197 lines
5.9 KiB
HTML
197 lines
5.9 KiB
HTML
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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_mutexattr_getkind_np()--Get Mutex Kind Attribute</title>
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<a name="Top_Of_Page"></a>
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<h2>pthread_mutexattr_getkind_np()--Get Mutex Kind Attribute</h2>
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<div class="box" style="width: 70%;">
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<br>
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Syntax:
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<pre> #include <pthread.h>
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int pthread_mutexattr_getkind_np(const pthread_mutexattr_t *attr,
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int *kind);</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_mutexattr_getkind_np</strong>() function retrieves the <em>kind</em> attribute from the mutex attributes object specified by <em>attr</em>. The mutex kind attribute is used to create mutexes with different behaviors.</p>
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<p>The <em>kind</em> returned is one of <strong>PTHREAD_MUTEX_NONRECURSIVE_NP</strong> or <strong>PTHREAD_MUTEX_RECURSIVE_NP</strong>.</p>
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<p>A recursive mutex can be locked repeatedly by the owner. The mutex does not become unlocked until the owner has called <strong>pthread_mutex_unlock</strong>() for each successful lock request that it has outstanding on the mutes.</p>
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<p><strong>Note:</strong> This function is not portable.</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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<dl>
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<dt><strong>attr</strong></dt>
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<dd>(Input) Address of the mutex attributes object</dd>
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<dt><strong>kind</strong></dt>
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<dd>(Output) Address of the variable to receive the <em>kind</em> attribute</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_mutexattr_getkind_np</strong>() was successful.</dd>
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<dt><strong>value</strong></dt>
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<dd><strong>pthread_mutexattr_getkind_np</strong>() was not successful. <em>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_mutexattr_getkind_np</strong>() was not successful, the error condition returned usually indicates one of the following errors. Under some conditions, the value returned could indicate an error other than those 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="rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
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<li><a href="users_54.htm">pthread_mutexattr_init()</a>--Initialize Mutex Attributes Object<br><br></li>
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<li><a href="users_55.htm">pthread_mutexattr_setkind_np()</a>--Set Mutex Kind Attribute<br><br></li>
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<li> <a href="users_61.htm">pthread_mutex_init()</a>--Initialize Mutex</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>#include <pthread.h>
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#include <stdio.h>
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#include "check.h"
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void showKind(pthread_mutexattr_t *mta) {
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int rc;
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int kind;
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printf("Check kind attribute\n");
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rc = pthread_mutexattr_getkind_np(mta, &kind);
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checkResults("pthread_mutexattr_getpshared()\n", rc);
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printf("The pshared attributed is: ");
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switch (kind) {
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case PTHREAD_MUTEX_NONRECURSIVE_NP:
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printf("PTHREAD_MUTEX_NONRECURSIVE_NP\n");
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break;
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case PTHREAD_MUTEX_RECURSIVE_NP:
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printf("PTHREAD_MUTEX_RECURSIVE_NP\n");
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break;
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default :
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printf("! kind Error kind=%d !\n", kind);
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exit(1);
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}
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return;
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}
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int main(int argc, char **argv)
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{
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int rc=0;
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pthread_mutexattr_t mta;
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int pshared=0;
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printf("Enter Testcase - %s\n", argv[0]);
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printf("Create a default mutex attribute\n");
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rc = pthread_mutexattr_init(&mta);
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checkResults("pthread_mutexattr_init()\n", rc);
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showKind(&mta);
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printf("Change mutex kind attribute\n");
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rc = pthread_mutexattr_setkind_np(&mta, PTHREAD_MUTEX_RECURSIVE_NP);
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checkResults("pthread_mutexattr_setkind()\n", rc);
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showKind(&mta);
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printf("Destroy mutex attribute\n");
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rc = pthread_mutexattr_destroy(&mta);
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checkResults("pthread_mutexattr_destroy()\n", rc);
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printf("Main completed\n");
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return 0;
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}</pre>
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<p><strong>Output:</strong></p>
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<pre>Enter Testcase - QP0WTEST/TPMTXAKN0
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Create a default mutex attribute
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Check kind attribute
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The pshared attributed is:
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PTHREAD_MUTEX_NONRECURSIVE_NP
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Change mutex kind attribute
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Check kind attribute
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The pshared attributed is:
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PTHREAD_MUTEX_RECURSIVE_NP
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Destroy mutex attribute
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Main completed</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> |
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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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