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      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_
     55