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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. |
| 25 // This class is 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 representing the priority of the sequence. Cannot |
| 43 // be called on an empty sequence. |
| 44 SequenceSortKey GetSortKey() const; |
| 45 |
| 46 private: |
| 47 friend class RefCountedThreadSafe<Sequence>; |
| 48 ~Sequence(); |
| 49 |
| 50 // Synchronizes access to all members. |
| 51 mutable SchedulerLock lock_; |
| 52 |
| 53 // Queue of tasks to execute. |
| 54 std::queue<scoped_ptr<Task>> queue_; |
| 55 |
| 56 // Number of tasks contained in the sequence for each priority. |
| 57 size_t num_tasks_per_priority_[static_cast<int>(TaskPriority::HIGHEST) + 1] = |
| 58 {}; |
| 59 |
| 60 DISALLOW_COPY_AND_ASSIGN(Sequence); |
| 61 }; |
| 62 |
| 63 } // namespace internal |
| 64 } // namespace base |
| 65 |
| 66 #endif // BASE_TASK_SCHEDULER_SEQUENCE_H_ |
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