OLD | NEW |
| (Empty) |
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 "chrome/common/cancelable_task_tracker.h" | |
6 | |
7 #include <utility> | |
8 | |
9 #include "base/bind.h" | |
10 #include "base/callback_helpers.h" | |
11 #include "base/compiler_specific.h" | |
12 #include "base/location.h" | |
13 #include "base/memory/ref_counted.h" | |
14 #include "base/message_loop/message_loop_proxy.h" | |
15 #include "base/synchronization/cancellation_flag.h" | |
16 #include "base/task_runner.h" | |
17 | |
18 using base::Bind; | |
19 using base::CancellationFlag; | |
20 using base::Closure; | |
21 using base::hash_map; | |
22 using base::TaskRunner; | |
23 | |
24 namespace { | |
25 | |
26 void RunIfNotCanceled(const CancellationFlag* flag, const Closure& task) { | |
27 if (!flag->IsSet()) | |
28 task.Run(); | |
29 } | |
30 | |
31 void RunIfNotCanceledThenUntrack(const CancellationFlag* flag, | |
32 const Closure& task, | |
33 const Closure& untrack) { | |
34 RunIfNotCanceled(flag, task); | |
35 untrack.Run(); | |
36 } | |
37 | |
38 bool IsCanceled(const CancellationFlag* flag, | |
39 base::ScopedClosureRunner* cleanup_runner) { | |
40 return flag->IsSet(); | |
41 } | |
42 | |
43 void RunAndDeleteFlag(const Closure& closure, const CancellationFlag* flag) { | |
44 closure.Run(); | |
45 delete flag; | |
46 } | |
47 | |
48 void RunOrPostToTaskRunner(TaskRunner* task_runner, const Closure& closure) { | |
49 if (task_runner->RunsTasksOnCurrentThread()) | |
50 closure.Run(); | |
51 else | |
52 task_runner->PostTask(FROM_HERE, closure); | |
53 } | |
54 | |
55 } // namespace | |
56 | |
57 // static | |
58 const CancelableTaskTracker::TaskId CancelableTaskTracker::kBadTaskId = 0; | |
59 | |
60 CancelableTaskTracker::CancelableTaskTracker() | |
61 : weak_factory_(this), | |
62 next_id_(1) {} | |
63 | |
64 CancelableTaskTracker::~CancelableTaskTracker() { | |
65 DCHECK(thread_checker_.CalledOnValidThread()); | |
66 | |
67 TryCancelAll(); | |
68 } | |
69 | |
70 CancelableTaskTracker::TaskId CancelableTaskTracker::PostTask( | |
71 TaskRunner* task_runner, | |
72 const tracked_objects::Location& from_here, | |
73 const Closure& task) { | |
74 DCHECK(thread_checker_.CalledOnValidThread()); | |
75 | |
76 return PostTaskAndReply(task_runner, from_here, task, Bind(&base::DoNothing)); | |
77 } | |
78 | |
79 CancelableTaskTracker::TaskId CancelableTaskTracker::PostTaskAndReply( | |
80 TaskRunner* task_runner, | |
81 const tracked_objects::Location& from_here, | |
82 const Closure& task, | |
83 const Closure& reply) { | |
84 DCHECK(thread_checker_.CalledOnValidThread()); | |
85 | |
86 // We need a MessageLoop to run reply. | |
87 DCHECK(base::MessageLoopProxy::current().get()); | |
88 | |
89 // Owned by reply callback below. | |
90 CancellationFlag* flag = new CancellationFlag(); | |
91 | |
92 TaskId id = next_id_; | |
93 next_id_++; // int64 is big enough that we ignore the potential overflow. | |
94 | |
95 const Closure& untrack_closure = Bind( | |
96 &CancelableTaskTracker::Untrack, weak_factory_.GetWeakPtr(), id); | |
97 bool success = task_runner->PostTaskAndReply( | |
98 from_here, | |
99 Bind(&RunIfNotCanceled, flag, task), | |
100 Bind(&RunIfNotCanceledThenUntrack, | |
101 base::Owned(flag), reply, untrack_closure)); | |
102 | |
103 if (!success) | |
104 return kBadTaskId; | |
105 | |
106 Track(id, flag); | |
107 return id; | |
108 } | |
109 | |
110 CancelableTaskTracker::TaskId CancelableTaskTracker::NewTrackedTaskId( | |
111 IsCanceledCallback* is_canceled_cb) { | |
112 DCHECK(thread_checker_.CalledOnValidThread()); | |
113 DCHECK(base::MessageLoopProxy::current().get()); | |
114 | |
115 TaskId id = next_id_; | |
116 next_id_++; // int64 is big enough that we ignore the potential overflow. | |
117 | |
118 // Will be deleted by |untrack_and_delete_flag| after Untrack(). | |
119 CancellationFlag* flag = new CancellationFlag(); | |
120 | |
121 Closure untrack_and_delete_flag = Bind( | |
122 &RunAndDeleteFlag, | |
123 Bind(&CancelableTaskTracker::Untrack, weak_factory_.GetWeakPtr(), id), | |
124 flag); | |
125 | |
126 // Will always run |untrack_and_delete_flag| on current MessageLoop. | |
127 base::ScopedClosureRunner* untrack_and_delete_flag_runner = | |
128 new base::ScopedClosureRunner( | |
129 Bind(&RunOrPostToTaskRunner, | |
130 base::MessageLoopProxy::current(), | |
131 untrack_and_delete_flag)); | |
132 | |
133 *is_canceled_cb = Bind( | |
134 &IsCanceled, flag, base::Owned(untrack_and_delete_flag_runner)); | |
135 | |
136 Track(id, flag); | |
137 return id; | |
138 } | |
139 | |
140 void CancelableTaskTracker::TryCancel(TaskId id) { | |
141 DCHECK(thread_checker_.CalledOnValidThread()); | |
142 | |
143 hash_map<TaskId, CancellationFlag*>::const_iterator it = task_flags_.find(id); | |
144 if (it == task_flags_.end()) { | |
145 // Two possibilities: | |
146 // | |
147 // 1. The task has already been untracked. | |
148 // 2. The TaskId is bad or unknown. | |
149 // | |
150 // Since this function is best-effort, it's OK to ignore these. | |
151 return; | |
152 } | |
153 it->second->Set(); | |
154 } | |
155 | |
156 void CancelableTaskTracker::TryCancelAll() { | |
157 DCHECK(thread_checker_.CalledOnValidThread()); | |
158 | |
159 for (hash_map<TaskId, CancellationFlag*>::const_iterator it = | |
160 task_flags_.begin(); | |
161 it != task_flags_.end(); | |
162 ++it) { | |
163 it->second->Set(); | |
164 } | |
165 } | |
166 | |
167 bool CancelableTaskTracker::HasTrackedTasks() const { | |
168 DCHECK(thread_checker_.CalledOnValidThread()); | |
169 return !task_flags_.empty(); | |
170 } | |
171 | |
172 void CancelableTaskTracker::Track(TaskId id, CancellationFlag* flag) { | |
173 DCHECK(thread_checker_.CalledOnValidThread()); | |
174 | |
175 bool success = task_flags_.insert(std::make_pair(id, flag)).second; | |
176 DCHECK(success); | |
177 } | |
178 | |
179 void CancelableTaskTracker::Untrack(TaskId id) { | |
180 DCHECK(thread_checker_.CalledOnValidThread()); | |
181 size_t num = task_flags_.erase(id); | |
182 DCHECK_EQ(1u, num); | |
183 } | |
OLD | NEW |