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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/synchronization/cancelable_event.h"
#include <errno.h>
#include <semaphore.h>
#include <tuple>
#include "base/check.h"
#include "base/dcheck_is_on.h"
#include "base/logging.h"
#include "base/notreached.h"
#include "base/posix/eintr_wrapper.h"
#include "base/time/time.h"
namespace base {
namespace {
// Translates a base::TimeDelta (relative to now) to timespec containing
// that position in time relative to unix epoch
struct timespec TimeDeltaToAbsTimeSpec(base::TimeDelta time_delta) {
struct timespec now;
clock_gettime(CLOCK_REALTIME, &now);
struct timespec offset = time_delta.ToTimeSpec();
now.tv_sec += offset.tv_sec;
now.tv_nsec += offset.tv_nsec;
if (now.tv_nsec >= Time::kNanosecondsPerSecond) {
now.tv_sec++;
now.tv_nsec -= Time::kNanosecondsPerSecond;
}
return now;
}
} // namespace
CancelableEvent::CancelableEvent() {
int result = sem_init(&native_handle_, 0, 0U);
CHECK_EQ(result, 0);
}
CancelableEvent::~CancelableEvent() {
int result = sem_destroy(&native_handle_);
CHECK_EQ(result, 0);
}
void CancelableEvent::SignalImpl() {
int result;
#if DCHECK_IS_ON()
int sem_value = 0;
result = sem_getvalue(&native_handle_, &sem_value);
CHECK_EQ(result, 0);
DCHECK_EQ(sem_value, 0);
#endif
result = sem_post(&native_handle_);
CHECK_EQ(result, 0);
}
bool CancelableEvent::CancelImpl() {
int result = sem_trywait(&native_handle_);
if (result == -1 && errno == EAGAIN) {
return false;
}
if (result == 0) {
return true;
}
PCHECK(false);
}
bool CancelableEvent::TimedWaitImpl(TimeDelta timeout) {
int result;
if (timeout.is_max()) {
result = HANDLE_EINTR(sem_wait(&native_handle_));
} else {
// Compute the time for the end of the timeout.
const struct timespec ts = TimeDeltaToAbsTimeSpec(timeout);
// Wait for semaphore to be signalled or to timeout.
result = HANDLE_EINTR(sem_timedwait(&native_handle_, &ts));
}
if (result == 0) {
return true; // The semaphore was signalled.
}
if (result == -1 && errno == ETIMEDOUT) {
// Timed out while waiting for semaphore.
return false;
}
PCHECK(false);
}
} // namespace base
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