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| 1 // Copyright 2014 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 "base/task/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/single_thread_task_runner.h" | |
| 15 #include "base/synchronization/cancellation_flag.h" | |
| 16 #include "base/task_runner.h" | |
| 17 #include "base/thread_task_runner_handle.h" | |
| 18 | |
| 19 using base::Bind; | |
| 20 using base::CancellationFlag; | |
| 21 using base::Closure; | |
| 22 using base::hash_map; | |
| 23 using base::TaskRunner; | |
| 24 | |
| 25 namespace { | |
| 26 | |
| 27 void RunIfNotCanceled(const CancellationFlag* flag, const Closure& task) { | |
| 28 if (!flag->IsSet()) | |
| 29 task.Run(); | |
| 30 } | |
| 31 | |
| 32 void RunIfNotCanceledThenUntrack(const CancellationFlag* flag, | |
| 33 const Closure& task, | |
| 34 const Closure& untrack) { | |
| 35 RunIfNotCanceled(flag, task); | |
| 36 untrack.Run(); | |
| 37 } | |
| 38 | |
| 39 bool IsCanceled(const CancellationFlag* flag, | |
| 40 base::ScopedClosureRunner* cleanup_runner) { | |
| 41 return flag->IsSet(); | |
| 42 } | |
| 43 | |
| 44 void RunAndDeleteFlag(const Closure& closure, const CancellationFlag* flag) { | |
| 45 closure.Run(); | |
| 46 delete flag; | |
| 47 } | |
| 48 | |
| 49 void RunOrPostToTaskRunner(TaskRunner* task_runner, const Closure& closure) { | |
| 50 if (task_runner->RunsTasksOnCurrentThread()) | |
| 51 closure.Run(); | |
| 52 else | |
| 53 task_runner->PostTask(FROM_HERE, closure); | |
| 54 } | |
| 55 | |
| 56 } // namespace | |
| 57 | |
| 58 namespace base { | |
| 59 | |
| 60 // static | |
| 61 const CancelableTaskTracker::TaskId CancelableTaskTracker::kBadTaskId = 0; | |
| 62 | |
| 63 CancelableTaskTracker::CancelableTaskTracker() | |
| 64 : next_id_(1),weak_factory_(this) {} | |
| 65 | |
| 66 CancelableTaskTracker::~CancelableTaskTracker() { | |
| 67 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 68 | |
| 69 TryCancelAll(); | |
| 70 } | |
| 71 | |
| 72 CancelableTaskTracker::TaskId CancelableTaskTracker::PostTask( | |
| 73 TaskRunner* task_runner, | |
| 74 const tracked_objects::Location& from_here, | |
| 75 const Closure& task) { | |
| 76 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 77 | |
| 78 return PostTaskAndReply(task_runner, from_here, task, Bind(&base::DoNothing)); | |
| 79 } | |
| 80 | |
| 81 CancelableTaskTracker::TaskId CancelableTaskTracker::PostTaskAndReply( | |
| 82 TaskRunner* task_runner, | |
| 83 const tracked_objects::Location& from_here, | |
| 84 const Closure& task, | |
| 85 const Closure& reply) { | |
| 86 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 87 | |
| 88 // We need a MessageLoop to run reply. | |
| 89 DCHECK(base::ThreadTaskRunnerHandle::IsSet()); | |
| 90 | |
| 91 // Owned by reply callback below. | |
| 92 CancellationFlag* flag = new CancellationFlag(); | |
| 93 | |
| 94 TaskId id = next_id_; | |
| 95 next_id_++; // int64 is big enough that we ignore the potential overflow. | |
| 96 | |
| 97 const Closure& untrack_closure = | |
| 98 Bind(&CancelableTaskTracker::Untrack, weak_factory_.GetWeakPtr(), id); | |
| 99 bool success = | |
| 100 task_runner->PostTaskAndReply(from_here, | |
| 101 Bind(&RunIfNotCanceled, flag, task), | |
| 102 Bind(&RunIfNotCanceledThenUntrack, | |
| 103 base::Owned(flag), | |
| 104 reply, | |
| 105 untrack_closure)); | |
| 106 | |
| 107 if (!success) | |
| 108 return kBadTaskId; | |
| 109 | |
| 110 Track(id, flag); | |
| 111 return id; | |
| 112 } | |
| 113 | |
| 114 CancelableTaskTracker::TaskId CancelableTaskTracker::NewTrackedTaskId( | |
| 115 IsCanceledCallback* is_canceled_cb) { | |
| 116 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 117 DCHECK(base::ThreadTaskRunnerHandle::IsSet()); | |
| 118 | |
| 119 TaskId id = next_id_; | |
| 120 next_id_++; // int64 is big enough that we ignore the potential overflow. | |
| 121 | |
| 122 // Will be deleted by |untrack_and_delete_flag| after Untrack(). | |
| 123 CancellationFlag* flag = new CancellationFlag(); | |
| 124 | |
| 125 Closure untrack_and_delete_flag = Bind( | |
| 126 &RunAndDeleteFlag, | |
| 127 Bind(&CancelableTaskTracker::Untrack, weak_factory_.GetWeakPtr(), id), | |
| 128 flag); | |
| 129 | |
| 130 // Will always run |untrack_and_delete_flag| on current MessageLoop. | |
| 131 base::ScopedClosureRunner* untrack_and_delete_flag_runner = | |
| 132 new base::ScopedClosureRunner(Bind(&RunOrPostToTaskRunner, | |
| 133 base::ThreadTaskRunnerHandle::Get(), | |
| 134 untrack_and_delete_flag)); | |
| 135 | |
| 136 *is_canceled_cb = | |
| 137 Bind(&IsCanceled, flag, base::Owned(untrack_and_delete_flag_runner)); | |
| 138 | |
| 139 Track(id, flag); | |
| 140 return id; | |
| 141 } | |
| 142 | |
| 143 void CancelableTaskTracker::TryCancel(TaskId id) { | |
| 144 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 145 | |
| 146 hash_map<TaskId, CancellationFlag*>::const_iterator it = task_flags_.find(id); | |
| 147 if (it == task_flags_.end()) { | |
| 148 // Two possibilities: | |
| 149 // | |
| 150 // 1. The task has already been untracked. | |
| 151 // 2. The TaskId is bad or unknown. | |
| 152 // | |
| 153 // Since this function is best-effort, it's OK to ignore these. | |
| 154 return; | |
| 155 } | |
| 156 it->second->Set(); | |
| 157 } | |
| 158 | |
| 159 void CancelableTaskTracker::TryCancelAll() { | |
| 160 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 161 | |
| 162 for (hash_map<TaskId, CancellationFlag*>::const_iterator it = | |
| 163 task_flags_.begin(); | |
| 164 it != task_flags_.end(); | |
| 165 ++it) { | |
| 166 it->second->Set(); | |
| 167 } | |
| 168 } | |
| 169 | |
| 170 bool CancelableTaskTracker::HasTrackedTasks() const { | |
| 171 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 172 return !task_flags_.empty(); | |
| 173 } | |
| 174 | |
| 175 void CancelableTaskTracker::Track(TaskId id, CancellationFlag* flag) { | |
| 176 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 177 | |
| 178 bool success = task_flags_.insert(std::make_pair(id, flag)).second; | |
| 179 DCHECK(success); | |
| 180 } | |
| 181 | |
| 182 void CancelableTaskTracker::Untrack(TaskId id) { | |
| 183 DCHECK(thread_checker_.CalledOnValidThread()); | |
| 184 size_t num = task_flags_.erase(id); | |
| 185 DCHECK_EQ(1u, num); | |
| 186 } | |
| 187 | |
| 188 } // namespace base | |
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