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, 31 insertions, 0 deletions

diff --git a/src/tracing/agent.h b/src/tracing/agent.h
new file mode 100644
index 0000000000..098f955192
--- /dev/null
+++ b/src/tracing/agent.h
@@ -0,0 +1,31 @@
+#ifndef SRC_TRACING_AGENT_H_
+#define SRC_TRACING_AGENT_H_
+
+#include "tracing/node_trace_buffer.h"
+#include "tracing/node_trace_writer.h"
+#include "uv.h"
+#include "v8.h"
+
+namespace node {
+namespace tracing {
+
+class Agent {
+ public:
+  explicit Agent();
+  void Start(v8::Platform* platform, const char* enabled_categories);
+  void Stop();
+
+ private:
+  bool IsStarted() { return platform_ != nullptr; }
+  static void ThreadCb(void* arg);
+
+  uv_thread_t thread_;
+  uv_loop_t tracing_loop_;
+  v8::Platform* platform_ = nullptr;
+  TracingController* tracing_controller_;
+};
+
+}  // namespace tracing
+}  // namespace node
+
+#endif  // SRC_TRACING_AGENT_H_