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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_DELAYED_TASK_MANAGER_H_ |
| 6 #define BASE_TASK_SCHEDULER_DELAYED_TASK_MANAGER_H_ |
| 7 |
| 8 #include <stdint.h> |
| 9 |
| 10 #include <memory> |
| 11 #include <queue> |
| 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/task_scheduler/scheduler_lock.h" |
| 19 #include "base/task_scheduler/sequence.h" |
| 20 #include "base/task_scheduler/task.h" |
| 21 #include "base/time/time.h" |
| 22 |
| 23 namespace base { |
| 24 namespace internal { |
| 25 |
| 26 class SchedulerTaskExecutor; |
| 27 |
| 28 // A DelayedTaskManager holds delayed Tasks until they become ripe for |
| 29 // execution. When they become ripe for execution, it posts them to their |
| 30 // associated Sequence and SchedulerTaskExecutor. This class is thread-safe. |
| 31 class BASE_EXPORT DelayedTaskManager { |
| 32 public: |
| 33 // |on_delayed_run_time_updated| is invoked when the delayed run time is |
| 34 // updated as a result of adding a delayed task to the manager. |
| 35 explicit DelayedTaskManager(const Closure& on_delayed_run_time_updated); |
| 36 ~DelayedTaskManager(); |
| 37 |
| 38 // Adds |task| to a queue of delayed tasks. The task will be posted to |
| 39 // |executor| as part of |sequence| the first time that PostReadyTasks() is |
| 40 // called while Now() is passed |task->delayed_run_time|. |
| 41 // |
| 42 // TODO(robliao): Find a concrete way to manage |executor|'s memory. It is |
| 43 // never deleted in production, but it is better not to spread this assumption |
| 44 // throughout the scheduler. |
| 45 void AddDelayedTask(std::unique_ptr<Task> task, |
| 46 scoped_refptr<Sequence> sequence, |
| 47 SchedulerTaskExecutor* executor); |
| 48 |
| 49 // Posts delayed tasks that are ripe for execution. |
| 50 // TODO(robliao): Call this from a service thread. |
| 51 void PostReadyTasks(); |
| 52 |
| 53 // Returns the next time at which a delayed task will become ripe for |
| 54 // execution, or a null TimeTicks if there are no pending delayed tasks. |
| 55 TimeTicks GetDelayedRunTime() const; |
| 56 |
| 57 private: |
| 58 struct DelayedTask; |
| 59 struct DelayedTaskComparator { |
| 60 bool operator()(const DelayedTask& left, const DelayedTask& right) const; |
| 61 }; |
| 62 |
| 63 // Returns the current time. Can be overridden for tests. |
| 64 virtual TimeTicks Now() const; |
| 65 |
| 66 const Closure on_delayed_run_time_updated_; |
| 67 |
| 68 // Synchronizes access to all members below. |
| 69 mutable SchedulerLock lock_; |
| 70 |
| 71 // Priority queue of delayed tasks. The delayed task with the smallest |
| 72 // |task->delayed_run_time| is in front of the priority queue. |
| 73 using DelayedTaskQueue = std::priority_queue<DelayedTask, |
| 74 std::vector<DelayedTask>, |
| 75 DelayedTaskComparator>; |
| 76 DelayedTaskQueue delayed_tasks_; |
| 77 |
| 78 // The index to assign to the next delayed task added to the manager. |
| 79 uint64_t delayed_task_index_ = 0; |
| 80 |
| 81 DISALLOW_COPY_AND_ASSIGN(DelayedTaskManager); |
| 82 }; |
| 83 |
| 84 } // namespace internal |
| 85 } // namespace base |
| 86 |
| 87 #endif // BASE_TASK_SCHEDULER_DELAYED_TASK_MANAGER_H_ |
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