<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML> <HEAD> <META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=utf-8"> <TITLE>"PTHREAD_SPIN_DESTROY"(P) manual page</TITLE> <META NAME="GENERATOR" CONTENT="OpenOffice.org 1.1.3 (Linux)"> <META NAME="CREATED" CONTENT="20050505;12074100"> <META NAME="CHANGED" CONTENT="20050505;19014200"> <!-- manual page source format generated by PolyglotMan v3.2, --> <!-- available at http://polyglotman.sourceforge.net/ --> </HEAD> <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_spin_destroy, pthread_spin_init - destroy or initialize a spin lock object (<B>ADVANCED REALTIME THREADS</B>) </P> <H2><A HREF="#toc1" NAME="sect1">Synopsis</A></H2> <P><B>#include <pthread.h> </B> </P> <P><B>pthread_spinlock_t</B> <I>lock</I> <B>= PTHREAD_SPINLOCK_INITIALIZER;</B></P> <P><B>int pthread_spin_destroy(pthread_spinlock_t *</B><I>lock</I><B>); <BR>int pthread_spin_init(pthread_spinlock_t *</B><I>lock</I><B>, int</B> <I>pshared</I><B>); </B> </P> <H2><A HREF="#toc2" NAME="sect2">Description</A></H2> <P>The <B>pthread_spin_destroy</B> function shall destroy the spin lock referenced by <I>lock</I> and release any resources used by the lock. The effect of subsequent use of the lock is undefined until the lock is reinitialized by another call to <B>pthread_spin_init</B> . The results are undefined if <B>pthread_spin_destroy</B> is called when a thread holds the lock, or if this function is called with an uninitialized thread spin lock. </P> <P>The <B>pthread_spin_init</B> function shall allocate any resources required to use the spin lock referenced by <I>lock</I> and initialize the lock to an unlocked state. </P> <P><B>Pthreads-w32</B> supports single and multiple processor systems as well as process CPU affinity masking by checking the mask when the spin lock is initialized. If the process is using only a single processor at the time <B>pthread_spin_init</B> is called then the spin lock is initialized as a PTHREAD_MUTEX_NORMAL mutex object. A thread that calls <A HREF="pthread_spin_lock.html"><B>pthread_spin_lock(3)</B></A> will block rather than spin in this case. If the process CPU affinity mask is altered after the spin lock has been initialised, the spin lock is not modified, and may no longer be optimal for the number of CPUs available.</P> <P><B>Pthreads-w32</B> defines <B>_POSIX_THREAD_PROCESS_SHARED</B> in pthread.h as -1 to indicate that these routines do not support the <B>PTHREAD_PROCESS_SHARED</B> attribute. <B>pthread_spin_init</B> will return the error <B>ENOTSUP</B> if the value of <I>pshared</I> is not <B>PTHREAD_PROCESS_PRIVATE</B>.</P> <P>The results are undefined if <B>pthread_spin_init</B> is called specifying an already initialized spin lock. The results are undefined if a spin lock is used without first being initialized. </P> <P>If the <B>pthread_spin_init</B> function fails, the lock is not initialized and the contents of <I>lock</I> are undefined. </P> <P>Only the object referenced by <I>lock</I> may be used for performing synchronization. </P> <P>The result of referring to copies of that object in calls to <B>pthread_spin_destroy</B> , <A HREF="pthread_spin_lock.html"><B>pthread_spin_lock</B>(3)</A> , <A HREF="pthread_spin_lock.html"><B>pthread_spin_trylock</B>(3)</A>, or <A HREF="pthread_spin_unlock.html"><B>pthread_spin_unlock</B>(3)</A> is undefined. </P> <P><B>Pthreads-w32</B> supports statically initialized spin locks using <B>PTHREAD_SPINLOCK_INITIALIZER</B>. An application should still call <B>pthread_spin_destroy</B> at some point to ensure that any resources consumed by the spin lock are released.</P> <H2><A HREF="#toc3" NAME="sect3">Return Value</A></H2> <P>Upon successful completion, these functions shall return zero; otherwise, an error number shall be returned to indicate the error. </P> <H2><A HREF="#toc4" NAME="sect4">Errors</A></H2> <P>These functions may fail if: </P> <DL> <DT><B>EBUSY</B> </DT><DD> The implementation has detected an attempt to initialize or destroy a spin lock while it is in use (for example, while being used in a <A HREF="pthread_spin_lock.html"><B>pthread_spin_lock</B>(3)</A> call) by another thread. </DD><DT> <B>EINVAL</B> </DT><DD STYLE="margin-bottom: 0.5cm"> The value specified by <I>lock</I> is invalid. </DD></DL> <P> The <B>pthread_spin_init</B> function shall fail if: </P> <DL> <DT><B>ENOTSUP</B> </DT><DD> The value of <I>pshared</I> is not <B>PTHREAD_PROCESS_PRIVATE</B>.</DD><DT> <B>ENOMEM</B> </DT><DD STYLE="margin-bottom: 0.5cm"> Insufficient memory exists to initialize the lock. </DD></DL> <P> These functions shall not return an error code of [EINTR]. </P> <P><I>The following sections are informative.</I> </P> <H2><A HREF="#toc5" NAME="sect5">Examples</A></H2> <P>None. </P> <H2><A HREF="#toc6" NAME="sect6">Application Usage</A></H2> <P>The <B>pthread_spin_destroy</B> and <B>pthread_spin_init</B> functions are part of the Spin Locks option and need not be provided on all implementations. </P> <H2><A HREF="#toc7" NAME="sect7">Rationale</A></H2> <P>None. </P> <H2><A HREF="#toc8" NAME="sect8">Future Directions</A></H2> <P>None. </P> <H2><A HREF="#toc9" NAME="sect9">See Also</A></H2> <P><A HREF="pthread_spin_lock.html"><B>pthread_spin_lock</B>(3)</A> <B>,</B> <A HREF="pthread_spin_unlock.html"><B>pthread_spin_unlock</B>(3)</A> <B>,</B> the Base Definitions volume of IEEE Std 1003.1-2001, <I><pthread.h></I> </P> <H2><A HREF="#toc10" NAME="sect10">Copyright</A></H2> <P>Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at <A HREF="http://www.opengroup.org/unix/online.html">http://www.opengroup.org/unix/online.html</A> . </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">Return Value</A> </P> <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect4" NAME="toc4">Errors</A> </P> <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect5" NAME="toc5">Examples</A> </P> <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect6" NAME="toc6">Application Usage</A> </P> <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect7" NAME="toc7">Rationale</A> </P> <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect8" NAME="toc8">Future Directions</A> </P> <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect9" NAME="toc9">See Also</A> </P> <LI><P><A HREF="#sect10" NAME="toc10">Copyright</A> </P> </UL> </BODY> </HTML>