media/audio/audio_output_dispatcher_impl.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // AudioOutputDispatcherImpl is an implementation of AudioOutputDispatcher.
   6 //
   7 // To avoid opening and closing audio devices more frequently than necessary,
   8 // each dispatcher has a pool of inactive physical streams. A stream is closed
   9 // only if it hasn't been used for a certain period of time (specified via the
  10 // constructor).
  11 //
  12
  13 #ifndef MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_IMPL_H_
  14 #define MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_IMPL_H_
  15
  16 #include <list>
  17 #include <map>
  18
  19 #include "base/basictypes.h"
  20 #include "base/memory/ref_counted.h"
  21 #include "base/memory/weak_ptr.h"
  22 #include "base/timer/timer.h"
  23 #include "media/audio/audio_io.h"
  24 #include "media/audio/audio_manager.h"
  25 #include "media/audio/audio_output_dispatcher.h"
  26 #include "media/audio/audio_parameters.h"
  27
  28 namespace media {
  29
  30 class AudioOutputProxy;
  31
  32 class MEDIA_EXPORT AudioOutputDispatcherImpl : public AudioOutputDispatcher {
  33  public:
  34   // |close_delay_ms| specifies delay after the stream is paused until
  35   // the audio device is closed.
  36   AudioOutputDispatcherImpl(AudioManager* audio_manager,
  37                             const AudioParameters& params,
  38                             const std::string& input_device_id,
  39                             const base::TimeDelta& close_delay);
  40
  41   // Opens a new physical stream if there are no pending streams in
  42   // |idle_streams_|.  Do not call Close() or Stop() if this method fails.
  43   virtual bool OpenStream() OVERRIDE;
  44
  45   // If there are pending streams in |idle_streams_| then it reuses one of
  46   // them, otherwise creates a new one.
  47   virtual bool StartStream(AudioOutputStream::AudioSourceCallback* callback,
  48                            AudioOutputProxy* stream_proxy) OVERRIDE;
  49
  50   // Holds the physical stream temporarily in |pausing_streams_| and then
  51   // |stream| is  added to the pool of pending streams (i.e. |idle_streams_|).
  52   virtual void StopStream(AudioOutputProxy* stream_proxy) OVERRIDE;
  53
  54   virtual void StreamVolumeSet(AudioOutputProxy* stream_proxy,
  55                                double volume) OVERRIDE;
  56
  57   virtual void CloseStream(AudioOutputProxy* stream_proxy) OVERRIDE;
  58
  59   virtual void Shutdown() OVERRIDE;
  60
  61  private:
  62   typedef std::map<AudioOutputProxy*, AudioOutputStream*> AudioStreamMap;
  63   friend class base::RefCountedThreadSafe<AudioOutputDispatcherImpl>;
  64   virtual ~AudioOutputDispatcherImpl();
  65
  66   friend class AudioOutputProxyTest;
  67
  68   // Creates a new physical output stream, opens it and pushes to
  69   // |idle_streams_|.  Returns false if the stream couldn't be created or
  70   // opened.
  71   bool CreateAndOpenStream();
  72
  73   // A task scheduled by StartStream(). Opens a new stream and puts
  74   // it in |idle_streams_|.
  75   void OpenTask();
  76
  77   // Before a stream is reused, it should sit idle for a bit.  This task is
  78   // called once that time has elapsed.
  79   void StopStreamTask();
  80
  81   // Called by |close_timer_|. Closes all pending streams.
  82   void ClosePendingStreams();
  83
  84   base::TimeDelta pause_delay_;
  85   size_t paused_proxies_;
  86   typedef std::list<AudioOutputStream*> AudioOutputStreamList;
  87   AudioOutputStreamList idle_streams_;
  88   AudioOutputStreamList pausing_streams_;
  89
  90   // Used to post delayed tasks to ourselves that we cancel inside Shutdown().
  91   base::WeakPtrFactory<AudioOutputDispatcherImpl> weak_this_;
  92   base::DelayTimer<AudioOutputDispatcherImpl> close_timer_;
  93
  94   AudioStreamMap proxy_to_physical_map_;
  95
  96   DISALLOW_COPY_AND_ASSIGN(AudioOutputDispatcherImpl);
  97 };
  98
  99 }  // namespace media
 100
 101 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_IMPL_H_