217 lines
5.6 KiB
HTML
217 lines
5.6 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 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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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>usleep()--Suspend Processing for Interval of Time</title>
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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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<!-- Begin Header Records ========================================== -->
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<!-- UNIX5 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Edited by Kersten Feb 02 -->
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<!-- This file has undergone error condition cleanup on 04/30/02 by JET -->
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<!--End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>usleep()--Suspend Processing for Interval of Time</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax<br>
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<pre>
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#include <unistd.h>
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unsigned int usleep( useconds_t <em>useconds</em> );
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</pre>
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<br>
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Service Program Name: QP0SSRV1<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>usleep()</strong> function suspends a thread for the number of
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microseconds specified by the of <em>useconds</em> parameter. (Because of
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processor delays, the thread can be suspended slightly longer than this
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specified time.)</p>
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<p>The <strong>usleep()</strong> function uses the process's real-time interval
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timer to indicate when the thread should be resumed.</p>
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<p>There is one real-time interval timer for each process. The <strong>
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usleep()</strong> function will not interfere with a previous setting of this
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timer.</p>
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<br>
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<!-- Please NOTE: DO NOT DELETE THIS SECTION if this API has no authorities and locks. -->
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<!-- Instead, use the commented out coding below to indicate NONE. -->
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<h3>Authorities and Locks</h3>
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<!-- Use this if there are no authorities and locks. -->
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>useconds</em></strong></dt>
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<dd>(Input) The number of microseconds for which the thread is to be
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suspended.</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<table cellpadding="5">
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<!-- cols="5 95" -->
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<tr>
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<td align="left" valign="top"><em>0</em></td>
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<td align="left" valign="top">The thread slept for the full time
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specified.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>-1</em></td>
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<td align="left" valign="top"><strong>sleep()</strong> was not successful. The
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<em>errno</em> variable is set to indicate the error.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>usleep()</strong> is not successful, <em>errno</em> usually
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indicates the following error. Under some conditions, <em>errno</em> could
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indicate an error other than that listed here.</p>
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<dl>
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<dt><em>[EINVAL]</em></dt>
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<dd>The value specified for the argument is not correct.
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<p>A function was passed incorrect argument values, or an operation was
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attempted on an object and the operation specified is not supported for that
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type of object.</p>
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<p>An argument value is not valid, out of range, or NULL.</p>
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<ul>
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<li>The time interval specified 1,000,000 or more microseconds.</li>
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</ul>
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</dd>
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</dl>
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<br>
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<h3><a name="USAGE_NOTES">Usage Notes</a></h3>
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<p>The <strong>usleep()</strong> function is included for its historical usage.
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The <strong>setitimer()</strong> function is preferred over this function.</p>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>unistd.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)<br>
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<br>
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</li>
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<li><a href="sigalarm.htm">alarm()</a>--Set Schedule for Alarm Signal<br>
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<br>
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</li>
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<li><a href="getitime.htm">getitimer()</a>--Get Value for Interval Timer<br>
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<br>
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</li>
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<li><a href="setitime.htm">setitimer()</a>--Set Value for Interval Timer<br>
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<br>
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</li>
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<li><a href="sigsleep.htm">sleep()</a>--Suspend Processing for Interval of
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Time</li>
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</ul>
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<br>
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<h3>Example</h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<p>The following example uses the <strong>usleep()</strong> function to suspend
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processing for a specified time:</p>
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<pre>
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#include <unistd.h>
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#include <stdio.h>
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#include <time.h>
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void timestamp( char *str ) {
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time_t t;
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time( &t );
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printf( "%s the time is %s\nquot;, str, ctime(&t) );
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}
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int main( int argc, char *argv[] ) {
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int result = 0;
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timestamp( quot;before usleep()quot; );
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result = usleep( 999999 );
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timestamp( quot;after usleep()quot; );
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printf( quot;usleep() returned %d\nquot;, result );
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return( result );
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}
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</pre>
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<br>
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<h3>Output:</h3>
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<pre>
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before usleep() the time is Sun Jun 15 17:25:17 1995
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after usleep() the time is Sun Jun 15 17:25:18 1995
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usleep() returned 0
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</pre>
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<br>
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<hr>
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API introduced: V4R2
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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