193 lines
4.9 KiB
HTML
193 lines
4.9 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>pthread_self()--Get Pthread Handle</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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<!-- 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>pthread_self()--Get Pthread Handle</h2>
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<div class="box" style="width: 50%;">
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<br>
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Syntax:
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<pre>
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#include <pthread.h>
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pthread_t pthread_self(void);
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</pre>
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Service Program Name: QP0WPTHR<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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Signal Safe: 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>pthread_self</strong>() function returns the Pthread handle of
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the calling thread. The pthread_self() function does <strong>NOT</strong>
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return the integral thread of the calling thread. You must use
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<strong>pthread_getthreadid_np</strong>() to return an integral identifier for
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the thread.</p>
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<p>If your code requires the unique integer identifier for the calling thread
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often, or in a loop, the <strong>pthread_getthreadid_np</strong>() function can
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provide significant performance improvements over the combination of
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<strong>pthread_self</strong>(), and <strong>pthread_getunique_np</strong>()
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calls that provide equivalent behavior.</p>
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<p>For example:</p>
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<pre>
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pthread_id_np_t tid;
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tid = pthread_getthreadid_np();
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</pre>
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<p>is significantly faster than these calls, but provides the same
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behavior.</p>
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<pre>
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pthread_id_np_t tid;
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pthread_t self;
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self = pthread_self();
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pthread_getunique_np(&self, &tid);
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</pre>
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<p>As always, if you are calling any function too often, performance
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improvements can be gained by storing the results in a variable and or passing
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to other functions which require the results.</p>
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<br>
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<h3>Authorities and Locks</h3>
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<p>None.</p>
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<br>
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<h3>Return Value</h3>
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<dl>
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<dt><strong>pthread_t</strong></dt>
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<dd><strong>pthread_self</strong>() returns the Pthread handle of the calling
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thread.</dd>
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</dl>
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<br>
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<h3>Error Conditions</h3>
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<p>None.</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>pthread.h</strong>> header file. See <a href=
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"rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
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<li><a href="users_17.htm">pthread_equal()</a>--Compare Two Threads<br><br></li>
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<li><a href="users_22.htm">pthread_getthreadid_np()</a>--Retrieve Unique ID for
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Calling Thread<br><br></li>
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<li><a href="users_23.htm">pthread_getunique_np()</a>--Retrieve Unique ID for
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Target Thread<br><br></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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<pre>
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#include <pthread.h>
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#include <pthread.h>
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#include <stdio.h>
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#include "check.h"
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pthread_t theThread;
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void *threadfunc(void *parm)
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{
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printf("Inside secondary thread\n");
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theThread = pthread_self();
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return NULL;
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}
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int main(int argc, char **argv)
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{
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pthread_t thread;
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int rc=0;
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printf("Entering testcase\n");
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printf("Create thread using default attributes\n");
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rc = pthread_create(&thread, NULL, threadfunc, NULL);
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checkResults("pthread_create()\n", rc);
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/* sleep() is not a very robust way to wait for the thread */
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sleep(5);
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printf("Check if the thread got its thread handle\n");
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if (!pthread_equal(thread, theThread)) {
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printf("Unexpected results on pthread_equal()!\n");
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exit(1);
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}
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printf("pthread_self() returned the thread handle\n");
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printf("Main completed\n");
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return 0;
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}
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</pre>
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<p><strong>Output:</strong></p>
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<pre>
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Entering testcase
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Create thread using default attributes
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Inside secondary thread
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Check if the thread got its thread handle
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pthread_self() returned the thread handle
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Main completed
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</pre>
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<br>
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<hr>API introduced: V4R3
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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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"rzah4mst.htm">Pthread APIs</a> | <a href="aplist.htm">APIs by
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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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