1 /*
2 * Copyright 2019 The WebRTC Project Authors. All rights reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "rtc_base/task_utils/repeating_task.h"
12
13 #include "absl/functional/any_invocable.h"
14 #include "api/task_queue/pending_task_safety_flag.h"
15 #include "rtc_base/logging.h"
16
17 namespace webrtc {
18 namespace {
19
20 class RepeatingTask {
21 public:
22 RepeatingTask(TaskQueueBase* task_queue,
23 TaskQueueBase::DelayPrecision precision,
24 TimeDelta first_delay,
25 absl::AnyInvocable<TimeDelta()> task,
26 Clock* clock,
27 rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag);
28 RepeatingTask(RepeatingTask&&) = default;
29 RepeatingTask& operator=(RepeatingTask&&) = delete;
30 ~RepeatingTask() = default;
31
32 void operator()() &&;
33
34 private:
35 TaskQueueBase* const task_queue_;
36 const TaskQueueBase::DelayPrecision precision_;
37 Clock* const clock_;
38 absl::AnyInvocable<TimeDelta()> task_;
39 // This is always finite.
40 Timestamp next_run_time_ RTC_GUARDED_BY(task_queue_);
41 rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag_
42 RTC_GUARDED_BY(task_queue_);
43 };
44
RepeatingTask(TaskQueueBase * task_queue,TaskQueueBase::DelayPrecision precision,TimeDelta first_delay,absl::AnyInvocable<TimeDelta ()> task,Clock * clock,rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag)45 RepeatingTask::RepeatingTask(
46 TaskQueueBase* task_queue,
47 TaskQueueBase::DelayPrecision precision,
48 TimeDelta first_delay,
49 absl::AnyInvocable<TimeDelta()> task,
50 Clock* clock,
51 rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag)
52 : task_queue_(task_queue),
53 precision_(precision),
54 clock_(clock),
55 task_(std::move(task)),
56 next_run_time_(clock_->CurrentTime() + first_delay),
57 alive_flag_(std::move(alive_flag)) {}
58
operator ()()59 void RepeatingTask::operator()() && {
60 RTC_DCHECK_RUN_ON(task_queue_);
61 if (!alive_flag_->alive())
62 return;
63
64 webrtc_repeating_task_impl::RepeatingTaskImplDTraceProbeRun();
65 TimeDelta delay = task_();
66 RTC_DCHECK_GE(delay, TimeDelta::Zero());
67
68 // A delay of +infinity means that the task should not be run again.
69 // Alternatively, the closure might have stopped this task.
70 if (delay.IsPlusInfinity() || !alive_flag_->alive())
71 return;
72
73 TimeDelta lost_time = clock_->CurrentTime() - next_run_time_;
74 next_run_time_ += delay;
75 delay -= lost_time;
76 delay = std::max(delay, TimeDelta::Zero());
77
78 task_queue_->PostDelayedTaskWithPrecision(precision_, std::move(*this),
79 delay);
80 }
81
82 } // namespace
83
Start(TaskQueueBase * task_queue,absl::AnyInvocable<TimeDelta ()> closure,TaskQueueBase::DelayPrecision precision,Clock * clock)84 RepeatingTaskHandle RepeatingTaskHandle::Start(
85 TaskQueueBase* task_queue,
86 absl::AnyInvocable<TimeDelta()> closure,
87 TaskQueueBase::DelayPrecision precision,
88 Clock* clock) {
89 auto alive_flag = PendingTaskSafetyFlag::CreateDetached();
90 webrtc_repeating_task_impl::RepeatingTaskHandleDTraceProbeStart();
91 task_queue->PostTask(RepeatingTask(task_queue, precision, TimeDelta::Zero(),
92 std::move(closure), clock, alive_flag));
93 return RepeatingTaskHandle(std::move(alive_flag));
94 }
95
96 // DelayedStart is equivalent to Start except that the first invocation of the
97 // closure will be delayed by the given amount.
DelayedStart(TaskQueueBase * task_queue,TimeDelta first_delay,absl::AnyInvocable<TimeDelta ()> closure,TaskQueueBase::DelayPrecision precision,Clock * clock)98 RepeatingTaskHandle RepeatingTaskHandle::DelayedStart(
99 TaskQueueBase* task_queue,
100 TimeDelta first_delay,
101 absl::AnyInvocable<TimeDelta()> closure,
102 TaskQueueBase::DelayPrecision precision,
103 Clock* clock) {
104 auto alive_flag = PendingTaskSafetyFlag::CreateDetached();
105 webrtc_repeating_task_impl::RepeatingTaskHandleDTraceProbeDelayedStart();
106 task_queue->PostDelayedTaskWithPrecision(
107 precision,
108 RepeatingTask(task_queue, precision, first_delay, std::move(closure),
109 clock, alive_flag),
110 first_delay);
111 return RepeatingTaskHandle(std::move(alive_flag));
112 }
113
Stop()114 void RepeatingTaskHandle::Stop() {
115 if (repeating_task_) {
116 repeating_task_->SetNotAlive();
117 repeating_task_ = nullptr;
118 }
119 }
120
Running() const121 bool RepeatingTaskHandle::Running() const {
122 return repeating_task_ != nullptr;
123 }
124
125 namespace webrtc_repeating_task_impl {
126 // These methods are empty, but can be externally equipped with actions using
127 // dtrace.
RepeatingTaskHandleDTraceProbeStart()128 void RepeatingTaskHandleDTraceProbeStart() {}
RepeatingTaskHandleDTraceProbeDelayedStart()129 void RepeatingTaskHandleDTraceProbeDelayedStart() {}
RepeatingTaskImplDTraceProbeRun()130 void RepeatingTaskImplDTraceProbeRun() {}
131 } // namespace webrtc_repeating_task_impl
132 } // namespace webrtc
133