#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>
#include <unistd.h>
#include <pthread.h>

/*Async style call example in C*/

// Used for threads NOTE the starting value is zero.
static int TOTAL = 0;

// Used for async style return
static jmp_buf ENVBUF;

// The function a thread is invoked with.
void* threadJob(void *vargp)
{
    sleep(4);
    puts("Done sleeping"); // This statement doesn't get called, as the call is async.
    TOTAL += 300;
    return NULL;
}

//This function orchestrates the workers
void callWorkers(void)
{
  pthread_t worker1;
  pthread_t worker2;

  // Starts the workers,
  pthread_create(&worker1, NULL, threadJob, NULL);
  pthread_create(&worker2, NULL, threadJob, NULL);

  // jumps out of the current stack frame, hence not waiting for the threads to finish.
  longjmp(ENVBUF, 1);
}

int main(void) {

  pthread_t worker;

  if(setjmp(ENVBUF)) // This only runs after longjmp is called.
  {

    printf("async calls commenced, total is still %d\n", TOTAL);
    exit(0);
  }
  else
  {
    printf("Calling worker threads, total is now %d\n", TOTAL);
    callWorkers();
  }
  return 0;
}