src: Node Tracing Controller

This commit adds support for trace-event tracing to Node.js. It provides
a mechanism to centralize tracing information generated by V8, Node
core, and userspace code. It includes:

 - A trace writer responsible for serializing traces and cycling the
   output files so that no individual file becomes to large.
 - A buffer for aggregating traces to allow for batched flushes.
 - An agent which initializes the tracing controller and ensures that
   trace serialization is done on a separate thread.
 - A set of macros for generating trace events.
 - Tests and documentation.

Author: Raymond Kang <raymondksi@gmail.com>
Author: Kelvin Jin <kelvinjin@google.com>
Author: Matthew Loring <mattloring@google.com>
Author: Jason Ginchereau <jasongin@microsoft.com>

PR-URL: https://github.com/nodejs/node/pull/9304

Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Josh Gavant <josh.gavant@outlook.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/src/tracing/agent.cc b/src/tracing/agent.cc
new file mode 100644
index 0000000000..97a3e11a2c
--- /dev/null
+++ b/src/tracing/agent.cc
@@ -0,0 +1,72 @@
+#include "tracing/agent.h"
+
+#include <sstream>
+#include <string>
+
+#include "env-inl.h"
+#include "libplatform/libplatform.h"
+
+namespace node {
+namespace tracing {
+
+using v8::platform::tracing::TraceConfig;
+
+Agent::Agent() {}
+
+void Agent::Start(v8::Platform* platform, const char* enabled_categories) {
+  platform_ = platform;
+
+  int err = uv_loop_init(&tracing_loop_);
+  CHECK_EQ(err, 0);
+
+  NodeTraceWriter* trace_writer = new NodeTraceWriter(&tracing_loop_);
+  TraceBuffer* trace_buffer = new NodeTraceBuffer(
+      NodeTraceBuffer::kBufferChunks, trace_writer, &tracing_loop_);
+
+  tracing_controller_ = new TracingController();
+
+  TraceConfig* trace_config = new TraceConfig();
+  if (enabled_categories) {
+    std::stringstream category_list(enabled_categories);
+    while (category_list.good()) {
+      std::string category;
+      getline(category_list, category, ',');
+      trace_config->AddIncludedCategory(category.c_str());
+    }
+  } else {
+    trace_config->AddIncludedCategory("v8");
+    trace_config->AddIncludedCategory("node");
+  }
+
+  // This thread should be created *after* async handles are created
+  // (within NodeTraceWriter and NodeTraceBuffer constructors).
+  // Otherwise the thread could shut down prematurely.
+  err = uv_thread_create(&thread_, ThreadCb, this);
+  CHECK_EQ(err, 0);
+
+  tracing_controller_->Initialize(trace_buffer);
+  tracing_controller_->StartTracing(trace_config);
+  v8::platform::SetTracingController(platform, tracing_controller_);
+}
+
+void Agent::Stop() {
+  if (!IsStarted()) {
+    return;
+  }
+  // Perform final Flush on TraceBuffer. We don't want the tracing controller
+  // to flush the buffer again on destruction of the V8::Platform.
+  tracing_controller_->StopTracing();
+  delete tracing_controller_;
+  // Thread should finish when the tracing loop is stopped.
+  uv_thread_join(&thread_);
+  v8::platform::SetTracingController(platform_, nullptr);
+}
+
+// static
+void Agent::ThreadCb(void* arg) {
+  Agent* agent = static_cast<Agent*>(arg);
+  uv_run(&agent->tracing_loop_, UV_RUN_DEFAULT);
+}
+
+}  // namespace tracing
+}  // namespace node