sem_trywait()

Wait on a named or unnamed semaphore, but don't block

Synopsis:

#include <semaphore.h>

int sem_trywait( sem_t * sem );

Arguments:

sem

A pointer to the sem_t object for the semaphore that you want to wait on.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The sem_trywait() function decrements the semaphore if the semaphore's value is greater than zero; otherwise, the function simply returns.

Returns:

0

The semaphore was successfully decremented.

-1

The state of the semaphore is unchanged (errno is set).

Errors:

EAGAIN

The semaphore was already locked, so it couldn't be immediately locked by the sem_trywait() function.

EDEADLK

A deadlock condition was detected.

EINVAL

Invalid semaphore descriptor sem.

EINTR

A signal interrupted this function.

Classification:

POSIX 1003.1 SEM

See also:

sem_destroy(), sem_init(), sem_post(), sem_wait()