/*
 *  This example base on code from: 
 *  B. Nichols, D. Buttlar, and J. Proulx Farrell,  "Pthreads Programming,"
 *  O'reilly, 1996.
 *  
 */

#include <stdio.h> 
#include <pthread.h> 
#define TCOUNT 10
#define WATCH_COUNT 12


void watch_count(int *);
void inc_count(int *);

int count = 0;
pthread_mutex_t count_mutex=PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t count_threshold_cv = PTHREAD_COND_INITIALIZER;
int thread_ids[3] = {0,1,2};

int main (int argc, char **argv) {

  int i;
  pthread_t threads[3];
  pthread_attr_t custom_sched_attr;

  /* set scheduling policy to system so braindead solaris doesn't
     run threads sequentially */
  pthread_attr_init(&custom_sched_attr);
  pthread_attr_setscope(&custom_sched_attr,PTHREAD_SCOPE_SYSTEM);



  /* start threads */
  pthread_create(&threads[0], &custom_sched_attr, (void *) inc_count, (void *) &thread_ids[0]);
  pthread_create(&threads[1], &custom_sched_attr, (void *) inc_count, (void *) &thread_ids[1]);
  pthread_create(&threads[2], &custom_sched_attr, (void *) watch_count, (void *) &thread_ids[2]);

  /* wait for threads to complete */
  for (i = 0; i < 3; i++) {
    pthread_join(threads[i],NULL);
  }

  return 0;
}


void watch_count(int *idp) 
{
  pthread_mutex_lock(&count_mutex);
  printf("watch_count(): Starting thread %d, count is %d\n",*idp, count);

  while(count < WATCH_COUNT) {
    pthread_cond_wait(&count_threshold_cv, &count_mutex);
    printf("watch_count(): Thread %d, count is %d\n",*idp, count);
  }
  pthread_mutex_unlock(&count_mutex);
}


void inc_count(int *idp) 
{
  int i,j,x;

  x = 1;

  for (i = 0; i < TCOUNT; i++) {
    pthread_mutex_lock(&count_mutex);
    count++;
    printf("inc_count(): Thread %d, old count %d, new count %d\n",*idp, count -1, count);
    if (count == WATCH_COUNT)
      pthread_cond_signal(&count_threshold_cv);
    pthread_mutex_unlock(&count_mutex);

    /* do some work to allow another thread to run */
    for (j = 0; j < 10000000; j++) 
      x = x + i;

  }
}