sema_trywait(3synch)                            sema_trywait(3synch)


       NAME
             sema_trywait - conditionally claim resources under the
             semaphore's control

       SYNOPSIS
             cc [options] -Kthread file
             #include <synch.h>
             int sema_trywait(sema_t *sema);

          Parameters
             sema    pointer to the semaphore to acquire

       DESCRIPTION
             sema_trywait makes a single attempt to acquire the semaphore
             pointed to by sema.  If the semaphore is available,
             sema_trywait decrements the semaphore value and returns to the
             caller.

             If sema_trywait cannot immediately acquire the semaphore, it
             returns EBUSY to the caller, it does not block the caller to
             wait for the semaphore or decrement the semaphore value.

          sema Parameter
             sema must have been previously initialized, either by
             sema_init or statically (see sema_init).

          Return Values
             sema_trywait returns zero for success and an error number for
             failure, as described below.

          Errors
             If any of the following conditions occurs, sema_trywait fails
             and returns the corresponding value:

             EBUSY    The semaphore cannot be acquired immediately

             If any of the following conditions is detected, sema_trywait
             returns the corresponding value:

             EINVAL   Invalid argument specified.

       USAGE
             sema_trywait is used when the caller does not want to block if
             the semaphore is unavailable.




                           Copyright 1994 Novell, Inc.               Page 1

      sema_trywait(3synch)                            sema_trywait(3synch)


      REFERENCES
            semaphore(3synch), sema_destroy(3synch), sema_init(3synch),
            sema_post(3synch), sema_wait(3synch), synch(3synch)













































                          Copyright 1994 Novell, Inc.               Page 2