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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
/*
* Copyright 2004 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 "rtc_base/event.h"
#if defined(WEBRTC_WIN)
#include <windows.h>
#elif defined(WEBRTC_POSIX)
#include <errno.h>
#include <pthread.h>
#include <sys/time.h>
#include <time.h>
#else
#error "Must define either WEBRTC_WIN or WEBRTC_POSIX."
#endif
#include "absl/types/optional.h"
#include "rtc_base/checks.h"
#include "rtc_base/synchronization/yield_policy.h"
#include "rtc_base/system/warn_current_thread_is_deadlocked.h"
#include "rtc_base/time_utils.h"
namespace rtc {
using ::webrtc::TimeDelta;
Event::Event() : Event(false, false) {}
#if defined(WEBRTC_WIN)
Event::Event(bool manual_reset, bool initially_signaled) {
event_handle_ = ::CreateEvent(nullptr, // Security attributes.
manual_reset, initially_signaled,
nullptr); // Name.
RTC_CHECK(event_handle_);
}
Event::~Event() {
CloseHandle(event_handle_);
}
void Event::Set() {
SetEvent(event_handle_);
}
void Event::Reset() {
ResetEvent(event_handle_);
}
bool Event::Wait(TimeDelta give_up_after, TimeDelta /*warn_after*/) {
ScopedYieldPolicy::YieldExecution();
const DWORD ms =
give_up_after.IsPlusInfinity()
? INFINITE
: give_up_after.RoundUpTo(webrtc::TimeDelta::Millis(1)).ms();
return (WaitForSingleObject(event_handle_, ms) == WAIT_OBJECT_0);
}
#elif defined(WEBRTC_POSIX)
// On MacOS, clock_gettime is available from version 10.12, and on
// iOS, from version 10.0. So we can't use it yet.
#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
#define USE_CLOCK_GETTIME 0
#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 0
// On Android, pthread_condattr_setclock is available from version 21. By
// default, we target a new enough version for 64-bit platforms but not for
// 32-bit platforms. For older versions, use
// pthread_cond_timedwait_monotonic_np.
#elif defined(WEBRTC_ANDROID) && (__ANDROID_API__ < 21)
#define USE_CLOCK_GETTIME 1
#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 1
#else
#define USE_CLOCK_GETTIME 1
#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 0
#endif
Event::Event(bool manual_reset, bool initially_signaled)
: is_manual_reset_(manual_reset), event_status_(initially_signaled) {
RTC_CHECK(pthread_mutex_init(&event_mutex_, nullptr) == 0);
pthread_condattr_t cond_attr;
RTC_CHECK(pthread_condattr_init(&cond_attr) == 0);
#if USE_CLOCK_GETTIME && !USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP
RTC_CHECK(pthread_condattr_setclock(&cond_attr, CLOCK_MONOTONIC) == 0);
#endif
RTC_CHECK(pthread_cond_init(&event_cond_, &cond_attr) == 0);
pthread_condattr_destroy(&cond_attr);
}
Event::~Event() {
pthread_mutex_destroy(&event_mutex_);
pthread_cond_destroy(&event_cond_);
}
void Event::Set() {
pthread_mutex_lock(&event_mutex_);
event_status_ = true;
pthread_cond_broadcast(&event_cond_);
pthread_mutex_unlock(&event_mutex_);
}
void Event::Reset() {
pthread_mutex_lock(&event_mutex_);
event_status_ = false;
pthread_mutex_unlock(&event_mutex_);
}
namespace {
timespec GetTimespec(TimeDelta duration_from_now) {
timespec ts;
// Get the current time.
#if USE_CLOCK_GETTIME
clock_gettime(CLOCK_MONOTONIC, &ts);
#else
timeval tv;
gettimeofday(&tv, nullptr);
ts.tv_sec = tv.tv_sec;
ts.tv_nsec = tv.tv_usec * kNumNanosecsPerMicrosec;
#endif
// Add the specified number of milliseconds to it.
int64_t microsecs_from_now = duration_from_now.us();
ts.tv_sec += microsecs_from_now / kNumMicrosecsPerSec;
ts.tv_nsec +=
(microsecs_from_now % kNumMicrosecsPerSec) * kNumNanosecsPerMicrosec;
// Normalize.
if (ts.tv_nsec >= kNumNanosecsPerSec) {
ts.tv_sec++;
ts.tv_nsec -= kNumNanosecsPerSec;
}
return ts;
}
} // namespace
bool Event::Wait(TimeDelta give_up_after, TimeDelta warn_after) {
// Instant when we'll log a warning message (because we've been waiting so
// long it might be a bug), but not yet give up waiting. nullopt if we
// shouldn't log a warning.
const absl::optional<timespec> warn_ts =
warn_after >= give_up_after
? absl::nullopt
: absl::make_optional(GetTimespec(warn_after));
// Instant when we'll stop waiting and return an error. nullopt if we should
// never give up.
const absl::optional<timespec> give_up_ts =
give_up_after.IsPlusInfinity()
? absl::nullopt
: absl::make_optional(GetTimespec(give_up_after));
ScopedYieldPolicy::YieldExecution();
pthread_mutex_lock(&event_mutex_);
// Wait for `event_cond_` to trigger and `event_status_` to be set, with the
// given timeout (or without a timeout if none is given).
const auto wait = [&](const absl::optional<timespec> timeout_ts) {
int error = 0;
while (!event_status_ && error == 0) {
if (timeout_ts == absl::nullopt) {
error = pthread_cond_wait(&event_cond_, &event_mutex_);
} else {
#if USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP
error = pthread_cond_timedwait_monotonic_np(&event_cond_, &event_mutex_,
&*timeout_ts);
#else
error =
pthread_cond_timedwait(&event_cond_, &event_mutex_, &*timeout_ts);
#endif
}
}
return error;
};
int error;
if (warn_ts == absl::nullopt) {
error = wait(give_up_ts);
} else {
error = wait(warn_ts);
if (error == ETIMEDOUT) {
webrtc::WarnThatTheCurrentThreadIsProbablyDeadlocked();
error = wait(give_up_ts);
}
}
// NOTE(liulk): Exactly one thread will auto-reset this event. All
// the other threads will think it's unsignaled. This seems to be
// consistent with auto-reset events in WEBRTC_WIN
if (error == 0 && !is_manual_reset_)
event_status_ = false;
pthread_mutex_unlock(&event_mutex_);
return (error == 0);
}
#endif
} // namespace rtc
|
