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, 89 insertions, 0 deletions

diff --git a/src/tracing/node_trace_buffer.h b/src/tracing/node_trace_buffer.h
new file mode 100644
index 0000000000..619799fdb2
--- /dev/null
+++ b/src/tracing/node_trace_buffer.h
@@ -0,0 +1,89 @@
+#ifndef SRC_NODE_TRACE_BUFFER_H_
+#define SRC_NODE_TRACE_BUFFER_H_
+
+#include "node_mutex.h"
+#include "tracing/node_trace_writer.h"
+#include "libplatform/v8-tracing.h"
+
+#include <atomic>
+
+namespace node {
+namespace tracing {
+
+using v8::platform::tracing::TraceBuffer;
+using v8::platform::tracing::TraceBufferChunk;
+using v8::platform::tracing::TraceObject;
+
+// forward declaration
+class NodeTraceBuffer;
+
+class InternalTraceBuffer {
+ public:
+  InternalTraceBuffer(size_t max_chunks, uint32_t id,
+                      NodeTraceWriter* trace_writer,
+                      NodeTraceBuffer* external_buffer);
+
+  TraceObject* AddTraceEvent(uint64_t* handle);
+  TraceObject* GetEventByHandle(uint64_t handle);
+  void Flush(bool blocking);
+  bool IsFull() const {
+    return total_chunks_ == max_chunks_ && chunks_[total_chunks_ - 1]->IsFull();
+  }
+  bool IsFlushing() const {
+    return flushing_;
+  }
+
+ private:
+  uint64_t MakeHandle(size_t chunk_index, uint32_t chunk_seq,
+                      size_t event_index) const;
+  void ExtractHandle(uint64_t handle, uint32_t* buffer_id, size_t* chunk_index,
+                     uint32_t* chunk_seq, size_t* event_index) const;
+  size_t Capacity() const { return max_chunks_ * TraceBufferChunk::kChunkSize; }
+
+  Mutex mutex_;
+  bool flushing_;
+  size_t max_chunks_;
+  NodeTraceWriter* trace_writer_;
+  NodeTraceBuffer* external_buffer_;
+  std::vector<std::unique_ptr<TraceBufferChunk>> chunks_;
+  size_t total_chunks_ = 0;
+  uint32_t current_chunk_seq_ = 1;
+  uint32_t id_;
+};
+
+class NodeTraceBuffer : public TraceBuffer {
+ public:
+  NodeTraceBuffer(size_t max_chunks, NodeTraceWriter* trace_writer,
+                  uv_loop_t* tracing_loop);
+  ~NodeTraceBuffer();
+
+  TraceObject* AddTraceEvent(uint64_t* handle) override;
+  TraceObject* GetEventByHandle(uint64_t handle) override;
+  bool Flush() override;
+
+  static const size_t kBufferChunks = 1024;
+
+ private:
+  bool TryLoadAvailableBuffer();
+  static void NonBlockingFlushSignalCb(uv_async_t* signal);
+  static void ExitSignalCb(uv_async_t* signal);
+
+  uv_loop_t* tracing_loop_;
+  uv_async_t flush_signal_;
+  uv_async_t exit_signal_;
+  bool exited_ = false;
+  // Used exclusively for exit logic.
+  Mutex exit_mutex_;
+  // Used to wait until async handles have been closed.
+  ConditionVariable exit_cond_;
+  std::unique_ptr<NodeTraceWriter> trace_writer_;
+  // TODO: Change std::atomic to something less contentious.
+  std::atomic<InternalTraceBuffer*> current_buf_;
+  InternalTraceBuffer buffer1_;
+  InternalTraceBuffer buffer2_;
+};
+
+}  // namespace tracing
+}  // namespace node
+
+#endif  // SRC_NODE_TRACING_CONTROLLER_H_