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| 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 | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include "base/timer.h" | |
| 6 | |
| 7 #include "base/logging.h" | |
| 8 #include "base/single_thread_task_runner.h" | |
| 9 #include "base/thread_task_runner_handle.h" | |
| 10 #include "base/threading/platform_thread.h" | |
| 11 | |
| 12 namespace base { | |
| 13 | |
| 14 // BaseTimerTaskInternal is a simple delegate for scheduling a callback to | |
| 15 // Timer in the thread's default task runner. It also handles the following | |
| 16 // edge cases: | |
| 17 // - deleted by the task runner. | |
| 18 // - abandoned (orphaned) by Timer. | |
| 19 class BaseTimerTaskInternal { | |
| 20 public: | |
| 21 explicit BaseTimerTaskInternal(Timer* timer) | |
| 22 : timer_(timer) { | |
| 23 } | |
| 24 | |
| 25 ~BaseTimerTaskInternal() { | |
| 26 // This task may be getting cleared because the task runner has been | |
| 27 // destructed. If so, don't leave Timer with a dangling pointer | |
| 28 // to this. | |
| 29 if (timer_) | |
| 30 timer_->StopAndAbandon(); | |
| 31 } | |
| 32 | |
| 33 void Run() { | |
| 34 // timer_ is NULL if we were abandoned. | |
| 35 if (!timer_) | |
| 36 return; | |
| 37 | |
| 38 // *this will be deleted by the task runner, so Timer needs to | |
| 39 // forget us: | |
| 40 timer_->scheduled_task_ = NULL; | |
| 41 | |
| 42 // Although Timer should not call back into *this, let's clear | |
| 43 // the timer_ member first to be pedantic. | |
| 44 Timer* timer = timer_; | |
| 45 timer_ = NULL; | |
| 46 timer->RunScheduledTask(); | |
| 47 } | |
| 48 | |
| 49 // The task remains in the MessageLoop queue, but nothing will happen when it | |
| 50 // runs. | |
| 51 void Abandon() { | |
| 52 timer_ = NULL; | |
| 53 } | |
| 54 | |
| 55 private: | |
| 56 Timer* timer_; | |
| 57 }; | |
| 58 | |
| 59 Timer::Timer(bool retain_user_task, bool is_repeating) | |
| 60 : scheduled_task_(NULL), | |
| 61 thread_id_(0), | |
| 62 is_repeating_(is_repeating), | |
| 63 retain_user_task_(retain_user_task), | |
| 64 is_running_(false) { | |
| 65 } | |
| 66 | |
| 67 Timer::Timer(const tracked_objects::Location& posted_from, | |
| 68 TimeDelta delay, | |
| 69 const base::Closure& user_task, | |
| 70 bool is_repeating) | |
| 71 : scheduled_task_(NULL), | |
| 72 posted_from_(posted_from), | |
| 73 delay_(delay), | |
| 74 user_task_(user_task), | |
| 75 thread_id_(0), | |
| 76 is_repeating_(is_repeating), | |
| 77 retain_user_task_(true), | |
| 78 is_running_(false) { | |
| 79 } | |
| 80 | |
| 81 Timer::~Timer() { | |
| 82 StopAndAbandon(); | |
| 83 } | |
| 84 | |
| 85 void Timer::Start(const tracked_objects::Location& posted_from, | |
| 86 TimeDelta delay, | |
| 87 const base::Closure& user_task) { | |
| 88 SetTaskInfo(posted_from, delay, user_task); | |
| 89 Reset(); | |
| 90 } | |
| 91 | |
| 92 void Timer::Stop() { | |
| 93 is_running_ = false; | |
| 94 if (!retain_user_task_) | |
| 95 user_task_.Reset(); | |
| 96 } | |
| 97 | |
| 98 void Timer::Reset() { | |
| 99 DCHECK(!user_task_.is_null()); | |
| 100 | |
| 101 // If there's no pending task, start one up and return. | |
| 102 if (!scheduled_task_) { | |
| 103 PostNewScheduledTask(delay_); | |
| 104 return; | |
| 105 } | |
| 106 | |
| 107 // Set the new desired_run_time_. | |
| 108 desired_run_time_ = TimeTicks::Now() + delay_; | |
| 109 | |
| 110 // We can use the existing scheduled task if it arrives before the new | |
| 111 // desired_run_time_. | |
| 112 if (desired_run_time_ > scheduled_run_time_) { | |
| 113 is_running_ = true; | |
| 114 return; | |
| 115 } | |
| 116 | |
| 117 // We can't reuse the scheduled_task_, so abandon it and post a new one. | |
| 118 AbandonScheduledTask(); | |
| 119 PostNewScheduledTask(delay_); | |
| 120 } | |
| 121 | |
| 122 void Timer::SetTaskInfo(const tracked_objects::Location& posted_from, | |
| 123 TimeDelta delay, | |
| 124 const base::Closure& user_task) { | |
| 125 posted_from_ = posted_from; | |
| 126 delay_ = delay; | |
| 127 user_task_ = user_task; | |
| 128 } | |
| 129 | |
| 130 void Timer::PostNewScheduledTask(TimeDelta delay) { | |
| 131 DCHECK(scheduled_task_ == NULL); | |
| 132 is_running_ = true; | |
| 133 scheduled_task_ = new BaseTimerTaskInternal(this); | |
| 134 ThreadTaskRunnerHandle::Get()->PostDelayedTask(posted_from_, | |
| 135 base::Bind(&BaseTimerTaskInternal::Run, base::Owned(scheduled_task_)), | |
| 136 delay); | |
| 137 scheduled_run_time_ = desired_run_time_ = TimeTicks::Now() + delay; | |
| 138 // Remember the thread ID that posts the first task -- this will be verified | |
| 139 // later when the task is abandoned to detect misuse from multiple threads. | |
| 140 if (!thread_id_) | |
| 141 thread_id_ = static_cast<int>(PlatformThread::CurrentId()); | |
| 142 } | |
| 143 | |
| 144 void Timer::AbandonScheduledTask() { | |
| 145 DCHECK(thread_id_ == 0 || | |
| 146 thread_id_ == static_cast<int>(PlatformThread::CurrentId())); | |
| 147 if (scheduled_task_) { | |
| 148 scheduled_task_->Abandon(); | |
| 149 scheduled_task_ = NULL; | |
| 150 } | |
| 151 } | |
| 152 | |
| 153 void Timer::RunScheduledTask() { | |
| 154 // Task may have been disabled. | |
| 155 if (!is_running_) | |
| 156 return; | |
| 157 | |
| 158 // First check if we need to delay the task because of a new target time. | |
| 159 if (desired_run_time_ > scheduled_run_time_) { | |
| 160 // TimeTicks::Now() can be expensive, so only call it if we know the user | |
| 161 // has changed the desired_run_time_. | |
| 162 TimeTicks now = TimeTicks::Now(); | |
| 163 // Task runner may have called us late anyway, so only post a continuation | |
| 164 // task if the desired_run_time_ is in the future. | |
| 165 if (desired_run_time_ > now) { | |
| 166 // Post a new task to span the remaining time. | |
| 167 PostNewScheduledTask(desired_run_time_ - now); | |
| 168 return; | |
| 169 } | |
| 170 } | |
| 171 | |
| 172 // Make a local copy of the task to run. The Stop method will reset the | |
| 173 // user_task_ member if retain_user_task_ is false. | |
| 174 base::Closure task = user_task_; | |
| 175 | |
| 176 if (is_repeating_) | |
| 177 PostNewScheduledTask(delay_); | |
| 178 else | |
| 179 Stop(); | |
| 180 | |
| 181 task.Run(); | |
| 182 | |
| 183 // No more member accesses here: *this could be deleted at this point. | |
| 184 } | |
| 185 | |
| 186 } // namespace base | |
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Chromium Code Reviews
Issue 18063004:
Move timing files into base/time, install forwarding headers. (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src