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// 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.
#include <stdint.h>
#include "base/macros.h"
#include "base/memory/shared_memory.h"
#include "base/sync_socket.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_checker.h"
#include "media/base/audio_parameters.h"
#include "media/base/media_export.h"
namespace media {
// Data transfer between browser and render process uses a combination
// of sync sockets and shared memory. To read from the socket and render
// data, we use a worker thread, a.k.a. the AudioDeviceThread, which reads
// data from the browser via the socket and fills the shared memory from the
// audio thread via the AudioDeviceThread::Callback interface/class.
class MEDIA_EXPORT AudioDeviceThread : public base::PlatformThread::Delegate {
// This is the callback interface/base class that Audio[Output|Input]Device
// implements to render input/output data. The callbacks run on the
// thread owned by AudioDeviceThread.
class Callback {
Callback(const AudioParameters& audio_parameters,
uint32_t segment_length,
uint32_t total_segments);
// One time initialization for the callback object on the audio thread.
void InitializeOnAudioThread();
// Derived implementations must map shared memory appropriately before
// Process can be called.
virtual void MapSharedMemory() = 0;
// Called whenever we receive notifications about pending input data.
virtual void Process(uint32_t pending_data) = 0;
virtual ~Callback();
// Protected so that derived classes can access directly.
// The variables are 'const' since values are calculated/set in the
// constructor and must never change.
const AudioParameters audio_parameters_;
const uint32_t memory_length_;
const uint32_t total_segments_;
const uint32_t segment_length_;
// Detached in constructor and attached in InitializeOnAudioThread() which
// is called on the audio device thread. Sub-classes can then use it for
// various thread checking purposes.
base::ThreadChecker thread_checker_;
// Creates and automatically starts the audio thread.
AudioDeviceThread(Callback* callback,
base::SyncSocket::Handle socket,
const char* thread_name,
base::ThreadPriority thread_priority);
// This tells the audio thread to stop and clean up the data; this is a
// synchronous process and the thread will stop before the method returns.
// Blocking call, see base/threading/thread_restrictions.h.
~AudioDeviceThread() override;
void ThreadMain() final;
Callback* const callback_;
const char* thread_name_;
base::CancelableSyncSocket socket_;
base::PlatformThreadHandle thread_handle_;
} // namespace media.