.TH PTHREAD_ONCE 3 LinuxThreads

.SH NAME
pthread_once \- once-only initialization

.SH SYNOPSIS
#include <pthread.h>

pthread_once_t once_control = PTHREAD_ONCE_INIT;

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

.SH 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. 

.SH "RETURN VALUE"
!pthread_once! always returns 0.

.SH ERRORS
None.

.SH AUTHOR
Xavier Leroy <Xavier.Leroy@inria.fr>