Implement suspend() and resume() for OfflineAudioContext

Source/modules/webaudio/AbstractAudioContext.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 701 matching lines @@
 
     // Find AudioBufferSourceNodes to see if we can stop playing them.
     for (AudioNode* node : m_activeSourceNodes) {
         if (node->handler().nodeType() == AudioHandler::NodeTypeAudioBufferSource) {
             AudioBufferSourceNode* sourceNode = static_cast<AudioBufferSourceNode*>(node);
             sourceNode->audioBufferSourceHandler().handleStoppableSourceNode();
         }
     }
 }
 
+void AbstractAudioContext::performPostRenderTasks()
+{
+    // Take care of AudioNode tasks where the tryLock() failed previously.
+    deferredTaskHandler().breakConnections();
+
+    // Dynamically clean up nodes which are no longer needed.
+    releaseFinishedSourceNodes();
+
+    deferredTaskHandler().handleDeferredTasks();
+    deferredTaskHandler().requestToDeleteHandlersOnMainThread();
+}
+
 void AbstractAudioContext::handlePreRenderTasks()
 {
     ASSERT(isAudioThread());
 
+    // For the precise offline audio rendering, we need these tasks to be
+    // performed every render quantum. Thus, we wait for the graph lock (rather
+    // than tryLock()) so we can run the pre-render tasks without deferring
+    // them.
+    //
+    // Also note that we do not need to run resolvePromiseForResume() here
+    // because the offline audio context keeps its own suspend/resume promise
+    // resolvers separately.
+    if (!hasRealtimeConstraint()) {
+        deferredTaskHandler().offlineContextLock();
+        deferredTaskHandler().handleDeferredTasks();
+        handleStoppableSourceNodes();
+        unlock();
+        return;
+    }
+
     // 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.
     if (tryLock()) {
         deferredTaskHandler().handleDeferredTasks();
 
         resolvePromisesForResume();
 
         // Check to see if source nodes can be stopped because the end time has passed.
         handleStoppableSourceNodes();
 
         unlock();
     }
 }
 
 void AbstractAudioContext::handlePostRenderTasks()
 {
     ASSERT(isAudioThread());
 
+    // Same as |handlePreRenderTasks()|. We force to perform the post-render
+    // tasks for the offline rendering.
+    if (!hasRealtimeConstraint()) {
+        deferredTaskHandler().offlineContextLock();
+        performPostRenderTasks();
+        unlock();
+        return;
+    }
+
     // 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).
     if (tryLock()) {
-        // Take care of AudioNode tasks where the tryLock() failed previously.
-        deferredTaskHandler().breakConnections();
-
-        // Dynamically clean up nodes which are no longer needed.
-        releaseFinishedSourceNodes();
-
-        deferredTaskHandler().handleDeferredTasks();
-        deferredTaskHandler().requestToDeleteHandlersOnMainThread();
-
+        performPostRenderTasks();
         unlock();
     }
 }
 
 void AbstractAudioContext::resolvePromisesForResumeOnMainThread()
 {
     ASSERT(isMainThread());
     AutoLocker locker(this);
 
     for (auto& resolver : m_resumeResolvers) {
@@ skipping 52 matching lines @@
     // This is called for both online and offline contexts.
     ASSERT(isMainThread());
     ASSERT(m_destinationNode);
 
     if (m_contextState == Suspended) {
         destination()->audioDestinationHandler().startRendering();
         setContextState(Running);
     }
 }
 
-void AbstractAudioContext::fireCompletionEvent()
-{
-    ASSERT(isMainThread());
-    if (!isMainThread())
-        return;
-
-    AudioBuffer* renderedBuffer = m_renderTarget.get();
-
-    // For an offline context, we set the state to closed here so that the oncomplete handler sees
-    // that the context has been closed.
-    setContextState(Closed);
-
-    ASSERT(renderedBuffer);
-    if (!renderedBuffer)
-        return;
-
-    // Avoid firing the event if the document has already gone away.
-    if (executionContext()) {
-        // Call the offline rendering completion event listener and resolve the promise too.
-        dispatchEvent(OfflineAudioCompletionEvent::create(renderedBuffer));
-        m_offlineResolver->resolve(renderedBuffer);
-    }
-}
-
 DEFINE_TRACE(AbstractAudioContext)
 {
-    visitor->trace(m_offlineResolver);
     visitor->trace(m_renderTarget);
     visitor->trace(m_destinationNode);
     visitor->trace(m_listener);
     // trace() can be called in AbstractAudioContext constructor, and
     // m_contextGraphMutex might be unavailable.
     if (m_didInitializeContextGraphMutex) {
         AutoLocker lock(this);
         visitor->trace(m_activeSourceNodes);
     } else {
         visitor->trace(m_activeSourceNodes);
     }
     visitor->trace(m_resumeResolvers);
     RefCountedGarbageCollectedEventTargetWithInlineData<AbstractAudioContext>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 SecurityOrigin* AbstractAudioContext::securityOrigin() const
 {
     if (executionContext())
         return executionContext()->securityOrigin();
 
     return nullptr;
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)