Implementation of 'AudioContext.getOutputTimestamp' method

third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 12 matching lines @@
  */
 
 #ifndef AudioDestinationNode_h
 #define AudioDestinationNode_h
 
 #include "modules/webaudio/AudioBuffer.h"
 #include "modules/webaudio/AudioNode.h"
 #include "platform/audio/AudioBus.h"
 #include "platform/audio/AudioIOCallback.h"
 #include "platform/audio/AudioSourceProvider.h"
+#include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
 
 class AudioBus;
 class AbstractAudioContext;
+class AudioTimestamp;
 
 class AudioDestinationHandler : public AudioHandler, public AudioIOCallback {
 public:
     AudioDestinationHandler(AudioNode&, float sampleRate);
     ~AudioDestinationHandler() override;
 
     // AudioHandler
     void process(size_t) final { } // we're pulled by hardware so this is never called
 
     // The audio hardware calls render() to get the next render quantum of audio into destinationBus.
     // It will optionally give us local/live audio input in sourceBus (if it's not 0).
-    void render(AudioBus* sourceBus, AudioBus* destinationBus, size_t numberOfFrames) final;
+    void render(AudioBus* sourceBus, AudioBus* destinationBus, size_t numberOfFrames, const WebAudioTimestamp& outputTimestamp) final;
 
     size_t currentSampleFrame() const { return acquireLoad(&m_currentSampleFrame); }
     double currentTime() const { return currentSampleFrame() / static_cast<double>(sampleRate()); }
 
     virtual unsigned long maxChannelCount() const { return 0; }
 
     virtual void startRendering() = 0;
     virtual void stopRendering() = 0;
 
+    WebAudioTimestamp outputTimestamp() const;
+
 protected:
     // LocalAudioInputProvider allows us to expose an AudioSourceProvider for local/live audio input.
     // If there is local/live audio input, we call set() with the audio input data every render quantum.
     class LocalAudioInputProvider final : public AudioSourceProvider {
     public:
         LocalAudioInputProvider()
             : m_sourceBus(AudioBus::create(2, ProcessingSizeInFrames)) // FIXME: handle non-stereo local input.
         {
         }
 
@@ skipping 12 matching lines @@
                 destinationBus->copyFrom(*m_sourceBus);
         }
 
     private:
         RefPtr<AudioBus> m_sourceBus;
     };
 
     // Counts the number of sample-frames processed by the destination.
     size_t m_currentSampleFrame;
 
+    // FIXME(Mikhail) : when allowed use std::atomic<WebAudioTimestamp> instead of mutex.

[hongchan, 2016/06/14 17:10:38]

FIXME -> TODO.

[Mikhail, 2016/06/17 09:36:57]

I've changed the approach so that it is using 'lock' and 'tryLock' from context

+    WebAudioTimestamp m_outputTimestamp;
+    mutable Mutex m_mutex;
+
     LocalAudioInputProvider m_localAudioInputProvider;
 };
 
 class AudioDestinationNode : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
     AudioDestinationHandler& audioDestinationHandler() const;
 
     unsigned long maxChannelCount() const;
 
 protected:
     AudioDestinationNode(AbstractAudioContext&);
 };
 
 } // namespace blink
 
 #endif // AudioDestinationNode_h