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 #include "media/audio/scoped_task_runner_observer.h"
6
7 #include "base/bind.h"
8 #include "base/synchronization/waitable_event.h"
9
10 namespace media {
11
ScopedTaskRunnerObserver(const scoped_refptr<base::SingleThreadTaskRunner> & task_runner)12 ScopedTaskRunnerObserver::ScopedTaskRunnerObserver(
13 const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
14 : task_runner_(task_runner) {
15 ObserveLoopDestruction(true, NULL);
16 }
17
~ScopedTaskRunnerObserver()18 ScopedTaskRunnerObserver::~ScopedTaskRunnerObserver() {
19 ObserveLoopDestruction(false, NULL);
20 }
21
ObserveLoopDestruction(bool enable,base::WaitableEvent * done)22 void ScopedTaskRunnerObserver::ObserveLoopDestruction(
23 bool enable,
24 base::WaitableEvent* done) {
25 // Note: |done| may be NULL.
26 if (task_runner_->BelongsToCurrentThread()) {
27 base::MessageLoop* loop = base::MessageLoop::current();
28 if (enable) {
29 loop->AddDestructionObserver(this);
30 } else {
31 loop->RemoveDestructionObserver(this);
32 }
33 } else {
34 base::WaitableEvent event(false, false);
35 if (task_runner_->PostTask(FROM_HERE,
36 base::Bind(&ScopedTaskRunnerObserver::ObserveLoopDestruction,
37 base::Unretained(this), enable, &event))) {
38 event.Wait();
39 } else {
40 // The message loop's thread has already terminated, so no need to wait.
41 }
42 }
43
44 if (done)
45 done->Signal();
46 }
47
48 } // namespace media.
49