190 lines
6.0 KiB
HTML
190 lines
6.0 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_setpshared()--Set Process Shared Attribute in Mutex Attributes Object</title>
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<a name="Top_Of_Page"></a>
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<h2>pthread_mutexattr_setpshared()--Set Process Shared Attribute in Mutex Attributes Object</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_setpshared(pthread_mutexattr_t *attr,
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int pshared);</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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<br>
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Threadsafe: Yes<br>
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<br>
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Signal Safe: Yes<br>
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<br>
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</div>
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<p>The <strong>pthread_mutexattr_setpshared</strong>() function sets the current pshared attribute for the mutex attributes object. The process shared attribute indicates whether the mutex that is created using the mutex attributes object can be shared between threads in separate processes (<strong>PTHREAD_PROCESS_SHARED</strong>) or shared between threads within the same process (<strong>PTHREAD_PROCESS_PRIVATE</strong>).</p>
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<p>Even if the mutex in storage is accessible from two separate processes, it cannot be used from both processes unless the process shared attribute is <strong>PTHREAD_PROCESS_SHARED</strong>.</p>
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<p>The default pshared attribute for mutex attributes objects is <strong>PTHREAD_PROCESS_PRIVATE</strong>.</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 variable containing the mutex attributes object <a name="297035"></a></dd>
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<dt><strong>pshared</strong></dt>
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<dd>(Input) One of <strong>PTHREAD_PROCESS_SHARED</strong> or <strong>PTHREAD_PROCESS_PRIVATE</strong></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_setpshared</strong>() was successful.</dd>
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<dt><strong>value</strong></dt>
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<dd><strong>pthread_mutexattr_setpshared</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_setpshared</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_52.htm">pthread_mutexattr_getpshared()</a>--Get Process Shared Attribute from Mutex Attributes Object<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 showPshared(pthread_mutexattr_t *mta) {
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int rc;
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int pshared;
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printf("Check pshared attribute\n");
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rc = pthread_mutexattr_getpshared(mta, &pshared);
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checkResults("pthread_mutexattr_getpshared()\n", rc);
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printf("The pshared attributed is: ");
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switch (pshared) {
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case PTHREAD_PROCESS_PRIVATE:
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printf("PTHREAD_PROCESS_PRIVATE\n");
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break;
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case PTHREAD_PROCESS_SHARED:
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printf("PTHREAD_PROCESS_SHARED\n");
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break;
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default :
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printf("! pshared Error !\n");
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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("Entering testcase\n");
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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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showPshared(&mta);
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printf("Change pshared attribute\n");
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rc = pthread_mutexattr_setpshared(&mta, PTHREAD_PROCESS_SHARED);
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checkResults("pthread_mutexattr_setpshared()\n", rc);
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showPshared(&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>Entering testcase
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Create a default mutex attribute
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Check pshared attribute
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The pshared attribute is: PTHREAD_PROCESS_PRIVATE
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Change pshared attribute
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The pshared attribute is: PTHREAD_PROCESS_SHARED
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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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<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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