59 lines
4.0 KiB
HTML
59 lines
4.0 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="I/O multiplexing—select()" />
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<meta name="abstract" content="Because asynchronous I/O provides a more efficient way to maximize your application resources, it is recommended that you use asynchronous I/O APIs rather than the select() API. However, your specific application design may allow select() to be used." />
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<meta name="description" content="Because asynchronous I/O provides a more efficient way to maximize your application resources, it is recommended that you use asynchronous I/O APIs rather than the select() API. However, your specific application design may allow select() to be used." />
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<meta name="DC.Relation" scheme="URI" content="aconcepts.htm" />
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<meta name="DC.Relation" scheme="URI" content="xnonblock.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="cmultiplex" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>I/O multiplexing—select()</title>
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</head>
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<body id="cmultiplex"><a name="cmultiplex"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">I/O multiplexing—<span class="apiname">select()</span></h1>
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<div><p>Because asynchronous I/O provides a more efficient way to maximize
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your application resources, it is recommended that you use asynchronous I/O
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APIs rather than the <span class="apiname">select()</span> API. However, your specific
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application design may allow <span class="apiname">select()</span> to be used.</p>
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<p>Like asynchronous I/O, the <span class="apiname">select()</span> function
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creates a common point to wait for multiple conditions at the same time. However, <span class="apiname">select()</span> allows
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an application to specify sets of descriptors to see if the following conditions
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exist: </p>
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<ul><li>There is data to be read.</li>
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<li>Data can be written.</li>
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<li>An exception condition is present.</li>
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</ul>
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<p>The descriptors that can be specified in each set can be socket descriptors,
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file descriptors, or any other object that is represented by a descriptor.</p>
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<p>The <span class="apiname">select()</span> function also allows the application to
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specify if it wants to wait for data to become available. The application
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can specify how long to wait. </p>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="aconcepts.htm" title="Advanced socket concepts go beyond a general discussion of what sockets are and how they work. They provide ways to design socket applications for larger and more complex networks.">Advanced socket concepts</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="xnonblock.htm" title="This sample program uses nonblocking and the select() API.">Example: Nonblocking I/O and select()</a></div>
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</div>
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</div>
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</body>
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</html>
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