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authorrpj <rpj>2005-05-06 07:27:10 +0000
committerrpj <rpj>2005-05-06 07:27:10 +0000
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+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
+<HTML>
+<HEAD>
+ <META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=utf-8">
+ <TITLE>&quot;PTHREAD_SPIN_DESTROY&quot;(P) manual page</TITLE>
+ <META NAME="GENERATOR" CONTENT="OpenOffice.org 1.1.3 (Linux)">
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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_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 &lt;pthread.h&gt; </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&nbsp;Std&nbsp;1003.1-2001,
+<I>&lt;pthread.h&gt;</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>