[channelz] HTTP/2 ztrace facility (grpc#39189)

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Closes grpc#39189

COPYBARA_INTEGRATE_REVIEW=grpc#39189 from ctiller:http2-trace 547f786
PiperOrigin-RevId: 746174350

Author: ctiller

BUILD

@@ -1243,6 +1243,7 @@ grpc_cc_library(
         "//src/core:channel_args",
         "//src/core:connectivity_state",
         "//src/core:json",
+        "//src/core:json_reader",
         "//src/core:json_writer",
         "//src/core:per_cpu",
         "//src/core:ref_counted",
@@ -2603,6 +2604,7 @@ grpc_cc_library(
     ],
     external_deps = [
         "protobuf_headers",
+        "absl/log",
     ],
     public_hdrs = [
         "include/grpcpp/ext/channelz_service_plugin.h",
@@ -4532,6 +4534,7 @@ grpc_cc_library(
         "grpc_trace",
         "//src/core:hpack_constants",
         "//src/core:hpack_encoder_table",
+        "//src/core:http2_ztrace_collector",
         "//src/core:metadata_batch",
         "//src/core:metadata_compression_traits",
         "//src/core:slice",
@@ -4685,13 +4688,16 @@ grpc_cc_library(
         "//src/core:gpr_manual_constructor",
         "//src/core:http2_settings",
         "//src/core:http2_status",
+        "//src/core:http2_ztrace_collector",
         "//src/core:init_internally",
         "//src/core:iomgr_fwd",
         "//src/core:iomgr_port",
+        "//src/core:json",
         "//src/core:match",
         "//src/core:memory_quota",
         "//src/core:metadata_batch",
         "//src/core:metadata_info",
+        "//src/core:notification",
         "//src/core:ping_abuse_policy",
         "//src/core:ping_callbacks",
         "//src/core:ping_rate_policy",

CMakeLists.txt

@@ -7566,6 +7566,7 @@ grpc_cc_library(
     ],
     deps = [
         "http2_status",
+        "json",
         "useful",
         "//:chttp2_frame",
         "//:gpr_platform",
@@ -9390,6 +9391,18 @@ grpc_cc_library(
     ],
 )
 
+grpc_cc_library(
+    name = "http2_ztrace_collector",
+    hdrs = ["ext/transport/chttp2/transport/http2_ztrace_collector.h"],
+    external_deps = [
+        "absl/container:flat_hash_set",
+    ],
+    deps = [
+        "ztrace_collector",
+        "//:chttp2_frame",
+    ],
+)
+
 ### UPB Targets
 
 grpc_upb_proto_library(

Package.swift

@@ -26,6 +26,7 @@
 #include <atomic>
 #include <cstdint>
 #include <string>
+#include <tuple>
 
 #include "absl/log/check.h"
 #include "absl/status/statusor.h"
@@ -65,9 +66,10 @@ std::string BaseNode::RenderJsonString() {
 }
 
 void BaseNode::PopulateJsonFromDataSources(Json::Object& json) {
+  DataSink sink(json);
   MutexLock lock(&data_sources_mu_);
   for (DataSource* data_source : data_sources_) {
-    data_source->AddJson(json);
+    data_source->AddData(sink);
   }
 }
 
@@ -107,6 +109,24 @@ void BaseNode::RunZTrace(
   ztrace->Run(deadline, std::move(args), event_engine, std::move(callback));
 }
 
+//
+// DataSink
+//
+
+DataSink::~DataSink() {
+  if (additional_info_ != nullptr) {
+    output_["additionalInfo"] = Json::FromObject(std::move(*additional_info_));
+  }
+}
+
+void DataSink::AddAdditionalInfo(absl::string_view name,
+                                 Json::Object additional_info) {
+  if (additional_info_ == nullptr) {
+    additional_info_ = std::make_unique<Json::Object>();
+  }
+  additional_info_->emplace(name, Json::FromObject(std::move(additional_info)));
+}
+
 //
 // DataSource
 //