#include <pthread.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include "prtastr.h"
#define BUFFSIZE 1024
static pthread_mutex_t join_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  join_cond  = PTHREAD_COND_INITIALIZER;
static int delay = 0;
static int nthreads = 0;
void *join_thread_main(void *arg){
  char buff[BUFFSIZE];
  sprintf(buff,"I'm the spawned thread chug chug chugging along\n");
  prtastr(buff, STDERR_FILENO, delay);
  pthread_mutex_lock(&join_mutex);
  fprintf(stderr, "thread signalling finished\n");
  pthread_cond_signal(&join_cond);
  pthread_mutex_unlock(&join_mutex);
  pthread_exit(NULL);
}
int main(int argc,  char *argv[]){
  if((argc != 3) ||
     ((nthreads = atoi(argv[1]))  < 0) ||
     ((delay = atoi(argv[2]))  < 0)) {
    fprintf (stderr, "Usage: %s nthreads delay\n", argv[0]);
    exit(EXIT_FAILURE); }
  {
    int i;
    int threads_finished = 0;
    pthread_t join_threads[nthreads];
    fprintf(stderr, "main thread spawning %d threads\n", nthreads);
    pthread_mutex_lock(&join_mutex);
    for(i = 0; i < nthreads; i++)
      if(pthread_create(&join_threads[i],
                        NULL,
                        join_thread_main,
                        NULL) != 0){
        perror("thread creation failed");
        exit(EXIT_FAILURE); }
    fprintf(stderr, "main thread waiting after spawning %d threads\n", i);
    while(threads_finished < nthreads){
      pthread_cond_wait(&join_cond, &join_mutex);
      threads_finished++;
      fprintf(stderr, "threads finished = %d\n", threads_finished);
    }
    fprintf(stderr, "main thread awoken\n");
    exit(EXIT_SUCCESS);
  }
}