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<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_lock, pthread_spin_trylock - lock 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>int pthread_spin_lock(pthread_spinlock_t *</B><I>lock</I><B>); | |
<BR>int pthread_spin_trylock(pthread_spinlock_t *</B><I>lock</I><B>); | |
</B> | |
</P> | |
<H2><A HREF="#toc2" NAME="sect2">Description</A></H2> | |
<P>The <B>pthread_spin_lock</B> function shall lock the spin lock | |
referenced by <I>lock</I>. The calling thread shall acquire the lock | |
if it is not held by another thread. Otherwise, the thread shall spin | |
(that is, shall not return from the <B>pthread_spin_lock</B> call) | |
until the lock becomes available. The results are undefined if the | |
calling thread holds the lock at the time the call is made.</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 <A HREF="pthread_spin_init.html"><B>pthread_spin_init</B>(3)</A> | |
is called then the spin lock is initialized as a PTHREAD_MUTEX_NORMAL | |
mutex object. A thread that calls <B>pthread_spin_lock</B> 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>The <B>pthread_spin_trylock</B> function shall lock the spin lock | |
referenced by <I>lock</I> if it is not held by any thread. Otherwise, | |
the function shall fail. | |
</P> | |
<P>The results are undefined if any of these functions is called with | |
an uninitialized spin lock. | |
</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>EINVAL</B> | |
</DT><DD STYLE="margin-bottom: 0.5cm"> | |
The value specified by <I>lock</I> does not refer to an initialized | |
spin lock object. | |
</DD></DL> | |
<P> | |
The <B>pthread_spin_trylock</B> function shall fail if: | |
</P> | |
<DL> | |
<DT><B>EBUSY</B> | |
</DT><DD STYLE="margin-bottom: 0.5cm"> | |
A thread currently holds 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>Applications using this function may be subject to priority | |
inversion, as discussed in the Base Definitions volume of | |
IEEE Std 1003.1-2001, Section 3.285, Priority Inversion. | |
</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_init.html"><B>pthread_spin_destroy</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> | |
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