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+ <TITLE>PTHREAD_ONCE(3) manual page</TITLE>
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+<BODY LANG="en-GB" BGCOLOR="#ffffff" DIR="LTR">
+<H4>POSIX Threads for Windows – REFERENCE - <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A></H4>
+<P><A HREF="index.html">Reference Index</A></P>
+<P><A HREF="#toc">Table of Contents</A></P>
+<H2><A HREF="#toc0" NAME="sect0">Name</A></H2>
+<P>pthread_once - once-only initialization
+</P>
+<H2><A HREF="#toc1" NAME="sect1">Synopsis</A></H2>
+<P><B>#include &lt;pthread.h&gt;</B>
+</P>
+<P><B>pthread_once_t </B><I>once_control</I> <B>= PTHREAD_ONCE_INIT;</B>
+</P>
+<P><B>int pthread_once(pthread_once_t *</B><I>once_control</I><B>,
+void (*</B><I>init_routine</I><B>) (void));</B>
+</P>
+<H2><A HREF="#toc2" NAME="sect2">Description</A></H2>
+<P>The purpose of <B>pthread_once</B> is to ensure that a piece of
+initialization code is executed at most once. The <I>once_control</I>
+argument points to a static or extern variable statically initialized
+to <B>PTHREAD_ONCE_INIT</B>.
+</P>
+<P>The first time <B>pthread_once</B> is called with a given
+<I>once_control</I> argument, it calls <I>init_routine</I> with no
+argument and changes the value of the <I>once_control</I> variable to
+record that initialization has been performed. Subsequent calls to
+<B>pthread_once</B> with the same <B>once_control</B> argument do
+nothing.
+</P>
+<H2><A HREF="#toc3" NAME="sect3">Cancellation</A></H2>
+<P>While <B>pthread_once</B> is not a cancellation point,
+<I>init_routine</I> can be. The required effect on <I>once_control</I>
+of a cancellation inside the <I>init_routine</I> is to leave it as if
+<B>pthread_once</B> had not been called.</P>
+<P><B>Pthreads-w32</B> handles <I>init_routine</I> cancellation by
+making any threads, that may be waiting on <I>once_control</I>,
+re-compete along with any newly arriving threads in the re-running of
+<I>init_routine</I>.</P>
+<H2><A HREF="#toc4" NAME="sect4">Return Value</A></H2>
+<P STYLE="text-decoration: none"><FONT COLOR="#000000"><B>pthread_once</B>
+returns 0 on success, or an error code on failure.</FONT></P>
+<H2><A HREF="#toc5" NAME="sect5">Errors</A></H2>
+<P>The <B>pthread_once</B> function returns the following error code
+on error:
+</P>
+<DL>
+ <DL>
+ <DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B>
+ </DT></DL>
+</DL>
+<P STYLE="margin-left: 2cm">
+The once_control or init_routine parameter is NULL.</P>
+<H2><A HREF="#toc6" NAME="sect6">Author</A></H2>
+<P>Xavier Leroy &lt;Xavier.Leroy@inria.fr&gt;
+</P>
+<P>Modified by Ross Johnson for use with <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A>.</P>
+<HR>
+<P><A NAME="toc"></A><B>Table of Contents</B></P>
+<UL>
+ <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect0" NAME="toc0">Name</A>
+ </P>
+ <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect1" NAME="toc1">Synopsis</A>
+ </P>
+ <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect2" NAME="toc2">Description</A>
+ </P>
+ <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect3" NAME="toc3">Cancellation</A>
+ </P>
+ <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect4" NAME="toc4">Return
+ Value</A>
+ </P>
+ <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect5" NAME="toc5">Errors</A>
+ </P>
+ <LI><P><A HREF="#sect6" NAME="toc6">Author</A>
+ </P>
+</UL>
+</BODY>
+</HTML>