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      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_
     93