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| 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 |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef BASE_TASK_SCHEDULER_WORKER_THREAD_H_ |
| 6 #define BASE_TASK_SCHEDULER_WORKER_THREAD_H_ |
| 7 |
| 8 #include "base/base_export.h" |
| 9 #include "base/callback.h" |
| 10 #include "base/macros.h" |
| 11 #include "base/memory/ref_counted.h" |
| 12 #include "base/single_thread_task_runner.h" |
| 13 #include "base/synchronization/condition_variable.h" |
| 14 #include "base/task_scheduler/priority_queue.h" |
| 15 #include "base/task_scheduler/scheduler_lock.h" |
| 16 #include "base/task_scheduler/sequence.h" |
| 17 #include "base/task_scheduler/task_traits.h" |
| 18 #include "base/threading/platform_thread.h" |
| 19 |
| 20 namespace base { |
| 21 namespace internal { |
| 22 |
| 23 class TaskTracker; |
| 24 |
| 25 // A thread that runs tasks from a shared and a single-threaded priority queue. |
| 26 // This class is thread-safe. |
| 27 class BASE_EXPORT WorkerThread : public PlatformThread::Delegate { |
| 28 public: |
| 29 // Callback invoked by |worker_thread| to reinsert |sequence| in the |
| 30 // appropriate priority queue it has executed one of its tasks. |
| 31 using ReinsertSequenceCallback = |
| 32 Callback<void(scoped_refptr<Sequence> sequence, |
| 33 const WorkerThread* worker_thread)>; |
| 34 |
| 35 // Callback invoked when |worker_thread| becomes idle. |
| 36 using BecomesIdleCallback = Callback<void(WorkerThread* worker_thread)>; |
| 37 |
| 38 // Creates a WorkerThread with priority |thread_priority| that runs tasks from |
| 39 // a single-thread priority queue and from |shared_priority_queue|. |
| 40 // |reinsert_sequence_callback| is invoked to reinsert a sequence in the |
| 41 // appropriate priority queue after one of its tasks has been executed. |
| 42 // |task_tracker| is used to handle shutdown behavior of tasks. |
| 43 static scoped_ptr<WorkerThread> CreateWorkerThread( |
| 44 ThreadPriority thread_priority, |
| 45 PriorityQueue* shared_priority_queue, |
| 46 const ReinsertSequenceCallback& reinsert_sequence_callback, |
| 47 const BecomesIdleCallback& becomes_idle_callback, |
| 48 TaskTracker* task_tracker); |
| 49 |
| 50 // A WorkerThread must only be destroyed after JoinForTesting() has returned. |
| 51 ~WorkerThread() override; |
| 52 |
| 53 // Wakes up the WorkerThread. Returns false if it was already awake. |
| 54 bool WakeUp(); |
| 55 |
| 56 // Returns a SingleThreadTaskRunner whose PostTask invocations will result in |
| 57 // scheduling tasks on this WorkerThread with |traits|. |
| 58 scoped_refptr<SingleThreadTaskRunner> CreateTaskRunnerWithTraits( |
| 59 const TaskTraits& traits); |
| 60 |
| 61 // Joins the WorkerThread. If a task is already running, it will be allowed |
| 62 // to complete its execution. This can only be called once. |
| 63 void JoinForTesting(); |
| 64 |
| 65 private: |
| 66 WorkerThread(ThreadPriority thread_priority, |
| 67 PriorityQueue* shared_priority_queue, |
| 68 const ReinsertSequenceCallback& reinsert_sequence_callback, |
| 69 const BecomesIdleCallback& becomes_idle_callback, |
| 70 TaskTracker* task_tracker); |
| 71 |
| 72 // Extracts the sequence with the highest priority from |
| 73 // |shared_priority_queue_| or |single_thread_priority_queue_|. |
| 74 // |single_thread| is set to true if the returned task comes from |
| 75 // |single_thread_priority_queue_|. |
| 76 scoped_refptr<Sequence> GetWork(bool* single_thread); |
| 77 |
| 78 // Waits until |is_awake_| becomes true. |
| 79 void WaitUntilWakeUp(); |
| 80 |
| 81 // PlatformThread::Delegate: |
| 82 void ThreadMain() override; |
| 83 |
| 84 // Platform thread managed by this WorkerThread. |
| 85 PlatformThreadHandle thread_handle_; |
| 86 |
| 87 // Synchronizes access to |wake_up_cv_|, |is_awake_| and |
| 88 // |should_exit_for_testing_|. |
| 89 SchedulerLock lock_; |
| 90 |
| 91 // Condition variable signaled when |is_awake_| becomes true. |
| 92 mutable scoped_ptr<ConditionVariable> wake_up_cv_; |
| 93 |
| 94 // True from the time WakeUp() is called to the time the WorkerThread doesn't |
| 95 // have any remaining work to do. |
| 96 bool is_awake_; |
| 97 |
| 98 // True once JoinForTesting() has been called. |
| 99 bool should_exit_for_testing_; |
| 100 |
| 101 // The single-threaded priority queue from which the WorkerThread gets work. |
| 102 PriorityQueue single_thread_priority_queue_; |
| 103 |
| 104 // The shared priority queue from which the WorkerThread gets work. |
| 105 PriorityQueue* const shared_priority_queue_; |
| 106 |
| 107 const ReinsertSequenceCallback reinsert_sequence_callback_; |
| 108 const BecomesIdleCallback becomes_idle_callback_; |
| 109 TaskTracker* const task_tracker_; |
| 110 |
| 111 DISALLOW_COPY_AND_ASSIGN(WorkerThread); |
| 112 }; |
| 113 |
| 114 } // namespace internal |
| 115 } // namespace base |
| 116 |
| 117 #endif // BASE_TASK_SCHEDULER_WORKER_THREAD_H_ |
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