Oilpan: WebAudio: Apply the weak HashMap pattern to remove an entry from AudioContext::m_dirtyAudio…

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 173 matching lines @@
             m_destinationNode->startRendering();
             ++s_hardwareContextCount;
         }
 
         m_isInitialized = true;
     }
 }
 
 void AudioContext::clear()
 {
+#if ENABLE(OILPAN)
+    // We need to run disposers before destructing m_contextGraphMutex.
+    m_liveAudioSummingJunctions.clear();
+#endif
+
     // We have to release our reference to the destination node before the context will ever be deleted since the destination node holds a reference to the context.
     if (m_destinationNode)
         m_destinationNode.clear();
 
     // Audio thread is dead. Nobody will schedule node deletion action. Let's do it ourselves.
     do {
         m_nodesToDelete.appendVector(m_nodesMarkedForDeletion);
         m_nodesMarkedForDeletion.clear();
         deleteMarkedNodes();
     } while (m_nodesToDelete.size());
@@ skipping 545 matching lines @@
 
     for (unsigned i = 0; i < m_deferredBreakConnectionList.size(); ++i)
         m_deferredBreakConnectionList[i]->breakConnectionWithLock();
     m_deferredBreakConnectionList.clear();
 
     for (unsigned i = 0; i < m_deferredFinishDerefList.size(); ++i)
         m_deferredFinishDerefList[i]->finishDeref();
     m_deferredFinishDerefList.clear();
 }
 
+#if ENABLE(OILPAN)
+void AudioContext::registerLiveAudioSummingJunction(AudioSummingJunction& junction)
+{
+    ASSERT(isMainThread());
+    m_liveAudioSummingJunctions.add(&junction, adoptPtr(new AudioSummingJunctionDisposer(junction)));
+}
+
+AudioContext::AudioSummingJunctionDisposer::~AudioSummingJunctionDisposer()
+{
+    ASSERT(isMainThread());
+    AudioContext::AutoLocker locker(m_junction.context());

[haraken, 2014/07/18 09:49:30]

Won't this cause a dead lock? removeMarkedSummingJunction also tries to acquire
a lock on the AudioContext.

[tkent, 2014/07/18 09:52:16]

No.  AutoLocker supports reentrancy.  If the current thread already has the
lock, AutoLocker doesn't block the thread.

[tkent, 2014/07/18 09:54:22]

Anyway, this AutoLocker is redundant and unnecessary.

[haraken, 2014/07/18 10:01:01]

Makes sense. However, I think you can just drop this AutoLocker, since
removeMarkedSummingJunction always acquires the lock.

[tkent, 2014/07/18 13:43:09]

Indeed.

+    m_junction.context()->removeMarkedSummingJunction(&m_junction);
+}
+#endif
+
 void AudioContext::markForDeletion(AudioNode* node)
 {
     ASSERT(isGraphOwner());
 
     if (!isInitialized())
         m_nodesToDelete.append(node);
     else
         m_nodesMarkedForDeletion.append(node);
 
     // This is probably the best time for us to remove the node from automatic pull list,
@@ skipping 41 matching lines @@
 
     // Protect this object from being deleted before we release the mutex locked by AutoLocker.
     RefPtrWillBeRawPtr<AudioContext> protect(this);
     {
         AutoLocker locker(this);
 
         while (size_t n = m_nodesToDelete.size()) {
             AudioNode* node = m_nodesToDelete[n - 1];
             m_nodesToDelete.removeLast();
 
+#if !ENABLE(OILPAN)

[haraken, 2014/07/18 10:01:00]

Probably can we keep this code? In terms of performance, it would be better to
explicitly remove entries rather than relying on weak processing.

[tkent, 2014/07/18 13:43:08]

Yeah, It's ok to keep this.

             // Before deleting the node, clear out any AudioNodeInputs from m_dirtySummingJunctions.
             unsigned numberOfInputs = node->numberOfInputs();
             for (unsigned i = 0; i < numberOfInputs; ++i)
                 m_dirtySummingJunctions.remove(node->input(i));
+#endif
 
             // Before deleting the node, clear out any AudioNodeOutputs from m_dirtyAudioNodeOutputs.
             unsigned numberOfOutputs = node->numberOfOutputs();
             for (unsigned i = 0; i < numberOfOutputs; ++i)
                 m_dirtyAudioNodeOutputs.remove(node->output(i));
 
 #if ENABLE(OILPAN)
             // Finally, clear the keep alive handle that keeps this
             // object from being collected.
             node->clearKeepAlive();
@@ skipping 124 matching lines @@
         // Call the offline rendering completion event listener.
         dispatchEvent(OfflineAudioCompletionEvent::create(renderedBuffer));
     }
 }
 
 void AudioContext::trace(Visitor* visitor)
 {
     visitor->trace(m_renderTarget);
     visitor->trace(m_destinationNode);
     visitor->trace(m_listener);
+#if ENABLE(OILPAN)
+    visitor->trace(m_liveAudioSummingJunctions);
+#endif
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)