PTHREAD_BARRIER(3)     FreeBSD 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 *restrict 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 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.

FreeBSD 13.1-RELEASE-p6         August 17, 2018        FreeBSD 13.1-RELEASE-p6