PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       pthread_barrier_destroy, pthread_barrier_init — destroy and initialize a barrier object

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_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.

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       If    an   implementation   detects   that   the   value   specified   by   the   barrier   argument   to
       pthread_barrier_destroy() does not refer to an initialized barrier object, it  is  recommended  that  the
       function should fail and report an [EINVAL] error.

       If an implementation detects that the value specified by the attr argument to pthread_barrier_init() does
       not refer to an initialized barrier attributes object, it is recommended that the  function  should  fail
       and report an [EINVAL] error.

       If    an   implementation   detects   that   the   value   specified   by   the   barrier   argument   to
       pthread_barrier_destroy() or pthread_barrier_init() refers to a barrier that is in use (for example, in a
       pthread_barrier_wait()  call)  by  another  thread,  or  detects  that the value specified by the barrier
       argument to pthread_barrier_init() refers to an already initialized barrier  object,  it  is  recommended
       that the function should fail and report an [EBUSY] error.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_barrier_wait()

       The Base Definitions volume of POSIX.1‐2008, <pthread.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications  Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .