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PTHREAD_ONCE(3)	       FreeBSD Library Functions Manual	       PTHREAD_ONCE(3)

NAME
     pthread_once -- dynamic package initialization

LIBRARY
     Reentrant C Library (libc_r, -lc_r)
     POSIX Threads Library (libpthread,	-lpthread)
     1:1 Threading Library (libthr, -lthr)

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 first call to pthread_once() by any thread in a process, with a given
     once_control, will	call the init_routine()	with no	arguments.  Subsequent
     calls to pthread_once() with the same once_control	will not call the
     init_routine().  On return	from pthread_once(), it	is guaranteed that
     init_routine() has	completed.  The	once_control parameter is used to
     determine whether the associated initialization routine has been called.

     The function pthread_once() is not	a cancellation point.  However,	if
     init_routine() is a cancellation point and	is cancelled, the effect on
     once_control is as	if pthread_once() was never called.

     The constant PTHREAD_ONCE_INIT is defined by header <pthread.h>.

     The behavior of pthread_once() is undefined if once_control has automatic
     storage duration or is not	initialized by PTHREAD_ONCE_INIT.

RETURN VALUES
     If	successful, the	pthread_once() function	will return zero.  Otherwise
     an	error number will be returned to indicate the error.

ERRORS
     None.

STANDARDS
     The pthread_once()	function conforms to ISO/IEC 9945-1:1996
     (``POSIX.1'').

FreeBSD	10.1			 April 4, 1996			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | STANDARDS

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