NAME

       pthread_barrier_destroy,  pthread_barrier_init  -  destroy  and  initialize  a  barrier  object (ADVANCED
       REALTIME THREADS)

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 *restrict attr, unsigned count);

DESCRIPTION

       The pthread_barrier_destroy() function shall destroy the barrier referenced by barrier  and  release  any
       resources used by the barrier. The effect of subsequent use of the barrier is undefined until the barrier
       is  reinitialized  by  another call to pthread_barrier_init(). An implementation may use this function to
       set barrier to an invalid value. The results are undefined if pthread_barrier_destroy()  is  called  when
       any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.

       The  pthread_barrier_init()  function shall allocate any resources required to use the barrier referenced
       by barrier and shall initialize the barrier with attributes referenced by attr.  If  attr  is  NULL,  the
       default  barrier  attributes  shall  be  used; the effect is the same as passing the address of a default
       barrier attributes object. The results are undefined if pthread_barrier_init() is called when any  thread
       is  blocked  on the barrier (that is, has not returned from the pthread_barrier_wait() call). The results
       are undefined if a barrier is used  without  first  being  initialized.  The  results  are  undefined  if
       pthread_barrier_init() is called specifying an already initialized barrier.

       The  count  argument  specifies the number of threads that must call pthread_barrier_wait() before any of
       them successfully return from the call.  The value specified by count must be greater than zero.

       If the pthread_barrier_init() function fails, the barrier shall not be initialized and  the  contents  of
       barrier are undefined.

       Only the object referenced by barrier may be used for performing synchronization. The result of referring
       to copies of that object in calls to pthread_barrier_destroy() or pthread_barrier_wait() is undefined.

RETURN VALUE

       Upon  successful  completion,  these  functions  shall  return  zero; otherwise, an error number shall be
       returned to indicate the error.

ERRORS

       The pthread_barrier_destroy() function may fail if:

       EBUSY  The implementation has detected an attempt to destroy a barrier while it is in use  (for  example,
              while being used in a pthread_barrier_wait() call) by another thread.

       EINVAL The value specified by barrier is invalid.

       The pthread_barrier_init() function shall fail if:

       EAGAIN The system lacks the necessary resources to initialize another barrier.

       EINVAL The value specified by count is equal to zero.

       ENOMEM Insufficient memory exists to initialize the barrier.

       The pthread_barrier_init() function may fail if:

       EBUSY  The  implementation  has  detected  an  attempt  to reinitialize a barrier while it is in use (for
              example, while being used in a pthread_barrier_wait() call) by another thread.

       EINVAL The value specified by attr is invalid.

       These functions shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The pthread_barrier_destroy() and pthread_barrier_init() functions are part of the  Barriers  option  and
       need not be provided on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_barrier_wait() , 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 Technology -- 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_DESTROY(P)