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NAME

       pthread_once - once-only initialization

SYNOPSIS

       #include <pthread.h>

       pthread_once_t once_control = PTHREAD_ONCE_INIT;

       int  pthread_once(pthread_once_t  *once_control,  void  (*init_routine)
       (void));

DESCRIPTION

       The  purpose  of  !pthread_once!  is  to  ensure  that   a   piece   of
       initialization  code  is  executed  at  most  once.  The |once_control|
       argument points to a static or extern variable  statically  initialized
       to !PTHREAD_ONCE_INIT!.

       The  first  time  !pthread_once!  is called with a given |once_control|
       argument, it calls |init_routine| with  no  argument  and  changes  the
       value  of the |once_control| variable to record that initialization has
       been performed.  Subsequent  calls  to  !pthread_once!  with  the  same
       !once_control! argument do nothing.

RETURN VALUE

       !pthread_once! always returns 0.

ERRORS

       None.

AUTHOR

       Xavier Leroy <Xavier.Leroy@inria.fr>

                                 LinuxThreads                  PTHREAD_ONCE(3)