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

void *fproducer(void *);
void *fconsumer(void *);

typedef struct {
  pthread_mutex_t working;
  int hasData;
  int buffer;
} UserData;

int main(int argc, char *argv[]) {
  pthread_t producer, consumer;
  int rp, rc;
  UserData ud;

  pthread_mutex_init( &(ud.working), NULL );
  ud.hasData = 0;
  ud.buffer = 0;

  // spawn the producer thread
  rp = pthread_create( &producer, NULL, fproducer, &ud );

  // spawn the consumer thread
  rc = pthread_create( &consumer, NULL, fconsumer, &ud);

  // wait until both are done (join)
  pthread_join( producer, NULL );
  pthread_join( consumer, NULL );

  pthread_mutex_destroy( &(ud.working) );

  // terminate
  printf("Terminating\n");

  return(0);
}

void *fproducer( void *userdata ) {
  int i;
  UserData *ud = (UserData *)userdata;

  
  for(i=0;i<10;) {
    if( !ud->hasData) {
      printf("producer locking thread\n");
      pthread_mutex_lock( &(ud->working) );

      printf("Producer placing %d\n", i+1);
      ud->buffer = i+1;
      ud->hasData = 1;
      i++;

      printf("producer unlocking thread\n");
      pthread_mutex_unlock( &(ud->working) );
    }
  }

  return( NULL );
}

void *fconsumer( void *userdata ) {
  int i;
  UserData *ud = (UserData *)userdata;

  for(i=0;i<10;) {
    if(ud->hasData) {
      printf("consumer locking thread\n");
      pthread_mutex_lock( &(ud->working) );

      printf("Consumer received data %d\n", ud->buffer);
      ud->hasData = 0;
      i++;

      printf("consumer unlocking thread\n");
      pthread_mutex_unlock( &(ud->working) );
    }
  }

  return( NULL );
}