base/message_loop/message_loop_proxy.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_MESSAGE_LOOP_MESSAGE_LOOP_PROXY_H_
   6 #define BASE_MESSAGE_LOOP_MESSAGE_LOOP_PROXY_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/compiler_specific.h"
  10 #include "base/memory/ref_counted.h"
  11 #include "base/single_thread_task_runner.h"
  12
  13 // MessageLoopProxy is deprecated. Code should prefer to depend on TaskRunner
  14 // (or the various specializations) for passing task runners around, and should
  15 // use ThreadTaskRunnerHandle::Get() to get the thread's associated task runner.
  16 //
  17 // See http://crbug.com/391045 for more details.
  18 // Example for these changes:
  19 //
  20 // base::MessageLoopProxy::current() -> base::ThreadTaskRunnerHandle::Get()
  21 // scoped_refptr<base::MessageLoopProxy> ->
  22 //     scoped_refptr<base::SingleThreadTaskRunner>
  23 // base::MessageLoopProxy -> base::SingleThreadTaskRunner
  24
  25 namespace base {
  26
  27 // This class provides a thread-safe refcounted interface to the Post* methods
  28 // of a message loop. This class can outlive the target message loop.
  29 // MessageLoopProxy objects are constructed automatically for all MessageLoops.
  30 // So, to access them, you can use any of the following:
  31 //   Thread::message_loop_proxy()
  32 //   MessageLoop::current()->message_loop_proxy()
  33 //   MessageLoopProxy::current()
  34 //
  35 // TODO(akalin): Now that we have the *TaskRunner interfaces, we can
  36 // merge this with MessageLoopProxyImpl.
  37 class BASE_EXPORT MessageLoopProxy : public SingleThreadTaskRunner {
  38  public:
  39   // Gets the MessageLoopProxy for the current message loop, creating one if
  40   // needed.
  41   static scoped_refptr<MessageLoopProxy> current();
  42
  43  protected:
  44   MessageLoopProxy();
  45   ~MessageLoopProxy() override;
  46 };
  47
  48 }  // namespace base
  49
  50 #endif  // BASE_MESSAGE_LOOP_MESSAGE_LOOP_PROXY_H_