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

Source/modules/webaudio/AudioContext.cpp

Index: Source/modules/webaudio/AudioContext.cpp
diff --git a/Source/modules/webaudio/AudioContext.cpp b/Source/modules/webaudio/AudioContext.cpp
index 64cfcec8f094668af32aead6d81a4327cc3765b1..cdb24cae014f4ae3b28ecc845264e75384494ea3 100644
--- a/Source/modules/webaudio/AudioContext.cpp
+++ b/Source/modules/webaudio/AudioContext.cpp
@@ -191,6 +191,11 @@ void AudioContext::initialize()
 
 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();
@@ -756,6 +761,21 @@ void AudioContext::handleDeferredAudioNodeTasks()
     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());
@@ -817,10 +837,12 @@ void AudioContext::deleteMarkedNodes()
             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();
@@ -965,6 +987,9 @@ 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);
 }