base/single_thread_task_runner.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_SINGLE_THREAD_TASK_RUNNER_H_
   6 #define BASE_SINGLE_THREAD_TASK_RUNNER_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/sequenced_task_runner.h"
  10
  11 namespace base {
  12
  13 // A SingleThreadTaskRunner is a SequencedTaskRunner with one more
  14 // guarantee; namely, that all tasks are run on a single dedicated
  15 // thread.  Most use cases require only a SequencedTaskRunner, unless
  16 // there is a specific need to run tasks on only a single thread.
  17 //
  18 // SingleThreadTaskRunner implementations might:
  19 //   - Post tasks to an existing thread's MessageLoop (see
  20 //     MessageLoop::task_runner()).
  21 //   - Create their own worker thread and MessageLoop to post tasks to.
  22 //   - Add tasks to a FIFO and signal to a non-MessageLoop thread for them to
  23 //     be processed. This allows TaskRunner-oriented code run on threads
  24 //     running other kinds of message loop, e.g. Jingle threads.
  25 class BASE_EXPORT SingleThreadTaskRunner : public SequencedTaskRunner {
  26  public:
  27   // A more explicit alias to RunsTasksOnCurrentThread().
  28   bool BelongsToCurrentThread() const {
  29     return RunsTasksOnCurrentThread();
  30   }
  31
  32  protected:
  33   ~SingleThreadTaskRunner() override {}
  34 };
  35
  36 }  // namespace base
  37
  38 #endif  // BASE_SINGLE_THREAD_TASK_RUNNER_H_