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/*
* 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 <optional>
#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 webrtc {
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(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 std::optional<timespec> warn_ts =
warn_after >= give_up_after ? std::nullopt
: std::make_optional(GetTimespec(warn_after));
// Instant when we'll stop waiting and return an error. nullopt if we should
// never give up.
const std::optional<timespec> give_up_ts =
give_up_after.IsPlusInfinity()
? std::nullopt
: std::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 std::optional<timespec> timeout_ts) {
int error = 0;
while (!event_status_ && error == 0) {
if (timeout_ts == std::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 == std::nullopt) {
error = wait(give_up_ts);
} else {
error = wait(warn_ts);
if (error == ETIMEDOUT) {
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 webrtc
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