Lazy initialization of the rendering thread in OfflineAudioContext

third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp

 /*
  * Copyright (C) 2011, 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 28 matching lines @@
 #include "platform/wtf/PtrUtil.h"
 #include "public/platform/Platform.h"
 
 namespace blink {
 
 OfflineAudioDestinationHandler::OfflineAudioDestinationHandler(
     AudioNode& node,
     AudioBuffer* render_target)
     : AudioDestinationHandler(node),
       render_target_(render_target),
-      render_thread_(
-          Platform::Current()->CreateThread("offline audio renderer")),
       frames_processed_(0),
       frames_to_process_(0),
       is_rendering_started_(false),
       should_suspend_(false) {
   render_bus_ = AudioBus::Create(render_target->numberOfChannels(),
                                  AudioUtilities::kRenderQuantumFrames);
   frames_to_process_ = render_target_->length();
 
   // Node-specific defaults.
   channel_count_ = render_target_->numberOfChannels();
@@ skipping 70 matching lines @@
 void OfflineAudioDestinationHandler::StopRendering() {
   // offline audio rendering CANNOT BE stopped by JavaScript.
   NOTREACHED();
 }
 
 size_t OfflineAudioDestinationHandler::CallbackBufferSize() const {
   // The callback buffer size has no meaning for an offline context.
   NOTREACHED();
   return 0;
 }
-WebThread* OfflineAudioDestinationHandler::OfflineRenderThread() {
-  DCHECK(render_thread_);
 
-  return render_thread_.get();
+void OfflineAudioDestinationHandler::InitializeOfflineRenderThread() {
+  DCHECK(IsMainThread());
+  render_thread_ = Platform::Current()->CreateThread("offline audio renderer");
 }
 
 void OfflineAudioDestinationHandler::StartOfflineRendering() {
   DCHECK(!IsMainThread());
 
   DCHECK(render_bus_);
   if (!render_bus_)
     return;
 
   bool is_audio_context_initialized = Context()->IsDestinationInitialized();
@@ skipping 91 matching lines @@
 }
 
 void OfflineAudioDestinationHandler::NotifySuspend(size_t frame) {
   DCHECK(IsMainThread());
 
   if (Context())
     Context()->ResolveSuspendOnMainThread(frame);
 }
 
 void OfflineAudioDestinationHandler::NotifyComplete() {
+  DCHECK(IsMainThread());
+
+  // Nullify the rendering thread to save the system resource.
+  render_thread_.reset();
+
   // The OfflineAudioContext might be gone.
   if (Context())
     Context()->FireCompletionEvent();
 }
 
 bool OfflineAudioDestinationHandler::RenderIfNotSuspended(
     AudioBus* source_bus,
     AudioBus* destination_bus,
     size_t number_of_frames) {
   // We don't want denormals slowing down any of the audio processing
@@ skipping 75 matching lines @@
   SetHandler(OfflineAudioDestinationHandler::Create(*this, render_target));
 }
 
 OfflineAudioDestinationNode* OfflineAudioDestinationNode::Create(
     BaseAudioContext* context,
     AudioBuffer* render_target) {
   return new OfflineAudioDestinationNode(*context, render_target);
 }
 
 }  // namespace blink