src: refactor default trace writer out of agent

The agent code is supposed to manage multiple writers/clients.
Adding the default writer into the mix breaks that encapsulation.
Instead, manage default options through a separate "virtual"
default client handle, and keep the file writer management
all to the actual users.

PR-URL: https://github.com/nodejs/node/pull/21867
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/src/node_trace_events.cc b/src/node_trace_events.cc
index 06063a449b9..d59b9255579 100644
--- a/src/node_trace_events.cc
+++ b/src/node_trace_events.cc
@@ -58,7 +58,7 @@ void NodeCategorySet::New(const FunctionCallbackInfo<Value>& args) {
     if (!*val) return;
     categories.emplace(*val);
   }
-  CHECK_NOT_NULL(env->tracing_agent());
+  CHECK_NOT_NULL(env->tracing_agent_writer());
   new NodeCategorySet(env, args.This(), std::move(categories));
 }
 
@@ -69,7 +69,7 @@ void NodeCategorySet::Enable(const FunctionCallbackInfo<Value>& args) {
   CHECK_NOT_NULL(category_set);
   const auto& categories = category_set->GetCategories();
   if (!category_set->enabled_ && !categories.empty()) {
-    env->tracing_agent()->Enable(categories);
+    env->tracing_agent_writer()->Enable(categories);
     category_set->enabled_ = true;
   }
 }
@@ -81,14 +81,15 @@ void NodeCategorySet::Disable(const FunctionCallbackInfo<Value>& args) {
   CHECK_NOT_NULL(category_set);
   const auto& categories = category_set->GetCategories();
   if (category_set->enabled_ && !categories.empty()) {
-    env->tracing_agent()->Disable(categories);
+    env->tracing_agent_writer()->Disable(categories);
     category_set->enabled_ = false;
   }
 }
 
 void GetEnabledCategories(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
-  std::string categories = env->tracing_agent()->GetEnabledCategories();
+  std::string categories =
+      env->tracing_agent_writer()->agent()->GetEnabledCategories();
   if (!categories.empty()) {
     args.GetReturnValue().Set(
       String::NewFromUtf8(env->isolate(),