Expose GetChannel and GetTopChannels Core API

grpc.def

@@ -69,6 +69,8 @@ EXPORTS
     grpc_resource_quota_unref
     grpc_resource_quota_resize
     grpc_resource_quota_arg_vtable
+    grpc_channelz_get_top_channels
+    grpc_channelz_get_channel
     grpc_insecure_channel_create_from_fd
     grpc_server_add_insecure_channel_from_fd
     grpc_use_signal

include/grpc/grpc.h

@@ -454,6 +454,29 @@ GRPCAPI void grpc_resource_quota_resize(grpc_resource_quota* resource_quota,
  */
 GRPCAPI const grpc_arg_pointer_vtable* grpc_resource_quota_arg_vtable(void);
 
+/************* CHANNELZ API *************/
+/** Channelz is under active development. The following APIs will see some
+    churn as the feature is implemented. This comment will be removed once
+    channelz is officially supported, and these APIs become stable. For now
+    you may track the progress by following this github issue:
+    https://github.com/grpc/grpc/issues/15340
+
+    the following APIs return allocated JSON strings that match the response
+    objects from the channelz proto, found here:
+    https://github.com/grpc/grpc/blob/master/src/proto/grpc/channelz/channelz.proto.
+
+    For easy conversion to protobuf, The JSON is formatted according to:
+    https://developers.google.com/protocol-buffers/docs/proto3#json. */
+
+/* Gets all root channels (i.e. channels the application has directly
+   created). This does not include subchannels nor non-top level channels.
+   The returned string is allocated and must be freed by the application. */
+GRPCAPI char* grpc_channelz_get_top_channels(intptr_t start_channel_id);
+
+/* Returns a single Channel, or else a NOT_FOUND code. The returned string
+   is allocated and must be freed by the application. */
+GRPCAPI char* grpc_channelz_get_channel(intptr_t channel_id);
+
 #ifdef __cplusplus
 }
 #endif

src/core/lib/channel/channelz_registry.cc

@@ -121,3 +121,24 @@ char* ChannelzRegistry::InternalGetTopChannels(intptr_t start_channel_id) {
 
 }  // namespace channelz
 }  // namespace grpc_core
+
+char* grpc_channelz_get_top_channels(intptr_t start_channel_id) {
+  return grpc_core::channelz::ChannelzRegistry::GetTopChannels(
+      start_channel_id);
+}
+
+char* grpc_channelz_get_channel(intptr_t channel_id) {
+  grpc_core::channelz::ChannelNode* channel_node =
+      grpc_core::channelz::ChannelzRegistry::GetChannelNode(channel_id);
+  if (channel_node == nullptr) {
+    return nullptr;
+  }
+  grpc_json* top_level_json = grpc_json_create(GRPC_JSON_OBJECT);
+  grpc_json* json = top_level_json;
+  grpc_json* channel_json = channel_node->RenderJson();
+  channel_json->key = "channel";
+  grpc_json_link_child(json, channel_json, nullptr);
+  char* json_str = grpc_json_dump_to_string(top_level_json, 0);
+  grpc_json_destroy(top_level_json);
+  return json_str;
+}

src/ruby/ext/grpc/rb_grpc_imports.generated.c

@@ -92,6 +92,8 @@ grpc_resource_quota_ref_type grpc_resource_quota_ref_import;
 grpc_resource_quota_unref_type grpc_resource_quota_unref_import;
 grpc_resource_quota_resize_type grpc_resource_quota_resize_import;
 grpc_resource_quota_arg_vtable_type grpc_resource_quota_arg_vtable_import;
+grpc_channelz_get_top_channels_type grpc_channelz_get_top_channels_import;
+grpc_channelz_get_channel_type grpc_channelz_get_channel_import;
 grpc_insecure_channel_create_from_fd_type grpc_insecure_channel_create_from_fd_import;
 grpc_server_add_insecure_channel_from_fd_type grpc_server_add_insecure_channel_from_fd_import;
 grpc_use_signal_type grpc_use_signal_import;
@@ -340,6 +342,8 @@ void grpc_rb_load_imports(HMODULE library) {
   grpc_resource_quota_unref_import = (grpc_resource_quota_unref_type) GetProcAddress(library, "grpc_resource_quota_unref");
   grpc_resource_quota_resize_import = (grpc_resource_quota_resize_type) GetProcAddress(library, "grpc_resource_quota_resize");
   grpc_resource_quota_arg_vtable_import = (grpc_resource_quota_arg_vtable_type) GetProcAddress(library, "grpc_resource_quota_arg_vtable");
+  grpc_channelz_get_top_channels_import = (grpc_channelz_get_top_channels_type) GetProcAddress(library, "grpc_channelz_get_top_channels");
+  grpc_channelz_get_channel_import = (grpc_channelz_get_channel_type) GetProcAddress(library, "grpc_channelz_get_channel");
   grpc_insecure_channel_create_from_fd_import = (grpc_insecure_channel_create_from_fd_type) GetProcAddress(library, "grpc_insecure_channel_create_from_fd");
   grpc_server_add_insecure_channel_from_fd_import = (grpc_server_add_insecure_channel_from_fd_type) GetProcAddress(library, "grpc_server_add_insecure_channel_from_fd");
   grpc_use_signal_import = (grpc_use_signal_type) GetProcAddress(library, "grpc_use_signal");

src/ruby/ext/grpc/rb_grpc_imports.generated.h

@@ -251,6 +251,12 @@ extern grpc_resource_quota_resize_type grpc_resource_quota_resize_import;
 typedef const grpc_arg_pointer_vtable*(*grpc_resource_quota_arg_vtable_type)(void);
 extern grpc_resource_quota_arg_vtable_type grpc_resource_quota_arg_vtable_import;
 #define grpc_resource_quota_arg_vtable grpc_resource_quota_arg_vtable_import
+typedef char*(*grpc_channelz_get_top_channels_type)(intptr_t start_channel_id);
+extern grpc_channelz_get_top_channels_type grpc_channelz_get_top_channels_import;
+#define grpc_channelz_get_top_channels grpc_channelz_get_top_channels_import
+typedef char*(*grpc_channelz_get_channel_type)(intptr_t channel_id);
+extern grpc_channelz_get_channel_type grpc_channelz_get_channel_import;
+#define grpc_channelz_get_channel grpc_channelz_get_channel_import
 typedef grpc_channel*(*grpc_insecure_channel_create_from_fd_type)(const char* target, int fd, const grpc_channel_args* args);
 extern grpc_insecure_channel_create_from_fd_type grpc_insecure_channel_create_from_fd_import;
 #define grpc_insecure_channel_create_from_fd grpc_insecure_channel_create_from_fd_import

test/core/channel/channelz_test.cc

@@ -95,6 +95,11 @@ void ValidateGetTopChannels(size_t expected_channels) {
   EXPECT_EQ(end->type, GRPC_JSON_TRUE);
   grpc_json_destroy(parsed_json);
   gpr_free(json_str);
+  // also check that the core API formats this correctly
+  char* core_api_json_str = grpc_channelz_get_top_channels(0);
+  grpc::testing::ValidateGetTopChannelsResponseProtoJsonTranslation(
+      core_api_json_str);
+  gpr_free(core_api_json_str);
 }
 
 class ChannelFixture {
@@ -151,6 +156,11 @@ void ValidateChannel(ChannelNode* channel, validate_channel_data_args args) {
   grpc::testing::ValidateChannelProtoJsonTranslation(json_str);
   ValidateCounters(json_str, args);
   gpr_free(json_str);
+  // also check that the core API formats this the correct way
+  char* core_api_json_str = grpc_channelz_get_channel(channel->channel_uuid());
+  grpc::testing::ValidateGetChannelResponseProtoJsonTranslation(
+      core_api_json_str);
+  gpr_free(core_api_json_str);
 }
 
 grpc_millis GetLastCallStartedMillis(ChannelNode* channel) {

test/core/surface/public_headers_must_be_c89.c

@@ -131,6 +131,8 @@ int main(int argc, char **argv) {
   printf("%lx", (unsigned long) grpc_resource_quota_unref);
   printf("%lx", (unsigned long) grpc_resource_quota_resize);
   printf("%lx", (unsigned long) grpc_resource_quota_arg_vtable);
+  printf("%lx", (unsigned long) grpc_channelz_get_top_channels);
+  printf("%lx", (unsigned long) grpc_channelz_get_channel);
   printf("%lx", (unsigned long) grpc_auth_property_iterator_next);
   printf("%lx", (unsigned long) grpc_auth_context_property_iterator);
   printf("%lx", (unsigned long) grpc_auth_context_peer_identity);

test/cpp/util/channel_trace_proto_helper.cc

@@ -77,5 +77,10 @@ void ValidateGetTopChannelsResponseProtoJsonTranslation(char* json_c_str) {
       json_c_str);
 }
 
+void ValidateGetChannelResponseProtoJsonTranslation(char* json_c_str) {
+  VaidateProtoJsonTranslation<grpc::channelz::v1::GetChannelResponse>(
+      json_c_str);
+}
+
 }  // namespace testing
 }  // namespace grpc

test/cpp/util/channel_trace_proto_helper.h

@@ -25,6 +25,7 @@ namespace testing {
 void ValidateChannelTraceProtoJsonTranslation(char* json_c_str);
 void ValidateChannelProtoJsonTranslation(char* json_c_str);
 void ValidateGetTopChannelsResponseProtoJsonTranslation(char* json_c_str);
+void ValidateGetChannelResponseProtoJsonTranslation(char* json_c_str);
 
 }  // namespace testing
 }  // namespace grpc