mpv/osdep/semaphore.h

#ifndef MP_SEMAPHORE_H_
#define MP_SEMAPHORE_H_

#include <sys/types.h>
#include <semaphore.h>

// OSX provides non-working empty stubs, so we emulate them.
// This should be AS-safe, but cancellation issues were ignored.
// sem_getvalue() is not provided.
// sem_post() won't always correctly return an error on overflow.
// Process-shared semantics are not provided.

#ifdef __APPLE__

#define MP_SEMAPHORE_EMULATION

#include "osdep/threads.h"

#define MP_SEM_VALUE_MAX 4096

typedef struct {
    int wakeup_pipe[2];
    mp_mutex lock;
    // protected by lock
    unsigned int count;
} mp_sem_t;

int mp_sem_init(mp_sem_t *sem, int pshared, unsigned int value);
int mp_sem_wait(mp_sem_t *sem);
int mp_sem_trywait(mp_sem_t *sem);
int mp_sem_timedwait(mp_sem_t *sem, int64_t until);
int mp_sem_post(mp_sem_t *sem);
int mp_sem_destroy(mp_sem_t *sem);

#endif

#endif