NAME¶
SDL_SemWaitTimeout - Lock a semaphore, but only wait up to a specified maximum
time.
SYNOPSIS¶
#include "SDL.h" #include "SDL_thread.h"
int SDL_SemWaitTimeout(
SDL_sem *sem, Uint32
timeout);
DESCRIPTION¶
SDL_SemWaitTimeout() is a varient of
SDL_SemWait with a maximum
timeout value. If the value of the semaphore pointed to by
sem is
positive (greater than zero) it will atomically decrement the semaphore value
and return 0, otherwise it will wait up to
timeout milliseconds trying
to lock the semaphore. This function is to be avoided if possible since on
some platforms it is implemented by polling the semaphore every millisecond in
a busy loop.
After
SDL_SemWaitTimeout() 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_TIMEOUT or
-1 if the timeout period was exceeded or
there was an error, respectivly.
If the semaphore was not successfully locked, the semaphore will be unchanged.
EXAMPLES¶
res = SDL_SemWaitTimeout(my_sem, WAIT_TIMEOUT_MILLISEC);
if (res == SDL_MUTEX_TIMEOUT) {
return TRY_AGAIN;
}
if (res == -1) {
return WAIT_ERROR;
}
...
SDL_SemPost(my_sem);
SEE ALSO¶
SDL_CreateSemaphore,
SDL_DestroySemaphore,
SDL_SemWait,
SDL_SemTryWait,
SDL_SemPost,
SDL_SemValue