// Copyright (c) 2011 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_
#pragma once

#include "base/file_descriptor_posix.h"
#include "base/process.h"
#include "base/sync_socket.h"
#include "base/synchronization/lock.h"
#include "base/time.h"
#include "media/audio/audio_output_controller.h"

namespace base {
class SharedMemory;
}

// A AudioOutputController::SyncReader implementation using SyncSocket. This
// is used by AudioOutputController to provide a low latency data source for
// transmitting audio packets between the browser process and the renderer
// process.
class AudioSyncReader : public media::AudioOutputController::SyncReader {
 public:
  explicit AudioSyncReader(base::SharedMemory* shared_memory);

  virtual ~AudioSyncReader();

  // media::AudioOutputController::SyncReader implementations.
  virtual void UpdatePendingBytes(uint32 bytes) OVERRIDE;
  virtual uint32 Read(void* data, uint32 size) OVERRIDE;
  virtual void Close() OVERRIDE;
  virtual bool DataReady() 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:
  base::SharedMemory* shared_memory_;
  base::Time previous_call_time_;

  // A pair of SyncSocket for transmitting audio data.
  scoped_ptr<base::SyncSocket> socket_;

  // SyncSocket to be used by the renderer. The reference is released after
  // PrepareForeignSocketHandle() is called and ran successfully.
  scoped_ptr<base::SyncSocket> foreign_socket_;

  // Protect socket_ access by lock to prevent race condition when audio
  // controller thread closes the reader and hardware audio thread is reading
  // data. This way we know that socket would not be deleted while we are
  // writing data to it.
  base::Lock lock_;

  DISALLOW_COPY_AND_ASSIGN(AudioSyncReader);
};

#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_SYNC_READER_H_