base/thread_task_runner_handle.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_THREAD_TASK_RUNNER_HANDLE_H_
   6 #define BASE_THREAD_TASK_RUNNER_HANDLE_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/memory/ref_counted.h"
  10
  11 namespace base {
  12
  13 class SingleThreadTaskRunner;
  14
  15 // ThreadTaskRunnerHandle stores a reference to a thread's TaskRunner
  16 // in thread-local storage.  Callers can then retrieve the TaskRunner
  17 // for the current thread by calling ThreadTaskRunnerHandle::Get().
  18 // At most one TaskRunner may be bound to each thread at a time.
  19 class BASE_EXPORT ThreadTaskRunnerHandle {
  20  public:
  21   // Gets the SingleThreadTaskRunner for the current thread.
  22   static scoped_refptr<SingleThreadTaskRunner> Get();
  23
  24   // Returns true if the SingleThreadTaskRunner is already created for
  25   // the current thread.
  26   static bool IsSet();
  27
  28   // Binds |task_runner| to the current thread. |task_runner| must belong
  29   // to the current thread for this to succeed.
  30   explicit ThreadTaskRunnerHandle(
  31       const scoped_refptr<SingleThreadTaskRunner>& task_runner);
  32   ~ThreadTaskRunnerHandle();
  33
  34  private:
  35   scoped_refptr<SingleThreadTaskRunner> task_runner_;
  36 };
  37
  38 }  // namespace base
  39
  40 #endif  // BASE_THREAD_TASK_RUNNER_HANDLE_H_