91 lines
3.9 KiB
C
91 lines
3.9 KiB
C
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// Copyright 2018 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_TASK_EXECUTOR_H_
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#define BASE_TASK_TASK_EXECUTOR_H_
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#include <stdint.h>
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#include "base/base_export.h"
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#include "base/memory/ref_counted.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/single_thread_task_runner_thread_mode.h"
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#include "base/task_runner.h"
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#include "build/build_config.h"
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namespace base {
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class Location;
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class TaskTraits;
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// A TaskExecutor can execute Tasks with a specific TaskTraits extension id. To
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// handle Tasks posted via the //base/task/post_task.h API, the TaskExecutor
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// should be registered by calling RegisterTaskExecutor().
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class BASE_EXPORT TaskExecutor {
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public:
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virtual ~TaskExecutor() = default;
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// Posts |task| with a |delay| and specific |traits|. |delay| can be zero. For
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// one off tasks that don't require a TaskRunner. Returns false if the task
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// definitely won't run because of current shutdown state.
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virtual bool PostDelayedTask(const Location& from_here,
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const TaskTraits& traits,
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OnceClosure task,
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TimeDelta delay) = 0;
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// Returns a TaskRunner whose PostTask invocations result in scheduling tasks
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// using |traits|. Tasks may run in any order and in parallel.
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virtual scoped_refptr<TaskRunner> CreateTaskRunner(
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const TaskTraits& traits) = 0;
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// Returns a SequencedTaskRunner whose PostTask invocations result in
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// scheduling tasks using |traits|. Tasks run one at a time in posting order.
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virtual scoped_refptr<SequencedTaskRunner> CreateSequencedTaskRunner(
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const TaskTraits& traits) = 0;
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// Returns a SingleThreadTaskRunner whose PostTask invocations result in
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// scheduling tasks using |traits|. Tasks run on a single thread in posting
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// order. If |traits| identifies an existing thread,
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// SingleThreadTaskRunnerThreadMode::SHARED must be used.
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virtual scoped_refptr<SingleThreadTaskRunner> CreateSingleThreadTaskRunner(
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const TaskTraits& traits,
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SingleThreadTaskRunnerThreadMode thread_mode) = 0;
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#if defined(OS_WIN)
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// Returns a SingleThreadTaskRunner whose PostTask invocations result in
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// scheduling tasks using |traits| in a COM Single-Threaded Apartment. Tasks
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// run in the same Single-Threaded Apartment in posting order for the returned
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// SingleThreadTaskRunner. If |traits| identifies an existing thread,
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// SingleThreadTaskRunnerThreadMode::SHARED must be used.
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virtual scoped_refptr<SingleThreadTaskRunner> CreateCOMSTATaskRunner(
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const TaskTraits& traits,
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SingleThreadTaskRunnerThreadMode thread_mode) = 0;
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#endif // defined(OS_WIN)
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};
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// Register a TaskExecutor with the //base/task/post_task.h API in the current
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// process for tasks subsequently posted with a TaskTraits extension with the
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// given |extension_id|. All executors need to be registered before any tasks
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// are posted with |extension_id|. Only one executor per |extension_id| is
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// supported.
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void BASE_EXPORT RegisterTaskExecutor(uint8_t extension_id,
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TaskExecutor* task_executor);
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void BASE_EXPORT UnregisterTaskExecutorForTesting(uint8_t extension_id);
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// Stores the provided TaskExecutor in TLS for the current thread, to be used by
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// tasks with the CurrentThread() trait.
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void BASE_EXPORT SetTaskExecutorForCurrentThread(TaskExecutor* task_executor);
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// Returns the task executor registered for the current thread.
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BASE_EXPORT TaskExecutor* GetTaskExecutorForCurrentThread();
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// Determines whether a registered TaskExecutor will handle tasks with the given
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// |traits| and, if so, returns a pointer to it. Otherwise, returns |nullptr|.
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TaskExecutor* GetRegisteredTaskExecutorForTraits(const TaskTraits& traits);
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} // namespace base
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#endif // BASE_TASK_TASK_EXECUTOR_H_
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