content/browser/renderer_host/media/audio_output_device_enumerator.h

   1 // Copyright (c) 2015 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 // AudioOutputDeviceEnumerator is used to enumerate audio output devices.
   6 // It can return cached results of previous enumerations in order to boost
   7 // performance.
   8 // All its public methods must be called on the thread where the object is
   9 // created.
  10
  11 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DEVICE_ENUMERATOR_H_
  12 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DEVICE_ENUMERATOR_H_
  13
  14 #include <stdint.h>
  15 #include <list>
  16 #include <string>
  17 #include <vector>
  18
  19 #include "base/callback.h"
  20 #include "base/macros.h"
  21 #include "base/memory/scoped_ptr.h"
  22 #include "base/memory/weak_ptr.h"
  23 #include "base/threading/thread_checker.h"
  24 #include "content/common/content_export.h"
  25 #include "media/audio/audio_parameters.h"
  26
  27 namespace base {
  28 class SingleThreadTaskRunner;
  29 }
  30
  31 namespace media {
  32 class AudioManager;
  33 }
  34
  35 namespace content {
  36
  37 // AudioOutputDeviceInfo describes information about an audio output device.
  38 // The enumerations returned by AudioOutputDeviceEnumerator::Enumerate() contain
  39 // elements of this type. It is used only in the browser side.
  40 struct AudioOutputDeviceInfo {
  41   std::string unique_id;
  42   std::string device_name;
  43   media::AudioParameters output_params;
  44 };
  45
  46 typedef std::vector<AudioOutputDeviceInfo> AudioOutputDeviceEnumeration;
  47 typedef base::Callback<void(const AudioOutputDeviceEnumeration&)>
  48     AudioOutputDeviceEnumerationCB;
  49
  50 class CONTENT_EXPORT AudioOutputDeviceEnumerator {
  51  public:
  52   enum CachePolicy {
  53     CACHE_POLICY_NO_CACHING,
  54     CACHE_POLICY_MANUAL_INVALIDATION
  55   };
  56   AudioOutputDeviceEnumerator(media::AudioManager* audio_manager,
  57                               CachePolicy cache_policy);
  58   ~AudioOutputDeviceEnumerator();
  59
  60   // Must be called on the IO thread. |callback| is also invoked
  61   // on the IO thread.
  62   void Enumerate(const AudioOutputDeviceEnumerationCB& callback);
  63
  64   // Invalidates the current cache. Must be called on the IO thread.
  65   void InvalidateCache();
  66
  67   // Sets the cache policy. Must be called on the IO thread.
  68   void SetCachePolicy(CachePolicy cache_policy);
  69
  70  private:
  71   void InitializeOnIOThread();
  72   void DoEnumerateDevices();
  73   AudioOutputDeviceEnumeration DoEnumerateDevicesOnDeviceThread();
  74   void DevicesEnumerated(const AudioOutputDeviceEnumeration& snapshot);
  75   int64_t NewEventSequence();
  76   bool IsLastEnumerationValid() const;
  77
  78   media::AudioManager* const audio_manager_;
  79   CachePolicy cache_policy_;
  80   AudioOutputDeviceEnumeration cache_;
  81   std::list<AudioOutputDeviceEnumerationCB> pending_callbacks_;
  82
  83   // sequential number that serves as logical clock
  84   int64_t current_event_sequence_;
  85
  86   int64_t seq_last_enumeration_;
  87   int64_t seq_last_invalidation_;
  88   bool is_enumeration_ongoing_;
  89
  90   base::ThreadChecker thread_checker_;
  91   base::WeakPtrFactory<AudioOutputDeviceEnumerator> weak_factory_;
  92
  93   DISALLOW_COPY_AND_ASSIGN(AudioOutputDeviceEnumerator);
  94 };
  95
  96 }  // namespace content
  97
  98 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DEVICE_ENUMERATOR_H_