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
146
147
148
149
150
151
152
153
154
155
156
157
158
|
/*
* Copyright (c) 2021 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.
*/
#include "net/dcsctp/timer/timer.h"
#include <algorithm>
#include <cstdint>
#include <limits>
#include <memory>
#include <utility>
#include "absl/memory/memory.h"
#include "absl/strings/string_view.h"
#include "net/dcsctp/public/timeout.h"
#include "rtc_base/checks.h"
namespace dcsctp {
namespace {
using ::webrtc::TimeDelta;
TimeoutID MakeTimeoutId(TimerID timer_id, TimerGeneration generation) {
return TimeoutID(static_cast<uint64_t>(*timer_id) << 32 | *generation);
}
TimeDelta GetBackoffDuration(const TimerOptions& options,
TimeDelta base_duration,
int expiration_count) {
switch (options.backoff_algorithm) {
case TimerBackoffAlgorithm::kFixed:
return base_duration;
case TimerBackoffAlgorithm::kExponential: {
TimeDelta duration = base_duration;
while (expiration_count > 0 && duration < Timer::kMaxTimerDuration) {
duration = duration * 2;
--expiration_count;
if (duration > options.max_backoff_duration) {
return options.max_backoff_duration;
}
}
return TimeDelta(std::min(duration, Timer::kMaxTimerDuration));
}
}
}
} // namespace
constexpr TimeDelta Timer::kMaxTimerDuration;
Timer::Timer(TimerID id,
absl::string_view name,
OnExpired on_expired,
UnregisterHandler unregister_handler,
std::unique_ptr<Timeout> timeout,
const TimerOptions& options)
: id_(id),
name_(name),
options_(options),
on_expired_(std::move(on_expired)),
unregister_handler_(std::move(unregister_handler)),
timeout_(std::move(timeout)),
duration_(options.duration) {}
Timer::~Timer() {
Stop();
unregister_handler_();
}
void Timer::Start() {
expiration_count_ = 0;
if (!is_running()) {
is_running_ = true;
generation_ = TimerGeneration(*generation_ + 1);
timeout_->Start(DurationMs(duration_), MakeTimeoutId(id_, generation_));
} else {
// Timer was running - stop and restart it, to make it expire in `duration_`
// from now.
generation_ = TimerGeneration(*generation_ + 1);
timeout_->Restart(DurationMs(duration_), MakeTimeoutId(id_, generation_));
}
}
void Timer::Stop() {
if (is_running()) {
timeout_->Stop();
expiration_count_ = 0;
is_running_ = false;
}
}
void Timer::Trigger(TimerGeneration generation) {
if (is_running_ && generation == generation_) {
++expiration_count_;
is_running_ = false;
if (!options_.max_restarts.has_value() ||
expiration_count_ <= *options_.max_restarts) {
// The timer should still be running after this triggers. Start a new
// timer. Note that it might be very quickly restarted again, if the
// `on_expired_` callback returns a new duration.
is_running_ = true;
TimeDelta duration =
GetBackoffDuration(options_, duration_, expiration_count_);
generation_ = TimerGeneration(*generation_ + 1);
timeout_->Start(DurationMs(duration), MakeTimeoutId(id_, generation_));
}
TimeDelta new_duration = on_expired_();
RTC_DCHECK(new_duration != TimeDelta::PlusInfinity());
if (new_duration > TimeDelta::Zero() && new_duration != duration_) {
duration_ = new_duration;
if (is_running_) {
// Restart it with new duration.
timeout_->Stop();
TimeDelta duration =
GetBackoffDuration(options_, duration_, expiration_count_);
generation_ = TimerGeneration(*generation_ + 1);
timeout_->Start(DurationMs(duration), MakeTimeoutId(id_, generation_));
}
}
}
}
void TimerManager::HandleTimeout(TimeoutID timeout_id) {
TimerID timer_id(*timeout_id >> 32);
TimerGeneration generation(*timeout_id);
auto it = timers_.find(timer_id);
if (it != timers_.end()) {
it->second->Trigger(generation);
}
}
std::unique_ptr<Timer> TimerManager::CreateTimer(absl::string_view name,
Timer::OnExpired on_expired,
const TimerOptions& options) {
next_id_ = TimerID(*next_id_ + 1);
TimerID id = next_id_;
// This would overflow after 4 billion timers created, which in SCTP would be
// after 800 million reconnections on a single socket. Ensure this will never
// happen.
RTC_CHECK_NE(*id, std::numeric_limits<uint32_t>::max());
std::unique_ptr<Timeout> timeout = create_timeout_(options.precision);
RTC_CHECK(timeout != nullptr);
auto timer = absl::WrapUnique(new Timer(
id, name, std::move(on_expired), [this, id]() { timers_.erase(id); },
std::move(timeout), options));
timers_[id] = timer.get();
return timer;
}
} // namespace dcsctp
|
