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/lazy_instance.h"
9 #include "base/location.h"
10 #include "base/message_loop/message_loop_proxy.h"
11 #include "base/task_runner.h"
12 #include "base/time/time.h"
13
14 using base::TaskRunner;
15
16 namespace extensions {
17
18 struct OneShotEvent::TaskInfo {
TaskInfoextensions::OneShotEvent::TaskInfo19 TaskInfo() {}
TaskInfoextensions::OneShotEvent::TaskInfo20 TaskInfo(const tracked_objects::Location& from_here,
21 const scoped_refptr<TaskRunner>& runner,
22 const base::Closure& task,
23 const base::TimeDelta& delay)
24 : from_here(from_here), runner(runner), task(task), delay(delay) {
25 CHECK(runner.get()); // Detect mistakes with a decent stack frame.
26 }
27 tracked_objects::Location from_here;
28 scoped_refptr<TaskRunner> runner;
29 base::Closure task;
30 base::TimeDelta delay;
31 };
32
OneShotEvent()33 OneShotEvent::OneShotEvent() : signaled_(false) {
34 // It's acceptable to construct the OneShotEvent on one thread, but
35 // immediately move it to another thread.
36 thread_checker_.DetachFromThread();
37 }
OneShotEvent(bool signaled)38 OneShotEvent::OneShotEvent(bool signaled) : signaled_(signaled) {
39 thread_checker_.DetachFromThread();
40 }
~OneShotEvent()41 OneShotEvent::~OneShotEvent() {}
42
Post(const tracked_objects::Location & from_here,const base::Closure & task) const43 void OneShotEvent::Post(const tracked_objects::Location& from_here,
44 const base::Closure& task) const {
45 PostImpl(
46 from_here, task, base::MessageLoopProxy::current(), base::TimeDelta());
47 }
48
Post(const tracked_objects::Location & from_here,const base::Closure & task,const scoped_refptr<TaskRunner> & runner) const49 void OneShotEvent::Post(const tracked_objects::Location& from_here,
50 const base::Closure& task,
51 const scoped_refptr<TaskRunner>& runner) const {
52 PostImpl(from_here, task, runner, base::TimeDelta());
53 }
54
PostDelayed(const tracked_objects::Location & from_here,const base::Closure & task,const base::TimeDelta & delay) const55 void OneShotEvent::PostDelayed(const tracked_objects::Location& from_here,
56 const base::Closure& task,
57 const base::TimeDelta& delay) const {
58 PostImpl(from_here, task, base::MessageLoopProxy::current(), delay);
59 }
60
Signal()61 void OneShotEvent::Signal() {
62 DCHECK(thread_checker_.CalledOnValidThread());
63
64 CHECK(!signaled_) << "Only call Signal once.";
65
66 signaled_ = true;
67 // After this point, a call to Post() from one of the queued tasks
68 // could proceed immediately, but the fact that this object is
69 // single-threaded prevents that from being relevant.
70
71 // We could randomize tasks_ in debug mode in order to check that
72 // the order doesn't matter...
73 for (size_t i = 0; i < tasks_.size(); ++i) {
74 const TaskInfo& task = tasks_[i];
75 if (task.delay != base::TimeDelta())
76 task.runner->PostDelayedTask(task.from_here, task.task, task.delay);
77 else
78 task.runner->PostTask(task.from_here, task.task);
79 }
80 }
81
PostImpl(const tracked_objects::Location & from_here,const base::Closure & task,const scoped_refptr<TaskRunner> & runner,const base::TimeDelta & delay) const82 void OneShotEvent::PostImpl(const tracked_objects::Location& from_here,
83 const base::Closure& task,
84 const scoped_refptr<TaskRunner>& runner,
85 const base::TimeDelta& delay) const {
86 DCHECK(thread_checker_.CalledOnValidThread());
87
88 if (is_signaled()) {
89 if (delay != base::TimeDelta())
90 runner->PostDelayedTask(from_here, task, delay);
91 else
92 runner->PostTask(from_here, task);
93 } else {
94 tasks_.push_back(TaskInfo(from_here, runner, task, delay));
95 }
96 }
97
98 } // namespace extensions
99