Wait until a semaphore has a positive value and then decrements it.
int SDL_SemWaitTimeout(SDL_sem *sem, Sint32 timeoutMS);| sem | the semaphore to wait on |
| timeoutMS | the length of the timeout, in milliseconds |
Returns 0 if the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in the allotted time, or a negative error code on failure; call SDL_GetError() for more information.
This function suspends the calling thread until either the semaphore pointed to by sem has a positive value, the call is interrupted by a signal or error, or the specified time has elapsed. If the call is successful it will atomically decrement the semaphore value.
This function is available since SDL 3.0.0.
SDL_atomic_t done;
SDL_sem *sem;
SDL_AtomicSet(&done, 0);
sem = SDL_CreateSemaphore(0);
.
.
Thread A:
while (!SDL_AtomicGet(&done)) {
add_data_to_queue();
SDL_SemPost(sem);
}
Thread B:
const Uint32 timeout = 1000; /* wake up every second */
while (!SDL_AtomicGet(&done)) {
if (SDL_SemWaitTimeout(sem, timeout) == 0 && data_available()) {
get_data_from_queue();
}
... do other processing
}
.
.
SDL_AtomicSet(&done, 1);
SDL_SemPost(sem);
wait_for_threads();
SDL_DestroySemaphore(sem);