PTHREAD_BARRIER(3)					   BSD Library Functions Manual 					PTHREAD_BARRIER(3)

NAME

     pthread_barrier_destroy, pthread_barrier_init, pthread_barrier_wait -- destroy, initialize or wait on a barrier object

LIBRARY

     POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS

     #include <pthread.h>

     int
     pthread_barrier_destroy(pthread_barrier_t *barrier);

     int
     pthread_barrier_init(pthread_barrier_t *barrier, const pthread_barrierattr_t *attr, unsigned count);

     int
     pthread_barrier_wait(pthread_barrier_t *barrier);

DESCRIPTION

     The pthread_barrier_init() function will initialize barrier with attributes specified in attr, or if it is NULL, with default attributes.
     The number of threads that must call pthread_barrier_wait() before any of the waiting threads can be released is specified by count.  The
     pthread_barrier_destroy() function will destroy barrier and release any resources that may have been allocated on its behalf.

     The pthread_barrier_wait() function will synchronize calling threads at barrier.  The threads will be blocked from making further progress
     until a sufficient number of threads calls this function.	The number of threads that must call it before any of them will be released is
     determined by the count argument to pthread_barrier_init().  Once the threads have been released the barrier will be reset.

IMPLEMENTATION NOTES

     In both N:M Threading Library (libkse, -lkse) and 1:1 Threading Library (libthr, -lthr) the PTHREAD_BARRIER_SERIAL_THREAD return value will
     always be returned by the last thread to reach the barrier.

RETURN VALUES

     If successful, both pthread_barrier_destroy() and pthread_barrier_init() will return zero.  Otherwise, an error number will be returned to
     indicate the error.  If the call to pthread_barrier_wait() is successful, all but one of the threads will return zero.  That one thread will
     return PTHREAD_BARRIER_SERIAL_THREAD.  Otherwise, an error number will be returned to indicate the error.

     None of these functions will return EINTR.

ERRORS

     The pthread_barrier_destroy() function will fail if:

     [EBUSY]		An attempt was made to destroy barrier while it was in use.

     The pthread_barrier_destroy() and pthread_barrier_wait() functions may fail if:

     [EINVAL]		The value specified by barrier is invalid.

     The pthread_barrier_init() function will fail if:

     [EAGAIN]		The system lacks resources, other than memory, to initialize barrier.

     [EINVAL]		The count argument is less than 1.

     [ENOMEM]		Insufficient memory to initialize barrier.

SEE ALSO

     pthread_barrierattr(3)

HISTORY

     The pthread_barrier_destroy(), pthread_barrier_init() and pthread_barrier_wait() functions first appeared in N:M Threading Library (libkse,
     -lkse) in FreeBSD 5.2, and in 1:1 Threading Library (libthr, -lthr) in FreeBSD 5.3.

BSD
								 February 19, 2004							       BSD