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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // OneShotTimer and RepeatingTimer provide a simple timer API. As the names | 5 // OneShotTimer and RepeatingTimer provide a simple timer API. As the names |
6 // suggest, OneShotTimer calls you back once after a time delay expires. | 6 // suggest, OneShotTimer calls you back once after a time delay expires. |
7 // RepeatingTimer on the other hand calls you back periodically with the | 7 // RepeatingTimer on the other hand calls you back periodically with the |
8 // prescribed time interval. | 8 // prescribed time interval. |
9 // | 9 // |
10 // OneShotTimer and RepeatingTimer both cancel the timer when they go out of | 10 // OneShotTimer and RepeatingTimer both cancel the timer when they go out of |
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32 // base::RepeatingTimer timer_; | 32 // base::RepeatingTimer timer_; |
33 // }; | 33 // }; |
34 // | 34 // |
35 // Both OneShotTimer and RepeatingTimer also support a Reset method, which | 35 // Both OneShotTimer and RepeatingTimer also support a Reset method, which |
36 // allows you to easily defer the timer event until the timer delay passes once | 36 // allows you to easily defer the timer event until the timer delay passes once |
37 // again. So, in the above example, if 0.5 seconds have already passed, | 37 // again. So, in the above example, if 0.5 seconds have already passed, |
38 // calling Reset on timer_ would postpone DoStuff by another 1 second. In | 38 // calling Reset on timer_ would postpone DoStuff by another 1 second. In |
39 // other words, Reset is shorthand for calling Stop and then Start again with | 39 // other words, Reset is shorthand for calling Stop and then Start again with |
40 // the same arguments. | 40 // the same arguments. |
41 // | 41 // |
42 // NOTE: These APIs are not thread safe. Always call from the same thread. | 42 // These APIs are not thread safe. Always call from the same sequenced task |
| 43 // runner - thread or worker pool. By default the scheduled tasks will be run |
| 44 // on the same sequence that the APIs are called from, but this can be changed |
| 45 // prior to any tasks being scheduled using SetTaskRunner(). |
43 | 46 |
44 #ifndef BASE_TIMER_TIMER_H_ | 47 #ifndef BASE_TIMER_TIMER_H_ |
45 #define BASE_TIMER_TIMER_H_ | 48 #define BASE_TIMER_TIMER_H_ |
46 | 49 |
47 // IMPORTANT: If you change timer code, make sure that all tests (including | 50 // IMPORTANT: If you change timer code, make sure that all tests (including |
48 // disabled ones) from timer_unittests.cc pass locally. Some are disabled | 51 // disabled ones) from timer_unittests.cc pass locally. Some are disabled |
49 // because they're flaky on the buildbot, but when you run them locally you | 52 // because they're flaky on the buildbot, but when you run them locally you |
50 // should be able to tell the difference. | 53 // should be able to tell the difference. |
51 | 54 |
52 #include <memory> | 55 #include <memory> |
53 | 56 |
54 #include "base/base_export.h" | 57 #include "base/base_export.h" |
55 #include "base/bind.h" | 58 #include "base/bind.h" |
56 #include "base/bind_helpers.h" | 59 #include "base/bind_helpers.h" |
57 #include "base/callback.h" | 60 #include "base/callback.h" |
58 #include "base/location.h" | 61 #include "base/location.h" |
59 #include "base/macros.h" | 62 #include "base/macros.h" |
| 63 #include "base/memory/weak_ptr.h" |
| 64 #include "base/sequence_checker.h" |
60 #include "base/time/time.h" | 65 #include "base/time/time.h" |
61 | 66 |
62 namespace base { | 67 namespace base { |
63 | 68 |
64 class BaseTimerTaskInternal; | 69 class BaseTimerTaskInternal; |
65 class SingleThreadTaskRunner; | 70 class SequencedTaskRunner; |
66 class TickClock; | 71 class TickClock; |
67 | 72 |
68 //----------------------------------------------------------------------------- | 73 //----------------------------------------------------------------------------- |
69 // This class wraps MessageLoop::PostDelayedTask to manage delayed and repeating | 74 // This class wraps TaskRunner::PostDelayedTask to manage delayed and repeating |
70 // tasks. It must be destructed on the same thread that starts tasks. There are | 75 // tasks. A Timer is bound to the sequence on which it is started. To destroy it |
71 // DCHECKs in place to verify this. | 76 // on its initial sequence (shall it differ) it must first be stopped on the |
| 77 // sequence it's bound to. There are DCHECKs in place to verify this. Note: |
| 78 // Timer is sequence-affine, but may become thread-affine if coupled with a |
| 79 // thread-affine TickClock. |
72 // | 80 // |
73 class BASE_EXPORT Timer { | 81 class BASE_EXPORT Timer { |
74 public: | 82 public: |
75 // Construct a timer in repeating or one-shot mode. Start or SetTaskInfo must | 83 // Construct a timer in repeating or one-shot mode. Start must be called later |
76 // be called later to set task info. |retain_user_task| determines whether the | 84 // to set task info. |retain_user_task| determines whether the user_task is |
77 // user_task is retained or reset when it runs or stops. If |tick_clock| is | 85 // retained or reset when it runs or stops. If |tick_clock| is provided, it is |
78 // provided, it is used instead of TimeTicks::Now() to get TimeTicks when | 86 // used instead of TimeTicks::Now() to get TimeTicks when scheduling tasks. |
79 // scheduling tasks. | |
80 Timer(bool retain_user_task, bool is_repeating); | 87 Timer(bool retain_user_task, bool is_repeating); |
81 Timer(bool retain_user_task, bool is_repeating, TickClock* tick_clock); | 88 Timer(bool retain_user_task, bool is_repeating, TickClock* tick_clock); |
82 | 89 |
83 // Construct a timer with retained task info. If |tick_clock| is provided, it | 90 // Construct a timer with retained task info. If |tick_clock| is provided, it |
84 // is used instead of TimeTicks::Now() to get TimeTicks when scheduling tasks. | 91 // is used instead of TimeTicks::Now() to get TimeTicks when scheduling tasks. |
85 Timer(const tracked_objects::Location& posted_from, | 92 Timer(const tracked_objects::Location& posted_from, |
86 TimeDelta delay, | 93 TimeDelta delay, |
87 const base::Closure& user_task, | 94 const base::Closure& user_task, |
88 bool is_repeating); | 95 bool is_repeating); |
89 Timer(const tracked_objects::Location& posted_from, | 96 Timer(const tracked_objects::Location& posted_from, |
90 TimeDelta delay, | 97 TimeDelta delay, |
91 const base::Closure& user_task, | 98 const base::Closure& user_task, |
92 bool is_repeating, | 99 bool is_repeating, |
93 TickClock* tick_clock); | 100 TickClock* tick_clock); |
94 | 101 |
95 virtual ~Timer(); | 102 virtual ~Timer(); |
96 | 103 |
97 // Returns true if the timer is running (i.e., not stopped). | 104 // Returns true if the timer is running (i.e., not stopped). |
98 virtual bool IsRunning() const; | 105 virtual bool IsRunning() const; |
99 | 106 |
100 // Returns the current delay for this timer. | 107 // Returns the current delay for this timer. |
101 virtual TimeDelta GetCurrentDelay() const; | 108 virtual TimeDelta GetCurrentDelay() const; |
102 | 109 |
103 // Set the task runner on which the task should be scheduled. This method can | 110 // Set the task runner on which the task should be scheduled. This method can |
104 // only be called before any tasks have been scheduled. The task runner must | 111 // only be called while this Timer is stopped. If a TickClock is set, it must |
105 // run tasks on the same thread the timer is used on. | 112 // support being used on both the "origin sequence" for this Timer and |
106 virtual void SetTaskRunner(scoped_refptr<SingleThreadTaskRunner> task_runner); | 113 // |task_runner|. |
| 114 virtual void SetTaskRunner(scoped_refptr<SequencedTaskRunner> task_runner); |
107 | 115 |
108 // Start the timer to run at the given |delay| from now. If the timer is | 116 // Start the timer to run at the given |delay| from now. If the timer is |
109 // already running, it will be replaced to call the given |user_task|. | 117 // already running, it will be replaced to call the given |user_task|. |
110 virtual void Start(const tracked_objects::Location& posted_from, | 118 virtual void Start(const tracked_objects::Location& posted_from, |
111 TimeDelta delay, | 119 TimeDelta delay, |
112 const base::Closure& user_task); | 120 const base::Closure& user_task); |
113 | 121 |
114 // Call this method to stop and cancel the timer. It is a no-op if the timer | 122 // Call this method to stop and cancel the timer. It is a no-op if the timer |
115 // is not running. | 123 // is not running. |
116 virtual void Stop(); | 124 virtual void Stop(); |
117 | 125 |
118 // Call this method to reset the timer delay. The user_task_ must be set. If | 126 // Call this method to reset the timer delay. The user_task_ must be set. If |
119 // the timer is not running, this will start it by posting a task. | 127 // the timer is not running, this will start it by posting a task. |
120 virtual void Reset(); | 128 virtual void Reset(); |
121 | 129 |
122 const base::Closure& user_task() const { return user_task_; } | 130 const base::Closure& user_task() const { return user_task_; } |
123 const TimeTicks& desired_run_time() const { return desired_run_time_; } | 131 const TimeTicks& desired_run_time() const { return desired_run_time_; } |
124 | 132 |
125 protected: | 133 protected: |
126 // Returns the current tick count. | |
127 TimeTicks Now() const; | |
128 | |
129 // Used to initiate a new delayed task. This has the side-effect of disabling | |
130 // scheduled_task_ if it is non-null. | |
131 void SetTaskInfo(const tracked_objects::Location& posted_from, | |
132 TimeDelta delay, | |
133 const base::Closure& user_task); | |
134 | |
135 void set_user_task(const Closure& task) { user_task_ = task; } | 134 void set_user_task(const Closure& task) { user_task_ = task; } |
136 void set_desired_run_time(TimeTicks desired) { desired_run_time_ = desired; } | 135 void set_desired_run_time(TimeTicks desired) { desired_run_time_ = desired; } |
137 void set_is_running(bool running) { is_running_ = running; } | 136 void set_is_running(bool running) { is_running_ = running; } |
138 | 137 |
139 const tracked_objects::Location& posted_from() const { return posted_from_; } | 138 const tracked_objects::Location& posted_from() const { return posted_from_; } |
140 bool retain_user_task() const { return retain_user_task_; } | 139 bool retain_user_task() const { return retain_user_task_; } |
141 bool is_repeating() const { return is_repeating_; } | 140 bool is_repeating() const { return is_repeating_; } |
142 bool is_running() const { return is_running_; } | 141 bool is_running() const { return is_running_; } |
143 | 142 |
144 private: | 143 private: |
145 friend class BaseTimerTaskInternal; | |
146 | |
147 // Allocates a new scheduled_task_ and posts it on the current MessageLoop | 144 // Allocates a new scheduled_task_ and posts it on the current MessageLoop |
148 // with the given |delay|. scheduled_task_ must be NULL. scheduled_run_time_ | 145 // with the given |delay|. This Timer must not be running when this is called. |
149 // and desired_run_time_ are reset to Now() + delay. | |
150 void PostNewScheduledTask(TimeDelta delay); | 146 void PostNewScheduledTask(TimeDelta delay); |
151 | 147 |
152 // Returns the task runner on which the task should be scheduled. If the | |
153 // corresponding task_runner_ field is null, the task runner for the current | |
154 // thread is returned. | |
155 scoped_refptr<SingleThreadTaskRunner> GetTaskRunner(); | |
156 | |
157 // Disable scheduled_task_ and abandon it so that it no longer refers back to | 148 // Disable scheduled_task_ and abandon it so that it no longer refers back to |
158 // this object. | 149 // this object. |
159 void AbandonScheduledTask(); | 150 void AbandonScheduledTask(); |
160 | 151 |
161 // Called by BaseTimerTaskInternal when the MessageLoop runs it. | 152 // Called by BaseTimerTaskInternal when the MessageLoop runs it. |
162 void RunScheduledTask(); | 153 void RunScheduledTask(); |
163 | 154 |
164 // Stop running task (if any) and abandon scheduled task (if any). | 155 // A weak pointer to the BaseTimerTaskInternal associated with this Timer |
165 void StopAndAbandon() { | 156 // while it is running. It must only be used to post tasks to that |
166 Stop(); | 157 // BaseTimerTaskInternal and must not be dereferenced nor even used to check |
167 AbandonScheduledTask(); | 158 // for null on the origin task runner (|is_running_| is used instead to know |
168 } | 159 // whether there is a pending task). Note: for performance benefits it *can* |
169 | 160 // be dereferenced inline iff GetTaskRunner()->RunsTasksOnCurrentThread(). |
170 // When non-NULL, the scheduled_task_ is waiting in the MessageLoop to call | 161 WeakPtr<BaseTimerTaskInternal> scheduled_task_weak_ref_; |
171 // RunScheduledTask() at scheduled_run_time_. | |
172 BaseTimerTaskInternal* scheduled_task_; | |
173 | 162 |
174 // The task runner on which the task should be scheduled. If it is null, the | 163 // The task runner on which the task should be scheduled. If it is null, the |
175 // task runner for the current thread should be used. | 164 // task runner for the current sequence is used. |
176 scoped_refptr<SingleThreadTaskRunner> task_runner_; | 165 scoped_refptr<SequencedTaskRunner> destination_task_runner_; |
177 | 166 |
178 // Location in user code. | 167 // Location in user code. |
179 tracked_objects::Location posted_from_; | 168 tracked_objects::Location posted_from_; |
180 // Delay requested by user. | 169 // Delay requested by user. |
181 TimeDelta delay_; | 170 TimeDelta delay_; |
182 // user_task_ is what the user wants to be run at desired_run_time_. | 171 // user_task_ is what the user wants to be run at desired_run_time_. |
183 base::Closure user_task_; | 172 base::Closure user_task_; |
184 | 173 |
185 // The estimated time that the MessageLoop will run the scheduled_task_ that | 174 // The estimated time that the MessageLoop will run the scheduled_task_ that |
186 // will call RunScheduledTask(). This time can be a "zero" TimeTicks if the | 175 // will call RunScheduledTask(). This time can be a "zero" TimeTicks if the |
187 // task must be run immediately. | 176 // task must be run immediately. |
188 TimeTicks scheduled_run_time_; | 177 TimeTicks scheduled_run_time_; |
189 | 178 |
190 // The desired run time of user_task_. The user may update this at any time, | 179 // The desired run time of user_task_. The user may update this at any time, |
191 // even if their previous request has not run yet. If desired_run_time_ is | 180 // even if their previous request has not run yet. If desired_run_time_ is |
192 // greater than scheduled_run_time_, a continuation task will be posted to | 181 // greater than scheduled_run_time_, a continuation task will be posted to |
193 // wait for the remaining time. This allows us to reuse the pending task so as | 182 // wait for the remaining time. This allows us to reuse the pending task so as |
194 // not to flood the MessageLoop with orphaned tasks when the user code | 183 // not to flood the MessageLoop with orphaned tasks when the user code |
195 // excessively Stops and Starts the timer. This time can be a "zero" TimeTicks | 184 // excessively Stops and Starts the timer. This time can be a "zero" TimeTicks |
196 // if the task must be run immediately. | 185 // if the task must be run immediately. |
197 TimeTicks desired_run_time_; | 186 TimeTicks desired_run_time_; |
198 | 187 |
199 // Thread ID of current MessageLoop for verifying single-threaded usage. | 188 // Calls to the timer are not thread safe, so a checker is used detect |
200 int thread_id_; | 189 // incorrect usage in debug builds. Uses SequenceCheckerImpl to allow usage in |
| 190 // non-DCHECK logic in ~Timer(). Note that this only verifies interactions |
| 191 // with this Timer's API; tasks themselves may be scheduled to run on a |
| 192 // different sequence through SetTaskRunner(). |
| 193 SequenceCheckerImpl origin_sequence_checker_; |
201 | 194 |
202 // Repeating timers automatically post the task again before calling the task | 195 // Repeating timers automatically post the task again before calling the task |
203 // callback. | 196 // callback. |
204 const bool is_repeating_; | 197 const bool is_repeating_; |
205 | 198 |
206 // If true, hold on to the user_task_ closure object for reuse. | 199 // If true, hold on to the user_task_ closure object for reuse. |
207 const bool retain_user_task_; | 200 const bool retain_user_task_; |
208 | 201 |
209 // The tick clock used to calculate the run time for scheduled tasks. | 202 // The tick clock used to calculate the run time for scheduled tasks. |
210 TickClock* const tick_clock_; | 203 TickClock* const tick_clock_; |
211 | 204 |
212 // If true, user_task_ is scheduled to run sometime in the future. | 205 // If true, user_task_ is scheduled to run sometime in the future. |
213 bool is_running_; | 206 bool is_running_; |
214 | 207 |
| 208 WeakPtrFactory<Timer> weak_ptr_factory_; |
| 209 |
215 DISALLOW_COPY_AND_ASSIGN(Timer); | 210 DISALLOW_COPY_AND_ASSIGN(Timer); |
216 }; | 211 }; |
217 | 212 |
218 //----------------------------------------------------------------------------- | 213 //----------------------------------------------------------------------------- |
219 // This class is an implementation detail of OneShotTimer and RepeatingTimer. | 214 // This class is an implementation detail of OneShotTimer and RepeatingTimer. |
220 // Please do not use this class directly. | 215 // Please do not use this class directly. |
221 class BaseTimerMethodPointer : public Timer { | 216 class BaseTimerMethodPointer : public Timer { |
222 public: | 217 public: |
223 // This is here to work around the fact that Timer::Start is "hidden" by the | 218 // This is here to work around the fact that Timer::Start is "hidden" by the |
224 // Start definition below, rather than being overloaded. | 219 // Start definition below, rather than being overloaded. |
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257 // A simple, repeating timer. See usage notes at the top of the file. | 252 // A simple, repeating timer. See usage notes at the top of the file. |
258 class RepeatingTimer : public BaseTimerMethodPointer { | 253 class RepeatingTimer : public BaseTimerMethodPointer { |
259 public: | 254 public: |
260 RepeatingTimer() : RepeatingTimer(nullptr) {} | 255 RepeatingTimer() : RepeatingTimer(nullptr) {} |
261 explicit RepeatingTimer(TickClock* tick_clock) | 256 explicit RepeatingTimer(TickClock* tick_clock) |
262 : BaseTimerMethodPointer(REPEATING, tick_clock) {} | 257 : BaseTimerMethodPointer(REPEATING, tick_clock) {} |
263 }; | 258 }; |
264 | 259 |
265 //----------------------------------------------------------------------------- | 260 //----------------------------------------------------------------------------- |
266 // A Delay timer is like The Button from Lost. Once started, you have to keep | 261 // A Delay timer is like The Button from Lost. Once started, you have to keep |
267 // calling Reset otherwise it will call the given method in the MessageLoop | 262 // calling Reset otherwise it will call the given method on the task runner. |
268 // thread. | |
269 // | 263 // |
270 // Once created, it is inactive until Reset is called. Once |delay| seconds have | 264 // Once created, it is inactive until Reset is called. Once |delay| seconds have |
271 // passed since the last call to Reset, the callback is made. Once the callback | 265 // passed since the last call to Reset, the callback is made. Once the callback |
272 // has been made, it's inactive until Reset is called again. | 266 // has been made, it's inactive until Reset is called again. |
273 // | 267 // |
274 // If destroyed, the timeout is canceled and will not occur even if already | 268 // If destroyed, the timeout is canceled and will not occur even if already |
275 // inflight. | 269 // inflight. |
276 class DelayTimer : protected Timer { | 270 class DelayTimer : protected Timer { |
277 public: | 271 public: |
278 template <class Receiver> | 272 template <class Receiver> |
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301 // to link in MSVC. But clang-plugin does not allow inline definitions of | 295 // to link in MSVC. But clang-plugin does not allow inline definitions of |
302 // virtual methods, so the inline definition lives in the header file here | 296 // virtual methods, so the inline definition lives in the header file here |
303 // to satisfy both. | 297 // to satisfy both. |
304 inline void DelayTimer::Reset() { | 298 inline void DelayTimer::Reset() { |
305 Timer::Reset(); | 299 Timer::Reset(); |
306 } | 300 } |
307 | 301 |
308 } // namespace base | 302 } // namespace base |
309 | 303 |
310 #endif // BASE_TIMER_TIMER_H_ | 304 #endif // BASE_TIMER_TIMER_H_ |
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