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