remoting/host/linux/audio_pipe_reader.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 #ifndef REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_
   6 #define REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "base/memory/ref_counted_memory.h"
  10 #include "base/message_loop/message_loop.h"
  11 #include "base/observer_list_threadsafe.h"
  12 #include "base/time/time.h"
  13 #include "base/timer/timer.h"
  14
  15 namespace base {
  16 class FilePath;
  17 }
  18
  19 namespace remoting {
  20
  21 struct AudioPipeReaderTraits;
  22
  23 // AudioPipeReader class reads from a named pipe to which an audio server (e.g.
  24 // pulseaudio) writes the sound that's being played back and then sends data to
  25 // all registered observers.
  26 class AudioPipeReader
  27   : public base::RefCountedThreadSafe<AudioPipeReader, AudioPipeReaderTraits>,
  28       public base::MessageLoopForIO::Watcher {
  29  public:
  30   class StreamObserver {
  31    public:
  32     virtual void OnDataRead(scoped_refptr<base::RefCountedString> data) = 0;
  33   };
  34
  35   // |task_runner| specifies the IO thread to use to read data from the pipe.
  36   static scoped_refptr<AudioPipeReader> Create(
  37       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
  38       const base::FilePath& pipe_name);
  39
  40   // Register or unregister an observer. Each observer receives data on the
  41   // thread on which it was registered and guaranteed not to be called after
  42   // RemoveObserver().
  43   void AddObserver(StreamObserver* observer);
  44   void RemoveObserver(StreamObserver* observer);
  45
  46   // MessageLoopForIO::Watcher interface.
  47   virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
  48   virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
  49
  50  private:
  51   friend class base::DeleteHelper<AudioPipeReader>;
  52   friend class base::RefCountedThreadSafe<AudioPipeReader>;
  53   friend struct AudioPipeReaderTraits;
  54
  55   AudioPipeReader(scoped_refptr<base::SingleThreadTaskRunner> task_runner);
  56   virtual ~AudioPipeReader();
  57
  58   void StartOnAudioThread(const base::FilePath& pipe_name);
  59   void StartTimer();
  60   void DoCapture();
  61   void WaitForPipeReadable();
  62
  63   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  64
  65   int pipe_fd_;
  66   base::RepeatingTimer<AudioPipeReader> timer_;
  67   scoped_refptr<ObserverListThreadSafe<StreamObserver> > observers_;
  68
  69   // Time when capturing was started.
  70   base::TimeTicks started_time_;
  71
  72   // Stream position of the last capture in bytes with zero position
  73   // corresponding to |started_time_|. Must always be a multiple of the sample
  74   // size.
  75   int64 last_capture_position_;
  76
  77   // Bytes left from the previous read.
  78   std::string left_over_bytes_;
  79
  80   base::MessageLoopForIO::FileDescriptorWatcher file_descriptor_watcher_;
  81
  82   DISALLOW_COPY_AND_ASSIGN(AudioPipeReader);
  83 };
  84
  85 // Destroys |audio_pipe_reader| on the audio thread.
  86 struct AudioPipeReaderTraits {
  87   static void Destruct(const AudioPipeReader* audio_pipe_reader);
  88 };
  89
  90 }  // namespace remoting
  91
  92 #endif  // REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_