OLD | NEW |
---|---|
(Empty) | |
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_SCHEDULER_THREAD_POOL_H_ | |
6 #define BASE_TASK_SCHEDULER_SCHEDULER_THREAD_POOL_H_ | |
7 | |
8 #include <stddef.h> | |
9 | |
10 #include <memory> | |
11 #include <stack> | |
12 #include <vector> | |
13 | |
14 #include "base/base_export.h" | |
15 #include "base/callback.h" | |
16 #include "base/macros.h" | |
17 #include "base/memory/ref_counted.h" | |
18 #include "base/synchronization/condition_variable.h" | |
19 #include "base/task_runner.h" | |
20 #include "base/task_scheduler/priority_queue.h" | |
21 #include "base/task_scheduler/scheduler_lock.h" | |
22 #include "base/task_scheduler/scheduler_worker_thread.h" | |
23 #include "base/task_scheduler/scheduler_worker_thread_delegate.h" | |
24 #include "base/task_scheduler/sequence.h" | |
25 #include "base/task_scheduler/task_traits.h" | |
26 #include "base/threading/platform_thread.h" | |
27 | |
28 namespace base { | |
29 namespace internal { | |
30 | |
31 struct SequenceSortKey; | |
32 class TaskTracker; | |
33 | |
34 // A pool of threads that run Tasks. This class is thread-safe. | |
35 class BASE_EXPORT SchedulerThreadPool : public SchedulerWorkerThreadDelegate { | |
36 public: | |
37 // Callback invoked after a worker thread has tried to run a Task from | |
38 // |sequence| (a TaskTracker might have prevented the Task from running). | |
39 using RanTaskFromSequenceCallback = Callback<void(scoped_refptr<Sequence>)>; | |
40 | |
41 // Creates a SchedulerThreadPool with up to |max_threads| threads of priority | |
42 // |thread_priority|. |ran_task_from_sequence_callback| will be invoked after | |
43 // a thread of this thread pool tries to run a Task. |task_tracker| is used to | |
44 // handle shutdown behavior of Tasks. Returns nullptr when it's not possible | |
45 // to create a thread pool with at least one thread. | |
gab
2016/04/07 20:32:48
s/when it's not possible to/on failure to/
fdoray
2016/04/08 14:53:03
Done.
| |
46 static std::unique_ptr<SchedulerThreadPool> CreateThreadPool( | |
47 ThreadPriority thread_priority, | |
48 size_t max_threads, | |
49 const RanTaskFromSequenceCallback& ran_task_from_sequence_callback, | |
50 TaskTracker* task_tracker); | |
51 | |
52 // Destroying a SchedulerThreadPool returned by CreateThreadPool() is not | |
53 // allowed in production; it is always leaked. In tests, it can only be | |
54 // destroyed after JoinForTesting() has returned. | |
55 ~SchedulerThreadPool(); | |
56 | |
57 // Returns a TaskRunner whose PostTask invocations will result in scheduling | |
58 // Tasks with |traits| and |execution_mode| in this thread pool. | |
gab
2016/04/07 20:32:48
Does anything make sure that this STP is the right
fdoray
2016/04/08 14:53:03
It's up to the caller to decide. The mapping TaskT
| |
59 scoped_refptr<TaskRunner> CreateTaskRunnerWithTraits( | |
60 const TaskTraits& traits, | |
61 ExecutionMode execution_mode); | |
62 | |
63 // Inserts |sequence| into this thread pool's shared priority queue with | |
64 // |sequence_sort_key|. Must only be used by a worker thread to put |sequence| | |
gab
2016/04/07 20:32:48
I would assume SWT doesn't have a pointer back to
fdoray
2016/04/08 14:53:03
Currently, the stack to reinsert a Sequence in a s
| |
65 // back into a PriorityQueue after running a Task from it. | |
66 void InsertSequenceAfterTaskRan(scoped_refptr<Sequence> sequence, | |
67 const SequenceSortKey& sequence_sort_key); | |
68 | |
69 // Waits until all threads are idle. | |
70 void WaitForAllWorkerThreadsIdleForTesting(); | |
71 | |
72 // Joins all threads of this thread pool. Tasks that are already running are | |
73 // allowed to complete their execution. This can only be called once. | |
74 void JoinForTesting(); | |
75 | |
76 private: | |
77 SchedulerThreadPool( | |
78 const RanTaskFromSequenceCallback& ran_task_from_sequence_callback, | |
79 TaskTracker* task_tracker); | |
80 | |
81 void Initialize(ThreadPriority thread_priority, size_t max_threads); | |
82 | |
83 // Wakes up one thread from this thread pool if they aren't all busy. | |
gab
2016/04/07 20:32:47
How about:
// Wakes up the last thread from this
fdoray
2016/04/08 14:53:02
Done.
| |
84 void WakeUpOneThread(); | |
85 | |
86 // Adds |worker_thread| to |idle_worker_threads_stack_|. | |
87 void AddToIdleWorkerThreadsStack(SchedulerWorkerThread* worker_thread); | |
88 | |
89 // SchedulerWorkerThreadDelegate: | |
90 void OnMainEntry() override; | |
91 void OnMainExit() override; | |
92 scoped_refptr<Sequence> GetWork( | |
93 SchedulerWorkerThread* worker_thread) override; | |
94 void RanTaskFromSequence(scoped_refptr<Sequence> sequence) override; | |
95 | |
96 // PriorityQueue from which all threads of this thread pool get work. | |
97 PriorityQueue shared_priority_queue_; | |
98 | |
99 // All worker threads owned by this thread pool. This is only modified by the | |
100 // constructor. | |
gab
2016/04/07 20:32:48
I don't think this last requirement "This is only
fdoray
2016/04/08 14:53:02
Done. Without this comment, I have to hold a lock
gab
2016/04/08 17:56:00
Good point, but I think that's the right thing to
fdoray
2016/04/08 19:00:05
Ack.
| |
101 std::vector<std::unique_ptr<SchedulerWorkerThread>> worker_threads_; | |
102 | |
103 // Synchronizes access to |idle_worker_threads_stack_| and | |
104 // |idle_worker_threads_cv_|. | |
gab
2016/04/07 20:32:48
Add a comment explaining why it takes the shared P
fdoray
2016/04/08 14:53:03
Done.
| |
105 SchedulerLock idle_worker_threads_stack_lock_; | |
106 | |
107 // Stack of idle worker threads. The last worker thread that became idle is on | |
108 // top of the stack. | |
gab
2016/04/07 20:32:48
rm "The last worker thread that became idle is top
fdoray
2016/04/08 14:53:03
Done.
| |
109 std::stack<SchedulerWorkerThread*> idle_worker_threads_stack_; | |
110 | |
111 // Signaled when all worker threads become idle. | |
112 std::unique_ptr<ConditionVariable> idle_worker_threads_stack_cv_; | |
gab
2016/04/07 20:32:48
Should we brand this with "for_testing"? I was con
danakj
2016/04/07 23:08:43
+1
fdoray
2016/04/08 14:53:03
Done.
| |
113 | |
114 // Synchronizes access to |join_for_testing_returned_|. | |
115 SchedulerLock join_for_testing_returned_lock_; | |
116 | |
117 // True once JoinForTesting() has returned. | |
118 bool join_for_testing_returned_ = false; | |
119 | |
120 const RanTaskFromSequenceCallback ran_task_from_sequence_callback_; | |
121 TaskTracker* const task_tracker_; | |
122 | |
123 DISALLOW_COPY_AND_ASSIGN(SchedulerThreadPool); | |
124 }; | |
125 | |
126 // Helper for posting |task| to the provided |sequence| and |priority_queue| | |
127 // conditional on |task_tracker|. Returns true if |task| is posted. Exposed for | |
128 // testing. | |
129 bool BASE_EXPORT PostTaskHelper(std::unique_ptr<Task> task, | |
130 scoped_refptr<Sequence> sequence, | |
131 PriorityQueue* priority_queue, | |
132 TaskTracker* task_tracker); | |
133 | |
134 } // namespace internal | |
135 } // namespace base | |
136 | |
137 #endif // BASE_TASK_SCHEDULER_SCHEDULER_THREAD_POOL_H_ | |
OLD | NEW |