137 lines
6.4 KiB
HTML
137 lines
6.4 KiB
HTML
|
<?xml version="1.0" encoding="UTF-8"?>
|
||
|
|
<!DOCTYPE html
|
||
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
|
|
<html lang="en-us" xml:lang="en-us">
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||
|
|
<meta name="security" content="public" />
|
||
|
|
<meta name="Robots" content="index,follow" />
|
||
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
||
|
|
<meta name="DC.Type" content="reference" />
|
||
|
|
<meta name="DC.Title" content="Example: Space location locks in Pthread programs" />
|
||
|
|
<meta name="abstract" content="This example shows a Pthread program that is dynamically initializing an integer using the space location lock synchronization primitive." />
|
||
|
|
<meta name="description" content="This example shows a Pthread program that is dynamically initializing an integer using the space location lock synchronization primitive." />
|
||
|
|
<meta name="DC.Relation" scheme="URI" content="rzahwsllco.htm" />
|
||
|
|
<meta name="DC.Relation" scheme="URI" content="rzahwoneco.htm" />
|
||
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
|
||
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
|
||
|
|
<meta name="DC.Format" content="XHTML" />
|
||
|
|
<meta name="DC.Identifier" content="rzahwe16-e16rx" />
|
||
|
|
<meta name="DC.Language" content="en-us" />
|
||
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
||
|
|
<!-- US Government Users Restricted Rights -->
|
||
|
|
<!-- Use, duplication or disclosure restricted by -->
|
||
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
||
|
|
<title>Example: Space location locks in Pthread programs</title>
|
||
|
|
</head>
|
||
|
|
<body id="rzahwe16-e16rx"><a name="rzahwe16-e16rx"><!-- --></a>
|
||
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
||
|
|
<h1 class="topictitle1">Example: Space location locks in Pthread programs</h1>
|
||
|
|
<div><p>This example shows a Pthread program that is dynamically initializing
|
||
|
|
an integer using the space location lock synchronization primitive.</p>
|
||
|
|
<div class="section"><div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms
|
||
|
|
of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
|
||
|
|
</div>
|
||
|
|
<div class="example"> <pre>/*
|
||
|
|
Filename: ATEST19.QCSRC
|
||
|
|
The output of this example is as follows:
|
||
|
|
Enter Testcase - LIBRARY/ATEST19
|
||
|
|
Hold Lock to prevent access to shared data
|
||
|
|
Create/start threads
|
||
|
|
Thread 00000000 00000025: Entered
|
||
|
|
Wait a bit until we are 'done' with the shared data
|
||
|
|
Thread 00000000 00000026: Entered
|
||
|
|
Thread 00000000 00000027: Entered
|
||
|
|
Unlock shared data
|
||
|
|
Wait for the threads to complete, and release their resources
|
||
|
|
Thread 00000000 00000025: Start critical section, holding lock
|
||
|
|
Thread 00000000 00000025: End critical section, release lock
|
||
|
|
Thread 00000000 00000026: Start critical section, holding lock
|
||
|
|
Thread 00000000 00000026: End critical section, release lock
|
||
|
|
Thread 00000000 00000027: Start critical section, holding lock
|
||
|
|
Thread 00000000 00000027: End critical section, release lock
|
||
|
|
Main completed
|
||
|
|
*/
|
||
|
|
#define _MULTI_THREADED
|
||
|
|
#include <pthread.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
#include <mih/milckcom.h> /* Lock types */
|
||
|
|
#include <mih/locksl.h> /* LOCKSL instruction */
|
||
|
|
#include <mih/unlocksl.h> /* UNLOCKSL instruction */
|
||
|
|
|
||
|
|
#define checkResults(string, val) { \
|
||
|
|
if (val) { \
|
||
|
|
printf("Failed with %d at %s", val, string); \
|
||
|
|
exit(1); \
|
||
|
|
} \
|
||
|
|
}
|
||
|
|
|
||
|
|
#define NUMTHREADS 3
|
||
|
|
int sharedData=0;
|
||
|
|
int sharedData2=0;
|
||
|
|
|
||
|
|
void *theThread(void *parm)
|
||
|
|
{
|
||
|
|
int rc;
|
||
|
|
printf("Thread %.8x %.8x: Entered\n", pthread_getthreadid_np());
|
||
|
|
locksl(&sharedData, _LENR_LOCK); /* Lock Exclusive, No Read */
|
||
|
|
/********** Critical Section *******************/
|
||
|
|
printf("Thread %.8x %.8x: Start critical section, holding lock\n",
|
||
|
|
pthread_getthreadid_np());
|
||
|
|
/* Access to shared data goes here */
|
||
|
|
++sharedData; --sharedData2;
|
||
|
|
printf("Thread %.8x %.8x: End critical section, release lock\n",
|
||
|
|
pthread_getthreadid_np());
|
||
|
|
unlocksl(&sharedData, _LENR_LOCK); /* Unlock Exclusive, No Read */
|
||
|
|
/********** Critical Section *******************/
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
int main(int argc, char **argv)
|
||
|
|
{
|
||
|
|
pthread_t thread[NUMTHREADS];
|
||
|
|
int rc=0;
|
||
|
|
int i;
|
||
|
|
|
||
|
|
printf("Enter Testcase - %s\n", argv[0]);
|
||
|
|
|
||
|
|
printf("Hold Lock to prevent access to shared data\n");
|
||
|
|
locksl(&sharedData, _LENR_LOCK); /* Lock Exclusive, No Read */
|
||
|
|
|
||
|
|
printf("Create/start threads\n");
|
||
|
|
for (i=0; i <NUMTHREADS; ++i) {
|
||
|
|
rc = pthread_create(&thread[i], NULL, theThread, NULL);
|
||
|
|
checkResults("pthread_create()\n", rc);
|
||
|
|
}
|
||
|
|
|
||
|
|
printf("Wait a bit until we are 'done' with the shared data\n");
|
||
|
|
sleep(3);
|
||
|
|
printf("Unlock shared data\n");
|
||
|
|
unlocksl(&sharedData, _LENR_LOCK); /* Unlock Exclusive, No Read */
|
||
|
|
|
||
|
|
printf("Wait for the threads to complete, and release their resources\n");
|
||
|
|
for (i=0; i <NUMTHREADS; ++i) {
|
||
|
|
rc = pthread_join(thread[i], NULL);
|
||
|
|
checkResults("pthread_join()\n", rc);
|
||
|
|
}
|
||
|
|
|
||
|
|
printf("Main completed\n");
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
</pre>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div>
|
||
|
|
<div class="familylinks">
|
||
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahwsllco.htm" title="A space location lock puts a logical lock on any single byte of storage. The lock does not change the storage or effect your application's access to the storage. The lock is a piece of information recorded by the system.">Space location locks</a></div>
|
||
|
|
</div>
|
||
|
|
<div class="relconcepts"><strong>Related concepts</strong><br />
|
||
|
|
<div><a href="rzahwoneco.htm" title="At times, you might want to defer the initialization of resources until a thread requires them. However, your application might require that multiple threads use a certain resource, which requires you to initialize the resource only once in a threadsafe way.">One-time initialization and thread safety</a></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|