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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.
#ifndef BASE_DEFERRED_SEQUENCED_TASKRUNNER_H_
#define BASE_DEFERRED_SEQUENCED_TASKRUNNER_H_
#include <vector>
#include "base/base_export.h"
#include "base/basictypes.h"
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/memory/ref_counted.h"
#include "base/sequenced_task_runner.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
#include "base/tracked_objects.h"
namespace base {
// A DeferredSequencedTaskRunner is a subclass of SequencedTaskRunner that
// queues up all requests until the first call to Start() is issued.
class BASE_EXPORT DeferredSequencedTaskRunner : public SequencedTaskRunner {
public:
explicit DeferredSequencedTaskRunner(
const scoped_refptr<SequencedTaskRunner>& target_runner);
// TaskRunner implementation
bool PostDelayedTask(const tracked_objects::Location& from_here,
const Closure& task,
TimeDelta delay) override;
bool RunsTasksOnCurrentThread() const override;
// SequencedTaskRunner implementation
bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
const Closure& task,
TimeDelta delay) override;
// Start the execution - posts all queued tasks to the target executor. The
// deferred tasks are posted with their initial delay, meaning that the task
// execution delay is actually measured from Start.
// Fails when called a second time.
void Start();
private:
struct DeferredTask {
DeferredTask();
~DeferredTask();
tracked_objects::Location posted_from;
Closure task;
// The delay this task was initially posted with.
TimeDelta delay;
bool is_non_nestable;
};
~DeferredSequencedTaskRunner() override;
// Creates a |Task| object and adds it to |deferred_tasks_queue_|.
void QueueDeferredTask(const tracked_objects::Location& from_here,
const Closure& task,
TimeDelta delay,
bool is_non_nestable);
// // Protects |started_| and |deferred_tasks_queue_|.
mutable Lock lock_;
bool started_;
const scoped_refptr<SequencedTaskRunner> target_task_runner_;
std::vector<DeferredTask> deferred_tasks_queue_;
DISALLOW_COPY_AND_ASSIGN(DeferredSequencedTaskRunner);
};
} // namespace base
#endif // BASE_DEFERRED_SEQUENCED_TASKRUNNER_H_
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