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| 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 #include "base/threading/post_task_and_reply_impl.h" | 5 #include "base/threading/post_task_and_reply_impl.h" |
| 6 | 6 |
| 7 #include "base/bind.h" | 7 #include "base/bind.h" |
| 8 #include "base/location.h" | 8 #include "base/location.h" |
| 9 #include "base/single_thread_task_runner.h" | 9 #include "base/single_thread_task_runner.h" |
| 10 #include "base/thread_task_runner_handle.h" | 10 #include "base/thread_task_runner_handle.h" |
| 11 | 11 |
| 12 namespace base { | 12 namespace base { |
| 13 | 13 |
| 14 namespace { | 14 namespace { |
| 15 | 15 |
| 16 // This relay class remembers the MessageLoop that it was created on, and | 16 // This relay class remembers the MessageLoop that it was created on, and |
| 17 // ensures that both the |task| and |reply| Closures are deleted on this same | 17 // ensures that both the |task| and |reply| Closures are deleted on this same |
| 18 // thread. Also, |task| is guaranteed to be deleted before |reply| is run or | 18 // thread. Also, |task| is guaranteed to be deleted before |reply| is run or |
| 19 // deleted. | 19 // deleted. |
| 20 // | 20 // |
| 21 // If this is not possible because the originating MessageLoop is no longer | 21 // If this is not possible because the originating MessageLoop is no longer |
| 22 // available, the the |task| and |reply| Closures are leaked. Leaking is | 22 // available, the the |task| and |reply| Closures are leaked. Leaking is |
| 23 // considered preferable to having a thread-safetey violations caused by | 23 // considered preferable to having a thread-safetey violations caused by |
| 24 // invoking the Closure destructor on the wrong thread. | 24 // invoking the Closure destructor on the wrong thread. |
| 25 class PostTaskAndReplyRelay { | 25 class PostTaskAndReplyRelay { |
| 26 public: | 26 public: |
| 27 PostTaskAndReplyRelay(const tracked_objects::Location& from_here, | 27 PostTaskAndReplyRelay(const tracked_objects::Location& from_here, |
| 28 const Closure& task, const Closure& reply) | 28 const Closure& task, |
| 29 const Closure& reply) |
| 29 : from_here_(from_here), | 30 : from_here_(from_here), |
| 30 origin_loop_(ThreadTaskRunnerHandle::Get()) { | 31 origin_task_runner_(ThreadTaskRunnerHandle::Get()) { |
| 31 task_ = task; | 32 task_ = task; |
| 32 reply_ = reply; | 33 reply_ = reply; |
| 33 } | 34 } |
| 34 | 35 |
| 35 ~PostTaskAndReplyRelay() { | 36 ~PostTaskAndReplyRelay() { |
| 36 DCHECK(origin_loop_->BelongsToCurrentThread()); | 37 DCHECK(origin_task_runner_->BelongsToCurrentThread()); |
| 37 task_.Reset(); | 38 task_.Reset(); |
| 38 reply_.Reset(); | 39 reply_.Reset(); |
| 39 } | 40 } |
| 40 | 41 |
| 41 void Run() { | 42 void Run() { |
| 42 task_.Run(); | 43 task_.Run(); |
| 43 origin_loop_->PostTask( | 44 origin_task_runner_->PostTask( |
| 44 from_here_, | 45 from_here_, Bind(&PostTaskAndReplyRelay::RunReplyAndSelfDestruct, |
| 45 Bind(&PostTaskAndReplyRelay::RunReplyAndSelfDestruct, | 46 base::Unretained(this))); |
| 46 base::Unretained(this))); | |
| 47 } | 47 } |
| 48 | 48 |
| 49 private: | 49 private: |
| 50 void RunReplyAndSelfDestruct() { | 50 void RunReplyAndSelfDestruct() { |
| 51 DCHECK(origin_loop_->BelongsToCurrentThread()); | 51 DCHECK(origin_task_runner_->BelongsToCurrentThread()); |
| 52 | 52 |
| 53 // Force |task_| to be released before |reply_| is to ensure that no one | 53 // Force |task_| to be released before |reply_| is to ensure that no one |
| 54 // accidentally depends on |task_| keeping one of its arguments alive while | 54 // accidentally depends on |task_| keeping one of its arguments alive while |
| 55 // |reply_| is executing. | 55 // |reply_| is executing. |
| 56 task_.Reset(); | 56 task_.Reset(); |
| 57 | 57 |
| 58 reply_.Run(); | 58 reply_.Run(); |
| 59 | 59 |
| 60 // Cue mission impossible theme. | 60 // Cue mission impossible theme. |
| 61 delete this; | 61 delete this; |
| 62 } | 62 } |
| 63 | 63 |
| 64 tracked_objects::Location from_here_; | 64 tracked_objects::Location from_here_; |
| 65 scoped_refptr<SingleThreadTaskRunner> origin_loop_; | 65 scoped_refptr<SingleThreadTaskRunner> origin_task_runner_; |
| 66 Closure reply_; | 66 Closure reply_; |
| 67 Closure task_; | 67 Closure task_; |
| 68 }; | 68 }; |
| 69 | 69 |
| 70 } // namespace | 70 } // namespace |
| 71 | 71 |
| 72 namespace internal { | 72 namespace internal { |
| 73 | 73 |
| 74 bool PostTaskAndReplyImpl::PostTaskAndReply( | 74 bool PostTaskAndReplyImpl::PostTaskAndReply( |
| 75 const tracked_objects::Location& from_here, | 75 const tracked_objects::Location& from_here, |
| 76 const Closure& task, | 76 const Closure& task, |
| 77 const Closure& reply) { | 77 const Closure& reply) { |
| 78 PostTaskAndReplyRelay* relay = | 78 PostTaskAndReplyRelay* relay = |
| 79 new PostTaskAndReplyRelay(from_here, task, reply); | 79 new PostTaskAndReplyRelay(from_here, task, reply); |
| 80 if (!PostTask(from_here, Bind(&PostTaskAndReplyRelay::Run, | 80 if (!PostTask(from_here, Bind(&PostTaskAndReplyRelay::Run, |
| 81 Unretained(relay)))) { | 81 Unretained(relay)))) { |
| 82 delete relay; | 82 delete relay; |
| 83 return false; | 83 return false; |
| 84 } | 84 } |
| 85 | 85 |
| 86 return true; | 86 return true; |
| 87 } | 87 } |
| 88 | 88 |
| 89 } // namespace internal | 89 } // namespace internal |
| 90 | 90 |
| 91 } // namespace base | 91 } // namespace base |
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