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



int data_avail = 0;
int data_item = 0;
pthread_mutex_t data_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t data_cond = PTHREAD_COND_INITIALIZER;

void *producer(void *arg) 
{

  int myrank = * (int *)arg;
  while (1) {
    pthread_mutex_lock(&data_mutex);
    //	Produce data
    //	Insert data into queue;
    data_avail =1;
    data_item ++;	
    printf("Rank %d produced one item, total %d item(s).\n", myrank, 
	   data_item);
    pthread_cond_signal(&data_cond);

    pthread_mutex_unlock(&data_mutex);
    sleep (1);
  }
}

void *consumer(void *arg) 
{
  int myrank = * (int *)arg;
 
  while (1) {
    pthread_mutex_lock(&data_mutex);

    while( !data_avail ) {
      pthread_cond_wait(&data_cond, &data_mutex);
    }
    // Extract data from queue;
    data_item --;
    if (data_item == 0) data_avail = 0;
    
    printf("Rank %d consumed one item, total %d items\n", myrank, 
	   data_item);
    pthread_mutex_unlock(&data_mutex);
    sleep (1);  // consume_data();
  }
}

int tmp[5];
int main(int argc, char* argv[]){

     pthread_t thread[5];
     int i, j;

     for (j=0; j<2; j++) {
       tmp[j] = j;
       if ((i=pthread_create(&thread[j], NULL, producer, 
			     (void*)&tmp[j])) != 0) {
	 printf("thread creation failed. %d\n", j);
       }
     }

     for (j=0; j<2; j++) {
       tmp[j] = j;
       if ((i=pthread_create(&thread[j+2], NULL, consumer, 
			     (void*)&tmp[j])) != 0) {
	 printf("aathread creation failed. %d\n", j);
       }
     }


     pthread_join(thread[0], NULL);
     pthread_join(thread[1], NULL);
     pthread_join(thread[2], NULL);
     pthread_join(thread[3], NULL);

     printf("Exiting main\n");
     return 0;
}