netbsd man page for pthread_once

PTHREAD_ONCE(3) 					   BSD Library Functions Manual 					   PTHREAD_ONCE(3)

NAME
     pthread_once -- dynamic package initialization

LIBRARY
     POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS
     #include <pthread.h>

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

     pthread_once_t once_control = PTHREAD_ONCE_INIT;

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.  Sub-
     sequent 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 initializes the static once synchronization control structure once_control to be used with pthread_once().
     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 function conforms to IEEE Std 1003.1-2001 (``POSIX.1'').

BSD
								   July 9, 2010 							       BSD