.TH PTHREAD_ONCE 3 LinuxThreads

.SH NAME
pthread_once \- once-only initialization

.SH SYNOPSIS
.B #include <pthread.h>

.BI "pthread_once_t " once_control " = PTHREAD_ONCE_INIT;"

.BI "int pthread_once(pthread_once_t *" once_control ", void (*" init_routine ") (void));"

.SH DESCRIPTION

The purpose of \fBpthread_once\fP is to ensure that a piece of
initialization code is executed at most once. The \fIonce_control\fP
argument points to a static or extern variable statically initialized
to \fBPTHREAD_ONCE_INIT\fP.

The first time \fBpthread_once\fP is called with a given \fIonce_control\fP
argument, it calls \fIinit_routine\fP with no argument and changes the
value of the \fIonce_control\fP variable to record that initialization has
been performed. Subsequent calls to \fBpthread_once\fP with the same
\fBonce_control\fP argument do nothing. 

.SH "RETURN VALUE"
\fBpthread_once\fP always returns 0.

.SH ERRORS
None.

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