pthread_once(3) [netbsd man page]

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

pthread_once(3C)														  pthread_once(3C)

NAME

       pthread_once - initialize dynamic package

SYNOPSIS

       cc -mt [ flag... ] file... -lpthread [ library... ]

       #include <pthread.h>
       pthread_once_t once_control = PTHREAD_ONCE_INIT;

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

       If any thread in a process with a once_control parameter makes a call to pthread_once(), the first call will summon the init_routine(), but
       subsequent calls will not. The once_control parameter determines whether  the  associated  initialization  routine  has	been  called.  The
       init_routine() is complete upon return of pthread_once().

       pthread_once()  is not a cancellation point; however, if the function init_routine() is a cancellation point and is canceled, the effect on
       once_control is the same as if pthread_once() had never been called.

       The constant PTHREAD_ONCE_INIT is defined in the <pthread.h> header.

       If once_control has automatic storage duration or is not initialized by PTHREAD_ONCE_INIT, the behavior of pthread_once() is undefined.

       Upon successful completion, pthread_once() returns 0. Otherwise, an error number is returned to indicate the error.

       EINVAL	       once_control or	init_routine is NULL.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

       attributes(5), standards(5)

       Solaris threads do not offer this functionality.

								    23 Mar 2005 						  pthread_once(3C)