audio_output_dispatcher_impl.h revision 868fa2fe829687343ffae624259930155e16dbd8 
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.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
28namespace media {
29
30class AudioOutputProxy;
31
32class 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_
102