Decouple 'give me more data' and 'rendered end of stream' audio callbacks.

content/renderer/media/audio_renderer_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Audio rendering unit utilizing AudioDevice.
 //
 // This class lives inside three threads during it's lifetime, namely:
 // 1. Render thread.
 //    This object is created on the render thread.
 // 2. Pipeline thread
 //    OnInitialize() is called here with the audio format.
 //    Play/Pause/Seek also happens here.
 // 3. Audio thread created by the AudioDevice.
 //    Render() is called here where audio data is decoded into raw PCM data.
 
 #ifndef CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
 #pragma once
 
 #include <vector>
 
+#include "base/callback.h"
+#include "base/cancelable_callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop_proxy.h"
 #include "base/synchronization/lock.h"
+#include "base/time.h"
 #include "content/renderer/media/audio_device.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_renderer_sink.h"
 #include "media/filters/audio_renderer_base.h"
 
 class AudioMessageFilter;
 
 class CONTENT_EXPORT AudioRendererImpl
     : public media::AudioRendererBase,
+      NON_EXPORTED_BASE(public base::SupportsWeakPtr<AudioRendererImpl>),
       NON_EXPORTED_BASE(public media::AudioRendererSink::RenderCallback) {
  public:
   // Methods called on Render thread ------------------------------------------
   // An AudioRendererSink is used as the destination for the rendered audio.
   explicit AudioRendererImpl(media::AudioRendererSink* sink);
   virtual ~AudioRendererImpl();
 
   // Methods called on pipeline thread ----------------------------------------
   // media::Filter implementation.
   virtual void SetPlaybackRate(float rate) OVERRIDE;
@@ skipping 15 matching lines @@
   virtual void OnRenderEndOfStream() OVERRIDE;
 
  private:
   // For access to constructor and IO thread methods.
   friend class AudioRendererImplTest;
   friend class DelegateCaller;
   FRIEND_TEST_ALL_PREFIXES(AudioRendererImplTest, Stop);
   FRIEND_TEST_ALL_PREFIXES(AudioRendererImplTest,
                            DestroyedMessageLoop_ConsumeAudioSamples);
   FRIEND_TEST_ALL_PREFIXES(AudioRendererImplTest, UpdateEarliestEndTime);
+
+  enum state { NOT_PLAYING, PLAYING, ENDED_EVENT_SCHEDULED, STOPPED };
+
+  // Thread-safe accessor. Not necessary on all current platforms,
+  // state can be set to STOPPED only on the pipeline thread,
+  // but better to have it safe for the future.
+  bool stopped() {
+    base::AutoLock auto_lock(audio_renderer_impl_lock_);
+    return (state_ == STOPPED);
+  }
+
   // Helper methods.
   // Convert number of bytes to duration of time using information about the
   // number of channels, sample rate and sample bits.
   base::TimeDelta ConvertToDuration(int bytes);
 
   // Methods called on pipeline thread ----------------------------------------
   void DoPlay();
   void DoPause();
   void DoSeek();
+  void DoSignalEndOfStream();
+  // We cannot set pipeline message loop in the constructor/initializer because
+  // message loop is not created at that moment. So set it after it is created,
+  // in the DoPlay(). Also DCHECK() that all functions we are expecting to be
+  // called from the pipeline message loop are actually called from it.
+  void DoSetOrCheckMessageLoopProxy();
 
   // media::AudioRendererSink::RenderCallback implementation.
   virtual size_t Render(const std::vector<float*>& audio_data,
                         size_t number_of_frames,
                         size_t audio_delay_milliseconds) OVERRIDE;
   virtual void OnRenderError() OVERRIDE;
 
+  // Returns current message loop proxy.
+  // Made virtual so test can override --  tests use
+  // ChildProcess::current()->io_message_loop_proxy() instead of
+  // MessageLoop::current()->message_loop_proxy().
+  virtual base::MessageLoopProxy* current_message_loop_proxy() {
+    return MessageLoop::current()->message_loop_proxy();
+  }
+
+  // Returns delay in ms before call to OnRenderEndOfStream().
+  // Made virtual so test can override.
+  virtual int64 OnRenderEndOfStreamDelay();
+
   // Accessors used by tests.
-  base::Time earliest_end_time() const {
+  base::Time earliest_end_time() {
     return earliest_end_time_;
   }
 
   void set_earliest_end_time(const base::Time& earliest_end_time) {
     earliest_end_time_ = earliest_end_time;
   }
 
   uint32 bytes_per_second() const {
     return bytes_per_second_;
   }
 
   // Estimate earliest time when current buffer can stop playing.
   void UpdateEarliestEndTime(int bytes_filled,
                              base::TimeDelta request_delay,
                              base::Time time_now);
 
+  // Lock protecting data that can be accessed form pipeline and audio threads.
+  base::Lock audio_renderer_impl_lock_;
+
   // Used to calculate audio delay given bytes.
   uint32 bytes_per_second_;
 
-  // A flag that indicates this filter is called to stop.
-  bool stopped_;
+  // Current state.
+  state state_;
 
   // The sink (destination) for rendered audio.
   scoped_refptr<media::AudioRendererSink> sink_;
 
   // Set to true when OnInitialize() is called.
   bool is_initialized_;
 
   // We're supposed to know amount of audio data OS or hardware buffered, but
   // that is not always so -- on my Linux box
   // AudioBuffersState::hardware_delay_bytes never reaches 0.
   //
   // As a result we cannot use it to find when stream ends. If we just ignore
   // buffered data we will notify host that stream ended before it is actually
   // did so, I've seen it done ~140ms too early when playing ~150ms file.
   //
   // Instead of trying to invent OS-specific solution for each and every OS we
   // are supporting, use simple workaround: every time we fill the buffer we
   // remember when it should stop playing, and do not assume that buffer is
   // empty till that time. Workaround is not bulletproof, as we don't exactly
   // know when that particular data would start playing, but it is much better
   // than nothing.
+  // Access should be protected by lock as it can be accessed by pipeline and
+  // audio threads.
   base::Time earliest_end_time_;
 
   AudioParameters audio_parameters_;
 
+  // Use message loop proxy, not message loop itself, to avoid crash
+  // because of message loop that ended while we are still playing.
+  // We don't need complex shutdown operations, just not posting tasks
+  // is enough, so we can use message loop proxy.
+  scoped_refptr<base::MessageLoopProxy> pipeline_message_loop_proxy_;
+
+  // Cancellable closure called on end of stream.
+  // We may schedule the task but later cancel it on seek / pause.
+  base::CancelableClosure signal_end_of_stream_callback_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_