SDL_SemTryWait

Name

SDL_SemTryWait -- Attempt to lock a semaphore but don't suspend the thread.

Synopsis

#include "SDL.h"
#include "SDL_thread.h"

int SDL_SemTryWait(SDL_sem *sem);

Description

SDL_SemTryWait is a non-blocking variant of SDL_SemWait. If the value of the semaphore pointed to by sem is positive it will atomically decrement the semaphore value and return 0, otherwise it will return SDL_MUTEX_TIMEDOUT instead of suspending the thread.

After SDL_SemTryWait is successful, the semaphore can be released and its count atomically incremented by a successful call to SDL_SemPost.

Return Value

Returns 0 if the semaphore was successfully locked or either SDL_MUTEX_TIMEDOUT or -1 if the thread would have suspended or there was an error, respectively.`

If the semaphore was not successfully locked, the semaphore will be unchanged.

Examples

res = SDL_SemTryWait(my_sem);

if (res == SDL_MUTEX_TIMEDOUT) {
        return TRY_AGAIN;
}
if (res == -1) {
        return WAIT_ERROR;
}

...

SDL_SemPost(my_sem);

See Also

SDL_CreateSemaphore, SDL_DestroySemaphore, SDL_SemWait, SDL_SemWaitTimeout, SDL_SemPost, SDL_SemValue

SDL_SemTryWait (last edited 2008-04-17 08:18:47 by localhost)