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<html><head><title>Win32::Semaphore (Perl in a Nutshell, 2nd Edition)</title><link rel="stylesheet" type="text/css" href="../style/style1.css" /><meta name="DC.Creator" content="Stephen Spainhour" /><meta name="DC.Format" content="text/xml" scheme="MIME" /><meta name="DC.Language" content="en-US" /><meta name="DC.Publisher" content="O'Reilly & Associates, Inc." /><meta name="DC.Source" scheme="ISBN" content="0596002416L" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="Perl in a Nutshell, 2nd Edition" /><meta name="DC.Type" content="Text.Monograph" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" usemap="#banner-map" border="0" alt="Book Home" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Java and XSLT" /><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch22_15.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228" /><td align="right" valign="top" width="228"><a href="ch22_17.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">22.16. Win32::Semaphore</h2><p><a name="INDEX-3367" /><a name="INDEX-3368" />The Win32::Semaphore moduleimplements semaphores, synchronizing access to shared resources. Theconstructor <tt class="literal">new</tt> creates a new semaphore object andsets the initial count and the maximum count of the semaphore. Theconstructor has the following syntax:</p><blockquote><pre class="code">$sem = Win32::Semaphore->new(<em class="replaceable"><tt>init</em>, <em class="replaceable">max</em>, [<em class="replaceable">name</tt></em>]);</pre></blockquote><p>The arguments are defined as follows:</p><dl><dt><i><em class="replaceable"><tt>init</tt></em></i></dt><dd>The initial count of the semaphore</p></dd><dt><i><em class="replaceable"><tt>max</tt></em></i></dt><dd>The maximum count of the semaphore</p></dd><dt><i><em class="replaceable"><tt>name</tt></em></i></dt><dd>A string containing a name of the semaphore</p></dd></dl><p><a name="INDEX-3369" />The <tt class="literal">open</tt> constructoropens an existing semaphore object specified by<em class="replaceable"><tt>name</tt></em>:</p><blockquote><pre class="code">$sem = Win32::Semaphore->open(<em class="replaceable"><tt>name</tt></em>);</pre></blockquote><p>The following methods can be used on Win32::Semaphore objects.</p><a name="INDEX-3370" /><a name="INDEX-3371" /><a name="INDEX-3372" /><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>release</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>$<em class="replaceable">sem</em>->release(<em class="replaceable">inc</em>, [$<em class="replaceable">var</em>])</pre><p><a name="INDEX-3370" />Releases a semaphore and increments thecount by the amount specified in <em class="replaceable"><tt>inc</tt></em>. Thelast count (before the increment) is returned in the<tt class="literal">$</tt><em class="replaceable"><tt>var</tt></em> variable, ifprovided.<a name="INDEX-3371" /><a name="INDEX-3372" /> </p></div><a name="INDEX-3373" /><div class="refentry"><table width="515" border="0" cellpadding="5"><tr><td align="left"><font size="+1"><b>wait</b></font></td><td align="right"><i></i></td></tr></table><hr width="515" size="3" noshade="true" align="left" color="black" /><pre>$<em class="replaceable">sem</em>->wait([<em class="replaceable">timeout</em>])</pre><p><a name="INDEX-3373" />The inherited Win32::IPC call. Waitsfor the semaphore's count to be nonzero, thendecrements it. Optional <em class="replaceable"><tt>timeout</tt></em> is givenin milliseconds.</p></div><hr width="684" align="left" /><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch22_15.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch22_17.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">22.15. Win32::Registry</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">22.17. Win32::Service</td></tr></table></div><hr width="684" align="left" /><img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" /><p><p><font size="-1"><a href="copyrght.htm">Copyright © 2002</a> O'Reilly & Associates. All rights reserved.</font></p><map name="library-map"><area shape="rect" coords="1,0,85,94" href="../index.htm"><area shape="rect" coords="86,1,178,103" href="../lwp/index.htm"><area shape="rect" coords="180,0,265,103" href="../lperl/index.htm"><area shape="rect" coords="267,0,353,105" href="../perlnut/index.htm"><area shape="rect" coords="354,1,446,115" href="../prog/index.htm"><area shape="rect" coords="448,0,526,132" href="../tk/index.htm"><area shape="rect" coords="528,1,615,119" href="../cookbook/index.htm"><area shape="rect" coords="617,0,690,135" href="../pxml/index.htm"></map></body></html>⌨️ 快捷键说明
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