PTHREAD_BARRIER_WAIT(P) 				     POSIX Programmer's Manual					   PTHREAD_BARRIER_WAIT(P)

NAME

       pthread_barrier_wait - synchronize at a barrier (ADVANCED REALTIME THREADS)

SYNOPSIS

       #include <pthread.h>

       int pthread_barrier_wait(pthread_barrier_t *barrier);

DESCRIPTION

       The pthread_barrier_wait() function shall synchronize participating threads at the barrier referenced by barrier.  The calling thread shall
       block until the required number of threads have called pthread_barrier_wait() specifying the barrier.

       When the required number of threads have called pthread_barrier_wait() specifying the barrier, the  constant  PTHREAD_BARRIER_SERIAL_THREAD
       shall  be  returned to one unspecified thread and zero shall be returned to each of the remaining threads. At this point, the barrier shall
       be reset to the state it had as a result of the most recent pthread_barrier_init() function that referenced it.

       The constant PTHREAD_BARRIER_SERIAL_THREAD is defined in <pthread.h> and its value shall be distinct  from  any	other  value  returned	by
       pthread_barrier_wait().

       The results are undefined if this function is called with an uninitialized barrier.

       If  a signal is delivered to a thread blocked on a barrier, upon return from the signal handler the thread shall resume waiting at the bar-
       rier if the barrier wait has not completed (that is, if the required number of threads have not arrived at the barrier during the execution
       of the signal handler); otherwise, the thread shall continue as normal from the completed barrier wait. Until the thread in the signal han-
       dler returns from it, it is unspecified whether other threads may proceed past the barrier once they have all reached it.

       A thread that has blocked on a barrier shall not prevent any unblocked thread that is eligible to use the same  processing  resources  from
       eventually making forward progress in its execution.  Eligibility for processing resources shall be determined by the scheduling policy.

RETURN VALUE

       Upon  successful completion, the pthread_barrier_wait() function shall return PTHREAD_BARRIER_SERIAL_THREAD for a single (arbitrary) thread
       synchronized at the barrier and zero for each of the other threads. Otherwise, an error number shall be returned to indicate the error.

ERRORS

       The pthread_barrier_wait() function may fail if:

       EINVAL The value specified by barrier does not refer to an initialized barrier object.

       This function shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Applications using this function may be subject to priority inversion, as discussed in the Base Definitions volume of IEEE Std 1003.1-2001,
       Section 3.285, Priority Inversion.

       The pthread_barrier_wait() function is part of the Barriers option and need not be provided on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_barrier_destroy() , the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003						   PTHREAD_BARRIER_WAIT(P)