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// Copyright 2016 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_TASK_SCHEDULER_TASK_H_
#define BASE_TASK_SCHEDULER_TASK_H_
#include "base/base_export.h"
#include "base/callback.h"
#include "base/location.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/pending_task.h"
#include "base/sequenced_task_runner.h"
#include "base/single_thread_task_runner.h"
#include "base/task_scheduler/task_traits.h"
#include "base/time/time.h"
namespace base {
namespace internal {
// A task is a unit of work inside the task scheduler. Support for tracing and
// profiling inherited from PendingTask.
struct BASE_EXPORT Task : public PendingTask {
// |posted_from| is the site the task was posted from. |task| is the closure
// to run. |traits_in| is metadata about the task. |delay| is a delay that
// must expire before the Task runs. If |delay| is non-zero and the shutdown
// behavior in |traits| is BLOCK_SHUTDOWN, the shutdown behavior is
// automatically adjusted to SKIP_ON_SHUTDOWN.
Task(const tracked_objects::Location& posted_from,
OnceClosure task,
const TaskTraits& traits,
TimeDelta delay);
~Task();
// The TaskTraits of this task.
const TaskTraits traits;
// The delay that must expire before the task runs.
const TimeDelta delay;
// The time at which the task was inserted in its sequence. For an undelayed
// task, this happens at post time. For a delayed task, this happens some
// time after the task's delay has expired. If the task hasn't been inserted
// in a sequence yet, this defaults to a null TimeTicks.
TimeTicks sequenced_time;
// A reference to the SequencedTaskRunner or SingleThreadTaskRunner that
// posted this task, if any. Used to set ThreadTaskRunnerHandle and/or
// SequencedTaskRunnerHandle while the task is running.
// Note: this creates an ownership cycle
// Sequence -> Task -> TaskRunner -> Sequence -> ...
// but that's okay as it's broken when the Task is popped from its Sequence
// after being executed which means this cycle forces the TaskRunner to stick
// around until all its tasks have been executed which is a requirement to
// support TaskRunnerHandles.
scoped_refptr<SequencedTaskRunner> sequenced_task_runner_ref;
scoped_refptr<SingleThreadTaskRunner> single_thread_task_runner_ref;
private:
// Disallow copies to make sure no unnecessary ref-bumps are incurred. Making
// it move-only would be an option, but isn't necessary for now.
DISALLOW_COPY_AND_ASSIGN(Task);
};
} // namespace internal
} // namespace base
#endif // BASE_TASK_SCHEDULER_TASK_H_
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