Example: Cancel a thread in a Pthread program

/*
Filename: ATEST13.QCSRC
The output of this example is as follows:
 Enter Testcase - LIBRARY/ATEST13
 Create/start a thread
 Wait a bit until we 'realize' the thread needs to be canceled
 Thread: Entered
 Thread: Looping or long running request
 Thread: Looping or long running request
 Thread: Looping or long running request
 Wait for the thread to complete, and release its resources
 Thread: Looping or long running request
 Thread status indicates it was canceled
 Main completed
*/
#define _MULTI_THREADED
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define checkResults(string, val) {               \
 if (val) {                                                    \
   printf("Failed with %d at %s", val, string); \
   exit(1);                                                    \
 }                                                               \
}
 
void *theThread(void *parm)
{
   printf("Thread: Entered\n");
   while (1) {
      printf("Thread: Looping or long running request\n");
      pthread_testcancel();
      sleep(1);
   }
   return NULL;
}
 
int main(int argc, char **argv)
{
  pthread_t             thread;
  int                   rc=0;
  void                 *status;
 
  printf("Enter Testcase - %s\n", argv[0]);
 
  printf("Create/start a thread\n");
  rc = pthread_create(&thread, NULL, theThread, NULL);
  checkResults("pthread_create()\n", rc);
 
  printf("Wait a bit until we 'realize' the thread needs to be canceled\n");
  sleep(3);
  rc = pthread_cancel(thread);
  checkResults("pthread_cancel()\n", rc);
 
  printf("Wait for the thread to complete, and release its resources\n");
  rc = pthread_join(thread, &status);
  checkResults("pthread_join()\n", rc);
 
  printf("Thread status indicates it was canceled\n");
  if (status != PTHREAD_CANCELED) {
     printf("Unexpected thread status\n");
  }
 
  printf("Main completed\n");
  return 0;
}