base/trace_event/trace_sampling_thread.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_TRACE_EVENT_TRACE_SAMPLING_THREAD_H_
   6 #define BASE_TRACE_EVENT_TRACE_SAMPLING_THREAD_H_
   7
   8 #include "base/synchronization/cancellation_flag.h"
   9 #include "base/synchronization/waitable_event.h"
  10 #include "base/trace_event/trace_event.h"
  11
  12 namespace base {
  13 namespace trace_event {
  14
  15 class TraceBucketData;
  16 typedef base::Callback<void(TraceBucketData*)> TraceSampleCallback;
  17
  18 // This object must be created on the IO thread.
  19 class TraceSamplingThread : public PlatformThread::Delegate {
  20  public:
  21   TraceSamplingThread();
  22   ~TraceSamplingThread() override;
  23
  24   // Implementation of PlatformThread::Delegate:
  25   void ThreadMain() override;
  26
  27   static void DefaultSamplingCallback(TraceBucketData* bucket_data);
  28
  29   void Stop();
  30   void WaitSamplingEventForTesting();
  31
  32  private:
  33   friend class TraceLog;
  34
  35   void GetSamples();
  36   // Not thread-safe. Once the ThreadMain has been called, this can no longer
  37   // be called.
  38   void RegisterSampleBucket(TRACE_EVENT_API_ATOMIC_WORD* bucket,
  39                             const char* const name,
  40                             TraceSampleCallback callback);
  41   // Splits a combined "category\0name" into the two component parts.
  42   static void ExtractCategoryAndName(const char* combined,
  43                                      const char** category,
  44                                      const char** name);
  45   std::vector<TraceBucketData> sample_buckets_;
  46   bool thread_running_;
  47   CancellationFlag cancellation_flag_;
  48   WaitableEvent waitable_event_for_testing_;
  49 };
  50
  51 }  // namespace trace_event
  52 }  // namespace base
  53
  54 #endif  // BASE_TRACE_EVENT_TRACE_SAMPLING_THREAD_H_