single_thread_task_runner.h

// Copyright (c) 2012 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_SINGLE_THREAD_TASK_RUNNER_H_
#define BASE_TASK_SINGLE_THREAD_TASK_RUNNER_H_

#include "base/base_export.h"
#include "base/task/sequenced_task_runner.h"

namespace base {

// A SingleThreadTaskRunner is a SequencedTaskRunner with one more
// guarantee; namely, that all tasks are run on a single dedicated
// thread.  Most use cases require only a SequencedTaskRunner, unless
// there is a specific need to run tasks on only a single thread.
//
// SingleThreadTaskRunner implementations might:
//   - Post tasks to an existing thread's MessageLoop (see
//     MessageLoop::task_runner()).
//   - Create their own worker thread and MessageLoop to post tasks to.
//   - Add tasks to a FIFO and signal to a non-MessageLoop thread for them to
//     be processed. This allows TaskRunner-oriented code run on threads
//     running other kinds of message loop, e.g. Jingle threads.
class BASE_EXPORT SingleThreadTaskRunner : public SequencedTaskRunner {
 public:
  // A more explicit alias to RunsTasksInCurrentSequence().
  bool BelongsToCurrentThread() const { return RunsTasksInCurrentSequence(); }

 protected:
  ~SingleThreadTaskRunner() override = default;
};

}  // namespace base

#endif  // BASE_TASK_SINGLE_THREAD_TASK_RUNNER_H_