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/* Copyright (C) 2022 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "semaphore.h"
#include <assert.h>
#include <limits.h>
#include <stdlib.h>
#if defined(__APPLE__)
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
#endif
#define SEM_STATUS_POSIX INT_MIN
void knot_sem_init(knot_sem_t *sem, int value)
{
assert((sem != NULL) && (value != SEM_STATUS_POSIX));
if (value < 0) {
goto nonposix;
}
int ret = sem_init(&sem->semaphore, 1, value);
if (ret == 0) {
sem->status = SEM_STATUS_POSIX;
return;
}
nonposix:
knot_sem_init_nonposix(sem, value);
}
void knot_sem_init_nonposix(knot_sem_t *sem, int value)
{
assert((sem != NULL) && (value != SEM_STATUS_POSIX));
sem->status = value;
sem->status_lock = malloc(sizeof(*sem->status_lock));
pthread_mutex_init(&sem->status_lock->mutex, NULL);
pthread_cond_init(&sem->status_lock->cond, NULL);
}
void knot_sem_reset(knot_sem_t *sem, int value)
{
assert((sem != NULL) && (value != SEM_STATUS_POSIX) && (sem->status != SEM_STATUS_POSIX));
pthread_mutex_lock(&sem->status_lock->mutex);
sem->status = value;
pthread_cond_signal(&sem->status_lock->cond);
pthread_mutex_unlock(&sem->status_lock->mutex);
}
void knot_sem_wait(knot_sem_t *sem)
{
assert(sem != NULL);
if (sem->status == SEM_STATUS_POSIX) {
int semret;
do {
semret = sem_wait(&sem->semaphore);
} while (semret != 0); // repeat wait as it might be interrupted by a signal
} else {
pthread_mutex_lock(&sem->status_lock->mutex);
while (sem->status <= 0) {
pthread_cond_wait(&sem->status_lock->cond, &sem->status_lock->mutex);
}
sem->status--;
pthread_mutex_unlock(&sem->status_lock->mutex);
}
}
void knot_sem_wait_post(knot_sem_t *sem)
{
assert((sem != NULL) && (sem->status != SEM_STATUS_POSIX));
pthread_mutex_lock(&sem->status_lock->mutex);
while (sem->status <= 0) {
pthread_cond_wait(&sem->status_lock->cond, &sem->status_lock->mutex);
}
pthread_cond_signal(&sem->status_lock->cond);
pthread_mutex_unlock(&sem->status_lock->mutex);
}
void knot_sem_get_ahead(knot_sem_t *sem)
{
assert((sem != NULL) && (sem->status != SEM_STATUS_POSIX));
pthread_mutex_lock(&sem->status_lock->mutex);
sem->status--;
pthread_mutex_unlock(&sem->status_lock->mutex);
}
void knot_sem_get_assert(knot_sem_t *sem)
{
assert((sem != NULL) && (sem->status != SEM_STATUS_POSIX));
pthread_mutex_lock(&sem->status_lock->mutex);
assert(sem->status > 0);
sem->status--;
pthread_mutex_unlock(&sem->status_lock->mutex);
}
void knot_sem_post(knot_sem_t *sem)
{
assert(sem != NULL);
if (sem->status == SEM_STATUS_POSIX) {
int semret = sem_post(&sem->semaphore);
(void)semret;
assert(semret == 0);
} else {
pthread_mutex_lock(&sem->status_lock->mutex);
sem->status++;
pthread_cond_signal(&sem->status_lock->cond);
pthread_mutex_unlock(&sem->status_lock->mutex);
}
}
void knot_sem_destroy(knot_sem_t *sem)
{
assert(sem != NULL);
knot_sem_wait(sem); // NOTE this is questionable if the initial value was > 1
if (sem->status == SEM_STATUS_POSIX) {
sem_destroy(&sem->semaphore);
} else {
pthread_cond_destroy(&sem->status_lock->cond);
pthread_mutex_destroy(&sem->status_lock->mutex);
free(sem->status_lock);
}
}
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