Remove locking from FFmpegDemuxerStream and associated TODOs from media code.

media/filters/ffmpeg_demuxer.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.
 
 // Implements the Demuxer interface using FFmpeg's libavformat.  At this time
 // will support demuxing any audio/video format thrown at it.  The streams
 // output mime types audio/x-ffmpeg and video/x-ffmpeg and include an integer
 // key FFmpegCodecID which contains the CodecID enumeration value.  The CodecIDs
 // can be used to create and initialize the corresponding FFmpeg decoder.
 //
@@ skipping 38 matching lines @@
 
 typedef scoped_ptr_malloc<AVPacket, ScopedPtrAVFreePacket> ScopedAVPacket;
 
 class FFmpegDemuxerStream : public DemuxerStream {
  public:
   // Keeps a copy of |demuxer| and initializes itself using information
   // inside |stream|.  Both parameters must outlive |this|.
   FFmpegDemuxerStream(FFmpegDemuxer* demuxer, AVStream* stream);
 
   // Returns true is this stream has pending reads, false otherwise.
-  //
-  // Safe to call on any thread.
   bool HasPendingReads();
 
   // Enqueues the given AVPacket.  If |packet| is NULL an end of stream packet
   // is enqueued.
   void EnqueuePacket(ScopedAVPacket packet);
 
   // Signals to empty the buffer queue and mark next packet as discontinuous.
   void FlushBuffers();
 
   // Empties the queues and ignores any additional calls to Read().
   void Stop();
 
   // Returns the duration of this stream.
   base::TimeDelta duration();
 
   // DemuxerStream implementation.
   virtual Type type() OVERRIDE;
-
-  // If |buffer_queue_| is not empty will execute on caller's thread, otherwise
-  // will post ReadTask to execute on demuxer's thread. Read will acquire
-  // |lock_| for the life of the function so that means |read_cb| must
-  // not make calls into FFmpegDemuxerStream directly or that may cause a
-  // deadlock. |read_cb| should execute as quickly as possible because
-  // |lock_| is held throughout the life of the callback.
   virtual void Read(const ReadCB& read_cb) OVERRIDE;
   virtual void EnableBitstreamConverter() OVERRIDE;
   virtual const AudioDecoderConfig& audio_decoder_config() OVERRIDE;
   virtual const VideoDecoderConfig& video_decoder_config() OVERRIDE;
 
   // Returns the range of buffered data in this stream.
   Ranges<base::TimeDelta> GetBufferedRanges() const;
 
   // Returns elapsed time based on the already queued packets.
   // Used to determine stream duration when it's not known ahead of time.
   base::TimeDelta GetElapsedTime() const;
 
  protected:
   virtual ~FFmpegDemuxerStream();
 
  private:
   friend class FFmpegDemuxerTest;
 
-  // Carries out enqueuing a pending read on the demuxer thread.
-  void ReadTask(const ReadCB& read_cb);
-
-  // Attempts to fulfill a single pending read by dequeueing a buffer and read
-  // callback pair and executing the callback. The calling function must
-  // acquire |lock_| before calling this function.
-  void FulfillPendingRead();
+  // Runs callbacks in |read_queue_| for each available |buffer_queue_|, calling
+  // NotifyHasPendingRead() if there are still pending items in |read_queue_|.
+  void SatisfyPendingReads();
 
   // Converts an FFmpeg stream timestamp into a base::TimeDelta.
   static base::TimeDelta ConvertStreamTimestamp(const AVRational& time_base,
                                                 int64 timestamp);
 
   FFmpegDemuxer* demuxer_;
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
   AVStream* stream_;
   AudioDecoderConfig audio_config_;
   VideoDecoderConfig video_config_;
   Type type_;
   base::TimeDelta duration_;
   bool stopped_;
   base::TimeDelta last_packet_timestamp_;
   Ranges<base::TimeDelta> buffered_ranges_;
 
   typedef std::deque<scoped_refptr<DecoderBuffer> > BufferQueue;
   BufferQueue buffer_queue_;
 
   typedef std::deque<ReadCB> ReadQueue;
   ReadQueue read_queue_;
 
   scoped_ptr<FFmpegH264ToAnnexBBitstreamConverter> bitstream_converter_;
   bool bitstream_converter_enabled_;
 
-  // Used to synchronize access to |buffer_queue_|, |read_queue_|, and
-  // |stopped_|. This is so other threads can get access to buffers that have
-  // already been demuxed without having the demuxer thread sending the
-  // buffers. |lock_| must be acquired before any access to |buffer_queue_|,
-  // |read_queue_|, or |stopped_|.
-  mutable base::Lock lock_;
-
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxerStream);
 };
 
 class MEDIA_EXPORT FFmpegDemuxer : public Demuxer {
  public:
   FFmpegDemuxer(const scoped_refptr<base::MessageLoopProxy>& message_loop,
                 const scoped_refptr<DataSource>& data_source);
 
-  // Posts a task to perform additional demuxing.
-  virtual void PostDemuxTask();
-
   // Demuxer implementation.
   virtual void Initialize(DemuxerHost* host,
                           const PipelineStatusCB& status_cb) OVERRIDE;
   virtual void Stop(const base::Closure& callback) OVERRIDE;
   virtual void Seek(base::TimeDelta time, const PipelineStatusCB& cb) OVERRIDE;
   virtual void OnAudioRendererDisabled() OVERRIDE;
   virtual void SetPlaybackRate(float playback_rate) OVERRIDE;
   virtual scoped_refptr<DemuxerStream> GetStream(
       DemuxerStream::Type type) OVERRIDE;
   virtual base::TimeDelta GetStartTime() const OVERRIDE;
 
-  // Provide access to FFmpegDemuxerStream.
-  scoped_refptr<base::MessageLoopProxy> message_loop();
-
-  // Allow FFmpegDemuxerStream to notify us when there is updated information
-  // about what buffered data is available.
+  // Allow FFmpegDemuxerStream to notify us when it requires more data or has
+  // updated information about what buffered data is available.
+  void NotifyHasPendingRead();
   void NotifyBufferingChanged();
 
  private:
   // To allow tests access to privates.
   friend class FFmpegDemuxerTest;
 
   virtual ~FFmpegDemuxer();
 
   // Carries out initialization on the demuxer thread.
   void InitializeTask(DemuxerHost* host, const PipelineStatusCB& status_cb);
@@ skipping 77 matching lines @@
   // FFmpegURLProtocol implementation and corresponding glue bits.
   BlockingUrlProtocol url_protocol_;
   scoped_ptr<FFmpegGlue> glue_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_DEMUXER_H_