pod::Spec.new do |s|
                       'include/grpcpp/support/string_ref.h',
                       'include/grpcpp/support/stub_options.h',
                       'include/grpcpp/support/sync_stream.h',
+                      'include/grpcpp/support/sync_stream_impl.h',
                       'include/grpcpp/support/time.h',
                       'include/grpcpp/support/validate_service_config.h',
                       'include/grpcpp/impl/codegen/async_generic_service.h',
                       'include/grpcpp/impl/codegen/async_stream.h',
+                      'include/grpcpp/impl/codegen/async_stream_impl.h',
                       'include/grpcpp/impl/codegen/async_unary_call.h',
+                      'include/grpcpp/impl/codegen/async_unary_call_impl.h',
                       'include/grpcpp/impl/codegen/byte_buffer.h',
                       'include/grpcpp/impl/codegen/call.h',
                       'include/grpcpp/impl/codegen/call_hook.h',
@@ -161,6 +168,7 @@ Pod::Spec.new do |s|
                       'include/grpcpp/impl/codegen/callback_common.h',
                       'include/grpcpp/impl/codegen/channel_interface.h',
                       'include/grpcpp/impl/codegen/client_callback.h',
+                      'include/grpcpp/impl/codegen/client_callback_impl.h',
                       'include/grpcpp/impl/codegen/client_context.h',
                       'include/grpcpp/impl/codegen/client_context_impl.h',
                       'include/grpcpp/impl/codegen/client_interceptor.h',
@@ -183,6 +191,7 @@ Pod::Spec.new do |s|
                       'include/grpcpp/impl/codegen/security/auth_context.h',
                       'include/grpcpp/impl/codegen/serialization_traits.h',
                       'include/grpcpp/impl/codegen/server_callback.h',
+                      'include/grpcpp/impl/codegen/server_callback_impl.h',
                       'include/grpcpp/impl/codegen/server_context.h',
                       'include/grpcpp/impl/codegen/server_context_impl.h',
                       'include/grpcpp/impl/codegen/server_interceptor.h',
@@ -194,6 +203,7 @@ Pod::Spec.new do |s|
                       'include/grpcpp/impl/codegen/string_ref.h',
                       'include/grpcpp/impl/codegen/stub_options.h',
                       'include/grpcpp/impl/codegen/sync_stream.h',
+                      'include/grpcpp/impl/codegen/sync_stream_impl.h',
                       'include/grpcpp/impl/codegen/time.h',
                       'include/grpcpp/impl/codegen/sync.h'
   end

include/grpcpp/channel_impl.h

@@ -26,7 +26,7 @@
 #include <grpcpp/impl/call.h>
 #include <grpcpp/impl/codegen/channel_interface.h>
 #include <grpcpp/impl/codegen/client_interceptor.h>
-#include <grpcpp/impl/codegen/completion_queue.h>
+#include <grpcpp/impl/codegen/completion_queue_impl.h>
 #include <grpcpp/impl/codegen/config.h>
 #include <grpcpp/impl/codegen/grpc_library.h>
 #include <grpcpp/impl/codegen/sync.h>
@@ -86,22 +86,23 @@ class Channel final : public ::grpc::ChannelInterface,
 
   ::grpc::internal::Call CreateCall(const ::grpc::internal::RpcMethod& method,
                                     ::grpc_impl::ClientContext* context,
-                                    ::grpc::CompletionQueue* cq) override;
+                                    ::grpc_impl::CompletionQueue* cq) override;
   void PerformOpsOnCall(::grpc::internal::CallOpSetInterface* ops,
                         ::grpc::internal::Call* call) override;
   void* RegisterMethod(const char* method) override;
 
   void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
                                gpr_timespec deadline,
-                               ::grpc::CompletionQueue* cq, void* tag) override;
+                               ::grpc_impl::CompletionQueue* cq,
+                               void* tag) override;
   bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
                               gpr_timespec deadline) override;
 
-  ::grpc::CompletionQueue* CallbackCQ() override;
+  ::grpc_impl::CompletionQueue* CallbackCQ() override;
 
   ::grpc::internal::Call CreateCallInternal(
       const ::grpc::internal::RpcMethod& method,
-      ::grpc_impl::ClientContext* context, ::grpc::CompletionQueue* cq,
+      ::grpc_impl::ClientContext* context, ::grpc_impl::CompletionQueue* cq,
       size_t interceptor_pos) override;
 
   const grpc::string host_;
@@ -114,7 +115,7 @@ class Channel final : public ::grpc::ChannelInterface,
   // with this channel (if any). It is set on the first call to CallbackCQ().
   // It is _not owned_ by the channel; ownership belongs with its internal
   // shutdown callback tag (invoked when the CQ is fully shutdown).
-  ::grpc::CompletionQueue* callback_cq_ = nullptr;
+  ::grpc_impl::CompletionQueue* callback_cq_ = nullptr;
 
   std::vector<
       std::unique_ptr<::grpc::experimental::ClientInterceptorFactoryInterface>>

include/grpcpp/generic/generic_stub_impl.h

@@ -22,17 +22,20 @@
 #include <functional>
 
 #include <grpcpp/client_context.h>
-#include <grpcpp/support/async_stream.h>
-#include <grpcpp/support/async_unary_call.h>
+#include <grpcpp/support/async_stream_impl.h>
+#include <grpcpp/support/async_unary_call_impl.h>
 #include <grpcpp/support/byte_buffer.h>
-#include <grpcpp/support/client_callback.h>
+#include <grpcpp/support/client_callback_impl.h>
 #include <grpcpp/support/status.h>
 
+#include <functional>
+
 namespace grpc {
 
-typedef ClientAsyncReaderWriter<ByteBuffer, ByteBuffer>
+typedef ::grpc_impl::ClientAsyncReaderWriter<ByteBuffer, ByteBuffer>
     GenericClientAsyncReaderWriter;
-typedef ClientAsyncResponseReader<ByteBuffer> GenericClientAsyncResponseReader;
+typedef ::grpc_impl::ClientAsyncResponseReader<ByteBuffer>
+    GenericClientAsyncResponseReader;
 }  // namespace grpc
 namespace grpc_impl {
 class CompletionQueue;
@@ -50,15 +53,15 @@ class GenericStub final {
   /// succeeded (i.e. the call won't proceed if the return value is nullptr).
   std::unique_ptr<grpc::GenericClientAsyncReaderWriter> PrepareCall(
       grpc::ClientContext* context, const grpc::string& method,
-      grpc::CompletionQueue* cq);
+      CompletionQueue* cq);
 
   /// Setup a unary call to a named method \a method using \a context, and don't
   /// start it. Let it be started explicitly with StartCall.
   /// The return value only indicates whether or not registration of the call
   /// succeeded (i.e. the call won't proceed if the return value is nullptr).
   std::unique_ptr<grpc::GenericClientAsyncResponseReader> PrepareUnaryCall(
-      grpc::ClientContext* context, const grpc::string& method,
-      const grpc::ByteBuffer& request, grpc::CompletionQueue* cq);
+      grpc_impl::ClientContext* context, const grpc::string& method,
+      const grpc::ByteBuffer& request, CompletionQueue* cq);
 
   /// DEPRECATED for multi-threaded use
   /// Begin a call to a named method \a method using \a context.
@@ -67,8 +70,8 @@ class GenericStub final {
   /// The return value only indicates whether or not registration of the call
   /// succeeded (i.e. the call won't proceed if the return value is nullptr).
   std::unique_ptr<grpc::GenericClientAsyncReaderWriter> Call(
-      grpc::ClientContext* context, const grpc::string& method,
-      grpc::CompletionQueue* cq, void* tag);
+      grpc_impl::ClientContext* context, const grpc::string& method,
+      CompletionQueue* cq, void* tag);
 
   /// NOTE: class experimental_type is not part of the public API of this class
   /// TODO(vjpai): Move these contents to the public API of GenericStub when
@@ -79,23 +82,25 @@ class GenericStub final {
 
     /// Setup and start a unary call to a named method \a method using
     /// \a context and specifying the \a request and \a response buffers.
-    void UnaryCall(grpc::ClientContext* context, const grpc::string& method,
-                   const grpc::ByteBuffer* request, grpc::ByteBuffer* response,
+    void UnaryCall(grpc_impl::ClientContext* context,
+                   const grpc::string& method, const grpc::ByteBuffer* request,
+                   grpc::ByteBuffer* response,
                    std::function<void(grpc::Status)> on_completion);
 
     /// Setup and start a unary call to a named method \a method using
     /// \a context and specifying the \a request and \a response buffers.
-    void UnaryCall(grpc::ClientContext* context, const grpc::string& method,
-                   const grpc::ByteBuffer* request, grpc::ByteBuffer* response,
-                   grpc::experimental::ClientUnaryReactor* reactor);
+    void UnaryCall(grpc_impl::ClientContext* context,
+                   const grpc::string& method, const grpc::ByteBuffer* request,
+                   grpc::ByteBuffer* response,
+                   grpc_impl::experimental::ClientUnaryReactor* reactor);
 
     /// Setup a call to a named method \a method using \a context and tied to
     /// \a reactor . Like any other bidi streaming RPC, it will not be activated
     /// until StartCall is invoked on its reactor.
     void PrepareBidiStreamingCall(
-        grpc::ClientContext* context, const grpc::string& method,
-        grpc::experimental::ClientBidiReactor<grpc::ByteBuffer,
-                                              grpc::ByteBuffer>* reactor);
+        grpc_impl::ClientContext* context, const grpc::string& method,
+        grpc_impl::experimental::ClientBidiReactor<grpc::ByteBuffer,
+                                                   grpc::ByteBuffer>* reactor);
 
    private:
     GenericStub* stub_;

include/grpcpp/impl/codegen/async_generic_service.h

@@ -19,19 +19,21 @@
 #ifndef GRPCPP_IMPL_CODEGEN_ASYNC_GENERIC_SERVICE_H
 #define GRPCPP_IMPL_CODEGEN_ASYNC_GENERIC_SERVICE_H
 
-#include <grpcpp/impl/codegen/async_stream.h>
+#include <grpcpp/impl/codegen/async_stream_impl.h>
 #include <grpcpp/impl/codegen/byte_buffer.h>
-#include <grpcpp/impl/codegen/server_callback.h>
+#include <grpcpp/impl/codegen/server_callback_impl.h>
 
 struct grpc_server;
 
 namespace grpc {
 
-typedef ServerAsyncReaderWriter<ByteBuffer, ByteBuffer>
+typedef ::grpc_impl::ServerAsyncReaderWriter<ByteBuffer, ByteBuffer>
     GenericServerAsyncReaderWriter;
-typedef ServerAsyncResponseWriter<ByteBuffer> GenericServerAsyncResponseWriter;
-typedef ServerAsyncReader<ByteBuffer, ByteBuffer> GenericServerAsyncReader;
-typedef ServerAsyncWriter<ByteBuffer> GenericServerAsyncWriter;
+typedef ::grpc_impl::ServerAsyncResponseWriter<ByteBuffer>
+    GenericServerAsyncResponseWriter;
+typedef ::grpc_impl::ServerAsyncReader<ByteBuffer, ByteBuffer>
+    GenericServerAsyncReader;
+typedef ::grpc_impl::ServerAsyncWriter<ByteBuffer> GenericServerAsyncWriter;
 
 class GenericServerContext final : public ::grpc_impl::ServerContext {
  public:
@@ -75,8 +77,9 @@ class AsyncGenericService final {
 
   void RequestCall(GenericServerContext* ctx,
                    GenericServerAsyncReaderWriter* reader_writer,
-                   CompletionQueue* call_cq,
-                   ServerCompletionQueue* notification_cq, void* tag);
+                   ::grpc_impl::CompletionQueue* call_cq,
+                   ::grpc_impl::ServerCompletionQueue* notification_cq,
+                   void* tag);
 
  private:
   friend class grpc_impl::Server;
@@ -91,7 +94,8 @@ namespace experimental {
 /// GenericServerContext rather than a ServerContext. All other reaction and
 /// operation initiation APIs are the same as ServerBidiReactor.
 class ServerGenericBidiReactor
-    : public ServerBidiReactor<ByteBuffer, ByteBuffer> {
+    : public ::grpc_impl::experimental::ServerBidiReactor<ByteBuffer,
+                                                          ByteBuffer> {
  public:
   /// Similar to ServerBidiReactor::OnStarted except for argument type.
   ///
@@ -137,8 +141,10 @@ class CallbackGenericService {
  private:
   friend class ::grpc_impl::Server;
 
-  internal::CallbackBidiHandler<ByteBuffer, ByteBuffer>* Handler() {
-    return new internal::CallbackBidiHandler<ByteBuffer, ByteBuffer>(
+  ::grpc_impl::internal::CallbackBidiHandler<ByteBuffer, ByteBuffer>*
+  Handler() {
+    return new ::grpc_impl::internal::CallbackBidiHandler<ByteBuffer,
+                                                          ByteBuffer>(
         [this] { return CreateReactor(); });
   }
 

include/grpcpp/impl/codegen/async_stream.h

@@ -19,1116 +19,76 @@
 #ifndef GRPCPP_IMPL_CODEGEN_ASYNC_STREAM_H
 #define GRPCPP_IMPL_CODEGEN_ASYNC_STREAM_H
 
-#include <grpcpp/impl/codegen/call.h>
-#include <grpcpp/impl/codegen/channel_interface.h>
-#include <grpcpp/impl/codegen/core_codegen_interface.h>
-#include <grpcpp/impl/codegen/server_context_impl.h>
-#include <grpcpp/impl/codegen/service_type.h>
-#include <grpcpp/impl/codegen/status.h>
+#include <grpcpp/impl/codegen/async_stream_impl.h>
 
 namespace grpc {
 
 namespace internal {
-/// Common interface for all client side asynchronous streaming.
-class ClientAsyncStreamingInterface {
- public:
-  virtual ~ClientAsyncStreamingInterface() {}
 
-  /// Start the call that was set up by the constructor, but only if the
-  /// constructor was invoked through the "Prepare" API which doesn't actually
-  /// start the call
-  virtual void StartCall(void* tag) = 0;
+typedef ::grpc_impl::internal::ClientAsyncStreamingInterface
+    ClientAsyncStreamingInterface;
 
-  /// Request notification of the reading of the initial metadata. Completion
-  /// will be notified by \a tag on the associated completion queue.
-  /// This call is optional, but if it is used, it cannot be used concurrently
-  /// with or after the \a AsyncReaderInterface::Read method.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  virtual void ReadInitialMetadata(void* tag) = 0;
-
-  /// Indicate that the stream is to be finished and request notification for
-  /// when the call has been ended.
-  /// Should not be used concurrently with other operations.
-  ///
-  /// It is appropriate to call this method when both:
-  ///   * the client side has no more message to send
-  ///     (this can be declared implicitly by calling this method, or
-  ///     explicitly through an earlier call to the <i>WritesDone</i> method
-  ///     of the class in use, e.g. \a ClientAsyncWriterInterface::WritesDone or
-  ///     \a ClientAsyncReaderWriterInterface::WritesDone).
-  ///   * there are no more messages to be received from the server (this can
-  ///     be known implicitly by the calling code, or explicitly from an
-  ///     earlier call to \a AsyncReaderInterface::Read that yielded a failed
-  ///     result, e.g. cq->Next(&read_tag, &ok) filled in 'ok' with 'false').
-  ///
-  /// The tag will be returned when either:
-  /// - all incoming messages have been read and the server has returned
-  ///   a status.
-  /// - the server has returned a non-OK status.
-  /// - the call failed for some reason and the library generated a
-  ///   status.
-  ///
-  /// Note that implementations of this method attempt to receive initial
-  /// metadata from the server if initial metadata hasn't yet been received.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[out] status To be updated with the operation status.
-  virtual void Finish(Status* status, void* tag) = 0;
-};
-
-/// An interface that yields a sequence of messages of type \a R.
 template <class R>
-class AsyncReaderInterface {
- public:
-  virtual ~AsyncReaderInterface() {}
-
-  /// Read a message of type \a R into \a msg. Completion will be notified by \a
-  /// tag on the associated completion queue.
-  /// This is thread-safe with respect to \a Write or \a WritesDone methods. It
-  /// should not be called concurrently with other streaming APIs
-  /// on the same stream. It is not meaningful to call it concurrently
-  /// with another \a AsyncReaderInterface::Read on the same stream since reads
-  /// on the same stream are delivered in order.
-  ///
-  /// \param[out] msg Where to eventually store the read message.
-  /// \param[in] tag The tag identifying the operation.
-  ///
-  /// Side effect: note that this method attempt to receive initial metadata for
-  /// a stream if it hasn't yet been received.
-  virtual void Read(R* msg, void* tag) = 0;
-};
+using AsyncReaderInterface = ::grpc_impl::internal::AsyncReaderInterface<R>;
 
-/// An interface that can be fed a sequence of messages of type \a W.
 template <class W>
-class AsyncWriterInterface {
- public:
-  virtual ~AsyncWriterInterface() {}
-
-  /// Request the writing of \a msg with identifying tag \a tag.
-  ///
-  /// Only one write may be outstanding at any given time. This means that
-  /// after calling Write, one must wait to receive \a tag from the completion
-  /// queue BEFORE calling Write again.
-  /// This is thread-safe with respect to \a AsyncReaderInterface::Read
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg, so it is safe to
-  /// to deallocate once Write returns.
-  ///
-  /// \param[in] msg The message to be written.
-  /// \param[in] tag The tag identifying the operation.
-  virtual void Write(const W& msg, void* tag) = 0;
-
-  /// Request the writing of \a msg using WriteOptions \a options with
-  /// identifying tag \a tag.
-  ///
-  /// Only one write may be outstanding at any given time. This means that
-  /// after calling Write, one must wait to receive \a tag from the completion
-  /// queue BEFORE calling Write again.
-  /// WriteOptions \a options is used to set the write options of this message.
-  /// This is thread-safe with respect to \a AsyncReaderInterface::Read
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg, so it is safe to
-  /// to deallocate once Write returns.
-  ///
-  /// \param[in] msg The message to be written.
-  /// \param[in] options The WriteOptions to be used to write this message.
-  /// \param[in] tag The tag identifying the operation.
-  virtual void Write(const W& msg, WriteOptions options, void* tag) = 0;
-
-  /// Request the writing of \a msg and coalesce it with the writing
-  /// of trailing metadata, using WriteOptions \a options with
-  /// identifying tag \a tag.
-  ///
-  /// For client, WriteLast is equivalent of performing Write and
-  /// WritesDone in a single step.
-  /// For server, WriteLast buffers the \a msg. The writing of \a msg is held
-  /// until Finish is called, where \a msg and trailing metadata are coalesced
-  /// and write is initiated. Note that WriteLast can only buffer \a msg up to
-  /// the flow control window size. If \a msg size is larger than the window
-  /// size, it will be sent on wire without buffering.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg, so it is safe to
-  /// to deallocate once Write returns.
-  ///
-  /// \param[in] msg The message to be written.
-  /// \param[in] options The WriteOptions to be used to write this message.
-  /// \param[in] tag The tag identifying the operation.
-  void WriteLast(const W& msg, WriteOptions options, void* tag) {
-    Write(msg, options.set_last_message(), tag);
-  }
-};
+using AsyncWriterInterface = ::grpc_impl::internal::AsyncWriterInterface<W>;
 
 }  // namespace internal
 
 template <class R>
-class ClientAsyncReaderInterface
-    : public internal::ClientAsyncStreamingInterface,
-      public internal::AsyncReaderInterface<R> {};
+using ClientAsyncReaderInterface = ::grpc_impl::ClientAsyncReaderInterface<R>;
 
-namespace internal {
 template <class R>
-class ClientAsyncReaderFactory {
- public:
-  /// Create a stream object.
-  /// Write the first request out if \a start is set.
-  /// \a tag will be notified on \a cq when the call has been started and
-  /// \a request has been written out. If \a start is not set, \a tag must be
-  /// nullptr and the actual call must be initiated by StartCall
-  /// Note that \a context will be used to fill in custom initial metadata
-  /// used to send to the server when starting the call.
-  template <class W>
-  static ClientAsyncReader<R>* Create(ChannelInterface* channel,
-                                      CompletionQueue* cq,
-                                      const ::grpc::internal::RpcMethod& method,
-                                      ::grpc_impl::ClientContext* context,
-                                      const W& request, bool start, void* tag) {
-    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
-    return new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientAsyncReader<R>)))
-        ClientAsyncReader<R>(call, context, request, start, tag);
-  }
-};
-}  // namespace internal
-
-/// Async client-side API for doing server-streaming RPCs,
-/// where the incoming message stream coming from the server has
-/// messages of type \a R.
-template <class R>
-class ClientAsyncReader final : public ClientAsyncReaderInterface<R> {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientAsyncReader));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void StartCall(void* tag) override {
-    assert(!started_);
-    started_ = true;
-    StartCallInternal(tag);
-  }
-
-  /// See the \a ClientAsyncStreamingInterface.ReadInitialMetadata
-  /// method for semantics.
-  ///
-  /// Side effect:
-  ///   - upon receiving initial metadata from the server,
-  ///     the \a ClientContext associated with this call is updated, and the
-  ///     calling code can access the received metadata through the
-  ///     \a ClientContext.
-  void ReadInitialMetadata(void* tag) override {
-    assert(started_);
-    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
-
-    meta_ops_.set_output_tag(tag);
-    meta_ops_.RecvInitialMetadata(context_);
-    call_.PerformOps(&meta_ops_);
-  }
-
-  void Read(R* msg, void* tag) override {
-    assert(started_);
-    read_ops_.set_output_tag(tag);
-    if (!context_->initial_metadata_received_) {
-      read_ops_.RecvInitialMetadata(context_);
-    }
-    read_ops_.RecvMessage(msg);
-    call_.PerformOps(&read_ops_);
-  }
-
-  /// See the \a ClientAsyncStreamingInterface.Finish method for semantics.
-  ///
-  /// Side effect:
-  ///   - the \a ClientContext associated with this call is updated with
-  ///     possible initial and trailing metadata received from the server.
-  void Finish(Status* status, void* tag) override {
-    assert(started_);
-    finish_ops_.set_output_tag(tag);
-    if (!context_->initial_metadata_received_) {
-      finish_ops_.RecvInitialMetadata(context_);
-    }
-    finish_ops_.ClientRecvStatus(context_, status);
-    call_.PerformOps(&finish_ops_);
-  }
-
- private:
-  friend class internal::ClientAsyncReaderFactory<R>;
-  template <class W>
-  ClientAsyncReader(::grpc::internal::Call call,
-                    ::grpc_impl::ClientContext* context, const W& request,
-                    bool start, void* tag)
-      : context_(context), call_(call), started_(start) {
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(init_ops_.SendMessage(request).ok());
-    init_ops_.ClientSendClose();
-    if (start) {
-      StartCallInternal(tag);
-    } else {
-      assert(tag == nullptr);
-    }
-  }
-
-  void StartCallInternal(void* tag) {
-    init_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                  context_->initial_metadata_flags());
-    init_ops_.set_output_tag(tag);
-    call_.PerformOps(&init_ops_);
-  }
-
-  ::grpc_impl::ClientContext* context_;
-  ::grpc::internal::Call call_;
-  bool started_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpClientSendClose>
-      init_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
-      meta_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                              ::grpc::internal::CallOpRecvMessage<R>>
-      read_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                              ::grpc::internal::CallOpClientRecvStatus>
-      finish_ops_;
-};
-
-/// Common interface for client side asynchronous writing.
-template <class W>
-class ClientAsyncWriterInterface
-    : public internal::ClientAsyncStreamingInterface,
-      public internal::AsyncWriterInterface<W> {
- public:
-  /// Signal the client is done with the writes (half-close the client stream).
-  /// Thread-safe with respect to \a AsyncReaderInterface::Read
-  ///
-  /// \param[in] tag The tag identifying the operation.
-  virtual void WritesDone(void* tag) = 0;
-};
+using ClientAsyncReader = ::grpc_impl::ClientAsyncReader<R>;
 
-namespace internal {
 template <class W>
-class ClientAsyncWriterFactory {
- public:
-  /// Create a stream object.
-  /// Start the RPC if \a start is set
-  /// \a tag will be notified on \a cq when the call has been started (i.e.
-  /// intitial metadata sent) and \a request has been written out.
-  /// If \a start is not set, \a tag must be nullptr and the actual call
-  /// must be initiated by StartCall
-  /// Note that \a context will be used to fill in custom initial metadata
-  /// used to send to the server when starting the call.
-  /// \a response will be filled in with the single expected response
-  /// message from the server upon a successful call to the \a Finish
-  /// method of this instance.
-  template <class R>
-  static ClientAsyncWriter<W>* Create(ChannelInterface* channel,
-                                      CompletionQueue* cq,
-                                      const ::grpc::internal::RpcMethod& method,
-                                      ::grpc_impl::ClientContext* context,
-                                      R* response, bool start, void* tag) {
-    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
-    return new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientAsyncWriter<W>)))
-        ClientAsyncWriter<W>(call, context, response, start, tag);
-  }
-};
-}  // namespace internal
+using ClientAsyncWriterInterface = ::grpc_impl::ClientAsyncWriterInterface<W>;
 
-/// Async API on the client side for doing client-streaming RPCs,
-/// where the outgoing message stream going to the server contains
-/// messages of type \a W.
 template <class W>
-class ClientAsyncWriter final : public ClientAsyncWriterInterface<W> {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientAsyncWriter));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void StartCall(void* tag) override {
-    assert(!started_);
-    started_ = true;
-    StartCallInternal(tag);
-  }
-
-  /// See the \a ClientAsyncStreamingInterface.ReadInitialMetadata method for
-  /// semantics.
-  ///
-  /// Side effect:
-  ///   - upon receiving initial metadata from the server, the \a ClientContext
-  ///     associated with this call is updated, and the calling code can access
-  ///     the received metadata through the \a ClientContext.
-  void ReadInitialMetadata(void* tag) override {
-    assert(started_);
-    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
-
-    meta_ops_.set_output_tag(tag);
-    meta_ops_.RecvInitialMetadata(context_);
-    call_.PerformOps(&meta_ops_);
-  }
-
-  void Write(const W& msg, void* tag) override {
-    assert(started_);
-    write_ops_.set_output_tag(tag);
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
-    call_.PerformOps(&write_ops_);
-  }
-
-  void Write(const W& msg, WriteOptions options, void* tag) override {
-    assert(started_);
-    write_ops_.set_output_tag(tag);
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-      write_ops_.ClientSendClose();
-    }
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    call_.PerformOps(&write_ops_);
-  }
-
-  void WritesDone(void* tag) override {
-    assert(started_);
-    write_ops_.set_output_tag(tag);
-    write_ops_.ClientSendClose();
-    call_.PerformOps(&write_ops_);
-  }
-
-  /// See the \a ClientAsyncStreamingInterface.Finish method for semantics.
-  ///
-  /// Side effect:
-  ///   - the \a ClientContext associated with this call is updated with
-  ///     possible initial and trailing metadata received from the server.
-  ///   - attempts to fill in the \a response parameter passed to this class's
-  ///     constructor with the server's response message.
-  void Finish(Status* status, void* tag) override {
-    assert(started_);
-    finish_ops_.set_output_tag(tag);
-    if (!context_->initial_metadata_received_) {
-      finish_ops_.RecvInitialMetadata(context_);
-    }
-    finish_ops_.ClientRecvStatus(context_, status);
-    call_.PerformOps(&finish_ops_);
-  }
-
- private:
-  friend class internal::ClientAsyncWriterFactory<W>;
-  template <class R>
-  ClientAsyncWriter(::grpc::internal::Call call,
-                    ::grpc_impl::ClientContext* context, R* response,
-                    bool start, void* tag)
-      : context_(context), call_(call), started_(start) {
-    finish_ops_.RecvMessage(response);
-    finish_ops_.AllowNoMessage();
-    if (start) {
-      StartCallInternal(tag);
-    } else {
-      assert(tag == nullptr);
-    }
-  }
+using ClientAsyncWriter = ::grpc_impl::ClientAsyncWriter<W>;
 
-  void StartCallInternal(void* tag) {
-    write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                   context_->initial_metadata_flags());
-    // if corked bit is set in context, we just keep the initial metadata
-    // buffered up to coalesce with later message send. No op is performed.
-    if (!context_->initial_metadata_corked_) {
-      write_ops_.set_output_tag(tag);
-      call_.PerformOps(&write_ops_);
-    }
-  }
-
-  ::grpc_impl::ClientContext* context_;
-  ::grpc::internal::Call call_;
-  bool started_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
-      meta_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpClientSendClose>
-      write_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                              ::grpc::internal::CallOpGenericRecvMessage,
-                              ::grpc::internal::CallOpClientRecvStatus>
-      finish_ops_;
-};
-
-/// Async client-side interface for bi-directional streaming,
-/// where the client-to-server message stream has messages of type \a W,
-/// and the server-to-client message stream has messages of type \a R.
-template <class W, class R>
-class ClientAsyncReaderWriterInterface
-    : public internal::ClientAsyncStreamingInterface,
-      public internal::AsyncWriterInterface<W>,
-      public internal::AsyncReaderInterface<R> {
- public:
-  /// Signal the client is done with the writes (half-close the client stream).
-  /// Thread-safe with respect to \a AsyncReaderInterface::Read
-  ///
-  /// \param[in] tag The tag identifying the operation.
-  virtual void WritesDone(void* tag) = 0;
-};
-
-namespace internal {
 template <class W, class R>
-class ClientAsyncReaderWriterFactory {
- public:
-  /// Create a stream object.
-  /// Start the RPC request if \a start is set.
-  /// \a tag will be notified on \a cq when the call has been started (i.e.
-  /// intitial metadata sent). If \a start is not set, \a tag must be
-  /// nullptr and the actual call must be initiated by StartCall
-  /// Note that \a context will be used to fill in custom initial metadata
-  /// used to send to the server when starting the call.
-  static ClientAsyncReaderWriter<W, R>* Create(
-      ChannelInterface* channel, CompletionQueue* cq,
-      const ::grpc::internal::RpcMethod& method,
-      ::grpc_impl::ClientContext* context, bool start, void* tag) {
-    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
+using ClientAsyncReaderWriterInterface =
+    ::grpc_impl::ClientAsyncReaderWriterInterface<W, R>;
 
-    return new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientAsyncReaderWriter<W, R>)))
-        ClientAsyncReaderWriter<W, R>(call, context, start, tag);
-  }
-};
-}  // namespace internal
-
-/// Async client-side interface for bi-directional streaming,
-/// where the outgoing message stream going to the server
-/// has messages of type \a W,  and the incoming message stream coming
-/// from the server has messages of type \a R.
 template <class W, class R>
-class ClientAsyncReaderWriter final
-    : public ClientAsyncReaderWriterInterface<W, R> {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientAsyncReaderWriter));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void StartCall(void* tag) override {
-    assert(!started_);
-    started_ = true;
-    StartCallInternal(tag);
-  }
-
-  /// See the \a ClientAsyncStreamingInterface.ReadInitialMetadata method
-  /// for semantics of this method.
-  ///
-  /// Side effect:
-  ///   - upon receiving initial metadata from the server, the \a ClientContext
-  ///     is updated with it, and then the receiving initial metadata can
-  ///     be accessed through this \a ClientContext.
-  void ReadInitialMetadata(void* tag) override {
-    assert(started_);
-    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
-
-    meta_ops_.set_output_tag(tag);
-    meta_ops_.RecvInitialMetadata(context_);
-    call_.PerformOps(&meta_ops_);
-  }
-
-  void Read(R* msg, void* tag) override {
-    assert(started_);
-    read_ops_.set_output_tag(tag);
-    if (!context_->initial_metadata_received_) {
-      read_ops_.RecvInitialMetadata(context_);
-    }
-    read_ops_.RecvMessage(msg);
-    call_.PerformOps(&read_ops_);
-  }
-
-  void Write(const W& msg, void* tag) override {
-    assert(started_);
-    write_ops_.set_output_tag(tag);
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
-    call_.PerformOps(&write_ops_);
-  }
-
-  void Write(const W& msg, WriteOptions options, void* tag) override {
-    assert(started_);
-    write_ops_.set_output_tag(tag);
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-      write_ops_.ClientSendClose();
-    }
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    call_.PerformOps(&write_ops_);
-  }
-
-  void WritesDone(void* tag) override {
-    assert(started_);
-    write_ops_.set_output_tag(tag);
-    write_ops_.ClientSendClose();
-    call_.PerformOps(&write_ops_);
-  }
-
-  /// See the \a ClientAsyncStreamingInterface.Finish method for semantics.
-  /// Side effect
-  ///   - the \a ClientContext associated with this call is updated with
-  ///     possible initial and trailing metadata sent from the server.
-  void Finish(Status* status, void* tag) override {
-    assert(started_);
-    finish_ops_.set_output_tag(tag);
-    if (!context_->initial_metadata_received_) {
-      finish_ops_.RecvInitialMetadata(context_);
-    }
-    finish_ops_.ClientRecvStatus(context_, status);
-    call_.PerformOps(&finish_ops_);
-  }
-
- private:
-  friend class internal::ClientAsyncReaderWriterFactory<W, R>;
-  ClientAsyncReaderWriter(::grpc::internal::Call call,
-                          ::grpc_impl::ClientContext* context, bool start,
-                          void* tag)
-      : context_(context), call_(call), started_(start) {
-    if (start) {
-      StartCallInternal(tag);
-    } else {
-      assert(tag == nullptr);
-    }
-  }
-
-  void StartCallInternal(void* tag) {
-    write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                   context_->initial_metadata_flags());
-    // if corked bit is set in context, we just keep the initial metadata
-    // buffered up to coalesce with later message send. No op is performed.
-    if (!context_->initial_metadata_corked_) {
-      write_ops_.set_output_tag(tag);
-      call_.PerformOps(&write_ops_);
-    }
-  }
-
-  ::grpc_impl::ClientContext* context_;
-  ::grpc::internal::Call call_;
-  bool started_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
-      meta_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                              ::grpc::internal::CallOpRecvMessage<R>>
-      read_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpClientSendClose>
-      write_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                              ::grpc::internal::CallOpClientRecvStatus>
-      finish_ops_;
-};
+using ClientAsyncReaderWriter = ::grpc_impl::ClientAsyncReaderWriter<W, R>;
 
 template <class W, class R>
-class ServerAsyncReaderInterface
-    : public internal::ServerAsyncStreamingInterface,
-      public internal::AsyncReaderInterface<R> {
- public:
-  /// Indicate that the stream is to be finished with a certain status code
-  /// and also send out \a msg response to the client.
-  /// Request notification for when the server has sent the response and the
-  /// appropriate signals to the client to end the call.
-  /// Should not be used concurrently with other operations.
-  ///
-  /// It is appropriate to call this method when:
-  ///   * all messages from the client have been received (either known
-  ///     implictly, or explicitly because a previous
-  ///     \a AsyncReaderInterface::Read operation with a non-ok result,
-  ///     e.g., cq->Next(&read_tag, &ok) filled in 'ok' with 'false').
-  ///
-  /// This operation will end when the server has finished sending out initial
-  /// metadata (if not sent already), response message, and status, or if
-  /// some failure occurred when trying to do so.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg or \a status, so it
-  /// is safe to deallocate once Finish returns.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[in] status To be sent to the client as the result of this call.
-  /// \param[in] msg To be sent to the client as the response for this call.
-  virtual void Finish(const W& msg, const Status& status, void* tag) = 0;
+using ServerAsyncReaderInterface =
+    ::grpc_impl::ServerAsyncReaderInterface<W, R>;
 
-  /// Indicate that the stream is to be finished with a certain
-  /// non-OK status code.
-  /// Request notification for when the server has sent the appropriate
-  /// signals to the client to end the call.
-  /// Should not be used concurrently with other operations.
-  ///
-  /// This call is meant to end the call with some error, and can be called at
-  /// any point that the server would like to "fail" the call (though note
-  /// this shouldn't be called concurrently with any other "sending" call, like
-  /// \a AsyncWriterInterface::Write).
-  ///
-  /// This operation will end when the server has finished sending out initial
-  /// metadata (if not sent already), and status, or if some failure occurred
-  /// when trying to do so.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
-  /// to deallocate once FinishWithError returns.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[in] status To be sent to the client as the result of this call.
-  ///     - Note: \a status must have a non-OK code.
-  virtual void FinishWithError(const Status& status, void* tag) = 0;
-};
-
-/// Async server-side API for doing client-streaming RPCs,
-/// where the incoming message stream from the client has messages of type \a R,
-/// and the single response message sent from the server is type \a W.
 template <class W, class R>
-class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
- public:
-  explicit ServerAsyncReader(::grpc_impl::ServerContext* ctx)
-      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
-
-  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
-  ///
-  /// Implicit input parameter:
-  ///   - The initial metadata that will be sent to the client from this op will
-  ///     be taken from the \a ServerContext associated with the call.
-  void SendInitialMetadata(void* tag) override {
-    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-    meta_ops_.set_output_tag(tag);
-    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                  ctx_->initial_metadata_flags());
-    if (ctx_->compression_level_set()) {
-      meta_ops_.set_compression_level(ctx_->compression_level());
-    }
-    ctx_->sent_initial_metadata_ = true;
-    call_.PerformOps(&meta_ops_);
-  }
-
-  void Read(R* msg, void* tag) override {
-    read_ops_.set_output_tag(tag);
-    read_ops_.RecvMessage(msg);
-    call_.PerformOps(&read_ops_);
-  }
-
-  /// See the \a ServerAsyncReaderInterface.Read method for semantics
-  ///
-  /// Side effect:
-  ///   - also sends initial metadata if not alreay sent.
-  ///   - uses the \a ServerContext associated with this call to send possible
-  ///     initial and trailing metadata.
-  ///
-  /// Note: \a msg is not sent if \a status has a non-OK code.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
-  /// is safe to deallocate once Finish returns.
-  void Finish(const W& msg, const Status& status, void* tag) override {
-    finish_ops_.set_output_tag(tag);
-    if (!ctx_->sent_initial_metadata_) {
-      finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                      ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        finish_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-    // The response is dropped if the status is not OK.
-    if (status.ok()) {
-      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
-                                   finish_ops_.SendMessage(msg));
-    } else {
-      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    }
-    call_.PerformOps(&finish_ops_);
-  }
-
-  /// See the \a ServerAsyncReaderInterface.Read method for semantics
-  ///
-  /// Side effect:
-  ///   - also sends initial metadata if not alreay sent.
-  ///   - uses the \a ServerContext associated with this call to send possible
-  ///     initial and trailing metadata.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
-  /// to deallocate once FinishWithError returns.
-  void FinishWithError(const Status& status, void* tag) override {
-    GPR_CODEGEN_ASSERT(!status.ok());
-    finish_ops_.set_output_tag(tag);
-    if (!ctx_->sent_initial_metadata_) {
-      finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                      ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        finish_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    call_.PerformOps(&finish_ops_);
-  }
-
- private:
-  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
-
-  ::grpc::internal::Call call_;
-  ::grpc_impl::ServerContext* ctx_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
-      meta_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>> read_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpServerSendStatus>
-      finish_ops_;
-};
+using ServerAsyncReader = ::grpc_impl::ServerAsyncReader<W, R>;
 
 template <class W>
-class ServerAsyncWriterInterface
-    : public internal::ServerAsyncStreamingInterface,
-      public internal::AsyncWriterInterface<W> {
- public:
-  /// Indicate that the stream is to be finished with a certain status code.
-  /// Request notification for when the server has sent the appropriate
-  /// signals to the client to end the call.
-  /// Should not be used concurrently with other operations.
-  ///
-  /// It is appropriate to call this method when either:
-  ///   * all messages from the client have been received (either known
-  ///     implictly, or explicitly because a previous \a
-  ///     AsyncReaderInterface::Read operation with a non-ok
-  ///     result (e.g., cq->Next(&read_tag, &ok) filled in 'ok' with 'false'.
-  ///   * it is desired to end the call early with some non-OK status code.
-  ///
-  /// This operation will end when the server has finished sending out initial
-  /// metadata (if not sent already), response message, and status, or if
-  /// some failure occurred when trying to do so.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
-  /// to deallocate once Finish returns.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[in] status To be sent to the client as the result of this call.
-  virtual void Finish(const Status& status, void* tag) = 0;
-
-  /// Request the writing of \a msg and coalesce it with trailing metadata which
-  /// contains \a status, using WriteOptions options with
-  /// identifying tag \a tag.
-  ///
-  /// WriteAndFinish is equivalent of performing WriteLast and Finish
-  /// in a single step.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
-  /// is safe to deallocate once WriteAndFinish returns.
-  ///
-  /// \param[in] msg The message to be written.
-  /// \param[in] options The WriteOptions to be used to write this message.
-  /// \param[in] status The Status that server returns to client.
-  /// \param[in] tag The tag identifying the operation.
-  virtual void WriteAndFinish(const W& msg, WriteOptions options,
-                              const Status& status, void* tag) = 0;
-};
+using ServerAsyncWriterInterface = ::grpc_impl::ServerAsyncWriterInterface<W>;
 
-/// Async server-side API for doing server streaming RPCs,
-/// where the outgoing message stream from the server has messages of type \a W.
 template <class W>
-class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
- public:
-  explicit ServerAsyncWriter(::grpc_impl::ServerContext* ctx)
-      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
-
-  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
-  ///
-  /// Implicit input parameter:
-  ///   - The initial metadata that will be sent to the client from this op will
-  ///     be taken from the \a ServerContext associated with the call.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  void SendInitialMetadata(void* tag) override {
-    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-    meta_ops_.set_output_tag(tag);
-    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                  ctx_->initial_metadata_flags());
-    if (ctx_->compression_level_set()) {
-      meta_ops_.set_compression_level(ctx_->compression_level());
-    }
-    ctx_->sent_initial_metadata_ = true;
-    call_.PerformOps(&meta_ops_);
-  }
-
-  void Write(const W& msg, void* tag) override {
-    write_ops_.set_output_tag(tag);
-    EnsureInitialMetadataSent(&write_ops_);
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
-    call_.PerformOps(&write_ops_);
-  }
+using ServerAsyncWriter = ::grpc_impl::ServerAsyncWriter<W>;
 
-  void Write(const W& msg, WriteOptions options, void* tag) override {
-    write_ops_.set_output_tag(tag);
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-    }
-
-    EnsureInitialMetadataSent(&write_ops_);
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    call_.PerformOps(&write_ops_);
-  }
-
-  /// See the \a ServerAsyncWriterInterface.WriteAndFinish method for semantics.
-  ///
-  /// Implicit input parameter:
-  ///   - the \a ServerContext associated with this call is used
-  ///     for sending trailing (and initial) metadata to the client.
-  ///
-  /// Note: \a status must have an OK code.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
-  /// is safe to deallocate once WriteAndFinish returns.
-  void WriteAndFinish(const W& msg, WriteOptions options, const Status& status,
-                      void* tag) override {
-    write_ops_.set_output_tag(tag);
-    EnsureInitialMetadataSent(&write_ops_);
-    options.set_buffer_hint();
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    write_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    call_.PerformOps(&write_ops_);
-  }
-
-  /// See the \a ServerAsyncWriterInterface.Finish method for semantics.
-  ///
-  /// Implicit input parameter:
-  ///   - the \a ServerContext associated with this call is used for sending
-  ///     trailing (and initial if not already sent) metadata to the client.
-  ///
-  /// Note: there are no restrictions are the code of
-  /// \a status,it may be non-OK
-  ///
-  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
-  /// to deallocate once Finish returns.
-  void Finish(const Status& status, void* tag) override {
-    finish_ops_.set_output_tag(tag);
-    EnsureInitialMetadataSent(&finish_ops_);
-    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    call_.PerformOps(&finish_ops_);
-  }
-
- private:
-  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
-
-  template <class T>
-  void EnsureInitialMetadataSent(T* ops) {
-    if (!ctx_->sent_initial_metadata_) {
-      ops->SendInitialMetadata(&ctx_->initial_metadata_,
-                               ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        ops->set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-  }
-
-  ::grpc::internal::Call call_;
-  ::grpc_impl::ServerContext* ctx_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
-      meta_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpServerSendStatus>
-      write_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpServerSendStatus>
-      finish_ops_;
-};
-
-/// Server-side interface for asynchronous bi-directional streaming.
 template <class W, class R>
-class ServerAsyncReaderWriterInterface
-    : public internal::ServerAsyncStreamingInterface,
-      public internal::AsyncWriterInterface<W>,
-      public internal::AsyncReaderInterface<R> {
- public:
-  /// Indicate that the stream is to be finished with a certain status code.
-  /// Request notification for when the server has sent the appropriate
-  /// signals to the client to end the call.
-  /// Should not be used concurrently with other operations.
-  ///
-  /// It is appropriate to call this method when either:
-  ///   * all messages from the client have been received (either known
-  ///     implictly, or explicitly because a previous \a
-  ///     AsyncReaderInterface::Read operation
-  ///     with a non-ok result (e.g., cq->Next(&read_tag, &ok) filled in 'ok'
-  ///     with 'false'.
-  ///   * it is desired to end the call early with some non-OK status code.
-  ///
-  /// This operation will end when the server has finished sending out initial
-  /// metadata (if not sent already), response message, and status, or if some
-  /// failure occurred when trying to do so.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
-  /// to deallocate once Finish returns.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[in] status To be sent to the client as the result of this call.
-  virtual void Finish(const Status& status, void* tag) = 0;
-
-  /// Request the writing of \a msg and coalesce it with trailing metadata which
-  /// contains \a status, using WriteOptions options with
-  /// identifying tag \a tag.
-  ///
-  /// WriteAndFinish is equivalent of performing WriteLast and Finish in a
-  /// single step.
-  ///
-  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
-  /// is safe to deallocate once WriteAndFinish returns.
-  ///
-  /// \param[in] msg The message to be written.
-  /// \param[in] options The WriteOptions to be used to write this message.
-  /// \param[in] status The Status that server returns to client.
-  /// \param[in] tag The tag identifying the operation.
-  virtual void WriteAndFinish(const W& msg, WriteOptions options,
-                              const Status& status, void* tag) = 0;
-};
+using ServerAsyncReaderWriterInterface =
+    ::grpc_impl::ServerAsyncReaderWriterInterface<W, R>;
 
-/// Async server-side API for doing bidirectional streaming RPCs,
-/// where the incoming message stream coming from the client has messages of
-/// type \a R, and the outgoing message stream coming from the server has
-/// messages of type \a W.
 template <class W, class R>
-class ServerAsyncReaderWriter final
-    : public ServerAsyncReaderWriterInterface<W, R> {
- public:
-  explicit ServerAsyncReaderWriter(::grpc_impl::ServerContext* ctx)
-      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
-
-  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
-  ///
-  /// Implicit input parameter:
-  ///   - The initial metadata that will be sent to the client from this op will
-  ///     be taken from the \a ServerContext associated with the call.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  void SendInitialMetadata(void* tag) override {
-    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-    meta_ops_.set_output_tag(tag);
-    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                  ctx_->initial_metadata_flags());
-    if (ctx_->compression_level_set()) {
-      meta_ops_.set_compression_level(ctx_->compression_level());
-    }
-    ctx_->sent_initial_metadata_ = true;
-    call_.PerformOps(&meta_ops_);
-  }
-
-  void Read(R* msg, void* tag) override {
-    read_ops_.set_output_tag(tag);
-    read_ops_.RecvMessage(msg);
-    call_.PerformOps(&read_ops_);
-  }
+using ServerAsyncReaderWriter = ::grpc_impl::ServerAsyncReaderWriter<W, R>;
 
-  void Write(const W& msg, void* tag) override {
-    write_ops_.set_output_tag(tag);
-    EnsureInitialMetadataSent(&write_ops_);
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
-    call_.PerformOps(&write_ops_);
-  }
-
-  void Write(const W& msg, WriteOptions options, void* tag) override {
-    write_ops_.set_output_tag(tag);
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-    }
-    EnsureInitialMetadataSent(&write_ops_);
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    call_.PerformOps(&write_ops_);
-  }
-
-  /// See the \a ServerAsyncReaderWriterInterface.WriteAndFinish
-  /// method for semantics.
-  ///
-  /// Implicit input parameter:
-  ///   - the \a ServerContext associated with this call is used
-  ///     for sending trailing (and initial) metadata to the client.
-  ///
-  /// Note: \a status must have an OK code.
-  //
-  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
-  /// is safe to deallocate once WriteAndFinish returns.
-  void WriteAndFinish(const W& msg, WriteOptions options, const Status& status,
-                      void* tag) override {
-    write_ops_.set_output_tag(tag);
-    EnsureInitialMetadataSent(&write_ops_);
-    options.set_buffer_hint();
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
-    write_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    call_.PerformOps(&write_ops_);
-  }
-
-  /// See the \a ServerAsyncReaderWriterInterface.Finish method for semantics.
-  ///
-  /// Implicit input parameter:
-  ///   - the \a ServerContext associated with this call is used for sending
-  ///     trailing (and initial if not already sent) metadata to the client.
-  ///
-  /// Note: there are no restrictions are the code of \a status,
-  /// it may be non-OK
-  //
-  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
-  /// to deallocate once Finish returns.
-  void Finish(const Status& status, void* tag) override {
-    finish_ops_.set_output_tag(tag);
-    EnsureInitialMetadataSent(&finish_ops_);
-
-    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    call_.PerformOps(&finish_ops_);
-  }
-
- private:
-  friend class ::grpc_impl::Server;
+namespace internal {
+template <class R>
+using ClientAsyncReaderFactory =
+    ::grpc_impl::internal::ClientAsyncReaderFactory<R>;
 
-  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
+template <class W>
+using ClientAsyncWriterFactory =
+    ::grpc_impl::internal::ClientAsyncWriterFactory<W>;
 
-  template <class T>
-  void EnsureInitialMetadataSent(T* ops) {
-    if (!ctx_->sent_initial_metadata_) {
-      ops->SendInitialMetadata(&ctx_->initial_metadata_,
-                               ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        ops->set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-  }
+template <class W, class R>
+using ClientAsyncReaderWriterFactory =
+    ::grpc_impl::internal::ClientAsyncReaderWriterFactory<W, R>;
 
-  ::grpc::internal::Call call_;
-  ::grpc_impl::ServerContext* ctx_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
-      meta_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>> read_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpServerSendStatus>
-      write_ops_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpServerSendStatus>
-      finish_ops_;
-};
+}  // namespace internal
 
 }  // namespace grpc
 

include/grpcpp/impl/codegen/async_stream_impl.h

@@ -0,0 +1,1134 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_ASYNC_STREAM_IMPL_H
+#define GRPCPP_IMPL_CODEGEN_ASYNC_STREAM_IMPL_H
+
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/channel_interface.h>
+#include <grpcpp/impl/codegen/core_codegen_interface.h>
+#include <grpcpp/impl/codegen/server_context_impl.h>
+#include <grpcpp/impl/codegen/service_type.h>
+#include <grpcpp/impl/codegen/status.h>
+
+namespace grpc_impl {
+
+namespace internal {
+/// Common interface for all client side asynchronous streaming.
+class ClientAsyncStreamingInterface {
+ public:
+  virtual ~ClientAsyncStreamingInterface() {}
+
+  /// Start the call that was set up by the constructor, but only if the
+  /// constructor was invoked through the "Prepare" API which doesn't actually
+  /// start the call
+  virtual void StartCall(void* tag) = 0;
+
+  /// Request notification of the reading of the initial metadata. Completion
+  /// will be notified by \a tag on the associated completion queue.
+  /// This call is optional, but if it is used, it cannot be used concurrently
+  /// with or after the \a AsyncReaderInterface::Read method.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  virtual void ReadInitialMetadata(void* tag) = 0;
+
+  /// Indicate that the stream is to be finished and request notification for
+  /// when the call has been ended.
+  /// Should not be used concurrently with other operations.
+  ///
+  /// It is appropriate to call this method when both:
+  ///   * the client side has no more message to send
+  ///     (this can be declared implicitly by calling this method, or
+  ///     explicitly through an earlier call to the <i>WritesDone</i> method
+  ///     of the class in use, e.g. \a ClientAsyncWriterInterface::WritesDone or
+  ///     \a ClientAsyncReaderWriterInterface::WritesDone).
+  ///   * there are no more messages to be received from the server (this can
+  ///     be known implicitly by the calling code, or explicitly from an
+  ///     earlier call to \a AsyncReaderInterface::Read that yielded a failed
+  ///     result, e.g. cq->Next(&read_tag, &ok) filled in 'ok' with 'false').
+  ///
+  /// The tag will be returned when either:
+  /// - all incoming messages have been read and the server has returned
+  ///   a status.
+  /// - the server has returned a non-OK status.
+  /// - the call failed for some reason and the library generated a
+  ///   status.
+  ///
+  /// Note that implementations of this method attempt to receive initial
+  /// metadata from the server if initial metadata hasn't yet been received.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[out] status To be updated with the operation status.
+  virtual void Finish(::grpc::Status* status, void* tag) = 0;
+};
+
+/// An interface that yields a sequence of messages of type \a R.
+template <class R>
+class AsyncReaderInterface {
+ public:
+  virtual ~AsyncReaderInterface() {}
+
+  /// Read a message of type \a R into \a msg. Completion will be notified by \a
+  /// tag on the associated completion queue.
+  /// This is thread-safe with respect to \a Write or \a WritesDone methods. It
+  /// should not be called concurrently with other streaming APIs
+  /// on the same stream. It is not meaningful to call it concurrently
+  /// with another \a AsyncReaderInterface::Read on the same stream since reads
+  /// on the same stream are delivered in order.
+  ///
+  /// \param[out] msg Where to eventually store the read message.
+  /// \param[in] tag The tag identifying the operation.
+  ///
+  /// Side effect: note that this method attempt to receive initial metadata for
+  /// a stream if it hasn't yet been received.
+  virtual void Read(R* msg, void* tag) = 0;
+};
+
+/// An interface that can be fed a sequence of messages of type \a W.
+template <class W>
+class AsyncWriterInterface {
+ public:
+  virtual ~AsyncWriterInterface() {}
+
+  /// Request the writing of \a msg with identifying tag \a tag.
+  ///
+  /// Only one write may be outstanding at any given time. This means that
+  /// after calling Write, one must wait to receive \a tag from the completion
+  /// queue BEFORE calling Write again.
+  /// This is thread-safe with respect to \a AsyncReaderInterface::Read
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg, so it is safe to
+  /// to deallocate once Write returns.
+  ///
+  /// \param[in] msg The message to be written.
+  /// \param[in] tag The tag identifying the operation.
+  virtual void Write(const W& msg, void* tag) = 0;
+
+  /// Request the writing of \a msg using WriteOptions \a options with
+  /// identifying tag \a tag.
+  ///
+  /// Only one write may be outstanding at any given time. This means that
+  /// after calling Write, one must wait to receive \a tag from the completion
+  /// queue BEFORE calling Write again.
+  /// WriteOptions \a options is used to set the write options of this message.
+  /// This is thread-safe with respect to \a AsyncReaderInterface::Read
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg, so it is safe to
+  /// to deallocate once Write returns.
+  ///
+  /// \param[in] msg The message to be written.
+  /// \param[in] options The WriteOptions to be used to write this message.
+  /// \param[in] tag The tag identifying the operation.
+  virtual void Write(const W& msg, ::grpc::WriteOptions options, void* tag) = 0;
+
+  /// Request the writing of \a msg and coalesce it with the writing
+  /// of trailing metadata, using WriteOptions \a options with
+  /// identifying tag \a tag.
+  ///
+  /// For client, WriteLast is equivalent of performing Write and
+  /// WritesDone in a single step.
+  /// For server, WriteLast buffers the \a msg. The writing of \a msg is held
+  /// until Finish is called, where \a msg and trailing metadata are coalesced
+  /// and write is initiated. Note that WriteLast can only buffer \a msg up to
+  /// the flow control window size. If \a msg size is larger than the window
+  /// size, it will be sent on wire without buffering.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg, so it is safe to
+  /// to deallocate once Write returns.
+  ///
+  /// \param[in] msg The message to be written.
+  /// \param[in] options The WriteOptions to be used to write this message.
+  /// \param[in] tag The tag identifying the operation.
+  void WriteLast(const W& msg, ::grpc::WriteOptions options, void* tag) {
+    Write(msg, options.set_last_message(), tag);
+  }
+};
+
+}  // namespace internal
+
+template <class R>
+class ClientAsyncReaderInterface
+    : public internal::ClientAsyncStreamingInterface,
+      public internal::AsyncReaderInterface<R> {};
+
+namespace internal {
+template <class R>
+class ClientAsyncReaderFactory {
+ public:
+  /// Create a stream object.
+  /// Write the first request out if \a start is set.
+  /// \a tag will be notified on \a cq when the call has been started and
+  /// \a request has been written out. If \a start is not set, \a tag must be
+  /// nullptr and the actual call must be initiated by StartCall
+  /// Note that \a context will be used to fill in custom initial metadata
+  /// used to send to the server when starting the call.
+  template <class W>
+  static ClientAsyncReader<R>* Create(::grpc::ChannelInterface* channel,
+                                      ::grpc_impl::CompletionQueue* cq,
+                                      const ::grpc::internal::RpcMethod& method,
+                                      ::grpc_impl::ClientContext* context,
+                                      const W& request, bool start, void* tag) {
+    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
+    return new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientAsyncReader<R>)))
+        ClientAsyncReader<R>(call, context, request, start, tag);
+  }
+};
+}  // namespace internal
+
+/// Async client-side API for doing server-streaming RPCs,
+/// where the incoming message stream coming from the server has
+/// messages of type \a R.
+template <class R>
+class ClientAsyncReader final : public ClientAsyncReaderInterface<R> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientAsyncReader));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void StartCall(void* tag) override {
+    assert(!started_);
+    started_ = true;
+    StartCallInternal(tag);
+  }
+
+  /// See the \a ClientAsyncStreamingInterface.ReadInitialMetadata
+  /// method for semantics.
+  ///
+  /// Side effect:
+  ///   - upon receiving initial metadata from the server,
+  ///     the \a ClientContext associated with this call is updated, and the
+  ///     calling code can access the received metadata through the
+  ///     \a ClientContext.
+  void ReadInitialMetadata(void* tag) override {
+    assert(started_);
+    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
+
+    meta_ops_.set_output_tag(tag);
+    meta_ops_.RecvInitialMetadata(context_);
+    call_.PerformOps(&meta_ops_);
+  }
+
+  void Read(R* msg, void* tag) override {
+    assert(started_);
+    read_ops_.set_output_tag(tag);
+    if (!context_->initial_metadata_received_) {
+      read_ops_.RecvInitialMetadata(context_);
+    }
+    read_ops_.RecvMessage(msg);
+    call_.PerformOps(&read_ops_);
+  }
+
+  /// See the \a ClientAsyncStreamingInterface.Finish method for semantics.
+  ///
+  /// Side effect:
+  ///   - the \a ClientContext associated with this call is updated with
+  ///     possible initial and trailing metadata received from the server.
+  void Finish(::grpc::Status* status, void* tag) override {
+    assert(started_);
+    finish_ops_.set_output_tag(tag);
+    if (!context_->initial_metadata_received_) {
+      finish_ops_.RecvInitialMetadata(context_);
+    }
+    finish_ops_.ClientRecvStatus(context_, status);
+    call_.PerformOps(&finish_ops_);
+  }
+
+ private:
+  friend class internal::ClientAsyncReaderFactory<R>;
+  template <class W>
+  ClientAsyncReader(::grpc::internal::Call call,
+                    ::grpc_impl::ClientContext* context, const W& request,
+                    bool start, void* tag)
+      : context_(context), call_(call), started_(start) {
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(init_ops_.SendMessage(request).ok());
+    init_ops_.ClientSendClose();
+    if (start) {
+      StartCallInternal(tag);
+    } else {
+      assert(tag == nullptr);
+    }
+  }
+
+  void StartCallInternal(void* tag) {
+    init_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                  context_->initial_metadata_flags());
+    init_ops_.set_output_tag(tag);
+    call_.PerformOps(&init_ops_);
+  }
+
+  ::grpc_impl::ClientContext* context_;
+  ::grpc::internal::Call call_;
+  bool started_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpClientSendClose>
+      init_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
+      meta_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                              ::grpc::internal::CallOpRecvMessage<R>>
+      read_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                              ::grpc::internal::CallOpClientRecvStatus>
+      finish_ops_;
+};
+
+/// Common interface for client side asynchronous writing.
+template <class W>
+class ClientAsyncWriterInterface
+    : public internal::ClientAsyncStreamingInterface,
+      public internal::AsyncWriterInterface<W> {
+ public:
+  /// Signal the client is done with the writes (half-close the client stream).
+  /// Thread-safe with respect to \a AsyncReaderInterface::Read
+  ///
+  /// \param[in] tag The tag identifying the operation.
+  virtual void WritesDone(void* tag) = 0;
+};
+
+namespace internal {
+template <class W>
+class ClientAsyncWriterFactory {
+ public:
+  /// Create a stream object.
+  /// Start the RPC if \a start is set
+  /// \a tag will be notified on \a cq when the call has been started (i.e.
+  /// intitial metadata sent) and \a request has been written out.
+  /// If \a start is not set, \a tag must be nullptr and the actual call
+  /// must be initiated by StartCall
+  /// Note that \a context will be used to fill in custom initial metadata
+  /// used to send to the server when starting the call.
+  /// \a response will be filled in with the single expected response
+  /// message from the server upon a successful call to the \a Finish
+  /// method of this instance.
+  template <class R>
+  static ClientAsyncWriter<W>* Create(::grpc::ChannelInterface* channel,
+                                      ::grpc_impl::CompletionQueue* cq,
+                                      const ::grpc::internal::RpcMethod& method,
+                                      ::grpc_impl::ClientContext* context,
+                                      R* response, bool start, void* tag) {
+    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
+    return new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientAsyncWriter<W>)))
+        ClientAsyncWriter<W>(call, context, response, start, tag);
+  }
+};
+}  // namespace internal
+
+/// Async API on the client side for doing client-streaming RPCs,
+/// where the outgoing message stream going to the server contains
+/// messages of type \a W.
+template <class W>
+class ClientAsyncWriter final : public ClientAsyncWriterInterface<W> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientAsyncWriter));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void StartCall(void* tag) override {
+    assert(!started_);
+    started_ = true;
+    StartCallInternal(tag);
+  }
+
+  /// See the \a ClientAsyncStreamingInterface.ReadInitialMetadata method for
+  /// semantics.
+  ///
+  /// Side effect:
+  ///   - upon receiving initial metadata from the server, the \a ClientContext
+  ///     associated with this call is updated, and the calling code can access
+  ///     the received metadata through the \a ClientContext.
+  void ReadInitialMetadata(void* tag) override {
+    assert(started_);
+    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
+
+    meta_ops_.set_output_tag(tag);
+    meta_ops_.RecvInitialMetadata(context_);
+    call_.PerformOps(&meta_ops_);
+  }
+
+  void Write(const W& msg, void* tag) override {
+    assert(started_);
+    write_ops_.set_output_tag(tag);
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  void Write(const W& msg, ::grpc::WriteOptions options, void* tag) override {
+    assert(started_);
+    write_ops_.set_output_tag(tag);
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      write_ops_.ClientSendClose();
+    }
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  void WritesDone(void* tag) override {
+    assert(started_);
+    write_ops_.set_output_tag(tag);
+    write_ops_.ClientSendClose();
+    call_.PerformOps(&write_ops_);
+  }
+
+  /// See the \a ClientAsyncStreamingInterface.Finish method for semantics.
+  ///
+  /// Side effect:
+  ///   - the \a ClientContext associated with this call is updated with
+  ///     possible initial and trailing metadata received from the server.
+  ///   - attempts to fill in the \a response parameter passed to this class's
+  ///     constructor with the server's response message.
+  void Finish(::grpc::Status* status, void* tag) override {
+    assert(started_);
+    finish_ops_.set_output_tag(tag);
+    if (!context_->initial_metadata_received_) {
+      finish_ops_.RecvInitialMetadata(context_);
+    }
+    finish_ops_.ClientRecvStatus(context_, status);
+    call_.PerformOps(&finish_ops_);
+  }
+
+ private:
+  friend class internal::ClientAsyncWriterFactory<W>;
+  template <class R>
+  ClientAsyncWriter(::grpc::internal::Call call,
+                    ::grpc_impl::ClientContext* context, R* response,
+                    bool start, void* tag)
+      : context_(context), call_(call), started_(start) {
+    finish_ops_.RecvMessage(response);
+    finish_ops_.AllowNoMessage();
+    if (start) {
+      StartCallInternal(tag);
+    } else {
+      assert(tag == nullptr);
+    }
+  }
+
+  void StartCallInternal(void* tag) {
+    write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                   context_->initial_metadata_flags());
+    // if corked bit is set in context, we just keep the initial metadata
+    // buffered up to coalesce with later message send. No op is performed.
+    if (!context_->initial_metadata_corked_) {
+      write_ops_.set_output_tag(tag);
+      call_.PerformOps(&write_ops_);
+    }
+  }
+
+  ::grpc_impl::ClientContext* context_;
+  ::grpc::internal::Call call_;
+  bool started_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
+      meta_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpClientSendClose>
+      write_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                              ::grpc::internal::CallOpGenericRecvMessage,
+                              ::grpc::internal::CallOpClientRecvStatus>
+      finish_ops_;
+};
+
+/// Async client-side interface for bi-directional streaming,
+/// where the client-to-server message stream has messages of type \a W,
+/// and the server-to-client message stream has messages of type \a R.
+template <class W, class R>
+class ClientAsyncReaderWriterInterface
+    : public internal::ClientAsyncStreamingInterface,
+      public internal::AsyncWriterInterface<W>,
+      public internal::AsyncReaderInterface<R> {
+ public:
+  /// Signal the client is done with the writes (half-close the client stream).
+  /// Thread-safe with respect to \a AsyncReaderInterface::Read
+  ///
+  /// \param[in] tag The tag identifying the operation.
+  virtual void WritesDone(void* tag) = 0;
+};
+
+namespace internal {
+template <class W, class R>
+class ClientAsyncReaderWriterFactory {
+ public:
+  /// Create a stream object.
+  /// Start the RPC request if \a start is set.
+  /// \a tag will be notified on \a cq when the call has been started (i.e.
+  /// intitial metadata sent). If \a start is not set, \a tag must be
+  /// nullptr and the actual call must be initiated by StartCall
+  /// Note that \a context will be used to fill in custom initial metadata
+  /// used to send to the server when starting the call.
+  static ClientAsyncReaderWriter<W, R>* Create(
+      ::grpc::ChannelInterface* channel, ::grpc_impl::CompletionQueue* cq,
+      const ::grpc::internal::RpcMethod& method,
+      ::grpc_impl::ClientContext* context, bool start, void* tag) {
+    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
+
+    return new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientAsyncReaderWriter<W, R>)))
+        ClientAsyncReaderWriter<W, R>(call, context, start, tag);
+  }
+};
+}  // namespace internal
+
+/// Async client-side interface for bi-directional streaming,
+/// where the outgoing message stream going to the server
+/// has messages of type \a W,  and the incoming message stream coming
+/// from the server has messages of type \a R.
+template <class W, class R>
+class ClientAsyncReaderWriter final
+    : public ClientAsyncReaderWriterInterface<W, R> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientAsyncReaderWriter));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void StartCall(void* tag) override {
+    assert(!started_);
+    started_ = true;
+    StartCallInternal(tag);
+  }
+
+  /// See the \a ClientAsyncStreamingInterface.ReadInitialMetadata method
+  /// for semantics of this method.
+  ///
+  /// Side effect:
+  ///   - upon receiving initial metadata from the server, the \a ClientContext
+  ///     is updated with it, and then the receiving initial metadata can
+  ///     be accessed through this \a ClientContext.
+  void ReadInitialMetadata(void* tag) override {
+    assert(started_);
+    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
+
+    meta_ops_.set_output_tag(tag);
+    meta_ops_.RecvInitialMetadata(context_);
+    call_.PerformOps(&meta_ops_);
+  }
+
+  void Read(R* msg, void* tag) override {
+    assert(started_);
+    read_ops_.set_output_tag(tag);
+    if (!context_->initial_metadata_received_) {
+      read_ops_.RecvInitialMetadata(context_);
+    }
+    read_ops_.RecvMessage(msg);
+    call_.PerformOps(&read_ops_);
+  }
+
+  void Write(const W& msg, void* tag) override {
+    assert(started_);
+    write_ops_.set_output_tag(tag);
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  void Write(const W& msg, ::grpc::WriteOptions options, void* tag) override {
+    assert(started_);
+    write_ops_.set_output_tag(tag);
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      write_ops_.ClientSendClose();
+    }
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  void WritesDone(void* tag) override {
+    assert(started_);
+    write_ops_.set_output_tag(tag);
+    write_ops_.ClientSendClose();
+    call_.PerformOps(&write_ops_);
+  }
+
+  /// See the \a ClientAsyncStreamingInterface.Finish method for semantics.
+  /// Side effect
+  ///   - the \a ClientContext associated with this call is updated with
+  ///     possible initial and trailing metadata sent from the server.
+  void Finish(::grpc::Status* status, void* tag) override {
+    assert(started_);
+    finish_ops_.set_output_tag(tag);
+    if (!context_->initial_metadata_received_) {
+      finish_ops_.RecvInitialMetadata(context_);
+    }
+    finish_ops_.ClientRecvStatus(context_, status);
+    call_.PerformOps(&finish_ops_);
+  }
+
+ private:
+  friend class internal::ClientAsyncReaderWriterFactory<W, R>;
+  ClientAsyncReaderWriter(::grpc::internal::Call call,
+                          ::grpc_impl::ClientContext* context, bool start,
+                          void* tag)
+      : context_(context), call_(call), started_(start) {
+    if (start) {
+      StartCallInternal(tag);
+    } else {
+      assert(tag == nullptr);
+    }
+  }
+
+  void StartCallInternal(void* tag) {
+    write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                   context_->initial_metadata_flags());
+    // if corked bit is set in context, we just keep the initial metadata
+    // buffered up to coalesce with later message send. No op is performed.
+    if (!context_->initial_metadata_corked_) {
+      write_ops_.set_output_tag(tag);
+      call_.PerformOps(&write_ops_);
+    }
+  }
+
+  ::grpc_impl::ClientContext* context_;
+  ::grpc::internal::Call call_;
+  bool started_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
+      meta_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                              ::grpc::internal::CallOpRecvMessage<R>>
+      read_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpClientSendClose>
+      write_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                              ::grpc::internal::CallOpClientRecvStatus>
+      finish_ops_;
+};
+
+template <class W, class R>
+class ServerAsyncReaderInterface
+    : public ::grpc::internal::ServerAsyncStreamingInterface,
+      public internal::AsyncReaderInterface<R> {
+ public:
+  /// Indicate that the stream is to be finished with a certain status code
+  /// and also send out \a msg response to the client.
+  /// Request notification for when the server has sent the response and the
+  /// appropriate signals to the client to end the call.
+  /// Should not be used concurrently with other operations.
+  ///
+  /// It is appropriate to call this method when:
+  ///   * all messages from the client have been received (either known
+  ///     implictly, or explicitly because a previous
+  ///     \a AsyncReaderInterface::Read operation with a non-ok result,
+  ///     e.g., cq->Next(&read_tag, &ok) filled in 'ok' with 'false').
+  ///
+  /// This operation will end when the server has finished sending out initial
+  /// metadata (if not sent already), response message, and status, or if
+  /// some failure occurred when trying to do so.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg or \a status, so it
+  /// is safe to deallocate once Finish returns.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[in] status To be sent to the client as the result of this call.
+  /// \param[in] msg To be sent to the client as the response for this call.
+  virtual void Finish(const W& msg, const ::grpc::Status& status,
+                      void* tag) = 0;
+
+  /// Indicate that the stream is to be finished with a certain
+  /// non-OK status code.
+  /// Request notification for when the server has sent the appropriate
+  /// signals to the client to end the call.
+  /// Should not be used concurrently with other operations.
+  ///
+  /// This call is meant to end the call with some error, and can be called at
+  /// any point that the server would like to "fail" the call (though note
+  /// this shouldn't be called concurrently with any other "sending" call, like
+  /// \a AsyncWriterInterface::Write).
+  ///
+  /// This operation will end when the server has finished sending out initial
+  /// metadata (if not sent already), and status, or if some failure occurred
+  /// when trying to do so.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once FinishWithError returns.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[in] status To be sent to the client as the result of this call.
+  ///     - Note: \a status must have a non-OK code.
+  virtual void FinishWithError(const ::grpc::Status& status, void* tag) = 0;
+};
+
+/// Async server-side API for doing client-streaming RPCs,
+/// where the incoming message stream from the client has messages of type \a R,
+/// and the single response message sent from the server is type \a W.
+template <class W, class R>
+class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
+ public:
+  explicit ServerAsyncReader(::grpc_impl::ServerContext* ctx)
+      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
+
+  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
+  ///
+  /// Implicit input parameter:
+  ///   - The initial metadata that will be sent to the client from this op will
+  ///     be taken from the \a ServerContext associated with the call.
+  void SendInitialMetadata(void* tag) override {
+    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+    meta_ops_.set_output_tag(tag);
+    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                  ctx_->initial_metadata_flags());
+    if (ctx_->compression_level_set()) {
+      meta_ops_.set_compression_level(ctx_->compression_level());
+    }
+    ctx_->sent_initial_metadata_ = true;
+    call_.PerformOps(&meta_ops_);
+  }
+
+  void Read(R* msg, void* tag) override {
+    read_ops_.set_output_tag(tag);
+    read_ops_.RecvMessage(msg);
+    call_.PerformOps(&read_ops_);
+  }
+
+  /// See the \a ServerAsyncReaderInterface.Read method for semantics
+  ///
+  /// Side effect:
+  ///   - also sends initial metadata if not alreay sent.
+  ///   - uses the \a ServerContext associated with this call to send possible
+  ///     initial and trailing metadata.
+  ///
+  /// Note: \a msg is not sent if \a status has a non-OK code.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to deallocate once Finish returns.
+  void Finish(const W& msg, const ::grpc::Status& status, void* tag) override {
+    finish_ops_.set_output_tag(tag);
+    if (!ctx_->sent_initial_metadata_) {
+      finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                      ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        finish_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+    // The response is dropped if the status is not OK.
+    if (status.ok()) {
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
+                                   finish_ops_.SendMessage(msg));
+    } else {
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    }
+    call_.PerformOps(&finish_ops_);
+  }
+
+  /// See the \a ServerAsyncReaderInterface.Read method for semantics
+  ///
+  /// Side effect:
+  ///   - also sends initial metadata if not alreay sent.
+  ///   - uses the \a ServerContext associated with this call to send possible
+  ///     initial and trailing metadata.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once FinishWithError returns.
+  void FinishWithError(const ::grpc::Status& status, void* tag) override {
+    GPR_CODEGEN_ASSERT(!status.ok());
+    finish_ops_.set_output_tag(tag);
+    if (!ctx_->sent_initial_metadata_) {
+      finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                      ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        finish_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    call_.PerformOps(&finish_ops_);
+  }
+
+ private:
+  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
+
+  ::grpc::internal::Call call_;
+  ::grpc_impl::ServerContext* ctx_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+      meta_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>> read_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpServerSendStatus>
+      finish_ops_;
+};
+
+template <class W>
+class ServerAsyncWriterInterface
+    : public ::grpc::internal::ServerAsyncStreamingInterface,
+      public internal::AsyncWriterInterface<W> {
+ public:
+  /// Indicate that the stream is to be finished with a certain status code.
+  /// Request notification for when the server has sent the appropriate
+  /// signals to the client to end the call.
+  /// Should not be used concurrently with other operations.
+  ///
+  /// It is appropriate to call this method when either:
+  ///   * all messages from the client have been received (either known
+  ///     implictly, or explicitly because a previous \a
+  ///     AsyncReaderInterface::Read operation with a non-ok
+  ///     result (e.g., cq->Next(&read_tag, &ok) filled in 'ok' with 'false'.
+  ///   * it is desired to end the call early with some non-OK status code.
+  ///
+  /// This operation will end when the server has finished sending out initial
+  /// metadata (if not sent already), response message, and status, or if
+  /// some failure occurred when trying to do so.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[in] status To be sent to the client as the result of this call.
+  virtual void Finish(const ::grpc::Status& status, void* tag) = 0;
+
+  /// Request the writing of \a msg and coalesce it with trailing metadata which
+  /// contains \a status, using WriteOptions options with
+  /// identifying tag \a tag.
+  ///
+  /// WriteAndFinish is equivalent of performing WriteLast and Finish
+  /// in a single step.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to deallocate once WriteAndFinish returns.
+  ///
+  /// \param[in] msg The message to be written.
+  /// \param[in] options The WriteOptions to be used to write this message.
+  /// \param[in] status The Status that server returns to client.
+  /// \param[in] tag The tag identifying the operation.
+  virtual void WriteAndFinish(const W& msg, ::grpc::WriteOptions options,
+                              const ::grpc::Status& status, void* tag) = 0;
+};
+
+/// Async server-side API for doing server streaming RPCs,
+/// where the outgoing message stream from the server has messages of type \a W.
+template <class W>
+class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
+ public:
+  explicit ServerAsyncWriter(::grpc_impl::ServerContext* ctx)
+      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
+
+  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
+  ///
+  /// Implicit input parameter:
+  ///   - The initial metadata that will be sent to the client from this op will
+  ///     be taken from the \a ServerContext associated with the call.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  void SendInitialMetadata(void* tag) override {
+    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+    meta_ops_.set_output_tag(tag);
+    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                  ctx_->initial_metadata_flags());
+    if (ctx_->compression_level_set()) {
+      meta_ops_.set_compression_level(ctx_->compression_level());
+    }
+    ctx_->sent_initial_metadata_ = true;
+    call_.PerformOps(&meta_ops_);
+  }
+
+  void Write(const W& msg, void* tag) override {
+    write_ops_.set_output_tag(tag);
+    EnsureInitialMetadataSent(&write_ops_);
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  void Write(const W& msg, ::grpc::WriteOptions options, void* tag) override {
+    write_ops_.set_output_tag(tag);
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+    }
+
+    EnsureInitialMetadataSent(&write_ops_);
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  /// See the \a ServerAsyncWriterInterface.WriteAndFinish method for semantics.
+  ///
+  /// Implicit input parameter:
+  ///   - the \a ServerContext associated with this call is used
+  ///     for sending trailing (and initial) metadata to the client.
+  ///
+  /// Note: \a status must have an OK code.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to deallocate once WriteAndFinish returns.
+  void WriteAndFinish(const W& msg, ::grpc::WriteOptions options,
+                      const ::grpc::Status& status, void* tag) override {
+    write_ops_.set_output_tag(tag);
+    EnsureInitialMetadataSent(&write_ops_);
+    options.set_buffer_hint();
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
+    write_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    call_.PerformOps(&write_ops_);
+  }
+
+  /// See the \a ServerAsyncWriterInterface.Finish method for semantics.
+  ///
+  /// Implicit input parameter:
+  ///   - the \a ServerContext associated with this call is used for sending
+  ///     trailing (and initial if not already sent) metadata to the client.
+  ///
+  /// Note: there are no restrictions are the code of
+  /// \a status,it may be non-OK
+  ///
+  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
+  void Finish(const ::grpc::Status& status, void* tag) override {
+    finish_ops_.set_output_tag(tag);
+    EnsureInitialMetadataSent(&finish_ops_);
+    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    call_.PerformOps(&finish_ops_);
+  }
+
+ private:
+  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
+
+  template <class T>
+  void EnsureInitialMetadataSent(T* ops) {
+    if (!ctx_->sent_initial_metadata_) {
+      ops->SendInitialMetadata(&ctx_->initial_metadata_,
+                               ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        ops->set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+  }
+
+  ::grpc::internal::Call call_;
+  ::grpc_impl::ServerContext* ctx_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+      meta_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpServerSendStatus>
+      write_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpServerSendStatus>
+      finish_ops_;
+};
+
+/// Server-side interface for asynchronous bi-directional streaming.
+template <class W, class R>
+class ServerAsyncReaderWriterInterface
+    : public ::grpc::internal::ServerAsyncStreamingInterface,
+      public internal::AsyncWriterInterface<W>,
+      public internal::AsyncReaderInterface<R> {
+ public:
+  /// Indicate that the stream is to be finished with a certain status code.
+  /// Request notification for when the server has sent the appropriate
+  /// signals to the client to end the call.
+  /// Should not be used concurrently with other operations.
+  ///
+  /// It is appropriate to call this method when either:
+  ///   * all messages from the client have been received (either known
+  ///     implictly, or explicitly because a previous \a
+  ///     AsyncReaderInterface::Read operation
+  ///     with a non-ok result (e.g., cq->Next(&read_tag, &ok) filled in 'ok'
+  ///     with 'false'.
+  ///   * it is desired to end the call early with some non-OK status code.
+  ///
+  /// This operation will end when the server has finished sending out initial
+  /// metadata (if not sent already), response message, and status, or if some
+  /// failure occurred when trying to do so.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[in] status To be sent to the client as the result of this call.
+  virtual void Finish(const ::grpc::Status& status, void* tag) = 0;
+
+  /// Request the writing of \a msg and coalesce it with trailing metadata which
+  /// contains \a status, using WriteOptions options with
+  /// identifying tag \a tag.
+  ///
+  /// WriteAndFinish is equivalent of performing WriteLast and Finish in a
+  /// single step.
+  ///
+  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to deallocate once WriteAndFinish returns.
+  ///
+  /// \param[in] msg The message to be written.
+  /// \param[in] options The WriteOptions to be used to write this message.
+  /// \param[in] status The Status that server returns to client.
+  /// \param[in] tag The tag identifying the operation.
+  virtual void WriteAndFinish(const W& msg, ::grpc::WriteOptions options,
+                              const ::grpc::Status& status, void* tag) = 0;
+};
+
+/// Async server-side API for doing bidirectional streaming RPCs,
+/// where the incoming message stream coming from the client has messages of
+/// type \a R, and the outgoing message stream coming from the server has
+/// messages of type \a W.
+template <class W, class R>
+class ServerAsyncReaderWriter final
+    : public ServerAsyncReaderWriterInterface<W, R> {
+ public:
+  explicit ServerAsyncReaderWriter(::grpc_impl::ServerContext* ctx)
+      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
+
+  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
+  ///
+  /// Implicit input parameter:
+  ///   - The initial metadata that will be sent to the client from this op will
+  ///     be taken from the \a ServerContext associated with the call.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  void SendInitialMetadata(void* tag) override {
+    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+    meta_ops_.set_output_tag(tag);
+    meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                  ctx_->initial_metadata_flags());
+    if (ctx_->compression_level_set()) {
+      meta_ops_.set_compression_level(ctx_->compression_level());
+    }
+    ctx_->sent_initial_metadata_ = true;
+    call_.PerformOps(&meta_ops_);
+  }
+
+  void Read(R* msg, void* tag) override {
+    read_ops_.set_output_tag(tag);
+    read_ops_.RecvMessage(msg);
+    call_.PerformOps(&read_ops_);
+  }
+
+  void Write(const W& msg, void* tag) override {
+    write_ops_.set_output_tag(tag);
+    EnsureInitialMetadataSent(&write_ops_);
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  void Write(const W& msg, ::grpc::WriteOptions options, void* tag) override {
+    write_ops_.set_output_tag(tag);
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+    }
+    EnsureInitialMetadataSent(&write_ops_);
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
+    call_.PerformOps(&write_ops_);
+  }
+
+  /// See the \a ServerAsyncReaderWriterInterface.WriteAndFinish
+  /// method for semantics.
+  ///
+  /// Implicit input parameter:
+  ///   - the \a ServerContext associated with this call is used
+  ///     for sending trailing (and initial) metadata to the client.
+  ///
+  /// Note: \a status must have an OK code.
+  //
+  /// gRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to deallocate once WriteAndFinish returns.
+  void WriteAndFinish(const W& msg, ::grpc::WriteOptions options,
+                      const ::grpc::Status& status, void* tag) override {
+    write_ops_.set_output_tag(tag);
+    EnsureInitialMetadataSent(&write_ops_);
+    options.set_buffer_hint();
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(msg, options).ok());
+    write_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    call_.PerformOps(&write_ops_);
+  }
+
+  /// See the \a ServerAsyncReaderWriterInterface.Finish method for semantics.
+  ///
+  /// Implicit input parameter:
+  ///   - the \a ServerContext associated with this call is used for sending
+  ///     trailing (and initial if not already sent) metadata to the client.
+  ///
+  /// Note: there are no restrictions are the code of \a status,
+  /// it may be non-OK
+  //
+  /// gRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
+  void Finish(const ::grpc::Status& status, void* tag) override {
+    finish_ops_.set_output_tag(tag);
+    EnsureInitialMetadataSent(&finish_ops_);
+
+    finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    call_.PerformOps(&finish_ops_);
+  }
+
+ private:
+  friend class ::grpc_impl::Server;
+
+  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
+
+  template <class T>
+  void EnsureInitialMetadataSent(T* ops) {
+    if (!ctx_->sent_initial_metadata_) {
+      ops->SendInitialMetadata(&ctx_->initial_metadata_,
+                               ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        ops->set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+  }
+
+  ::grpc::internal::Call call_;
+  ::grpc_impl::ServerContext* ctx_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+      meta_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>> read_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpServerSendStatus>
+      write_ops_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpServerSendStatus>
+      finish_ops_;
+};
+
+}  // namespace grpc_impl
+#endif  // GRPCPP_IMPL_CODEGEN_ASYNC_STREAM_IMPL_H

include/grpcpp/impl/codegen/async_unary_call.h

@@ -19,299 +19,28 @@
 #ifndef GRPCPP_IMPL_CODEGEN_ASYNC_UNARY_CALL_H
 #define GRPCPP_IMPL_CODEGEN_ASYNC_UNARY_CALL_H
 
-#include <assert.h>
-#include <grpcpp/impl/codegen/call.h>
-#include <grpcpp/impl/codegen/channel_interface.h>
-#include <grpcpp/impl/codegen/client_context_impl.h>
-#include <grpcpp/impl/codegen/server_context_impl.h>
-#include <grpcpp/impl/codegen/service_type.h>
-#include <grpcpp/impl/codegen/status.h>
+#include <grpcpp/impl/codegen/async_unary_call_impl.h>
 
 namespace grpc {
 
-extern CoreCodegenInterface* g_core_codegen_interface;
-
-/// An interface relevant for async client side unary RPCs (which send
-/// one request message to a server and receive one response message).
-template <class R>
-class ClientAsyncResponseReaderInterface {
- public:
-  virtual ~ClientAsyncResponseReaderInterface() {}
-
-  /// Start the call that was set up by the constructor, but only if the
-  /// constructor was invoked through the "Prepare" API which doesn't actually
-  /// start the call
-  virtual void StartCall() = 0;
-
-  /// Request notification of the reading of initial metadata. Completion
-  /// will be notified by \a tag on the associated completion queue.
-  /// This call is optional, but if it is used, it cannot be used concurrently
-  /// with or after the \a Finish method.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  virtual void ReadInitialMetadata(void* tag) = 0;
-
-  /// Request to receive the server's response \a msg and final \a status for
-  /// the call, and to notify \a tag on this call's completion queue when
-  /// finished.
-  ///
-  /// This function will return when either:
-  /// - when the server's response message and status have been received.
-  /// - when the server has returned a non-OK status (no message expected in
-  ///   this case).
-  /// - when the call failed for some reason and the library generated a
-  ///   non-OK status.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[out] status To be updated with the operation status.
-  /// \param[out] msg To be filled in with the server's response message.
-  virtual void Finish(R* msg, Status* status, void* tag) = 0;
-};
-
-namespace internal {
 template <class R>
-class ClientAsyncResponseReaderFactory {
- public:
-  /// Start a call and write the request out if \a start is set.
-  /// \a tag will be notified on \a cq when the call has been started (i.e.
-  /// intitial metadata sent) and \a request has been written out.
-  /// If \a start is not set, the actual call must be initiated by StartCall
-  /// Note that \a context will be used to fill in custom initial metadata
-  /// used to send to the server when starting the call.
-  template <class W>
-  static ClientAsyncResponseReader<R>* Create(
-      ChannelInterface* channel, ::grpc_impl::CompletionQueue* cq,
-      const ::grpc::internal::RpcMethod& method,
-      ::grpc_impl::ClientContext* context, const W& request, bool start) {
-    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
-    return new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientAsyncResponseReader<R>)))
-        ClientAsyncResponseReader<R>(call, context, request, start);
-  }
-};
-}  // namespace internal
+using ClientAsyncResponseReaderInterface =
+    grpc_impl::ClientAsyncResponseReaderInterface<R>;
 
-/// Async API for client-side unary RPCs, where the message response
-/// received from the server is of type \a R.
 template <class R>
-class ClientAsyncResponseReader final
-    : public ClientAsyncResponseReaderInterface<R> {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientAsyncResponseReader));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void StartCall() override {
-    assert(!started_);
-    started_ = true;
-    StartCallInternal();
-  }
-
-  /// See \a ClientAsyncResponseReaderInterface::ReadInitialMetadata for
-  /// semantics.
-  ///
-  /// Side effect:
-  ///   - the \a ClientContext associated with this call is updated with
-  ///     possible initial and trailing metadata sent from the server.
-  void ReadInitialMetadata(void* tag) override {
-    assert(started_);
-    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
-
-    single_buf.set_output_tag(tag);
-    single_buf.RecvInitialMetadata(context_);
-    call_.PerformOps(&single_buf);
-    initial_metadata_read_ = true;
-  }
-
-  /// See \a ClientAysncResponseReaderInterface::Finish for semantics.
-  ///
-  /// Side effect:
-  ///   - the \a ClientContext associated with this call is updated with
-  ///     possible initial and trailing metadata sent from the server.
-  void Finish(R* msg, Status* status, void* tag) override {
-    assert(started_);
-    if (initial_metadata_read_) {
-      finish_buf.set_output_tag(tag);
-      finish_buf.RecvMessage(msg);
-      finish_buf.AllowNoMessage();
-      finish_buf.ClientRecvStatus(context_, status);
-      call_.PerformOps(&finish_buf);
-    } else {
-      single_buf.set_output_tag(tag);
-      single_buf.RecvInitialMetadata(context_);
-      single_buf.RecvMessage(msg);
-      single_buf.AllowNoMessage();
-      single_buf.ClientRecvStatus(context_, status);
-      call_.PerformOps(&single_buf);
-    }
-  }
-
- private:
-  friend class internal::ClientAsyncResponseReaderFactory<R>;
-  ::grpc_impl::ClientContext* const context_;
-  ::grpc::internal::Call call_;
-  bool started_;
-  bool initial_metadata_read_ = false;
+using ClientAsyncResponseReader = grpc_impl::ClientAsyncResponseReader<R>;
 
-  template <class W>
-  ClientAsyncResponseReader(::grpc::internal::Call call,
-                            ::grpc_impl::ClientContext* context,
-                            const W& request, bool start)
-      : context_(context), call_(call), started_(start) {
-    // Bind the metadata at time of StartCallInternal but set up the rest here
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(single_buf.SendMessage(request).ok());
-    single_buf.ClientSendClose();
-    if (start) StartCallInternal();
-  }
-
-  void StartCallInternal() {
-    single_buf.SendInitialMetadata(&context_->send_initial_metadata_,
-                                   context_->initial_metadata_flags());
-  }
-
-  // disable operator new
-  static void* operator new(std::size_t size);
-  static void* operator new(std::size_t size, void* p) { return p; }
-
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpClientSendClose,
-                              ::grpc::internal::CallOpRecvInitialMetadata,
-                              ::grpc::internal::CallOpRecvMessage<R>,
-                              ::grpc::internal::CallOpClientRecvStatus>
-      single_buf;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>,
-                              ::grpc::internal::CallOpClientRecvStatus>
-      finish_buf;
-};
-
-/// Async server-side API for handling unary calls, where the single
-/// response message sent to the client is of type \a W.
 template <class W>
-class ServerAsyncResponseWriter final
-    : public internal::ServerAsyncStreamingInterface {
- public:
-  explicit ServerAsyncResponseWriter(::grpc_impl::ServerContext* ctx)
-      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
-
-  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
-  ///
-  /// Side effect:
-  ///   The initial metadata that will be sent to the client from this op will
-  ///   be taken from the \a ServerContext associated with the call.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  void SendInitialMetadata(void* tag) override {
-    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-    meta_buf_.set_output_tag(tag);
-    meta_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                  ctx_->initial_metadata_flags());
-    if (ctx_->compression_level_set()) {
-      meta_buf_.set_compression_level(ctx_->compression_level());
-    }
-    ctx_->sent_initial_metadata_ = true;
-    call_.PerformOps(&meta_buf_);
-  }
-
-  /// Indicate that the stream is to be finished and request notification
-  /// when the server has sent the appropriate signals to the client to
-  /// end the call. Should not be used concurrently with other operations.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[in] status To be sent to the client as the result of the call.
-  /// \param[in] msg Message to be sent to the client.
-  ///
-  /// Side effect:
-  ///   - also sends initial metadata if not already sent (using the
-  ///     \a ServerContext associated with this call).
-  ///
-  /// Note: if \a status has a non-OK code, then \a msg will not be sent,
-  /// and the client will receive only the status with possible trailing
-  /// metadata.
-  void Finish(const W& msg, const Status& status, void* tag) {
-    finish_buf_.set_output_tag(tag);
-    finish_buf_.set_core_cq_tag(&finish_buf_);
-    if (!ctx_->sent_initial_metadata_) {
-      finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                      ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        finish_buf_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-    // The response is dropped if the status is not OK.
-    if (status.ok()) {
-      finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_,
-                                   finish_buf_.SendMessage(msg));
-    } else {
-      finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    }
-    call_.PerformOps(&finish_buf_);
-  }
+using ServerAsyncResponseWriter = ::grpc_impl::ServerAsyncResponseWriter<W>;
 
-  /// Indicate that the stream is to be finished with a non-OK status,
-  /// and request notification for when the server has finished sending the
-  /// appropriate signals to the client to end the call.
-  /// Should not be used concurrently with other operations.
-  ///
-  /// \param[in] tag Tag identifying this request.
-  /// \param[in] status To be sent to the client as the result of the call.
-  ///   - Note: \a status must have a non-OK code.
-  ///
-  /// Side effect:
-  ///   - also sends initial metadata if not already sent (using the
-  ///     \a ServerContext associated with this call).
-  void FinishWithError(const Status& status, void* tag) {
-    GPR_CODEGEN_ASSERT(!status.ok());
-    finish_buf_.set_output_tag(tag);
-    if (!ctx_->sent_initial_metadata_) {
-      finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                      ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        finish_buf_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-    finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, status);
-    call_.PerformOps(&finish_buf_);
-  }
+namespace internal {
 
- private:
-  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
+template <class R>
+using ClientAsyncResponseReaderFactory =
+    ::grpc_impl::internal::ClientAsyncResponseReaderFactory<R>;
 
-  ::grpc::internal::Call call_;
-  ::grpc_impl::ServerContext* ctx_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
-      meta_buf_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                              ::grpc::internal::CallOpSendMessage,
-                              ::grpc::internal::CallOpServerSendStatus>
-      finish_buf_;
-};
+}  // namespace internal
 
 }  // namespace grpc
 
-namespace std {
-template <class R>
-class default_delete<grpc::ClientAsyncResponseReader<R>> {
- public:
-  void operator()(void* p) {}
-};
-template <class R>
-class default_delete<grpc::ClientAsyncResponseReaderInterface<R>> {
- public:
-  void operator()(void* p) {}
-};
-}  // namespace std
-
 #endif  // GRPCPP_IMPL_CODEGEN_ASYNC_UNARY_CALL_H

include/grpcpp/impl/codegen/async_unary_call_impl.h

@@ -0,0 +1,315 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_ASYNC_UNARY_CALL_IMPL_H
+#define GRPCPP_IMPL_CODEGEN_ASYNC_UNARY_CALL_IMPL_H
+
+#include <assert.h>
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/channel_interface.h>
+#include <grpcpp/impl/codegen/client_context_impl.h>
+#include <grpcpp/impl/codegen/server_context_impl.h>
+#include <grpcpp/impl/codegen/service_type.h>
+#include <grpcpp/impl/codegen/status.h>
+
+namespace grpc_impl {
+
+/// An interface relevant for async client side unary RPCs (which send
+/// one request message to a server and receive one response message).
+template <class R>
+class ClientAsyncResponseReaderInterface {
+ public:
+  virtual ~ClientAsyncResponseReaderInterface() {}
+
+  /// Start the call that was set up by the constructor, but only if the
+  /// constructor was invoked through the "Prepare" API which doesn't actually
+  /// start the call
+  virtual void StartCall() = 0;
+
+  /// Request notification of the reading of initial metadata. Completion
+  /// will be notified by \a tag on the associated completion queue.
+  /// This call is optional, but if it is used, it cannot be used concurrently
+  /// with or after the \a Finish method.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  virtual void ReadInitialMetadata(void* tag) = 0;
+
+  /// Request to receive the server's response \a msg and final \a status for
+  /// the call, and to notify \a tag on this call's completion queue when
+  /// finished.
+  ///
+  /// This function will return when either:
+  /// - when the server's response message and status have been received.
+  /// - when the server has returned a non-OK status (no message expected in
+  ///   this case).
+  /// - when the call failed for some reason and the library generated a
+  ///   non-OK status.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[out] status To be updated with the operation status.
+  /// \param[out] msg To be filled in with the server's response message.
+  virtual void Finish(R* msg, ::grpc::Status* status, void* tag) = 0;
+};
+
+namespace internal {
+template <class R>
+class ClientAsyncResponseReaderFactory {
+ public:
+  /// Start a call and write the request out if \a start is set.
+  /// \a tag will be notified on \a cq when the call has been started (i.e.
+  /// intitial metadata sent) and \a request has been written out.
+  /// If \a start is not set, the actual call must be initiated by StartCall
+  /// Note that \a context will be used to fill in custom initial metadata
+  /// used to send to the server when starting the call.
+  template <class W>
+  static ClientAsyncResponseReader<R>* Create(
+      ::grpc::ChannelInterface* channel, ::grpc_impl::CompletionQueue* cq,
+      const ::grpc::internal::RpcMethod& method,
+      ::grpc_impl::ClientContext* context, const W& request, bool start) {
+    ::grpc::internal::Call call = channel->CreateCall(method, context, cq);
+    return new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientAsyncResponseReader<R>)))
+        ClientAsyncResponseReader<R>(call, context, request, start);
+  }
+};
+}  // namespace internal
+
+/// Async API for client-side unary RPCs, where the message response
+/// received from the server is of type \a R.
+template <class R>
+class ClientAsyncResponseReader final
+    : public ClientAsyncResponseReaderInterface<R> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientAsyncResponseReader));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void StartCall() override {
+    assert(!started_);
+    started_ = true;
+    StartCallInternal();
+  }
+
+  /// See \a ClientAsyncResponseReaderInterface::ReadInitialMetadata for
+  /// semantics.
+  ///
+  /// Side effect:
+  ///   - the \a ClientContext associated with this call is updated with
+  ///     possible initial and trailing metadata sent from the server.
+  void ReadInitialMetadata(void* tag) override {
+    assert(started_);
+    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
+
+    single_buf.set_output_tag(tag);
+    single_buf.RecvInitialMetadata(context_);
+    call_.PerformOps(&single_buf);
+    initial_metadata_read_ = true;
+  }
+
+  /// See \a ClientAysncResponseReaderInterface::Finish for semantics.
+  ///
+  /// Side effect:
+  ///   - the \a ClientContext associated with this call is updated with
+  ///     possible initial and trailing metadata sent from the server.
+  void Finish(R* msg, ::grpc::Status* status, void* tag) override {
+    assert(started_);
+    if (initial_metadata_read_) {
+      finish_buf.set_output_tag(tag);
+      finish_buf.RecvMessage(msg);
+      finish_buf.AllowNoMessage();
+      finish_buf.ClientRecvStatus(context_, status);
+      call_.PerformOps(&finish_buf);
+    } else {
+      single_buf.set_output_tag(tag);
+      single_buf.RecvInitialMetadata(context_);
+      single_buf.RecvMessage(msg);
+      single_buf.AllowNoMessage();
+      single_buf.ClientRecvStatus(context_, status);
+      call_.PerformOps(&single_buf);
+    }
+  }
+
+ private:
+  friend class internal::ClientAsyncResponseReaderFactory<R>;
+  ::grpc_impl::ClientContext* const context_;
+  ::grpc::internal::Call call_;
+  bool started_;
+  bool initial_metadata_read_ = false;
+
+  template <class W>
+  ClientAsyncResponseReader(::grpc::internal::Call call,
+                            ::grpc_impl::ClientContext* context,
+                            const W& request, bool start)
+      : context_(context), call_(call), started_(start) {
+    // Bind the metadata at time of StartCallInternal but set up the rest here
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(single_buf.SendMessage(request).ok());
+    single_buf.ClientSendClose();
+    if (start) StartCallInternal();
+  }
+
+  void StartCallInternal() {
+    single_buf.SendInitialMetadata(&context_->send_initial_metadata_,
+                                   context_->initial_metadata_flags());
+  }
+
+  // disable operator new
+  static void* operator new(std::size_t size);
+  static void* operator new(std::size_t size, void* p) { return p; }
+
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpClientSendClose,
+                              ::grpc::internal::CallOpRecvInitialMetadata,
+                              ::grpc::internal::CallOpRecvMessage<R>,
+                              ::grpc::internal::CallOpClientRecvStatus>
+      single_buf;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>,
+                              ::grpc::internal::CallOpClientRecvStatus>
+      finish_buf;
+};
+
+/// Async server-side API for handling unary calls, where the single
+/// response message sent to the client is of type \a W.
+template <class W>
+class ServerAsyncResponseWriter final
+    : public ::grpc::internal::ServerAsyncStreamingInterface {
+ public:
+  explicit ServerAsyncResponseWriter(::grpc_impl::ServerContext* ctx)
+      : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
+
+  /// See \a ServerAsyncStreamingInterface::SendInitialMetadata for semantics.
+  ///
+  /// Side effect:
+  ///   The initial metadata that will be sent to the client from this op will
+  ///   be taken from the \a ServerContext associated with the call.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  void SendInitialMetadata(void* tag) override {
+    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+    meta_buf_.set_output_tag(tag);
+    meta_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                  ctx_->initial_metadata_flags());
+    if (ctx_->compression_level_set()) {
+      meta_buf_.set_compression_level(ctx_->compression_level());
+    }
+    ctx_->sent_initial_metadata_ = true;
+    call_.PerformOps(&meta_buf_);
+  }
+
+  /// Indicate that the stream is to be finished and request notification
+  /// when the server has sent the appropriate signals to the client to
+  /// end the call. Should not be used concurrently with other operations.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[in] status To be sent to the client as the result of the call.
+  /// \param[in] msg Message to be sent to the client.
+  ///
+  /// Side effect:
+  ///   - also sends initial metadata if not already sent (using the
+  ///     \a ServerContext associated with this call).
+  ///
+  /// Note: if \a status has a non-OK code, then \a msg will not be sent,
+  /// and the client will receive only the status with possible trailing
+  /// metadata.
+  void Finish(const W& msg, const ::grpc::Status& status, void* tag) {
+    finish_buf_.set_output_tag(tag);
+    finish_buf_.set_core_cq_tag(&finish_buf_);
+    if (!ctx_->sent_initial_metadata_) {
+      finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                      ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        finish_buf_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+    // The response is dropped if the status is not OK.
+    if (status.ok()) {
+      finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_,
+                                   finish_buf_.SendMessage(msg));
+    } else {
+      finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    }
+    call_.PerformOps(&finish_buf_);
+  }
+
+  /// Indicate that the stream is to be finished with a non-OK status,
+  /// and request notification for when the server has finished sending the
+  /// appropriate signals to the client to end the call.
+  /// Should not be used concurrently with other operations.
+  ///
+  /// \param[in] tag Tag identifying this request.
+  /// \param[in] status To be sent to the client as the result of the call.
+  ///   - Note: \a status must have a non-OK code.
+  ///
+  /// Side effect:
+  ///   - also sends initial metadata if not already sent (using the
+  ///     \a ServerContext associated with this call).
+  void FinishWithError(const ::grpc::Status& status, void* tag) {
+    GPR_CODEGEN_ASSERT(!status.ok());
+    finish_buf_.set_output_tag(tag);
+    if (!ctx_->sent_initial_metadata_) {
+      finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                      ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        finish_buf_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+    finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, status);
+    call_.PerformOps(&finish_buf_);
+  }
+
+ private:
+  void BindCall(::grpc::internal::Call* call) override { call_ = *call; }
+
+  ::grpc::internal::Call call_;
+  ::grpc_impl::ServerContext* ctx_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+      meta_buf_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                              ::grpc::internal::CallOpSendMessage,
+                              ::grpc::internal::CallOpServerSendStatus>
+      finish_buf_;
+};
+
+}  // namespace grpc_impl
+
+namespace std {
+template <class R>
+class default_delete<::grpc_impl::ClientAsyncResponseReader<R>> {
+ public:
+  void operator()(void* p) {}
+};
+template <class R>
+class default_delete<::grpc_impl::ClientAsyncResponseReaderInterface<R>> {
+ public:
+  void operator()(void* p) {}
+};
+}  // namespace std
+
+#endif  // GRPCPP_IMPL_CODEGEN_ASYNC_UNARY_CALL_IMPL_H

include/grpcpp/impl/codegen/byte_buffer.h

@@ -29,6 +29,17 @@
 
 #include <vector>
 
+namespace grpc_impl {
+namespace internal {
+
+template <class RequestType, class ResponseType>
+class CallbackUnaryHandler;
+template <class RequestType, class ResponseType>
+class CallbackServerStreamingHandler;
+
+}  // namespace internal
+}  // namespace grpc_impl
+
 namespace grpc {
 
 class ServerInterface;
@@ -45,10 +56,6 @@ template <class ServiceType, class RequestType, class ResponseType>
 class RpcMethodHandler;
 template <class ServiceType, class RequestType, class ResponseType>
 class ServerStreamingHandler;
-template <class RequestType, class ResponseType>
-class CallbackUnaryHandler;
-template <class RequestType, class ResponseType>
-class CallbackServerStreamingHandler;
 template <StatusCode code>
 class ErrorMethodHandler;
 class ExternalConnectionAcceptorImpl;
@@ -176,9 +183,9 @@ class ByteBuffer final {
   template <class ServiceType, class RequestType, class ResponseType>
   friend class internal::ServerStreamingHandler;
   template <class RequestType, class ResponseType>
-  friend class internal::CallbackUnaryHandler;
+  friend class ::grpc_impl::internal::CallbackUnaryHandler;
   template <class RequestType, class ResponseType>
-  friend class ::grpc::internal::CallbackServerStreamingHandler;
+  friend class ::grpc_impl::internal::CallbackServerStreamingHandler;
   template <StatusCode code>
   friend class internal::ErrorMethodHandler;
   template <class R>

include/grpcpp/impl/codegen/call_op_set.h

@@ -32,7 +32,7 @@
 #include <grpcpp/impl/codegen/call_hook.h>
 #include <grpcpp/impl/codegen/call_op_set_interface.h>
 #include <grpcpp/impl/codegen/client_context_impl.h>
-#include <grpcpp/impl/codegen/completion_queue.h>
+#include <grpcpp/impl/codegen/completion_queue_impl.h>
 #include <grpcpp/impl/codegen/completion_queue_tag.h>
 #include <grpcpp/impl/codegen/config.h>
 #include <grpcpp/impl/codegen/core_codegen_interface.h>

include/grpcpp/impl/codegen/channel_interface.h

@@ -27,24 +27,13 @@
 namespace grpc_impl {
 class ClientContext;
 class CompletionQueue;
-}  // namespace grpc_impl
-
-namespace grpc {
-class ChannelInterface;
-
 template <class R>
 class ClientReader;
 template <class W>
 class ClientWriter;
 template <class W, class R>
 class ClientReaderWriter;
-
 namespace internal {
-class Call;
-class CallOpSetInterface;
-class RpcMethod;
-template <class InputMessage, class OutputMessage>
-class BlockingUnaryCallImpl;
 template <class InputMessage, class OutputMessage>
 class CallbackUnaryCallImpl;
 template <class R>
@@ -62,7 +51,19 @@ class ClientCallbackReaderFactory;
 template <class W>
 class ClientCallbackWriterFactory;
 class ClientCallbackUnaryFactory;
+}  // namespace internal
+}  // namespace grpc_impl
+
+namespace grpc {
+class ChannelInterface;
+
+namespace internal {
+class Call;
+class CallOpSetInterface;
+class RpcMethod;
 class InterceptedChannel;
+template <class InputMessage, class OutputMessage>
+class BlockingUnaryCallImpl;
 }  // namespace internal
 
 /// Codegen interface for \a grpc::Channel.
@@ -102,30 +103,30 @@ class ChannelInterface {
 
  private:
   template <class R>
-  friend class ::grpc::ClientReader;
+  friend class ::grpc_impl::ClientReader;
   template <class W>
-  friend class ::grpc::ClientWriter;
+  friend class ::grpc_impl::ClientWriter;
   template <class W, class R>
-  friend class ::grpc::ClientReaderWriter;
+  friend class ::grpc_impl::ClientReaderWriter;
   template <class R>
-  friend class ::grpc::internal::ClientAsyncReaderFactory;
+  friend class ::grpc_impl::internal::ClientAsyncReaderFactory;
   template <class W>
-  friend class ::grpc::internal::ClientAsyncWriterFactory;
+  friend class ::grpc_impl::internal::ClientAsyncWriterFactory;
   template <class W, class R>
-  friend class ::grpc::internal::ClientAsyncReaderWriterFactory;
+  friend class ::grpc_impl::internal::ClientAsyncReaderWriterFactory;
   template <class R>
-  friend class ::grpc::internal::ClientAsyncResponseReaderFactory;
+  friend class ::grpc_impl::internal::ClientAsyncResponseReaderFactory;
   template <class W, class R>
-  friend class ::grpc::internal::ClientCallbackReaderWriterFactory;
+  friend class ::grpc_impl::internal::ClientCallbackReaderWriterFactory;
   template <class R>
-  friend class ::grpc::internal::ClientCallbackReaderFactory;
+  friend class ::grpc_impl::internal::ClientCallbackReaderFactory;
   template <class W>
-  friend class ::grpc::internal::ClientCallbackWriterFactory;
-  friend class ::grpc::internal::ClientCallbackUnaryFactory;
+  friend class ::grpc_impl::internal::ClientCallbackWriterFactory;
+  friend class ::grpc_impl::internal::ClientCallbackUnaryFactory;
   template <class InputMessage, class OutputMessage>
   friend class ::grpc::internal::BlockingUnaryCallImpl;
   template <class InputMessage, class OutputMessage>
-  friend class ::grpc::internal::CallbackUnaryCallImpl;
+  friend class ::grpc_impl::internal::CallbackUnaryCallImpl;
   friend class ::grpc::internal::RpcMethod;
   friend class ::grpc::internal::InterceptedChannel;
   virtual internal::Call CreateCall(const internal::RpcMethod& method,

include/grpcpp/impl/codegen/client_callback.h

@@ -19,1012 +19,37 @@
 #ifndef GRPCPP_IMPL_CODEGEN_CLIENT_CALLBACK_H
 #define GRPCPP_IMPL_CODEGEN_CLIENT_CALLBACK_H
 
-#include <atomic>
-#include <functional>
-
-#include <grpcpp/impl/codegen/call.h>
-#include <grpcpp/impl/codegen/call_op_set.h>
-#include <grpcpp/impl/codegen/callback_common.h>
-#include <grpcpp/impl/codegen/channel_interface.h>
-#include <grpcpp/impl/codegen/config.h>
-#include <grpcpp/impl/codegen/core_codegen_interface.h>
-#include <grpcpp/impl/codegen/status.h>
-
-namespace grpc_impl {
-class Channel;
-class ClientContext;
-}  // namespace grpc_impl
+#include <grpcpp/impl/codegen/client_callback_impl.h>
 
 namespace grpc {
-
-namespace internal {
-class RpcMethod;
-
-/// Perform a callback-based unary call
-/// TODO(vjpai): Combine as much as possible with the blocking unary call code
-template <class InputMessage, class OutputMessage>
-void CallbackUnaryCall(ChannelInterface* channel, const RpcMethod& method,
-                       ::grpc_impl::ClientContext* context,
-                       const InputMessage* request, OutputMessage* result,
-                       std::function<void(Status)> on_completion) {
-  CallbackUnaryCallImpl<InputMessage, OutputMessage> x(
-      channel, method, context, request, result, on_completion);
-}
-
-template <class InputMessage, class OutputMessage>
-class CallbackUnaryCallImpl {
- public:
-  CallbackUnaryCallImpl(ChannelInterface* channel, const RpcMethod& method,
-                        ::grpc_impl::ClientContext* context,
-                        const InputMessage* request, OutputMessage* result,
-                        std::function<void(Status)> on_completion) {
-    CompletionQueue* cq = channel->CallbackCQ();
-    GPR_CODEGEN_ASSERT(cq != nullptr);
-    Call call(channel->CreateCall(method, context, cq));
-
-    using FullCallOpSet =
-        CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
-                  CallOpRecvInitialMetadata, CallOpRecvMessage<OutputMessage>,
-                  CallOpClientSendClose, CallOpClientRecvStatus>;
-
-    auto* ops = new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(FullCallOpSet))) FullCallOpSet;
-
-    auto* tag = new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(CallbackWithStatusTag)))
-        CallbackWithStatusTag(call.call(), on_completion, ops);
-
-    // TODO(vjpai): Unify code with sync API as much as possible
-    Status s = ops->SendMessagePtr(request);
-    if (!s.ok()) {
-      tag->force_run(s);
-      return;
-    }
-    ops->SendInitialMetadata(&context->send_initial_metadata_,
-                             context->initial_metadata_flags());
-    ops->RecvInitialMetadata(context);
-    ops->RecvMessage(result);
-    ops->AllowNoMessage();
-    ops->ClientSendClose();
-    ops->ClientRecvStatus(context, tag->status_ptr());
-    ops->set_core_cq_tag(tag);
-    call.PerformOps(ops);
-  }
-};
-}  // namespace internal
-
 namespace experimental {
 
-// Forward declarations
-template <class Request, class Response>
-class ClientBidiReactor;
 template <class Response>
-class ClientReadReactor;
-template <class Request>
-class ClientWriteReactor;
-class ClientUnaryReactor;
-
-// NOTE: The streaming objects are not actually implemented in the public API.
-//       These interfaces are provided for mocking only. Typical applications
-//       will interact exclusively with the reactors that they define.
-template <class Request, class Response>
-class ClientCallbackReaderWriter {
- public:
-  virtual ~ClientCallbackReaderWriter() {}
-  virtual void StartCall() = 0;
-  virtual void Write(const Request* req, WriteOptions options) = 0;
-  virtual void WritesDone() = 0;
-  virtual void Read(Response* resp) = 0;
-  virtual void AddHold(int holds) = 0;
-  virtual void RemoveHold() = 0;
-
- protected:
-  void BindReactor(ClientBidiReactor<Request, Response>* reactor) {
-    reactor->BindStream(this);
-  }
-};
-
-template <class Response>
-class ClientCallbackReader {
- public:
-  virtual ~ClientCallbackReader() {}
-  virtual void StartCall() = 0;
-  virtual void Read(Response* resp) = 0;
-  virtual void AddHold(int holds) = 0;
-  virtual void RemoveHold() = 0;
-
- protected:
-  void BindReactor(ClientReadReactor<Response>* reactor) {
-    reactor->BindReader(this);
-  }
-};
+using ClientCallbackReader =
+    ::grpc_impl::experimental::ClientCallbackReader<Response>;
 
 template <class Request>
-class ClientCallbackWriter {
- public:
-  virtual ~ClientCallbackWriter() {}
-  virtual void StartCall() = 0;
-  void Write(const Request* req) { Write(req, WriteOptions()); }
-  virtual void Write(const Request* req, WriteOptions options) = 0;
-  void WriteLast(const Request* req, WriteOptions options) {
-    Write(req, options.set_last_message());
-  }
-  virtual void WritesDone() = 0;
+using ClientCallbackWriter =
+    ::grpc_impl::experimental::ClientCallbackWriter<Request>;
 
-  virtual void AddHold(int holds) = 0;
-  virtual void RemoveHold() = 0;
-
- protected:
-  void BindReactor(ClientWriteReactor<Request>* reactor) {
-    reactor->BindWriter(this);
-  }
-};
-
-class ClientCallbackUnary {
- public:
-  virtual ~ClientCallbackUnary() {}
-  virtual void StartCall() = 0;
-
- protected:
-  void BindReactor(ClientUnaryReactor* reactor);
-};
-
-// The following classes are the reactor interfaces that are to be implemented
-// by the user. They are passed in to the library as an argument to a call on a
-// stub (either a codegen-ed call or a generic call). The streaming RPC is
-// activated by calling StartCall, possibly after initiating StartRead,
-// StartWrite, or AddHold operations on the streaming object. Note that none of
-// the classes are pure; all reactions have a default empty reaction so that the
-// user class only needs to override those classes that it cares about.
-// The reactor must be passed to the stub invocation before any of the below
-// operations can be called.
-
-/// \a ClientBidiReactor is the interface for a bidirectional streaming RPC.
 template <class Request, class Response>
-class ClientBidiReactor {
- public:
-  virtual ~ClientBidiReactor() {}
-
-  /// Activate the RPC and initiate any reads or writes that have been Start'ed
-  /// before this call. All streaming RPCs issued by the client MUST have
-  /// StartCall invoked on them (even if they are canceled) as this call is the
-  /// activation of their lifecycle.
-  void StartCall() { stream_->StartCall(); }
-
-  /// Initiate a read operation (or post it for later initiation if StartCall
-  /// has not yet been invoked).
-  ///
-  /// \param[out] resp Where to eventually store the read message. Valid when
-  ///                  the library calls OnReadDone
-  void StartRead(Response* resp) { stream_->Read(resp); }
-
-  /// Initiate a write operation (or post it for later initiation if StartCall
-  /// has not yet been invoked).
-  ///
-  /// \param[in] req The message to be written. The library takes temporary
-  ///                ownership until OnWriteDone, at which point the application
-  ///                regains ownership of msg.
-  void StartWrite(const Request* req) { StartWrite(req, WriteOptions()); }
-
-  /// Initiate/post a write operation with specified options.
-  ///
-  /// \param[in] req The message to be written. The library takes temporary
-  ///                ownership until OnWriteDone, at which point the application
-  ///                regains ownership of msg.
-  /// \param[in] options The WriteOptions to use for writing this message
-  void StartWrite(const Request* req, WriteOptions options) {
-    stream_->Write(req, std::move(options));
-  }
-
-  /// Initiate/post a write operation with specified options and an indication
-  /// that this is the last write (like StartWrite and StartWritesDone, merged).
-  /// Note that calling this means that no more calls to StartWrite,
-  /// StartWriteLast, or StartWritesDone are allowed.
-  ///
-  /// \param[in] req The message to be written. The library takes temporary
-  ///                ownership until OnWriteDone, at which point the application
-  ///                regains ownership of msg.
-  /// \param[in] options The WriteOptions to use for writing this message
-  void StartWriteLast(const Request* req, WriteOptions options) {
-    StartWrite(req, std::move(options.set_last_message()));
-  }
-
-  /// Indicate that the RPC will have no more write operations. This can only be
-  /// issued once for a given RPC. This is not required or allowed if
-  /// StartWriteLast is used since that already has the same implication.
-  /// Note that calling this means that no more calls to StartWrite,
-  /// StartWriteLast, or StartWritesDone are allowed.
-  void StartWritesDone() { stream_->WritesDone(); }
-
-  /// Holds are needed if (and only if) this stream has operations that take
-  /// place on it after StartCall but from outside one of the reactions
-  /// (OnReadDone, etc). This is _not_ a common use of the streaming API.
-  ///
-  /// Holds must be added before calling StartCall. If a stream still has a hold
-  /// in place, its resources will not be destroyed even if the status has
-  /// already come in from the wire and there are currently no active callbacks
-  /// outstanding. Similarly, the stream will not call OnDone if there are still
-  /// holds on it.
-  ///
-  /// For example, if a StartRead or StartWrite operation is going to be
-  /// initiated from elsewhere in the application, the application should call
-  /// AddHold or AddMultipleHolds before StartCall.  If there is going to be,
-  /// for example, a read-flow and a write-flow taking place outside the
-  /// reactions, then call AddMultipleHolds(2) before StartCall. When the
-  /// application knows that it won't issue any more read operations (such as
-  /// when a read comes back as not ok), it should issue a RemoveHold(). It
-  /// should also call RemoveHold() again after it does StartWriteLast or
-  /// StartWritesDone that indicates that there will be no more write ops.
-  /// The number of RemoveHold calls must match the total number of AddHold
-  /// calls plus the number of holds added by AddMultipleHolds.
-  void AddHold() { AddMultipleHolds(1); }
-  void AddMultipleHolds(int holds) { stream_->AddHold(holds); }
-  void RemoveHold() { stream_->RemoveHold(); }
-
-  /// Notifies the application that all operations associated with this RPC
-  /// have completed and provides the RPC status outcome.
-  ///
-  /// \param[in] s The status outcome of this RPC
-  virtual void OnDone(const Status& s) {}
-
-  /// Notifies the application that a read of initial metadata from the
-  /// server is done. If the application chooses not to implement this method,
-  /// it can assume that the initial metadata has been read before the first
-  /// call of OnReadDone or OnDone.
-  ///
-  /// \param[in] ok Was the initial metadata read successfully? If false, no
-  ///               further read-side operation will succeed.
-  virtual void OnReadInitialMetadataDone(bool ok) {}
-
-  /// Notifies the application that a StartRead operation completed.
-  ///
-  /// \param[in] ok Was it successful? If false, no further read-side operation
-  ///               will succeed.
-  virtual void OnReadDone(bool ok) {}
-
-  /// Notifies the application that a StartWrite operation completed.
-  ///
-  /// \param[in] ok Was it successful? If false, no further write-side operation
-  ///               will succeed.
-  virtual void OnWriteDone(bool ok) {}
-
-  /// Notifies the application that a StartWritesDone operation completed. Note
-  /// that this is only used on explicit StartWritesDone operations and not for
-  /// those that are implicitly invoked as part of a StartWriteLast.
-  ///
-  /// \param[in] ok Was it successful? If false, the application will later see
-  ///               the failure reflected as a bad status in OnDone.
-  virtual void OnWritesDoneDone(bool ok) {}
+using ClientCallbackReaderWriter =
+    ::grpc_impl::experimental::ClientCallbackReaderWriter<Request, Response>;
 
- private:
-  friend class ClientCallbackReaderWriter<Request, Response>;
-  void BindStream(ClientCallbackReaderWriter<Request, Response>* stream) {
-    stream_ = stream;
-  }
-  ClientCallbackReaderWriter<Request, Response>* stream_;
-};
-
-/// \a ClientReadReactor is the interface for a server-streaming RPC.
-/// All public methods behave as in ClientBidiReactor.
 template <class Response>
-class ClientReadReactor {
- public:
-  virtual ~ClientReadReactor() {}
-
-  void StartCall() { reader_->StartCall(); }
-  void StartRead(Response* resp) { reader_->Read(resp); }
-
-  void AddHold() { AddMultipleHolds(1); }
-  void AddMultipleHolds(int holds) { reader_->AddHold(holds); }
-  void RemoveHold() { reader_->RemoveHold(); }
-
-  virtual void OnDone(const Status& s) {}
-  virtual void OnReadInitialMetadataDone(bool ok) {}
-  virtual void OnReadDone(bool ok) {}
-
- private:
-  friend class ClientCallbackReader<Response>;
-  void BindReader(ClientCallbackReader<Response>* reader) { reader_ = reader; }
-  ClientCallbackReader<Response>* reader_;
-};
+using ClientReadReactor =
+    ::grpc_impl::experimental::ClientReadReactor<Response>;
 
-/// \a ClientWriteReactor is the interface for a client-streaming RPC.
-/// All public methods behave as in ClientBidiReactor.
 template <class Request>
-class ClientWriteReactor {
- public:
-  virtual ~ClientWriteReactor() {}
-
-  void StartCall() { writer_->StartCall(); }
-  void StartWrite(const Request* req) { StartWrite(req, WriteOptions()); }
-  void StartWrite(const Request* req, WriteOptions options) {
-    writer_->Write(req, std::move(options));
-  }
-  void StartWriteLast(const Request* req, WriteOptions options) {
-    StartWrite(req, std::move(options.set_last_message()));
-  }
-  void StartWritesDone() { writer_->WritesDone(); }
-
-  void AddHold() { AddMultipleHolds(1); }
-  void AddMultipleHolds(int holds) { writer_->AddHold(holds); }
-  void RemoveHold() { writer_->RemoveHold(); }
-
-  virtual void OnDone(const Status& s) {}
-  virtual void OnReadInitialMetadataDone(bool ok) {}
-  virtual void OnWriteDone(bool ok) {}
-  virtual void OnWritesDoneDone(bool ok) {}
-
- private:
-  friend class ClientCallbackWriter<Request>;
-  void BindWriter(ClientCallbackWriter<Request>* writer) { writer_ = writer; }
-  ClientCallbackWriter<Request>* writer_;
-};
-
-/// \a ClientUnaryReactor is a reactor-style interface for a unary RPC.
-/// This is _not_ a common way of invoking a unary RPC. In practice, this
-/// option should be used only if the unary RPC wants to receive initial
-/// metadata without waiting for the response to complete. Most deployments of
-/// RPC systems do not use this option, but it is needed for generality.
-/// All public methods behave as in ClientBidiReactor.
-/// StartCall is included for consistency with the other reactor flavors: even
-/// though there are no StartRead or StartWrite operations to queue before the
-/// call (that is part of the unary call itself) and there is no reactor object
-/// being created as a result of this call, we keep a consistent 2-phase
-/// initiation API among all the reactor flavors.
-class ClientUnaryReactor {
- public:
-  virtual ~ClientUnaryReactor() {}
-
-  void StartCall() { call_->StartCall(); }
-  virtual void OnDone(const Status& s) {}
-  virtual void OnReadInitialMetadataDone(bool ok) {}
-
- private:
-  friend class ClientCallbackUnary;
-  void BindCall(ClientCallbackUnary* call) { call_ = call; }
-  ClientCallbackUnary* call_;
-};
-
-// Define function out-of-line from class to avoid forward declaration issue
-inline void ClientCallbackUnary::BindReactor(ClientUnaryReactor* reactor) {
-  reactor->BindCall(this);
-}
-
-}  // namespace experimental
-
-namespace internal {
-
-// Forward declare factory classes for friendship
-template <class Request, class Response>
-class ClientCallbackReaderWriterFactory;
-template <class Response>
-class ClientCallbackReaderFactory;
-template <class Request>
-class ClientCallbackWriterFactory;
-
-template <class Request, class Response>
-class ClientCallbackReaderWriterImpl
-    : public ::grpc::experimental::ClientCallbackReaderWriter<Request,
-                                                              Response> {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientCallbackReaderWriterImpl));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void MaybeFinish() {
-    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                         1, std::memory_order_acq_rel) == 1)) {
-      Status s = std::move(finish_status_);
-      auto* reactor = reactor_;
-      auto* call = call_.call();
-      this->~ClientCallbackReaderWriterImpl();
-      g_core_codegen_interface->grpc_call_unref(call);
-      reactor->OnDone(s);
-    }
-  }
-
-  void StartCall() override {
-    // This call initiates two batches, plus any backlog, each with a callback
-    // 1. Send initial metadata (unless corked) + recv initial metadata
-    // 2. Any read backlog
-    // 3. Any write backlog
-    // 4. Recv trailing metadata, on_completion callback
-    started_ = true;
-
-    start_tag_.Set(call_.call(),
-                   [this](bool ok) {
-                     reactor_->OnReadInitialMetadataDone(ok);
-                     MaybeFinish();
-                   },
-                   &start_ops_);
-    if (!start_corked_) {
-      start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                     context_->initial_metadata_flags());
-    }
-    start_ops_.RecvInitialMetadata(context_);
-    start_ops_.set_core_cq_tag(&start_tag_);
-    call_.PerformOps(&start_ops_);
-
-    // Also set up the read and write tags so that they don't have to be set up
-    // each time
-    write_tag_.Set(call_.call(),
-                   [this](bool ok) {
-                     reactor_->OnWriteDone(ok);
-                     MaybeFinish();
-                   },
-                   &write_ops_);
-    write_ops_.set_core_cq_tag(&write_tag_);
-
-    read_tag_.Set(call_.call(),
-                  [this](bool ok) {
-                    reactor_->OnReadDone(ok);
-                    MaybeFinish();
-                  },
-                  &read_ops_);
-    read_ops_.set_core_cq_tag(&read_tag_);
-    if (read_ops_at_start_) {
-      call_.PerformOps(&read_ops_);
-    }
-
-    if (write_ops_at_start_) {
-      call_.PerformOps(&write_ops_);
-    }
-
-    if (writes_done_ops_at_start_) {
-      call_.PerformOps(&writes_done_ops_);
-    }
-
-    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
-                    &finish_ops_);
-    finish_ops_.ClientRecvStatus(context_, &finish_status_);
-    finish_ops_.set_core_cq_tag(&finish_tag_);
-    call_.PerformOps(&finish_ops_);
-  }
-
-  void Read(Response* msg) override {
-    read_ops_.RecvMessage(msg);
-    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-    if (started_) {
-      call_.PerformOps(&read_ops_);
-    } else {
-      read_ops_at_start_ = true;
-    }
-  }
-
-  void Write(const Request* msg, WriteOptions options) override {
-    if (start_corked_) {
-      write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                     context_->initial_metadata_flags());
-      start_corked_ = false;
-    }
-
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-      write_ops_.ClientSendClose();
-    }
-    // TODO(vjpai): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(msg, options).ok());
-    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-    if (started_) {
-      call_.PerformOps(&write_ops_);
-    } else {
-      write_ops_at_start_ = true;
-    }
-  }
-  void WritesDone() override {
-    if (start_corked_) {
-      writes_done_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                           context_->initial_metadata_flags());
-      start_corked_ = false;
-    }
-    writes_done_ops_.ClientSendClose();
-    writes_done_tag_.Set(call_.call(),
-                         [this](bool ok) {
-                           reactor_->OnWritesDoneDone(ok);
-                           MaybeFinish();
-                         },
-                         &writes_done_ops_);
-    writes_done_ops_.set_core_cq_tag(&writes_done_tag_);
-    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-    if (started_) {
-      call_.PerformOps(&writes_done_ops_);
-    } else {
-      writes_done_ops_at_start_ = true;
-    }
-  }
-
-  void AddHold(int holds) override {
-    callbacks_outstanding_.fetch_add(holds, std::memory_order_relaxed);
-  }
-  void RemoveHold() override { MaybeFinish(); }
-
- private:
-  friend class ClientCallbackReaderWriterFactory<Request, Response>;
-
-  ClientCallbackReaderWriterImpl(
-      Call call, ::grpc_impl::ClientContext* context,
-      ::grpc::experimental::ClientBidiReactor<Request, Response>* reactor)
-      : context_(context),
-        call_(call),
-        reactor_(reactor),
-        start_corked_(context_->initial_metadata_corked_) {
-    this->BindReactor(reactor);
-  }
-
-  ::grpc_impl::ClientContext* const context_;
-  Call call_;
-  ::grpc::experimental::ClientBidiReactor<Request, Response>* const reactor_;
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpRecvInitialMetadata> start_ops_;
-  CallbackWithSuccessTag start_tag_;
-  bool start_corked_;
-
-  CallOpSet<CallOpClientRecvStatus> finish_ops_;
-  CallbackWithSuccessTag finish_tag_;
-  Status finish_status_;
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, CallOpClientSendClose>
-      write_ops_;
-  CallbackWithSuccessTag write_tag_;
-  bool write_ops_at_start_{false};
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpClientSendClose> writes_done_ops_;
-  CallbackWithSuccessTag writes_done_tag_;
-  bool writes_done_ops_at_start_{false};
-
-  CallOpSet<CallOpRecvMessage<Response>> read_ops_;
-  CallbackWithSuccessTag read_tag_;
-  bool read_ops_at_start_{false};
-
-  // Minimum of 2 callbacks to pre-register for start and finish
-  std::atomic<intptr_t> callbacks_outstanding_{2};
-  bool started_{false};
-};
+using ClientWriteReactor =
+    ::grpc_impl::experimental::ClientWriteReactor<Request>;
 
 template <class Request, class Response>
-class ClientCallbackReaderWriterFactory {
- public:
-  static void Create(
-      ChannelInterface* channel, const ::grpc::internal::RpcMethod& method,
-      ::grpc_impl::ClientContext* context,
-      ::grpc::experimental::ClientBidiReactor<Request, Response>* reactor) {
-    Call call = channel->CreateCall(method, context, channel->CallbackCQ());
-
-    g_core_codegen_interface->grpc_call_ref(call.call());
-    new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientCallbackReaderWriterImpl<Request, Response>)))
-        ClientCallbackReaderWriterImpl<Request, Response>(call, context,
-                                                          reactor);
-  }
-};
-
-template <class Response>
-class ClientCallbackReaderImpl
-    : public ::grpc::experimental::ClientCallbackReader<Response> {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientCallbackReaderImpl));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void MaybeFinish() {
-    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                         1, std::memory_order_acq_rel) == 1)) {
-      Status s = std::move(finish_status_);
-      auto* reactor = reactor_;
-      auto* call = call_.call();
-      this->~ClientCallbackReaderImpl();
-      g_core_codegen_interface->grpc_call_unref(call);
-      reactor->OnDone(s);
-    }
-  }
-
-  void StartCall() override {
-    // This call initiates two batches, plus any backlog, each with a callback
-    // 1. Send initial metadata (unless corked) + recv initial metadata
-    // 2. Any backlog
-    // 3. Recv trailing metadata, on_completion callback
-    started_ = true;
-
-    start_tag_.Set(call_.call(),
-                   [this](bool ok) {
-                     reactor_->OnReadInitialMetadataDone(ok);
-                     MaybeFinish();
-                   },
-                   &start_ops_);
-    start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                   context_->initial_metadata_flags());
-    start_ops_.RecvInitialMetadata(context_);
-    start_ops_.set_core_cq_tag(&start_tag_);
-    call_.PerformOps(&start_ops_);
-
-    // Also set up the read tag so it doesn't have to be set up each time
-    read_tag_.Set(call_.call(),
-                  [this](bool ok) {
-                    reactor_->OnReadDone(ok);
-                    MaybeFinish();
-                  },
-                  &read_ops_);
-    read_ops_.set_core_cq_tag(&read_tag_);
-    if (read_ops_at_start_) {
-      call_.PerformOps(&read_ops_);
-    }
-
-    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
-                    &finish_ops_);
-    finish_ops_.ClientRecvStatus(context_, &finish_status_);
-    finish_ops_.set_core_cq_tag(&finish_tag_);
-    call_.PerformOps(&finish_ops_);
-  }
-
-  void Read(Response* msg) override {
-    read_ops_.RecvMessage(msg);
-    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-    if (started_) {
-      call_.PerformOps(&read_ops_);
-    } else {
-      read_ops_at_start_ = true;
-    }
-  }
-
-  void AddHold(int holds) override {
-    callbacks_outstanding_.fetch_add(holds, std::memory_order_relaxed);
-  }
-  void RemoveHold() override { MaybeFinish(); }
-
- private:
-  friend class ClientCallbackReaderFactory<Response>;
-
-  template <class Request>
-  ClientCallbackReaderImpl(
-      Call call, ::grpc_impl::ClientContext* context, Request* request,
-      ::grpc::experimental::ClientReadReactor<Response>* reactor)
-      : context_(context), call_(call), reactor_(reactor) {
-    this->BindReactor(reactor);
-    // TODO(vjpai): don't assert
-    GPR_CODEGEN_ASSERT(start_ops_.SendMessagePtr(request).ok());
-    start_ops_.ClientSendClose();
-  }
-
-  ::grpc_impl::ClientContext* const context_;
-  Call call_;
-  ::grpc::experimental::ClientReadReactor<Response>* const reactor_;
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, CallOpClientSendClose,
-            CallOpRecvInitialMetadata>
-      start_ops_;
-  CallbackWithSuccessTag start_tag_;
-
-  CallOpSet<CallOpClientRecvStatus> finish_ops_;
-  CallbackWithSuccessTag finish_tag_;
-  Status finish_status_;
-
-  CallOpSet<CallOpRecvMessage<Response>> read_ops_;
-  CallbackWithSuccessTag read_tag_;
-  bool read_ops_at_start_{false};
-
-  // Minimum of 2 callbacks to pre-register for start and finish
-  std::atomic<intptr_t> callbacks_outstanding_{2};
-  bool started_{false};
-};
-
-template <class Response>
-class ClientCallbackReaderFactory {
- public:
-  template <class Request>
-  static void Create(
-      ChannelInterface* channel, const ::grpc::internal::RpcMethod& method,
-      ::grpc_impl::ClientContext* context, const Request* request,
-      ::grpc::experimental::ClientReadReactor<Response>* reactor) {
-    Call call = channel->CreateCall(method, context, channel->CallbackCQ());
-
-    g_core_codegen_interface->grpc_call_ref(call.call());
-    new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientCallbackReaderImpl<Response>)))
-        ClientCallbackReaderImpl<Response>(call, context, request, reactor);
-  }
-};
-
-template <class Request>
-class ClientCallbackWriterImpl
-    : public ::grpc::experimental::ClientCallbackWriter<Request> {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientCallbackWriterImpl));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void MaybeFinish() {
-    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                         1, std::memory_order_acq_rel) == 1)) {
-      Status s = std::move(finish_status_);
-      auto* reactor = reactor_;
-      auto* call = call_.call();
-      this->~ClientCallbackWriterImpl();
-      g_core_codegen_interface->grpc_call_unref(call);
-      reactor->OnDone(s);
-    }
-  }
-
-  void StartCall() override {
-    // This call initiates two batches, plus any backlog, each with a callback
-    // 1. Send initial metadata (unless corked) + recv initial metadata
-    // 2. Any backlog
-    // 3. Recv trailing metadata, on_completion callback
-    started_ = true;
+using ClientBidiReactor =
+    ::grpc_impl::experimental::ClientBidiReactor<Request, Response>;
 
-    start_tag_.Set(call_.call(),
-                   [this](bool ok) {
-                     reactor_->OnReadInitialMetadataDone(ok);
-                     MaybeFinish();
-                   },
-                   &start_ops_);
-    if (!start_corked_) {
-      start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                     context_->initial_metadata_flags());
-    }
-    start_ops_.RecvInitialMetadata(context_);
-    start_ops_.set_core_cq_tag(&start_tag_);
-    call_.PerformOps(&start_ops_);
-
-    // Also set up the read and write tags so that they don't have to be set up
-    // each time
-    write_tag_.Set(call_.call(),
-                   [this](bool ok) {
-                     reactor_->OnWriteDone(ok);
-                     MaybeFinish();
-                   },
-                   &write_ops_);
-    write_ops_.set_core_cq_tag(&write_tag_);
-
-    if (write_ops_at_start_) {
-      call_.PerformOps(&write_ops_);
-    }
-
-    if (writes_done_ops_at_start_) {
-      call_.PerformOps(&writes_done_ops_);
-    }
-
-    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
-                    &finish_ops_);
-    finish_ops_.ClientRecvStatus(context_, &finish_status_);
-    finish_ops_.set_core_cq_tag(&finish_tag_);
-    call_.PerformOps(&finish_ops_);
-  }
-
-  void Write(const Request* msg, WriteOptions options) override {
-    if (start_corked_) {
-      write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                     context_->initial_metadata_flags());
-      start_corked_ = false;
-    }
-
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-      write_ops_.ClientSendClose();
-    }
-    // TODO(vjpai): don't assert
-    GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(msg, options).ok());
-    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-    if (started_) {
-      call_.PerformOps(&write_ops_);
-    } else {
-      write_ops_at_start_ = true;
-    }
-  }
-  void WritesDone() override {
-    if (start_corked_) {
-      writes_done_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                           context_->initial_metadata_flags());
-      start_corked_ = false;
-    }
-    writes_done_ops_.ClientSendClose();
-    writes_done_tag_.Set(call_.call(),
-                         [this](bool ok) {
-                           reactor_->OnWritesDoneDone(ok);
-                           MaybeFinish();
-                         },
-                         &writes_done_ops_);
-    writes_done_ops_.set_core_cq_tag(&writes_done_tag_);
-    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-    if (started_) {
-      call_.PerformOps(&writes_done_ops_);
-    } else {
-      writes_done_ops_at_start_ = true;
-    }
-  }
-
-  void AddHold(int holds) override {
-    callbacks_outstanding_.fetch_add(holds, std::memory_order_relaxed);
-  }
-  void RemoveHold() override { MaybeFinish(); }
-
- private:
-  friend class ClientCallbackWriterFactory<Request>;
-
-  template <class Response>
-  ClientCallbackWriterImpl(
-      Call call, ::grpc_impl::ClientContext* context, Response* response,
-      ::grpc::experimental::ClientWriteReactor<Request>* reactor)
-      : context_(context),
-        call_(call),
-        reactor_(reactor),
-        start_corked_(context_->initial_metadata_corked_) {
-    this->BindReactor(reactor);
-    finish_ops_.RecvMessage(response);
-    finish_ops_.AllowNoMessage();
-  }
-
-  ::grpc_impl::ClientContext* const context_;
-  Call call_;
-  ::grpc::experimental::ClientWriteReactor<Request>* const reactor_;
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpRecvInitialMetadata> start_ops_;
-  CallbackWithSuccessTag start_tag_;
-  bool start_corked_;
-
-  CallOpSet<CallOpGenericRecvMessage, CallOpClientRecvStatus> finish_ops_;
-  CallbackWithSuccessTag finish_tag_;
-  Status finish_status_;
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, CallOpClientSendClose>
-      write_ops_;
-  CallbackWithSuccessTag write_tag_;
-  bool write_ops_at_start_{false};
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpClientSendClose> writes_done_ops_;
-  CallbackWithSuccessTag writes_done_tag_;
-  bool writes_done_ops_at_start_{false};
-
-  // Minimum of 2 callbacks to pre-register for start and finish
-  std::atomic<intptr_t> callbacks_outstanding_{2};
-  bool started_{false};
-};
-
-template <class Request>
-class ClientCallbackWriterFactory {
- public:
-  template <class Response>
-  static void Create(
-      ChannelInterface* channel, const ::grpc::internal::RpcMethod& method,
-      ::grpc_impl::ClientContext* context, Response* response,
-      ::grpc::experimental::ClientWriteReactor<Request>* reactor) {
-    Call call = channel->CreateCall(method, context, channel->CallbackCQ());
-
-    g_core_codegen_interface->grpc_call_ref(call.call());
-    new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientCallbackWriterImpl<Request>)))
-        ClientCallbackWriterImpl<Request>(call, context, response, reactor);
-  }
-};
-
-class ClientCallbackUnaryImpl final
-    : public ::grpc::experimental::ClientCallbackUnary {
- public:
-  // always allocated against a call arena, no memory free required
-  static void operator delete(void* ptr, std::size_t size) {
-    assert(size == sizeof(ClientCallbackUnaryImpl));
-  }
-
-  // This operator should never be called as the memory should be freed as part
-  // of the arena destruction. It only exists to provide a matching operator
-  // delete to the operator new so that some compilers will not complain (see
-  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
-  // there are no tests catching the compiler warning.
-  static void operator delete(void*, void*) { assert(0); }
-
-  void StartCall() override {
-    // This call initiates two batches, each with a callback
-    // 1. Send initial metadata + write + writes done + recv initial metadata
-    // 2. Read message, recv trailing metadata
-    started_ = true;
-
-    start_tag_.Set(call_.call(),
-                   [this](bool ok) {
-                     reactor_->OnReadInitialMetadataDone(ok);
-                     MaybeFinish();
-                   },
-                   &start_ops_);
-    start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
-                                   context_->initial_metadata_flags());
-    start_ops_.RecvInitialMetadata(context_);
-    start_ops_.set_core_cq_tag(&start_tag_);
-    call_.PerformOps(&start_ops_);
-
-    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
-                    &finish_ops_);
-    finish_ops_.ClientRecvStatus(context_, &finish_status_);
-    finish_ops_.set_core_cq_tag(&finish_tag_);
-    call_.PerformOps(&finish_ops_);
-  }
-
-  void MaybeFinish() {
-    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                         1, std::memory_order_acq_rel) == 1)) {
-      Status s = std::move(finish_status_);
-      auto* reactor = reactor_;
-      auto* call = call_.call();
-      this->~ClientCallbackUnaryImpl();
-      g_core_codegen_interface->grpc_call_unref(call);
-      reactor->OnDone(s);
-    }
-  }
-
- private:
-  friend class ClientCallbackUnaryFactory;
-
-  template <class Request, class Response>
-  ClientCallbackUnaryImpl(Call call, ::grpc_impl::ClientContext* context,
-                          Request* request, Response* response,
-                          ::grpc::experimental::ClientUnaryReactor* reactor)
-      : context_(context), call_(call), reactor_(reactor) {
-    this->BindReactor(reactor);
-    // TODO(vjpai): don't assert
-    GPR_CODEGEN_ASSERT(start_ops_.SendMessagePtr(request).ok());
-    start_ops_.ClientSendClose();
-    finish_ops_.RecvMessage(response);
-    finish_ops_.AllowNoMessage();
-  }
-
-  ::grpc_impl::ClientContext* const context_;
-  Call call_;
-  ::grpc::experimental::ClientUnaryReactor* const reactor_;
-
-  CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, CallOpClientSendClose,
-            CallOpRecvInitialMetadata>
-      start_ops_;
-  CallbackWithSuccessTag start_tag_;
-
-  CallOpSet<CallOpGenericRecvMessage, CallOpClientRecvStatus> finish_ops_;
-  CallbackWithSuccessTag finish_tag_;
-  Status finish_status_;
-
-  // This call will have 2 callbacks: start and finish
-  std::atomic<intptr_t> callbacks_outstanding_{2};
-  bool started_{false};
-};
-
-class ClientCallbackUnaryFactory {
- public:
-  template <class Request, class Response>
-  static void Create(ChannelInterface* channel,
-                     const ::grpc::internal::RpcMethod& method,
-                     ::grpc_impl::ClientContext* context,
-                     const Request* request, Response* response,
-                     ::grpc::experimental::ClientUnaryReactor* reactor) {
-    Call call = channel->CreateCall(method, context, channel->CallbackCQ());
-
-    g_core_codegen_interface->grpc_call_ref(call.call());
-
-    new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call.call(), sizeof(ClientCallbackUnaryImpl)))
-        ClientCallbackUnaryImpl(call, context, request, response, reactor);
-  }
-};
-
-}  // namespace internal
+typedef ::grpc_impl::experimental::ClientUnaryReactor ClientUnaryReactor;
+}  // namespace experimental
 }  // namespace grpc
 
 #endif  // GRPCPP_IMPL_CODEGEN_CLIENT_CALLBACK_H

include/grpcpp/impl/codegen/client_callback_impl.h

@@ -0,0 +1,1067 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_CLIENT_CALLBACK_IMPL_H
+#define GRPCPP_IMPL_CODEGEN_CLIENT_CALLBACK_IMPL_H
+#include <atomic>
+#include <functional>
+
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/call_op_set.h>
+#include <grpcpp/impl/codegen/callback_common.h>
+#include <grpcpp/impl/codegen/channel_interface.h>
+#include <grpcpp/impl/codegen/config.h>
+#include <grpcpp/impl/codegen/core_codegen_interface.h>
+#include <grpcpp/impl/codegen/status.h>
+
+namespace grpc {
+namespace internal {
+class RpcMethod;
+}  // namespace internal
+}  // namespace grpc
+
+namespace grpc_impl {
+class Channel;
+class ClientContext;
+
+namespace internal {
+
+/// Perform a callback-based unary call
+/// TODO(vjpai): Combine as much as possible with the blocking unary call code
+template <class InputMessage, class OutputMessage>
+void CallbackUnaryCall(::grpc::ChannelInterface* channel,
+                       const ::grpc::internal::RpcMethod& method,
+                       ::grpc_impl::ClientContext* context,
+                       const InputMessage* request, OutputMessage* result,
+                       std::function<void(::grpc::Status)> on_completion) {
+  CallbackUnaryCallImpl<InputMessage, OutputMessage> x(
+      channel, method, context, request, result, on_completion);
+}
+
+template <class InputMessage, class OutputMessage>
+class CallbackUnaryCallImpl {
+ public:
+  CallbackUnaryCallImpl(::grpc::ChannelInterface* channel,
+                        const ::grpc::internal::RpcMethod& method,
+                        ::grpc_impl::ClientContext* context,
+                        const InputMessage* request, OutputMessage* result,
+                        std::function<void(::grpc::Status)> on_completion) {
+    ::grpc_impl::CompletionQueue* cq = channel->CallbackCQ();
+    GPR_CODEGEN_ASSERT(cq != nullptr);
+    grpc::internal::Call call(channel->CreateCall(method, context, cq));
+
+    using FullCallOpSet = grpc::internal::CallOpSet<
+        ::grpc::internal::CallOpSendInitialMetadata,
+        grpc::internal::CallOpSendMessage,
+        grpc::internal::CallOpRecvInitialMetadata,
+        grpc::internal::CallOpRecvMessage<OutputMessage>,
+        grpc::internal::CallOpClientSendClose,
+        grpc::internal::CallOpClientRecvStatus>;
+
+    auto* ops = new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(FullCallOpSet))) FullCallOpSet;
+
+    auto* tag = new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(grpc::internal::CallbackWithStatusTag)))
+        grpc::internal::CallbackWithStatusTag(call.call(), on_completion, ops);
+
+    // TODO(vjpai): Unify code with sync API as much as possible
+    ::grpc::Status s = ops->SendMessagePtr(request);
+    if (!s.ok()) {
+      tag->force_run(s);
+      return;
+    }
+    ops->SendInitialMetadata(&context->send_initial_metadata_,
+                             context->initial_metadata_flags());
+    ops->RecvInitialMetadata(context);
+    ops->RecvMessage(result);
+    ops->AllowNoMessage();
+    ops->ClientSendClose();
+    ops->ClientRecvStatus(context, tag->status_ptr());
+    ops->set_core_cq_tag(tag);
+    call.PerformOps(ops);
+  }
+};
+}  // namespace internal
+
+namespace experimental {
+
+// Forward declarations
+template <class Request, class Response>
+class ClientBidiReactor;
+template <class Response>
+class ClientReadReactor;
+template <class Request>
+class ClientWriteReactor;
+class ClientUnaryReactor;
+
+// NOTE: The streaming objects are not actually implemented in the public API.
+//       These interfaces are provided for mocking only. Typical applications
+//       will interact exclusively with the reactors that they define.
+template <class Request, class Response>
+class ClientCallbackReaderWriter {
+ public:
+  virtual ~ClientCallbackReaderWriter() {}
+  virtual void StartCall() = 0;
+  virtual void Write(const Request* req, ::grpc::WriteOptions options) = 0;
+  virtual void WritesDone() = 0;
+  virtual void Read(Response* resp) = 0;
+  virtual void AddHold(int holds) = 0;
+  virtual void RemoveHold() = 0;
+
+ protected:
+  void BindReactor(ClientBidiReactor<Request, Response>* reactor) {
+    reactor->BindStream(this);
+  }
+};
+
+template <class Response>
+class ClientCallbackReader {
+ public:
+  virtual ~ClientCallbackReader() {}
+  virtual void StartCall() = 0;
+  virtual void Read(Response* resp) = 0;
+  virtual void AddHold(int holds) = 0;
+  virtual void RemoveHold() = 0;
+
+ protected:
+  void BindReactor(ClientReadReactor<Response>* reactor) {
+    reactor->BindReader(this);
+  }
+};
+
+template <class Request>
+class ClientCallbackWriter {
+ public:
+  virtual ~ClientCallbackWriter() {}
+  virtual void StartCall() = 0;
+  void Write(const Request* req) { Write(req, ::grpc::WriteOptions()); }
+  virtual void Write(const Request* req, ::grpc::WriteOptions options) = 0;
+  void WriteLast(const Request* req, ::grpc::WriteOptions options) {
+    Write(req, options.set_last_message());
+  }
+  virtual void WritesDone() = 0;
+
+  virtual void AddHold(int holds) = 0;
+  virtual void RemoveHold() = 0;
+
+ protected:
+  void BindReactor(ClientWriteReactor<Request>* reactor) {
+    reactor->BindWriter(this);
+  }
+};
+
+class ClientCallbackUnary {
+ public:
+  virtual ~ClientCallbackUnary() {}
+  virtual void StartCall() = 0;
+
+ protected:
+  void BindReactor(ClientUnaryReactor* reactor);
+};
+
+// The following classes are the reactor interfaces that are to be implemented
+// by the user. They are passed in to the library as an argument to a call on a
+// stub (either a codegen-ed call or a generic call). The streaming RPC is
+// activated by calling StartCall, possibly after initiating StartRead,
+// StartWrite, or AddHold operations on the streaming object. Note that none of
+// the classes are pure; all reactions have a default empty reaction so that the
+// user class only needs to override those classes that it cares about.
+// The reactor must be passed to the stub invocation before any of the below
+// operations can be called.
+
+/// \a ClientBidiReactor is the interface for a bidirectional streaming RPC.
+template <class Request, class Response>
+class ClientBidiReactor {
+ public:
+  virtual ~ClientBidiReactor() {}
+
+  /// Activate the RPC and initiate any reads or writes that have been Start'ed
+  /// before this call. All streaming RPCs issued by the client MUST have
+  /// StartCall invoked on them (even if they are canceled) as this call is the
+  /// activation of their lifecycle.
+  void StartCall() { stream_->StartCall(); }
+
+  /// Initiate a read operation (or post it for later initiation if StartCall
+  /// has not yet been invoked).
+  ///
+  /// \param[out] resp Where to eventually store the read message. Valid when
+  ///                  the library calls OnReadDone
+  void StartRead(Response* resp) { stream_->Read(resp); }
+
+  /// Initiate a write operation (or post it for later initiation if StartCall
+  /// has not yet been invoked).
+  ///
+  /// \param[in] req The message to be written. The library takes temporary
+  ///                ownership until OnWriteDone, at which point the application
+  ///                regains ownership of msg.
+  void StartWrite(const Request* req) {
+    StartWrite(req, ::grpc::WriteOptions());
+  }
+
+  /// Initiate/post a write operation with specified options.
+  ///
+  /// \param[in] req The message to be written. The library takes temporary
+  ///                ownership until OnWriteDone, at which point the application
+  ///                regains ownership of msg.
+  /// \param[in] options The WriteOptions to use for writing this message
+  void StartWrite(const Request* req, ::grpc::WriteOptions options) {
+    stream_->Write(req, std::move(options));
+  }
+
+  /// Initiate/post a write operation with specified options and an indication
+  /// that this is the last write (like StartWrite and StartWritesDone, merged).
+  /// Note that calling this means that no more calls to StartWrite,
+  /// StartWriteLast, or StartWritesDone are allowed.
+  ///
+  /// \param[in] req The message to be written. The library takes temporary
+  ///                ownership until OnWriteDone, at which point the application
+  ///                regains ownership of msg.
+  /// \param[in] options The WriteOptions to use for writing this message
+  void StartWriteLast(const Request* req, ::grpc::WriteOptions options) {
+    StartWrite(req, std::move(options.set_last_message()));
+  }
+
+  /// Indicate that the RPC will have no more write operations. This can only be
+  /// issued once for a given RPC. This is not required or allowed if
+  /// StartWriteLast is used since that already has the same implication.
+  /// Note that calling this means that no more calls to StartWrite,
+  /// StartWriteLast, or StartWritesDone are allowed.
+  void StartWritesDone() { stream_->WritesDone(); }
+
+  /// Holds are needed if (and only if) this stream has operations that take
+  /// place on it after StartCall but from outside one of the reactions
+  /// (OnReadDone, etc). This is _not_ a common use of the streaming API.
+  ///
+  /// Holds must be added before calling StartCall. If a stream still has a hold
+  /// in place, its resources will not be destroyed even if the status has
+  /// already come in from the wire and there are currently no active callbacks
+  /// outstanding. Similarly, the stream will not call OnDone if there are still
+  /// holds on it.
+  ///
+  /// For example, if a StartRead or StartWrite operation is going to be
+  /// initiated from elsewhere in the application, the application should call
+  /// AddHold or AddMultipleHolds before StartCall.  If there is going to be,
+  /// for example, a read-flow and a write-flow taking place outside the
+  /// reactions, then call AddMultipleHolds(2) before StartCall. When the
+  /// application knows that it won't issue any more read operations (such as
+  /// when a read comes back as not ok), it should issue a RemoveHold(). It
+  /// should also call RemoveHold() again after it does StartWriteLast or
+  /// StartWritesDone that indicates that there will be no more write ops.
+  /// The number of RemoveHold calls must match the total number of AddHold
+  /// calls plus the number of holds added by AddMultipleHolds.
+  void AddHold() { AddMultipleHolds(1); }
+  void AddMultipleHolds(int holds) { stream_->AddHold(holds); }
+  void RemoveHold() { stream_->RemoveHold(); }
+
+  /// Notifies the application that all operations associated with this RPC
+  /// have completed and provides the RPC status outcome.
+  ///
+  /// \param[in] s The status outcome of this RPC
+  virtual void OnDone(const ::grpc::Status& s) {}
+
+  /// Notifies the application that a read of initial metadata from the
+  /// server is done. If the application chooses not to implement this method,
+  /// it can assume that the initial metadata has been read before the first
+  /// call of OnReadDone or OnDone.
+  ///
+  /// \param[in] ok Was the initial metadata read successfully? If false, no
+  ///               further read-side operation will succeed.
+  virtual void OnReadInitialMetadataDone(bool ok) {}
+
+  /// Notifies the application that a StartRead operation completed.
+  ///
+  /// \param[in] ok Was it successful? If false, no further read-side operation
+  ///               will succeed.
+  virtual void OnReadDone(bool ok) {}
+
+  /// Notifies the application that a StartWrite operation completed.
+  ///
+  /// \param[in] ok Was it successful? If false, no further write-side operation
+  ///               will succeed.
+  virtual void OnWriteDone(bool ok) {}
+
+  /// Notifies the application that a StartWritesDone operation completed. Note
+  /// that this is only used on explicit StartWritesDone operations and not for
+  /// those that are implicitly invoked as part of a StartWriteLast.
+  ///
+  /// \param[in] ok Was it successful? If false, the application will later see
+  ///               the failure reflected as a bad status in OnDone.
+  virtual void OnWritesDoneDone(bool ok) {}
+
+ private:
+  friend class ClientCallbackReaderWriter<Request, Response>;
+  void BindStream(ClientCallbackReaderWriter<Request, Response>* stream) {
+    stream_ = stream;
+  }
+  ClientCallbackReaderWriter<Request, Response>* stream_;
+};
+
+/// \a ClientReadReactor is the interface for a server-streaming RPC.
+/// All public methods behave as in ClientBidiReactor.
+template <class Response>
+class ClientReadReactor {
+ public:
+  virtual ~ClientReadReactor() {}
+
+  void StartCall() { reader_->StartCall(); }
+  void StartRead(Response* resp) { reader_->Read(resp); }
+
+  void AddHold() { AddMultipleHolds(1); }
+  void AddMultipleHolds(int holds) { reader_->AddHold(holds); }
+  void RemoveHold() { reader_->RemoveHold(); }
+
+  virtual void OnDone(const ::grpc::Status& s) {}
+  virtual void OnReadInitialMetadataDone(bool ok) {}
+  virtual void OnReadDone(bool ok) {}
+
+ private:
+  friend class ClientCallbackReader<Response>;
+  void BindReader(ClientCallbackReader<Response>* reader) { reader_ = reader; }
+  ClientCallbackReader<Response>* reader_;
+};
+
+/// \a ClientWriteReactor is the interface for a client-streaming RPC.
+/// All public methods behave as in ClientBidiReactor.
+template <class Request>
+class ClientWriteReactor {
+ public:
+  virtual ~ClientWriteReactor() {}
+
+  void StartCall() { writer_->StartCall(); }
+  void StartWrite(const Request* req) {
+    StartWrite(req, ::grpc::WriteOptions());
+  }
+  void StartWrite(const Request* req, ::grpc::WriteOptions options) {
+    writer_->Write(req, std::move(options));
+  }
+  void StartWriteLast(const Request* req, ::grpc::WriteOptions options) {
+    StartWrite(req, std::move(options.set_last_message()));
+  }
+  void StartWritesDone() { writer_->WritesDone(); }
+
+  void AddHold() { AddMultipleHolds(1); }
+  void AddMultipleHolds(int holds) { writer_->AddHold(holds); }
+  void RemoveHold() { writer_->RemoveHold(); }
+
+  virtual void OnDone(const ::grpc::Status& s) {}
+  virtual void OnReadInitialMetadataDone(bool ok) {}
+  virtual void OnWriteDone(bool ok) {}
+  virtual void OnWritesDoneDone(bool ok) {}
+
+ private:
+  friend class ClientCallbackWriter<Request>;
+  void BindWriter(ClientCallbackWriter<Request>* writer) { writer_ = writer; }
+  ClientCallbackWriter<Request>* writer_;
+};
+
+/// \a ClientUnaryReactor is a reactor-style interface for a unary RPC.
+/// This is _not_ a common way of invoking a unary RPC. In practice, this
+/// option should be used only if the unary RPC wants to receive initial
+/// metadata without waiting for the response to complete. Most deployments of
+/// RPC systems do not use this option, but it is needed for generality.
+/// All public methods behave as in ClientBidiReactor.
+/// StartCall is included for consistency with the other reactor flavors: even
+/// though there are no StartRead or StartWrite operations to queue before the
+/// call (that is part of the unary call itself) and there is no reactor object
+/// being created as a result of this call, we keep a consistent 2-phase
+/// initiation API among all the reactor flavors.
+class ClientUnaryReactor {
+ public:
+  virtual ~ClientUnaryReactor() {}
+
+  void StartCall() { call_->StartCall(); }
+  virtual void OnDone(const ::grpc::Status& s) {}
+  virtual void OnReadInitialMetadataDone(bool ok) {}
+
+ private:
+  friend class ClientCallbackUnary;
+  void BindCall(ClientCallbackUnary* call) { call_ = call; }
+  ClientCallbackUnary* call_;
+};
+
+// Define function out-of-line from class to avoid forward declaration issue
+inline void ClientCallbackUnary::BindReactor(ClientUnaryReactor* reactor) {
+  reactor->BindCall(this);
+}
+
+}  // namespace experimental
+
+namespace internal {
+
+// Forward declare factory classes for friendship
+template <class Request, class Response>
+class ClientCallbackReaderWriterFactory;
+template <class Response>
+class ClientCallbackReaderFactory;
+template <class Request>
+class ClientCallbackWriterFactory;
+
+template <class Request, class Response>
+class ClientCallbackReaderWriterImpl
+    : public experimental::ClientCallbackReaderWriter<Request, Response> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientCallbackReaderWriterImpl));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void MaybeFinish() {
+    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                         1, std::memory_order_acq_rel) == 1)) {
+      ::grpc::Status s = std::move(finish_status_);
+      auto* reactor = reactor_;
+      auto* call = call_.call();
+      this->~ClientCallbackReaderWriterImpl();
+      ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+      reactor->OnDone(s);
+    }
+  }
+
+  void StartCall() override {
+    // This call initiates two batches, plus any backlog, each with a callback
+    // 1. Send initial metadata (unless corked) + recv initial metadata
+    // 2. Any read backlog
+    // 3. Any write backlog
+    // 4. Recv trailing metadata, on_completion callback
+    started_ = true;
+
+    start_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnReadInitialMetadataDone(ok);
+                     MaybeFinish();
+                   },
+                   &start_ops_);
+    if (!start_corked_) {
+      start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+    }
+    start_ops_.RecvInitialMetadata(context_);
+    start_ops_.set_core_cq_tag(&start_tag_);
+    call_.PerformOps(&start_ops_);
+
+    // Also set up the read and write tags so that they don't have to be set up
+    // each time
+    write_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnWriteDone(ok);
+                     MaybeFinish();
+                   },
+                   &write_ops_);
+    write_ops_.set_core_cq_tag(&write_tag_);
+
+    read_tag_.Set(call_.call(),
+                  [this](bool ok) {
+                    reactor_->OnReadDone(ok);
+                    MaybeFinish();
+                  },
+                  &read_ops_);
+    read_ops_.set_core_cq_tag(&read_tag_);
+    if (read_ops_at_start_) {
+      call_.PerformOps(&read_ops_);
+    }
+
+    if (write_ops_at_start_) {
+      call_.PerformOps(&write_ops_);
+    }
+
+    if (writes_done_ops_at_start_) {
+      call_.PerformOps(&writes_done_ops_);
+    }
+
+    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
+                    &finish_ops_);
+    finish_ops_.ClientRecvStatus(context_, &finish_status_);
+    finish_ops_.set_core_cq_tag(&finish_tag_);
+    call_.PerformOps(&finish_ops_);
+  }
+
+  void Read(Response* msg) override {
+    read_ops_.RecvMessage(msg);
+    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+    if (started_) {
+      call_.PerformOps(&read_ops_);
+    } else {
+      read_ops_at_start_ = true;
+    }
+  }
+
+  void Write(const Request* msg, ::grpc::WriteOptions options) override {
+    if (start_corked_) {
+      write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      write_ops_.ClientSendClose();
+    }
+    // TODO(vjpai): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(msg, options).ok());
+    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+    if (started_) {
+      call_.PerformOps(&write_ops_);
+    } else {
+      write_ops_at_start_ = true;
+    }
+  }
+  void WritesDone() override {
+    if (start_corked_) {
+      writes_done_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                           context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+    writes_done_ops_.ClientSendClose();
+    writes_done_tag_.Set(call_.call(),
+                         [this](bool ok) {
+                           reactor_->OnWritesDoneDone(ok);
+                           MaybeFinish();
+                         },
+                         &writes_done_ops_);
+    writes_done_ops_.set_core_cq_tag(&writes_done_tag_);
+    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+    if (started_) {
+      call_.PerformOps(&writes_done_ops_);
+    } else {
+      writes_done_ops_at_start_ = true;
+    }
+  }
+
+  void AddHold(int holds) override {
+    callbacks_outstanding_.fetch_add(holds, std::memory_order_relaxed);
+  }
+  void RemoveHold() override { MaybeFinish(); }
+
+ private:
+  friend class ClientCallbackReaderWriterFactory<Request, Response>;
+
+  ClientCallbackReaderWriterImpl(
+      grpc::internal::Call call, ::grpc_impl::ClientContext* context,
+      experimental::ClientBidiReactor<Request, Response>* reactor)
+      : context_(context),
+        call_(call),
+        reactor_(reactor),
+        start_corked_(context_->initial_metadata_corked_) {
+    this->BindReactor(reactor);
+  }
+
+  ::grpc_impl::ClientContext* const context_;
+  grpc::internal::Call call_;
+  experimental::ClientBidiReactor<Request, Response>* const reactor_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpRecvInitialMetadata>
+      start_ops_;
+  grpc::internal::CallbackWithSuccessTag start_tag_;
+  bool start_corked_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpClientRecvStatus> finish_ops_;
+  grpc::internal::CallbackWithSuccessTag finish_tag_;
+  ::grpc::Status finish_status_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpSendMessage,
+                            grpc::internal::CallOpClientSendClose>
+      write_ops_;
+  grpc::internal::CallbackWithSuccessTag write_tag_;
+  bool write_ops_at_start_{false};
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpClientSendClose>
+      writes_done_ops_;
+  grpc::internal::CallbackWithSuccessTag writes_done_tag_;
+  bool writes_done_ops_at_start_{false};
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpRecvMessage<Response>>
+      read_ops_;
+  grpc::internal::CallbackWithSuccessTag read_tag_;
+  bool read_ops_at_start_{false};
+
+  // Minimum of 2 callbacks to pre-register for start and finish
+  std::atomic<intptr_t> callbacks_outstanding_{2};
+  bool started_{false};
+};
+
+template <class Request, class Response>
+class ClientCallbackReaderWriterFactory {
+ public:
+  static void Create(
+      ::grpc::ChannelInterface* channel,
+      const ::grpc::internal::RpcMethod& method,
+      ::grpc_impl::ClientContext* context,
+      experimental::ClientBidiReactor<Request, Response>* reactor) {
+    grpc::internal::Call call =
+        channel->CreateCall(method, context, channel->CallbackCQ());
+
+    ::grpc::g_core_codegen_interface->grpc_call_ref(call.call());
+    new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientCallbackReaderWriterImpl<Request, Response>)))
+        ClientCallbackReaderWriterImpl<Request, Response>(call, context,
+                                                          reactor);
+  }
+};
+
+template <class Response>
+class ClientCallbackReaderImpl
+    : public experimental::ClientCallbackReader<Response> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientCallbackReaderImpl));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void MaybeFinish() {
+    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                         1, std::memory_order_acq_rel) == 1)) {
+      ::grpc::Status s = std::move(finish_status_);
+      auto* reactor = reactor_;
+      auto* call = call_.call();
+      this->~ClientCallbackReaderImpl();
+      ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+      reactor->OnDone(s);
+    }
+  }
+
+  void StartCall() override {
+    // This call initiates two batches, plus any backlog, each with a callback
+    // 1. Send initial metadata (unless corked) + recv initial metadata
+    // 2. Any backlog
+    // 3. Recv trailing metadata, on_completion callback
+    started_ = true;
+
+    start_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnReadInitialMetadataDone(ok);
+                     MaybeFinish();
+                   },
+                   &start_ops_);
+    start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                   context_->initial_metadata_flags());
+    start_ops_.RecvInitialMetadata(context_);
+    start_ops_.set_core_cq_tag(&start_tag_);
+    call_.PerformOps(&start_ops_);
+
+    // Also set up the read tag so it doesn't have to be set up each time
+    read_tag_.Set(call_.call(),
+                  [this](bool ok) {
+                    reactor_->OnReadDone(ok);
+                    MaybeFinish();
+                  },
+                  &read_ops_);
+    read_ops_.set_core_cq_tag(&read_tag_);
+    if (read_ops_at_start_) {
+      call_.PerformOps(&read_ops_);
+    }
+
+    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
+                    &finish_ops_);
+    finish_ops_.ClientRecvStatus(context_, &finish_status_);
+    finish_ops_.set_core_cq_tag(&finish_tag_);
+    call_.PerformOps(&finish_ops_);
+  }
+
+  void Read(Response* msg) override {
+    read_ops_.RecvMessage(msg);
+    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+    if (started_) {
+      call_.PerformOps(&read_ops_);
+    } else {
+      read_ops_at_start_ = true;
+    }
+  }
+
+  void AddHold(int holds) override {
+    callbacks_outstanding_.fetch_add(holds, std::memory_order_relaxed);
+  }
+  void RemoveHold() override { MaybeFinish(); }
+
+ private:
+  friend class ClientCallbackReaderFactory<Response>;
+
+  template <class Request>
+  ClientCallbackReaderImpl(::grpc::internal::Call call,
+                           ::grpc_impl::ClientContext* context,
+                           Request* request,
+                           experimental::ClientReadReactor<Response>* reactor)
+      : context_(context), call_(call), reactor_(reactor) {
+    this->BindReactor(reactor);
+    // TODO(vjpai): don't assert
+    GPR_CODEGEN_ASSERT(start_ops_.SendMessagePtr(request).ok());
+    start_ops_.ClientSendClose();
+  }
+
+  ::grpc_impl::ClientContext* const context_;
+  grpc::internal::Call call_;
+  experimental::ClientReadReactor<Response>* const reactor_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpSendMessage,
+                            grpc::internal::CallOpClientSendClose,
+                            grpc::internal::CallOpRecvInitialMetadata>
+      start_ops_;
+  grpc::internal::CallbackWithSuccessTag start_tag_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpClientRecvStatus> finish_ops_;
+  grpc::internal::CallbackWithSuccessTag finish_tag_;
+  ::grpc::Status finish_status_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpRecvMessage<Response>>
+      read_ops_;
+  grpc::internal::CallbackWithSuccessTag read_tag_;
+  bool read_ops_at_start_{false};
+
+  // Minimum of 2 callbacks to pre-register for start and finish
+  std::atomic<intptr_t> callbacks_outstanding_{2};
+  bool started_{false};
+};
+
+template <class Response>
+class ClientCallbackReaderFactory {
+ public:
+  template <class Request>
+  static void Create(::grpc::ChannelInterface* channel,
+                     const ::grpc::internal::RpcMethod& method,
+                     ::grpc_impl::ClientContext* context,
+                     const Request* request,
+                     experimental::ClientReadReactor<Response>* reactor) {
+    grpc::internal::Call call =
+        channel->CreateCall(method, context, channel->CallbackCQ());
+
+    ::grpc::g_core_codegen_interface->grpc_call_ref(call.call());
+    new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientCallbackReaderImpl<Response>)))
+        ClientCallbackReaderImpl<Response>(call, context, request, reactor);
+  }
+};
+
+template <class Request>
+class ClientCallbackWriterImpl
+    : public experimental::ClientCallbackWriter<Request> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientCallbackWriterImpl));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void MaybeFinish() {
+    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                         1, std::memory_order_acq_rel) == 1)) {
+      ::grpc::Status s = std::move(finish_status_);
+      auto* reactor = reactor_;
+      auto* call = call_.call();
+      this->~ClientCallbackWriterImpl();
+      ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+      reactor->OnDone(s);
+    }
+  }
+
+  void StartCall() override {
+    // This call initiates two batches, plus any backlog, each with a callback
+    // 1. Send initial metadata (unless corked) + recv initial metadata
+    // 2. Any backlog
+    // 3. Recv trailing metadata, on_completion callback
+    started_ = true;
+
+    start_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnReadInitialMetadataDone(ok);
+                     MaybeFinish();
+                   },
+                   &start_ops_);
+    if (!start_corked_) {
+      start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+    }
+    start_ops_.RecvInitialMetadata(context_);
+    start_ops_.set_core_cq_tag(&start_tag_);
+    call_.PerformOps(&start_ops_);
+
+    // Also set up the read and write tags so that they don't have to be set up
+    // each time
+    write_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnWriteDone(ok);
+                     MaybeFinish();
+                   },
+                   &write_ops_);
+    write_ops_.set_core_cq_tag(&write_tag_);
+
+    if (write_ops_at_start_) {
+      call_.PerformOps(&write_ops_);
+    }
+
+    if (writes_done_ops_at_start_) {
+      call_.PerformOps(&writes_done_ops_);
+    }
+
+    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
+                    &finish_ops_);
+    finish_ops_.ClientRecvStatus(context_, &finish_status_);
+    finish_ops_.set_core_cq_tag(&finish_tag_);
+    call_.PerformOps(&finish_ops_);
+  }
+
+  void Write(const Request* msg, ::grpc::WriteOptions options) override {
+    if (start_corked_) {
+      write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      write_ops_.ClientSendClose();
+    }
+    // TODO(vjpai): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(msg, options).ok());
+    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+    if (started_) {
+      call_.PerformOps(&write_ops_);
+    } else {
+      write_ops_at_start_ = true;
+    }
+  }
+  void WritesDone() override {
+    if (start_corked_) {
+      writes_done_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                           context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+    writes_done_ops_.ClientSendClose();
+    writes_done_tag_.Set(call_.call(),
+                         [this](bool ok) {
+                           reactor_->OnWritesDoneDone(ok);
+                           MaybeFinish();
+                         },
+                         &writes_done_ops_);
+    writes_done_ops_.set_core_cq_tag(&writes_done_tag_);
+    callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+    if (started_) {
+      call_.PerformOps(&writes_done_ops_);
+    } else {
+      writes_done_ops_at_start_ = true;
+    }
+  }
+
+  void AddHold(int holds) override {
+    callbacks_outstanding_.fetch_add(holds, std::memory_order_relaxed);
+  }
+  void RemoveHold() override { MaybeFinish(); }
+
+ private:
+  friend class ClientCallbackWriterFactory<Request>;
+
+  template <class Response>
+  ClientCallbackWriterImpl(::grpc::internal::Call call,
+                           ::grpc_impl::ClientContext* context,
+                           Response* response,
+                           experimental::ClientWriteReactor<Request>* reactor)
+      : context_(context),
+        call_(call),
+        reactor_(reactor),
+        start_corked_(context_->initial_metadata_corked_) {
+    this->BindReactor(reactor);
+    finish_ops_.RecvMessage(response);
+    finish_ops_.AllowNoMessage();
+  }
+
+  ::grpc_impl::ClientContext* const context_;
+  grpc::internal::Call call_;
+  experimental::ClientWriteReactor<Request>* const reactor_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpRecvInitialMetadata>
+      start_ops_;
+  grpc::internal::CallbackWithSuccessTag start_tag_;
+  bool start_corked_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpGenericRecvMessage,
+                            grpc::internal::CallOpClientRecvStatus>
+      finish_ops_;
+  grpc::internal::CallbackWithSuccessTag finish_tag_;
+  ::grpc::Status finish_status_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpSendMessage,
+                            grpc::internal::CallOpClientSendClose>
+      write_ops_;
+  grpc::internal::CallbackWithSuccessTag write_tag_;
+  bool write_ops_at_start_{false};
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpClientSendClose>
+      writes_done_ops_;
+  grpc::internal::CallbackWithSuccessTag writes_done_tag_;
+  bool writes_done_ops_at_start_{false};
+
+  // Minimum of 2 callbacks to pre-register for start and finish
+  std::atomic<intptr_t> callbacks_outstanding_{2};
+  bool started_{false};
+};
+
+template <class Request>
+class ClientCallbackWriterFactory {
+ public:
+  template <class Response>
+  static void Create(::grpc::ChannelInterface* channel,
+                     const ::grpc::internal::RpcMethod& method,
+                     ::grpc_impl::ClientContext* context, Response* response,
+                     experimental::ClientWriteReactor<Request>* reactor) {
+    grpc::internal::Call call =
+        channel->CreateCall(method, context, channel->CallbackCQ());
+
+    ::grpc::g_core_codegen_interface->grpc_call_ref(call.call());
+    new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientCallbackWriterImpl<Request>)))
+        ClientCallbackWriterImpl<Request>(call, context, response, reactor);
+  }
+};
+
+class ClientCallbackUnaryImpl final : public experimental::ClientCallbackUnary {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientCallbackUnaryImpl));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void StartCall() override {
+    // This call initiates two batches, each with a callback
+    // 1. Send initial metadata + write + writes done + recv initial metadata
+    // 2. Read message, recv trailing metadata
+    started_ = true;
+
+    start_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnReadInitialMetadataDone(ok);
+                     MaybeFinish();
+                   },
+                   &start_ops_);
+    start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                   context_->initial_metadata_flags());
+    start_ops_.RecvInitialMetadata(context_);
+    start_ops_.set_core_cq_tag(&start_tag_);
+    call_.PerformOps(&start_ops_);
+
+    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
+                    &finish_ops_);
+    finish_ops_.ClientRecvStatus(context_, &finish_status_);
+    finish_ops_.set_core_cq_tag(&finish_tag_);
+    call_.PerformOps(&finish_ops_);
+  }
+
+  void MaybeFinish() {
+    if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                         1, std::memory_order_acq_rel) == 1)) {
+      ::grpc::Status s = std::move(finish_status_);
+      auto* reactor = reactor_;
+      auto* call = call_.call();
+      this->~ClientCallbackUnaryImpl();
+      ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+      reactor->OnDone(s);
+    }
+  }
+
+ private:
+  friend class ClientCallbackUnaryFactory;
+
+  template <class Request, class Response>
+  ClientCallbackUnaryImpl(::grpc::internal::Call call,
+                          ::grpc_impl::ClientContext* context, Request* request,
+                          Response* response,
+                          experimental::ClientUnaryReactor* reactor)
+      : context_(context), call_(call), reactor_(reactor) {
+    this->BindReactor(reactor);
+    // TODO(vjpai): don't assert
+    GPR_CODEGEN_ASSERT(start_ops_.SendMessagePtr(request).ok());
+    start_ops_.ClientSendClose();
+    finish_ops_.RecvMessage(response);
+    finish_ops_.AllowNoMessage();
+  }
+
+  ::grpc_impl::ClientContext* const context_;
+  grpc::internal::Call call_;
+  experimental::ClientUnaryReactor* const reactor_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                            grpc::internal::CallOpSendMessage,
+                            grpc::internal::CallOpClientSendClose,
+                            grpc::internal::CallOpRecvInitialMetadata>
+      start_ops_;
+  grpc::internal::CallbackWithSuccessTag start_tag_;
+
+  grpc::internal::CallOpSet<grpc::internal::CallOpGenericRecvMessage,
+                            grpc::internal::CallOpClientRecvStatus>
+      finish_ops_;
+  grpc::internal::CallbackWithSuccessTag finish_tag_;
+  ::grpc::Status finish_status_;
+
+  // This call will have 2 callbacks: start and finish
+  std::atomic<intptr_t> callbacks_outstanding_{2};
+  bool started_{false};
+};
+
+class ClientCallbackUnaryFactory {
+ public:
+  template <class Request, class Response>
+  static void Create(::grpc::ChannelInterface* channel,
+                     const ::grpc::internal::RpcMethod& method,
+                     ::grpc_impl::ClientContext* context,
+                     const Request* request, Response* response,
+                     experimental::ClientUnaryReactor* reactor) {
+    grpc::internal::Call call =
+        channel->CreateCall(method, context, channel->CallbackCQ());
+
+    ::grpc::g_core_codegen_interface->grpc_call_ref(call.call());
+
+    new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientCallbackUnaryImpl)))
+        ClientCallbackUnaryImpl(call, context, request, response, reactor);
+  }
+};
+
+}  // namespace internal
+}  // namespace grpc_impl
+#endif  // GRPCPP_IMPL_CODEGEN_CLIENT_CALLBACK_IMPL_H

include/grpcpp/impl/codegen/client_context_impl.h

@@ -63,10 +63,19 @@ class ChannelInterface;
 
 namespace internal {
 class RpcMethod;
-class CallOpClientRecvStatus;
-class CallOpRecvInitialMetadata;
 template <class InputMessage, class OutputMessage>
 class BlockingUnaryCallImpl;
+class CallOpClientRecvStatus;
+class CallOpRecvInitialMetadata;
+}  // namespace internal
+
+namespace testing {
+class InteropClientContextInspector;
+}  // namespace testing
+}  // namespace grpc
+namespace grpc_impl {
+
+namespace internal {
 template <class InputMessage, class OutputMessage>
 class CallbackUnaryCallImpl;
 template <class Request, class Response>
@@ -78,6 +87,10 @@ class ClientCallbackWriterImpl;
 class ClientCallbackUnaryImpl;
 }  // namespace internal
 
+class CallCredentials;
+class Channel;
+class CompletionQueue;
+class ServerContext;
 template <class R>
 class ClientReader;
 template <class W>
@@ -93,17 +106,6 @@ class ClientAsyncReaderWriter;
 template <class R>
 class ClientAsyncResponseReader;
 
-namespace testing {
-class InteropClientContextInspector;
-}  // namespace testing
-}  // namespace grpc
-namespace grpc_impl {
-
-class CallCredentials;
-class Channel;
-class CompletionQueue;
-class ServerContext;
-
 /// Options for \a ClientContext::FromServerContext specifying which traits from
 /// the \a ServerContext to propagate (copy) from it into a new \a
 /// ClientContext.
@@ -398,30 +400,30 @@ class ClientContext {
   friend class ::grpc::internal::CallOpRecvInitialMetadata;
   friend class ::grpc_impl::Channel;
   template <class R>
-  friend class ::grpc::ClientReader;
+  friend class ::grpc_impl::ClientReader;
   template <class W>
-  friend class ::grpc::ClientWriter;
+  friend class ::grpc_impl::ClientWriter;
   template <class W, class R>
-  friend class ::grpc::ClientReaderWriter;
+  friend class ::grpc_impl::ClientReaderWriter;
   template <class R>
-  friend class ::grpc::ClientAsyncReader;
+  friend class ::grpc_impl::ClientAsyncReader;
   template <class W>
-  friend class ::grpc::ClientAsyncWriter;
+  friend class ::grpc_impl::ClientAsyncWriter;
   template <class W, class R>
-  friend class ::grpc::ClientAsyncReaderWriter;
+  friend class ::grpc_impl::ClientAsyncReaderWriter;
   template <class R>
-  friend class ::grpc::ClientAsyncResponseReader;
+  friend class ::grpc_impl::ClientAsyncResponseReader;
   template <class InputMessage, class OutputMessage>
   friend class ::grpc::internal::BlockingUnaryCallImpl;
   template <class InputMessage, class OutputMessage>
-  friend class ::grpc::internal::CallbackUnaryCallImpl;
+  friend class ::grpc_impl::internal::CallbackUnaryCallImpl;
   template <class Request, class Response>
-  friend class ::grpc::internal::ClientCallbackReaderWriterImpl;
+  friend class ::grpc_impl::internal::ClientCallbackReaderWriterImpl;
   template <class Response>
-  friend class ::grpc::internal::ClientCallbackReaderImpl;
+  friend class ::grpc_impl::internal::ClientCallbackReaderImpl;
   template <class Request>
-  friend class ::grpc::internal::ClientCallbackWriterImpl;
-  friend class ::grpc::internal::ClientCallbackUnaryImpl;
+  friend class ::grpc_impl::internal::ClientCallbackWriterImpl;
+  friend class ::grpc_impl::internal::ClientCallbackUnaryImpl;
 
   // Used by friend class CallOpClientRecvStatus
   void set_debug_error_string(const grpc::string& debug_error_string) {

include/grpcpp/impl/codegen/client_unary_call.h

@@ -49,10 +49,10 @@ class BlockingUnaryCallImpl {
   BlockingUnaryCallImpl(ChannelInterface* channel, const RpcMethod& method,
                         grpc_impl::ClientContext* context,
                         const InputMessage& request, OutputMessage* result) {
-    CompletionQueue cq(grpc_completion_queue_attributes{
+    ::grpc_impl::CompletionQueue cq(grpc_completion_queue_attributes{
         GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
         nullptr});  // Pluckable completion queue
-    Call call(channel->CreateCall(method, context, &cq));
+    ::grpc::internal::Call call(channel->CreateCall(method, context, &cq));
     CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
               CallOpRecvInitialMetadata, CallOpRecvMessage<OutputMessage>,
               CallOpClientSendClose, CallOpClientRecvStatus>

include/grpcpp/impl/codegen/completion_queue_impl.h

@@ -47,9 +47,6 @@ class Channel;
 class Server;
 class ServerBuilder;
 class ServerContext;
-}  // namespace grpc_impl
-namespace grpc {
-
 template <class R>
 class ClientReader;
 template <class W>
@@ -64,6 +61,8 @@ namespace internal {
 template <class W, class R>
 class ServerReaderWriterBody;
 }  // namespace internal
+}  // namespace grpc_impl
+namespace grpc {
 
 class ChannelInterface;
 class ServerInterface;
@@ -255,17 +254,17 @@ class CompletionQueue : private ::grpc::GrpcLibraryCodegen {
   // Friend synchronous wrappers so that they can access Pluck(), which is
   // a semi-private API geared towards the synchronous implementation.
   template <class R>
-  friend class ::grpc::ClientReader;
+  friend class ::grpc_impl::ClientReader;
   template <class W>
-  friend class ::grpc::ClientWriter;
+  friend class ::grpc_impl::ClientWriter;
   template <class W, class R>
-  friend class ::grpc::ClientReaderWriter;
+  friend class ::grpc_impl::ClientReaderWriter;
   template <class R>
-  friend class ::grpc::ServerReader;
+  friend class ::grpc_impl::ServerReader;
   template <class W>
-  friend class ::grpc::ServerWriter;
+  friend class ::grpc_impl::ServerWriter;
   template <class W, class R>
-  friend class ::grpc::internal::ServerReaderWriterBody;
+  friend class ::grpc_impl::internal::ServerReaderWriterBody;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class ::grpc::internal::RpcMethodHandler;
   template <class ServiceType, class RequestType, class ResponseType>

include/grpcpp/impl/codegen/server_callback.h

@@ -19,1141 +19,26 @@
 #ifndef GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H
 #define GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H
 
-#include <atomic>
-#include <functional>
-#include <type_traits>
-
-#include <grpcpp/impl/codegen/call.h>
-#include <grpcpp/impl/codegen/call_op_set.h>
-#include <grpcpp/impl/codegen/callback_common.h>
-#include <grpcpp/impl/codegen/config.h>
-#include <grpcpp/impl/codegen/core_codegen_interface.h>
-#include <grpcpp/impl/codegen/message_allocator.h>
-#include <grpcpp/impl/codegen/server_context_impl.h>
-#include <grpcpp/impl/codegen/server_interface.h>
-#include <grpcpp/impl/codegen/status.h>
+#include <grpcpp/impl/codegen/server_callback_impl.h>
 
 namespace grpc {
-
-// Declare base class of all reactors as internal
-namespace internal {
-
-// Forward declarations
-template <class Request, class Response>
-class CallbackClientStreamingHandler;
-template <class Request, class Response>
-class CallbackServerStreamingHandler;
-template <class Request, class Response>
-class CallbackBidiHandler;
-
-class ServerReactor {
- public:
-  virtual ~ServerReactor() = default;
-  virtual void OnDone() = 0;
-  virtual void OnCancel() = 0;
-
- private:
-  friend class ::grpc_impl::ServerContext;
-  template <class Request, class Response>
-  friend class CallbackClientStreamingHandler;
-  template <class Request, class Response>
-  friend class CallbackServerStreamingHandler;
-  template <class Request, class Response>
-  friend class CallbackBidiHandler;
-
-  // The ServerReactor is responsible for tracking when it is safe to call
-  // OnCancel. This function should not be called until after OnStarted is done
-  // and the RPC has completed with a cancellation. This is tracked by counting
-  // how many of these conditions have been met and calling OnCancel when none
-  // remain unmet.
-
-  void MaybeCallOnCancel() {
-    if (GPR_UNLIKELY(on_cancel_conditions_remaining_.fetch_sub(
-                         1, std::memory_order_acq_rel) == 1)) {
-      OnCancel();
-    }
-  }
-
-  std::atomic<intptr_t> on_cancel_conditions_remaining_{2};
-};
-
-template <class Request, class Response>
-class DefaultMessageHolder
-    : public experimental::MessageHolder<Request, Response> {
- public:
-  DefaultMessageHolder() {
-    this->set_request(&request_obj_);
-    this->set_response(&response_obj_);
-  }
-  void Release() override {
-    // the object is allocated in the call arena.
-    this->~DefaultMessageHolder<Request, Response>();
-  }
-
- private:
-  Request request_obj_;
-  Response response_obj_;
-};
-
-}  // namespace internal
-
 namespace experimental {
-
-// Forward declarations
-template <class Request, class Response>
-class ServerReadReactor;
-template <class Request, class Response>
-class ServerWriteReactor;
-template <class Request, class Response>
-class ServerBidiReactor;
-
-// For unary RPCs, the exposed controller class is only an interface
-// and the actual implementation is an internal class.
-class ServerCallbackRpcController {
- public:
-  virtual ~ServerCallbackRpcController() = default;
-
-  // The method handler must call this function when it is done so that
-  // the library knows to free its resources
-  virtual void Finish(Status s) = 0;
-
-  // Allow the method handler to push out the initial metadata before
-  // the response and status are ready
-  virtual void SendInitialMetadata(std::function<void(bool)>) = 0;
-
-  /// SetCancelCallback passes in a callback to be called when the RPC is
-  /// canceled for whatever reason (streaming calls have OnCancel instead). This
-  /// is an advanced and uncommon use with several important restrictions. This
-  /// function may not be called more than once on the same RPC.
-  ///
-  /// If code calls SetCancelCallback on an RPC, it must also call
-  /// ClearCancelCallback before calling Finish on the RPC controller. That
-  /// method makes sure that no cancellation callback is executed for this RPC
-  /// beyond the point of its return. ClearCancelCallback may be called even if
-  /// SetCancelCallback was not called for this RPC, and it may be called
-  /// multiple times. It _must_ be called if SetCancelCallback was called for
-  /// this RPC.
-  ///
-  /// The callback should generally be lightweight and nonblocking and primarily
-  /// concerned with clearing application state related to the RPC or causing
-  /// operations (such as cancellations) to happen on dependent RPCs.
-  ///
-  /// If the RPC is already canceled at the time that SetCancelCallback is
-  /// called, the callback is invoked immediately.
-  ///
-  /// The cancellation callback may be executed concurrently with the method
-  /// handler that invokes it but will certainly not issue or execute after the
-  /// return of ClearCancelCallback. If ClearCancelCallback is invoked while the
-  /// callback is already executing, the callback will complete its execution
-  /// before ClearCancelCallback takes effect.
-  ///
-  /// To preserve the orderings described above, the callback may be called
-  /// under a lock that is also used for ClearCancelCallback and
-  /// ServerContext::IsCancelled, so the callback CANNOT call either of those
-  /// operations on this RPC or any other function that causes those operations
-  /// to be called before the callback completes.
-  virtual void SetCancelCallback(std::function<void()> callback) = 0;
-  virtual void ClearCancelCallback() = 0;
-
-  // NOTE: This is an API for advanced users who need custom allocators.
-  // Get and maybe mutate the allocator state associated with the current RPC.
-  virtual RpcAllocatorState* GetRpcAllocatorState() = 0;
-};
-
-// NOTE: The actual streaming object classes are provided
-// as API only to support mocking. There are no implementations of
-// these class interfaces in the API.
-template <class Request>
-class ServerCallbackReader {
- public:
-  virtual ~ServerCallbackReader() {}
-  virtual void Finish(Status s) = 0;
-  virtual void SendInitialMetadata() = 0;
-  virtual void Read(Request* msg) = 0;
-
- protected:
-  template <class Response>
-  void BindReactor(ServerReadReactor<Request, Response>* reactor) {
-    reactor->InternalBindReader(this);
-  }
-};
-
-template <class Response>
-class ServerCallbackWriter {
- public:
-  virtual ~ServerCallbackWriter() {}
-
-  virtual void Finish(Status s) = 0;
-  virtual void SendInitialMetadata() = 0;
-  virtual void Write(const Response* msg, WriteOptions options) = 0;
-  virtual void WriteAndFinish(const Response* msg, WriteOptions options,
-                              Status s) {
-    // Default implementation that can/should be overridden
-    Write(msg, std::move(options));
-    Finish(std::move(s));
-  }
-
- protected:
-  template <class Request>
-  void BindReactor(ServerWriteReactor<Request, Response>* reactor) {
-    reactor->InternalBindWriter(this);
-  }
-};
-
-template <class Request, class Response>
-class ServerCallbackReaderWriter {
- public:
-  virtual ~ServerCallbackReaderWriter() {}
-
-  virtual void Finish(Status s) = 0;
-  virtual void SendInitialMetadata() = 0;
-  virtual void Read(Request* msg) = 0;
-  virtual void Write(const Response* msg, WriteOptions options) = 0;
-  virtual void WriteAndFinish(const Response* msg, WriteOptions options,
-                              Status s) {
-    // Default implementation that can/should be overridden
-    Write(msg, std::move(options));
-    Finish(std::move(s));
-  }
-
- protected:
-  void BindReactor(ServerBidiReactor<Request, Response>* reactor) {
-    reactor->InternalBindStream(this);
-  }
-};
-
-// The following classes are the reactor interfaces that are to be implemented
-// by the user, returned as the result of the method handler for a callback
-// method, and activated by the call to OnStarted. The library guarantees that
-// OnStarted will be called for any reactor that has been created using a
-// method handler registered on a service. No operation initiation method may be
-// called until after the call to OnStarted.
-// Note that none of the classes are pure; all reactions have a default empty
-// reaction so that the user class only needs to override those classes that it
-// cares about.
-
-/// \a ServerBidiReactor is the interface for a bidirectional streaming RPC.
 template <class Request, class Response>
-class ServerBidiReactor : public internal::ServerReactor {
- public:
-  ~ServerBidiReactor() = default;
-
-  /// Do NOT call any operation initiation method (names that start with Start)
-  /// until after the library has called OnStarted on this object.
-
-  /// Send any initial metadata stored in the RPC context. If not invoked,
-  /// any initial metadata will be passed along with the first Write or the
-  /// Finish (if there are no writes).
-  void StartSendInitialMetadata() { stream_->SendInitialMetadata(); }
-
-  /// Initiate a read operation.
-  ///
-  /// \param[out] req Where to eventually store the read message. Valid when
-  ///                 the library calls OnReadDone
-  void StartRead(Request* req) { stream_->Read(req); }
-
-  /// Initiate a write operation.
-  ///
-  /// \param[in] resp The message to be written. The library takes temporary
-  ///                 ownership until OnWriteDone, at which point the
-  ///                 application regains ownership of resp.
-  void StartWrite(const Response* resp) { StartWrite(resp, WriteOptions()); }
-
-  /// Initiate a write operation with specified options.
-  ///
-  /// \param[in] resp The message to be written. The library takes temporary
-  ///                 ownership until OnWriteDone, at which point the
-  ///                 application regains ownership of resp.
-  /// \param[in] options The WriteOptions to use for writing this message
-  void StartWrite(const Response* resp, WriteOptions options) {
-    stream_->Write(resp, std::move(options));
-  }
-
-  /// Initiate a write operation with specified options and final RPC Status,
-  /// which also causes any trailing metadata for this RPC to be sent out.
-  /// StartWriteAndFinish is like merging StartWriteLast and Finish into a
-  /// single step. A key difference, though, is that this operation doesn't have
-  /// an OnWriteDone reaction - it is considered complete only when OnDone is
-  /// available. An RPC can either have StartWriteAndFinish or Finish, but not
-  /// both.
-  ///
-  /// \param[in] resp The message to be written. The library takes temporary
-  ///                 ownership until Onone, at which point the application
-  ///                 regains ownership of resp.
-  /// \param[in] options The WriteOptions to use for writing this message
-  /// \param[in] s The status outcome of this RPC
-  void StartWriteAndFinish(const Response* resp, WriteOptions options,
-                           Status s) {
-    stream_->WriteAndFinish(resp, std::move(options), std::move(s));
-  }
-
-  /// Inform system of a planned write operation with specified options, but
-  /// allow the library to schedule the actual write coalesced with the writing
-  /// of trailing metadata (which takes place on a Finish call).
-  ///
-  /// \param[in] resp The message to be written. The library takes temporary
-  ///                 ownership until OnWriteDone, at which point the
-  ///                 application regains ownership of resp.
-  /// \param[in] options The WriteOptions to use for writing this message
-  void StartWriteLast(const Response* resp, WriteOptions options) {
-    StartWrite(resp, std::move(options.set_last_message()));
-  }
-
-  /// Indicate that the stream is to be finished and the trailing metadata and
-  /// RPC status are to be sent. Every RPC MUST be finished using either Finish
-  /// or StartWriteAndFinish (but not both), even if the RPC is already
-  /// cancelled.
-  ///
-  /// \param[in] s The status outcome of this RPC
-  void Finish(Status s) { stream_->Finish(std::move(s)); }
-
-  /// Notify the application that a streaming RPC has started and that it is now
-  /// ok to call any operation initiation method. An RPC is considered started
-  /// after the server has received all initial metadata from the client, which
-  /// is a result of the client calling StartCall().
-  ///
-  /// \param[in] context The context object now associated with this RPC
-  virtual void OnStarted(::grpc_impl::ServerContext* context) {}
-
-  /// Notifies the application that an explicit StartSendInitialMetadata
-  /// operation completed. Not used when the sending of initial metadata
-  /// piggybacks onto the first write.
-  ///
-  /// \param[in] ok Was it successful? If false, no further write-side operation
-  ///               will succeed.
-  virtual void OnSendInitialMetadataDone(bool ok) {}
-
-  /// Notifies the application that a StartRead operation completed.
-  ///
-  /// \param[in] ok Was it successful? If false, no further read-side operation
-  ///               will succeed.
-  virtual void OnReadDone(bool ok) {}
-
-  /// Notifies the application that a StartWrite (or StartWriteLast) operation
-  /// completed.
-  ///
-  /// \param[in] ok Was it successful? If false, no further write-side operation
-  ///               will succeed.
-  virtual void OnWriteDone(bool ok) {}
-
-  /// Notifies the application that all operations associated with this RPC
-  /// have completed. This is an override (from the internal base class) but not
-  /// final, so derived classes should override it if they want to take action.
-  void OnDone() override {}
-
-  /// Notifies the application that this RPC has been cancelled. This is an
-  /// override (from the internal base class) but not final, so derived classes
-  /// should override it if they want to take action.
-  void OnCancel() override {}
-
- private:
-  friend class ServerCallbackReaderWriter<Request, Response>;
-  // May be overridden by internal implementation details. This is not a public
-  // customization point.
-  virtual void InternalBindStream(
-      ServerCallbackReaderWriter<Request, Response>* stream) {
-    stream_ = stream;
-  }
+using ServerReadReactor =
+    ::grpc_impl::experimental::ServerReadReactor<Request, Response>;
 
-  ServerCallbackReaderWriter<Request, Response>* stream_;
-};
-
-/// \a ServerReadReactor is the interface for a client-streaming RPC.
 template <class Request, class Response>
-class ServerReadReactor : public internal::ServerReactor {
- public:
-  ~ServerReadReactor() = default;
-
-  /// The following operation initiations are exactly like ServerBidiReactor.
-  void StartSendInitialMetadata() { reader_->SendInitialMetadata(); }
-  void StartRead(Request* req) { reader_->Read(req); }
-  void Finish(Status s) { reader_->Finish(std::move(s)); }
-
-  /// Similar to ServerBidiReactor::OnStarted, except that this also provides
-  /// the response object that the stream fills in before calling Finish.
-  /// (It must be filled in if status is OK, but it may be filled in otherwise.)
-  ///
-  /// \param[in] context The context object now associated with this RPC
-  /// \param[in] resp The response object to be used by this RPC
-  virtual void OnStarted(::grpc_impl::ServerContext* context, Response* resp) {}
-
-  /// The following notifications are exactly like ServerBidiReactor.
-  virtual void OnSendInitialMetadataDone(bool ok) {}
-  virtual void OnReadDone(bool ok) {}
-  void OnDone() override {}
-  void OnCancel() override {}
-
- private:
-  friend class ServerCallbackReader<Request>;
-  // May be overridden by internal implementation details. This is not a public
-  // customization point.
-  virtual void InternalBindReader(ServerCallbackReader<Request>* reader) {
-    reader_ = reader;
-  }
+using ServerWriteReactor =
+    ::grpc_impl::experimental::ServerWriteReactor<Request, Response>;
 
-  ServerCallbackReader<Request>* reader_;
-};
-
-/// \a ServerWriteReactor is the interface for a server-streaming RPC.
 template <class Request, class Response>
-class ServerWriteReactor : public internal::ServerReactor {
- public:
-  ~ServerWriteReactor() = default;
-
-  /// The following operation initiations are exactly like ServerBidiReactor.
-  void StartSendInitialMetadata() { writer_->SendInitialMetadata(); }
-  void StartWrite(const Response* resp) { StartWrite(resp, WriteOptions()); }
-  void StartWrite(const Response* resp, WriteOptions options) {
-    writer_->Write(resp, std::move(options));
-  }
-  void StartWriteAndFinish(const Response* resp, WriteOptions options,
-                           Status s) {
-    writer_->WriteAndFinish(resp, std::move(options), std::move(s));
-  }
-  void StartWriteLast(const Response* resp, WriteOptions options) {
-    StartWrite(resp, std::move(options.set_last_message()));
-  }
-  void Finish(Status s) { writer_->Finish(std::move(s)); }
-
-  /// Similar to ServerBidiReactor::OnStarted, except that this also provides
-  /// the request object sent by the client.
-  ///
-  /// \param[in] context The context object now associated with this RPC
-  /// \param[in] req The request object sent by the client
-  virtual void OnStarted(::grpc_impl::ServerContext* context,
-                         const Request* req) {}
-
-  /// The following notifications are exactly like ServerBidiReactor.
-  virtual void OnSendInitialMetadataDone(bool ok) {}
-  virtual void OnWriteDone(bool ok) {}
-  void OnDone() override {}
-  void OnCancel() override {}
+using ServerBidiReactor =
+    ::grpc_impl::experimental::ServerBidiReactor<Request, Response>;
 
- private:
-  friend class ServerCallbackWriter<Response>;
-  // May be overridden by internal implementation details. This is not a public
-  // customization point.
-  virtual void InternalBindWriter(ServerCallbackWriter<Response>* writer) {
-    writer_ = writer;
-  }
-
-  ServerCallbackWriter<Response>* writer_;
-};
+typedef ::grpc_impl::experimental::ServerCallbackRpcController
+    ServerCallbackRpcController;
 
 }  // namespace experimental
-
-namespace internal {
-
-template <class Request, class Response>
-class UnimplementedReadReactor
-    : public experimental::ServerReadReactor<Request, Response> {
- public:
-  void OnDone() override { delete this; }
-  void OnStarted(::grpc_impl::ServerContext*, Response*) override {
-    this->Finish(Status(StatusCode::UNIMPLEMENTED, ""));
-  }
-};
-
-template <class Request, class Response>
-class UnimplementedWriteReactor
-    : public experimental::ServerWriteReactor<Request, Response> {
- public:
-  void OnDone() override { delete this; }
-  void OnStarted(::grpc_impl::ServerContext*, const Request*) override {
-    this->Finish(Status(StatusCode::UNIMPLEMENTED, ""));
-  }
-};
-
-template <class Request, class Response>
-class UnimplementedBidiReactor
-    : public experimental::ServerBidiReactor<Request, Response> {
- public:
-  void OnDone() override { delete this; }
-  void OnStarted(::grpc_impl::ServerContext*) override {
-    this->Finish(Status(StatusCode::UNIMPLEMENTED, ""));
-  }
-};
-
-template <class RequestType, class ResponseType>
-class CallbackUnaryHandler : public MethodHandler {
- public:
-  CallbackUnaryHandler(
-      std::function<void(::grpc_impl::ServerContext*, const RequestType*,
-                         ResponseType*,
-                         experimental::ServerCallbackRpcController*)>
-          func)
-      : func_(func) {}
-
-  void SetMessageAllocator(
-      experimental::MessageAllocator<RequestType, ResponseType>* allocator) {
-    allocator_ = allocator;
-  }
-
-  void RunHandler(const HandlerParameter& param) final {
-    // Arena allocate a controller structure (that includes request/response)
-    g_core_codegen_interface->grpc_call_ref(param.call->call());
-    auto* allocator_state =
-        static_cast<experimental::MessageHolder<RequestType, ResponseType>*>(
-            param.internal_data);
-    auto* controller = new (g_core_codegen_interface->grpc_call_arena_alloc(
-        param.call->call(), sizeof(ServerCallbackRpcControllerImpl)))
-        ServerCallbackRpcControllerImpl(param.server_context, param.call,
-                                        allocator_state,
-                                        std::move(param.call_requester));
-    Status status = param.status;
-    if (status.ok()) {
-      // Call the actual function handler and expect the user to call finish
-      CatchingCallback(func_, param.server_context, controller->request(),
-                       controller->response(), controller);
-    } else {
-      // if deserialization failed, we need to fail the call
-      controller->Finish(status);
-    }
-  }
-
-  void* Deserialize(grpc_call* call, grpc_byte_buffer* req, Status* status,
-                    void** handler_data) final {
-    ByteBuffer buf;
-    buf.set_buffer(req);
-    RequestType* request = nullptr;
-    experimental::MessageHolder<RequestType, ResponseType>* allocator_state =
-        nullptr;
-    if (allocator_ != nullptr) {
-      allocator_state = allocator_->AllocateMessages();
-    } else {
-      allocator_state = new (g_core_codegen_interface->grpc_call_arena_alloc(
-          call, sizeof(DefaultMessageHolder<RequestType, ResponseType>)))
-          DefaultMessageHolder<RequestType, ResponseType>();
-    }
-    *handler_data = allocator_state;
-    request = allocator_state->request();
-    *status = SerializationTraits<RequestType>::Deserialize(&buf, request);
-    buf.Release();
-    if (status->ok()) {
-      return request;
-    }
-    // Clean up on deserialization failure.
-    allocator_state->Release();
-    return nullptr;
-  }
-
- private:
-  std::function<void(::grpc_impl::ServerContext*, const RequestType*,
-                     ResponseType*, experimental::ServerCallbackRpcController*)>
-      func_;
-  experimental::MessageAllocator<RequestType, ResponseType>* allocator_ =
-      nullptr;
-
-  // The implementation class of ServerCallbackRpcController is a private member
-  // of CallbackUnaryHandler since it is never exposed anywhere, and this allows
-  // it to take advantage of CallbackUnaryHandler's friendships.
-  class ServerCallbackRpcControllerImpl
-      : public experimental::ServerCallbackRpcController {
-   public:
-    void Finish(Status s) override {
-      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
-                      &finish_ops_);
-      if (!ctx_->sent_initial_metadata_) {
-        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                        ctx_->initial_metadata_flags());
-        if (ctx_->compression_level_set()) {
-          finish_ops_.set_compression_level(ctx_->compression_level());
-        }
-        ctx_->sent_initial_metadata_ = true;
-      }
-      // The response is dropped if the status is not OK.
-      if (s.ok()) {
-        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
-                                     finish_ops_.SendMessagePtr(response()));
-      } else {
-        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
-      }
-      finish_ops_.set_core_cq_tag(&finish_tag_);
-      call_.PerformOps(&finish_ops_);
-    }
-
-    void SendInitialMetadata(std::function<void(bool)> f) override {
-      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      // TODO(vjpai): Consider taking f as a move-capture if we adopt C++14
-      //              and if performance of this operation matters
-      meta_tag_.Set(call_.call(),
-                    [this, f](bool ok) {
-                      f(ok);
-                      MaybeDone();
-                    },
-                    &meta_ops_);
-      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                    ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        meta_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-      meta_ops_.set_core_cq_tag(&meta_tag_);
-      call_.PerformOps(&meta_ops_);
-    }
-
-    // Neither SetCancelCallback nor ClearCancelCallback should affect the
-    // callbacks_outstanding_ count since they are paired and both must precede
-    // the invocation of Finish (if they are used at all)
-    void SetCancelCallback(std::function<void()> callback) override {
-      ctx_->SetCancelCallback(std::move(callback));
-    }
-
-    void ClearCancelCallback() override { ctx_->ClearCancelCallback(); }
-
-    experimental::RpcAllocatorState* GetRpcAllocatorState() override {
-      return allocator_state_;
-    }
-
-   private:
-    friend class CallbackUnaryHandler<RequestType, ResponseType>;
-
-    ServerCallbackRpcControllerImpl(
-        ::grpc_impl::ServerContext* ctx, Call* call,
-        experimental::MessageHolder<RequestType, ResponseType>* allocator_state,
-        std::function<void()> call_requester)
-        : ctx_(ctx),
-          call_(*call),
-          allocator_state_(allocator_state),
-          call_requester_(std::move(call_requester)) {
-      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, nullptr);
-    }
-
-    const RequestType* request() { return allocator_state_->request(); }
-    ResponseType* response() { return allocator_state_->response(); }
-
-    void MaybeDone() {
-      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                           1, std::memory_order_acq_rel) == 1)) {
-        grpc_call* call = call_.call();
-        auto call_requester = std::move(call_requester_);
-        allocator_state_->Release();
-        this->~ServerCallbackRpcControllerImpl();  // explicitly call destructor
-        g_core_codegen_interface->grpc_call_unref(call);
-        call_requester();
-      }
-    }
-
-    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
-    CallbackWithSuccessTag meta_tag_;
-    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
-              CallOpServerSendStatus>
-        finish_ops_;
-    CallbackWithSuccessTag finish_tag_;
-
-    ::grpc_impl::ServerContext* ctx_;
-    Call call_;
-    experimental::MessageHolder<RequestType, ResponseType>* const
-        allocator_state_;
-    std::function<void()> call_requester_;
-    std::atomic<intptr_t> callbacks_outstanding_{
-        2};  // reserve for Finish and CompletionOp
-  };
-};
-
-template <class RequestType, class ResponseType>
-class CallbackClientStreamingHandler : public MethodHandler {
- public:
-  CallbackClientStreamingHandler(
-      std::function<
-          experimental::ServerReadReactor<RequestType, ResponseType>*()>
-          func)
-      : func_(std::move(func)) {}
-  void RunHandler(const HandlerParameter& param) final {
-    // Arena allocate a reader structure (that includes response)
-    g_core_codegen_interface->grpc_call_ref(param.call->call());
-
-    experimental::ServerReadReactor<RequestType, ResponseType>* reactor =
-        param.status.ok()
-            ? CatchingReactorCreator<
-                  experimental::ServerReadReactor<RequestType, ResponseType>>(
-                  func_)
-            : nullptr;
-
-    if (reactor == nullptr) {
-      // if deserialization or reactor creator failed, we need to fail the call
-      reactor = new UnimplementedReadReactor<RequestType, ResponseType>;
-    }
-
-    auto* reader = new (g_core_codegen_interface->grpc_call_arena_alloc(
-        param.call->call(), sizeof(ServerCallbackReaderImpl)))
-        ServerCallbackReaderImpl(param.server_context, param.call,
-                                 std::move(param.call_requester), reactor);
-
-    reader->BindReactor(reactor);
-    reactor->OnStarted(param.server_context, reader->response());
-    // The earliest that OnCancel can be called is after OnStarted is done.
-    reactor->MaybeCallOnCancel();
-    reader->MaybeDone();
-  }
-
- private:
-  std::function<experimental::ServerReadReactor<RequestType, ResponseType>*()>
-      func_;
-
-  class ServerCallbackReaderImpl
-      : public experimental::ServerCallbackReader<RequestType> {
-   public:
-    void Finish(Status s) override {
-      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
-                      &finish_ops_);
-      if (!ctx_->sent_initial_metadata_) {
-        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                        ctx_->initial_metadata_flags());
-        if (ctx_->compression_level_set()) {
-          finish_ops_.set_compression_level(ctx_->compression_level());
-        }
-        ctx_->sent_initial_metadata_ = true;
-      }
-      // The response is dropped if the status is not OK.
-      if (s.ok()) {
-        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
-                                     finish_ops_.SendMessagePtr(&resp_));
-      } else {
-        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
-      }
-      finish_ops_.set_core_cq_tag(&finish_tag_);
-      call_.PerformOps(&finish_ops_);
-    }
-
-    void SendInitialMetadata() override {
-      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      meta_tag_.Set(call_.call(),
-                    [this](bool ok) {
-                      reactor_->OnSendInitialMetadataDone(ok);
-                      MaybeDone();
-                    },
-                    &meta_ops_);
-      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                    ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        meta_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-      meta_ops_.set_core_cq_tag(&meta_tag_);
-      call_.PerformOps(&meta_ops_);
-    }
-
-    void Read(RequestType* req) override {
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      read_ops_.RecvMessage(req);
-      call_.PerformOps(&read_ops_);
-    }
-
-   private:
-    friend class CallbackClientStreamingHandler<RequestType, ResponseType>;
-
-    ServerCallbackReaderImpl(
-        ::grpc_impl::ServerContext* ctx, Call* call,
-        std::function<void()> call_requester,
-        experimental::ServerReadReactor<RequestType, ResponseType>* reactor)
-        : ctx_(ctx),
-          call_(*call),
-          call_requester_(std::move(call_requester)),
-          reactor_(reactor) {
-      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
-      read_tag_.Set(call_.call(),
-                    [this](bool ok) {
-                      reactor_->OnReadDone(ok);
-                      MaybeDone();
-                    },
-                    &read_ops_);
-      read_ops_.set_core_cq_tag(&read_tag_);
-    }
-
-    ~ServerCallbackReaderImpl() {}
-
-    ResponseType* response() { return &resp_; }
-
-    void MaybeDone() {
-      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                           1, std::memory_order_acq_rel) == 1)) {
-        reactor_->OnDone();
-        grpc_call* call = call_.call();
-        auto call_requester = std::move(call_requester_);
-        this->~ServerCallbackReaderImpl();  // explicitly call destructor
-        g_core_codegen_interface->grpc_call_unref(call);
-        call_requester();
-      }
-    }
-
-    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
-    CallbackWithSuccessTag meta_tag_;
-    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
-              CallOpServerSendStatus>
-        finish_ops_;
-    CallbackWithSuccessTag finish_tag_;
-    CallOpSet<CallOpRecvMessage<RequestType>> read_ops_;
-    CallbackWithSuccessTag read_tag_;
-
-    ::grpc_impl::ServerContext* ctx_;
-    Call call_;
-    ResponseType resp_;
-    std::function<void()> call_requester_;
-    experimental::ServerReadReactor<RequestType, ResponseType>* reactor_;
-    std::atomic<intptr_t> callbacks_outstanding_{
-        3};  // reserve for OnStarted, Finish, and CompletionOp
-  };
-};
-
-template <class RequestType, class ResponseType>
-class CallbackServerStreamingHandler : public MethodHandler {
- public:
-  CallbackServerStreamingHandler(
-      std::function<
-          experimental::ServerWriteReactor<RequestType, ResponseType>*()>
-          func)
-      : func_(std::move(func)) {}
-  void RunHandler(const HandlerParameter& param) final {
-    // Arena allocate a writer structure
-    g_core_codegen_interface->grpc_call_ref(param.call->call());
-
-    experimental::ServerWriteReactor<RequestType, ResponseType>* reactor =
-        param.status.ok()
-            ? CatchingReactorCreator<
-                  experimental::ServerWriteReactor<RequestType, ResponseType>>(
-                  func_)
-            : nullptr;
-
-    if (reactor == nullptr) {
-      // if deserialization or reactor creator failed, we need to fail the call
-      reactor = new UnimplementedWriteReactor<RequestType, ResponseType>;
-    }
-
-    auto* writer = new (g_core_codegen_interface->grpc_call_arena_alloc(
-        param.call->call(), sizeof(ServerCallbackWriterImpl)))
-        ServerCallbackWriterImpl(param.server_context, param.call,
-                                 static_cast<RequestType*>(param.request),
-                                 std::move(param.call_requester), reactor);
-    writer->BindReactor(reactor);
-    reactor->OnStarted(param.server_context, writer->request());
-    // The earliest that OnCancel can be called is after OnStarted is done.
-    reactor->MaybeCallOnCancel();
-    writer->MaybeDone();
-  }
-
-  void* Deserialize(grpc_call* call, grpc_byte_buffer* req, Status* status,
-                    void** handler_data) final {
-    ByteBuffer buf;
-    buf.set_buffer(req);
-    auto* request = new (g_core_codegen_interface->grpc_call_arena_alloc(
-        call, sizeof(RequestType))) RequestType();
-    *status = SerializationTraits<RequestType>::Deserialize(&buf, request);
-    buf.Release();
-    if (status->ok()) {
-      return request;
-    }
-    request->~RequestType();
-    return nullptr;
-  }
-
- private:
-  std::function<experimental::ServerWriteReactor<RequestType, ResponseType>*()>
-      func_;
-
-  class ServerCallbackWriterImpl
-      : public experimental::ServerCallbackWriter<ResponseType> {
-   public:
-    void Finish(Status s) override {
-      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
-                      &finish_ops_);
-      finish_ops_.set_core_cq_tag(&finish_tag_);
-
-      if (!ctx_->sent_initial_metadata_) {
-        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                        ctx_->initial_metadata_flags());
-        if (ctx_->compression_level_set()) {
-          finish_ops_.set_compression_level(ctx_->compression_level());
-        }
-        ctx_->sent_initial_metadata_ = true;
-      }
-      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
-      call_.PerformOps(&finish_ops_);
-    }
-
-    void SendInitialMetadata() override {
-      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      meta_tag_.Set(call_.call(),
-                    [this](bool ok) {
-                      reactor_->OnSendInitialMetadataDone(ok);
-                      MaybeDone();
-                    },
-                    &meta_ops_);
-      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                    ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        meta_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-      meta_ops_.set_core_cq_tag(&meta_tag_);
-      call_.PerformOps(&meta_ops_);
-    }
-
-    void Write(const ResponseType* resp, WriteOptions options) override {
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      if (options.is_last_message()) {
-        options.set_buffer_hint();
-      }
-      if (!ctx_->sent_initial_metadata_) {
-        write_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                       ctx_->initial_metadata_flags());
-        if (ctx_->compression_level_set()) {
-          write_ops_.set_compression_level(ctx_->compression_level());
-        }
-        ctx_->sent_initial_metadata_ = true;
-      }
-      // TODO(vjpai): don't assert
-      GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(resp, options).ok());
-      call_.PerformOps(&write_ops_);
-    }
-
-    void WriteAndFinish(const ResponseType* resp, WriteOptions options,
-                        Status s) override {
-      // This combines the write into the finish callback
-      // Don't send any message if the status is bad
-      if (s.ok()) {
-        // TODO(vjpai): don't assert
-        GPR_CODEGEN_ASSERT(finish_ops_.SendMessagePtr(resp, options).ok());
-      }
-      Finish(std::move(s));
-    }
-
-   private:
-    friend class CallbackServerStreamingHandler<RequestType, ResponseType>;
-
-    ServerCallbackWriterImpl(
-        ::grpc_impl::ServerContext* ctx, Call* call, const RequestType* req,
-        std::function<void()> call_requester,
-        experimental::ServerWriteReactor<RequestType, ResponseType>* reactor)
-        : ctx_(ctx),
-          call_(*call),
-          req_(req),
-          call_requester_(std::move(call_requester)),
-          reactor_(reactor) {
-      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
-      write_tag_.Set(call_.call(),
-                     [this](bool ok) {
-                       reactor_->OnWriteDone(ok);
-                       MaybeDone();
-                     },
-                     &write_ops_);
-      write_ops_.set_core_cq_tag(&write_tag_);
-    }
-    ~ServerCallbackWriterImpl() { req_->~RequestType(); }
-
-    const RequestType* request() { return req_; }
-
-    void MaybeDone() {
-      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                           1, std::memory_order_acq_rel) == 1)) {
-        reactor_->OnDone();
-        grpc_call* call = call_.call();
-        auto call_requester = std::move(call_requester_);
-        this->~ServerCallbackWriterImpl();  // explicitly call destructor
-        g_core_codegen_interface->grpc_call_unref(call);
-        call_requester();
-      }
-    }
-
-    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
-    CallbackWithSuccessTag meta_tag_;
-    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
-              CallOpServerSendStatus>
-        finish_ops_;
-    CallbackWithSuccessTag finish_tag_;
-    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage> write_ops_;
-    CallbackWithSuccessTag write_tag_;
-
-    ::grpc_impl::ServerContext* ctx_;
-    Call call_;
-    const RequestType* req_;
-    std::function<void()> call_requester_;
-    experimental::ServerWriteReactor<RequestType, ResponseType>* reactor_;
-    std::atomic<intptr_t> callbacks_outstanding_{
-        3};  // reserve for OnStarted, Finish, and CompletionOp
-  };
-};
-
-template <class RequestType, class ResponseType>
-class CallbackBidiHandler : public MethodHandler {
- public:
-  CallbackBidiHandler(
-      std::function<
-          experimental::ServerBidiReactor<RequestType, ResponseType>*()>
-          func)
-      : func_(std::move(func)) {}
-  void RunHandler(const HandlerParameter& param) final {
-    g_core_codegen_interface->grpc_call_ref(param.call->call());
-
-    experimental::ServerBidiReactor<RequestType, ResponseType>* reactor =
-        param.status.ok()
-            ? CatchingReactorCreator<
-                  experimental::ServerBidiReactor<RequestType, ResponseType>>(
-                  func_)
-            : nullptr;
-
-    if (reactor == nullptr) {
-      // if deserialization or reactor creator failed, we need to fail the call
-      reactor = new UnimplementedBidiReactor<RequestType, ResponseType>;
-    }
-
-    auto* stream = new (g_core_codegen_interface->grpc_call_arena_alloc(
-        param.call->call(), sizeof(ServerCallbackReaderWriterImpl)))
-        ServerCallbackReaderWriterImpl(param.server_context, param.call,
-                                       std::move(param.call_requester),
-                                       reactor);
-
-    stream->BindReactor(reactor);
-    reactor->OnStarted(param.server_context);
-    // The earliest that OnCancel can be called is after OnStarted is done.
-    reactor->MaybeCallOnCancel();
-    stream->MaybeDone();
-  }
-
- private:
-  std::function<experimental::ServerBidiReactor<RequestType, ResponseType>*()>
-      func_;
-
-  class ServerCallbackReaderWriterImpl
-      : public experimental::ServerCallbackReaderWriter<RequestType,
-                                                        ResponseType> {
-   public:
-    void Finish(Status s) override {
-      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
-                      &finish_ops_);
-      finish_ops_.set_core_cq_tag(&finish_tag_);
-
-      if (!ctx_->sent_initial_metadata_) {
-        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                        ctx_->initial_metadata_flags());
-        if (ctx_->compression_level_set()) {
-          finish_ops_.set_compression_level(ctx_->compression_level());
-        }
-        ctx_->sent_initial_metadata_ = true;
-      }
-      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
-      call_.PerformOps(&finish_ops_);
-    }
-
-    void SendInitialMetadata() override {
-      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      meta_tag_.Set(call_.call(),
-                    [this](bool ok) {
-                      reactor_->OnSendInitialMetadataDone(ok);
-                      MaybeDone();
-                    },
-                    &meta_ops_);
-      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                    ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        meta_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-      meta_ops_.set_core_cq_tag(&meta_tag_);
-      call_.PerformOps(&meta_ops_);
-    }
-
-    void Write(const ResponseType* resp, WriteOptions options) override {
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      if (options.is_last_message()) {
-        options.set_buffer_hint();
-      }
-      if (!ctx_->sent_initial_metadata_) {
-        write_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                       ctx_->initial_metadata_flags());
-        if (ctx_->compression_level_set()) {
-          write_ops_.set_compression_level(ctx_->compression_level());
-        }
-        ctx_->sent_initial_metadata_ = true;
-      }
-      // TODO(vjpai): don't assert
-      GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(resp, options).ok());
-      call_.PerformOps(&write_ops_);
-    }
-
-    void WriteAndFinish(const ResponseType* resp, WriteOptions options,
-                        Status s) override {
-      // Don't send any message if the status is bad
-      if (s.ok()) {
-        // TODO(vjpai): don't assert
-        GPR_CODEGEN_ASSERT(finish_ops_.SendMessagePtr(resp, options).ok());
-      }
-      Finish(std::move(s));
-    }
-
-    void Read(RequestType* req) override {
-      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
-      read_ops_.RecvMessage(req);
-      call_.PerformOps(&read_ops_);
-    }
-
-   private:
-    friend class CallbackBidiHandler<RequestType, ResponseType>;
-
-    ServerCallbackReaderWriterImpl(
-        ::grpc_impl::ServerContext* ctx, Call* call,
-        std::function<void()> call_requester,
-        experimental::ServerBidiReactor<RequestType, ResponseType>* reactor)
-        : ctx_(ctx),
-          call_(*call),
-          call_requester_(std::move(call_requester)),
-          reactor_(reactor) {
-      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
-      write_tag_.Set(call_.call(),
-                     [this](bool ok) {
-                       reactor_->OnWriteDone(ok);
-                       MaybeDone();
-                     },
-                     &write_ops_);
-      write_ops_.set_core_cq_tag(&write_tag_);
-      read_tag_.Set(call_.call(),
-                    [this](bool ok) {
-                      reactor_->OnReadDone(ok);
-                      MaybeDone();
-                    },
-                    &read_ops_);
-      read_ops_.set_core_cq_tag(&read_tag_);
-    }
-    ~ServerCallbackReaderWriterImpl() {}
-
-    void MaybeDone() {
-      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
-                           1, std::memory_order_acq_rel) == 1)) {
-        reactor_->OnDone();
-        grpc_call* call = call_.call();
-        auto call_requester = std::move(call_requester_);
-        this->~ServerCallbackReaderWriterImpl();  // explicitly call destructor
-        g_core_codegen_interface->grpc_call_unref(call);
-        call_requester();
-      }
-    }
-
-    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
-    CallbackWithSuccessTag meta_tag_;
-    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
-              CallOpServerSendStatus>
-        finish_ops_;
-    CallbackWithSuccessTag finish_tag_;
-    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage> write_ops_;
-    CallbackWithSuccessTag write_tag_;
-    CallOpSet<CallOpRecvMessage<RequestType>> read_ops_;
-    CallbackWithSuccessTag read_tag_;
-
-    ::grpc_impl::ServerContext* ctx_;
-    Call call_;
-    std::function<void()> call_requester_;
-    experimental::ServerBidiReactor<RequestType, ResponseType>* reactor_;
-    std::atomic<intptr_t> callbacks_outstanding_{
-        3};  // reserve for OnStarted, Finish, and CompletionOp
-  };
-};
-
-}  // namespace internal
-
 }  // namespace grpc
 
 #endif  // GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H

include/grpcpp/impl/codegen/server_callback_impl.h

@@ -0,0 +1,1186 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_IMPL_H
+#define GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_IMPL_H
+
+#include <atomic>
+#include <functional>
+#include <type_traits>
+
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/call_op_set.h>
+#include <grpcpp/impl/codegen/callback_common.h>
+#include <grpcpp/impl/codegen/config.h>
+#include <grpcpp/impl/codegen/core_codegen_interface.h>
+#include <grpcpp/impl/codegen/message_allocator.h>
+#include <grpcpp/impl/codegen/server_context_impl.h>
+#include <grpcpp/impl/codegen/server_interface.h>
+#include <grpcpp/impl/codegen/status.h>
+
+namespace grpc_impl {
+
+// Declare base class of all reactors as internal
+namespace internal {
+
+// Forward declarations
+template <class Request, class Response>
+class CallbackClientStreamingHandler;
+template <class Request, class Response>
+class CallbackServerStreamingHandler;
+template <class Request, class Response>
+class CallbackBidiHandler;
+
+class ServerReactor {
+ public:
+  virtual ~ServerReactor() = default;
+  virtual void OnDone() = 0;
+  virtual void OnCancel() = 0;
+
+ private:
+  friend class ::grpc_impl::ServerContext;
+  template <class Request, class Response>
+  friend class CallbackClientStreamingHandler;
+  template <class Request, class Response>
+  friend class CallbackServerStreamingHandler;
+  template <class Request, class Response>
+  friend class CallbackBidiHandler;
+
+  // The ServerReactor is responsible for tracking when it is safe to call
+  // OnCancel. This function should not be called until after OnStarted is done
+  // and the RPC has completed with a cancellation. This is tracked by counting
+  // how many of these conditions have been met and calling OnCancel when none
+  // remain unmet.
+
+  void MaybeCallOnCancel() {
+    if (GPR_UNLIKELY(on_cancel_conditions_remaining_.fetch_sub(
+                         1, std::memory_order_acq_rel) == 1)) {
+      OnCancel();
+    }
+  }
+
+  std::atomic<intptr_t> on_cancel_conditions_remaining_{2};
+};
+
+template <class Request, class Response>
+class DefaultMessageHolder
+    : public ::grpc::experimental::MessageHolder<Request, Response> {
+ public:
+  DefaultMessageHolder() {
+    this->set_request(&request_obj_);
+    this->set_response(&response_obj_);
+  }
+  void Release() override {
+    // the object is allocated in the call arena.
+    this->~DefaultMessageHolder<Request, Response>();
+  }
+
+ private:
+  Request request_obj_;
+  Response response_obj_;
+};
+
+}  // namespace internal
+
+namespace experimental {
+
+// Forward declarations
+template <class Request, class Response>
+class ServerReadReactor;
+template <class Request, class Response>
+class ServerWriteReactor;
+template <class Request, class Response>
+class ServerBidiReactor;
+
+// For unary RPCs, the exposed controller class is only an interface
+// and the actual implementation is an internal class.
+class ServerCallbackRpcController {
+ public:
+  virtual ~ServerCallbackRpcController() = default;
+
+  // The method handler must call this function when it is done so that
+  // the library knows to free its resources
+  virtual void Finish(::grpc::Status s) = 0;
+
+  // Allow the method handler to push out the initial metadata before
+  // the response and status are ready
+  virtual void SendInitialMetadata(std::function<void(bool)>) = 0;
+
+  /// SetCancelCallback passes in a callback to be called when the RPC is
+  /// canceled for whatever reason (streaming calls have OnCancel instead). This
+  /// is an advanced and uncommon use with several important restrictions. This
+  /// function may not be called more than once on the same RPC.
+  ///
+  /// If code calls SetCancelCallback on an RPC, it must also call
+  /// ClearCancelCallback before calling Finish on the RPC controller. That
+  /// method makes sure that no cancellation callback is executed for this RPC
+  /// beyond the point of its return. ClearCancelCallback may be called even if
+  /// SetCancelCallback was not called for this RPC, and it may be called
+  /// multiple times. It _must_ be called if SetCancelCallback was called for
+  /// this RPC.
+  ///
+  /// The callback should generally be lightweight and nonblocking and primarily
+  /// concerned with clearing application state related to the RPC or causing
+  /// operations (such as cancellations) to happen on dependent RPCs.
+  ///
+  /// If the RPC is already canceled at the time that SetCancelCallback is
+  /// called, the callback is invoked immediately.
+  ///
+  /// The cancellation callback may be executed concurrently with the method
+  /// handler that invokes it but will certainly not issue or execute after the
+  /// return of ClearCancelCallback. If ClearCancelCallback is invoked while the
+  /// callback is already executing, the callback will complete its execution
+  /// before ClearCancelCallback takes effect.
+  ///
+  /// To preserve the orderings described above, the callback may be called
+  /// under a lock that is also used for ClearCancelCallback and
+  /// ServerContext::IsCancelled, so the callback CANNOT call either of those
+  /// operations on this RPC or any other function that causes those operations
+  /// to be called before the callback completes.
+  virtual void SetCancelCallback(std::function<void()> callback) = 0;
+  virtual void ClearCancelCallback() = 0;
+
+  // NOTE: This is an API for advanced users who need custom allocators.
+  // Get and maybe mutate the allocator state associated with the current RPC.
+  virtual grpc::experimental::RpcAllocatorState* GetRpcAllocatorState() = 0;
+};
+
+// NOTE: The actual streaming object classes are provided
+// as API only to support mocking. There are no implementations of
+// these class interfaces in the API.
+template <class Request>
+class ServerCallbackReader {
+ public:
+  virtual ~ServerCallbackReader() {}
+  virtual void Finish(::grpc::Status s) = 0;
+  virtual void SendInitialMetadata() = 0;
+  virtual void Read(Request* msg) = 0;
+
+ protected:
+  template <class Response>
+  void BindReactor(ServerReadReactor<Request, Response>* reactor) {
+    reactor->InternalBindReader(this);
+  }
+};
+
+template <class Response>
+class ServerCallbackWriter {
+ public:
+  virtual ~ServerCallbackWriter() {}
+
+  virtual void Finish(::grpc::Status s) = 0;
+  virtual void SendInitialMetadata() = 0;
+  virtual void Write(const Response* msg, ::grpc::WriteOptions options) = 0;
+  virtual void WriteAndFinish(const Response* msg, ::grpc::WriteOptions options,
+                              ::grpc::Status s) {
+    // Default implementation that can/should be overridden
+    Write(msg, std::move(options));
+    Finish(std::move(s));
+  }
+
+ protected:
+  template <class Request>
+  void BindReactor(ServerWriteReactor<Request, Response>* reactor) {
+    reactor->InternalBindWriter(this);
+  }
+};
+
+template <class Request, class Response>
+class ServerCallbackReaderWriter {
+ public:
+  virtual ~ServerCallbackReaderWriter() {}
+
+  virtual void Finish(::grpc::Status s) = 0;
+  virtual void SendInitialMetadata() = 0;
+  virtual void Read(Request* msg) = 0;
+  virtual void Write(const Response* msg, ::grpc::WriteOptions options) = 0;
+  virtual void WriteAndFinish(const Response* msg, ::grpc::WriteOptions options,
+                              ::grpc::Status s) {
+    // Default implementation that can/should be overridden
+    Write(msg, std::move(options));
+    Finish(std::move(s));
+  }
+
+ protected:
+  void BindReactor(ServerBidiReactor<Request, Response>* reactor) {
+    reactor->InternalBindStream(this);
+  }
+};
+
+// The following classes are the reactor interfaces that are to be implemented
+// by the user, returned as the result of the method handler for a callback
+// method, and activated by the call to OnStarted. The library guarantees that
+// OnStarted will be called for any reactor that has been created using a
+// method handler registered on a service. No operation initiation method may be
+// called until after the call to OnStarted.
+// Note that none of the classes are pure; all reactions have a default empty
+// reaction so that the user class only needs to override those classes that it
+// cares about.
+
+/// \a ServerBidiReactor is the interface for a bidirectional streaming RPC.
+template <class Request, class Response>
+class ServerBidiReactor : public internal::ServerReactor {
+ public:
+  ~ServerBidiReactor() = default;
+
+  /// Do NOT call any operation initiation method (names that start with Start)
+  /// until after the library has called OnStarted on this object.
+
+  /// Send any initial metadata stored in the RPC context. If not invoked,
+  /// any initial metadata will be passed along with the first Write or the
+  /// Finish (if there are no writes).
+  void StartSendInitialMetadata() { stream_->SendInitialMetadata(); }
+
+  /// Initiate a read operation.
+  ///
+  /// \param[out] req Where to eventually store the read message. Valid when
+  ///                 the library calls OnReadDone
+  void StartRead(Request* req) { stream_->Read(req); }
+
+  /// Initiate a write operation.
+  ///
+  /// \param[in] resp The message to be written. The library takes temporary
+  ///                 ownership until OnWriteDone, at which point the
+  ///                 application regains ownership of resp.
+  void StartWrite(const Response* resp) {
+    StartWrite(resp, ::grpc::WriteOptions());
+  }
+
+  /// Initiate a write operation with specified options.
+  ///
+  /// \param[in] resp The message to be written. The library takes temporary
+  ///                 ownership until OnWriteDone, at which point the
+  ///                 application regains ownership of resp.
+  /// \param[in] options The WriteOptions to use for writing this message
+  void StartWrite(const Response* resp, ::grpc::WriteOptions options) {
+    stream_->Write(resp, std::move(options));
+  }
+
+  /// Initiate a write operation with specified options and final RPC Status,
+  /// which also causes any trailing metadata for this RPC to be sent out.
+  /// StartWriteAndFinish is like merging StartWriteLast and Finish into a
+  /// single step. A key difference, though, is that this operation doesn't have
+  /// an OnWriteDone reaction - it is considered complete only when OnDone is
+  /// available. An RPC can either have StartWriteAndFinish or Finish, but not
+  /// both.
+  ///
+  /// \param[in] resp The message to be written. The library takes temporary
+  ///                 ownership until Onone, at which point the application
+  ///                 regains ownership of resp.
+  /// \param[in] options The WriteOptions to use for writing this message
+  /// \param[in] s The status outcome of this RPC
+  void StartWriteAndFinish(const Response* resp, ::grpc::WriteOptions options,
+                           ::grpc::Status s) {
+    stream_->WriteAndFinish(resp, std::move(options), std::move(s));
+  }
+
+  /// Inform system of a planned write operation with specified options, but
+  /// allow the library to schedule the actual write coalesced with the writing
+  /// of trailing metadata (which takes place on a Finish call).
+  ///
+  /// \param[in] resp The message to be written. The library takes temporary
+  ///                 ownership until OnWriteDone, at which point the
+  ///                 application regains ownership of resp.
+  /// \param[in] options The WriteOptions to use for writing this message
+  void StartWriteLast(const Response* resp, ::grpc::WriteOptions options) {
+    StartWrite(resp, std::move(options.set_last_message()));
+  }
+
+  /// Indicate that the stream is to be finished and the trailing metadata and
+  /// RPC status are to be sent. Every RPC MUST be finished using either Finish
+  /// or StartWriteAndFinish (but not both), even if the RPC is already
+  /// cancelled.
+  ///
+  /// \param[in] s The status outcome of this RPC
+  void Finish(::grpc::Status s) { stream_->Finish(std::move(s)); }
+
+  /// Notify the application that a streaming RPC has started and that it is now
+  /// ok to call any operation initiation method. An RPC is considered started
+  /// after the server has received all initial metadata from the client, which
+  /// is a result of the client calling StartCall().
+  ///
+  /// \param[in] context The context object now associated with this RPC
+  virtual void OnStarted(::grpc_impl::ServerContext* context) {}
+
+  /// Notifies the application that an explicit StartSendInitialMetadata
+  /// operation completed. Not used when the sending of initial metadata
+  /// piggybacks onto the first write.
+  ///
+  /// \param[in] ok Was it successful? If false, no further write-side operation
+  ///               will succeed.
+  virtual void OnSendInitialMetadataDone(bool ok) {}
+
+  /// Notifies the application that a StartRead operation completed.
+  ///
+  /// \param[in] ok Was it successful? If false, no further read-side operation
+  ///               will succeed.
+  virtual void OnReadDone(bool ok) {}
+
+  /// Notifies the application that a StartWrite (or StartWriteLast) operation
+  /// completed.
+  ///
+  /// \param[in] ok Was it successful? If false, no further write-side operation
+  ///               will succeed.
+  virtual void OnWriteDone(bool ok) {}
+
+  /// Notifies the application that all operations associated with this RPC
+  /// have completed. This is an override (from the internal base class) but not
+  /// final, so derived classes should override it if they want to take action.
+  void OnDone() override {}
+
+  /// Notifies the application that this RPC has been cancelled. This is an
+  /// override (from the internal base class) but not final, so derived classes
+  /// should override it if they want to take action.
+  void OnCancel() override {}
+
+ private:
+  friend class ServerCallbackReaderWriter<Request, Response>;
+  // May be overridden by internal implementation details. This is not a public
+  // customization point.
+  virtual void InternalBindStream(
+      ServerCallbackReaderWriter<Request, Response>* stream) {
+    stream_ = stream;
+  }
+
+  ServerCallbackReaderWriter<Request, Response>* stream_;
+};
+
+/// \a ServerReadReactor is the interface for a client-streaming RPC.
+template <class Request, class Response>
+class ServerReadReactor : public internal::ServerReactor {
+ public:
+  ~ServerReadReactor() = default;
+
+  /// The following operation initiations are exactly like ServerBidiReactor.
+  void StartSendInitialMetadata() { reader_->SendInitialMetadata(); }
+  void StartRead(Request* req) { reader_->Read(req); }
+  void Finish(::grpc::Status s) { reader_->Finish(std::move(s)); }
+
+  /// Similar to ServerBidiReactor::OnStarted, except that this also provides
+  /// the response object that the stream fills in before calling Finish.
+  /// (It must be filled in if status is OK, but it may be filled in otherwise.)
+  ///
+  /// \param[in] context The context object now associated with this RPC
+  /// \param[in] resp The response object to be used by this RPC
+  virtual void OnStarted(::grpc_impl::ServerContext* context, Response* resp) {}
+
+  /// The following notifications are exactly like ServerBidiReactor.
+  virtual void OnSendInitialMetadataDone(bool ok) {}
+  virtual void OnReadDone(bool ok) {}
+  void OnDone() override {}
+  void OnCancel() override {}
+
+ private:
+  friend class ServerCallbackReader<Request>;
+  // May be overridden by internal implementation details. This is not a public
+  // customization point.
+  virtual void InternalBindReader(ServerCallbackReader<Request>* reader) {
+    reader_ = reader;
+  }
+
+  ServerCallbackReader<Request>* reader_;
+};
+
+/// \a ServerWriteReactor is the interface for a server-streaming RPC.
+template <class Request, class Response>
+class ServerWriteReactor : public internal::ServerReactor {
+ public:
+  ~ServerWriteReactor() = default;
+
+  /// The following operation initiations are exactly like ServerBidiReactor.
+  void StartSendInitialMetadata() { writer_->SendInitialMetadata(); }
+  void StartWrite(const Response* resp) {
+    StartWrite(resp, ::grpc::WriteOptions());
+  }
+  void StartWrite(const Response* resp, ::grpc::WriteOptions options) {
+    writer_->Write(resp, std::move(options));
+  }
+  void StartWriteAndFinish(const Response* resp, ::grpc::WriteOptions options,
+                           ::grpc::Status s) {
+    writer_->WriteAndFinish(resp, std::move(options), std::move(s));
+  }
+  void StartWriteLast(const Response* resp, ::grpc::WriteOptions options) {
+    StartWrite(resp, std::move(options.set_last_message()));
+  }
+  void Finish(::grpc::Status s) { writer_->Finish(std::move(s)); }
+
+  /// Similar to ServerBidiReactor::OnStarted, except that this also provides
+  /// the request object sent by the client.
+  ///
+  /// \param[in] context The context object now associated with this RPC
+  /// \param[in] req The request object sent by the client
+  virtual void OnStarted(::grpc_impl::ServerContext* context,
+                         const Request* req) {}
+
+  /// The following notifications are exactly like ServerBidiReactor.
+  virtual void OnSendInitialMetadataDone(bool ok) {}
+  virtual void OnWriteDone(bool ok) {}
+  void OnDone() override {}
+  void OnCancel() override {}
+
+ private:
+  friend class ServerCallbackWriter<Response>;
+  // May be overridden by internal implementation details. This is not a public
+  // customization point.
+  virtual void InternalBindWriter(ServerCallbackWriter<Response>* writer) {
+    writer_ = writer;
+  }
+
+  ServerCallbackWriter<Response>* writer_;
+};
+
+}  // namespace experimental
+
+namespace internal {
+
+template <class Request, class Response>
+class UnimplementedReadReactor
+    : public experimental::ServerReadReactor<Request, Response> {
+ public:
+  void OnDone() override { delete this; }
+  void OnStarted(::grpc_impl::ServerContext*, Response*) override {
+    this->Finish(::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, ""));
+  }
+};
+
+template <class Request, class Response>
+class UnimplementedWriteReactor
+    : public experimental::ServerWriteReactor<Request, Response> {
+ public:
+  void OnDone() override { delete this; }
+  void OnStarted(::grpc_impl::ServerContext*, const Request*) override {
+    this->Finish(::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, ""));
+  }
+};
+
+template <class Request, class Response>
+class UnimplementedBidiReactor
+    : public experimental::ServerBidiReactor<Request, Response> {
+ public:
+  void OnDone() override { delete this; }
+  void OnStarted(::grpc_impl::ServerContext*) override {
+    this->Finish(::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, ""));
+  }
+};
+
+template <class RequestType, class ResponseType>
+class CallbackUnaryHandler : public grpc::internal::MethodHandler {
+ public:
+  CallbackUnaryHandler(
+      std::function<void(::grpc_impl::ServerContext*, const RequestType*,
+                         ResponseType*,
+                         experimental::ServerCallbackRpcController*)>
+          func)
+      : func_(func) {}
+
+  void SetMessageAllocator(
+      ::grpc::experimental::MessageAllocator<RequestType, ResponseType>*
+          allocator) {
+    allocator_ = allocator;
+  }
+
+  void RunHandler(const HandlerParameter& param) final {
+    // Arena allocate a controller structure (that includes request/response)
+    ::grpc::g_core_codegen_interface->grpc_call_ref(param.call->call());
+    auto* allocator_state = static_cast<
+        grpc::experimental::MessageHolder<RequestType, ResponseType>*>(
+        param.internal_data);
+    auto* controller =
+        new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+            param.call->call(), sizeof(ServerCallbackRpcControllerImpl)))
+            ServerCallbackRpcControllerImpl(param.server_context, param.call,
+                                            allocator_state,
+                                            std::move(param.call_requester));
+    ::grpc::Status status = param.status;
+    if (status.ok()) {
+      // Call the actual function handler and expect the user to call finish
+      grpc::internal::CatchingCallback(func_, param.server_context,
+                                       controller->request(),
+                                       controller->response(), controller);
+    } else {
+      // if deserialization failed, we need to fail the call
+      controller->Finish(status);
+    }
+  }
+
+  void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                    ::grpc::Status* status, void** handler_data) final {
+    grpc::ByteBuffer buf;
+    buf.set_buffer(req);
+    RequestType* request = nullptr;
+    ::grpc::experimental::MessageHolder<RequestType, ResponseType>*
+        allocator_state = nullptr;
+    if (allocator_ != nullptr) {
+      allocator_state = allocator_->AllocateMessages();
+    } else {
+      allocator_state =
+          new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+              call, sizeof(DefaultMessageHolder<RequestType, ResponseType>)))
+              DefaultMessageHolder<RequestType, ResponseType>();
+    }
+    *handler_data = allocator_state;
+    request = allocator_state->request();
+    *status =
+        ::grpc::SerializationTraits<RequestType>::Deserialize(&buf, request);
+    buf.Release();
+    if (status->ok()) {
+      return request;
+    }
+    // Clean up on deserialization failure.
+    allocator_state->Release();
+    return nullptr;
+  }
+
+ private:
+  std::function<void(::grpc_impl::ServerContext*, const RequestType*,
+                     ResponseType*, experimental::ServerCallbackRpcController*)>
+      func_;
+  grpc::experimental::MessageAllocator<RequestType, ResponseType>* allocator_ =
+      nullptr;
+
+  // The implementation class of ServerCallbackRpcController is a private member
+  // of CallbackUnaryHandler since it is never exposed anywhere, and this allows
+  // it to take advantage of CallbackUnaryHandler's friendships.
+  class ServerCallbackRpcControllerImpl
+      : public experimental::ServerCallbackRpcController {
+   public:
+    void Finish(::grpc::Status s) override {
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
+      if (!ctx_->sent_initial_metadata_) {
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // The response is dropped if the status is not OK.
+      if (s.ok()) {
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
+                                     finish_ops_.SendMessagePtr(response()));
+      } else {
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      }
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+      call_.PerformOps(&finish_ops_);
+    }
+
+    void SendInitialMetadata(std::function<void(bool)> f) override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      // TODO(vjpai): Consider taking f as a move-capture if we adopt C++14
+      //              and if performance of this operation matters
+      meta_tag_.Set(call_.call(),
+                    [this, f](bool ok) {
+                      f(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
+    }
+
+    // Neither SetCancelCallback nor ClearCancelCallback should affect the
+    // callbacks_outstanding_ count since they are paired and both must precede
+    // the invocation of Finish (if they are used at all)
+    void SetCancelCallback(std::function<void()> callback) override {
+      ctx_->SetCancelCallback(std::move(callback));
+    }
+
+    void ClearCancelCallback() override { ctx_->ClearCancelCallback(); }
+
+    grpc::experimental::RpcAllocatorState* GetRpcAllocatorState() override {
+      return allocator_state_;
+    }
+
+   private:
+    friend class CallbackUnaryHandler<RequestType, ResponseType>;
+
+    ServerCallbackRpcControllerImpl(
+        ServerContext* ctx, ::grpc::internal::Call* call,
+        ::grpc::experimental::MessageHolder<RequestType, ResponseType>*
+            allocator_state,
+        std::function<void()> call_requester)
+        : ctx_(ctx),
+          call_(*call),
+          allocator_state_(allocator_state),
+          call_requester_(std::move(call_requester)) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, nullptr);
+    }
+
+    const RequestType* request() { return allocator_state_->request(); }
+    ResponseType* response() { return allocator_state_->response(); }
+
+    void MaybeDone() {
+      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                           1, std::memory_order_acq_rel) == 1)) {
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        allocator_state_->Release();
+        this->~ServerCallbackRpcControllerImpl();  // explicitly call destructor
+        ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata>
+        meta_ops_;
+    grpc::internal::CallbackWithSuccessTag meta_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                              grpc::internal::CallOpSendMessage,
+                              grpc::internal::CallOpServerSendStatus>
+        finish_ops_;
+    grpc::internal::CallbackWithSuccessTag finish_tag_;
+
+    ::grpc_impl::ServerContext* ctx_;
+    grpc::internal::Call call_;
+    grpc::experimental::MessageHolder<RequestType, ResponseType>* const
+        allocator_state_;
+    std::function<void()> call_requester_;
+    std::atomic<intptr_t> callbacks_outstanding_{
+        2};  // reserve for Finish and CompletionOp
+  };
+};
+
+template <class RequestType, class ResponseType>
+class CallbackClientStreamingHandler : public grpc::internal::MethodHandler {
+ public:
+  CallbackClientStreamingHandler(
+      std::function<
+          experimental::ServerReadReactor<RequestType, ResponseType>*()>
+          func)
+      : func_(std::move(func)) {}
+  void RunHandler(const HandlerParameter& param) final {
+    // Arena allocate a reader structure (that includes response)
+    ::grpc::g_core_codegen_interface->grpc_call_ref(param.call->call());
+
+    experimental::ServerReadReactor<RequestType, ResponseType>* reactor =
+        param.status.ok()
+            ? ::grpc::internal::CatchingReactorCreator<
+                  experimental::ServerReadReactor<RequestType, ResponseType>>(
+                  func_)
+            : nullptr;
+
+    if (reactor == nullptr) {
+      // if deserialization or reactor creator failed, we need to fail the call
+      reactor = new UnimplementedReadReactor<RequestType, ResponseType>;
+    }
+
+    auto* reader = new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        param.call->call(), sizeof(ServerCallbackReaderImpl)))
+        ServerCallbackReaderImpl(param.server_context, param.call,
+                                 std::move(param.call_requester), reactor);
+
+    reader->BindReactor(reactor);
+    reactor->OnStarted(param.server_context, reader->response());
+    // The earliest that OnCancel can be called is after OnStarted is done.
+    reactor->MaybeCallOnCancel();
+    reader->MaybeDone();
+  }
+
+ private:
+  std::function<experimental::ServerReadReactor<RequestType, ResponseType>*()>
+      func_;
+
+  class ServerCallbackReaderImpl
+      : public experimental::ServerCallbackReader<RequestType> {
+   public:
+    void Finish(::grpc::Status s) override {
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
+      if (!ctx_->sent_initial_metadata_) {
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // The response is dropped if the status is not OK.
+      if (s.ok()) {
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
+                                     finish_ops_.SendMessagePtr(&resp_));
+      } else {
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      }
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+      call_.PerformOps(&finish_ops_);
+    }
+
+    void SendInitialMetadata() override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      meta_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnSendInitialMetadataDone(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
+    }
+
+    void Read(RequestType* req) override {
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      read_ops_.RecvMessage(req);
+      call_.PerformOps(&read_ops_);
+    }
+
+   private:
+    friend class CallbackClientStreamingHandler<RequestType, ResponseType>;
+
+    ServerCallbackReaderImpl(
+        ::grpc_impl::ServerContext* ctx, grpc::internal::Call* call,
+        std::function<void()> call_requester,
+        experimental::ServerReadReactor<RequestType, ResponseType>* reactor)
+        : ctx_(ctx),
+          call_(*call),
+          call_requester_(std::move(call_requester)),
+          reactor_(reactor) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
+      read_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnReadDone(ok);
+                      MaybeDone();
+                    },
+                    &read_ops_);
+      read_ops_.set_core_cq_tag(&read_tag_);
+    }
+
+    ~ServerCallbackReaderImpl() {}
+
+    ResponseType* response() { return &resp_; }
+
+    void MaybeDone() {
+      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                           1, std::memory_order_acq_rel) == 1)) {
+        reactor_->OnDone();
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        this->~ServerCallbackReaderImpl();  // explicitly call destructor
+        ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata>
+        meta_ops_;
+    grpc::internal::CallbackWithSuccessTag meta_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                              grpc::internal::CallOpSendMessage,
+                              grpc::internal::CallOpServerSendStatus>
+        finish_ops_;
+    grpc::internal::CallbackWithSuccessTag finish_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpRecvMessage<RequestType>>
+        read_ops_;
+    grpc::internal::CallbackWithSuccessTag read_tag_;
+
+    ::grpc_impl::ServerContext* ctx_;
+    grpc::internal::Call call_;
+    ResponseType resp_;
+    std::function<void()> call_requester_;
+    experimental::ServerReadReactor<RequestType, ResponseType>* reactor_;
+    std::atomic<intptr_t> callbacks_outstanding_{
+        3};  // reserve for OnStarted, Finish, and CompletionOp
+  };
+};
+
+template <class RequestType, class ResponseType>
+class CallbackServerStreamingHandler : public grpc::internal::MethodHandler {
+ public:
+  CallbackServerStreamingHandler(
+      std::function<
+          experimental::ServerWriteReactor<RequestType, ResponseType>*()>
+          func)
+      : func_(std::move(func)) {}
+  void RunHandler(const HandlerParameter& param) final {
+    // Arena allocate a writer structure
+    ::grpc::g_core_codegen_interface->grpc_call_ref(param.call->call());
+
+    experimental::ServerWriteReactor<RequestType, ResponseType>* reactor =
+        param.status.ok()
+            ? ::grpc::internal::CatchingReactorCreator<
+                  experimental::ServerWriteReactor<RequestType, ResponseType>>(
+                  func_)
+            : nullptr;
+
+    if (reactor == nullptr) {
+      // if deserialization or reactor creator failed, we need to fail the call
+      reactor = new UnimplementedWriteReactor<RequestType, ResponseType>;
+    }
+
+    auto* writer = new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        param.call->call(), sizeof(ServerCallbackWriterImpl)))
+        ServerCallbackWriterImpl(param.server_context, param.call,
+                                 static_cast<RequestType*>(param.request),
+                                 std::move(param.call_requester), reactor);
+    writer->BindReactor(reactor);
+    reactor->OnStarted(param.server_context, writer->request());
+    // The earliest that OnCancel can be called is after OnStarted is done.
+    reactor->MaybeCallOnCancel();
+    writer->MaybeDone();
+  }
+
+  void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                    ::grpc::Status* status, void** handler_data) final {
+    ::grpc::ByteBuffer buf;
+    buf.set_buffer(req);
+    auto* request =
+        new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+            call, sizeof(RequestType))) RequestType();
+    *status =
+        ::grpc::SerializationTraits<RequestType>::Deserialize(&buf, request);
+    buf.Release();
+    if (status->ok()) {
+      return request;
+    }
+    request->~RequestType();
+    return nullptr;
+  }
+
+ private:
+  std::function<experimental::ServerWriteReactor<RequestType, ResponseType>*()>
+      func_;
+
+  class ServerCallbackWriterImpl
+      : public experimental::ServerCallbackWriter<ResponseType> {
+   public:
+    void Finish(::grpc::Status s) override {
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+
+      if (!ctx_->sent_initial_metadata_) {
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      call_.PerformOps(&finish_ops_);
+    }
+
+    void SendInitialMetadata() override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      meta_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnSendInitialMetadataDone(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
+    }
+
+    void Write(const ResponseType* resp,
+               ::grpc::WriteOptions options) override {
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      if (options.is_last_message()) {
+        options.set_buffer_hint();
+      }
+      if (!ctx_->sent_initial_metadata_) {
+        write_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                       ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          write_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // TODO(vjpai): don't assert
+      GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(resp, options).ok());
+      call_.PerformOps(&write_ops_);
+    }
+
+    void WriteAndFinish(const ResponseType* resp, ::grpc::WriteOptions options,
+                        ::grpc::Status s) override {
+      // This combines the write into the finish callback
+      // Don't send any message if the status is bad
+      if (s.ok()) {
+        // TODO(vjpai): don't assert
+        GPR_CODEGEN_ASSERT(finish_ops_.SendMessagePtr(resp, options).ok());
+      }
+      Finish(std::move(s));
+    }
+
+   private:
+    friend class CallbackServerStreamingHandler<RequestType, ResponseType>;
+
+    ServerCallbackWriterImpl(
+        ::grpc_impl::ServerContext* ctx, grpc::internal::Call* call,
+        const RequestType* req, std::function<void()> call_requester,
+        experimental::ServerWriteReactor<RequestType, ResponseType>* reactor)
+        : ctx_(ctx),
+          call_(*call),
+          req_(req),
+          call_requester_(std::move(call_requester)),
+          reactor_(reactor) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
+      write_tag_.Set(call_.call(),
+                     [this](bool ok) {
+                       reactor_->OnWriteDone(ok);
+                       MaybeDone();
+                     },
+                     &write_ops_);
+      write_ops_.set_core_cq_tag(&write_tag_);
+    }
+    ~ServerCallbackWriterImpl() { req_->~RequestType(); }
+
+    const RequestType* request() { return req_; }
+
+    void MaybeDone() {
+      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                           1, std::memory_order_acq_rel) == 1)) {
+        reactor_->OnDone();
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        this->~ServerCallbackWriterImpl();  // explicitly call destructor
+        ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata>
+        meta_ops_;
+    grpc::internal::CallbackWithSuccessTag meta_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                              grpc::internal::CallOpSendMessage,
+                              grpc::internal::CallOpServerSendStatus>
+        finish_ops_;
+    grpc::internal::CallbackWithSuccessTag finish_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                              grpc::internal::CallOpSendMessage>
+        write_ops_;
+    grpc::internal::CallbackWithSuccessTag write_tag_;
+
+    ::grpc_impl::ServerContext* ctx_;
+    grpc::internal::Call call_;
+    const RequestType* req_;
+    std::function<void()> call_requester_;
+    experimental::ServerWriteReactor<RequestType, ResponseType>* reactor_;
+    std::atomic<intptr_t> callbacks_outstanding_{
+        3};  // reserve for OnStarted, Finish, and CompletionOp
+  };
+};
+
+template <class RequestType, class ResponseType>
+class CallbackBidiHandler : public grpc::internal::MethodHandler {
+ public:
+  CallbackBidiHandler(
+      std::function<
+          experimental::ServerBidiReactor<RequestType, ResponseType>*()>
+          func)
+      : func_(std::move(func)) {}
+  void RunHandler(const HandlerParameter& param) final {
+    ::grpc::g_core_codegen_interface->grpc_call_ref(param.call->call());
+
+    experimental::ServerBidiReactor<RequestType, ResponseType>* reactor =
+        param.status.ok()
+            ? ::grpc::internal::CatchingReactorCreator<
+                  experimental::ServerBidiReactor<RequestType, ResponseType>>(
+                  func_)
+            : nullptr;
+
+    if (reactor == nullptr) {
+      // if deserialization or reactor creator failed, we need to fail the call
+      reactor = new UnimplementedBidiReactor<RequestType, ResponseType>;
+    }
+
+    auto* stream = new (::grpc::g_core_codegen_interface->grpc_call_arena_alloc(
+        param.call->call(), sizeof(ServerCallbackReaderWriterImpl)))
+        ServerCallbackReaderWriterImpl(param.server_context, param.call,
+                                       std::move(param.call_requester),
+                                       reactor);
+
+    stream->BindReactor(reactor);
+    reactor->OnStarted(param.server_context);
+    // The earliest that OnCancel can be called is after OnStarted is done.
+    reactor->MaybeCallOnCancel();
+    stream->MaybeDone();
+  }
+
+ private:
+  std::function<experimental::ServerBidiReactor<RequestType, ResponseType>*()>
+      func_;
+
+  class ServerCallbackReaderWriterImpl
+      : public experimental::ServerCallbackReaderWriter<RequestType,
+                                                        ResponseType> {
+   public:
+    void Finish(::grpc::Status s) override {
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+
+      if (!ctx_->sent_initial_metadata_) {
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      call_.PerformOps(&finish_ops_);
+    }
+
+    void SendInitialMetadata() override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      meta_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnSendInitialMetadataDone(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
+    }
+
+    void Write(const ResponseType* resp,
+               ::grpc::WriteOptions options) override {
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      if (options.is_last_message()) {
+        options.set_buffer_hint();
+      }
+      if (!ctx_->sent_initial_metadata_) {
+        write_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                       ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          write_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // TODO(vjpai): don't assert
+      GPR_CODEGEN_ASSERT(write_ops_.SendMessagePtr(resp, options).ok());
+      call_.PerformOps(&write_ops_);
+    }
+
+    void WriteAndFinish(const ResponseType* resp, ::grpc::WriteOptions options,
+                        ::grpc::Status s) override {
+      // Don't send any message if the status is bad
+      if (s.ok()) {
+        // TODO(vjpai): don't assert
+        GPR_CODEGEN_ASSERT(finish_ops_.SendMessagePtr(resp, options).ok());
+      }
+      Finish(std::move(s));
+    }
+
+    void Read(RequestType* req) override {
+      callbacks_outstanding_.fetch_add(1, std::memory_order_relaxed);
+      read_ops_.RecvMessage(req);
+      call_.PerformOps(&read_ops_);
+    }
+
+   private:
+    friend class CallbackBidiHandler<RequestType, ResponseType>;
+
+    ServerCallbackReaderWriterImpl(
+        ::grpc_impl::ServerContext* ctx, grpc::internal::Call* call,
+        std::function<void()> call_requester,
+        experimental::ServerBidiReactor<RequestType, ResponseType>* reactor)
+        : ctx_(ctx),
+          call_(*call),
+          call_requester_(std::move(call_requester)),
+          reactor_(reactor) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
+      write_tag_.Set(call_.call(),
+                     [this](bool ok) {
+                       reactor_->OnWriteDone(ok);
+                       MaybeDone();
+                     },
+                     &write_ops_);
+      write_ops_.set_core_cq_tag(&write_tag_);
+      read_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnReadDone(ok);
+                      MaybeDone();
+                    },
+                    &read_ops_);
+      read_ops_.set_core_cq_tag(&read_tag_);
+    }
+    ~ServerCallbackReaderWriterImpl() {}
+
+    void MaybeDone() {
+      if (GPR_UNLIKELY(callbacks_outstanding_.fetch_sub(
+                           1, std::memory_order_acq_rel) == 1)) {
+        reactor_->OnDone();
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        this->~ServerCallbackReaderWriterImpl();  // explicitly call destructor
+        ::grpc::g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata>
+        meta_ops_;
+    grpc::internal::CallbackWithSuccessTag meta_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                              grpc::internal::CallOpSendMessage,
+                              grpc::internal::CallOpServerSendStatus>
+        finish_ops_;
+    grpc::internal::CallbackWithSuccessTag finish_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata,
+                              grpc::internal::CallOpSendMessage>
+        write_ops_;
+    grpc::internal::CallbackWithSuccessTag write_tag_;
+    grpc::internal::CallOpSet<grpc::internal::CallOpRecvMessage<RequestType>>
+        read_ops_;
+    grpc::internal::CallbackWithSuccessTag read_tag_;
+
+    ::grpc_impl::ServerContext* ctx_;
+    grpc::internal::Call call_;
+    std::function<void()> call_requester_;
+    experimental::ServerBidiReactor<RequestType, ResponseType>* reactor_;
+    std::atomic<intptr_t> callbacks_outstanding_{
+        3};  // reserve for OnStarted, Finish, and CompletionOp
+  };
+};
+
+}  // namespace internal
+
+}  // namespace grpc_impl
+
+#endif  // GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_IMPL_H

include/grpcpp/impl/codegen/server_context_impl.h

@@ -44,10 +44,6 @@ namespace grpc_impl {
 class ClientContext;
 class CompletionQueue;
 class Server;
-}  // namespace grpc_impl
-namespace grpc {
-class GenericServerContext;
-class ServerInterface;
 template <class W, class R>
 class ServerAsyncReader;
 template <class W>
@@ -62,14 +58,6 @@ template <class W>
 class ServerWriter;
 
 namespace internal {
-template <class W, class R>
-class ServerReaderWriterBody;
-template <class ServiceType, class RequestType, class ResponseType>
-class RpcMethodHandler;
-template <class ServiceType, class RequestType, class ResponseType>
-class ClientStreamingHandler;
-template <class ServiceType, class RequestType, class ResponseType>
-class ServerStreamingHandler;
 template <class ServiceType, class RequestType, class ResponseType>
 class BidiStreamingHandler;
 template <class RequestType, class ResponseType>
@@ -80,12 +68,28 @@ template <class RequestType, class ResponseType>
 class CallbackServerStreamingHandler;
 template <class RequestType, class ResponseType>
 class CallbackBidiHandler;
+template <class W, class R>
+class ServerReaderWriterBody;
+class ServerReactor;
+}  // namespace internal
+
+}  // namespace grpc_impl
+namespace grpc {
+class GenericServerContext;
+class ServerInterface;
+
+namespace internal {
+template <class ServiceType, class RequestType, class ResponseType>
+class ClientStreamingHandler;
+template <class ServiceType, class RequestType, class ResponseType>
+class ServerStreamingHandler;
+template <class ServiceType, class RequestType, class ResponseType>
+class RpcMethodHandler;
 template <class Streamer, bool WriteNeeded>
 class TemplatedBidiStreamingHandler;
 template <StatusCode code>
 class ErrorMethodHandler;
 class Call;
-class ServerReactor;
 }  // namespace internal
 
 class ServerInterface;
@@ -275,19 +279,19 @@ class ServerContext {
   friend class ::grpc::ServerInterface;
   friend class ::grpc_impl::Server;
   template <class W, class R>
-  friend class ::grpc::ServerAsyncReader;
+  friend class ::grpc_impl::ServerAsyncReader;
   template <class W>
-  friend class ::grpc::ServerAsyncWriter;
+  friend class ::grpc_impl::ServerAsyncWriter;
   template <class W>
-  friend class ::grpc::ServerAsyncResponseWriter;
+  friend class ::grpc_impl::ServerAsyncResponseWriter;
   template <class W, class R>
-  friend class ::grpc::ServerAsyncReaderWriter;
+  friend class ::grpc_impl::ServerAsyncReaderWriter;
   template <class R>
-  friend class ::grpc::ServerReader;
+  friend class ::grpc_impl::ServerReader;
   template <class W>
-  friend class ::grpc::ServerWriter;
+  friend class ::grpc_impl::ServerWriter;
   template <class W, class R>
-  friend class ::grpc::internal::ServerReaderWriterBody;
+  friend class ::grpc_impl::internal::ServerReaderWriterBody;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class ::grpc::internal::RpcMethodHandler;
   template <class ServiceType, class RequestType, class ResponseType>
@@ -297,13 +301,13 @@ class ServerContext {
   template <class Streamer, bool WriteNeeded>
   friend class ::grpc::internal::TemplatedBidiStreamingHandler;
   template <class RequestType, class ResponseType>
-  friend class ::grpc::internal::CallbackUnaryHandler;
+  friend class ::grpc_impl::internal::CallbackUnaryHandler;
   template <class RequestType, class ResponseType>
-  friend class ::grpc::internal::CallbackClientStreamingHandler;
+  friend class ::grpc_impl::internal::CallbackClientStreamingHandler;
   template <class RequestType, class ResponseType>
-  friend class ::grpc::internal::CallbackServerStreamingHandler;
+  friend class ::grpc_impl::internal::CallbackServerStreamingHandler;
   template <class RequestType, class ResponseType>
-  friend class ::grpc::internal::CallbackBidiHandler;
+  friend class ::grpc_impl::internal::CallbackBidiHandler;
   template <::grpc::StatusCode code>
   friend class ::grpc::internal::ErrorMethodHandler;
   friend class ::grpc_impl::ClientContext;
@@ -317,7 +321,7 @@ class ServerContext {
 
   void BeginCompletionOp(::grpc::internal::Call* call,
                          std::function<void(bool)> callback,
-                         ::grpc::internal::ServerReactor* reactor);
+                         ::grpc_impl::internal::ServerReactor* reactor);
   /// Return the tag queued by BeginCompletionOp()
   ::grpc::internal::CompletionQueueTag* GetCompletionOpTag();
 

include/grpcpp/impl/codegen/service_type.h

@@ -149,8 +149,9 @@ class Service {
   void RequestAsyncUnary(int index, ::grpc_impl::ServerContext* context,
                          Message* request,
                          internal::ServerAsyncStreamingInterface* stream,
-                         CompletionQueue* call_cq,
-                         ServerCompletionQueue* notification_cq, void* tag) {
+                         ::grpc_impl::CompletionQueue* call_cq,
+                         ::grpc_impl::ServerCompletionQueue* notification_cq,
+                         void* tag) {
     // Typecast the index to size_t for indexing into a vector
     // while preserving the API that existed before a compiler
     // warning was first seen (grpc/grpc#11664)
@@ -160,8 +161,9 @@ class Service {
   }
   void RequestAsyncClientStreaming(
       int index, ::grpc_impl::ServerContext* context,
-      internal::ServerAsyncStreamingInterface* stream, CompletionQueue* call_cq,
-      ServerCompletionQueue* notification_cq, void* tag) {
+      internal::ServerAsyncStreamingInterface* stream,
+      ::grpc_impl::CompletionQueue* call_cq,
+      ::grpc_impl::ServerCompletionQueue* notification_cq, void* tag) {
     size_t idx = static_cast<size_t>(index);
     server_->RequestAsyncCall(methods_[idx].get(), context, stream, call_cq,
                               notification_cq, tag);
@@ -169,16 +171,18 @@ class Service {
   template <class Message>
   void RequestAsyncServerStreaming(
       int index, ::grpc_impl::ServerContext* context, Message* request,
-      internal::ServerAsyncStreamingInterface* stream, CompletionQueue* call_cq,
-      ServerCompletionQueue* notification_cq, void* tag) {
+      internal::ServerAsyncStreamingInterface* stream,
+      ::grpc_impl::CompletionQueue* call_cq,
+      ::grpc_impl::ServerCompletionQueue* notification_cq, void* tag) {
     size_t idx = static_cast<size_t>(index);
     server_->RequestAsyncCall(methods_[idx].get(), context, stream, call_cq,
                               notification_cq, tag, request);
   }
   void RequestAsyncBidiStreaming(
       int index, ::grpc_impl::ServerContext* context,
-      internal::ServerAsyncStreamingInterface* stream, CompletionQueue* call_cq,
-      ServerCompletionQueue* notification_cq, void* tag) {
+      internal::ServerAsyncStreamingInterface* stream,
+      ::grpc_impl::CompletionQueue* call_cq,
+      ::grpc_impl::ServerCompletionQueue* notification_cq, void* tag) {
     size_t idx = static_cast<size_t>(index);
     server_->RequestAsyncCall(methods_[idx].get(), context, stream, call_cq,
                               notification_cq, tag);

include/grpcpp/impl/codegen/sync_stream.h

@@ -19,918 +19,81 @@
 #ifndef GRPCPP_IMPL_CODEGEN_SYNC_STREAM_H
 #define GRPCPP_IMPL_CODEGEN_SYNC_STREAM_H
 
-#include <grpcpp/impl/codegen/call.h>
-#include <grpcpp/impl/codegen/channel_interface.h>
-#include <grpcpp/impl/codegen/client_context_impl.h>
-#include <grpcpp/impl/codegen/completion_queue.h>
-#include <grpcpp/impl/codegen/core_codegen_interface.h>
-#include <grpcpp/impl/codegen/server_context_impl.h>
-#include <grpcpp/impl/codegen/service_type.h>
-#include <grpcpp/impl/codegen/status.h>
+#include <grpcpp/impl/codegen/sync_stream_impl.h>
 
 namespace grpc {
 
 namespace internal {
-/// Common interface for all synchronous client side streaming.
-class ClientStreamingInterface {
- public:
-  virtual ~ClientStreamingInterface() {}
 
-  /// Block waiting until the stream finishes and a final status of the call is
-  /// available.
-  ///
-  /// It is appropriate to call this method when both:
-  ///   * the calling code (client-side) has no more message to send
-  ///     (this can be declared implicitly by calling this method, or
-  ///     explicitly through an earlier call to <i>WritesDone</i> method of the
-  ///     class in use, e.g. \a ClientWriterInterface::WritesDone or
-  ///     \a ClientReaderWriterInterface::WritesDone).
-  ///   * there are no more messages to be received from the server (which can
-  ///     be known implicitly, or explicitly from an earlier call to \a
-  ///     ReaderInterface::Read that returned "false").
-  ///
-  /// This function will return either:
-  /// - when all incoming messages have been read and the server has
-  ///   returned status.
-  /// - when the server has returned a non-OK status.
-  /// - OR when the call failed for some reason and the library generated a
-  ///   status.
-  ///
-  /// Return values:
-  ///   - \a Status contains the status code, message and details for the call
-  ///   - the \a ClientContext associated with this call is updated with
-  ///     possible trailing metadata sent from the server.
-  virtual Status Finish() = 0;
-};
+typedef ::grpc_impl::internal::ClientStreamingInterface
+    ClientStreamingInterface;
 
-/// Common interface for all synchronous server side streaming.
-class ServerStreamingInterface {
- public:
-  virtual ~ServerStreamingInterface() {}
+typedef ::grpc_impl::internal::ServerStreamingInterface
+    ServerStreamingInterface;
 
-  /// Block to send initial metadata to client.
-  /// This call is optional, but if it is used, it cannot be used concurrently
-  /// with or after the \a Finish method.
-  ///
-  /// The initial metadata that will be sent to the client will be
-  /// taken from the \a ServerContext associated with the call.
-  virtual void SendInitialMetadata() = 0;
-};
-
-/// An interface that yields a sequence of messages of type \a R.
 template <class R>
-class ReaderInterface {
- public:
-  virtual ~ReaderInterface() {}
-
-  /// Get an upper bound on the next message size available for reading on this
-  /// stream.
-  virtual bool NextMessageSize(uint32_t* sz) = 0;
-
-  /// Block to read a message and parse to \a msg. Returns \a true on success.
-  /// This is thread-safe with respect to \a Write or \WritesDone methods on
-  /// the same stream. It should not be called concurrently with another \a
-  /// Read on the same stream as the order of delivery will not be defined.
-  ///
-  /// \param[out] msg The read message.
-  ///
-  /// \return \a false when there will be no more incoming messages, either
-  /// because the other side has called \a WritesDone() or the stream has failed
-  /// (or been cancelled).
-  virtual bool Read(R* msg) = 0;
-};
+using ReaderInterface = ::grpc_impl::internal::ReaderInterface<R>;
 
-/// An interface that can be fed a sequence of messages of type \a W.
 template <class W>
-class WriterInterface {
- public:
-  virtual ~WriterInterface() {}
+using WriterInterface = ::grpc_impl::internal::WriterInterface<W>;
 
-  /// Block to write \a msg to the stream with WriteOptions \a options.
-  /// This is thread-safe with respect to \a ReaderInterface::Read
-  ///
-  /// \param msg The message to be written to the stream.
-  /// \param options The WriteOptions affecting the write operation.
-  ///
-  /// \return \a true on success, \a false when the stream has been closed.
-  virtual bool Write(const W& msg, WriteOptions options) = 0;
+template <class R>
+using ClientReaderFactory = ::grpc_impl::internal::ClientReaderFactory<R>;
 
-  /// Block to write \a msg to the stream with default write options.
-  /// This is thread-safe with respect to \a ReaderInterface::Read
-  ///
-  /// \param msg The message to be written to the stream.
-  ///
-  /// \return \a true on success, \a false when the stream has been closed.
-  inline bool Write(const W& msg) { return Write(msg, WriteOptions()); }
+template <class W>
+using ClientWriterFactory = ::grpc_impl::internal::ClientWriterFactory<W>;
 
-  /// Write \a msg and coalesce it with the writing of trailing metadata, using
-  /// WriteOptions \a options.
-  ///
-  /// For client, WriteLast is equivalent of performing Write and WritesDone in
-  /// a single step. \a msg and trailing metadata are coalesced and sent on wire
-  /// by calling this function. For server, WriteLast buffers the \a msg.
-  /// The writing of \a msg is held until the service handler returns,
-  /// where \a msg and trailing metadata are coalesced and sent on wire.
-  /// Note that WriteLast can only buffer \a msg up to the flow control window
-  /// size. If \a msg size is larger than the window size, it will be sent on
-  /// wire without buffering.
-  ///
-  /// \param[in] msg The message to be written to the stream.
-  /// \param[in] options The WriteOptions to be used to write this message.
-  void WriteLast(const W& msg, WriteOptions options) {
-    Write(msg, options.set_last_message());
-  }
-};
+template <class W, class R>
+using ClientReaderWriterFactory =
+    ::grpc_impl::internal::ClientReaderWriterFactory<W, R>;
 
 }  // namespace internal
 
-/// Client-side interface for streaming reads of message of type \a R.
 template <class R>
-class ClientReaderInterface : public internal::ClientStreamingInterface,
-                              public internal::ReaderInterface<R> {
- public:
-  /// Block to wait for initial metadata from server. The received metadata
-  /// can only be accessed after this call returns. Should only be called before
-  /// the first read. Calling this method is optional, and if it is not called
-  /// the metadata will be available in ClientContext after the first read.
-  virtual void WaitForInitialMetadata() = 0;
-};
+using ClientReaderInterface = ::grpc_impl::ClientReaderInterface<R>;
 
-namespace internal {
 template <class R>
-class ClientReaderFactory {
- public:
-  template <class W>
-  static ClientReader<R>* Create(ChannelInterface* channel,
-                                 const ::grpc::internal::RpcMethod& method,
-                                 ::grpc_impl::ClientContext* context,
-                                 const W& request) {
-    return new ClientReader<R>(channel, method, context, request);
-  }
-};
-}  // namespace internal
-
-/// Synchronous (blocking) client-side API for doing server-streaming RPCs,
-/// where the stream of messages coming from the server has messages
-/// of type \a R.
-template <class R>
-class ClientReader final : public ClientReaderInterface<R> {
- public:
-  /// See the \a ClientStreamingInterface.WaitForInitialMetadata method for
-  /// semantics.
-  ///
-  //  Side effect:
-  ///   Once complete, the initial metadata read from
-  ///   the server will be accessible through the \a ClientContext used to
-  ///   construct this object.
-  void WaitForInitialMetadata() override {
-    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
-
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
-        ops;
-    ops.RecvInitialMetadata(context_);
-    call_.PerformOps(&ops);
-    cq_.Pluck(&ops);  /// status ignored
-  }
+using ClientReader = ::grpc_impl::ClientReader<R>;
 
-  bool NextMessageSize(uint32_t* sz) override {
-    *sz = call_.max_receive_message_size();
-    return true;
-  }
-
-  /// See the \a ReaderInterface.Read method for semantics.
-  /// Side effect:
-  ///   This also receives initial metadata from the server, if not
-  ///   already received (if initial metadata is received, it can be then
-  ///   accessed through the \a ClientContext associated with this call).
-  bool Read(R* msg) override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                                ::grpc::internal::CallOpRecvMessage<R>>
-        ops;
-    if (!context_->initial_metadata_received_) {
-      ops.RecvInitialMetadata(context_);
-    }
-    ops.RecvMessage(msg);
-    call_.PerformOps(&ops);
-    return cq_.Pluck(&ops) && ops.got_message;
-  }
-
-  /// See the \a ClientStreamingInterface.Finish method for semantics.
-  ///
-  /// Side effect:
-  ///   The \a ClientContext associated with this call is updated with
-  ///   possible metadata received from the server.
-  Status Finish() override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpClientRecvStatus> ops;
-    Status status;
-    ops.ClientRecvStatus(context_, &status);
-    call_.PerformOps(&ops);
-    GPR_CODEGEN_ASSERT(cq_.Pluck(&ops));
-    return status;
-  }
-
- private:
-  friend class internal::ClientReaderFactory<R>;
-  ::grpc_impl::ClientContext* context_;
-  ::grpc_impl::CompletionQueue cq_;
-  ::grpc::internal::Call call_;
-
-  /// Block to create a stream and write the initial metadata and \a request
-  /// out. Note that \a context will be used to fill in custom initial
-  /// metadata used to send to the server when starting the call.
-  template <class W>
-  ClientReader(::grpc::ChannelInterface* channel,
-               const ::grpc::internal::RpcMethod& method,
-               ::grpc_impl::ClientContext* context, const W& request)
-      : context_(context),
-        cq_(grpc_completion_queue_attributes{
-            GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
-            nullptr}),  // Pluckable cq
-        call_(channel->CreateCall(method, context, &cq_)) {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                                ::grpc::internal::CallOpSendMessage,
-                                ::grpc::internal::CallOpClientSendClose>
-        ops;
-    ops.SendInitialMetadata(&context->send_initial_metadata_,
-                            context->initial_metadata_flags());
-    // TODO(ctiller): don't assert
-    GPR_CODEGEN_ASSERT(ops.SendMessagePtr(&request).ok());
-    ops.ClientSendClose();
-    call_.PerformOps(&ops);
-    cq_.Pluck(&ops);
-  }
-};
-
-/// Client-side interface for streaming writes of message type \a W.
 template <class W>
-class ClientWriterInterface : public internal::ClientStreamingInterface,
-                              public internal::WriterInterface<W> {
- public:
-  /// Half close writing from the client. (signal that the stream of messages
-  /// coming from the client is complete).
-  /// Blocks until currently-pending writes are completed.
-  /// Thread safe with respect to \a ReaderInterface::Read operations only
-  ///
-  /// \return Whether the writes were successful.
-  virtual bool WritesDone() = 0;
-};
+using ClientWriterInterface = ::grpc_impl::ClientWriterInterface<W>;
 
-namespace internal {
 template <class W>
-class ClientWriterFactory {
- public:
-  template <class R>
-  static ClientWriter<W>* Create(::grpc::ChannelInterface* channel,
-                                 const ::grpc::internal::RpcMethod& method,
-                                 ::grpc_impl::ClientContext* context,
-                                 R* response) {
-    return new ClientWriter<W>(channel, method, context, response);
-  }
-};
-}  // namespace internal
-
-/// Synchronous (blocking) client-side API for doing client-streaming RPCs,
-/// where the outgoing message stream coming from the client has messages of
-/// type \a W.
-template <class W>
-class ClientWriter : public ClientWriterInterface<W> {
- public:
-  /// See the \a ClientStreamingInterface.WaitForInitialMetadata method for
-  /// semantics.
-  ///
-  //  Side effect:
-  ///   Once complete, the initial metadata read from the server will be
-  ///   accessible through the \a ClientContext used to construct this object.
-  void WaitForInitialMetadata() {
-    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
-
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
-        ops;
-    ops.RecvInitialMetadata(context_);
-    call_.PerformOps(&ops);
-    cq_.Pluck(&ops);  // status ignored
-  }
+using ClientWriter = ::grpc_impl::ClientWriter<W>;
 
-  /// See the WriterInterface.Write(const W& msg, WriteOptions options) method
-  /// for semantics.
-  ///
-  /// Side effect:
-  ///   Also sends initial metadata if not already sent (using the
-  ///   \a ClientContext associated with this call).
-  using ::grpc::internal::WriterInterface<W>::Write;
-  bool Write(const W& msg, WriteOptions options) override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                                ::grpc::internal::CallOpSendMessage,
-                                ::grpc::internal::CallOpClientSendClose>
-        ops;
-
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-      ops.ClientSendClose();
-    }
-    if (context_->initial_metadata_corked_) {
-      ops.SendInitialMetadata(&context_->send_initial_metadata_,
-                              context_->initial_metadata_flags());
-      context_->set_initial_metadata_corked(false);
-    }
-    if (!ops.SendMessagePtr(&msg, options).ok()) {
-      return false;
-    }
-
-    call_.PerformOps(&ops);
-    return cq_.Pluck(&ops);
-  }
-
-  bool WritesDone() override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpClientSendClose> ops;
-    ops.ClientSendClose();
-    call_.PerformOps(&ops);
-    return cq_.Pluck(&ops);
-  }
-
-  /// See the ClientStreamingInterface.Finish method for semantics.
-  /// Side effects:
-  ///   - Also receives initial metadata if not already received.
-  ///   - Attempts to fill in the \a response parameter passed
-  ///     to the constructor of this instance with the response
-  ///     message from the server.
-  Status Finish() override {
-    Status status;
-    if (!context_->initial_metadata_received_) {
-      finish_ops_.RecvInitialMetadata(context_);
-    }
-    finish_ops_.ClientRecvStatus(context_, &status);
-    call_.PerformOps(&finish_ops_);
-    GPR_CODEGEN_ASSERT(cq_.Pluck(&finish_ops_));
-    return status;
-  }
-
- private:
-  friend class internal::ClientWriterFactory<W>;
-
-  /// Block to create a stream (i.e. send request headers and other initial
-  /// metadata to the server). Note that \a context will be used to fill
-  /// in custom initial metadata. \a response will be filled in with the
-  /// single expected response message from the server upon a successful
-  /// call to the \a Finish method of this instance.
-  template <class R>
-  ClientWriter(ChannelInterface* channel,
-               const ::grpc::internal::RpcMethod& method,
-               ::grpc_impl::ClientContext* context, R* response)
-      : context_(context),
-        cq_(grpc_completion_queue_attributes{
-            GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
-            nullptr}),  // Pluckable cq
-        call_(channel->CreateCall(method, context, &cq_)) {
-    finish_ops_.RecvMessage(response);
-    finish_ops_.AllowNoMessage();
-
-    if (!context_->initial_metadata_corked_) {
-      ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
-          ops;
-      ops.SendInitialMetadata(&context->send_initial_metadata_,
-                              context->initial_metadata_flags());
-      call_.PerformOps(&ops);
-      cq_.Pluck(&ops);
-    }
-  }
-
-  ::grpc_impl::ClientContext* context_;
-  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                              ::grpc::internal::CallOpGenericRecvMessage,
-                              ::grpc::internal::CallOpClientRecvStatus>
-      finish_ops_;
-  ::grpc_impl::CompletionQueue cq_;
-  ::grpc::internal::Call call_;
-};
-
-/// Client-side interface for bi-directional streaming with
-/// client-to-server stream messages of type \a W and
-/// server-to-client stream messages of type \a R.
 template <class W, class R>
-class ClientReaderWriterInterface : public internal::ClientStreamingInterface,
-                                    public internal::WriterInterface<W>,
-                                    public internal::ReaderInterface<R> {
- public:
-  /// Block to wait for initial metadata from server. The received metadata
-  /// can only be accessed after this call returns. Should only be called before
-  /// the first read. Calling this method is optional, and if it is not called
-  /// the metadata will be available in ClientContext after the first read.
-  virtual void WaitForInitialMetadata() = 0;
+using ClientReaderWriterInterface =
+    ::grpc_impl::ClientReaderWriterInterface<W, R>;
 
-  /// Half close writing from the client. (signal that the stream of messages
-  /// coming from the clinet is complete).
-  /// Blocks until currently-pending writes are completed.
-  /// Thread-safe with respect to \a ReaderInterface::Read
-  ///
-  /// \return Whether the writes were successful.
-  virtual bool WritesDone() = 0;
-};
-
-namespace internal {
 template <class W, class R>
-class ClientReaderWriterFactory {
- public:
-  static ClientReaderWriter<W, R>* Create(
-      ::grpc::ChannelInterface* channel,
-      const ::grpc::internal::RpcMethod& method,
-      ::grpc_impl::ClientContext* context) {
-    return new ClientReaderWriter<W, R>(channel, method, context);
-  }
-};
-}  // namespace internal
-
-/// Synchronous (blocking) client-side API for bi-directional streaming RPCs,
-/// where the outgoing message stream coming from the client has messages of
-/// type \a W, and the incoming messages stream coming from the server has
-/// messages of type \a R.
-template <class W, class R>
-class ClientReaderWriter final : public ClientReaderWriterInterface<W, R> {
- public:
-  /// Block waiting to read initial metadata from the server.
-  /// This call is optional, but if it is used, it cannot be used concurrently
-  /// with or after the \a Finish method.
-  ///
-  /// Once complete, the initial metadata read from the server will be
-  /// accessible through the \a ClientContext used to construct this object.
-  void WaitForInitialMetadata() override {
-    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
-
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
-        ops;
-    ops.RecvInitialMetadata(context_);
-    call_.PerformOps(&ops);
-    cq_.Pluck(&ops);  // status ignored
-  }
-
-  bool NextMessageSize(uint32_t* sz) override {
-    *sz = call_.max_receive_message_size();
-    return true;
-  }
-
-  /// See the \a ReaderInterface.Read method for semantics.
-  /// Side effect:
-  ///   Also receives initial metadata if not already received (updates the \a
-  ///   ClientContext associated with this call in that case).
-  bool Read(R* msg) override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                                ::grpc::internal::CallOpRecvMessage<R>>
-        ops;
-    if (!context_->initial_metadata_received_) {
-      ops.RecvInitialMetadata(context_);
-    }
-    ops.RecvMessage(msg);
-    call_.PerformOps(&ops);
-    return cq_.Pluck(&ops) && ops.got_message;
-  }
-
-  /// See the \a WriterInterface.Write method for semantics.
-  ///
-  /// Side effect:
-  ///   Also sends initial metadata if not already sent (using the
-  ///   \a ClientContext associated with this call to fill in values).
-  using ::grpc::internal::WriterInterface<W>::Write;
-  bool Write(const W& msg, WriteOptions options) override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
-                                ::grpc::internal::CallOpSendMessage,
-                                ::grpc::internal::CallOpClientSendClose>
-        ops;
-
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-      ops.ClientSendClose();
-    }
-    if (context_->initial_metadata_corked_) {
-      ops.SendInitialMetadata(&context_->send_initial_metadata_,
-                              context_->initial_metadata_flags());
-      context_->set_initial_metadata_corked(false);
-    }
-    if (!ops.SendMessagePtr(&msg, options).ok()) {
-      return false;
-    }
-
-    call_.PerformOps(&ops);
-    return cq_.Pluck(&ops);
-  }
-
-  bool WritesDone() override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpClientSendClose> ops;
-    ops.ClientSendClose();
-    call_.PerformOps(&ops);
-    return cq_.Pluck(&ops);
-  }
+using ClientReaderWriter = ::grpc_impl::ClientReaderWriter<W, R>;
 
-  /// See the ClientStreamingInterface.Finish method for semantics.
-  ///
-  /// Side effect:
-  ///   - the \a ClientContext associated with this call is updated with
-  ///     possible trailing metadata sent from the server.
-  Status Finish() override {
-    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
-                                ::grpc::internal::CallOpClientRecvStatus>
-        ops;
-    if (!context_->initial_metadata_received_) {
-      ops.RecvInitialMetadata(context_);
-    }
-    Status status;
-    ops.ClientRecvStatus(context_, &status);
-    call_.PerformOps(&ops);
-    GPR_CODEGEN_ASSERT(cq_.Pluck(&ops));
-    return status;
-  }
-
- private:
-  friend class internal::ClientReaderWriterFactory<W, R>;
-
-  ::grpc_impl::ClientContext* context_;
-  ::grpc_impl::CompletionQueue cq_;
-  ::grpc::internal::Call call_;
-
-  /// Block to create a stream and write the initial metadata and \a request
-  /// out. Note that \a context will be used to fill in custom initial metadata
-  /// used to send to the server when starting the call.
-  ClientReaderWriter(::grpc::ChannelInterface* channel,
-                     const ::grpc::internal::RpcMethod& method,
-                     ::grpc_impl::ClientContext* context)
-      : context_(context),
-        cq_(grpc_completion_queue_attributes{
-            GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
-            nullptr}),  // Pluckable cq
-        call_(channel->CreateCall(method, context, &cq_)) {
-    if (!context_->initial_metadata_corked_) {
-      ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
-          ops;
-      ops.SendInitialMetadata(&context->send_initial_metadata_,
-                              context->initial_metadata_flags());
-      call_.PerformOps(&ops);
-      cq_.Pluck(&ops);
-    }
-  }
-};
-
-/// Server-side interface for streaming reads of message of type \a R.
 template <class R>
-class ServerReaderInterface : public internal::ServerStreamingInterface,
-                              public internal::ReaderInterface<R> {};
+using ServerReaderInterface = ::grpc_impl::ServerReaderInterface<R>;
 
-/// Synchronous (blocking) server-side API for doing client-streaming RPCs,
-/// where the incoming message stream coming from the client has messages of
-/// type \a R.
 template <class R>
-class ServerReader final : public ServerReaderInterface<R> {
- public:
-  /// See the \a ServerStreamingInterface.SendInitialMetadata method
-  /// for semantics. Note that initial metadata will be affected by the
-  /// \a ServerContext associated with this call.
-  void SendInitialMetadata() override {
-    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-    internal::CallOpSet<internal::CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(&ctx_->initial_metadata_,
-                            ctx_->initial_metadata_flags());
-    if (ctx_->compression_level_set()) {
-      ops.set_compression_level(ctx_->compression_level());
-    }
-    ctx_->sent_initial_metadata_ = true;
-    call_->PerformOps(&ops);
-    call_->cq()->Pluck(&ops);
-  }
-
-  bool NextMessageSize(uint32_t* sz) override {
-    *sz = call_->max_receive_message_size();
-    return true;
-  }
+using ServerReader = ::grpc_impl::ServerReader<R>;
 
-  bool Read(R* msg) override {
-    internal::CallOpSet<internal::CallOpRecvMessage<R>> ops;
-    ops.RecvMessage(msg);
-    call_->PerformOps(&ops);
-    return call_->cq()->Pluck(&ops) && ops.got_message;
-  }
-
- private:
-  internal::Call* const call_;
-  ::grpc_impl::ServerContext* const ctx_;
-
-  template <class ServiceType, class RequestType, class ResponseType>
-  friend class internal::ClientStreamingHandler;
-
-  ServerReader(internal::Call* call, ::grpc_impl::ServerContext* ctx)
-      : call_(call), ctx_(ctx) {}
-};
-
-/// Server-side interface for streaming writes of message of type \a W.
 template <class W>
-class ServerWriterInterface : public internal::ServerStreamingInterface,
-                              public internal::WriterInterface<W> {};
+using ServerWriterInterface = ::grpc_impl::ServerWriterInterface<W>;
 
-/// Synchronous (blocking) server-side API for doing for doing a
-/// server-streaming RPCs, where the outgoing message stream coming from the
-/// server has messages of type \a W.
 template <class W>
-class ServerWriter final : public ServerWriterInterface<W> {
- public:
-  /// See the \a ServerStreamingInterface.SendInitialMetadata method
-  /// for semantics.
-  /// Note that initial metadata will be affected by the
-  /// \a ServerContext associated with this call.
-  void SendInitialMetadata() override {
-    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-    internal::CallOpSet<internal::CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(&ctx_->initial_metadata_,
-                            ctx_->initial_metadata_flags());
-    if (ctx_->compression_level_set()) {
-      ops.set_compression_level(ctx_->compression_level());
-    }
-    ctx_->sent_initial_metadata_ = true;
-    call_->PerformOps(&ops);
-    call_->cq()->Pluck(&ops);
-  }
+using ServerWriter = ::grpc_impl::ServerWriter<W>;
 
-  /// See the \a WriterInterface.Write method for semantics.
-  ///
-  /// Side effect:
-  ///   Also sends initial metadata if not already sent (using the
-  ///   \a ClientContext associated with this call to fill in values).
-  using internal::WriterInterface<W>::Write;
-  bool Write(const W& msg, WriteOptions options) override {
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-    }
-
-    if (!ctx_->pending_ops_.SendMessagePtr(&msg, options).ok()) {
-      return false;
-    }
-    if (!ctx_->sent_initial_metadata_) {
-      ctx_->pending_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                             ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        ctx_->pending_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-    call_->PerformOps(&ctx_->pending_ops_);
-    // if this is the last message we defer the pluck until AFTER we start
-    // the trailing md op. This prevents hangs. See
-    // https://github.com/grpc/grpc/issues/11546
-    if (options.is_last_message()) {
-      ctx_->has_pending_ops_ = true;
-      return true;
-    }
-    ctx_->has_pending_ops_ = false;
-    return call_->cq()->Pluck(&ctx_->pending_ops_);
-  }
-
- private:
-  internal::Call* const call_;
-  ::grpc_impl::ServerContext* const ctx_;
-
-  template <class ServiceType, class RequestType, class ResponseType>
-  friend class internal::ServerStreamingHandler;
-
-  ServerWriter(internal::Call* call, ::grpc_impl::ServerContext* ctx)
-      : call_(call), ctx_(ctx) {}
-};
-
-/// Server-side interface for bi-directional streaming.
 template <class W, class R>
-class ServerReaderWriterInterface : public internal::ServerStreamingInterface,
-                                    public internal::WriterInterface<W>,
-                                    public internal::ReaderInterface<R> {};
-
-/// Actual implementation of bi-directional streaming
-namespace internal {
-template <class W, class R>
-class ServerReaderWriterBody final {
- public:
-  ServerReaderWriterBody(Call* call, ::grpc_impl::ServerContext* ctx)
-      : call_(call), ctx_(ctx) {}
-
-  void SendInitialMetadata() {
-    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-    CallOpSet<CallOpSendInitialMetadata> ops;
-    ops.SendInitialMetadata(&ctx_->initial_metadata_,
-                            ctx_->initial_metadata_flags());
-    if (ctx_->compression_level_set()) {
-      ops.set_compression_level(ctx_->compression_level());
-    }
-    ctx_->sent_initial_metadata_ = true;
-    call_->PerformOps(&ops);
-    call_->cq()->Pluck(&ops);
-  }
+using ServerReaderWriterInterface =
+    ::grpc_impl::ServerReaderWriterInterface<W, R>;
 
-  bool NextMessageSize(uint32_t* sz) {
-    *sz = call_->max_receive_message_size();
-    return true;
-  }
-
-  bool Read(R* msg) {
-    CallOpSet<CallOpRecvMessage<R>> ops;
-    ops.RecvMessage(msg);
-    call_->PerformOps(&ops);
-    return call_->cq()->Pluck(&ops) && ops.got_message;
-  }
-
-  bool Write(const W& msg, WriteOptions options) {
-    if (options.is_last_message()) {
-      options.set_buffer_hint();
-    }
-    if (!ctx_->pending_ops_.SendMessagePtr(&msg, options).ok()) {
-      return false;
-    }
-    if (!ctx_->sent_initial_metadata_) {
-      ctx_->pending_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
-                                             ctx_->initial_metadata_flags());
-      if (ctx_->compression_level_set()) {
-        ctx_->pending_ops_.set_compression_level(ctx_->compression_level());
-      }
-      ctx_->sent_initial_metadata_ = true;
-    }
-    call_->PerformOps(&ctx_->pending_ops_);
-    // if this is the last message we defer the pluck until AFTER we start
-    // the trailing md op. This prevents hangs. See
-    // https://github.com/grpc/grpc/issues/11546
-    if (options.is_last_message()) {
-      ctx_->has_pending_ops_ = true;
-      return true;
-    }
-    ctx_->has_pending_ops_ = false;
-    return call_->cq()->Pluck(&ctx_->pending_ops_);
-  }
-
- private:
-  Call* const call_;
-  ::grpc_impl::ServerContext* const ctx_;
-};
-
-}  // namespace internal
-
-/// Synchronous (blocking) server-side API for a bidirectional
-/// streaming call, where the incoming message stream coming from the client has
-/// messages of type \a R, and the outgoing message streaming coming from
-/// the server has messages of type \a W.
 template <class W, class R>
-class ServerReaderWriter final : public ServerReaderWriterInterface<W, R> {
- public:
-  /// See the \a ServerStreamingInterface.SendInitialMetadata method
-  /// for semantics. Note that initial metadata will be affected by the
-  /// \a ServerContext associated with this call.
-  void SendInitialMetadata() override { body_.SendInitialMetadata(); }
-
-  bool NextMessageSize(uint32_t* sz) override {
-    return body_.NextMessageSize(sz);
-  }
-
-  bool Read(R* msg) override { return body_.Read(msg); }
-
-  /// See the \a WriterInterface.Write(const W& msg, WriteOptions options)
-  /// method for semantics.
-  /// Side effect:
-  ///   Also sends initial metadata if not already sent (using the \a
-  ///   ServerContext associated with this call).
-  using internal::WriterInterface<W>::Write;
-  bool Write(const W& msg, WriteOptions options) override {
-    return body_.Write(msg, options);
-  }
-
- private:
-  internal::ServerReaderWriterBody<W, R> body_;
-
-  friend class internal::TemplatedBidiStreamingHandler<ServerReaderWriter<W, R>,
-                                                       false>;
-  ServerReaderWriter(internal::Call* call, ::grpc_impl::ServerContext* ctx)
-      : body_(call, ctx) {}
-};
+using ServerReaderWriter = ::grpc_impl::ServerReaderWriter<W, R>;
 
-/// A class to represent a flow-controlled unary call. This is something
-/// of a hybrid between conventional unary and streaming. This is invoked
-/// through a unary call on the client side, but the server responds to it
-/// as though it were a single-ping-pong streaming call. The server can use
-/// the \a NextMessageSize method to determine an upper-bound on the size of
-/// the message. A key difference relative to streaming: ServerUnaryStreamer
-/// must have exactly 1 Read and exactly 1 Write, in that order, to function
-/// correctly. Otherwise, the RPC is in error.
 template <class RequestType, class ResponseType>
-class ServerUnaryStreamer final
-    : public ServerReaderWriterInterface<ResponseType, RequestType> {
- public:
-  /// Block to send initial metadata to client.
-  /// Implicit input parameter:
-  ///    - the \a ServerContext associated with this call will be used for
-  ///      sending initial metadata.
-  void SendInitialMetadata() override { body_.SendInitialMetadata(); }
+using ServerUnaryStreamer =
+    ::grpc_impl::ServerUnaryStreamer<RequestType, ResponseType>;
 
-  /// Get an upper bound on the request message size from the client.
-  bool NextMessageSize(uint32_t* sz) override {
-    return body_.NextMessageSize(sz);
-  }
-
-  /// Read a message of type \a R into \a msg. Completion will be notified by \a
-  /// tag on the associated completion queue.
-  /// This is thread-safe with respect to \a Write or \a WritesDone methods. It
-  /// should not be called concurrently with other streaming APIs
-  /// on the same stream. It is not meaningful to call it concurrently
-  /// with another \a ReaderInterface::Read on the same stream since reads on
-  /// the same stream are delivered in order.
-  ///
-  /// \param[out] msg Where to eventually store the read message.
-  /// \param[in] tag The tag identifying the operation.
-  bool Read(RequestType* request) override {
-    if (read_done_) {
-      return false;
-    }
-    read_done_ = true;
-    return body_.Read(request);
-  }
-
-  /// Block to write \a msg to the stream with WriteOptions \a options.
-  /// This is thread-safe with respect to \a ReaderInterface::Read
-  ///
-  /// \param msg The message to be written to the stream.
-  /// \param options The WriteOptions affecting the write operation.
-  ///
-  /// \return \a true on success, \a false when the stream has been closed.
-  using internal::WriterInterface<ResponseType>::Write;
-  bool Write(const ResponseType& response, WriteOptions options) override {
-    if (write_done_ || !read_done_) {
-      return false;
-    }
-    write_done_ = true;
-    return body_.Write(response, options);
-  }
-
- private:
-  internal::ServerReaderWriterBody<ResponseType, RequestType> body_;
-  bool read_done_;
-  bool write_done_;
-
-  friend class internal::TemplatedBidiStreamingHandler<
-      ServerUnaryStreamer<RequestType, ResponseType>, true>;
-  ServerUnaryStreamer(internal::Call* call, ::grpc_impl::ServerContext* ctx)
-      : body_(call, ctx), read_done_(false), write_done_(false) {}
-};
-
-/// A class to represent a flow-controlled server-side streaming call.
-/// This is something of a hybrid between server-side and bidi streaming.
-/// This is invoked through a server-side streaming call on the client side,
-/// but the server responds to it as though it were a bidi streaming call that
-/// must first have exactly 1 Read and then any number of Writes.
 template <class RequestType, class ResponseType>
-class ServerSplitStreamer final
-    : public ServerReaderWriterInterface<ResponseType, RequestType> {
- public:
-  /// Block to send initial metadata to client.
-  /// Implicit input parameter:
-  ///    - the \a ServerContext associated with this call will be used for
-  ///      sending initial metadata.
-  void SendInitialMetadata() override { body_.SendInitialMetadata(); }
-
-  /// Get an upper bound on the request message size from the client.
-  bool NextMessageSize(uint32_t* sz) override {
-    return body_.NextMessageSize(sz);
-  }
-
-  /// Read a message of type \a R into \a msg. Completion will be notified by \a
-  /// tag on the associated completion queue.
-  /// This is thread-safe with respect to \a Write or \a WritesDone methods. It
-  /// should not be called concurrently with other streaming APIs
-  /// on the same stream. It is not meaningful to call it concurrently
-  /// with another \a ReaderInterface::Read on the same stream since reads on
-  /// the same stream are delivered in order.
-  ///
-  /// \param[out] msg Where to eventually store the read message.
-  /// \param[in] tag The tag identifying the operation.
-  bool Read(RequestType* request) override {
-    if (read_done_) {
-      return false;
-    }
-    read_done_ = true;
-    return body_.Read(request);
-  }
-
-  /// Block to write \a msg to the stream with WriteOptions \a options.
-  /// This is thread-safe with respect to \a ReaderInterface::Read
-  ///
-  /// \param msg The message to be written to the stream.
-  /// \param options The WriteOptions affecting the write operation.
-  ///
-  /// \return \a true on success, \a false when the stream has been closed.
-  using internal::WriterInterface<ResponseType>::Write;
-  bool Write(const ResponseType& response, WriteOptions options) override {
-    return read_done_ && body_.Write(response, options);
-  }
-
- private:
-  internal::ServerReaderWriterBody<ResponseType, RequestType> body_;
-  bool read_done_;
-
-  friend class internal::TemplatedBidiStreamingHandler<
-      ServerSplitStreamer<RequestType, ResponseType>, false>;
-  ServerSplitStreamer(internal::Call* call, ::grpc_impl::ServerContext* ctx)
-      : body_(call, ctx), read_done_(false) {}
-};
+using ServerSplitStreamer =
+    ::grpc_impl::ServerSplitStreamer<RequestType, ResponseType>;
 
 }  // namespace grpc
 

include/grpcpp/impl/codegen/sync_stream_impl.h

@@ -0,0 +1,944 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef GRPCPP_IMPL_CODEGEN_SYNC_STREAM_IMPL_H
+#define GRPCPP_IMPL_CODEGEN_SYNC_STREAM_IMPL_H
+
+#include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/channel_interface.h>
+#include <grpcpp/impl/codegen/client_context_impl.h>
+#include <grpcpp/impl/codegen/completion_queue_impl.h>
+#include <grpcpp/impl/codegen/core_codegen_interface.h>
+#include <grpcpp/impl/codegen/server_context_impl.h>
+#include <grpcpp/impl/codegen/service_type.h>
+#include <grpcpp/impl/codegen/status.h>
+
+namespace grpc_impl {
+
+namespace internal {
+/// Common interface for all synchronous client side streaming.
+class ClientStreamingInterface {
+ public:
+  virtual ~ClientStreamingInterface() {}
+
+  /// Block waiting until the stream finishes and a final status of the call is
+  /// available.
+  ///
+  /// It is appropriate to call this method when both:
+  ///   * the calling code (client-side) has no more message to send
+  ///     (this can be declared implicitly by calling this method, or
+  ///     explicitly through an earlier call to <i>WritesDone</i> method of the
+  ///     class in use, e.g. \a ClientWriterInterface::WritesDone or
+  ///     \a ClientReaderWriterInterface::WritesDone).
+  ///   * there are no more messages to be received from the server (which can
+  ///     be known implicitly, or explicitly from an earlier call to \a
+  ///     ReaderInterface::Read that returned "false").
+  ///
+  /// This function will return either:
+  /// - when all incoming messages have been read and the server has
+  ///   returned status.
+  /// - when the server has returned a non-OK status.
+  /// - OR when the call failed for some reason and the library generated a
+  ///   status.
+  ///
+  /// Return values:
+  ///   - \a Status contains the status code, message and details for the call
+  ///   - the \a ClientContext associated with this call is updated with
+  ///     possible trailing metadata sent from the server.
+  virtual ::grpc::Status Finish() = 0;
+};
+
+/// Common interface for all synchronous server side streaming.
+class ServerStreamingInterface {
+ public:
+  virtual ~ServerStreamingInterface() {}
+
+  /// Block to send initial metadata to client.
+  /// This call is optional, but if it is used, it cannot be used concurrently
+  /// with or after the \a Finish method.
+  ///
+  /// The initial metadata that will be sent to the client will be
+  /// taken from the \a ServerContext associated with the call.
+  virtual void SendInitialMetadata() = 0;
+};
+
+/// An interface that yields a sequence of messages of type \a R.
+template <class R>
+class ReaderInterface {
+ public:
+  virtual ~ReaderInterface() {}
+
+  /// Get an upper bound on the next message size available for reading on this
+  /// stream.
+  virtual bool NextMessageSize(uint32_t* sz) = 0;
+
+  /// Block to read a message and parse to \a msg. Returns \a true on success.
+  /// This is thread-safe with respect to \a Write or \WritesDone methods on
+  /// the same stream. It should not be called concurrently with another \a
+  /// Read on the same stream as the order of delivery will not be defined.
+  ///
+  /// \param[out] msg The read message.
+  ///
+  /// \return \a false when there will be no more incoming messages, either
+  /// because the other side has called \a WritesDone() or the stream has failed
+  /// (or been cancelled).
+  virtual bool Read(R* msg) = 0;
+};
+
+/// An interface that can be fed a sequence of messages of type \a W.
+template <class W>
+class WriterInterface {
+ public:
+  virtual ~WriterInterface() {}
+
+  /// Block to write \a msg to the stream with WriteOptions \a options.
+  /// This is thread-safe with respect to \a ReaderInterface::Read
+  ///
+  /// \param msg The message to be written to the stream.
+  /// \param options The WriteOptions affecting the write operation.
+  ///
+  /// \return \a true on success, \a false when the stream has been closed.
+  virtual bool Write(const W& msg, ::grpc::WriteOptions options) = 0;
+
+  /// Block to write \a msg to the stream with default write options.
+  /// This is thread-safe with respect to \a ReaderInterface::Read
+  ///
+  /// \param msg The message to be written to the stream.
+  ///
+  /// \return \a true on success, \a false when the stream has been closed.
+  inline bool Write(const W& msg) { return Write(msg, ::grpc::WriteOptions()); }
+
+  /// Write \a msg and coalesce it with the writing of trailing metadata, using
+  /// WriteOptions \a options.
+  ///
+  /// For client, WriteLast is equivalent of performing Write and WritesDone in
+  /// a single step. \a msg and trailing metadata are coalesced and sent on wire
+  /// by calling this function. For server, WriteLast buffers the \a msg.
+  /// The writing of \a msg is held until the service handler returns,
+  /// where \a msg and trailing metadata are coalesced and sent on wire.
+  /// Note that WriteLast can only buffer \a msg up to the flow control window
+  /// size. If \a msg size is larger than the window size, it will be sent on
+  /// wire without buffering.
+  ///
+  /// \param[in] msg The message to be written to the stream.
+  /// \param[in] options The WriteOptions to be used to write this message.
+  void WriteLast(const W& msg, ::grpc::WriteOptions options) {
+    Write(msg, options.set_last_message());
+  }
+};
+
+}  // namespace internal
+
+/// Client-side interface for streaming reads of message of type \a R.
+template <class R>
+class ClientReaderInterface : public internal::ClientStreamingInterface,
+                              public internal::ReaderInterface<R> {
+ public:
+  /// Block to wait for initial metadata from server. The received metadata
+  /// can only be accessed after this call returns. Should only be called before
+  /// the first read. Calling this method is optional, and if it is not called
+  /// the metadata will be available in ClientContext after the first read.
+  virtual void WaitForInitialMetadata() = 0;
+};
+
+namespace internal {
+template <class R>
+class ClientReaderFactory {
+ public:
+  template <class W>
+  static ClientReader<R>* Create(::grpc::ChannelInterface* channel,
+                                 const ::grpc::internal::RpcMethod& method,
+                                 ::grpc_impl::ClientContext* context,
+                                 const W& request) {
+    return new ClientReader<R>(channel, method, context, request);
+  }
+};
+}  // namespace internal
+
+/// Synchronous (blocking) client-side API for doing server-streaming RPCs,
+/// where the stream of messages coming from the server has messages
+/// of type \a R.
+template <class R>
+class ClientReader final : public ClientReaderInterface<R> {
+ public:
+  /// See the \a ClientStreamingInterface.WaitForInitialMetadata method for
+  /// semantics.
+  ///
+  //  Side effect:
+  ///   Once complete, the initial metadata read from
+  ///   the server will be accessible through the \a ClientContext used to
+  ///   construct this object.
+  void WaitForInitialMetadata() override {
+    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
+
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
+        ops;
+    ops.RecvInitialMetadata(context_);
+    call_.PerformOps(&ops);
+    cq_.Pluck(&ops);  /// status ignored
+  }
+
+  bool NextMessageSize(uint32_t* sz) override {
+    *sz = call_.max_receive_message_size();
+    return true;
+  }
+
+  /// See the \a ReaderInterface.Read method for semantics.
+  /// Side effect:
+  ///   This also receives initial metadata from the server, if not
+  ///   already received (if initial metadata is received, it can be then
+  ///   accessed through the \a ClientContext associated with this call).
+  bool Read(R* msg) override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                                ::grpc::internal::CallOpRecvMessage<R>>
+        ops;
+    if (!context_->initial_metadata_received_) {
+      ops.RecvInitialMetadata(context_);
+    }
+    ops.RecvMessage(msg);
+    call_.PerformOps(&ops);
+    return cq_.Pluck(&ops) && ops.got_message;
+  }
+
+  /// See the \a ClientStreamingInterface.Finish method for semantics.
+  ///
+  /// Side effect:
+  ///   The \a ClientContext associated with this call is updated with
+  ///   possible metadata received from the server.
+  ::grpc::Status Finish() override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpClientRecvStatus> ops;
+    ::grpc::Status status;
+    ops.ClientRecvStatus(context_, &status);
+    call_.PerformOps(&ops);
+    GPR_CODEGEN_ASSERT(cq_.Pluck(&ops));
+    return status;
+  }
+
+ private:
+  friend class internal::ClientReaderFactory<R>;
+  ::grpc_impl::ClientContext* context_;
+  ::grpc_impl::CompletionQueue cq_;
+  ::grpc::internal::Call call_;
+
+  /// Block to create a stream and write the initial metadata and \a request
+  /// out. Note that \a context will be used to fill in custom initial
+  /// metadata used to send to the server when starting the call.
+  template <class W>
+  ClientReader(::grpc::ChannelInterface* channel,
+               const ::grpc::internal::RpcMethod& method,
+               ::grpc_impl::ClientContext* context, const W& request)
+      : context_(context),
+        cq_(grpc_completion_queue_attributes{
+            GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
+            nullptr}),  // Pluckable cq
+        call_(channel->CreateCall(method, context, &cq_)) {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                                ::grpc::internal::CallOpSendMessage,
+                                ::grpc::internal::CallOpClientSendClose>
+        ops;
+    ops.SendInitialMetadata(&context->send_initial_metadata_,
+                            context->initial_metadata_flags());
+    // TODO(ctiller): don't assert
+    GPR_CODEGEN_ASSERT(ops.SendMessagePtr(&request).ok());
+    ops.ClientSendClose();
+    call_.PerformOps(&ops);
+    cq_.Pluck(&ops);
+  }
+};
+
+/// Client-side interface for streaming writes of message type \a W.
+template <class W>
+class ClientWriterInterface : public internal::ClientStreamingInterface,
+                              public internal::WriterInterface<W> {
+ public:
+  /// Half close writing from the client. (signal that the stream of messages
+  /// coming from the client is complete).
+  /// Blocks until currently-pending writes are completed.
+  /// Thread safe with respect to \a ReaderInterface::Read operations only
+  ///
+  /// \return Whether the writes were successful.
+  virtual bool WritesDone() = 0;
+};
+
+namespace internal {
+template <class W>
+class ClientWriterFactory {
+ public:
+  template <class R>
+  static ClientWriter<W>* Create(::grpc::ChannelInterface* channel,
+                                 const ::grpc::internal::RpcMethod& method,
+                                 ::grpc_impl::ClientContext* context,
+                                 R* response) {
+    return new ClientWriter<W>(channel, method, context, response);
+  }
+};
+}  // namespace internal
+
+/// Synchronous (blocking) client-side API for doing client-streaming RPCs,
+/// where the outgoing message stream coming from the client has messages of
+/// type \a W.
+template <class W>
+class ClientWriter : public ClientWriterInterface<W> {
+ public:
+  /// See the \a ClientStreamingInterface.WaitForInitialMetadata method for
+  /// semantics.
+  ///
+  //  Side effect:
+  ///   Once complete, the initial metadata read from the server will be
+  ///   accessible through the \a ClientContext used to construct this object.
+  void WaitForInitialMetadata() {
+    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
+
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
+        ops;
+    ops.RecvInitialMetadata(context_);
+    call_.PerformOps(&ops);
+    cq_.Pluck(&ops);  // status ignored
+  }
+
+  /// See the WriterInterface.Write(const W& msg, WriteOptions options) method
+  /// for semantics.
+  ///
+  /// Side effect:
+  ///   Also sends initial metadata if not already sent (using the
+  ///   \a ClientContext associated with this call).
+  using internal::WriterInterface<W>::Write;
+  bool Write(const W& msg, ::grpc::WriteOptions options) override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                                ::grpc::internal::CallOpSendMessage,
+                                ::grpc::internal::CallOpClientSendClose>
+        ops;
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      ops.ClientSendClose();
+    }
+    if (context_->initial_metadata_corked_) {
+      ops.SendInitialMetadata(&context_->send_initial_metadata_,
+                              context_->initial_metadata_flags());
+      context_->set_initial_metadata_corked(false);
+    }
+    if (!ops.SendMessagePtr(&msg, options).ok()) {
+      return false;
+    }
+
+    call_.PerformOps(&ops);
+    return cq_.Pluck(&ops);
+  }
+
+  bool WritesDone() override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpClientSendClose> ops;
+    ops.ClientSendClose();
+    call_.PerformOps(&ops);
+    return cq_.Pluck(&ops);
+  }
+
+  /// See the ClientStreamingInterface.Finish method for semantics.
+  /// Side effects:
+  ///   - Also receives initial metadata if not already received.
+  ///   - Attempts to fill in the \a response parameter passed
+  ///     to the constructor of this instance with the response
+  ///     message from the server.
+  ::grpc::Status Finish() override {
+    ::grpc::Status status;
+    if (!context_->initial_metadata_received_) {
+      finish_ops_.RecvInitialMetadata(context_);
+    }
+    finish_ops_.ClientRecvStatus(context_, &status);
+    call_.PerformOps(&finish_ops_);
+    GPR_CODEGEN_ASSERT(cq_.Pluck(&finish_ops_));
+    return status;
+  }
+
+ private:
+  friend class internal::ClientWriterFactory<W>;
+
+  /// Block to create a stream (i.e. send request headers and other initial
+  /// metadata to the server). Note that \a context will be used to fill
+  /// in custom initial metadata. \a response will be filled in with the
+  /// single expected response message from the server upon a successful
+  /// call to the \a Finish method of this instance.
+  template <class R>
+  ClientWriter(::grpc::ChannelInterface* channel,
+               const ::grpc::internal::RpcMethod& method,
+               ::grpc_impl::ClientContext* context, R* response)
+      : context_(context),
+        cq_(grpc_completion_queue_attributes{
+            GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
+            nullptr}),  // Pluckable cq
+        call_(channel->CreateCall(method, context, &cq_)) {
+    finish_ops_.RecvMessage(response);
+    finish_ops_.AllowNoMessage();
+
+    if (!context_->initial_metadata_corked_) {
+      ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+          ops;
+      ops.SendInitialMetadata(&context->send_initial_metadata_,
+                              context->initial_metadata_flags());
+      call_.PerformOps(&ops);
+      cq_.Pluck(&ops);
+    }
+  }
+
+  ::grpc_impl::ClientContext* context_;
+  ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                              ::grpc::internal::CallOpGenericRecvMessage,
+                              ::grpc::internal::CallOpClientRecvStatus>
+      finish_ops_;
+  ::grpc_impl::CompletionQueue cq_;
+  ::grpc::internal::Call call_;
+};
+
+/// Client-side interface for bi-directional streaming with
+/// client-to-server stream messages of type \a W and
+/// server-to-client stream messages of type \a R.
+template <class W, class R>
+class ClientReaderWriterInterface : public internal::ClientStreamingInterface,
+                                    public internal::WriterInterface<W>,
+                                    public internal::ReaderInterface<R> {
+ public:
+  /// Block to wait for initial metadata from server. The received metadata
+  /// can only be accessed after this call returns. Should only be called before
+  /// the first read. Calling this method is optional, and if it is not called
+  /// the metadata will be available in ClientContext after the first read.
+  virtual void WaitForInitialMetadata() = 0;
+
+  /// Half close writing from the client. (signal that the stream of messages
+  /// coming from the clinet is complete).
+  /// Blocks until currently-pending writes are completed.
+  /// Thread-safe with respect to \a ReaderInterface::Read
+  ///
+  /// \return Whether the writes were successful.
+  virtual bool WritesDone() = 0;
+};
+
+namespace internal {
+template <class W, class R>
+class ClientReaderWriterFactory {
+ public:
+  static ClientReaderWriter<W, R>* Create(
+      ::grpc::ChannelInterface* channel,
+      const ::grpc::internal::RpcMethod& method,
+      ::grpc_impl::ClientContext* context) {
+    return new ClientReaderWriter<W, R>(channel, method, context);
+  }
+};
+}  // namespace internal
+
+/// Synchronous (blocking) client-side API for bi-directional streaming RPCs,
+/// where the outgoing message stream coming from the client has messages of
+/// type \a W, and the incoming messages stream coming from the server has
+/// messages of type \a R.
+template <class W, class R>
+class ClientReaderWriter final : public ClientReaderWriterInterface<W, R> {
+ public:
+  /// Block waiting to read initial metadata from the server.
+  /// This call is optional, but if it is used, it cannot be used concurrently
+  /// with or after the \a Finish method.
+  ///
+  /// Once complete, the initial metadata read from the server will be
+  /// accessible through the \a ClientContext used to construct this object.
+  void WaitForInitialMetadata() override {
+    GPR_CODEGEN_ASSERT(!context_->initial_metadata_received_);
+
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata>
+        ops;
+    ops.RecvInitialMetadata(context_);
+    call_.PerformOps(&ops);
+    cq_.Pluck(&ops);  // status ignored
+  }
+
+  bool NextMessageSize(uint32_t* sz) override {
+    *sz = call_.max_receive_message_size();
+    return true;
+  }
+
+  /// See the \a ReaderInterface.Read method for semantics.
+  /// Side effect:
+  ///   Also receives initial metadata if not already received (updates the \a
+  ///   ClientContext associated with this call in that case).
+  bool Read(R* msg) override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                                ::grpc::internal::CallOpRecvMessage<R>>
+        ops;
+    if (!context_->initial_metadata_received_) {
+      ops.RecvInitialMetadata(context_);
+    }
+    ops.RecvMessage(msg);
+    call_.PerformOps(&ops);
+    return cq_.Pluck(&ops) && ops.got_message;
+  }
+
+  /// See the \a WriterInterface.Write method for semantics.
+  ///
+  /// Side effect:
+  ///   Also sends initial metadata if not already sent (using the
+  ///   \a ClientContext associated with this call to fill in values).
+  using internal::WriterInterface<W>::Write;
+  bool Write(const W& msg, ::grpc::WriteOptions options) override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata,
+                                ::grpc::internal::CallOpSendMessage,
+                                ::grpc::internal::CallOpClientSendClose>
+        ops;
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      ops.ClientSendClose();
+    }
+    if (context_->initial_metadata_corked_) {
+      ops.SendInitialMetadata(&context_->send_initial_metadata_,
+                              context_->initial_metadata_flags());
+      context_->set_initial_metadata_corked(false);
+    }
+    if (!ops.SendMessagePtr(&msg, options).ok()) {
+      return false;
+    }
+
+    call_.PerformOps(&ops);
+    return cq_.Pluck(&ops);
+  }
+
+  bool WritesDone() override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpClientSendClose> ops;
+    ops.ClientSendClose();
+    call_.PerformOps(&ops);
+    return cq_.Pluck(&ops);
+  }
+
+  /// See the ClientStreamingInterface.Finish method for semantics.
+  ///
+  /// Side effect:
+  ///   - the \a ClientContext associated with this call is updated with
+  ///     possible trailing metadata sent from the server.
+  ::grpc::Status Finish() override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvInitialMetadata,
+                                ::grpc::internal::CallOpClientRecvStatus>
+        ops;
+    if (!context_->initial_metadata_received_) {
+      ops.RecvInitialMetadata(context_);
+    }
+    ::grpc::Status status;
+    ops.ClientRecvStatus(context_, &status);
+    call_.PerformOps(&ops);
+    GPR_CODEGEN_ASSERT(cq_.Pluck(&ops));
+    return status;
+  }
+
+ private:
+  friend class internal::ClientReaderWriterFactory<W, R>;
+
+  ::grpc_impl::ClientContext* context_;
+  ::grpc_impl::CompletionQueue cq_;
+  ::grpc::internal::Call call_;
+
+  /// Block to create a stream and write the initial metadata and \a request
+  /// out. Note that \a context will be used to fill in custom initial metadata
+  /// used to send to the server when starting the call.
+  ClientReaderWriter(::grpc::ChannelInterface* channel,
+                     const ::grpc::internal::RpcMethod& method,
+                     ::grpc_impl::ClientContext* context)
+      : context_(context),
+        cq_(grpc_completion_queue_attributes{
+            GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
+            nullptr}),  // Pluckable cq
+        call_(channel->CreateCall(method, context, &cq_)) {
+    if (!context_->initial_metadata_corked_) {
+      ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+          ops;
+      ops.SendInitialMetadata(&context->send_initial_metadata_,
+                              context->initial_metadata_flags());
+      call_.PerformOps(&ops);
+      cq_.Pluck(&ops);
+    }
+  }
+};
+
+/// Server-side interface for streaming reads of message of type \a R.
+template <class R>
+class ServerReaderInterface : public internal::ServerStreamingInterface,
+                              public internal::ReaderInterface<R> {};
+
+/// Synchronous (blocking) server-side API for doing client-streaming RPCs,
+/// where the incoming message stream coming from the client has messages of
+/// type \a R.
+template <class R>
+class ServerReader final : public ServerReaderInterface<R> {
+ public:
+  /// See the \a ServerStreamingInterface.SendInitialMetadata method
+  /// for semantics. Note that initial metadata will be affected by the
+  /// \a ServerContext associated with this call.
+  void SendInitialMetadata() override {
+    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+        ops;
+    ops.SendInitialMetadata(&ctx_->initial_metadata_,
+                            ctx_->initial_metadata_flags());
+    if (ctx_->compression_level_set()) {
+      ops.set_compression_level(ctx_->compression_level());
+    }
+    ctx_->sent_initial_metadata_ = true;
+    call_->PerformOps(&ops);
+    call_->cq()->Pluck(&ops);
+  }
+
+  bool NextMessageSize(uint32_t* sz) override {
+    *sz = call_->max_receive_message_size();
+    return true;
+  }
+
+  bool Read(R* msg) override {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>> ops;
+    ops.RecvMessage(msg);
+    call_->PerformOps(&ops);
+    return call_->cq()->Pluck(&ops) && ops.got_message;
+  }
+
+ private:
+  ::grpc::internal::Call* const call_;
+  ServerContext* const ctx_;
+
+  template <class ServiceType, class RequestType, class ResponseType>
+  friend class ::grpc::internal::ClientStreamingHandler;
+
+  ServerReader(::grpc::internal::Call* call, ::grpc_impl::ServerContext* ctx)
+      : call_(call), ctx_(ctx) {}
+};
+
+/// Server-side interface for streaming writes of message of type \a W.
+template <class W>
+class ServerWriterInterface : public internal::ServerStreamingInterface,
+                              public internal::WriterInterface<W> {};
+
+/// Synchronous (blocking) server-side API for doing for doing a
+/// server-streaming RPCs, where the outgoing message stream coming from the
+/// server has messages of type \a W.
+template <class W>
+class ServerWriter final : public ServerWriterInterface<W> {
+ public:
+  /// See the \a ServerStreamingInterface.SendInitialMetadata method
+  /// for semantics.
+  /// Note that initial metadata will be affected by the
+  /// \a ServerContext associated with this call.
+  void SendInitialMetadata() override {
+    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpSendInitialMetadata>
+        ops;
+    ops.SendInitialMetadata(&ctx_->initial_metadata_,
+                            ctx_->initial_metadata_flags());
+    if (ctx_->compression_level_set()) {
+      ops.set_compression_level(ctx_->compression_level());
+    }
+    ctx_->sent_initial_metadata_ = true;
+    call_->PerformOps(&ops);
+    call_->cq()->Pluck(&ops);
+  }
+
+  /// See the \a WriterInterface.Write method for semantics.
+  ///
+  /// Side effect:
+  ///   Also sends initial metadata if not already sent (using the
+  ///   \a ClientContext associated with this call to fill in values).
+  using internal::WriterInterface<W>::Write;
+  bool Write(const W& msg, ::grpc::WriteOptions options) override {
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+    }
+
+    if (!ctx_->pending_ops_.SendMessagePtr(&msg, options).ok()) {
+      return false;
+    }
+    if (!ctx_->sent_initial_metadata_) {
+      ctx_->pending_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                             ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        ctx_->pending_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+    call_->PerformOps(&ctx_->pending_ops_);
+    // if this is the last message we defer the pluck until AFTER we start
+    // the trailing md op. This prevents hangs. See
+    // https://github.com/grpc/grpc/issues/11546
+    if (options.is_last_message()) {
+      ctx_->has_pending_ops_ = true;
+      return true;
+    }
+    ctx_->has_pending_ops_ = false;
+    return call_->cq()->Pluck(&ctx_->pending_ops_);
+  }
+
+ private:
+  ::grpc::internal::Call* const call_;
+  ::grpc_impl::ServerContext* const ctx_;
+
+  template <class ServiceType, class RequestType, class ResponseType>
+  friend class ::grpc::internal::ServerStreamingHandler;
+
+  ServerWriter(::grpc::internal::Call* call, ::grpc_impl::ServerContext* ctx)
+      : call_(call), ctx_(ctx) {}
+};
+
+/// Server-side interface for bi-directional streaming.
+template <class W, class R>
+class ServerReaderWriterInterface : public internal::ServerStreamingInterface,
+                                    public internal::WriterInterface<W>,
+                                    public internal::ReaderInterface<R> {};
+
+/// Actual implementation of bi-directional streaming
+namespace internal {
+template <class W, class R>
+class ServerReaderWriterBody final {
+ public:
+  ServerReaderWriterBody(grpc::internal::Call* call,
+                         ::grpc_impl::ServerContext* ctx)
+      : call_(call), ctx_(ctx) {}
+
+  void SendInitialMetadata() {
+    GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+
+    grpc::internal::CallOpSet<grpc::internal::CallOpSendInitialMetadata> ops;
+    ops.SendInitialMetadata(&ctx_->initial_metadata_,
+                            ctx_->initial_metadata_flags());
+    if (ctx_->compression_level_set()) {
+      ops.set_compression_level(ctx_->compression_level());
+    }
+    ctx_->sent_initial_metadata_ = true;
+    call_->PerformOps(&ops);
+    call_->cq()->Pluck(&ops);
+  }
+
+  bool NextMessageSize(uint32_t* sz) {
+    *sz = call_->max_receive_message_size();
+    return true;
+  }
+
+  bool Read(R* msg) {
+    ::grpc::internal::CallOpSet<::grpc::internal::CallOpRecvMessage<R>> ops;
+    ops.RecvMessage(msg);
+    call_->PerformOps(&ops);
+    return call_->cq()->Pluck(&ops) && ops.got_message;
+  }
+
+  bool Write(const W& msg, ::grpc::WriteOptions options) {
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+    }
+    if (!ctx_->pending_ops_.SendMessagePtr(&msg, options).ok()) {
+      return false;
+    }
+    if (!ctx_->sent_initial_metadata_) {
+      ctx_->pending_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                             ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        ctx_->pending_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+    }
+    call_->PerformOps(&ctx_->pending_ops_);
+    // if this is the last message we defer the pluck until AFTER we start
+    // the trailing md op. This prevents hangs. See
+    // https://github.com/grpc/grpc/issues/11546
+    if (options.is_last_message()) {
+      ctx_->has_pending_ops_ = true;
+      return true;
+    }
+    ctx_->has_pending_ops_ = false;
+    return call_->cq()->Pluck(&ctx_->pending_ops_);
+  }
+
+ private:
+  grpc::internal::Call* const call_;
+  ::grpc_impl::ServerContext* const ctx_;
+};
+
+}  // namespace internal
+
+/// Synchronous (blocking) server-side API for a bidirectional
+/// streaming call, where the incoming message stream coming from the client has
+/// messages of type \a R, and the outgoing message streaming coming from
+/// the server has messages of type \a W.
+template <class W, class R>
+class ServerReaderWriter final : public ServerReaderWriterInterface<W, R> {
+ public:
+  /// See the \a ServerStreamingInterface.SendInitialMetadata method
+  /// for semantics. Note that initial metadata will be affected by the
+  /// \a ServerContext associated with this call.
+  void SendInitialMetadata() override { body_.SendInitialMetadata(); }
+
+  bool NextMessageSize(uint32_t* sz) override {
+    return body_.NextMessageSize(sz);
+  }
+
+  bool Read(R* msg) override { return body_.Read(msg); }
+
+  /// See the \a WriterInterface.Write(const W& msg, WriteOptions options)
+  /// method for semantics.
+  /// Side effect:
+  ///   Also sends initial metadata if not already sent (using the \a
+  ///   ServerContext associated with this call).
+  using internal::WriterInterface<W>::Write;
+  bool Write(const W& msg, ::grpc::WriteOptions options) override {
+    return body_.Write(msg, options);
+  }
+
+ private:
+  internal::ServerReaderWriterBody<W, R> body_;
+
+  friend class ::grpc::internal::TemplatedBidiStreamingHandler<
+      ServerReaderWriter<W, R>, false>;
+  ServerReaderWriter(::grpc::internal::Call* call,
+                     ::grpc_impl::ServerContext* ctx)
+      : body_(call, ctx) {}
+};
+
+/// A class to represent a flow-controlled unary call. This is something
+/// of a hybrid between conventional unary and streaming. This is invoked
+/// through a unary call on the client side, but the server responds to it
+/// as though it were a single-ping-pong streaming call. The server can use
+/// the \a NextMessageSize method to determine an upper-bound on the size of
+/// the message. A key difference relative to streaming: ServerUnaryStreamer
+/// must have exactly 1 Read and exactly 1 Write, in that order, to function
+/// correctly. Otherwise, the RPC is in error.
+template <class RequestType, class ResponseType>
+class ServerUnaryStreamer final
+    : public ServerReaderWriterInterface<ResponseType, RequestType> {
+ public:
+  /// Block to send initial metadata to client.
+  /// Implicit input parameter:
+  ///    - the \a ServerContext associated with this call will be used for
+  ///      sending initial metadata.
+  void SendInitialMetadata() override { body_.SendInitialMetadata(); }
+
+  /// Get an upper bound on the request message size from the client.
+  bool NextMessageSize(uint32_t* sz) override {
+    return body_.NextMessageSize(sz);
+  }
+
+  /// Read a message of type \a R into \a msg. Completion will be notified by \a
+  /// tag on the associated completion queue.
+  /// This is thread-safe with respect to \a Write or \a WritesDone methods. It
+  /// should not be called concurrently with other streaming APIs
+  /// on the same stream. It is not meaningful to call it concurrently
+  /// with another \a ReaderInterface::Read on the same stream since reads on
+  /// the same stream are delivered in order.
+  ///
+  /// \param[out] msg Where to eventually store the read message.
+  /// \param[in] tag The tag identifying the operation.
+  bool Read(RequestType* request) override {
+    if (read_done_) {
+      return false;
+    }
+    read_done_ = true;
+    return body_.Read(request);
+  }
+
+  /// Block to write \a msg to the stream with WriteOptions \a options.
+  /// This is thread-safe with respect to \a ReaderInterface::Read
+  ///
+  /// \param msg The message to be written to the stream.
+  /// \param options The WriteOptions affecting the write operation.
+  ///
+  /// \return \a true on success, \a false when the stream has been closed.
+  using internal::WriterInterface<ResponseType>::Write;
+  bool Write(const ResponseType& response,
+             ::grpc::WriteOptions options) override {
+    if (write_done_ || !read_done_) {
+      return false;
+    }
+    write_done_ = true;
+    return body_.Write(response, options);
+  }
+
+ private:
+  internal::ServerReaderWriterBody<ResponseType, RequestType> body_;
+  bool read_done_;
+  bool write_done_;
+
+  friend class ::grpc::internal::TemplatedBidiStreamingHandler<
+      ServerUnaryStreamer<RequestType, ResponseType>, true>;
+  ServerUnaryStreamer(::grpc::internal::Call* call,
+                      ::grpc_impl::ServerContext* ctx)
+      : body_(call, ctx), read_done_(false), write_done_(false) {}
+};
+
+/// A class to represent a flow-controlled server-side streaming call.
+/// This is something of a hybrid between server-side and bidi streaming.
+/// This is invoked through a server-side streaming call on the client side,
+/// but the server responds to it as though it were a bidi streaming call that
+/// must first have exactly 1 Read and then any number of Writes.
+template <class RequestType, class ResponseType>
+class ServerSplitStreamer final
+    : public ServerReaderWriterInterface<ResponseType, RequestType> {
+ public:
+  /// Block to send initial metadata to client.
+  /// Implicit input parameter:
+  ///    - the \a ServerContext associated with this call will be used for
+  ///      sending initial metadata.
+  void SendInitialMetadata() override { body_.SendInitialMetadata(); }
+
+  /// Get an upper bound on the request message size from the client.
+  bool NextMessageSize(uint32_t* sz) override {
+    return body_.NextMessageSize(sz);
+  }
+
+  /// Read a message of type \a R into \a msg. Completion will be notified by \a
+  /// tag on the associated completion queue.
+  /// This is thread-safe with respect to \a Write or \a WritesDone methods. It
+  /// should not be called concurrently with other streaming APIs
+  /// on the same stream. It is not meaningful to call it concurrently
+  /// with another \a ReaderInterface::Read on the same stream since reads on
+  /// the same stream are delivered in order.
+  ///
+  /// \param[out] msg Where to eventually store the read message.
+  /// \param[in] tag The tag identifying the operation.
+  bool Read(RequestType* request) override {
+    if (read_done_) {
+      return false;
+    }
+    read_done_ = true;
+    return body_.Read(request);
+  }
+
+  /// Block to write \a msg to the stream with WriteOptions \a options.
+  /// This is thread-safe with respect to \a ReaderInterface::Read
+  ///
+  /// \param msg The message to be written to the stream.
+  /// \param options The WriteOptions affecting the write operation.
+  ///
+  /// \return \a true on success, \a false when the stream has been closed.
+  using internal::WriterInterface<ResponseType>::Write;
+  bool Write(const ResponseType& response,
+             ::grpc::WriteOptions options) override {
+    return read_done_ && body_.Write(response, options);
+  }
+
+ private:
+  internal::ServerReaderWriterBody<ResponseType, RequestType> body_;
+  bool read_done_;
+
+  friend class ::grpc::internal::TemplatedBidiStreamingHandler<
+      ServerSplitStreamer<RequestType, ResponseType>, false>;
+  ServerSplitStreamer(::grpc::internal::Call* call,
+                      ::grpc_impl::ServerContext* ctx)
+      : body_(call, ctx), read_done_(false) {}
+};
+
+}  // namespace grpc_impl
+
+#endif  // GRPCPP_IMPL_CODEGEN_SYNC_STREAM_IMPL_H

include/grpcpp/server_builder_impl.h

@@ -112,10 +112,6 @@ class ServerBuilder {
   ///
   /// It can be invoked multiple times.
   ///
-  /// If port is not provided in the \a addr (e.g., "1.2.3.4:" or "1.2.3.4"),
-  /// the default port (i.e., https) is used.  To request an ephemeral port,
-  /// \a addr must include 0 as the port number (e.g., "1.2.3.4:0").
-  ///
   /// \param addr_uri The address to try to bind to the server in URI form. If
   /// the scheme name is omitted, "dns:///" is assumed. To bind to any address,
   /// please use IPv6 any, i.e., [::]:<port>, which also accepts IPv4

include/grpcpp/support/async_stream_impl.h

@@ -0,0 +1,24 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_SUPPORT_ASYNC_STREAM_IMPL_H
+#define GRPCPP_SUPPORT_ASYNC_STREAM_IMPL_H
+
+#include <grpcpp/impl/codegen/async_stream_impl.h>
+
+#endif  // GRPCPP_SUPPORT_ASYNC_STREAM_IMPL_H

include/grpcpp/support/async_unary_call_impl.h

@@ -0,0 +1,24 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_SUPPORT_ASYNC_UNARY_CALL_IMPL_H
+#define GRPCPP_SUPPORT_ASYNC_UNARY_CALL_IMPL_H
+
+#include <grpcpp/impl/codegen/async_unary_call_impl.h>
+
+#endif  // GRPCPP_SUPPORT_ASYNC_UNARY_CALL_IMPL_H

include/grpcpp/support/client_callback_impl.h

@@ -0,0 +1,24 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_SUPPORT_CLIENT_CALLBACK_IMPL_H
+#define GRPCPP_SUPPORT_CLIENT_CALLBACK_IMPL_H
+
+#include <grpcpp/impl/codegen/client_callback_impl.h>
+
+#endif  // GRPCPP_SUPPORT_CLIENT_CALLBACK_IMPL_H

include/grpcpp/support/server_callback_impl.h

@@ -0,0 +1,24 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_SUPPORT_SERVER_CALLBACK_IMPL_H
+#define GRPCPP_SUPPORT_SERVER_CALLBACK_IMPL_H
+
+#include <grpcpp/impl/codegen/server_callback_impl.h>
+
+#endif  // GRPCPP_SUPPORT_SERVER_CALLBACK_IMPL_H

include/grpcpp/support/sync_stream_impl.h

@@ -0,0 +1,24 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPCPP_SUPPORT_SYNC_STREAM_IMPL_H
+#define GRPCPP_SUPPORT_SYNC_STREAM_IMPL_H
+
+#include <grpcpp/impl/codegen/sync_stream_impl.h>
+
+#endif  // GRPCPP_SUPPORT_SYNC_STREAM_IMPL_H

src/compiler/cpp_generator.cc

@@ -143,6 +143,7 @@ grpc::string GetHeaderIncludes(grpc_generator::File* file,
         "grpcpp/impl/codegen/async_unary_call.h",
         "grpcpp/impl/codegen/client_callback.h",
         "grpcpp/impl/codegen/client_context.h",
+        "grpcpp/impl/codegen/completion_queue.h",
         "grpcpp/impl/codegen/method_handler_impl.h",
         "grpcpp/impl/codegen/proto_utils.h",
         "grpcpp/impl/codegen/rpc_method.h",
@@ -946,11 +947,12 @@ void PrintHeaderServerCallbackMethodsHelper(
         "  abort();\n"
         "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
         "}\n");
-    printer->Print(*vars,
-                   "virtual ::grpc::experimental::ServerReadReactor< "
-                   "$RealRequest$, $RealResponse$>* $Method$() {\n"
-                   "  return new ::grpc::internal::UnimplementedReadReactor<\n"
-                   "    $RealRequest$, $RealResponse$>;}\n");
+    printer->Print(
+        *vars,
+        "virtual ::grpc::experimental::ServerReadReactor< "
+        "$RealRequest$, $RealResponse$>* $Method$() {\n"
+        "  return new ::grpc_impl::internal::UnimplementedReadReactor<\n"
+        "    $RealRequest$, $RealResponse$>;}\n");
   } else if (ServerOnlyStreaming(method)) {
     printer->Print(
         *vars,
@@ -962,11 +964,12 @@ void PrintHeaderServerCallbackMethodsHelper(
         "  abort();\n"
         "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
         "}\n");
-    printer->Print(*vars,
-                   "virtual ::grpc::experimental::ServerWriteReactor< "
-                   "$RealRequest$, $RealResponse$>* $Method$() {\n"
-                   "  return new ::grpc::internal::UnimplementedWriteReactor<\n"
-                   "    $RealRequest$, $RealResponse$>;}\n");
+    printer->Print(
+        *vars,
+        "virtual ::grpc::experimental::ServerWriteReactor< "
+        "$RealRequest$, $RealResponse$>* $Method$() {\n"
+        "  return new ::grpc_impl::internal::UnimplementedWriteReactor<\n"
+        "    $RealRequest$, $RealResponse$>;}\n");
   } else if (method->BidiStreaming()) {
     printer->Print(
         *vars,
@@ -978,11 +981,12 @@ void PrintHeaderServerCallbackMethodsHelper(
         "  abort();\n"
         "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
         "}\n");
-    printer->Print(*vars,
-                   "virtual ::grpc::experimental::ServerBidiReactor< "
-                   "$RealRequest$, $RealResponse$>* $Method$() {\n"
-                   "  return new ::grpc::internal::UnimplementedBidiReactor<\n"
-                   "    $RealRequest$, $RealResponse$>;}\n");
+    printer->Print(
+        *vars,
+        "virtual ::grpc::experimental::ServerBidiReactor< "
+        "$RealRequest$, $RealResponse$>* $Method$() {\n"
+        "  return new ::grpc_impl::internal::UnimplementedBidiReactor<\n"
+        "    $RealRequest$, $RealResponse$>;}\n");
   }
 }
 
@@ -1010,7 +1014,7 @@ void PrintHeaderServerMethodCallback(
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackUnaryHandler< "
+        "    new ::grpc_impl::internal::CallbackUnaryHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this](::grpc::ServerContext* context,\n"
         "             const $RealRequest$* request,\n"
@@ -1024,7 +1028,7 @@ void PrintHeaderServerMethodCallback(
                    "void SetMessageAllocatorFor_$Method$(\n"
                    "    ::grpc::experimental::MessageAllocator< "
                    "$RealRequest$, $RealResponse$>* allocator) {\n"
-                   "  static_cast<::grpc::internal::CallbackUnaryHandler< "
+                   "  static_cast<::grpc_impl::internal::CallbackUnaryHandler< "
                    "$RealRequest$, $RealResponse$>*>(\n"
                    "      ::grpc::Service::experimental().GetHandler($Idx$))\n"
                    "          ->SetMessageAllocator(allocator);\n");
@@ -1032,21 +1036,21 @@ void PrintHeaderServerMethodCallback(
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackClientStreamingHandler< "
+        "    new ::grpc_impl::internal::CallbackClientStreamingHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this] { return this->$Method$(); }));\n");
   } else if (ServerOnlyStreaming(method)) {
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackServerStreamingHandler< "
+        "    new ::grpc_impl::internal::CallbackServerStreamingHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this] { return this->$Method$(); }));\n");
   } else if (method->BidiStreaming()) {
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackBidiHandler< "
+        "    new ::grpc_impl::internal::CallbackBidiHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this] { return this->$Method$(); }));\n");
   }
@@ -1084,7 +1088,7 @@ void PrintHeaderServerMethodRawCallback(
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodRawCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackUnaryHandler< "
+        "    new ::grpc_impl::internal::CallbackUnaryHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this](::grpc::ServerContext* context,\n"
         "             const $RealRequest$* request,\n"
@@ -1098,21 +1102,21 @@ void PrintHeaderServerMethodRawCallback(
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodRawCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackClientStreamingHandler< "
+        "    new ::grpc_impl::internal::CallbackClientStreamingHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this] { return this->$Method$(); }));\n");
   } else if (ServerOnlyStreaming(method)) {
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodRawCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackServerStreamingHandler< "
+        "    new ::grpc_impl::internal::CallbackServerStreamingHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this] { return this->$Method$(); }));\n");
   } else if (method->BidiStreaming()) {
     printer->Print(
         *vars,
         "  ::grpc::Service::experimental().MarkMethodRawCallback($Idx$,\n"
-        "    new ::grpc::internal::CallbackBidiHandler< "
+        "    new ::grpc_impl::internal::CallbackBidiHandler< "
         "$RealRequest$, $RealResponse$>(\n"
         "      [this] { return this->$Method$(); }));\n");
   }
@@ -1705,7 +1709,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                    "const $Request$* request, $Response$* response, "
                    "std::function<void(::grpc::Status)> f) {\n");
     printer->Print(*vars,
-                   "  ::grpc::internal::CallbackUnaryCall"
+                   "  ::grpc_impl::internal::CallbackUnaryCall"
                    "(stub_->channel_.get(), stub_->rpcmethod_$Method$_, "
                    "context, request, response, std::move(f));\n}\n\n");
 
@@ -1715,7 +1719,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                    "const ::grpc::ByteBuffer* request, $Response$* response, "
                    "std::function<void(::grpc::Status)> f) {\n");
     printer->Print(*vars,
-                   "  ::grpc::internal::CallbackUnaryCall"
+                   "  ::grpc_impl::internal::CallbackUnaryCall"
                    "(stub_->channel_.get(), stub_->rpcmethod_$Method$_, "
                    "context, request, response, std::move(f));\n}\n\n");
 
@@ -1725,7 +1729,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                    "const $Request$* request, $Response$* response, "
                    "::grpc::experimental::ClientUnaryReactor* reactor) {\n");
     printer->Print(*vars,
-                   "  ::grpc::internal::ClientCallbackUnaryFactory::Create"
+                   "  ::grpc_impl::internal::ClientCallbackUnaryFactory::Create"
                    "(stub_->channel_.get(), stub_->rpcmethod_$Method$_, "
                    "context, request, response, reactor);\n}\n\n");
 
@@ -1735,7 +1739,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                    "const ::grpc::ByteBuffer* request, $Response$* response, "
                    "::grpc::experimental::ClientUnaryReactor* reactor) {\n");
     printer->Print(*vars,
-                   "  ::grpc::internal::ClientCallbackUnaryFactory::Create"
+                   "  ::grpc_impl::internal::ClientCallbackUnaryFactory::Create"
                    "(stub_->channel_.get(), stub_->rpcmethod_$Method$_, "
                    "context, request, response, reactor);\n}\n\n");
 
@@ -1751,7 +1755,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
       printer->Print(
           *vars,
           "  return "
-          "::grpc::internal::ClientAsyncResponseReaderFactory< $Response$>"
+          "::grpc_impl::internal::ClientAsyncResponseReaderFactory< $Response$>"
           "::Create(channel_.get(), cq, "
           "rpcmethod_$Method$_, "
           "context, request, $AsyncStart$);\n"
@@ -1762,13 +1766,13 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                    "::grpc::ClientWriter< $Request$>* "
                    "$ns$$Service$::Stub::$Method$Raw("
                    "::grpc::ClientContext* context, $Response$* response) {\n");
-    printer->Print(
-        *vars,
-        "  return ::grpc::internal::ClientWriterFactory< $Request$>::Create("
-        "channel_.get(), "
-        "rpcmethod_$Method$_, "
-        "context, response);\n"
-        "}\n\n");
+    printer->Print(*vars,
+                   "  return ::grpc_impl::internal::ClientWriterFactory< "
+                   "$Request$>::Create("
+                   "channel_.get(), "
+                   "rpcmethod_$Method$_, "
+                   "context, response);\n"
+                   "}\n\n");
 
     printer->Print(
         *vars,
@@ -1777,7 +1781,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
         "$Response$* response, "
         "::grpc::experimental::ClientWriteReactor< $Request$>* reactor) {\n");
     printer->Print(*vars,
-                   "  ::grpc::internal::ClientCallbackWriterFactory< "
+                   "  ::grpc_impl::internal::ClientCallbackWriterFactory< "
                    "$Request$>::Create("
                    "stub_->channel_.get(), "
                    "stub_->rpcmethod_$Method$_, "
@@ -1796,7 +1800,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                      "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
       printer->Print(
           *vars,
-          "  return ::grpc::internal::ClientAsyncWriterFactory< $Request$>"
+          "  return ::grpc_impl::internal::ClientAsyncWriterFactory< $Request$>"
           "::Create(channel_.get(), cq, "
           "rpcmethod_$Method$_, "
           "context, response, $AsyncStart$$AsyncCreateArgs$);\n"
@@ -1808,13 +1812,13 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
         "::grpc::ClientReader< $Response$>* "
         "$ns$$Service$::Stub::$Method$Raw("
         "::grpc::ClientContext* context, const $Request$& request) {\n");
-    printer->Print(
-        *vars,
-        "  return ::grpc::internal::ClientReaderFactory< $Response$>::Create("
-        "channel_.get(), "
-        "rpcmethod_$Method$_, "
-        "context, request);\n"
-        "}\n\n");
+    printer->Print(*vars,
+                   "  return ::grpc_impl::internal::ClientReaderFactory< "
+                   "$Response$>::Create("
+                   "channel_.get(), "
+                   "rpcmethod_$Method$_, "
+                   "context, request);\n"
+                   "}\n\n");
 
     printer->Print(
         *vars,
@@ -1823,7 +1827,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
         "$Request$* request, "
         "::grpc::experimental::ClientReadReactor< $Response$>* reactor) {\n");
     printer->Print(*vars,
-                   "  ::grpc::internal::ClientCallbackReaderFactory< "
+                   "  ::grpc_impl::internal::ClientCallbackReaderFactory< "
                    "$Response$>::Create("
                    "stub_->channel_.get(), "
                    "stub_->rpcmethod_$Method$_, "
@@ -1843,7 +1847,8 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
           "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
       printer->Print(
           *vars,
-          "  return ::grpc::internal::ClientAsyncReaderFactory< $Response$>"
+          "  return ::grpc_impl::internal::ClientAsyncReaderFactory< "
+          "$Response$>"
           "::Create(channel_.get(), cq, "
           "rpcmethod_$Method$_, "
           "context, request, $AsyncStart$$AsyncCreateArgs$);\n"
@@ -1855,7 +1860,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
         "::grpc::ClientReaderWriter< $Request$, $Response$>* "
         "$ns$$Service$::Stub::$Method$Raw(::grpc::ClientContext* context) {\n");
     printer->Print(*vars,
-                   "  return ::grpc::internal::ClientReaderWriterFactory< "
+                   "  return ::grpc_impl::internal::ClientReaderWriterFactory< "
                    "$Request$, $Response$>::Create("
                    "channel_.get(), "
                    "rpcmethod_$Method$_, "
@@ -1868,13 +1873,14 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
         "ClientContext* context, "
         "::grpc::experimental::ClientBidiReactor< $Request$,$Response$>* "
         "reactor) {\n");
-    printer->Print(*vars,
-                   "  ::grpc::internal::ClientCallbackReaderWriterFactory< "
-                   "$Request$,$Response$>::Create("
-                   "stub_->channel_.get(), "
-                   "stub_->rpcmethod_$Method$_, "
-                   "context, reactor);\n"
-                   "}\n\n");
+    printer->Print(
+        *vars,
+        "  ::grpc_impl::internal::ClientCallbackReaderWriterFactory< "
+        "$Request$,$Response$>::Create("
+        "stub_->channel_.get(), "
+        "stub_->rpcmethod_$Method$_, "
+        "context, reactor);\n"
+        "}\n\n");
 
     for (auto async_prefix : async_prefixes) {
       (*vars)["AsyncPrefix"] = async_prefix.prefix;
@@ -1888,7 +1894,7 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                      "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
       printer->Print(*vars,
                      "  return "
-                     "::grpc::internal::ClientAsyncReaderWriterFactory< "
+                     "::grpc_impl::internal::ClientAsyncReaderWriterFactory< "
                      "$Request$, $Response$>::Create("
                      "channel_.get(), cq, "
                      "rpcmethod_$Method$_, "
@@ -2279,7 +2285,8 @@ void PrintMockClientMethods(grpc_generator::Printer* printer,
       printer->Print(
           *vars,
           "MOCK_METHOD$MockArgs$($AsyncPrefix$$Method$Raw, "
-          "::grpc::ClientAsyncReaderWriterInterface<$Request$, $Response$>*"
+          "::grpc::ClientAsyncReaderWriterInterface<$Request$, "
+          "$Response$>*"
           "(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq"
           "$AsyncMethodParams$));\n");
     }

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

@@ -433,6 +433,8 @@ void AresDnsResolver::StartResolvingLocked() {
 
 class AresDnsResolverFactory : public ResolverFactory {
  public:
+  bool IsValidUri(const grpc_uri* uri) const override { return true; }
+
   OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
     return OrphanablePtr<Resolver>(New<AresDnsResolver>(std::move(args)));
   }

src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.cc

@@ -258,11 +258,16 @@ void NativeDnsResolver::StartResolvingLocked() {
 
 class NativeDnsResolverFactory : public ResolverFactory {
  public:
-  OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
-    if (GPR_UNLIKELY(0 != strcmp(args.uri->authority, ""))) {
+  bool IsValidUri(const grpc_uri* uri) const override {
+    if (GPR_UNLIKELY(0 != strcmp(uri->authority, ""))) {
       gpr_log(GPR_ERROR, "authority based dns uri's not supported");
-      return OrphanablePtr<Resolver>(nullptr);
+      return false;
     }
+    return true;
+  }
+
+  OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
+    if (!IsValidUri(args.uri)) return nullptr;
     return OrphanablePtr<Resolver>(New<NativeDnsResolver>(std::move(args)));
   }
 

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

@@ -89,9 +89,15 @@ FakeResolver::FakeResolver(ResolverArgs args)
     : Resolver(args.combiner, std::move(args.result_handler)) {
   GRPC_CLOSURE_INIT(&reresolution_closure_, ReturnReresolutionResult, this,
                     grpc_combiner_scheduler(combiner()));
-  channel_args_ = grpc_channel_args_copy(args.args);
   FakeResolverResponseGenerator* response_generator =
       FakeResolverResponseGenerator::GetFromArgs(args.args);
+  // Channels sharing the same subchannels may have different resolver response
+  // generators. If we don't remove this arg, subchannel pool will create new
+  // subchannels for the same address instead of reusing existing ones because
+  // of different values of this channel arg.
+  const char* args_to_remove[] = {GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR};
+  channel_args_ = grpc_channel_args_copy_and_remove(
+      args.args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove));
   if (response_generator != nullptr) {
     response_generator->resolver_ = this;
     if (response_generator->has_result_) {
@@ -315,6 +321,8 @@ namespace {
 
 class FakeResolverFactory : public ResolverFactory {
  public:
+  bool IsValidUri(const grpc_uri* uri) const override { return true; }
+
   OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
     return OrphanablePtr<Resolver>(New<FakeResolver>(std::move(args)));
   }

src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.cc

@@ -80,24 +80,23 @@ void SockaddrResolver::StartLocked() {
 
 void DoNothing(void* ignored) {}
 
-OrphanablePtr<Resolver> CreateSockaddrResolver(
-    ResolverArgs args,
-    bool parse(const grpc_uri* uri, grpc_resolved_address* dst)) {
-  if (0 != strcmp(args.uri->authority, "")) {
+bool ParseUri(const grpc_uri* uri,
+              bool parse(const grpc_uri* uri, grpc_resolved_address* dst),
+              ServerAddressList* addresses) {
+  if (0 != strcmp(uri->authority, "")) {
     gpr_log(GPR_ERROR, "authority-based URIs not supported by the %s scheme",
-            args.uri->scheme);
-    return nullptr;
+            uri->scheme);
+    return false;
   }
   // Construct addresses.
   grpc_slice path_slice =
-      grpc_slice_new(args.uri->path, strlen(args.uri->path), DoNothing);
+      grpc_slice_new(uri->path, strlen(uri->path), DoNothing);
   grpc_slice_buffer path_parts;
   grpc_slice_buffer_init(&path_parts);
   grpc_slice_split(path_slice, ",", &path_parts);
-  ServerAddressList addresses;
   bool errors_found = false;
   for (size_t i = 0; i < path_parts.count; i++) {
-    grpc_uri ith_uri = *args.uri;
+    grpc_uri ith_uri = *uri;
     UniquePtr<char> part_str(grpc_slice_to_c_string(path_parts.slices[i]));
     ith_uri.path = part_str.get();
     grpc_resolved_address addr;
@@ -105,13 +104,20 @@ OrphanablePtr<Resolver> CreateSockaddrResolver(
       errors_found = true;
       break;
     }
-    addresses.emplace_back(addr, nullptr /* args */);
+    if (addresses != nullptr) {
+      addresses->emplace_back(addr, nullptr /* args */);
+    }
   }
   grpc_slice_buffer_destroy_internal(&path_parts);
   grpc_slice_unref_internal(path_slice);
-  if (errors_found) {
-    return OrphanablePtr<Resolver>(nullptr);
-  }
+  return !errors_found;
+}
+
+OrphanablePtr<Resolver> CreateSockaddrResolver(
+    ResolverArgs args,
+    bool parse(const grpc_uri* uri, grpc_resolved_address* dst)) {
+  ServerAddressList addresses;
+  if (!ParseUri(args.uri, parse, &addresses)) return nullptr;
   // Instantiate resolver.
   return OrphanablePtr<Resolver>(
       New<SockaddrResolver>(std::move(addresses), std::move(args)));
@@ -119,6 +125,10 @@ OrphanablePtr<Resolver> CreateSockaddrResolver(
 
 class IPv4ResolverFactory : public ResolverFactory {
  public:
+  bool IsValidUri(const grpc_uri* uri) const override {
+    return ParseUri(uri, grpc_parse_ipv4, nullptr);
+  }
+
   OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
     return CreateSockaddrResolver(std::move(args), grpc_parse_ipv4);
   }
@@ -128,6 +138,10 @@ class IPv4ResolverFactory : public ResolverFactory {
 
 class IPv6ResolverFactory : public ResolverFactory {
  public:
+  bool IsValidUri(const grpc_uri* uri) const override {
+    return ParseUri(uri, grpc_parse_ipv6, nullptr);
+  }
+
   OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
     return CreateSockaddrResolver(std::move(args), grpc_parse_ipv6);
   }
@@ -138,6 +152,10 @@ class IPv6ResolverFactory : public ResolverFactory {
 #ifdef GRPC_HAVE_UNIX_SOCKET
 class UnixResolverFactory : public ResolverFactory {
  public:
+  bool IsValidUri(const grpc_uri* uri) const override {
+    return ParseUri(uri, grpc_parse_unix, nullptr);
+  }
+
   OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
     return CreateSockaddrResolver(std::move(args), grpc_parse_unix);
   }

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

@@ -47,6 +47,10 @@ struct ResolverArgs {
 
 class ResolverFactory {
  public:
+  /// Returns a bool indicating whether the input uri is valid to create a
+  /// resolver.
+  virtual bool IsValidUri(const grpc_uri* uri) const GRPC_ABSTRACT;
+
   /// Returns a new resolver instance.
   virtual OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const
       GRPC_ABSTRACT;

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

@@ -132,6 +132,17 @@ ResolverFactory* ResolverRegistry::LookupResolverFactory(const char* scheme) {
   return g_state->LookupResolverFactory(scheme);
 }
 
+bool ResolverRegistry::IsValidTarget(const char* target) {
+  grpc_uri* uri = nullptr;
+  char* canonical_target = nullptr;
+  ResolverFactory* factory =
+      g_state->FindResolverFactory(target, &uri, &canonical_target);
+  bool result = factory == nullptr ? false : factory->IsValidUri(uri);
+  grpc_uri_destroy(uri);
+  gpr_free(canonical_target);
+  return result;
+}
+
 OrphanablePtr<Resolver> ResolverRegistry::CreateResolver(
     const char* target, const grpc_channel_args* args,
     grpc_pollset_set* pollset_set, grpc_combiner* combiner,

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

@@ -50,6 +50,9 @@ class ResolverRegistry {
     static void RegisterResolverFactory(UniquePtr<ResolverFactory> factory);
   };
 
+  /// Checks whether the user input \a target is valid to create a resolver.
+  static bool IsValidTarget(const char* target);
+
   /// Creates a resolver given \a target.
   /// First tries to parse \a target as a URI. If this succeeds, tries
   /// to locate a registered resolver factory based on the URI scheme.

src/core/lib/gprpp/host_port.cc

@@ -44,7 +44,10 @@ int JoinHostPort(UniquePtr<char>* out, const char* host, int port) {
   return ret;
 }
 
-bool SplitHostPort(StringView name, StringView* host, StringView* port) {
+namespace {
+bool DoSplitHostPort(StringView name, StringView* host, StringView* port,
+                     bool* has_port) {
+  *has_port = false;
   if (name[0] == '[') {
     /* Parse a bracketed host, typically an IPv6 literal. */
     const size_t rbracket = name.find(']', 1);
@@ -58,6 +61,7 @@ bool SplitHostPort(StringView name, StringView* host, StringView* port) {
     } else if (name[rbracket + 1] == ':') {
       /* ]:<port?> */
       *port = name.substr(rbracket + 2, name.size() - rbracket - 2);
+      *has_port = true;
     } else {
       /* ]<invalid> */
       return false;
@@ -76,6 +80,7 @@ bool SplitHostPort(StringView name, StringView* host, StringView* port) {
       /* Exactly 1 colon.  Split into host:port. */
       *host = name.substr(0, colon);
       *port = name.substr(colon + 1, name.size() - colon - 1);
+      *has_port = true;
     } else {
       /* 0 or 2+ colons.  Bare hostname or IPv6 litearal. */
       *host = name;
@@ -84,6 +89,12 @@ bool SplitHostPort(StringView name, StringView* host, StringView* port) {
   }
   return true;
 }
+}  // namespace
+
+bool SplitHostPort(StringView name, StringView* host, StringView* port) {
+  bool unused;
+  return DoSplitHostPort(name, host, port, &unused);
+}
 
 bool SplitHostPort(StringView name, UniquePtr<char>* host,
                    UniquePtr<char>* port) {
@@ -91,12 +102,14 @@ bool SplitHostPort(StringView name, UniquePtr<char>* host,
   GPR_DEBUG_ASSERT(port != nullptr && *port == nullptr);
   StringView host_view;
   StringView port_view;
-  const bool ret = SplitHostPort(name, &host_view, &port_view);
+  bool has_port;
+  const bool ret = DoSplitHostPort(name, &host_view, &port_view, &has_port);
   if (ret) {
-    // We always set the host, but port is set only when it's non-empty,
-    // to remain backward compatible with the old split_host_port API.
+    // We always set the host, but port is set only when DoSplitHostPort find a
+    // port in the string, to remain backward compatible with the old
+    // gpr_split_host_port API.
     *host = host_view.dup();
-    if (!port_view.empty()) {
+    if (has_port) {
       *port = port_view.dup();
     }
   }

src/core/lib/slice/slice_buffer.cc

@@ -262,9 +262,9 @@ void grpc_slice_buffer_move_into(grpc_slice_buffer* src,
   src->length = 0;
 }
 
+template <bool incref>
 static void slice_buffer_move_first_maybe_ref(grpc_slice_buffer* src, size_t n,
-                                              grpc_slice_buffer* dst,
-                                              bool incref) {
+                                              grpc_slice_buffer* dst) {
   GPR_ASSERT(src->length >= n);
   if (src->length == n) {
     grpc_slice_buffer_move_into(src, dst);
@@ -304,12 +304,12 @@ static void slice_buffer_move_first_maybe_ref(grpc_slice_buffer* src, size_t n,
 
 void grpc_slice_buffer_move_first(grpc_slice_buffer* src, size_t n,
                                   grpc_slice_buffer* dst) {
-  slice_buffer_move_first_maybe_ref(src, n, dst, true);
+  slice_buffer_move_first_maybe_ref<true>(src, n, dst);
 }
 
 void grpc_slice_buffer_move_first_no_ref(grpc_slice_buffer* src, size_t n,
                                          grpc_slice_buffer* dst) {
-  slice_buffer_move_first_maybe_ref(src, n, dst, false);
+  slice_buffer_move_first_maybe_ref<false>(src, n, dst);
 }
 
 void grpc_slice_buffer_move_first_into_buffer(grpc_slice_buffer* src, size_t n,

src/cpp/client/generic_stub.cc

@@ -27,11 +27,10 @@ namespace grpc_impl {
 namespace {
 std::unique_ptr<grpc::GenericClientAsyncReaderWriter> CallInternal(
     grpc::ChannelInterface* channel, grpc::ClientContext* context,
-    const grpc::string& method, grpc::CompletionQueue* cq, bool start,
-    void* tag) {
+    const grpc::string& method, CompletionQueue* cq, bool start, void* tag) {
   return std::unique_ptr<grpc::GenericClientAsyncReaderWriter>(
-      grpc::internal::ClientAsyncReaderWriterFactory<grpc::ByteBuffer,
-                                                     grpc::ByteBuffer>::
+      internal::ClientAsyncReaderWriterFactory<grpc::ByteBuffer,
+                                               grpc::ByteBuffer>::
           Create(channel, cq,
                  grpc::internal::RpcMethod(
                      method.c_str(), grpc::internal::RpcMethod::BIDI_STREAMING),
@@ -43,14 +42,14 @@ std::unique_ptr<grpc::GenericClientAsyncReaderWriter> CallInternal(
 // begin a call to a named method
 std::unique_ptr<grpc::GenericClientAsyncReaderWriter> GenericStub::Call(
     grpc::ClientContext* context, const grpc::string& method,
-    grpc::CompletionQueue* cq, void* tag) {
+    CompletionQueue* cq, void* tag) {
   return CallInternal(channel_.get(), context, method, cq, true, tag);
 }
 
 // setup a call to a named method
 std::unique_ptr<grpc::GenericClientAsyncReaderWriter> GenericStub::PrepareCall(
     grpc::ClientContext* context, const grpc::string& method,
-    grpc::CompletionQueue* cq) {
+    CompletionQueue* cq) {
   return CallInternal(channel_.get(), context, method, cq, false, nullptr);
 }
 
@@ -59,21 +58,20 @@ std::unique_ptr<grpc::GenericClientAsyncResponseReader>
 GenericStub::PrepareUnaryCall(grpc::ClientContext* context,
                               const grpc::string& method,
                               const grpc::ByteBuffer& request,
-                              grpc::CompletionQueue* cq) {
+                              CompletionQueue* cq) {
   return std::unique_ptr<grpc::GenericClientAsyncResponseReader>(
-      grpc::internal::ClientAsyncResponseReaderFactory<
-          grpc::ByteBuffer>::Create(channel_.get(), cq,
-                                    grpc::internal::RpcMethod(
-                                        method.c_str(),
-                                        grpc::internal::RpcMethod::NORMAL_RPC),
-                                    context, request, false));
+      internal::ClientAsyncResponseReaderFactory<grpc::ByteBuffer>::Create(
+          channel_.get(), cq,
+          grpc::internal::RpcMethod(method.c_str(),
+                                    grpc::internal::RpcMethod::NORMAL_RPC),
+          context, request, false));
 }
 
 void GenericStub::experimental_type::UnaryCall(
     grpc::ClientContext* context, const grpc::string& method,
     const grpc::ByteBuffer* request, grpc::ByteBuffer* response,
     std::function<void(grpc::Status)> on_completion) {
-  grpc::internal::CallbackUnaryCall(
+  internal::CallbackUnaryCall(
       stub_->channel_.get(),
       grpc::internal::RpcMethod(method.c_str(),
                                 grpc::internal::RpcMethod::NORMAL_RPC),
@@ -82,9 +80,9 @@ void GenericStub::experimental_type::UnaryCall(
 
 void GenericStub::experimental_type::PrepareBidiStreamingCall(
     grpc::ClientContext* context, const grpc::string& method,
-    grpc::experimental::ClientBidiReactor<grpc::ByteBuffer, grpc::ByteBuffer>*
+    experimental::ClientBidiReactor<grpc::ByteBuffer, grpc::ByteBuffer>*
         reactor) {
-  grpc::internal::ClientCallbackReaderWriterFactory<
+  internal::ClientCallbackReaderWriterFactory<
       grpc::ByteBuffer,
       grpc::ByteBuffer>::Create(stub_->channel_.get(),
                                 grpc::internal::RpcMethod(

src/cpp/server/async_generic_service.cc

@@ -24,8 +24,8 @@ namespace grpc {
 
 void AsyncGenericService::RequestCall(
     GenericServerContext* ctx, GenericServerAsyncReaderWriter* reader_writer,
-    CompletionQueue* call_cq, ServerCompletionQueue* notification_cq,
-    void* tag) {
+    ::grpc_impl::CompletionQueue* call_cq,
+    ::grpc_impl::ServerCompletionQueue* notification_cq, void* tag) {
   server_->RequestAsyncGenericCall(ctx, reader_writer, call_cq, notification_cq,
                                    tag);
 }

src/cpp/server/health/default_health_check_service.h

@@ -28,6 +28,7 @@
 #include <grpcpp/health_check_service_interface.h>
 #include <grpcpp/impl/codegen/async_generic_service.h>
 #include <grpcpp/impl/codegen/async_unary_call.h>
+#include <grpcpp/impl/codegen/completion_queue.h>
 #include <grpcpp/impl/codegen/service_type.h>
 #include <grpcpp/support/byte_buffer.h>
 

src/cpp/server/server_builder.cc

@@ -69,14 +69,14 @@ ServerBuilder::~ServerBuilder() {
   }
 }
 
-std::unique_ptr<grpc::ServerCompletionQueue> ServerBuilder::AddCompletionQueue(
+std::unique_ptr<ServerCompletionQueue> ServerBuilder::AddCompletionQueue(
     bool is_frequently_polled) {
-  grpc::ServerCompletionQueue* cq = new grpc::ServerCompletionQueue(
+  ServerCompletionQueue* cq = new ServerCompletionQueue(
       GRPC_CQ_NEXT,
       is_frequently_polled ? GRPC_CQ_DEFAULT_POLLING : GRPC_CQ_NON_LISTENING,
       nullptr);
   cqs_.push_back(cq);
-  return std::unique_ptr<grpc::ServerCompletionQueue>(cq);
+  return std::unique_ptr<ServerCompletionQueue>(cq);
 }
 
 ServerBuilder& ServerBuilder::RegisterService(grpc::Service* service) {
@@ -266,10 +266,9 @@ std::unique_ptr<grpc::Server> ServerBuilder::BuildAndStart() {
   // This is different from the completion queues added to the server via
   // ServerBuilder's AddCompletionQueue() method (those completion queues
   // are in 'cqs_' member variable of ServerBuilder object)
-  std::shared_ptr<std::vector<std::unique_ptr<grpc::ServerCompletionQueue>>>
-      sync_server_cqs(
-          std::make_shared<
-              std::vector<std::unique_ptr<grpc::ServerCompletionQueue>>>());
+  std::shared_ptr<std::vector<std::unique_ptr<ServerCompletionQueue>>>
+      sync_server_cqs(std::make_shared<
+                      std::vector<std::unique_ptr<ServerCompletionQueue>>>());
 
   bool has_frequently_polled_cqs = false;
   for (auto it = cqs_.begin(); it != cqs_.end(); ++it) {
@@ -298,7 +297,7 @@ std::unique_ptr<grpc::Server> ServerBuilder::BuildAndStart() {
     // Create completion queues to listen to incoming rpc requests
     for (int i = 0; i < sync_server_settings_.num_cqs; i++) {
       sync_server_cqs->emplace_back(
-          new grpc::ServerCompletionQueue(GRPC_CQ_NEXT, polling_type, nullptr));
+          new ServerCompletionQueue(GRPC_CQ_NEXT, polling_type, nullptr));
     }
   }
 

src/cpp/server/server_context.cc

@@ -45,8 +45,7 @@ class ServerContext::CompletionOp final
  public:
   // initial refs: one in the server context, one in the cq
   // must ref the call before calling constructor and after deleting this
-  CompletionOp(::grpc::internal::Call* call,
-               ::grpc::internal::ServerReactor* reactor)
+  CompletionOp(::grpc::internal::Call* call, internal::ServerReactor* reactor)
       : call_(*call),
         reactor_(reactor),
         has_tag_(false),
@@ -152,7 +151,7 @@ class ServerContext::CompletionOp final
   }
 
   ::grpc::internal::Call call_;
-  ::grpc::internal::ServerReactor* const reactor_;
+  internal::ServerReactor* const reactor_;
   bool has_tag_;
   void* tag_;
   void* core_cq_tag_;
@@ -294,9 +293,9 @@ void ServerContext::Clear() {
   }
 }
 
-void ServerContext::BeginCompletionOp(
-    ::grpc::internal::Call* call, std::function<void(bool)> callback,
-    ::grpc::internal::ServerReactor* reactor) {
+void ServerContext::BeginCompletionOp(::grpc::internal::Call* call,
+                                      std::function<void(bool)> callback,
+                                      internal::ServerReactor* reactor) {
   GPR_ASSERT(!completion_op_);
   if (rpc_info_) {
     rpc_info_->Ref();

src/csharp/Grpc.Core.Api/Grpc.Core.Api.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="..\Grpc.Core\Common.csproj.include" />
 
@@ -11,6 +11,7 @@
     <PackageProjectUrl>https://github.com/grpc/grpc</PackageProjectUrl>
     <PackageTags>gRPC RPC HTTP/2</PackageTags>
     <VersionPrefix>$(GrpcCsharpVersion)</VersionPrefix>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <PropertyGroup>

src/csharp/Grpc.Core.Api/Metadata.cs

@@ -17,8 +17,9 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Runtime.InteropServices;
 using System.Text;
-using System.Text.RegularExpressions;
+using Grpc.Core.Api.Utils;
 
 using Grpc.Core.Utils;
 
@@ -345,15 +346,31 @@ namespace Grpc.Core
             /// Creates a binary value or ascii value metadata entry from data received from the native layer.
             /// We trust C core to give us well-formed data, so we don't perform any checks or defensive copying.
             /// </summary>
-            internal static Entry CreateUnsafe(string key, byte[] valueBytes)
+            internal static Entry CreateUnsafe(string key, IntPtr source, int length)
             {
                 if (HasBinaryHeaderSuffix(key))
                 {
-                    return new Entry(key, null, valueBytes);
+                    byte[] arr;
+                    if (length == 0)
+                    {
+                        arr = EmptyByteArray;
+                    }
+                    else
+                    {   // create a local copy in a fresh array
+                        arr = new byte[length];
+                        Marshal.Copy(source, arr, 0, length);
+                    }
+                    return new Entry(key, null, arr);
+                }
+                else
+                {
+                    string s = EncodingASCII.GetString(source, length);
+                    return new Entry(key, s, null);
                 }
-                return new Entry(key, EncodingASCII.GetString(valueBytes), null);
             }
 
+            static readonly byte[] EmptyByteArray = new byte[0];
+
             private static string NormalizeKey(string key)
             {
                 GrpcPreconditions.CheckNotNull(key, "key");

src/csharp/Grpc.Core.Api/Utils/EncodingExtensions.cs

@@ -0,0 +1,54 @@
+#region Copyright notice and license
+// Copyright 2019 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#endregion
+
+using System;
+using System.Runtime.CompilerServices;
+using System.Text;
+
+namespace Grpc.Core.Api.Utils
+{
+
+    internal static class EncodingExtensions
+    {
+#if NET45 // back-fill over a method missing in NET45
+        /// <summary>
+        /// Converts <c>byte*</c> pointing to an encoded byte array to a <c>string</c> using the provided <c>Encoding</c>.
+        /// </summary>
+        public static unsafe string GetString(this Encoding encoding, byte* source, int byteCount)
+        {
+            if (byteCount == 0) return ""; // most callers will have already checked, but: make sure
+
+            // allocate a right-sized string and decode into it
+            int charCount = encoding.GetCharCount(source, byteCount);
+            string s = new string('\0', charCount);
+            fixed (char* cPtr = s)
+            {
+                encoding.GetChars(source, byteCount, cPtr, charCount);
+            }
+            return s;
+        }
+#endif
+        /// <summary>
+        /// Converts <c>IntPtr</c> pointing to a encoded byte array to a <c>string</c> using the provided <c>Encoding</c>.
+        /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static unsafe string GetString(this Encoding encoding, IntPtr ptr, int len)
+        {
+            return len == 0 ? "" : encoding.GetString((byte*)ptr.ToPointer(), len);
+        }
+    }
+
+}

src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="..\Grpc.Core\Common.csproj.include" />
 
@@ -6,6 +6,7 @@
     <TargetFrameworks>net45;netcoreapp2.1</TargetFrameworks>
     <OutputType>Exe</OutputType>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">

src/csharp/Grpc.Core.Tests/Internal/WellKnownStringsTest.cs

@@ -0,0 +1,62 @@
+#region Copyright notice and license
+// Copyright 2019 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#endregion
+
+using System.Text;
+using Grpc.Core.Internal;
+using NUnit.Framework;
+
+namespace Grpc.Core.Internal.Tests
+{
+    public class WellKnownStringsTest
+    {
+        [Test]
+        [TestCase("", true)]
+        [TestCase("u", false)]
+        [TestCase("us", false)]
+        [TestCase("use", false)]
+        [TestCase("user", false)]
+        [TestCase("user-", false)]
+        [TestCase("user-a", false)]
+        [TestCase("user-ag", false)]
+        [TestCase("user-age", false)]
+        [TestCase("user-agent", true)]
+        [TestCase("user-agent ", false)]
+        [TestCase("useragent ", false)]
+        [TestCase("User-Agent", false)]
+        [TestCase("sdlkfjlskjfdlkjs;lfdksflsdfkh skjdfh sdkfhskdhf skjfhk sdhjkjh", false)]
+
+        // test for endianness snafus (reversed in segments)
+        [TestCase("ega-resutn", false)]
+        public unsafe void TestWellKnownStrings(string input, bool expected)
+        {
+            // create a copy of the data; no cheating!
+            byte[] bytes = Encoding.ASCII.GetBytes(input);
+            fixed(byte* ptr = bytes)
+            {
+                string result = WellKnownStrings.TryIdentify(ptr, bytes.Length);
+                if (expected) Assert.AreEqual(input, result);
+                else Assert.IsNull(result);
+
+                if (expected)
+                {
+                    // try again, and check we get the same instance
+                    string again = WellKnownStrings.TryIdentify(ptr, bytes.Length);
+                    Assert.AreSame(result, again);
+                }
+            }
+        }
+    }
+}

src/csharp/Grpc.Core.Tests/MetadataTest.cs

@@ -111,25 +111,31 @@ namespace Grpc.Core.Tests
         }
 
         [Test]
-        public void Entry_CreateUnsafe_Ascii()
+        public unsafe void Entry_CreateUnsafe_Ascii()
         {
             var bytes = new byte[] { (byte)'X', (byte)'y' };
-            var entry = Metadata.Entry.CreateUnsafe("abc", bytes);
-            Assert.IsFalse(entry.IsBinary);
-            Assert.AreEqual("abc", entry.Key);
-            Assert.AreEqual("Xy", entry.Value);
-            CollectionAssert.AreEqual(bytes, entry.ValueBytes);
+            fixed (byte* ptr = bytes)
+            {
+                var entry = Metadata.Entry.CreateUnsafe("abc", new IntPtr(ptr), bytes.Length);
+                Assert.IsFalse(entry.IsBinary);
+                Assert.AreEqual("abc", entry.Key);
+                Assert.AreEqual("Xy", entry.Value);
+                CollectionAssert.AreEqual(bytes, entry.ValueBytes);
+            }
         }
 
         [Test]
-        public void Entry_CreateUnsafe_Binary()
+        public unsafe void Entry_CreateUnsafe_Binary()
         {
             var bytes = new byte[] { 1, 2, 3 };
-            var entry = Metadata.Entry.CreateUnsafe("abc-bin", bytes);
-            Assert.IsTrue(entry.IsBinary);
-            Assert.AreEqual("abc-bin", entry.Key);
-            Assert.Throws(typeof(InvalidOperationException), () => { var v = entry.Value; });
-            CollectionAssert.AreEqual(bytes, entry.ValueBytes);
+            fixed (byte* ptr = bytes)
+            {
+                var entry = Metadata.Entry.CreateUnsafe("abc-bin", new IntPtr(ptr), bytes.Length);
+                Assert.IsTrue(entry.IsBinary);
+                Assert.AreEqual("abc-bin", entry.Key);
+                Assert.Throws(typeof(InvalidOperationException), () => { var v = entry.Value; });
+                CollectionAssert.AreEqual(bytes, entry.ValueBytes);
+            }
         }
 
         [Test]

src/csharp/Grpc.Core/Grpc.Core.csproj

@@ -100,6 +100,8 @@
 
   <ItemGroup>
     <PackageReference Include="System.Interactive.Async" Version="3.2.0" />
+    <!-- System.Buffers *may* come in transitively, but: we can *always* use ArrayPool -->
+    <PackageReference Include="System.Buffers" Version="4.5.0" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net45' ">

src/csharp/Grpc.Core/Internal/CallSafeHandle.cs

@@ -21,6 +21,7 @@ using System.Text;
 using Grpc.Core;
 using Grpc.Core.Utils;
 using Grpc.Core.Profiling;
+using System.Buffers;
 
 namespace Grpc.Core.Internal
 {
@@ -134,9 +135,48 @@ namespace Grpc.Core.Internal
             {
                 var ctx = completionQueue.CompletionRegistry.RegisterBatchCompletion(CompletionHandler_ISendStatusFromServerCompletionCallback, callback);
                 var optionalPayloadLength = optionalPayload != null ? new UIntPtr((ulong)optionalPayload.Length) : UIntPtr.Zero;
-                var statusDetailBytes = MarshalUtils.GetBytesUTF8(status.Detail);
-                Native.grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, statusDetailBytes, new UIntPtr((ulong)statusDetailBytes.Length), metadataArray, sendEmptyInitialMetadata ? 1 : 0,
-                    optionalPayload, optionalPayloadLength, writeFlags).CheckOk();
+
+                const int MaxStackAllocBytes = 256;
+                int maxBytes = MarshalUtils.GetMaxByteCountUTF8(status.Detail);
+                if (maxBytes > MaxStackAllocBytes)
+                {
+                    // pay the extra to get the *actual* size; this could mean that
+                    // it ends up fitting on the stack after all, but even if not
+                    // it will mean that we ask for a *much* smaller buffer
+                    maxBytes = MarshalUtils.GetByteCountUTF8(status.Detail);
+                }
+
+                unsafe
+                {
+                    if (maxBytes <= MaxStackAllocBytes)
+                    {   // for small status, we can encode on the stack without touching arrays
+                        // note: if init-locals is disabled, it would be more efficient
+                        // to just stackalloc[MaxStackAllocBytes]; but by default, since we
+                        // expect this to be small and it needs to wipe, just use maxBytes
+                        byte* ptr = stackalloc byte[maxBytes];
+                        int statusBytes = MarshalUtils.GetBytesUTF8(status.Detail, ptr, maxBytes);
+                        Native.grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, new IntPtr(ptr), new UIntPtr((ulong)statusBytes), metadataArray, sendEmptyInitialMetadata ? 1 : 0,
+                            optionalPayload, optionalPayloadLength, writeFlags).CheckOk();
+                    }
+                    else
+                    {   // for larger status (rare), rent a buffer from the pool and
+                        // use that for encoding
+                        var statusBuffer = ArrayPool<byte>.Shared.Rent(maxBytes);
+                        try
+                        {
+                            fixed (byte* ptr = statusBuffer)
+                            {
+                                int statusBytes = MarshalUtils.GetBytesUTF8(status.Detail, ptr, maxBytes);
+                                Native.grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, new IntPtr(ptr), new UIntPtr((ulong)statusBytes), metadataArray, sendEmptyInitialMetadata ? 1 : 0,
+                                  optionalPayload, optionalPayloadLength, writeFlags).CheckOk();
+                            }
+                        }
+                        finally
+                        {
+                            ArrayPool<byte>.Shared.Return(statusBuffer);
+                        }
+                    }
+                }
             }
         }
 

src/csharp/Grpc.Core/Internal/MarshalUtils.cs

@@ -17,8 +17,9 @@
 #endregion
 
 using System;
-using System.Runtime.InteropServices;
+using System.Runtime.CompilerServices;
 using System.Text;
+using Grpc.Core.Api.Utils;
 
 namespace Grpc.Core.Internal
 {
@@ -32,34 +33,41 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Converts <c>IntPtr</c> pointing to a UTF-8 encoded byte array to <c>string</c>.
         /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static string PtrToStringUTF8(IntPtr ptr, int len)
         {
-            if (len == 0)
+            return EncodingUTF8.GetString(ptr, len);
+        }
+
+        /// <summary>
+        /// UTF-8 encodes the given string into a buffer of sufficient size
+        /// </summary>
+        public static unsafe int GetBytesUTF8(string str, byte* destination, int destinationLength)
+        {
+            int charCount = str.Length;
+            if (charCount == 0) return 0;
+            fixed (char* source = str)
             {
-                return "";
+                return EncodingUTF8.GetBytes(source, charCount, destination, destinationLength);
             }
-
-            // TODO(jtattermusch): once Span dependency is added,
-            // use Span-based API to decode the string without copying the buffer.
-            var bytes = new byte[len];
-            Marshal.Copy(ptr, bytes, 0, len);
-            return EncodingUTF8.GetString(bytes);
         }
 
         /// <summary>
-        /// Returns byte array containing UTF-8 encoding of given string.
+        /// Returns the maximum number of bytes required to encode a given string.
         /// </summary>
-        public static byte[] GetBytesUTF8(string str)
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int GetMaxByteCountUTF8(string str)
         {
-            return EncodingUTF8.GetBytes(str);
+            return EncodingUTF8.GetMaxByteCount(str.Length);
         }
 
         /// <summary>
-        /// Get string from a UTF8 encoded byte array.
+        /// Returns the actual number of bytes required to encode a given string.
         /// </summary>
-        public static string GetStringUTF8(byte[] bytes)
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int GetByteCountUTF8(string str)
         {
-            return EncodingUTF8.GetString(bytes);
+            return EncodingUTF8.GetByteCount(str);
         }
     }
 }

src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs

@@ -15,8 +15,7 @@
 #endregion
 using System;
 using System.Runtime.InteropServices;
-using System.Threading.Tasks;
-using Grpc.Core.Profiling;
+using System.Text;
 
 namespace Grpc.Core.Internal
 {
@@ -66,12 +65,13 @@ namespace Grpc.Core.Internal
                 var index = new UIntPtr(i);
                 UIntPtr keyLen;
                 IntPtr keyPtr = Native.grpcsharp_metadata_array_get_key(metadataArray, index, out keyLen);
-                string key = Marshal.PtrToStringAnsi(keyPtr, (int)keyLen.ToUInt32());
+                int keyLen32 = checked((int)keyLen.ToUInt32());
+                string key = WellKnownStrings.TryIdentify(keyPtr, keyLen32)
+                    ?? Marshal.PtrToStringAnsi(keyPtr, keyLen32);
                 UIntPtr valueLen;
                 IntPtr valuePtr = Native.grpcsharp_metadata_array_get_value(metadataArray, index, out valueLen);
-                var bytes = new byte[valueLen.ToUInt64()];
-                Marshal.Copy(valuePtr, bytes, 0, bytes.Length);
-                metadata.Add(Metadata.Entry.CreateUnsafe(key, bytes));
+                int len32 = checked((int)valueLen.ToUInt64());
+                metadata.Add(Metadata.Entry.CreateUnsafe(key, valuePtr, len32));
             }
             return metadata;
         }

src/csharp/Grpc.Core/Internal/NativeMethods.Generated.cs

@@ -469,7 +469,7 @@ namespace Grpc.Core.Internal
             public delegate CallError grpcsharp_call_start_duplex_streaming_delegate(CallSafeHandle call, BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray, CallFlags metadataFlags);
             public delegate CallError grpcsharp_call_send_message_delegate(CallSafeHandle call, BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, WriteFlags writeFlags, int sendEmptyInitialMetadata);
             public delegate CallError grpcsharp_call_send_close_from_client_delegate(CallSafeHandle call, BatchContextSafeHandle ctx);
-            public delegate CallError grpcsharp_call_send_status_from_server_delegate(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, byte[] statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
+            public delegate CallError grpcsharp_call_send_status_from_server_delegate(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, IntPtr statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
             public delegate CallError grpcsharp_call_recv_message_delegate(CallSafeHandle call, BatchContextSafeHandle ctx);
             public delegate CallError grpcsharp_call_recv_initial_metadata_delegate(CallSafeHandle call, BatchContextSafeHandle ctx);
             public delegate CallError grpcsharp_call_start_serverside_delegate(CallSafeHandle call, BatchContextSafeHandle ctx);
@@ -637,7 +637,7 @@ namespace Grpc.Core.Internal
             public static extern CallError grpcsharp_call_send_close_from_client(CallSafeHandle call, BatchContextSafeHandle ctx);
             
             [DllImport(ImportName)]
-            public static extern CallError grpcsharp_call_send_status_from_server(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, byte[] statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
+            public static extern CallError grpcsharp_call_send_status_from_server(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, IntPtr statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
             
             [DllImport(ImportName)]
             public static extern CallError grpcsharp_call_recv_message(CallSafeHandle call, BatchContextSafeHandle ctx);
@@ -933,7 +933,7 @@ namespace Grpc.Core.Internal
             public static extern CallError grpcsharp_call_send_close_from_client(CallSafeHandle call, BatchContextSafeHandle ctx);
             
             [DllImport(ImportName)]
-            public static extern CallError grpcsharp_call_send_status_from_server(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, byte[] statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
+            public static extern CallError grpcsharp_call_send_status_from_server(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, IntPtr statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
             
             [DllImport(ImportName)]
             public static extern CallError grpcsharp_call_recv_message(CallSafeHandle call, BatchContextSafeHandle ctx);

src/csharp/Grpc.Core/Internal/WellKnownStrings.cs

@@ -0,0 +1,92 @@
+#region Copyright notice and license
+// Copyright 2019 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#endregion
+
+using System;
+using System.Runtime.CompilerServices;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Utility type for identifying "well-known" strings (i.e. headers/keys etc that
+    /// we expect to see frequently, and don't want to allocate lots of copies of)
+    /// </summary>
+    internal static class WellKnownStrings
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static unsafe ulong Coerce64(byte* value)
+        {
+            return *(ulong*)value;
+        }
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static unsafe uint Coerce32(byte* value)
+        {
+            return *(uint*)value;
+        }
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static unsafe ushort Coerce16(byte* value)
+        {
+            return *(ushort*)value;
+        }
+
+
+        /// <summary>
+        /// Test whether the provided byte sequence is recognized as a well-known string; if
+        /// so, return a shared instance of that string; otherwise, return null
+        /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static unsafe string TryIdentify(IntPtr source, int length)
+        {
+            return TryIdentify((byte*)source.ToPointer(), length);
+        }
+
+        /// <summary>
+        /// Test whether the provided byte sequence is recognized as a well-known string; if
+        /// so, return a shared instance of that string; otherwise, return null
+        /// </summary>
+        public static unsafe string TryIdentify(byte* source, int length)
+        {
+            // note: the logic here is hard-coded to constants for optimal processing;
+            // refer to an ASCII/hex converter (and remember to reverse **segments** for little-endian)
+            if (BitConverter.IsLittleEndian) // this is a JIT intrinsic; branch removal happens on modern runtimes
+            {
+                switch (length)
+                {
+                    case 0: return "";
+                    case 10:
+                        switch(Coerce64(source))
+                        {
+                            case 0x6567612d72657375: return Coerce16(source + 8) == 0x746e ? "user-agent" : null;
+                        }
+                        break;
+                }
+            }
+            else
+            {
+                switch (length)
+                {
+                    case 0: return "";
+                    case 10:
+                        switch (Coerce64(source))
+                        {
+                            case 0x757365722d616765: return Coerce16(source + 8) == 0x6e74 ? "user-agent" : null;
+                        }
+                        break;
+                }
+            }
+            return null;
+        }
+    }
+}

src/csharp/Grpc.Microbenchmarks/Utf8Encode.cs

@@ -61,7 +61,7 @@ namespace Grpc.Microbenchmarks
             var native = NativeMethods.Get();
 
             // nop the native-call via reflection
-            NativeMethods.Delegates.grpcsharp_call_send_status_from_server_delegate nop = (CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, byte[] statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags) => {
+            NativeMethods.Delegates.grpcsharp_call_send_status_from_server_delegate nop = (CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, IntPtr statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags) => {
                 completionRegistry.Extract(ctx.Handle).OnComplete(true); // drain the dictionary as we go
                 return CallError.OK;
             };

src/csharp/tests.json

@@ -14,6 +14,7 @@
     "Grpc.Core.Internal.Tests.ReusableSliceBufferTest",
     "Grpc.Core.Internal.Tests.SliceTest",
     "Grpc.Core.Internal.Tests.TimespecTest",
+    "Grpc.Core.Internal.Tests.WellKnownStringsTest",
     "Grpc.Core.Tests.AppDomainUnloadTest",
     "Grpc.Core.Tests.AuthContextTest",
     "Grpc.Core.Tests.AuthPropertyTest",

templates/src/csharp/Grpc.Core/Internal/native_methods.include

@@ -31,7 +31,7 @@ native_method_signatures = [
     'CallError grpcsharp_call_start_duplex_streaming(CallSafeHandle call, BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray, CallFlags metadataFlags)',
     'CallError grpcsharp_call_send_message(CallSafeHandle call, BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, WriteFlags writeFlags, int sendEmptyInitialMetadata)',
     'CallError grpcsharp_call_send_close_from_client(CallSafeHandle call, BatchContextSafeHandle ctx)',
-    'CallError grpcsharp_call_send_status_from_server(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, byte[] statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags)',
+    'CallError grpcsharp_call_send_status_from_server(CallSafeHandle call, BatchContextSafeHandle ctx, StatusCode statusCode, IntPtr statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata, byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags)',
     'CallError grpcsharp_call_recv_message(CallSafeHandle call, BatchContextSafeHandle ctx)',
     'CallError grpcsharp_call_recv_initial_metadata(CallSafeHandle call, BatchContextSafeHandle ctx)',
     'CallError grpcsharp_call_start_serverside(CallSafeHandle call, BatchContextSafeHandle ctx)',
@@ -107,4 +107,4 @@ for signature in native_method_signatures:
   native_methods.append({'returntype': match.group(1), 'name': match.group(2), 'params': match.group(3), 'comment': match.group(4)})
 
 return list(native_methods)
-%></%def>
+%></%def>

test/core/gprpp/host_port_test.cc

@@ -71,7 +71,9 @@ static void test_split_host_port() {
   split_host_port_expect("", "", nullptr, true);
   split_host_port_expect("[a:b]", "a:b", nullptr, true);
   split_host_port_expect("1.2.3.4", "1.2.3.4", nullptr, true);
+  split_host_port_expect("0.0.0.0:", "0.0.0.0", "", true);
   split_host_port_expect("a:b:c::", "a:b:c::", nullptr, true);
+  split_host_port_expect("[a:b:c::]:", "a:b:c::", "", true);
   split_host_port_expect("[a:b]:30", "a:b", "30", true);
   split_host_port_expect("1.2.3.4:30", "1.2.3.4", "30", true);
   split_host_port_expect(":30", "", "30", true);

test/cpp/codegen/compiler_test_golden

@@ -32,6 +32,7 @@
 #include <grpcpp/impl/codegen/async_unary_call.h>
 #include <grpcpp/impl/codegen/client_callback.h>
 #include <grpcpp/impl/codegen/client_context.h>
+#include <grpcpp/impl/codegen/completion_queue.h>
 #include <grpcpp/impl/codegen/method_handler_impl.h>
 #include <grpcpp/impl/codegen/proto_utils.h>
 #include <grpcpp/impl/codegen/rpc_method.h>
@@ -336,7 +337,7 @@ class ServiceA final {
    public:
     ExperimentalWithCallbackMethod_MethodA1() {
       ::grpc::Service::experimental().MarkMethodCallback(0,
-        new ::grpc::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
+        new ::grpc_impl::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
           [this](::grpc::ServerContext* context,
                  const ::grpc::testing::Request* request,
                  ::grpc::testing::Response* response,
@@ -346,7 +347,7 @@ class ServiceA final {
     }
     void SetMessageAllocatorFor_MethodA1(
         ::grpc::experimental::MessageAllocator< ::grpc::testing::Request, ::grpc::testing::Response>* allocator) {
-      static_cast<::grpc::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>*>(
+      static_cast<::grpc_impl::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>*>(
           ::grpc::Service::experimental().GetHandler(0))
               ->SetMessageAllocator(allocator);
     }
@@ -367,7 +368,7 @@ class ServiceA final {
    public:
     ExperimentalWithCallbackMethod_MethodA2() {
       ::grpc::Service::experimental().MarkMethodCallback(1,
-        new ::grpc::internal::CallbackClientStreamingHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
+        new ::grpc_impl::internal::CallbackClientStreamingHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
           [this] { return this->MethodA2(); }));
     }
     ~ExperimentalWithCallbackMethod_MethodA2() override {
@@ -379,7 +380,7 @@ class ServiceA final {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
     virtual ::grpc::experimental::ServerReadReactor< ::grpc::testing::Request, ::grpc::testing::Response>* MethodA2() {
-      return new ::grpc::internal::UnimplementedReadReactor<
+      return new ::grpc_impl::internal::UnimplementedReadReactor<
         ::grpc::testing::Request, ::grpc::testing::Response>;}
   };
   template <class BaseClass>
@@ -389,7 +390,7 @@ class ServiceA final {
    public:
     ExperimentalWithCallbackMethod_MethodA3() {
       ::grpc::Service::experimental().MarkMethodCallback(2,
-        new ::grpc::internal::CallbackServerStreamingHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
+        new ::grpc_impl::internal::CallbackServerStreamingHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
           [this] { return this->MethodA3(); }));
     }
     ~ExperimentalWithCallbackMethod_MethodA3() override {
@@ -401,7 +402,7 @@ class ServiceA final {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
     virtual ::grpc::experimental::ServerWriteReactor< ::grpc::testing::Request, ::grpc::testing::Response>* MethodA3() {
-      return new ::grpc::internal::UnimplementedWriteReactor<
+      return new ::grpc_impl::internal::UnimplementedWriteReactor<
         ::grpc::testing::Request, ::grpc::testing::Response>;}
   };
   template <class BaseClass>
@@ -411,7 +412,7 @@ class ServiceA final {
    public:
     ExperimentalWithCallbackMethod_MethodA4() {
       ::grpc::Service::experimental().MarkMethodCallback(3,
-        new ::grpc::internal::CallbackBidiHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
+        new ::grpc_impl::internal::CallbackBidiHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
           [this] { return this->MethodA4(); }));
     }
     ~ExperimentalWithCallbackMethod_MethodA4() override {
@@ -423,7 +424,7 @@ class ServiceA final {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
     virtual ::grpc::experimental::ServerBidiReactor< ::grpc::testing::Request, ::grpc::testing::Response>* MethodA4() {
-      return new ::grpc::internal::UnimplementedBidiReactor<
+      return new ::grpc_impl::internal::UnimplementedBidiReactor<
         ::grpc::testing::Request, ::grpc::testing::Response>;}
   };
   typedef ExperimentalWithCallbackMethod_MethodA1<ExperimentalWithCallbackMethod_MethodA2<ExperimentalWithCallbackMethod_MethodA3<ExperimentalWithCallbackMethod_MethodA4<Service > > > > ExperimentalCallbackService;
@@ -582,7 +583,7 @@ class ServiceA final {
    public:
     ExperimentalWithRawCallbackMethod_MethodA1() {
       ::grpc::Service::experimental().MarkMethodRawCallback(0,
-        new ::grpc::internal::CallbackUnaryHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
+        new ::grpc_impl::internal::CallbackUnaryHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
           [this](::grpc::ServerContext* context,
                  const ::grpc::ByteBuffer* request,
                  ::grpc::ByteBuffer* response,
@@ -607,7 +608,7 @@ class ServiceA final {
    public:
     ExperimentalWithRawCallbackMethod_MethodA2() {
       ::grpc::Service::experimental().MarkMethodRawCallback(1,
-        new ::grpc::internal::CallbackClientStreamingHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
+        new ::grpc_impl::internal::CallbackClientStreamingHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
           [this] { return this->MethodA2(); }));
     }
     ~ExperimentalWithRawCallbackMethod_MethodA2() override {
@@ -619,7 +620,7 @@ class ServiceA final {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
     virtual ::grpc::experimental::ServerReadReactor< ::grpc::ByteBuffer, ::grpc::ByteBuffer>* MethodA2() {
-      return new ::grpc::internal::UnimplementedReadReactor<
+      return new ::grpc_impl::internal::UnimplementedReadReactor<
         ::grpc::ByteBuffer, ::grpc::ByteBuffer>;}
   };
   template <class BaseClass>
@@ -629,7 +630,7 @@ class ServiceA final {
    public:
     ExperimentalWithRawCallbackMethod_MethodA3() {
       ::grpc::Service::experimental().MarkMethodRawCallback(2,
-        new ::grpc::internal::CallbackServerStreamingHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
+        new ::grpc_impl::internal::CallbackServerStreamingHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
           [this] { return this->MethodA3(); }));
     }
     ~ExperimentalWithRawCallbackMethod_MethodA3() override {
@@ -641,7 +642,7 @@ class ServiceA final {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
     virtual ::grpc::experimental::ServerWriteReactor< ::grpc::ByteBuffer, ::grpc::ByteBuffer>* MethodA3() {
-      return new ::grpc::internal::UnimplementedWriteReactor<
+      return new ::grpc_impl::internal::UnimplementedWriteReactor<
         ::grpc::ByteBuffer, ::grpc::ByteBuffer>;}
   };
   template <class BaseClass>
@@ -651,7 +652,7 @@ class ServiceA final {
    public:
     ExperimentalWithRawCallbackMethod_MethodA4() {
       ::grpc::Service::experimental().MarkMethodRawCallback(3,
-        new ::grpc::internal::CallbackBidiHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
+        new ::grpc_impl::internal::CallbackBidiHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
           [this] { return this->MethodA4(); }));
     }
     ~ExperimentalWithRawCallbackMethod_MethodA4() override {
@@ -663,7 +664,7 @@ class ServiceA final {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
     virtual ::grpc::experimental::ServerBidiReactor< ::grpc::ByteBuffer, ::grpc::ByteBuffer>* MethodA4() {
-      return new ::grpc::internal::UnimplementedBidiReactor<
+      return new ::grpc_impl::internal::UnimplementedBidiReactor<
         ::grpc::ByteBuffer, ::grpc::ByteBuffer>;}
   };
   template <class BaseClass>
@@ -814,7 +815,7 @@ class ServiceB final {
    public:
     ExperimentalWithCallbackMethod_MethodB1() {
       ::grpc::Service::experimental().MarkMethodCallback(0,
-        new ::grpc::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
+        new ::grpc_impl::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>(
           [this](::grpc::ServerContext* context,
                  const ::grpc::testing::Request* request,
                  ::grpc::testing::Response* response,
@@ -824,7 +825,7 @@ class ServiceB final {
     }
     void SetMessageAllocatorFor_MethodB1(
         ::grpc::experimental::MessageAllocator< ::grpc::testing::Request, ::grpc::testing::Response>* allocator) {
-      static_cast<::grpc::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>*>(
+      static_cast<::grpc_impl::internal::CallbackUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>*>(
           ::grpc::Service::experimental().GetHandler(0))
               ->SetMessageAllocator(allocator);
     }
@@ -883,7 +884,7 @@ class ServiceB final {
    public:
     ExperimentalWithRawCallbackMethod_MethodB1() {
       ::grpc::Service::experimental().MarkMethodRawCallback(0,
-        new ::grpc::internal::CallbackUnaryHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
+        new ::grpc_impl::internal::CallbackUnaryHandler< ::grpc::ByteBuffer, ::grpc::ByteBuffer>(
           [this](::grpc::ServerContext* context,
                  const ::grpc::ByteBuffer* request,
                  ::grpc::ByteBuffer* response,

test/cpp/end2end/client_lb_end2end_test.cc

@@ -133,6 +133,59 @@ class MyTestServiceImpl : public TestServiceImpl {
   std::set<grpc::string> clients_;
 };
 
+class FakeResolverResponseGeneratorWrapper {
+ public:
+  FakeResolverResponseGeneratorWrapper()
+      : response_generator_(grpc_core::MakeRefCounted<
+                            grpc_core::FakeResolverResponseGenerator>()) {}
+
+  FakeResolverResponseGeneratorWrapper(
+      FakeResolverResponseGeneratorWrapper&& other) {
+    response_generator_ = std::move(other.response_generator_);
+  }
+
+  void SetNextResolution(const std::vector<int>& ports) {
+    grpc_core::ExecCtx exec_ctx;
+    response_generator_->SetResponse(BuildFakeResults(ports));
+  }
+
+  void SetNextResolutionUponError(const std::vector<int>& ports) {
+    grpc_core::ExecCtx exec_ctx;
+    response_generator_->SetReresolutionResponse(BuildFakeResults(ports));
+  }
+
+  void SetFailureOnReresolution() {
+    grpc_core::ExecCtx exec_ctx;
+    response_generator_->SetFailureOnReresolution();
+  }
+
+  grpc_core::FakeResolverResponseGenerator* Get() const {
+    return response_generator_.get();
+  }
+
+ private:
+  static grpc_core::Resolver::Result BuildFakeResults(
+      const std::vector<int>& ports) {
+    grpc_core::Resolver::Result result;
+    for (const int& port : ports) {
+      char* lb_uri_str;
+      gpr_asprintf(&lb_uri_str, "ipv4:127.0.0.1:%d", port);
+      grpc_uri* lb_uri = grpc_uri_parse(lb_uri_str, true);
+      GPR_ASSERT(lb_uri != nullptr);
+      grpc_resolved_address address;
+      GPR_ASSERT(grpc_parse_uri(lb_uri, &address));
+      result.addresses.emplace_back(address.addr, address.len,
+                                    nullptr /* args */);
+      grpc_uri_destroy(lb_uri);
+      gpr_free(lb_uri_str);
+    }
+    return result;
+  }
+
+  grpc_core::RefCountedPtr<grpc_core::FakeResolverResponseGenerator>
+      response_generator_;
+};
+
 class ClientLbEnd2endTest : public ::testing::Test {
  protected:
   ClientLbEnd2endTest()
@@ -147,11 +200,7 @@ class ClientLbEnd2endTest : public ::testing::Test {
     GPR_GLOBAL_CONFIG_SET(grpc_client_channel_backup_poll_interval_ms, 1);
   }
 
-  void SetUp() override {
-    grpc_init();
-    response_generator_ =
-        grpc_core::MakeRefCounted<grpc_core::FakeResolverResponseGenerator>();
-  }
+  void SetUp() override { grpc_init(); }
 
   void TearDown() override {
     for (size_t i = 0; i < servers_.size(); ++i) {
@@ -186,38 +235,6 @@ class ClientLbEnd2endTest : public ::testing::Test {
     }
   }
 
-  grpc_core::Resolver::Result BuildFakeResults(const std::vector<int>& ports) {
-    grpc_core::Resolver::Result result;
-    for (const int& port : ports) {
-      char* lb_uri_str;
-      gpr_asprintf(&lb_uri_str, "ipv4:127.0.0.1:%d", port);
-      grpc_uri* lb_uri = grpc_uri_parse(lb_uri_str, true);
-      GPR_ASSERT(lb_uri != nullptr);
-      grpc_resolved_address address;
-      GPR_ASSERT(grpc_parse_uri(lb_uri, &address));
-      result.addresses.emplace_back(address.addr, address.len,
-                                    nullptr /* args */);
-      grpc_uri_destroy(lb_uri);
-      gpr_free(lb_uri_str);
-    }
-    return result;
-  }
-
-  void SetNextResolution(const std::vector<int>& ports) {
-    grpc_core::ExecCtx exec_ctx;
-    response_generator_->SetResponse(BuildFakeResults(ports));
-  }
-
-  void SetNextResolutionUponError(const std::vector<int>& ports) {
-    grpc_core::ExecCtx exec_ctx;
-    response_generator_->SetReresolutionResponse(BuildFakeResults(ports));
-  }
-
-  void SetFailureOnReresolution() {
-    grpc_core::ExecCtx exec_ctx;
-    response_generator_->SetFailureOnReresolution();
-  }
-
   std::vector<int> GetServersPorts(size_t start_index = 0) {
     std::vector<int> ports;
     for (size_t i = start_index; i < servers_.size(); ++i) {
@@ -226,6 +243,10 @@ class ClientLbEnd2endTest : public ::testing::Test {
     return ports;
   }
 
+  FakeResolverResponseGeneratorWrapper BuildResolverResponseGenerator() {
+    return FakeResolverResponseGeneratorWrapper();
+  }
+
   std::unique_ptr<grpc::testing::EchoTestService::Stub> BuildStub(
       const std::shared_ptr<Channel>& channel) {
     return grpc::testing::EchoTestService::NewStub(channel);
@@ -233,12 +254,13 @@ class ClientLbEnd2endTest : public ::testing::Test {
 
   std::shared_ptr<Channel> BuildChannel(
       const grpc::string& lb_policy_name,
+      const FakeResolverResponseGeneratorWrapper& response_generator,
       ChannelArguments args = ChannelArguments()) {
     if (lb_policy_name.size() > 0) {
       args.SetLoadBalancingPolicyName(lb_policy_name);
     }  // else, default to pick first
     args.SetPointer(GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR,
-                    response_generator_.get());
+                    response_generator.Get());
     return ::grpc::CreateCustomChannel("fake:///", creds_, args);
   }
 
@@ -401,8 +423,6 @@ class ClientLbEnd2endTest : public ::testing::Test {
   const grpc::string server_host_;
   std::unique_ptr<grpc::testing::EchoTestService::Stub> stub_;
   std::vector<std::unique_ptr<ServerData>> servers_;
-  grpc_core::RefCountedPtr<grpc_core::FakeResolverResponseGenerator>
-      response_generator_;
   const grpc::string kRequestMessage_;
   std::shared_ptr<ChannelCredentials> creds_;
 };
@@ -410,7 +430,8 @@ class ClientLbEnd2endTest : public ::testing::Test {
 TEST_F(ClientLbEnd2endTest, ChannelStateConnectingWhenResolving) {
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("", response_generator);
   auto stub = BuildStub(channel);
   // Initial state should be IDLE.
   EXPECT_EQ(channel->GetState(false /* try_to_connect */), GRPC_CHANNEL_IDLE);
@@ -423,7 +444,7 @@ TEST_F(ClientLbEnd2endTest, ChannelStateConnectingWhenResolving) {
   EXPECT_EQ(channel->GetState(false /* try_to_connect */),
             GRPC_CHANNEL_CONNECTING);
   // Return a resolver result, which allows the connection attempt to proceed.
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   // We should eventually transition into state READY.
   EXPECT_TRUE(WaitForChannelReady(channel.get()));
 }
@@ -432,9 +453,11 @@ TEST_F(ClientLbEnd2endTest, PickFirst) {
   // Start servers and send one RPC per server.
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("");  // test that pick first is the default.
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel(
+      "", response_generator);  // test that pick first is the default.
   auto stub = BuildStub(channel);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   for (size_t i = 0; i < servers_.size(); ++i) {
     CheckRpcSendOk(stub, DEBUG_LOCATION);
   }
@@ -454,19 +477,22 @@ TEST_F(ClientLbEnd2endTest, PickFirst) {
 }
 
 TEST_F(ClientLbEnd2endTest, PickFirstProcessPending) {
-  StartServers(1);                  // Single server
-  auto channel = BuildChannel("");  // test that pick first is the default.
+  StartServers(1);  // Single server
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel(
+      "", response_generator);  // test that pick first is the default.
   auto stub = BuildStub(channel);
-  SetNextResolution({servers_[0]->port_});
+  response_generator.SetNextResolution({servers_[0]->port_});
   WaitForServer(stub, 0, DEBUG_LOCATION);
   // Create a new channel and its corresponding PF LB policy, which will pick
   // the subchannels in READY state from the previous RPC against the same
   // target (even if it happened over a different channel, because subchannels
   // are globally reused). Progress should happen without any transition from
   // this READY state.
-  auto second_channel = BuildChannel("");
+  auto second_response_generator = BuildResolverResponseGenerator();
+  auto second_channel = BuildChannel("", second_response_generator);
   auto second_stub = BuildStub(second_channel);
-  SetNextResolution({servers_[0]->port_});
+  second_response_generator.SetNextResolution({servers_[0]->port_});
   CheckRpcSendOk(second_stub, DEBUG_LOCATION);
 }
 
@@ -479,16 +505,18 @@ TEST_F(ClientLbEnd2endTest, PickFirstSelectsReadyAtStartup) {
                             grpc_pick_unused_port_or_die()};
   CreateServers(2, ports);
   StartServer(1);
-  auto channel1 = BuildChannel("pick_first", args);
+  auto response_generator1 = BuildResolverResponseGenerator();
+  auto channel1 = BuildChannel("pick_first", response_generator1, args);
   auto stub1 = BuildStub(channel1);
-  SetNextResolution(ports);
+  response_generator1.SetNextResolution(ports);
   // Wait for second server to be ready.
   WaitForServer(stub1, 1, DEBUG_LOCATION);
   // Create a second channel with the same addresses.  Its PF instance
   // should immediately pick the second subchannel, since it's already
   // in READY state.
-  auto channel2 = BuildChannel("pick_first", args);
-  SetNextResolution(ports);
+  auto response_generator2 = BuildResolverResponseGenerator();
+  auto channel2 = BuildChannel("pick_first", response_generator2, args);
+  response_generator2.SetNextResolution(ports);
   // Check that the channel reports READY without waiting for the
   // initial backoff.
   EXPECT_TRUE(WaitForChannelReady(channel2.get(), 1 /* timeout_seconds */));
@@ -500,9 +528,10 @@ TEST_F(ClientLbEnd2endTest, PickFirstBackOffInitialReconnect) {
   args.SetInt(GRPC_ARG_INITIAL_RECONNECT_BACKOFF_MS, kInitialBackOffMs);
   const std::vector<int> ports = {grpc_pick_unused_port_or_die()};
   const gpr_timespec t0 = gpr_now(GPR_CLOCK_MONOTONIC);
-  auto channel = BuildChannel("pick_first", args);
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator, args);
   auto stub = BuildStub(channel);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   // The channel won't become connected (there's no server).
   ASSERT_FALSE(channel->WaitForConnected(
       grpc_timeout_milliseconds_to_deadline(kInitialBackOffMs * 2)));
@@ -529,9 +558,10 @@ TEST_F(ClientLbEnd2endTest, PickFirstBackOffMinReconnect) {
   constexpr int kMinReconnectBackOffMs = 1000;
   args.SetInt(GRPC_ARG_MIN_RECONNECT_BACKOFF_MS, kMinReconnectBackOffMs);
   const std::vector<int> ports = {grpc_pick_unused_port_or_die()};
-  auto channel = BuildChannel("pick_first", args);
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator, args);
   auto stub = BuildStub(channel);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   // Make connection delay a 10% longer than it's willing to in order to make
   // sure we are hitting the codepath that waits for the min reconnect backoff.
   gpr_atm_rel_store(&g_connection_delay_ms, kMinReconnectBackOffMs * 1.10);
@@ -554,9 +584,10 @@ TEST_F(ClientLbEnd2endTest, PickFirstResetConnectionBackoff) {
   constexpr int kInitialBackOffMs = 1000;
   args.SetInt(GRPC_ARG_INITIAL_RECONNECT_BACKOFF_MS, kInitialBackOffMs);
   const std::vector<int> ports = {grpc_pick_unused_port_or_die()};
-  auto channel = BuildChannel("pick_first", args);
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator, args);
   auto stub = BuildStub(channel);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   // The channel won't become connected (there's no server).
   EXPECT_FALSE(
       channel->WaitForConnected(grpc_timeout_milliseconds_to_deadline(10)));
@@ -585,9 +616,10 @@ TEST_F(ClientLbEnd2endTest,
   constexpr int kInitialBackOffMs = 1000;
   args.SetInt(GRPC_ARG_INITIAL_RECONNECT_BACKOFF_MS, kInitialBackOffMs);
   const std::vector<int> ports = {grpc_pick_unused_port_or_die()};
-  auto channel = BuildChannel("pick_first", args);
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator, args);
   auto stub = BuildStub(channel);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   // Wait for connect, which should fail ~immediately, because the server
   // is not up.
   gpr_log(GPR_INFO, "=== INITIAL CONNECTION ATTEMPT");
@@ -628,21 +660,22 @@ TEST_F(ClientLbEnd2endTest, PickFirstUpdates) {
   // Start servers and send one RPC per server.
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("pick_first");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator);
   auto stub = BuildStub(channel);
 
   std::vector<int> ports;
 
   // Perform one RPC against the first server.
   ports.emplace_back(servers_[0]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** SET [0] *******");
   CheckRpcSendOk(stub, DEBUG_LOCATION);
   EXPECT_EQ(servers_[0]->service_.request_count(), 1);
 
   // An empty update will result in the channel going into TRANSIENT_FAILURE.
   ports.clear();
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** SET none *******");
   grpc_connectivity_state channel_state;
   do {
@@ -654,7 +687,7 @@ TEST_F(ClientLbEnd2endTest, PickFirstUpdates) {
   // Next update introduces servers_[1], making the channel recover.
   ports.clear();
   ports.emplace_back(servers_[1]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** SET [1] *******");
   WaitForServer(stub, 1, DEBUG_LOCATION);
   EXPECT_EQ(servers_[0]->service_.request_count(), 0);
@@ -662,7 +695,7 @@ TEST_F(ClientLbEnd2endTest, PickFirstUpdates) {
   // And again for servers_[2]
   ports.clear();
   ports.emplace_back(servers_[2]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** SET [2] *******");
   WaitForServer(stub, 2, DEBUG_LOCATION);
   EXPECT_EQ(servers_[0]->service_.request_count(), 0);
@@ -676,14 +709,15 @@ TEST_F(ClientLbEnd2endTest, PickFirstUpdateSuperset) {
   // Start servers and send one RPC per server.
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("pick_first");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator);
   auto stub = BuildStub(channel);
 
   std::vector<int> ports;
 
   // Perform one RPC against the first server.
   ports.emplace_back(servers_[0]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** SET [0] *******");
   CheckRpcSendOk(stub, DEBUG_LOCATION);
   EXPECT_EQ(servers_[0]->service_.request_count(), 1);
@@ -693,7 +727,7 @@ TEST_F(ClientLbEnd2endTest, PickFirstUpdateSuperset) {
   ports.clear();
   ports.emplace_back(servers_[1]->port_);
   ports.emplace_back(servers_[0]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** SET superset *******");
   CheckRpcSendOk(stub, DEBUG_LOCATION);
   // We stick to the previously connected server.
@@ -710,12 +744,14 @@ TEST_F(ClientLbEnd2endTest, PickFirstGlobalSubchannelPool) {
   StartServers(kNumServers);
   std::vector<int> ports = GetServersPorts();
   // Create two channels that (by default) use the global subchannel pool.
-  auto channel1 = BuildChannel("pick_first");
+  auto response_generator1 = BuildResolverResponseGenerator();
+  auto channel1 = BuildChannel("pick_first", response_generator1);
   auto stub1 = BuildStub(channel1);
-  SetNextResolution(ports);
-  auto channel2 = BuildChannel("pick_first");
+  response_generator1.SetNextResolution(ports);
+  auto response_generator2 = BuildResolverResponseGenerator();
+  auto channel2 = BuildChannel("pick_first", response_generator2);
   auto stub2 = BuildStub(channel2);
-  SetNextResolution(ports);
+  response_generator2.SetNextResolution(ports);
   WaitForServer(stub1, 0, DEBUG_LOCATION);
   // Send one RPC on each channel.
   CheckRpcSendOk(stub1, DEBUG_LOCATION);
@@ -735,12 +771,14 @@ TEST_F(ClientLbEnd2endTest, PickFirstLocalSubchannelPool) {
   // Create two channels that use local subchannel pool.
   ChannelArguments args;
   args.SetInt(GRPC_ARG_USE_LOCAL_SUBCHANNEL_POOL, 1);
-  auto channel1 = BuildChannel("pick_first", args);
+  auto response_generator1 = BuildResolverResponseGenerator();
+  auto channel1 = BuildChannel("pick_first", response_generator1, args);
   auto stub1 = BuildStub(channel1);
-  SetNextResolution(ports);
-  auto channel2 = BuildChannel("pick_first", args);
+  response_generator1.SetNextResolution(ports);
+  auto response_generator2 = BuildResolverResponseGenerator();
+  auto channel2 = BuildChannel("pick_first", response_generator2, args);
   auto stub2 = BuildStub(channel2);
-  SetNextResolution(ports);
+  response_generator2.SetNextResolution(ports);
   WaitForServer(stub1, 0, DEBUG_LOCATION);
   // Send one RPC on each channel.
   CheckRpcSendOk(stub1, DEBUG_LOCATION);
@@ -756,13 +794,14 @@ TEST_F(ClientLbEnd2endTest, PickFirstManyUpdates) {
   const int kNumUpdates = 1000;
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("pick_first");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator);
   auto stub = BuildStub(channel);
   std::vector<int> ports = GetServersPorts();
   for (size_t i = 0; i < kNumUpdates; ++i) {
     std::shuffle(ports.begin(), ports.end(),
                  std::mt19937(std::random_device()()));
-    SetNextResolution(ports);
+    response_generator.SetNextResolution(ports);
     // We should re-enter core at the end of the loop to give the resolution
     // setting closure a chance to run.
     if ((i + 1) % 10 == 0) CheckRpcSendOk(stub, DEBUG_LOCATION);
@@ -784,16 +823,17 @@ TEST_F(ClientLbEnd2endTest, PickFirstReresolutionNoSelected) {
       dead_ports.emplace_back(grpc_pick_unused_port_or_die());
     }
   }
-  auto channel = BuildChannel("pick_first");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator);
   auto stub = BuildStub(channel);
   // The initial resolution only contains dead ports. There won't be any
   // selected subchannel. Re-resolution will return the same result.
-  SetNextResolution(dead_ports);
+  response_generator.SetNextResolution(dead_ports);
   gpr_log(GPR_INFO, "****** INITIAL RESOLUTION SET *******");
   for (size_t i = 0; i < 10; ++i) CheckRpcSendFailure(stub);
   // Set a re-resolution result that contains reachable ports, so that the
   // pick_first LB policy can recover soon.
-  SetNextResolutionUponError(alive_ports);
+  response_generator.SetNextResolutionUponError(alive_ports);
   gpr_log(GPR_INFO, "****** RE-RESOLUTION SET *******");
   WaitForServer(stub, 0, DEBUG_LOCATION, true /* ignore_failure */);
   CheckRpcSendOk(stub, DEBUG_LOCATION);
@@ -805,9 +845,10 @@ TEST_F(ClientLbEnd2endTest, PickFirstReresolutionNoSelected) {
 TEST_F(ClientLbEnd2endTest, PickFirstReconnectWithoutNewResolverResult) {
   std::vector<int> ports = {grpc_pick_unused_port_or_die()};
   StartServers(1, ports);
-  auto channel = BuildChannel("pick_first");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator);
   auto stub = BuildStub(channel);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** INITIAL CONNECTION *******");
   WaitForServer(stub, 0, DEBUG_LOCATION);
   gpr_log(GPR_INFO, "****** STOPPING SERVER ******");
@@ -824,9 +865,10 @@ TEST_F(ClientLbEnd2endTest,
                             grpc_pick_unused_port_or_die()};
   CreateServers(2, ports);
   StartServer(1);
-  auto channel = BuildChannel("pick_first");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("pick_first", response_generator);
   auto stub = BuildStub(channel);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** INITIAL CONNECTION *******");
   WaitForServer(stub, 1, DEBUG_LOCATION);
   gpr_log(GPR_INFO, "****** STOPPING SERVER ******");
@@ -840,9 +882,10 @@ TEST_F(ClientLbEnd2endTest,
 TEST_F(ClientLbEnd2endTest, PickFirstCheckStateBeforeStartWatch) {
   std::vector<int> ports = {grpc_pick_unused_port_or_die()};
   StartServers(1, ports);
-  auto channel_1 = BuildChannel("pick_first");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel_1 = BuildChannel("pick_first", response_generator);
   auto stub_1 = BuildStub(channel_1);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** RESOLUTION SET FOR CHANNEL 1 *******");
   WaitForServer(stub_1, 0, DEBUG_LOCATION);
   gpr_log(GPR_INFO, "****** CHANNEL 1 CONNECTED *******");
@@ -851,13 +894,10 @@ TEST_F(ClientLbEnd2endTest, PickFirstCheckStateBeforeStartWatch) {
   // create a new subchannel and hold a ref to it.
   StartServers(1, ports);
   gpr_log(GPR_INFO, "****** SERVER RESTARTED *******");
-  auto channel_2 = BuildChannel("pick_first");
+  auto response_generator_2 = BuildResolverResponseGenerator();
+  auto channel_2 = BuildChannel("pick_first", response_generator_2);
   auto stub_2 = BuildStub(channel_2);
-  // TODO(juanlishen): This resolution result will only be visible to channel 2
-  // since the response generator is only associated with channel 2 now. We
-  // should change the response generator to be able to deliver updates to
-  // multiple channels at once.
-  SetNextResolution(ports);
+  response_generator_2.SetNextResolution(ports);
   gpr_log(GPR_INFO, "****** RESOLUTION SET FOR CHANNEL 2 *******");
   WaitForServer(stub_2, 0, DEBUG_LOCATION, true);
   gpr_log(GPR_INFO, "****** CHANNEL 2 CONNECTED *******");
@@ -883,13 +923,15 @@ TEST_F(ClientLbEnd2endTest, PickFirstIdleOnDisconnect) {
   // Start server, send RPC, and make sure channel is READY.
   const int kNumServers = 1;
   StartServers(kNumServers);
-  auto channel = BuildChannel("");  // pick_first is the default.
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel =
+      BuildChannel("", response_generator);  // pick_first is the default.
   auto stub = BuildStub(channel);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   CheckRpcSendOk(stub, DEBUG_LOCATION);
   EXPECT_EQ(channel->GetState(false), GRPC_CHANNEL_READY);
   // Stop server.  Channel should go into state IDLE.
-  SetFailureOnReresolution();
+  response_generator.SetFailureOnReresolution();
   servers_[0]->Shutdown();
   EXPECT_TRUE(WaitForChannelNotReady(channel.get()));
   EXPECT_EQ(channel->GetState(false), GRPC_CHANNEL_IDLE);
@@ -897,14 +939,16 @@ TEST_F(ClientLbEnd2endTest, PickFirstIdleOnDisconnect) {
 }
 
 TEST_F(ClientLbEnd2endTest, PickFirstPendingUpdateAndSelectedSubchannelFails) {
-  auto channel = BuildChannel("");  // pick_first is the default.
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel =
+      BuildChannel("", response_generator);  // pick_first is the default.
   auto stub = BuildStub(channel);
   // Create a number of servers, but only start 1 of them.
   CreateServers(10);
   StartServer(0);
   // Initially resolve to first server and make sure it connects.
   gpr_log(GPR_INFO, "Phase 1: Connect to first server.");
-  SetNextResolution({servers_[0]->port_});
+  response_generator.SetNextResolution({servers_[0]->port_});
   CheckRpcSendOk(stub, DEBUG_LOCATION, true /* wait_for_ready */);
   EXPECT_EQ(channel->GetState(false), GRPC_CHANNEL_READY);
   // Send a resolution update with the remaining servers, none of which are
@@ -916,7 +960,7 @@ TEST_F(ClientLbEnd2endTest, PickFirstPendingUpdateAndSelectedSubchannelFails) {
   gpr_log(GPR_INFO,
           "Phase 2: Resolver update pointing to remaining "
           "(not started) servers.");
-  SetNextResolution(GetServersPorts(1 /* start_index */));
+  response_generator.SetNextResolution(GetServersPorts(1 /* start_index */));
   // RPCs will continue to be sent to the first server.
   CheckRpcSendOk(stub, DEBUG_LOCATION);
   // Now stop the first server, so that the current subchannel list
@@ -947,9 +991,11 @@ TEST_F(ClientLbEnd2endTest, PickFirstStaysIdleUponEmptyUpdate) {
   // Start server, send RPC, and make sure channel is READY.
   const int kNumServers = 1;
   StartServers(kNumServers);
-  auto channel = BuildChannel("");  // pick_first is the default.
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel =
+      BuildChannel("", response_generator);  // pick_first is the default.
   auto stub = BuildStub(channel);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   CheckRpcSendOk(stub, DEBUG_LOCATION);
   EXPECT_EQ(channel->GetState(false), GRPC_CHANNEL_READY);
   // Stop server.  Channel should go into state IDLE.
@@ -958,13 +1004,13 @@ TEST_F(ClientLbEnd2endTest, PickFirstStaysIdleUponEmptyUpdate) {
   EXPECT_EQ(channel->GetState(false), GRPC_CHANNEL_IDLE);
   // Now send resolver update that includes no addresses.  Channel
   // should stay in state IDLE.
-  SetNextResolution({});
+  response_generator.SetNextResolution({});
   EXPECT_FALSE(channel->WaitForStateChange(
       GRPC_CHANNEL_IDLE, grpc_timeout_seconds_to_deadline(3)));
   // Now bring the backend back up and send a non-empty resolver update,
   // and then try to send an RPC.  Channel should go back into state READY.
   StartServer(0);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   CheckRpcSendOk(stub, DEBUG_LOCATION);
   EXPECT_EQ(channel->GetState(false), GRPC_CHANNEL_READY);
 }
@@ -973,9 +1019,10 @@ TEST_F(ClientLbEnd2endTest, RoundRobin) {
   // Start servers and send one RPC per server.
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("round_robin");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator);
   auto stub = BuildStub(channel);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   // Wait until all backends are ready.
   do {
     CheckRpcSendOk(stub, DEBUG_LOCATION);
@@ -999,18 +1046,20 @@ TEST_F(ClientLbEnd2endTest, RoundRobin) {
 
 TEST_F(ClientLbEnd2endTest, RoundRobinProcessPending) {
   StartServers(1);  // Single server
-  auto channel = BuildChannel("round_robin");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator);
   auto stub = BuildStub(channel);
-  SetNextResolution({servers_[0]->port_});
+  response_generator.SetNextResolution({servers_[0]->port_});
   WaitForServer(stub, 0, DEBUG_LOCATION);
   // Create a new channel and its corresponding RR LB policy, which will pick
   // the subchannels in READY state from the previous RPC against the same
   // target (even if it happened over a different channel, because subchannels
   // are globally reused). Progress should happen without any transition from
   // this READY state.
-  auto second_channel = BuildChannel("round_robin");
+  auto second_response_generator = BuildResolverResponseGenerator();
+  auto second_channel = BuildChannel("round_robin", second_response_generator);
   auto second_stub = BuildStub(second_channel);
-  SetNextResolution({servers_[0]->port_});
+  second_response_generator.SetNextResolution({servers_[0]->port_});
   CheckRpcSendOk(second_stub, DEBUG_LOCATION);
 }
 
@@ -1018,13 +1067,14 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdates) {
   // Start servers and send one RPC per server.
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("round_robin");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator);
   auto stub = BuildStub(channel);
   std::vector<int> ports;
   // Start with a single server.
   gpr_log(GPR_INFO, "*** FIRST BACKEND ***");
   ports.emplace_back(servers_[0]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   WaitForServer(stub, 0, DEBUG_LOCATION);
   // Send RPCs. They should all go servers_[0]
   for (size_t i = 0; i < 10; ++i) CheckRpcSendOk(stub, DEBUG_LOCATION);
@@ -1036,7 +1086,7 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdates) {
   gpr_log(GPR_INFO, "*** SECOND BACKEND ***");
   ports.clear();
   ports.emplace_back(servers_[1]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   // Wait until update has been processed, as signaled by the second backend
   // receiving a request.
   EXPECT_EQ(0, servers_[1]->service_.request_count());
@@ -1050,7 +1100,7 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdates) {
   gpr_log(GPR_INFO, "*** THIRD BACKEND ***");
   ports.clear();
   ports.emplace_back(servers_[2]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   WaitForServer(stub, 2, DEBUG_LOCATION);
   for (size_t i = 0; i < 10; ++i) CheckRpcSendOk(stub, DEBUG_LOCATION);
   EXPECT_EQ(0, servers_[0]->service_.request_count());
@@ -1063,7 +1113,7 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdates) {
   ports.emplace_back(servers_[0]->port_);
   ports.emplace_back(servers_[1]->port_);
   ports.emplace_back(servers_[2]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   WaitForServer(stub, 0, DEBUG_LOCATION);
   WaitForServer(stub, 1, DEBUG_LOCATION);
   WaitForServer(stub, 2, DEBUG_LOCATION);
@@ -1075,7 +1125,7 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdates) {
   // An empty update will result in the channel going into TRANSIENT_FAILURE.
   gpr_log(GPR_INFO, "*** NO BACKENDS ***");
   ports.clear();
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   grpc_connectivity_state channel_state;
   do {
     channel_state = channel->GetState(true /* try to connect */);
@@ -1086,7 +1136,7 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdates) {
   gpr_log(GPR_INFO, "*** BACK TO SECOND BACKEND ***");
   ports.clear();
   ports.emplace_back(servers_[1]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   WaitForServer(stub, 1, DEBUG_LOCATION);
   channel_state = channel->GetState(false /* try to connect */);
   ASSERT_EQ(channel_state, GRPC_CHANNEL_READY);
@@ -1097,13 +1147,14 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdates) {
 TEST_F(ClientLbEnd2endTest, RoundRobinUpdateInError) {
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("round_robin");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator);
   auto stub = BuildStub(channel);
   std::vector<int> ports;
 
   // Start with a single server.
   ports.emplace_back(servers_[0]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   WaitForServer(stub, 0, DEBUG_LOCATION);
   // Send RPCs. They should all go to servers_[0]
   for (size_t i = 0; i < 10; ++i) SendRpc(stub);
@@ -1116,7 +1167,7 @@ TEST_F(ClientLbEnd2endTest, RoundRobinUpdateInError) {
   servers_[1]->Shutdown();
   ports.emplace_back(servers_[1]->port_);
   ports.emplace_back(servers_[2]->port_);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   WaitForServer(stub, 0, DEBUG_LOCATION);
   WaitForServer(stub, 2, DEBUG_LOCATION);
 
@@ -1130,13 +1181,14 @@ TEST_F(ClientLbEnd2endTest, RoundRobinManyUpdates) {
   // Start servers and send one RPC per server.
   const int kNumServers = 3;
   StartServers(kNumServers);
-  auto channel = BuildChannel("round_robin");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator);
   auto stub = BuildStub(channel);
   std::vector<int> ports = GetServersPorts();
   for (size_t i = 0; i < 1000; ++i) {
     std::shuffle(ports.begin(), ports.end(),
                  std::mt19937(std::random_device()()));
-    SetNextResolution(ports);
+    response_generator.SetNextResolution(ports);
     if (i % 10 == 0) CheckRpcSendOk(stub, DEBUG_LOCATION);
   }
   // Check LB policy name for the channel.
@@ -1162,9 +1214,10 @@ TEST_F(ClientLbEnd2endTest, RoundRobinReresolve) {
     second_ports.push_back(grpc_pick_unused_port_or_die());
   }
   StartServers(kNumServers, first_ports);
-  auto channel = BuildChannel("round_robin");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator);
   auto stub = BuildStub(channel);
-  SetNextResolution(first_ports);
+  response_generator.SetNextResolution(first_ports);
   // Send a number of RPCs, which succeed.
   for (size_t i = 0; i < 100; ++i) {
     CheckRpcSendOk(stub, DEBUG_LOCATION);
@@ -1188,7 +1241,7 @@ TEST_F(ClientLbEnd2endTest, RoundRobinReresolve) {
   StartServers(kNumServers, second_ports);
   // Don't notify of the update. Wait for the LB policy's re-resolution to
   // "pull" the new ports.
-  SetNextResolutionUponError(second_ports);
+  response_generator.SetNextResolutionUponError(second_ports);
   gpr_log(GPR_INFO, "****** SERVERS RESTARTED *******");
   gpr_log(GPR_INFO, "****** SENDING REQUEST TO SUCCEED *******");
   // Client request should eventually (but still fairly soon) succeed.
@@ -1205,9 +1258,10 @@ TEST_F(ClientLbEnd2endTest, RoundRobinSingleReconnect) {
   const int kNumServers = 3;
   StartServers(kNumServers);
   const auto ports = GetServersPorts();
-  auto channel = BuildChannel("round_robin");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator);
   auto stub = BuildStub(channel);
-  SetNextResolution(ports);
+  response_generator.SetNextResolution(ports);
   for (size_t i = 0; i < kNumServers; ++i) {
     WaitForServer(stub, i, DEBUG_LOCATION);
   }
@@ -1251,9 +1305,10 @@ TEST_F(ClientLbEnd2endTest,
   args.SetServiceConfigJSON(
       "{\"healthCheckConfig\": "
       "{\"serviceName\": \"health_check_service_name\"}}");
-  auto channel = BuildChannel("round_robin", args);
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator, args);
   auto stub = BuildStub(channel);
-  SetNextResolution({servers_[0]->port_});
+  response_generator.SetNextResolution({servers_[0]->port_});
   EXPECT_TRUE(WaitForChannelReady(channel.get()));
   CheckRpcSendOk(stub, DEBUG_LOCATION);
 }
@@ -1267,9 +1322,10 @@ TEST_F(ClientLbEnd2endTest, RoundRobinWithHealthChecking) {
   args.SetServiceConfigJSON(
       "{\"healthCheckConfig\": "
       "{\"serviceName\": \"health_check_service_name\"}}");
-  auto channel = BuildChannel("round_robin", args);
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel = BuildChannel("round_robin", response_generator, args);
   auto stub = BuildStub(channel);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   // Channel should not become READY, because health checks should be failing.
   gpr_log(GPR_INFO,
           "*** initial state: unknown health check service name for "
@@ -1341,15 +1397,17 @@ TEST_F(ClientLbEnd2endTest, RoundRobinWithHealthCheckingInhibitPerChannel) {
   args.SetServiceConfigJSON(
       "{\"healthCheckConfig\": "
       "{\"serviceName\": \"health_check_service_name\"}}");
-  auto channel1 = BuildChannel("round_robin", args);
+  auto response_generator1 = BuildResolverResponseGenerator();
+  auto channel1 = BuildChannel("round_robin", response_generator1, args);
   auto stub1 = BuildStub(channel1);
   std::vector<int> ports = GetServersPorts();
-  SetNextResolution(ports);
+  response_generator1.SetNextResolution(ports);
   // Create a channel with health checking enabled but inhibited.
   args.SetInt(GRPC_ARG_INHIBIT_HEALTH_CHECKING, 1);
-  auto channel2 = BuildChannel("round_robin", args);
+  auto response_generator2 = BuildResolverResponseGenerator();
+  auto channel2 = BuildChannel("round_robin", response_generator2, args);
   auto stub2 = BuildStub(channel2);
-  SetNextResolution(ports);
+  response_generator2.SetNextResolution(ports);
   // First channel should not become READY, because health checks should be
   // failing.
   EXPECT_FALSE(WaitForChannelReady(channel1.get(), 1));
@@ -1376,19 +1434,21 @@ TEST_F(ClientLbEnd2endTest, RoundRobinWithHealthCheckingServiceNamePerChannel) {
   args.SetServiceConfigJSON(
       "{\"healthCheckConfig\": "
       "{\"serviceName\": \"health_check_service_name\"}}");
-  auto channel1 = BuildChannel("round_robin", args);
+  auto response_generator1 = BuildResolverResponseGenerator();
+  auto channel1 = BuildChannel("round_robin", response_generator1, args);
   auto stub1 = BuildStub(channel1);
   std::vector<int> ports = GetServersPorts();
-  SetNextResolution(ports);
+  response_generator1.SetNextResolution(ports);
   // Create a channel with health-checking enabled with a different
   // service name.
   ChannelArguments args2;
   args2.SetServiceConfigJSON(
       "{\"healthCheckConfig\": "
       "{\"serviceName\": \"health_check_service_name2\"}}");
-  auto channel2 = BuildChannel("round_robin", args2);
+  auto response_generator2 = BuildResolverResponseGenerator();
+  auto channel2 = BuildChannel("round_robin", response_generator2, args2);
   auto stub2 = BuildStub(channel2);
-  SetNextResolution(ports);
+  response_generator2.SetNextResolution(ports);
   // Allow health checks from channel 2 to succeed.
   servers_[0]->SetServingStatus("health_check_service_name2", true);
   // First channel should not become READY, because health checks should be
@@ -1438,9 +1498,11 @@ TEST_F(ClientLbInterceptTrailingMetadataTest, InterceptsRetriesDisabled) {
   const int kNumServers = 1;
   const int kNumRpcs = 10;
   StartServers(kNumServers);
-  auto channel = BuildChannel("intercept_trailing_metadata_lb");
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel =
+      BuildChannel("intercept_trailing_metadata_lb", response_generator);
   auto stub = BuildStub(channel);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   for (size_t i = 0; i < kNumRpcs; ++i) {
     CheckRpcSendOk(stub, DEBUG_LOCATION);
   }
@@ -1470,9 +1532,11 @@ TEST_F(ClientLbInterceptTrailingMetadataTest, InterceptsRetriesEnabled) {
       "    }\n"
       "  } ]\n"
       "}");
-  auto channel = BuildChannel("intercept_trailing_metadata_lb", args);
+  auto response_generator = BuildResolverResponseGenerator();
+  auto channel =
+      BuildChannel("intercept_trailing_metadata_lb", response_generator, args);
   auto stub = BuildStub(channel);
-  SetNextResolution(GetServersPorts());
+  response_generator.SetNextResolution(GetServersPorts());
   for (size_t i = 0; i < kNumRpcs; ++i) {
     CheckRpcSendOk(stub, DEBUG_LOCATION);
   }

tools/distrib/python/bazel_deps.sh

@@ -26,6 +26,7 @@ else
   docker build -t bazel_local_img tools/dockerfile/test/sanity
   docker run -v "$(realpath .):/src/grpc/:ro" \
     -w /src/grpc/third_party/protobuf         \
+    --rm=true                                 \
     bazel_local_img                           \
     bazel query 'deps('$1')'
 fi

tools/doxygen/Doxyfile.c++

@@ -947,7 +947,9 @@ include/grpcpp/impl/channel_argument_option.h \
 include/grpcpp/impl/client_unary_call.h \
 include/grpcpp/impl/codegen/async_generic_service.h \
 include/grpcpp/impl/codegen/async_stream.h \
+include/grpcpp/impl/codegen/async_stream_impl.h \
 include/grpcpp/impl/codegen/async_unary_call.h \
+include/grpcpp/impl/codegen/async_unary_call_impl.h \
 include/grpcpp/impl/codegen/byte_buffer.h \
 include/grpcpp/impl/codegen/call.h \
 include/grpcpp/impl/codegen/call_hook.h \
@@ -956,6 +958,7 @@ include/grpcpp/impl/codegen/call_op_set_interface.h \
 include/grpcpp/impl/codegen/callback_common.h \
 include/grpcpp/impl/codegen/channel_interface.h \
 include/grpcpp/impl/codegen/client_callback.h \
+include/grpcpp/impl/codegen/client_callback_impl.h \
 include/grpcpp/impl/codegen/client_context.h \
 include/grpcpp/impl/codegen/client_context_impl.h \
 include/grpcpp/impl/codegen/client_interceptor.h \
@@ -983,6 +986,7 @@ include/grpcpp/impl/codegen/rpc_service_method.h \
 include/grpcpp/impl/codegen/security/auth_context.h \
 include/grpcpp/impl/codegen/serialization_traits.h \
 include/grpcpp/impl/codegen/server_callback.h \
+include/grpcpp/impl/codegen/server_callback_impl.h \
 include/grpcpp/impl/codegen/server_context.h \
 include/grpcpp/impl/codegen/server_context_impl.h \
 include/grpcpp/impl/codegen/server_interceptor.h \
@@ -995,6 +999,7 @@ include/grpcpp/impl/codegen/string_ref.h \
 include/grpcpp/impl/codegen/stub_options.h \
 include/grpcpp/impl/codegen/sync.h \
 include/grpcpp/impl/codegen/sync_stream.h \
+include/grpcpp/impl/codegen/sync_stream_impl.h \
 include/grpcpp/impl/codegen/time.h \
 include/grpcpp/impl/grpc_library.h \
 include/grpcpp/impl/method_handler_impl.h \
@@ -1024,11 +1029,14 @@ include/grpcpp/server_impl.h \
 include/grpcpp/server_posix.h \
 include/grpcpp/server_posix_impl.h \
 include/grpcpp/support/async_stream.h \
+include/grpcpp/support/async_stream_impl.h \
 include/grpcpp/support/async_unary_call.h \
+include/grpcpp/support/async_unary_call_impl.h \
 include/grpcpp/support/byte_buffer.h \
 include/grpcpp/support/channel_arguments.h \
 include/grpcpp/support/channel_arguments_impl.h \
 include/grpcpp/support/client_callback.h \
+include/grpcpp/support/client_callback_impl.h \
 include/grpcpp/support/client_interceptor.h \
 include/grpcpp/support/config.h \
 include/grpcpp/support/interceptor.h \
@@ -1036,6 +1044,7 @@ include/grpcpp/support/message_allocator.h \
 include/grpcpp/support/proto_buffer_reader.h \
 include/grpcpp/support/proto_buffer_writer.h \
 include/grpcpp/support/server_callback.h \
+include/grpcpp/support/server_callback_impl.h \
 include/grpcpp/support/server_interceptor.h \
 include/grpcpp/support/slice.h \
 include/grpcpp/support/status.h \
@@ -1043,6 +1052,7 @@ include/grpcpp/support/status_code_enum.h \
 include/grpcpp/support/string_ref.h \
 include/grpcpp/support/stub_options.h \
 include/grpcpp/support/sync_stream.h \
+include/grpcpp/support/sync_stream_impl.h \
 include/grpcpp/support/time.h \
 include/grpcpp/support/validate_service_config.h
 

tools/doxygen/Doxyfile.c++.internal

@@ -948,7 +948,9 @@ include/grpcpp/impl/channel_argument_option.h \
 include/grpcpp/impl/client_unary_call.h \
 include/grpcpp/impl/codegen/async_generic_service.h \
 include/grpcpp/impl/codegen/async_stream.h \
+include/grpcpp/impl/codegen/async_stream_impl.h \
 include/grpcpp/impl/codegen/async_unary_call.h \
+include/grpcpp/impl/codegen/async_unary_call_impl.h \
 include/grpcpp/impl/codegen/byte_buffer.h \
 include/grpcpp/impl/codegen/call.h \
 include/grpcpp/impl/codegen/call_hook.h \
@@ -957,6 +959,7 @@ include/grpcpp/impl/codegen/call_op_set_interface.h \
 include/grpcpp/impl/codegen/callback_common.h \
 include/grpcpp/impl/codegen/channel_interface.h \
 include/grpcpp/impl/codegen/client_callback.h \
+include/grpcpp/impl/codegen/client_callback_impl.h \
 include/grpcpp/impl/codegen/client_context.h \
 include/grpcpp/impl/codegen/client_context_impl.h \
 include/grpcpp/impl/codegen/client_interceptor.h \
@@ -985,6 +988,7 @@ include/grpcpp/impl/codegen/rpc_service_method.h \
 include/grpcpp/impl/codegen/security/auth_context.h \
 include/grpcpp/impl/codegen/serialization_traits.h \
 include/grpcpp/impl/codegen/server_callback.h \
+include/grpcpp/impl/codegen/server_callback_impl.h \
 include/grpcpp/impl/codegen/server_context.h \
 include/grpcpp/impl/codegen/server_context_impl.h \
 include/grpcpp/impl/codegen/server_interceptor.h \
@@ -997,6 +1001,7 @@ include/grpcpp/impl/codegen/string_ref.h \
 include/grpcpp/impl/codegen/stub_options.h \
 include/grpcpp/impl/codegen/sync.h \
 include/grpcpp/impl/codegen/sync_stream.h \
+include/grpcpp/impl/codegen/sync_stream_impl.h \
 include/grpcpp/impl/codegen/time.h \
 include/grpcpp/impl/grpc_library.h \
 include/grpcpp/impl/method_handler_impl.h \
@@ -1026,11 +1031,14 @@ include/grpcpp/server_impl.h \
 include/grpcpp/server_posix.h \
 include/grpcpp/server_posix_impl.h \
 include/grpcpp/support/async_stream.h \
+include/grpcpp/support/async_stream_impl.h \
 include/grpcpp/support/async_unary_call.h \
+include/grpcpp/support/async_unary_call_impl.h \
 include/grpcpp/support/byte_buffer.h \
 include/grpcpp/support/channel_arguments.h \
 include/grpcpp/support/channel_arguments_impl.h \
 include/grpcpp/support/client_callback.h \
+include/grpcpp/support/client_callback_impl.h \
 include/grpcpp/support/client_interceptor.h \
 include/grpcpp/support/config.h \
 include/grpcpp/support/interceptor.h \
@@ -1038,6 +1046,7 @@ include/grpcpp/support/message_allocator.h \
 include/grpcpp/support/proto_buffer_reader.h \
 include/grpcpp/support/proto_buffer_writer.h \
 include/grpcpp/support/server_callback.h \
+include/grpcpp/support/server_callback_impl.h \
 include/grpcpp/support/server_interceptor.h \
 include/grpcpp/support/slice.h \
 include/grpcpp/support/status.h \
@@ -1045,6 +1054,7 @@ include/grpcpp/support/status_code_enum.h \
 include/grpcpp/support/string_ref.h \
 include/grpcpp/support/stub_options.h \
 include/grpcpp/support/sync_stream.h \
+include/grpcpp/support/sync_stream_impl.h \
 include/grpcpp/support/time.h \
 include/grpcpp/support/validate_service_config.h \
 src/core/ext/filters/client_channel/health/health.pb.c \

tools/run_tests/generated/sources_and_headers.json

@@ -10209,7 +10209,9 @@
       "include/grpc++/impl/codegen/time.h", 
       "include/grpcpp/impl/codegen/async_generic_service.h", 
       "include/grpcpp/impl/codegen/async_stream.h", 
+      "include/grpcpp/impl/codegen/async_stream_impl.h", 
       "include/grpcpp/impl/codegen/async_unary_call.h", 
+      "include/grpcpp/impl/codegen/async_unary_call_impl.h", 
       "include/grpcpp/impl/codegen/byte_buffer.h", 
       "include/grpcpp/impl/codegen/call.h", 
       "include/grpcpp/impl/codegen/call_hook.h", 
@@ -10218,6 +10220,7 @@
       "include/grpcpp/impl/codegen/callback_common.h", 
       "include/grpcpp/impl/codegen/channel_interface.h", 
       "include/grpcpp/impl/codegen/client_callback.h", 
+      "include/grpcpp/impl/codegen/client_callback_impl.h", 
       "include/grpcpp/impl/codegen/client_context.h", 
       "include/grpcpp/impl/codegen/client_context_impl.h", 
       "include/grpcpp/impl/codegen/client_interceptor.h", 
@@ -10240,6 +10243,7 @@
       "include/grpcpp/impl/codegen/security/auth_context.h", 
       "include/grpcpp/impl/codegen/serialization_traits.h", 
       "include/grpcpp/impl/codegen/server_callback.h", 
+      "include/grpcpp/impl/codegen/server_callback_impl.h", 
       "include/grpcpp/impl/codegen/server_context.h", 
       "include/grpcpp/impl/codegen/server_context_impl.h", 
       "include/grpcpp/impl/codegen/server_interceptor.h", 
@@ -10251,6 +10255,7 @@
       "include/grpcpp/impl/codegen/string_ref.h", 
       "include/grpcpp/impl/codegen/stub_options.h", 
       "include/grpcpp/impl/codegen/sync_stream.h", 
+      "include/grpcpp/impl/codegen/sync_stream_impl.h", 
       "include/grpcpp/impl/codegen/time.h"
     ], 
     "is_filegroup": true, 
@@ -10289,7 +10294,9 @@
       "include/grpc++/impl/codegen/time.h", 
       "include/grpcpp/impl/codegen/async_generic_service.h", 
       "include/grpcpp/impl/codegen/async_stream.h", 
+      "include/grpcpp/impl/codegen/async_stream_impl.h", 
       "include/grpcpp/impl/codegen/async_unary_call.h", 
+      "include/grpcpp/impl/codegen/async_unary_call_impl.h", 
       "include/grpcpp/impl/codegen/byte_buffer.h", 
       "include/grpcpp/impl/codegen/call.h", 
       "include/grpcpp/impl/codegen/call_hook.h", 
@@ -10298,6 +10305,7 @@
       "include/grpcpp/impl/codegen/callback_common.h", 
       "include/grpcpp/impl/codegen/channel_interface.h", 
       "include/grpcpp/impl/codegen/client_callback.h", 
+      "include/grpcpp/impl/codegen/client_callback_impl.h", 
       "include/grpcpp/impl/codegen/client_context.h", 
       "include/grpcpp/impl/codegen/client_context_impl.h", 
       "include/grpcpp/impl/codegen/client_interceptor.h", 
@@ -10320,6 +10328,7 @@
       "include/grpcpp/impl/codegen/security/auth_context.h", 
       "include/grpcpp/impl/codegen/serialization_traits.h", 
       "include/grpcpp/impl/codegen/server_callback.h", 
+      "include/grpcpp/impl/codegen/server_callback_impl.h", 
       "include/grpcpp/impl/codegen/server_context.h", 
       "include/grpcpp/impl/codegen/server_context_impl.h", 
       "include/grpcpp/impl/codegen/server_interceptor.h", 
@@ -10331,6 +10340,7 @@
       "include/grpcpp/impl/codegen/string_ref.h", 
       "include/grpcpp/impl/codegen/stub_options.h", 
       "include/grpcpp/impl/codegen/sync_stream.h", 
+      "include/grpcpp/impl/codegen/sync_stream_impl.h", 
       "include/grpcpp/impl/codegen/time.h"
     ], 
     "third_party": false, 
@@ -10480,11 +10490,14 @@
       "include/grpcpp/server_posix.h", 
       "include/grpcpp/server_posix_impl.h", 
       "include/grpcpp/support/async_stream.h", 
+      "include/grpcpp/support/async_stream_impl.h", 
       "include/grpcpp/support/async_unary_call.h", 
+      "include/grpcpp/support/async_unary_call_impl.h", 
       "include/grpcpp/support/byte_buffer.h", 
       "include/grpcpp/support/channel_arguments.h", 
       "include/grpcpp/support/channel_arguments_impl.h", 
       "include/grpcpp/support/client_callback.h", 
+      "include/grpcpp/support/client_callback_impl.h", 
       "include/grpcpp/support/client_interceptor.h", 
       "include/grpcpp/support/config.h", 
       "include/grpcpp/support/interceptor.h", 
@@ -10492,6 +10505,7 @@
       "include/grpcpp/support/proto_buffer_reader.h", 
       "include/grpcpp/support/proto_buffer_writer.h", 
       "include/grpcpp/support/server_callback.h", 
+      "include/grpcpp/support/server_callback_impl.h", 
       "include/grpcpp/support/server_interceptor.h", 
       "include/grpcpp/support/slice.h", 
       "include/grpcpp/support/status.h", 
@@ -10499,6 +10513,7 @@
       "include/grpcpp/support/string_ref.h", 
       "include/grpcpp/support/stub_options.h", 
       "include/grpcpp/support/sync_stream.h", 
+      "include/grpcpp/support/sync_stream_impl.h", 
       "include/grpcpp/support/time.h", 
       "include/grpcpp/support/validate_service_config.h", 
       "src/cpp/client/create_channel_internal.h", 
@@ -10608,11 +10623,14 @@
       "include/grpcpp/server_posix.h", 
       "include/grpcpp/server_posix_impl.h", 
       "include/grpcpp/support/async_stream.h", 
+      "include/grpcpp/support/async_stream_impl.h", 
       "include/grpcpp/support/async_unary_call.h", 
+      "include/grpcpp/support/async_unary_call_impl.h", 
       "include/grpcpp/support/byte_buffer.h", 
       "include/grpcpp/support/channel_arguments.h", 
       "include/grpcpp/support/channel_arguments_impl.h", 
       "include/grpcpp/support/client_callback.h", 
+      "include/grpcpp/support/client_callback_impl.h", 
       "include/grpcpp/support/client_interceptor.h", 
       "include/grpcpp/support/config.h", 
       "include/grpcpp/support/interceptor.h", 
@@ -10620,6 +10638,7 @@
       "include/grpcpp/support/proto_buffer_reader.h", 
       "include/grpcpp/support/proto_buffer_writer.h", 
       "include/grpcpp/support/server_callback.h", 
+      "include/grpcpp/support/server_callback_impl.h", 
       "include/grpcpp/support/server_interceptor.h", 
       "include/grpcpp/support/slice.h", 
       "include/grpcpp/support/status.h", 
@@ -10627,6 +10646,7 @@
       "include/grpcpp/support/string_ref.h", 
       "include/grpcpp/support/stub_options.h", 
       "include/grpcpp/support/sync_stream.h", 
+      "include/grpcpp/support/sync_stream_impl.h", 
       "include/grpcpp/support/time.h", 
       "include/grpcpp/support/validate_service_config.h", 
       "src/cpp/client/channel_cc.cc",