base/trace_event/trace_sampling_thread.h

// Copyright 2015 The Chromium 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 BASE_TRACE_EVENT_TRACE_SAMPLING_THREAD_H_
#define BASE_TRACE_EVENT_TRACE_SAMPLING_THREAD_H_

#include "base/synchronization/cancellation_flag.h"
#include "base/synchronization/waitable_event.h"
#include "base/trace_event/trace_event.h"

namespace base {
namespace trace_event {

class TraceBucketData;
typedef base::Callback<void(TraceBucketData*)> TraceSampleCallback;

// This object must be created on the IO thread.
class TraceSamplingThread : public PlatformThread::Delegate {
 public:
  TraceSamplingThread();
  ~TraceSamplingThread() override;

  // Implementation of PlatformThread::Delegate:
  void ThreadMain() override;

  static void DefaultSamplingCallback(TraceBucketData* bucket_data);

  void Stop();
  void WaitSamplingEventForTesting();

 private:
  friend class TraceLog;

  void GetSamples();
  // Not thread-safe. Once the ThreadMain has been called, this can no longer
  // be called.
  void RegisterSampleBucket(TRACE_EVENT_API_ATOMIC_WORD* bucket,
                            const char* const name,
                            TraceSampleCallback callback);
  // Splits a combined "category\0name" into the two component parts.
  static void ExtractCategoryAndName(const char* combined,
                                     const char** category,
                                     const char** name);
  std::vector<TraceBucketData> sample_buckets_;
  bool thread_running_;
  CancellationFlag cancellation_flag_;
  WaitableEvent waitable_event_for_testing_;
};

}  // namespace trace_event
}  // namespace base

#endif  // BASE_TRACE_EVENT_TRACE_SAMPLING_THREAD_H_