1 // Copyright 2013 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 "extensions/common/one_shot_event.h"
6
7 #include "base/callback.h"
8 #include "base/location.h"
9 #include "base/message_loop/message_loop_proxy.h"
10 #include "base/task_runner.h"
11
12 using base::TaskRunner;
13
14 namespace extensions {
15
16 struct OneShotEvent::TaskInfo {
TaskInfoextensions::OneShotEvent::TaskInfo17 TaskInfo() {}
TaskInfoextensions::OneShotEvent::TaskInfo18 TaskInfo(const tracked_objects::Location& from_here,
19 const scoped_refptr<TaskRunner>& runner,
20 const base::Closure& task)
21 : from_here(from_here), runner(runner), task(task) {
22 CHECK(runner.get()); // Detect mistakes with a decent stack frame.
23 }
24 tracked_objects::Location from_here;
25 scoped_refptr<TaskRunner> runner;
26 base::Closure task;
27 };
28
OneShotEvent()29 OneShotEvent::OneShotEvent() : signaled_(false) {
30 // It's acceptable to construct the OneShotEvent on one thread, but
31 // immediately move it to another thread.
32 thread_checker_.DetachFromThread();
33 }
~OneShotEvent()34 OneShotEvent::~OneShotEvent() {}
35
Post(const tracked_objects::Location & from_here,const base::Closure & task) const36 void OneShotEvent::Post(const tracked_objects::Location& from_here,
37 const base::Closure& task) const {
38 Post(from_here, task, base::MessageLoopProxy::current());
39 }
40
Post(const tracked_objects::Location & from_here,const base::Closure & task,const scoped_refptr<TaskRunner> & runner) const41 void OneShotEvent::Post(const tracked_objects::Location& from_here,
42 const base::Closure& task,
43 const scoped_refptr<TaskRunner>& runner) const {
44 DCHECK(thread_checker_.CalledOnValidThread());
45
46 if (is_signaled()) {
47 runner->PostTask(from_here, task);
48 } else {
49 tasks_.push_back(TaskInfo(from_here, runner, task));
50 }
51 }
52
Signal()53 void OneShotEvent::Signal() {
54 DCHECK(thread_checker_.CalledOnValidThread());
55
56 CHECK(!signaled_) << "Only call Signal once.";
57
58 signaled_ = true;
59 // After this point, a call to Post() from one of the queued tasks
60 // could proceed immediately, but the fact that this object is
61 // single-threaded prevents that from being relevant.
62
63 // We could randomize tasks_ in debug mode in order to check that
64 // the order doesn't matter...
65 for (size_t i = 0; i < tasks_.size(); ++i) {
66 tasks_[i].runner->PostTask(tasks_[i].from_here, tasks_[i].task);
67 }
68 }
69
70 } // namespace extensions
71