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1 // Copyright 2016 The Chromium Authors. All rights reserved. | 1 // Copyright 2016 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/task_scheduler/scheduler_worker_thread.h" | 5 #include "base/task_scheduler/scheduler_worker_thread.h" |
6 | 6 |
7 #include <stddef.h> | 7 #include <stddef.h> |
8 | 8 |
9 #include <utility> | 9 #include <utility> |
10 | 10 |
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67 while (!task_tracker_->shutdown_completed() && !ShouldExitForTesting()) { | 67 while (!task_tracker_->shutdown_completed() && !ShouldExitForTesting()) { |
68 // Get the sequence containing the next task to execute. | 68 // Get the sequence containing the next task to execute. |
69 scoped_refptr<Sequence> sequence = delegate_->GetWork(this); | 69 scoped_refptr<Sequence> sequence = delegate_->GetWork(this); |
70 | 70 |
71 if (!sequence) { | 71 if (!sequence) { |
72 wake_up_event_.Wait(); | 72 wake_up_event_.Wait(); |
73 continue; | 73 continue; |
74 } | 74 } |
75 | 75 |
76 task_tracker_->RunTask(sequence->PeekTask()); | 76 task_tracker_->RunTask(sequence->PeekTask()); |
77 delegate_->RanTaskFromSequence(std::move(sequence)); | 77 |
| 78 const bool sequence_became_empty = sequence->PopTask(); |
| 79 |
| 80 // If |sequence| isn't empty immediately after the pop, enqueue it to |
| 81 // maintain the invariant that a non-empty Sequence is always referenced by |
| 82 // either a PriorityQueue or a SchedulerWorkerThread. If it is empty and |
| 83 // there are live references to it, it will be enqueued when a Task is added |
| 84 // to it. Otherwise, it will be destroyed at the end of this scope. |
| 85 if (!sequence_became_empty) |
| 86 delegate_->EnqueueSequence(std::move(sequence)); |
78 | 87 |
79 // Calling WakeUp() guarantees that this SchedulerWorkerThread will run | 88 // Calling WakeUp() guarantees that this SchedulerWorkerThread will run |
80 // Tasks from Sequences returned by the GetWork() method of |delegate_| | 89 // Tasks from Sequences returned by the GetWork() method of |delegate_| |
81 // until it returns nullptr. Resetting |wake_up_event_| here doesn't break | 90 // until it returns nullptr. Resetting |wake_up_event_| here doesn't break |
82 // this invariant and avoids a useless loop iteration before going to sleep | 91 // this invariant and avoids a useless loop iteration before going to sleep |
83 // if WakeUp() is called while this SchedulerWorkerThread is awake. | 92 // if WakeUp() is called while this SchedulerWorkerThread is awake. |
84 wake_up_event_.Reset(); | 93 wake_up_event_.Reset(); |
85 } | 94 } |
86 | 95 |
87 delegate_->OnMainExit(); | 96 delegate_->OnMainExit(); |
88 } | 97 } |
89 | 98 |
90 bool SchedulerWorkerThread::ShouldExitForTesting() const { | 99 bool SchedulerWorkerThread::ShouldExitForTesting() const { |
91 AutoSchedulerLock auto_lock(should_exit_for_testing_lock_); | 100 AutoSchedulerLock auto_lock(should_exit_for_testing_lock_); |
92 return should_exit_for_testing_; | 101 return should_exit_for_testing_; |
93 } | 102 } |
94 | 103 |
95 } // namespace internal | 104 } // namespace internal |
96 } // namespace base | 105 } // namespace base |
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