[Tracing] V8 Tracing Controller

src/libplatform/tracing/trace-buffer.h

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SRC_LIBPLATFORM_TRACING_TRACE_BUFFER_H_
+#define SRC_LIBPLATFORM_TRACING_TRACE_BUFFER_H_
+
+#include <memory>
+#include <vector>
+
+#include "include/libplatform/v8-tracing.h"
+
+namespace v8 {
+namespace platform {
+namespace tracing {
+
+class TraceBufferChunk {
+ public:
+  explicit TraceBufferChunk(uint32_t seq);
+
+  void Reset(uint32_t new_seq);
+  bool IsFull() const { return next_free_ == kChunkSize; }
+  TraceObject* AddTraceEvent(size_t* event_index);
+  TraceObject* GetEventAt(size_t index) { return &chunk_[index]; }
+
+  uint32_t seq() const { return seq_; }
+  size_t size() const { return next_free_; }
+
+  static const size_t kChunkSize = 64;
+
+ private:
+  size_t next_free_;
+  TraceObject chunk_[kChunkSize];
+  uint32_t seq_;
+};

[rskang, 2016/07/12 00:58:52]

Can TraceBufferChunk go into v8-tracing.h as well? So that embedders
implementing new TraceBuffers can get access to it.

[fmeawad, 2016/07/12 21:03:19]

Done.

+
+class TraceBufferRingBuffer : public TraceBuffer {
+ public:
+  TraceBufferRingBuffer(size_t max_chunks, TraceWriter* trace_writer);
+  ~TraceBufferRingBuffer();
+
+  TraceObject* AddTraceEvent(uint64_t* handle) override;
+  TraceObject* GetEventByHandle(uint64_t handle) override;
+  bool Flush() override;
+
+ private:
+  uint64_t MakeHandle(size_t chunk_index, uint32_t chunk_seq,
+                      size_t event_index) const;
+  void ExtractHandle(uint64_t handle, size_t* chunk_index, uint32_t* chunk_seq,
+                     size_t* event_index) const;
+  size_t Capacity() const { return max_chunks_ * TraceBufferChunk::kChunkSize; }
+  size_t NextChunkIndex(size_t index) const;
+
+  size_t max_chunks_;
+  std::unique_ptr<TraceWriter> trace_writer_;
+  std::vector<std::unique_ptr<TraceBufferChunk>> chunks_;
+  size_t chunk_index_;
+  bool is_empty_;
+  uint32_t current_chunk_seq_;
+};
+
+}  // namespace tracing
+}  // namespace platform
+}  // namespace v8
+
+#endif  // SRC_LIBPLATFORM_TRACING_TRACE_BUFFER_H_