/******************************************************************************
* FILE: condVarBroadcast.cpp
* DESCRIPTION:
*   Example code for using Pthreads condition variables.  The main thread
*   creates threads. Each thread waits on a condition. After sleeping 3 seconds, 
*   main thread broadcasts a signal to all threads, which then complete. 
* LAST REVISED: 04/07/07 Dr. Spiegel
******************************************************************************/
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <iostream>
#ifdef __WIN32__
#include <windows.h> 
#else
#include <unistd.h>
#endif

using namespace std;

pthread_mutex_t thr_mutex;
pthread_cond_t cv;

void msleep(int milliseconds)
{
  #ifdef __WIN32__
  Sleep(milliseconds);
  #else
  usleep(static_cast<useconds_t>(milliseconds)*1000); //or use nanosleep on platforms where it's needed
  #endif
}

void *doThread(void *thrNum) 
{ cerr << "Thread " << *((int *)thrNum) << " about to lock mutex\n";
  pthread_mutex_lock(&thr_mutex);
  /*
  Lock mutex and wait for signal.  Note that the pthread_cond_wait routine
  will automatically and atomically unlock mutex while it waits. 
  */
  cerr << "Thread " << *((int *)thrNum) << " about to do condition wait\n";
  pthread_cond_wait(&cv, &thr_mutex);
  cerr << "Thread " << *((int *)thrNum) << " signaled\n";
  // when signaled, mutex is locked. Unlock it.
  pthread_mutex_unlock(&thr_mutex);
  pthread_exit(NULL);
}

int main(int argc, char *argv[])
{
  int i, rc;
  pthread_t *threads;
  if (argc!=2) {
   cerr << "Form: condVarBroadcast <# threads>\n";
   return(-1);
  }
  threads=new pthread_t[atoi(argv[1])];
  pthread_attr_t attr;

  /* Initialize mutex and condition variable objects */
  pthread_mutex_init(&thr_mutex, NULL);
  pthread_cond_init (&cv, NULL);

  /*
  For portability, explicitly create threads in a joinable state 
  */
  pthread_attr_init(&attr);
  pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
  for (i=0;i<atoi(argv[1]);i++) {
    // need separate int memory so each thread's id remains
    int *id=new int;
    *id=i;
    pthread_create(&threads[i], &attr, doThread, (void *)id);
  }
 
  msleep(3);
  pthread_cond_broadcast(&cv);

  /* Wait for all threads to complete */
  for (i = 0; i < atoi(argv[1]); i++) {
    pthread_join(threads[i], NULL);
  }
  printf ("Main(): Waited on %d  threads. Done.\n", atoi(argv[1]));

  /* Clean up and exit */
  pthread_attr_destroy(&attr);
  pthread_mutex_destroy(&thr_mutex);
  pthread_cond_destroy(&cv);
  pthread_exit (NULL);

}