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// Copyright (c) 2013 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 "media/base/fake_audio_worker.h"
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/cancelable_callback.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/single_thread_task_runner.h"
#include "base/synchronization/lock.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
#include "media/base/audio_parameters.h"
namespace media {
class FakeAudioWorker::Worker
: public base::RefCountedThreadSafe<FakeAudioWorker::Worker> {
public:
Worker(const scoped_refptr<base::SingleThreadTaskRunner>& worker_task_runner,
const AudioParameters& params);
bool IsStopped();
void Start(const base::Closure& worker_cb);
void Stop();
private:
friend class base::RefCountedThreadSafe<Worker>;
~Worker();
// Initialize and start regular calls to DoRead() on the worker thread.
void DoStart();
// Cancel any delayed callbacks to DoRead() in the worker loop's queue.
void DoCancel();
// Task that regularly calls |worker_cb_| according to the playback rate as
// determined by the audio parameters given during construction. Runs on
// the worker loop.
void DoRead();
const scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner_;
const base::TimeDelta buffer_duration_;
base::Lock worker_cb_lock_; // Held while mutating or running |worker_cb_|.
base::Closure worker_cb_;
base::TimeTicks next_read_time_;
// Used to cancel any delayed tasks still inside the worker loop's queue.
base::CancelableClosure worker_task_cb_;
THREAD_CHECKER(thread_checker_);
DISALLOW_COPY_AND_ASSIGN(Worker);
};
FakeAudioWorker::FakeAudioWorker(
const scoped_refptr<base::SingleThreadTaskRunner>& worker_task_runner,
const AudioParameters& params)
: worker_(new Worker(worker_task_runner, params)) {}
FakeAudioWorker::~FakeAudioWorker() {
DCHECK(worker_->IsStopped());
}
void FakeAudioWorker::Start(const base::Closure& worker_cb) {
DCHECK(worker_->IsStopped());
worker_->Start(worker_cb);
}
void FakeAudioWorker::Stop() {
worker_->Stop();
}
FakeAudioWorker::Worker::Worker(
const scoped_refptr<base::SingleThreadTaskRunner>& worker_task_runner,
const AudioParameters& params)
: worker_task_runner_(worker_task_runner),
buffer_duration_(base::TimeDelta::FromMicroseconds(
params.frames_per_buffer() * base::Time::kMicrosecondsPerSecond /
static_cast<float>(params.sample_rate()))) {
// Worker can be constructed on any thread, but will DCHECK that its
// Start/Stop methods are called from the same thread.
DETACH_FROM_THREAD(thread_checker_);
}
FakeAudioWorker::Worker::~Worker() {
DCHECK(!worker_cb_);
}
bool FakeAudioWorker::Worker::IsStopped() {
base::AutoLock scoped_lock(worker_cb_lock_);
return !worker_cb_;
}
void FakeAudioWorker::Worker::Start(const base::Closure& worker_cb) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
DCHECK(worker_cb);
{
base::AutoLock scoped_lock(worker_cb_lock_);
DCHECK(!worker_cb_);
worker_cb_ = worker_cb;
}
worker_task_runner_->PostTask(FROM_HERE,
base::BindOnce(&Worker::DoStart, this));
}
void FakeAudioWorker::Worker::DoStart() {
DCHECK(worker_task_runner_->BelongsToCurrentThread());
next_read_time_ = base::TimeTicks::Now();
worker_task_cb_.Reset(base::Bind(&Worker::DoRead, this));
worker_task_cb_.callback().Run();
}
void FakeAudioWorker::Worker::Stop() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
{
base::AutoLock scoped_lock(worker_cb_lock_);
if (!worker_cb_)
return;
worker_cb_.Reset();
}
worker_task_runner_->PostTask(FROM_HERE,
base::BindOnce(&Worker::DoCancel, this));
}
void FakeAudioWorker::Worker::DoCancel() {
DCHECK(worker_task_runner_->BelongsToCurrentThread());
worker_task_cb_.Cancel();
}
void FakeAudioWorker::Worker::DoRead() {
DCHECK(worker_task_runner_->BelongsToCurrentThread());
{
base::AutoLock scoped_lock(worker_cb_lock_);
if (worker_cb_)
worker_cb_.Run();
}
// Need to account for time spent here due to the cost of |worker_cb| as well
// as the imprecision of PostDelayedTask().
const base::TimeTicks now = base::TimeTicks::Now();
base::TimeDelta delay = next_read_time_ + buffer_duration_ - now;
// If we're behind, find the next nearest ontime interval.
if (delay < base::TimeDelta())
delay += buffer_duration_ * (-delay / buffer_duration_ + 1);
next_read_time_ = now + delay;
worker_task_runner_->PostDelayedTask(FROM_HERE, worker_task_cb_.callback(),
delay);
}
} // namespace media
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