See if a semaphore has a positive value and decrement it if it does.
int SDL_SemTryWait(SDL_sem *sem);
sem | the semaphore to wait on |
Returns 0 if the wait succeeds, SDL_MUTEX_TIMEDOUT
if the wait would block, or a negative error code on failure; call SDL_GetError() for more information.
This function checks to see if the semaphore pointed to by sem
has a positive value and atomically decrements the semaphore value if it does. If the semaphore doesn't have a positive value, the function immediately returns SDL_MUTEX_TIMEDOUT.
This function is available since SDL 3.0.0.
SDL_atomic_t done;
SDL_sem *sem;
0);
SDL_AtomicSet(&done, 0);
sem = SDL_CreateSemaphore(
.
.
Thread A:while (!SDL_AtomicGet(&done)) {
add_data_to_queue();
SDL_SemPost(sem);
}
Thread B:while (!SDL_AtomicGet(&done)) {
if (SDL_SemTryWait(sem) == 0 && data_available()) {
get_data_from_queue();
}do other processing
...
}
.
.1);
SDL_AtomicSet(&done,
SDL_SemPost(sem);
wait_for_threads(); SDL_DestroySemaphore(sem);