Defer changes to the channel count mode to the pre or post-render phase

Source/modules/webaudio/AudioContext.cpp

 /*
  * 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 659 matching lines @@
 }
 
 void AudioContext::handlePreRenderTasks()
 {
     ASSERT(isAudioThread());
 
     // At the beginning of every render quantum, try to update the internal rendering graph state (from main thread changes).
     // It's OK if the tryLock() fails, we'll just take slightly longer to pick up the changes.
     bool mustReleaseLock;
     if (tryLock(mustReleaseLock)) {
+        // Update the channel count mode.
+        updateChangedChannelCountMode();
+
         // Fixup the state of any dirty AudioSummingJunctions and AudioNodeOutputs.
         handleDirtyAudioSummingJunctions();
         handleDirtyAudioNodeOutputs();
 
         updateAutomaticPullNodes();
 
         if (mustReleaseLock)
             unlock();
     }
 }
 
 void AudioContext::handlePostRenderTasks()
 {
     ASSERT(isAudioThread());
 
     // Must use a tryLock() here too.  Don't worry, the lock will very rarely be contended and this method is called frequently.
     // The worst that can happen is that there will be some nodes which will take slightly longer than usual to be deleted or removed
     // from the render graph (in which case they'll render silence).
     bool mustReleaseLock;
     if (tryLock(mustReleaseLock)) {
+        // Update the channel count mode.
+        updateChangedChannelCountMode();
+
         // Take care of AudioNode tasks where the tryLock() failed previously.
         handleDeferredAudioNodeTasks();
 
         // Dynamically clean up nodes which are no longer needed.
         derefFinishedSourceNodes();
 
         // Fixup the state of any dirty AudioSummingJunctions and AudioNodeOutputs.
         handleDirtyAudioSummingJunctions();
         handleDirtyAudioNodeOutputs();
 
@@ skipping 177 matching lines @@
 {
     visitor->trace(m_renderTarget);
     visitor->trace(m_destinationNode);
     visitor->trace(m_listener);
     visitor->trace(m_referencedNodes);
     visitor->trace(m_liveNodes);
     visitor->trace(m_liveAudioSummingJunctions);
     EventTargetWithInlineData::trace(visitor);
 }
 
+void AudioContext::addChangedChannelCountMode(AudioNode* node)
+{
+    ASSERT(isGraphOwner());
+    ASSERT(isMainThread());
+    m_deferredCountModeChange.add(node);
+}
+
+void AudioContext::removeChangedChannelCountMode(AudioNode* node)
+{
+    ASSERT(isGraphOwner());
+
+    m_deferredCountModeChange.remove(node);
+}
+
+void AudioContext::updateChangedChannelCountMode()
+{
+    ASSERT(isGraphOwner());
+
+    for (HashSet<AudioNode*>::iterator k = m_deferredCountModeChange.begin(); k != m_deferredCountModeChange.end(); ++k)
+        (*k)->updateChannelCountMode();
+
+    m_deferredCountModeChange.clear();
+}
+
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)