thread_pool.h | Explore in Territory

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_TASK_THREAD_POOL_H_
#define BASE_TASK_THREAD_POOL_H_

#include <memory>
#include <utility>

#include "base/base_export.h"
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/functional/callback_helpers.h"
#include "base/location.h"
#include "base/memory/scoped_refptr.h"
#include "base/task/post_task_and_reply_with_result_internal.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/single_thread_task_runner.h"
#include "base/task/single_thread_task_runner_thread_mode.h"
#include "base/task/task_runner.h"
#include "base/task/task_traits.h"
#include "base/task/updateable_sequenced_task_runner.h"
#include "base/time/time.h"
#include "build/build_config.h"

namespace base {

// This is the interface to post tasks to base's thread pool.
//
// To post a simple one-off task with default traits:
//     base::ThreadPool::PostTask(FROM_HERE, base::BindOnce(...));
//
// To post a high priority one-off task to respond to a user interaction:
//     base::ThreadPool::PostTask(
//         FROM_HERE,
//         {base::TaskPriority::USER_BLOCKING},
//         base::BindOnce(...));
//
// To post tasks that must run in sequence with default traits:
//     scoped_refptr<SequencedTaskRunner> task_runner =
//         base::ThreadPool::CreateSequencedTaskRunner();
//     task_runner->PostTask(FROM_HERE, base::BindOnce(...));
//     task_runner->PostTask(FROM_HERE, base::BindOnce(...));
//
// To post tasks that may block, must run in sequence and can be skipped on
// shutdown:
//     scoped_refptr<SequencedTaskRunner> task_runner =
//         base::ThreadPool::CreateSequencedTaskRunner(
//             {MayBlock(), TaskShutdownBehavior::SKIP_ON_SHUTDOWN});
//     task_runner->PostTask(FROM_HERE, base::BindOnce(...));
//     task_runner->PostTask(FROM_HERE, base::BindOnce(...));
//
// The default traits apply to tasks that:
//     (1) don't block (ref. MayBlock() and WithBaseSyncPrimitives()),
//     (2) prefer inheriting the current priority to specifying their own, and
//     (3) can either block shutdown or be skipped on shutdown
//         (implementation is free to choose a fitting default).
// Explicit traits must be specified for tasks for which these loose
// requirements are not sufficient.
//
// Prerequisite: A ThreadPoolInstance must have been registered for the current
// process via ThreadPoolInstance::Set() before the API below can be invoked.
// This is typically done during the initialization phase in each process. If
// your code is not running in that phase, you most likely don't have to worry
// about this. You will encounter DCHECKs or nullptr dereferences if this is
// violated. For tests, use base::test::TaskEnvironment.
class BASE_EXPORT ThreadPool { … };

}  // namespace base

#endif  // BASE_TASK_THREAD_POOL_H_
chromium/base/task/thread_pool.h
