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5.9 KiB
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142 lines
5.9 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML>
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<HEAD>
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<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=utf-8">
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<TITLE>"PTHREAD_RWLOCK_UNLOCK"(P) manual page</TITLE>
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<META NAME="GENERATOR" CONTENT="OpenOffice.org 1.1.3 (Linux)">
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<META NAME="CREATED" CONTENT="20050505;11291100">
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</HEAD>
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<BODY LANG="en-GB" BGCOLOR="#ffffff" DIR="LTR">
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<H4>POSIX Threads for Windows – REFERENCE - <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A></H4>
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<P><A HREF="index.html">Reference Index</A></P>
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<P><A HREF="#toc">Table of Contents</A></P>
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<H2><A HREF="#toc0" NAME="sect0">Name</A></H2>
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<P>pthread_rwlock_unlock - unlock a read-write lock object
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</P>
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<H2><A HREF="#toc1" NAME="sect1">Synopsis</A></H2>
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<P><B>#include <pthread.h> </B>
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</P>
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<P>in<B>t pthread_rwlock_unlock(pthread_rwlock_t <I>*</I></B><I>rwlock</I><B>);
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</B>
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</P>
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<H2><A HREF="#toc2" NAME="sect2">Description</A></H2>
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<P>The <B>pthread_rwlock_unlock</B> function shall release a lock
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held on the read-write lock object referenced by <I>rwlock</I>.
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Results are undefined if the read-write lock <I>rwlock</I> is not
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held by the calling thread.
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</P>
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<P>If this function is called to release a read lock from the
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read-write lock object and there are other read locks currently held
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on this read-write lock object, the read-write lock object remains in
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the read locked state. If this function releases the last read lock
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for this read-write lock object, the read-write lock object shall be
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put in the unlocked state with no owners.
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</P>
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<P>If this function is called to release a write lock for this
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read-write lock object, the read-write lock object shall be put in
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the unlocked state.
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</P>
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<P><B>Pthreads-win32</B> does not prefer either writers or readers in
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acquiring the lock – all threads enter a single prioritised FIFO
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queue. While this may not be optimally efficient for some
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applications, it does ensure that one type does not starve the other.</P>
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<P>Results are undefined if any of these functions are called with an
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uninitialized read-write lock.
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</P>
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<P><B>Pthreads-w32</B> defines <B>_POSIX_READER_WRITER_LOCKS</B> in
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pthread.h as 200112L to indicate that the reader/writer routines are
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implemented and may be used.</P>
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<H2><A HREF="#toc3" NAME="sect3">Return Value</A></H2>
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<P>If successful, the <B>pthread_rwlock_unlock</B> function shall
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return zero; otherwise, an error number shall be returned to indicate
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the error.
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</P>
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<H2><A HREF="#toc4" NAME="sect4">Errors</A></H2>
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<P>The <B>pthread_rwlock_unlock</B> function may fail if:
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</P>
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<DL>
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<DT><B>EINVAL</B>
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</DT><DD>
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The value specified by <I>rwlock</I> does not refer to an
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initialized read-write lock object.
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</DD><DD STYLE="margin-left: 0cm; margin-bottom: 0.5cm">
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<BR><BR>
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</DD></DL>
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<P>
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The <B>pthread_rwlock_unlock</B> function shall not return an error
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code of [EINTR].
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</P>
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<P><I>The following sections are informative.</I>
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</P>
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<H2><A HREF="#toc5" NAME="sect5">Examples</A></H2>
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<P>None.
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</P>
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<H2><A HREF="#toc6" NAME="sect6">Application Usage</A></H2>
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<P>None.
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</P>
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<H2><A HREF="#toc7" NAME="sect7">Rationale</A></H2>
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<P>None.
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</P>
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<H2><A HREF="#toc8" NAME="sect8">Future Directions</A></H2>
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<P>None.
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</P>
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<H2><A HREF="#toc9" NAME="sect9">See Also</A></H2>
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<P><A HREF="pthread_rwlock_init.html"><B>pthread_rwlock_destroy</B>(3)</A>
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<B>,</B> <A HREF="pthread_rwlock_rdlock.html"><B>pthread_rwlock_rdlock</B>(3)</A>
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<B>,</B> <A HREF="pthread_rwlock_timedrdlock.html"><B>pthread_rwlock_timedrdlock</B>(3)</A>
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<B>,</B> <A HREF="pthread_rwlock_timedwrlock.html"><B>pthread_rwlock_timedwrlock</B>(3)</A>
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<B>,</B> <A HREF="pthread_rwlock_rdlock.html"><B>pthread_rwlock_tryrdlock</B>(3)</A>
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<B>,</B> <A HREF="pthread_rwlock_wrlock.html"><B>pthread_rwlock_trywrlock</B>(3)</A>
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<B>,</B> <A HREF="pthread_rwlock_wrlock.html"><B>pthread_rwlock_wrlock</B>(3)</A>
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, the Base Definitions volume of IEEE Std 1003.1-2001,
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<I><pthread.h></I>
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</P>
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<H2><A HREF="#toc10" NAME="sect10">Copyright</A></H2>
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<P>Portions of this text are reprinted and reproduced in electronic
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form from IEEE Std 1003.1, 2003 Edition, Standard for Information
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Technology -- Portable Operating System Interface (POSIX), The Open
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Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the
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Institute of Electrical and Electronics Engineers, Inc and The Open
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Group. In the event of any discrepancy between this version and the
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original IEEE and The Open Group Standard, the original IEEE and The
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Open Group Standard is the referee document. The original Standard
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can be obtained online at <A HREF="http://www.opengroup.org/unix/online.html">http://www.opengroup.org/unix/online.html</A>
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.
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</P>
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<P>Modified by Ross Johnson for use with <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A>.</P>
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<HR>
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<P><A NAME="toc"></A><B>Table of Contents</B></P>
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<UL>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect0" NAME="toc0">Name</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect1" NAME="toc1">Synopsis</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect2" NAME="toc2">Description</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect3" NAME="toc3">Return
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Value</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect4" NAME="toc4">Errors</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect5" NAME="toc5">Examples</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect6" NAME="toc6">Application
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Usage</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect7" NAME="toc7">Rationale</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect8" NAME="toc8">Future
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Directions</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect9" NAME="toc9">See
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Also</A>
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</P>
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<LI><P><A HREF="#sect10" NAME="toc10">Copyright</A>
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</P>
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</UL>
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</BODY>
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</HTML>
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