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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/>.
*/
#pragma once
#include <pthread.h>
#include <semaphore.h>
typedef struct {
pthread_mutex_t mutex;
pthread_cond_t cond;
} knot_sem_nonposix_t;
typedef struct {
int status;
union {
sem_t semaphore;
knot_sem_nonposix_t *status_lock;
};
} knot_sem_t;
/*!
* \brief Initialize semaphore by using POSIX sem_t if possible, custom value/mutex/cond structure otherwise.
*/
void knot_sem_init(knot_sem_t *sem, int value);
/*!
* \brief Initialize semaphore, force using nonposix variant.
*/
void knot_sem_init_nonposix(knot_sem_t *sem, int value);
/*!
* \brief Set semaphore value to specified value.
* \note This can be only used with nonposix semaphore.
*/
void knot_sem_reset(knot_sem_t *sem, int value);
/*!
* \brief Lock the semaphore (decrement), block until it's non-negative.
*/
void knot_sem_wait(knot_sem_t *sem);
/*!
* \brief Block until the semaphore could decrement, but keep the value unchanged.
* \note This can be only used with nonposix semaphore.
*/
void knot_sem_wait_post(knot_sem_t *sem);
/*!
* \brief Force-lock the semaphore without blocking, it might get negative.
* \note This can be only used with nonposix semaphore.
*/
void knot_sem_get_ahead(knot_sem_t *sem);
/*!
* \brief Lock the semaphore, abort() if it would block.
* \note This can be only used with nonposix semaphore.
*/
void knot_sem_get_assert(knot_sem_t *sem);
/*!
* \brief Unlock the semaphore (increment).
*/
void knot_sem_post(knot_sem_t *sem);
/*!
* \brief Uninitialize the semaphore. Calls knot_sem_wait once at the beginning.
*/
void knot_sem_destroy(knot_sem_t *sem);
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