Initialize AudioContext on constructor to increase currentTime in real-time.

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 101 matching lines @@
     , m_isInitialized(false)
     , m_isAudioThreadFinished(false)
     , m_destinationNode(nullptr)
     , m_isDeletionScheduled(false)
     , m_automaticPullNodesNeedUpdating(false)
     , m_connectionCount(0)
     , m_audioThread(0)
     , m_graphOwnerThread(UndefinedThreadIdentifier)
     , m_isOfflineContext(false)
 {
+    m_destinationNode = DefaultAudioDestinationNode::create(this);
+
     constructCommon();
-
-    m_destinationNode = DefaultAudioDestinationNode::create(this);

[Raymond Toy, 2014/05/27 17:49:45]

Why are these two lines swapped?

[KhNo, 2014/05/28 14:39:51]

It must be initialized after creating m_destinationNode. In initializae().
m_destinationNode is used.

 }
 
 // Constructor for offline (non-realtime) rendering.
 AudioContext::AudioContext(Document* document, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate)
     : ActiveDOMObject(document)
     , m_isStopScheduled(false)
     , m_isCleared(false)
     , m_isInitialized(false)
     , m_isAudioThreadFinished(false)
     , m_destinationNode(nullptr)
     , m_automaticPullNodesNeedUpdating(false)
     , m_connectionCount(0)
     , m_audioThread(0)
     , m_graphOwnerThread(UndefinedThreadIdentifier)
     , m_isOfflineContext(true)
 {
-    constructCommon();
-
     // Create a new destination for offline rendering.
     m_renderTarget = AudioBuffer::create(numberOfChannels, numberOfFrames, sampleRate);
     if (m_renderTarget.get())
         m_destinationNode = OfflineAudioDestinationNode::create(this, m_renderTarget.get());
+
+    constructCommon();

[Raymond Toy, 2014/05/27 17:49:45]

Why is this moved from the beginning to the end?

[KhNo, 2014/05/28 14:39:51]

It must be initialized after creating m_destinationNode. In initializae().
m_destinationNode is used.

 }
 
 void AudioContext::constructCommon()
 {
     ScriptWrappable::init(this);
 
     FFTFrame::initialize();
 
     m_listener = AudioListener::create();
+
+    initialize();
 }
 
 AudioContext::~AudioContext()
 {
 #if DEBUG_AUDIONODE_REFERENCES
     fprintf(stderr, "%p: AudioContext::~AudioContext()\n", this);
 #endif
     // AudioNodes keep a reference to their context, so there should be no way to be in the destructor if there are still AudioNodes around.
     ASSERT(!m_isInitialized);
     ASSERT(!m_nodesToDelete.size());
     ASSERT(!m_referencedNodes.size());
     ASSERT(!m_finishedNodes.size());
     ASSERT(!m_automaticPullNodes.size());
     if (m_automaticPullNodesNeedUpdating)
         m_renderingAutomaticPullNodes.resize(m_automaticPullNodes.size());
     ASSERT(!m_renderingAutomaticPullNodes.size());
 }
 
-void AudioContext::lazyInitialize()
+void AudioContext::initialize()
 {
-    if (!m_isInitialized) {
-        // Don't allow the context to initialize a second time after it's already been explicitly uninitialized.
-        ASSERT(!m_isAudioThreadFinished);
-        if (!m_isAudioThreadFinished) {
-            // Creation of a destination node should not start the audio HW. The
-            // creation of any other AudioNode will initialize the audio HW and start processing
-            if (m_destinationNode.get()) {
-                m_destinationNode->initialize();
+    // Don't allow the context to initialize a second time after it's already been explicitly uninitialized.
+    if (isInitialized())
+        return;
 
-                if (!isOfflineContext()) {
-                    // This starts the audio thread. The destination node's provideInput() method will now be called repeatedly to render audio.
-                    // Each time provideInput() is called, a portion of the audio stream is rendered. Let's call this time period a "render quantum".
-                    // NOTE: for now default AudioContext does not need an explicit startRendering() call from JavaScript.
-                    // We may want to consider requiring it for symmetry with OfflineAudioContext.
-                    m_destinationNode->startRendering();

[Raymond Toy, 2014/05/27 17:49:45]

Don't we still need to call startRendering()?

[KhNo, 2014/05/28 14:39:51]

This is my big mistake. Sorry about it. It must be there.

-                    ++s_hardwareContextCount;
-                }
+    if (m_destinationNode) {
+        if (!isOfflineContext())
+            ++s_hardwareContextCount;
 
-                m_isInitialized = true;
-            }
-        }
+        m_destinationNode->initialize();
+        m_isInitialized = true;
     }
 }
 
 void AudioContext::clear()
 {
     // 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.
@@ skipping 764 matching lines @@
 {
     visitor->trace(m_renderTarget);
     visitor->trace(m_destinationNode);
     visitor->trace(m_listener);
     visitor->trace(m_dirtySummingJunctions);
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)