[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"
+#include "src/base/platform/mutex.h"
+
+namespace v8 {
+namespace platform {
+namespace tracing {
+
+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;
+
+  mutable base::Mutex mutex_;
+  size_t max_chunks_;
+  std::unique_ptr<TraceWriter> trace_writer_;
+  std::vector<std::unique_ptr<TraceBufferChunk>> chunks_;
+  size_t chunk_index_;
+  bool is_empty_ = true;
+  uint32_t current_chunk_seq_ = 1;
+};
+
+}  // namespace tracing
+}  // namespace platform
+}  // namespace v8
+
+#endif  // SRC_LIBPLATFORM_TRACING_TRACE_BUFFER_H_