1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/*
* Copyright 2019 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef RTC_BASE_TASK_UTILS_REPEATING_TASK_H_
#define RTC_BASE_TASK_UTILS_REPEATING_TASK_H_
#include <memory>
#include <type_traits>
#include <utility>
#include "api/task_queue/queued_task.h"
#include "api/task_queue/task_queue_base.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "rtc_base/task_utils/pending_task_safety_flag.h"
#include "system_wrappers/include/clock.h"
namespace webrtc {
namespace webrtc_repeating_task_impl {
class RepeatingTaskBase : public QueuedTask {
public:
RepeatingTaskBase(TaskQueueBase* task_queue,
TimeDelta first_delay,
Clock* clock,
rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag);
~RepeatingTaskBase() override;
private:
virtual TimeDelta RunClosure() = 0;
bool Run() final;
TaskQueueBase* const task_queue_;
Clock* const clock_;
// This is always finite.
Timestamp next_run_time_ RTC_GUARDED_BY(task_queue_);
rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag_
RTC_GUARDED_BY(task_queue_);
};
// The template closure pattern is based on rtc::ClosureTask.
template <class Closure>
class RepeatingTaskImpl final : public RepeatingTaskBase {
public:
RepeatingTaskImpl(TaskQueueBase* task_queue,
TimeDelta first_delay,
Closure&& closure,
Clock* clock,
rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag)
: RepeatingTaskBase(task_queue,
first_delay,
clock,
std::move(alive_flag)),
closure_(std::forward<Closure>(closure)) {
static_assert(
std::is_same<TimeDelta,
typename std::result_of<decltype (&Closure::operator())(
Closure)>::type>::value,
"");
}
private:
TimeDelta RunClosure() override { return closure_(); }
typename std::remove_const<
typename std::remove_reference<Closure>::type>::type closure_;
};
} // namespace webrtc_repeating_task_impl
// Allows starting tasks that repeat themselves on a TaskQueue indefinately
// until they are stopped or the TaskQueue is destroyed. It allows starting and
// stopping multiple times, but you must stop one task before starting another
// and it can only be stopped when in the running state. The public interface is
// not thread safe.
class RepeatingTaskHandle {
public:
RepeatingTaskHandle() = default;
~RepeatingTaskHandle() = default;
RepeatingTaskHandle(RepeatingTaskHandle&& other) = default;
RepeatingTaskHandle& operator=(RepeatingTaskHandle&& other) = default;
RepeatingTaskHandle(const RepeatingTaskHandle&) = delete;
RepeatingTaskHandle& operator=(const RepeatingTaskHandle&) = delete;
// Start can be used to start a task that will be reposted with a delay
// determined by the return value of the provided closure. The actual task is
// owned by the TaskQueue and will live until it has been stopped or the
// TaskQueue deletes it. It's perfectly fine to destroy the handle while the
// task is running, since the repeated task is owned by the TaskQueue.
template <class Closure>
static RepeatingTaskHandle Start(TaskQueueBase* task_queue,
Closure&& closure,
Clock* clock = Clock::GetRealTimeClock()) {
auto alive_flag = PendingTaskSafetyFlag::CreateDetached();
task_queue->PostTask(
std::make_unique<
webrtc_repeating_task_impl::RepeatingTaskImpl<Closure>>(
task_queue, TimeDelta::Zero(), std::forward<Closure>(closure),
clock, alive_flag));
return RepeatingTaskHandle(std::move(alive_flag));
}
// DelayedStart is equivalent to Start except that the first invocation of the
// closure will be delayed by the given amount.
template <class Closure>
static RepeatingTaskHandle DelayedStart(
TaskQueueBase* task_queue,
TimeDelta first_delay,
Closure&& closure,
Clock* clock = Clock::GetRealTimeClock()) {
auto alive_flag = PendingTaskSafetyFlag::CreateDetached();
task_queue->PostDelayedTask(
std::make_unique<
webrtc_repeating_task_impl::RepeatingTaskImpl<Closure>>(
task_queue, first_delay, std::forward<Closure>(closure), clock,
alive_flag),
first_delay.ms());
return RepeatingTaskHandle(std::move(alive_flag));
}
// Stops future invocations of the repeating task closure. Can only be called
// from the TaskQueue where the task is running. The closure is guaranteed to
// not be running after Stop() returns unless Stop() is called from the
// closure itself.
void Stop();
// Returns true until Stop() was called.
// Can only be called from the TaskQueue where the task is running.
bool Running() const;
private:
explicit RepeatingTaskHandle(
rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag)
: repeating_task_(std::move(alive_flag)) {}
rtc::scoped_refptr<PendingTaskSafetyFlag> repeating_task_;
};
} // namespace webrtc
#endif // RTC_BASE_TASK_UTILS_REPEATING_TASK_H_
|
