cond_wait(3synch)                                  cond_wait(3synch)


       NAME
             cond_wait - wait on a condition variable

       SYNOPSIS
             cc [options] -Kthread file
             #include <synch.h>
             int cond_wait(cond_t *cond, mutex_t *mutex);

          Parameters
             cond    pointer to the condition variable to wait for

             mutex   pointer to a locked mutex

       DESCRIPTION
             cond_wait blocks the calling thread at the condition variable
             pointed to by cond to wait for the occurrence of a condition.
             The calling thread must lock the mutual exclusion lock (mutex)
             pointed to by mutex before calling cond_wait, otherwise the
             behavior is unpredictable.

             cond_wait automatically releases the mutex, and waits on the
             condition variable cond.  When the condition is signaled
             cond_wait reacquires the mutex and returns to the caller.  The
             wait can also be interrupted by a UNIX system signal, in which
             case mutex is reacquired, the signal handler is called, and
             cond_wait returns EINTR.

             The calling thread can resume execution when the condition is
             signaled or broadcast, or when interrupted.  The logical
             condition should be checked on return, as a return may not
             have been caused by a change in the condition.

          cond Parameter
             The condition variable denoted by cond must previously have
             been initialized (see cond_init).

          mutex Parameter
             mutex is a mutual exclusion variable protecting a shared
             resource associated with the condition represented by the
             condition variable, cond.  The calling thread must lock mutex
             before calling cond_wait, otherwise the behavior is
             unpredictable.

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


                           Copyright 1994 Novell, Inc.               Page 1

      cond_wait(3synch)                                  cond_wait(3synch)


         Errors
            If any of the following conditions is detected, cond_wait
            fails and returns the corresponding value:

            EINTR    The wait was interrupted by a UNIX system signal.

            EINVAL   Invalid argument specified.

      USAGE
            See the description of how to use condition variables under
            USAGE on cond_init(3synch).

            Because the condition can change between the time the
            condition is signaled and the mutex is re-locked, the calling
            thread must always re-check the condition upon return from
            cond_wait.

      REFERENCES
            condition(3synch), cond_broadcast(3synch),
            cond_destroy(3synch), cond_init(3synch), cond_signal(3synch),
            cond_timedwait(3synch), sema_init(3synch), sema_post(3synch),
            sema_trywait(3synch), sema_wait(3synch), synch(3synch)


























                          Copyright 1994 Novell, Inc.               Page 2