Example: Space location locks in Pthread programs
This example shows a Pthread program that dynamically initializes an integer using a space location lock for synchronization.
Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.
/*
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;
}