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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_SEQUENCE_H_ | |
6 #define BASE_TASK_SCHEDULER_SEQUENCE_H_ | |
7 | |
8 #include <stddef.h> | |
9 | |
10 #include <queue> | |
11 | |
12 #include "base/base_export.h" | |
13 #include "base/macros.h" | |
14 #include "base/memory/ref_counted.h" | |
15 #include "base/memory/scoped_ptr.h" | |
16 #include "base/task_scheduler/scheduler_lock.h" | |
17 #include "base/task_scheduler/sequence_sort_key.h" | |
18 #include "base/task_scheduler/task.h" | |
19 #include "base/task_scheduler/task_traits.h" | |
20 | |
21 namespace base { | |
22 namespace internal { | |
23 | |
24 // A sequence holds tasks that must be executed in posting order. This class is | |
robliao
2016/02/19 02:33:43
Nit: Linebreak after the period here is okay.
fdoray
2016/02/19 14:12:14
Done.
| |
25 // thread-safe. | |
26 class BASE_EXPORT Sequence : public RefCountedThreadSafe<Sequence> { | |
27 public: | |
28 Sequence(); | |
29 | |
30 // Adds |task| at the end of the sequence's queue. Returns true if the | |
31 // sequence was empty before this operation. | |
32 bool PushTask(scoped_ptr<Task> task); | |
33 | |
34 // Returns the task in front of the sequence's queue, if any. | |
35 const Task* PeekTask() const; | |
36 | |
37 // Removes the task in front of the sequence's queue. Returns true if the | |
38 // sequence is empty after this operation. Cannot be called on an empty | |
39 // sequence. | |
40 bool PopTask(); | |
41 | |
42 // Returns a SequenceSortKey to use when inserting the sequence in a priority | |
43 // queue. Cannot be called on an empty sequence. | |
44 SequenceSortKey GetSortKey() const; | |
45 | |
46 private: | |
47 friend class RefCountedThreadSafe<Sequence>; | |
48 ~Sequence(); | |
49 | |
50 // Controls access to all members. | |
robliao
2016/02/19 02:33:43
Nit: Synchronizes access to all members.
fdoray
2016/02/19 14:12:14
Done.
| |
51 mutable SchedulerLock lock_; | |
52 | |
53 // Queue of tasks to execute. | |
54 std::queue<scoped_ptr<Task>> queue_; | |
55 | |
56 // Number of task priorities in the TaskPriority enum. | |
57 static const size_t kNumTaskPriorities = | |
robliao
2016/02/19 02:33:43
Shouldn't this be taken from task_traits.h?
fdoray
2016/02/19 14:12:14
Done.
| |
58 static_cast<TaskPriorityUnderlyingType>(TaskPriority::HIGHEST) + 1; | |
robliao
2016/02/19 02:33:43
This seems like something that should remain at or
fdoray
2016/02/19 14:12:14
Done.
| |
59 | |
60 // Number of tasks contained in the sequence for each priority. | |
61 size_t num_tasks_per_priority_[kNumTaskPriorities] = {}; | |
62 | |
63 DISALLOW_COPY_AND_ASSIGN(Sequence); | |
64 }; | |
65 | |
66 } // namespace internal | |
67 } // namespace base | |
68 | |
69 #endif // BASE_TASK_SCHEDULER_SEQUENCE_H_ | |
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