Merge 142687

Source/WebCore/Modules/webaudio/PannerNode.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 85 matching lines @@
         return;
     }
 
     AudioBus* source = input(0)->bus();
 
     if (!source) {
         destination->zero();
         return;
     }
 
-    // Apply the panning effect.
-    double azimuth;
-    double elevation;
-    getAzimuthElevation(&azimuth, &elevation);
-    m_panner->pan(azimuth, elevation, source, destination, framesToProcess);
+    // The audio thread can't block on this lock, so we call tryLock() instead.
+    MutexTryLocker tryLocker(m_pannerLock);
+    if (tryLocker.locked()) {
+        // Apply the panning effect.
+        double azimuth;
+        double elevation;
+        getAzimuthElevation(&azimuth, &elevation);
+        m_panner->pan(azimuth, elevation, source, destination, framesToProcess);
 
-    // Get the distance and cone gain.
-    double totalGain = distanceConeGain();
+        // Get the distance and cone gain.
+        double totalGain = distanceConeGain();
 
-    // Snap to desired gain at the beginning.
-    if (m_lastGain == -1.0)
-        m_lastGain = totalGain;
+        // Snap to desired gain at the beginning.
+        if (m_lastGain == -1.0)
+            m_lastGain = totalGain;
         
-    // Apply gain in-place with de-zippering.
-    destination->copyWithGainFrom(*destination, &m_lastGain, totalGain);
+        // Apply gain in-place with de-zippering.
+        destination->copyWithGainFrom(*destination, &m_lastGain, totalGain);
+    } else {
+        // Too bad - The tryLock() failed. We must be in the middle of changing the panner.
+        destination->zero();
+    }
 }
 
 void PannerNode::reset()
 {
     m_lastGain = -1.0; // force to snap to initial gain
     if (m_panner.get())
         m_panner->reset();
 }
 
 void PannerNode::initialize()
@@ skipping 19 matching lines @@
 {
     return context()->listener();
 }
 
 void PannerNode::setPanningModel(unsigned short model, ExceptionCode& ec)
 {
     switch (model) {
     case EQUALPOWER:
     case HRTF:
         if (!m_panner.get() || model != m_panningModel) {
+            // This synchronizes with process().
+            MutexLocker processLocker(m_pannerLock);
+            
             OwnPtr<Panner> newPanner = Panner::create(model, sampleRate());
             m_panner = newPanner.release();
             m_panningModel = model;
         }
         break;
     case SOUNDFIELD:
         // FIXME: Implement sound field model. See // https://bugs.webkit.org/show_bug.cgi?id=77367.
         // For now, fall through to throw an exception.
     default:
         ec = NOT_SUPPORTED_ERR;
@@ skipping 165 matching lines @@
                 AudioNode* connectedNode = connectedOutput->node();
                 notifyAudioSourcesConnectedToNode(connectedNode); // recurse
             }
         }
     }
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)