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75 lines
2.7 KiB
75 lines
2.7 KiB
4 months ago
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// Copyright 2016 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TASK_SCHEDULER_TASK_H_
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#define BASE_TASK_SCHEDULER_TASK_H_
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#include "base/base_export.h"
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#include "base/callback.h"
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#include "base/location.h"
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#include "base/macros.h"
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#include "base/memory/ref_counted.h"
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#include "base/pending_task.h"
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#include "base/sequenced_task_runner.h"
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#include "base/single_thread_task_runner.h"
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#include "base/task_scheduler/task_traits.h"
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#include "base/time/time.h"
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namespace base {
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namespace internal {
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// A task is a unit of work inside the task scheduler. Support for tracing and
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// profiling inherited from PendingTask.
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struct BASE_EXPORT Task : public PendingTask {
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// |posted_from| is the site the task was posted from. |task| is the closure
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// to run. |traits_in| is metadata about the task. |delay| is a delay that
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// must expire before the Task runs. If |delay| is non-zero and the shutdown
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// behavior in |traits| is BLOCK_SHUTDOWN, the shutdown behavior is
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// automatically adjusted to SKIP_ON_SHUTDOWN.
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Task(const Location& posted_from,
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OnceClosure task,
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const TaskTraits& traits,
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TimeDelta delay);
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// Task is move-only to avoid mistakes that cause reference counts to be
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// accidentally bumped.
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Task(Task&& other) noexcept;
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~Task();
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Task& operator=(Task&& other);
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// The TaskTraits of this task.
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TaskTraits traits;
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// The delay that must expire before the task runs.
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TimeDelta delay;
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// The time at which the task was inserted in its sequence. For an undelayed
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// task, this happens at post time. For a delayed task, this happens some
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// time after the task's delay has expired. If the task hasn't been inserted
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// in a sequence yet, this defaults to a null TimeTicks.
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TimeTicks sequenced_time;
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// A reference to the SequencedTaskRunner or SingleThreadTaskRunner that
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// posted this task, if any. Used to set ThreadTaskRunnerHandle and/or
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// SequencedTaskRunnerHandle while the task is running.
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// Note: this creates an ownership cycle
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// Sequence -> Task -> TaskRunner -> Sequence -> ...
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// but that's okay as it's broken when the Task is popped from its Sequence
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// after being executed which means this cycle forces the TaskRunner to stick
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// around until all its tasks have been executed which is a requirement to
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// support TaskRunnerHandles.
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scoped_refptr<SequencedTaskRunner> sequenced_task_runner_ref;
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scoped_refptr<SingleThreadTaskRunner> single_thread_task_runner_ref;
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private:
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DISALLOW_COPY_AND_ASSIGN(Task);
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};
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} // namespace internal
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} // namespace base
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#endif // BASE_TASK_SCHEDULER_TASK_H_
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