234 lines
6.4 KiB
HTML
234 lines
6.4 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_getcancelstate_np()--Get Cancel State</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_getcancelstate_np()--Get Cancel State</h2>
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<div class="box" style="width: 60%;">
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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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int pthread_getcancelstate_np(int *cancelState);
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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_getcancelstate_np</strong>() function gets the current
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cancel <em>state</em> of the thread. Cancel state is either
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PTHREAD_CANCEL_ENABLE or PTHREAD_CANCEL_DISABLE. For more information on
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cancelability, see <a href="users_38.htm">Thread cancellation APIs</a>.</p>
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<p>When cancelability is disabled, all cancels are held pending in the target
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thread until the thread changes the cancelability. When cancelability is
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deferred, all cancels are held pending in the target thread until the thread
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changes the cancelability, calls a function that is a cancellation point, or
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calls <strong>pthread_testcancel</strong>(), thus creating a cancellation
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point. When cancelability is asynchronous, all cancels are acted upon
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immediately, interrupting the thread with its processing.</p>
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<p><strong>Notes:</strong></p>
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<ol>
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<li>Your application should not use asynchronous thread cancellation through the
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<strong>PTHREAD_CANCEL_ASYNCHRONOUS</strong> option of <strong>
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pthread_setcanceltype</strong>(). See the common user errors section of this
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document for more information.</li>
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<li>This function is not portable.</li>
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</ol>
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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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<dl>
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<dt><strong>cancelstate</strong></dt>
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<dd>(Output) Address of the variable to receive the cancel state.</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<dl>
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<dt><strong>0</strong></dt>
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<dd><strong>pthread_getcancelstate_np</strong>() was successful.</dd>
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<dt><strong>value</strong></dt>
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<dd><strong>pthread_getcancelstate_np</strong>() was not successful. <em>
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value</em> is set to indicate the error condition.</dd>
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</dl>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>pthread_getcancelstate</strong>_np() was not successful, the
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error condition returned usually indicates one of the following errors. Under
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some conditions, the value returned could indicate an error other than those
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listed here.</p>
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<dl>
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<dt><em>[EINVAL]</em></dt>
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<dd><p>The value specified for the argument is not correct.</p></dd>
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</dl>
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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_39.htm">pthread_cancel()</a>--Cancel Thread<br><br></li>
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<li><a href="users_18.htm">pthread_exit()</a>--Terminate Calling Thread<br><br></li>
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<li><a href="users_44.htm">pthread_setcancelstate()</a>--Set Cancel State<br><br></li>
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<li><a href="users_45.htm">pthread_setcanceltype()</a>--Set Cancel Type<br><br></li>
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<li><a href="users_46.htm">pthread_testcancel()</a>--Create Cancellation
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Point</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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#define _MULTI_THREADED
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#include <pthread.h>
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#include <stdio.h>
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#include <except.h>
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#include <setjmp.h>
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#include "check.h"
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void showCancelState(void);
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int threadStatus=42;
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void showCancelState(void)
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{
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int state, rc;
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rc = pthread_getcancelstate_np(&state);
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checkResults("pthread_getcancelstate_np()\n", rc);
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printf("current cancel state is %d\n", state);
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}
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void cleanupHandler2(void *p)
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{
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printf("In cancellation cleanup handler\n");
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showCancelState();
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return;
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}
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void *threadfunc(void *parm)
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{
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int rc, old;
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printf("Inside secondary thread\n");
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showCancelState();
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pthread_cleanup_push(cleanupHandler2, NULL);
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threadStatus = 0;
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printf("Calling pthread_exit() will allow cancellation "
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"cleanup handlers to run\n");
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pthread_exit(__VOID(threadStatus));
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pthread_cleanup_pop(0);
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return __VOID(-1);
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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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char c;
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void *status;
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printf("Enter Testcase - %s\n", argv[0]);
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printf("Create thread that will demonstrate pthread_getcancelstate_np()\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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rc = pthread_join(thread, &status);
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checkResults("pthread_join()\n", rc);
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if (__INT(status) != threadStatus) {
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printf("Got an unexpected return status from the thread!\n");
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exit(1);
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}
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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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Enter Testcase - QP0WTEST/TPGETCANS0
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Create thread that will demonstrate pthread_getcancelstate_np()
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Inside secondary thread
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current cancel state is 0
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Calling pthread_exit() will allow cancellation cleanup handlers to run
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In cancellation cleanup handler
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current cancel state is 1
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Main completed
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</pre>
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<hr>
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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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