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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>


       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 .