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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_forward.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/waitable_event.h" | |
14 #include "base/task_scheduler/priority_queue.h" | |
15 #include "base/task_scheduler/sequence.h" | |
16 #include "base/task_scheduler/task_traits.h" | |
17 #include "base/threading/platform_thread.h" | |
18 | |
19 namespace base { | |
20 namespace task_scheduler { | |
21 | |
22 class DelayedTaskManager; | |
23 class ShutdownManager; | |
24 | |
25 // A thread that runs tasks from a shared and a single-threaded priority queue. | |
26 // Unless otherwise noted, all public methods of this class are thread-safe. | |
27 class BASE_EXPORT WorkerThread : public PlatformThread::Delegate { | |
28 public: | |
29 // Callback to reinsert |sequence| in the appropriate priority queue after one | |
30 // of its tasks has been executed. |worker_thread| is the worker thread that | |
31 // invokes the callback. | |
32 using ReinsertSequenceCallback = | |
33 Callback<void(scoped_refptr<Sequence> sequence, | |
34 const WorkerThread* worker_thread)>; | |
35 | |
36 // Callback invoked when the worker thread becomes idle. |worker_thread| is | |
37 // the worker thread that invokes the callback. | |
38 using BecomesIdleCallback = Callback<void(WorkerThread* worker_thread)>; | |
39 | |
40 // Creates a worker thread that runs tasks from a single-thread priority queue | |
41 // and from |shared_priority_queue| with |thread_priority|. | |
42 // |reinsert_sequence_callback| is invoked to reinsert a sequence in the | |
43 // appropriate priority queue after one of its tasks has been executed. | |
44 // |delayed_task_manager| is used to handle delayed tasks. |shutdown_manager| | |
45 // is used to handle shutdown behavior of tasks. | |
46 static scoped_ptr<WorkerThread> CreateWorkerThread( | |
47 ThreadPriority thread_priority, | |
48 PriorityQueue* shared_priority_queue, | |
49 const ReinsertSequenceCallback& reinsert_sequence_callback, | |
50 const BecomesIdleCallback& becomes_idle_callback, | |
51 DelayedTaskManager* delayed_task_manager, | |
52 ShutdownManager* shutdown_manager); | |
53 | |
54 ~WorkerThread() override; | |
55 | |
56 // Wakes up the worker thread. Soon after this is called, the thread starts | |
57 // running tasks from its priority queue. It continues to run tasks until its | |
58 // priority queue is empty. Has no effect if the worker thread is already | |
59 // running tasks. | |
60 void WakeUp(); | |
61 | |
62 // Returns a SingleThreadTaskRunner whose PostTask invocations will result in | |
63 // scheduling tasks on this worker thread with traits |traits|. | |
64 scoped_refptr<SingleThreadTaskRunner> CreateTaskRunnerWithTraits( | |
65 const TaskTraits& traits, | |
66 ExecutionMode execution_mode); | |
67 | |
68 // Returns true if the worker thread has single-threaded tasks (running or | |
69 // pending). Use a memory barrier before calling this to avoid getting a stale | |
70 // result. The returned result can be invalidated at any time by single- | |
71 // threaded tasks being posted or run. | |
72 bool HasSingleThreadedTasks() const; | |
robliao
2016/02/11 21:56:27
Since we're claiming this is thread safe, maybe we
fdoray
2016/02/12 04:16:20
Done.
| |
73 | |
74 // Waits until the thread exits. This must only be called after shutdown is | |
75 // complete (shutdown_manager_->shutdown_completed() returns true). This | |
76 // method is not thread-safe. | |
fdoray
2016/02/11 17:30:34
This can only be called once per WorkerThread.
robliao
2016/02/11 21:56:27
We should be able to assert this.
fdoray
2016/02/12 04:16:20
Done. I added a DCHECK, which is unfortunately not
| |
77 void JoinForTesting(); | |
78 | |
79 const PriorityQueue* shared_priority_queue() const { | |
80 return shared_priority_queue_; | |
81 } | |
82 | |
83 private: | |
84 WorkerThread(ThreadPriority thread_priority, | |
85 PriorityQueue* shared_priority_queue, | |
86 const ReinsertSequenceCallback& reinsert_sequence_callback, | |
87 const BecomesIdleCallback& becomes_idle_callback, | |
88 DelayedTaskManager* delayed_task_manager, | |
89 ShutdownManager* shutdown_manager); | |
90 | |
91 // Returns true if a thread has been successfully created by the constructor. | |
92 bool IsValid() const; | |
93 | |
94 // Extracts the sequence with the highest priority from | |
95 // |shared_priority_queue_| or |single_thread_priority_queue_|. | |
96 scoped_refptr<Sequence> GetWork(); | |
97 | |
98 // Reinserts |sequence| in |single_thread_priority_queue_|. | |
99 void ReinsertSequenceInSingleThreadPriorityQueue( | |
100 scoped_refptr<Sequence> sequence); | |
101 | |
102 // Waits until either |wakeup_event_| is signaled or a task from | |
103 // |delayed_task_manager_| becomes ready for execution. | |
104 void WaitUntilWorkIsAvailable(); | |
105 | |
106 // PlatformThread::Delegate: | |
107 void ThreadMain() override; | |
108 | |
109 // Platform thread managed by this object. | |
110 PlatformThreadHandle thread_handle_; | |
111 | |
112 // Event signaled to wake up the thread. | |
113 mutable WaitableEvent wakeup_event_; | |
114 | |
115 // True when the worker thread is running a single-threaded task. | |
116 bool is_running_single_threaded_task_; | |
117 | |
118 // The single-threaded priority queue from which the worker thread gets work. | |
119 // Tasks posted to a SINGLE_THREADED* task runner returned by this | |
120 // WorkerThread end up in this priority queue. | |
121 PriorityQueue single_thread_priority_queue_; | |
122 | |
123 // The shared priority queue from which the worker thread gets work. | |
124 PriorityQueue* const shared_priority_queue_; | |
125 | |
126 const ReinsertSequenceCallback reinsert_sequence_callback_; | |
127 | |
128 const BecomesIdleCallback becomes_idle_callback_; | |
129 | |
130 DelayedTaskManager* const delayed_task_manager_; | |
131 | |
132 ShutdownManager* const shutdown_manager_; | |
133 | |
134 DISALLOW_COPY_AND_ASSIGN(WorkerThread); | |
135 }; | |
136 | |
137 } // namespace task_scheduler | |
138 } // namespace base | |
139 | |
140 #endif // BASE_TASK_SCHEDULER_WORKER_THREAD_H_ | |
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