Switch audio synchronization from sleep() based to select() based.

content/browser/renderer_host/media/audio_sync_reader.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_SYNC_READER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_SYNC_READER_H_
 
 #include "base/file_descriptor_posix.h"
 #include "base/process/process.h"
 #include "base/sync_socket.h"
@@ skipping 15 matching lines @@
 class AudioSyncReader : public media::AudioOutputController::SyncReader {
  public:
   AudioSyncReader(base::SharedMemory* shared_memory,
                   const media::AudioParameters& params,
                   int input_channels);
 
   virtual ~AudioSyncReader();
 
   // media::AudioOutputController::SyncReader implementations.
   virtual void UpdatePendingBytes(uint32 bytes) OVERRIDE;
+  // TODO(dalecurtis): Remove block.
   virtual int Read(bool block,
                    const media::AudioBus* source,
                    media::AudioBus* dest) OVERRIDE;
   virtual void Close() OVERRIDE;
 
   bool Init();
   bool PrepareForeignSocketHandle(base::ProcessHandle process_handle,
 #if defined(OS_WIN)
                                   base::SyncSocket::Handle* foreign_handle);
 #else
                                   base::FileDescriptor* foreign_handle);
 #endif
 
  private:
   // Indicates whether the renderer has data available for reading.
   bool DataReady();
 
-  // Blocks until DataReady() is true or a timeout expires.
-  void WaitTillDataReady();
+  // Blocks until DataReady() is true or a timeout expires.  Returns false if a
+  // timeout occurs.
+  bool WaitTillDataReady();
 
   base::SharedMemory* shared_memory_;
 
   // Number of input channels for synchronized I/O.
   int input_channels_;
 
   // Mutes all incoming samples. This is used to prevent audible sound
   // during automated testing.
   bool mute_audio_;
 
@@ skipping 11 matching lines @@
   scoped_ptr<media::AudioBus> input_bus_;
 
   // Maximum amount of audio data which can be transferred in one Read() call.
   int packet_size_;
 
   // Track the number of times the renderer missed its real-time deadline and
   // report a UMA stat during destruction.
   size_t renderer_callback_count_;
   size_t renderer_missed_callback_count_;
 
+  // The maximum amount of time to wait for data from the renderer.  Calculated
+  // from the parameters given at construction.
+  const base::TimeDelta maximum_wait_time_;
+
+  // The index of the audio buffer we're expecting to be sent from the renderer;
+  // used to block with timeout for audio data.
+  uint32_t buffer_index_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioSyncReader);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_SYNC_READER_H_