94 lines
3.5 KiB
HTML
94 lines
3.5 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>Unsupported cancellation points</title>
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<!-- Begin Header Records ========================================== -->
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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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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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<!-- NETMG2 SCRIPT A converted by B2H R4.1 (346) (CMS) by HOLTJM at -->
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<!-- RCHVMW2 on 29 Jan 1999 at 10:01:37 -->
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<!--File Edited November 2001 -->
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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 language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>Unsupported cancellation points</h2>
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<p>i5/OS does not support the full set of cancellation points. Although the
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APIs may be provided, they are not necessarily cancellation points. The only
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cancellation points currently supported are those APIs that are part of the
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Pthread run-time. Those APIs are the following:</p>
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<ul>
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<li><strong>pthread_cond_timedwait</strong>()</li>
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<li><strong>pthread_cond_wait</strong>()</li>
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<li><strong>pthread_delay_np</strong>()</li>
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<li><strong>pthread_join</strong>()</li>
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<li><strong>pthread_join_np</strong>()</li>
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<li><strong>pthread_testcancel</strong>()</li>
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</ul>
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<p>An appropriate alternative to create cancellation points for these APIs
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might be like the following example. You can use this example to create a
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cancellation point out of any function that is asynchronous signal safe. See
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<a href="unix5a2.htm">Signal Concepts</a> for a list of functions that are
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asynchronous signal safe. If a function is not asynchronous signal safe, you
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should not use this form of asynchronous cancellation because it corrupt
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data.</p>
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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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<pre>
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... preceding code ...
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int oldtype=0;
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/* If cancellation is currently disabled, this will have no effect */
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/* if cancellation is currently enabled, we'll set it to asynchronous */
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/* for the duration of this call to try to simulate a cancellation point */
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pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldtype);
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/* Call kernel API that you want to be a cancel point. You should */
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/* only call functions which are asynchronous signal safe in this block. */
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/* Validating the asynchronous signal safety of the function will */
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/* ensure that the asynchronous cancellation does not negatively */
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/* affect the API or corrupt the data that the API uses */
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APICallHere();
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/* Restore the cancellation type that was previously in effect */
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pthread_setcanceltype(oldtype, &oldtype);
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... following code ...
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</pre>
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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">
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<a href="#Top_Of_Page">Top</a> |
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<a href="rzah4mst.htm">Pthread APIs</a> |
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<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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