Implementation of 'AudioContext.getOutputTimestamp' method

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

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 #include "modules/webaudio/AudioDestinationNode.h"
+
 #include "modules/webaudio/AbstractAudioContext.h"
 #include "modules/webaudio/AudioNodeInput.h"
 #include "modules/webaudio/AudioNodeOutput.h"
 #include "platform/audio/AudioUtilities.h"
 #include "platform/audio/DenormalDisabler.h"
 #include "wtf/Atomics.h"
 
 namespace blink {
 
 AudioDestinationHandler::AudioDestinationHandler(AudioNode& node, float sampleRate)
     : AudioHandler(NodeTypeDestination, node, sampleRate)
     , m_currentSampleFrame(0)
 {
     addInput();
 }
 
 AudioDestinationHandler::~AudioDestinationHandler()
 {
     ASSERT(!isInitialized());
 }
 
-void AudioDestinationHandler::render(AudioBus* sourceBus, AudioBus* destinationBus, size_t numberOfFrames)
+void AudioDestinationHandler::render(AudioBus* sourceBus, AudioBus* destinationBus, size_t numberOfFrames, const WebAudioTimestamp& outputTimestamp)
 {
     // We don't want denormals slowing down any of the audio processing
     // since they can very seriously hurt performance.
     // This will take care of all AudioNodes because they all process within this scope.
     DenormalDisabler denormalDisabler;
 
     // Need to check if the context actually alive. Otherwise the subsequent
     // steps will fail. If the context is not alive somehow, return immediately
     // and do nothing.
     //
     // TODO(hongchan): because the context can go away while rendering, so this
     // check cannot guarantee the safe execution of the following steps.
     ASSERT(context());
     if (!context())
         return;
 
     context()->deferredTaskHandler().setAudioThreadToCurrentThread();
 
     // If the destination node is not initialized, pass the silence to the final
     // audio destination (one step before the FIFO). This check is for the case
     // where the destination is in the middle of tearing down process.
     if (!isInitialized()) {
         destinationBus->zero();
         return;
     }
 
     // Let the context take care of any business at the start of each render quantum.
     context()->handlePreRenderTasks();
 
+    // Set the output device audio stream timestamp.
+    context()->setWebAudioTimestamp(outputTimestamp);

[hongchan, 2016/06/20 16:05:21]

I prefer to have this inside of handlePreRenderTasks(). This is a part of
pre-render task.

+
     // Prepare the local audio input provider for this render quantum.
     if (sourceBus)
         m_localAudioInputProvider.set(sourceBus);
 
     ASSERT(numberOfInputs() >= 1);
     if (numberOfInputs() < 1) {
         destinationBus->zero();
         return;
     }
     // This will cause the node(s) connected to us to process, which in turn will pull on their input(s),
@@ skipping 30 matching lines @@
     return static_cast<AudioDestinationHandler&>(handler());
 }
 
 unsigned long AudioDestinationNode::maxChannelCount() const
 {
     return audioDestinationHandler().maxChannelCount();
 }
 
 } // namespace blink