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6.7 KiB
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157 lines
6.7 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_TIMEDRDLOCK"(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;11101700">
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<!-- available at http://polyglotman.sourceforge.net/ -->
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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_timedrdlock - lock a read-write lock for reading
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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> <BR></B>#include <time.h>
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</P>
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<P><B>int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict</B>
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<I>rwlock</I><B>, const struct timespec *restrict</B> <I>abs_timeout</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_timedrdlock</B> function shall apply a read
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lock to the read-write lock referenced by <I>rwlock</I> as in the
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<A HREF="pthread_rwlock_rdlock.html"><B>pthread_rwlock_rdlock</B>(3)</A>
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function. However, if the lock cannot be acquired without waiting for
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other threads to unlock the lock, this wait shall be terminated when
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the specified timeout expires. The timeout shall expire when the
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absolute time specified by <I>abs_timeout</I> passes, as measured by
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the clock on which timeouts are based (that is, when the value of
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that clock equals or exceeds <I>abs_timeout</I>), or if the absolute
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time specified by <I>abs_timeout</I> has already been passed at the
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time of the call.
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</P>
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<P>The <B>timespec</B> data type is defined in the <I><time.h></I>
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header. Under no circumstances shall the function fail with a timeout
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if the lock can be acquired immediately. The validity of the
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<I>abs_timeout</I> parameter need not be checked if the lock can be
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immediately acquired.
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</P>
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<P>The calling thread may deadlock if at the time the call is made it
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holds a write lock on <I>rwlock</I>. The results are undefined if
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this function is called with an 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>The <B>pthread_rwlock_timedrdlock</B> function shall return zero
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if the lock for reading on the read-write lock object referenced by
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<I>rwlock</I> is acquired. Otherwise, an error number shall be
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returned to indicate 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_timedrdlock</B> function shall fail if:
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</P>
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<DL>
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<DT><B>ETIMEDOUT</B>
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</DT><DD STYLE="margin-bottom: 0.5cm">
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The lock could not be acquired before the specified timeout expired.
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</DD></DL>
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<P>
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The <B>pthread_rwlock_timedrdlock</B> function may fail if:
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</P>
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<DL>
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<DT><B>EAGAIN</B>
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</DT><DD>
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The read lock could not be acquired because the maximum number of
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read locks for lock would be exceeded.
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</DD><DT>
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<B>EINVAL</B>
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</DT><DD STYLE="margin-bottom: 0.5cm">
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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, or the <I>abs_timeout</I>
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nanosecond value is less than zero or greater than or equal to 1000
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million.
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</DD></DL>
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<P>
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This function shall not return an error 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>Applications using this function may be subject to priority
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inversion, as discussed in the Base Definitions volume of
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IEEE Std 1003.1-2001, Section 3.285, Priority Inversion.
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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_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_unlock.html"><B>pthread_rwlock_unlock</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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<B>,</B> the Base Definitions volume of IEEE Std 1003.1-2001,
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<I><pthread.h></I>, <I><time.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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