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

using namespace std;

// prototype for thread routine
void *print_message_function1 ( void *ptr );
void *print_message_function2 ( void *ptr );

// struct to hold data to be passed to a thread: now it has a mutex pointer
typedef struct str_thdata
{
  int thread_no;
  int shared_buf[1000];
  int buf_size;
  pthread_mutex_t *mutex;
} thdata;

int main()
{
  pthread_t thread1, thread2;
  thdata data;

  // mutex
  pthread_mutex_t mutex;
  pthread_mutex_init(&mutex, NULL);

  // initialize data to pass to thread 1
  data.thread_no = 1;
  data.buf_size = 0;
  data.mutex = &mutex;

  // create threads 1 and 2
  pthread_create (&thread1, NULL, print_message_function1, (void *) &data);
  pthread_create (&thread2, NULL, print_message_function2, (void *) &data);

  pthread_join(thread1, NULL);
  pthread_join(thread2, NULL);

  exit(0);
}

void *print_message_function1 ( void *ptr )
{
  thdata *data;
  data = (thdata *) ptr;  // type cast to a pointer to thdata
  pthread_mutex_t *mutex = data->mutex;

  int i;
  int cnt = 0;
  while (cnt < 999) {
    for (i=cnt;i<cnt+50;i++) {
      pthread_mutex_lock (mutex);
      printf("Thread %d says %s %d \n", data->thread_no, "Hello", i);
      data->shared_buf[i]=i;
      data->buf_size += 1;
      pthread_mutex_unlock (mutex);
    }
    cnt += 50;
  }

  pthread_exit(0);
}

void *print_message_function2 ( void *ptr )
{
  thdata *data;
  data = (thdata *) ptr;  // type cast to a pointer to thdata
  int cnt = 0;
  int k;
  pthread_mutex_t *mutex = data->mutex;

  while (cnt < 999) {
    if (data->buf_size >= 100) {
      pthread_mutex_lock (mutex);
      printf ("buf_size: %d \n", data->buf_size);
      for (k=cnt;k<cnt+100;k++) {
        printf("Thread %d says %s %d %d \n", data->thread_no, "Hi", k, data->shared_buf[k]);
      }
      data->buf_size -= 100;
      cnt += 100;
      pthread_mutex_unlock (mutex);
    }
  }

  pthread_exit(0);
}