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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.
#ifndef MEDIA_BASE_SERIAL_RUNNER_H_
#define MEDIA_BASE_SERIAL_RUNNER_H_
#include <memory>
#include "base/callback.h"
#include "base/containers/circular_deque.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "media/base/media_export.h"
#include "media/base/pipeline_status.h"
namespace base {
class SingleThreadTaskRunner;
}
namespace media {
// Runs a series of bound functions accepting Closures or
// PipelineStatusCallback. SerialRunner doesn't use regular
// OnceClosure/PipelineStatusCallbacks as it late binds the completion callback
// as the series progresses.
class MEDIA_EXPORT SerialRunner {
public:
typedef base::OnceCallback<void(base::OnceClosure)> BoundClosure;
typedef base::OnceCallback<void(PipelineStatusCallback)>
BoundPipelineStatusCallback;
// Serial queue of bound functions to run.
class MEDIA_EXPORT Queue {
public:
Queue();
Queue(Queue&& other);
~Queue();
void Push(base::OnceClosure closure);
void Push(BoundClosure bound_fn);
void Push(BoundPipelineStatusCallback bound_fn);
private:
Queue(const Queue&) = delete;
Queue& operator=(const Queue&) = delete;
friend class SerialRunner;
BoundPipelineStatusCallback Pop();
bool empty();
base::circular_deque<BoundPipelineStatusCallback> bound_fns_;
};
// Executes the bound functions in series, executing |done_cb| when finished.
//
// All bound functions are executed on the thread that Run() is called on,
// including |done_cb|.
//
// To eliminate an unnecessary posted task, the first function is executed
// immediately on the caller's stack. It is *strongly advised* to ensure
// the calling code does no more work after the call to Run().
//
// In all cases, |done_cb| is guaranteed to execute on a separate calling
// stack.
//
// Deleting the object will prevent execution of any unstarted bound
// functions, including |done_cb|.
static std::unique_ptr<SerialRunner> Run(Queue&& bound_fns,
PipelineStatusCallback done_cb);
private:
friend std::default_delete<SerialRunner>;
SerialRunner(Queue&& bound_fns, PipelineStatusCallback done_cb);
~SerialRunner();
void RunNextInSeries(PipelineStatus last_status);
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
Queue bound_fns_;
PipelineStatusCallback done_cb_;
// NOTE: Weak pointers must be invalidated before all other member variables.
base::WeakPtrFactory<SerialRunner> weak_factory_{this};
DISALLOW_COPY_AND_ASSIGN(SerialRunner);
};
} // namespace media
#endif // MEDIA_BASE_SERIAL_RUNNER_H_