src: trace_event: secondary storage for metadata

Metadata trace-events should be held in secondary storage so that they
can be periodically reemitted. This change establishes the secondary
storage and ensures that events are reemitted on each flush.

PR-URL: https://github.com/nodejs/node/pull/20900
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 27 insertions, 0 deletions

diff --git a/src/tracing/agent.cc b/src/tracing/agent.cc
index fd5cb3387b..103df55da5 100644
--- a/src/tracing/agent.cc
+++ b/src/tracing/agent.cc
@@ -1,6 +1,7 @@
 #include "tracing/agent.h"
 
 #include <string>
+#include "trace_event.h"
 #include "tracing/node_trace_buffer.h"
 #include "debug_utils.h"
 #include "env-inl.h"
@@ -207,9 +208,35 @@ void Agent::AppendTraceEvent(TraceObject* trace_event) {
 }
 
 void Agent::Flush(bool blocking) {
+  for (const auto& event : metadata_events_)
+    AppendTraceEvent(event.get());
+
   for (const auto& id_writer : writers_)
     id_writer.second->Flush(blocking);
 }
 
+void TracingController::AddMetadataEvent(
+    const unsigned char* category_group_enabled,
+    const char* name,
+    int num_args,
+    const char** arg_names,
+    const unsigned char* arg_types,
+    const uint64_t* arg_values,
+    std::unique_ptr<v8::ConvertableToTraceFormat>* convertable_values,
+    unsigned int flags) {
+  std::unique_ptr<TraceObject> trace_event(new TraceObject);
+  trace_event->Initialize(
+      TRACE_EVENT_PHASE_METADATA, category_group_enabled, name,
+      node::tracing::kGlobalScope,  // scope
+      node::tracing::kNoId,         // id
+      node::tracing::kNoId,         // bind_id
+      num_args, arg_names, arg_types, arg_values, convertable_values,
+      TRACE_EVENT_FLAG_NONE,
+      CurrentTimestampMicroseconds(),
+      CurrentCpuTimestampMicroseconds());
+  node::tracing::TraceEventHelper::GetAgent()->AddMetadataEvent(
+      std::move(trace_event));
+}
+
 }  // namespace tracing
 }  // namespace node