//////////////////////////////////////////////////////
// Vote.java
//  Working with Java threads and Semaphores 
//  See commented-out definition of Semaphore at bottom
//////////////////////////////////////////////////////
import java.util.*;
import java.util.concurrent.Semaphore;
import java.util.concurrent.CyclicBarrier;
import java.io.*;
import java.lang.Thread;

public class Vote implements Runnable {
   private Thread[] child;
   private final int nrThreads = 5;
   private Semaphore sem;       // semaphore ensures no more than n in voting booth
   private CyclicBarrier barrier;
   private String voteText;     // record of what has happened
   private int done;            // tells everyone when program is complete
   public void set_done() { done=1; System.out.println("Parent interrupt"); }
   private int count=0;         // count of voters in the voting booth

   public Vote()
   {
      // initialize semaphore to allow only 1 in the voting booth
      sem = new Semaphore(1);
      voteText = new String();
      barrier = new CyclicBarrier(nrThreads);

      // create 5 threads
      child = new Thread[nrThreads];
      done = 0;
      for (int i=0; i<nrThreads; i++) {
         child[i] = new Thread(this);
	 try {
	    child[i].setName("Thread"+i);
	 } catch(Exception e) { System.err.println("SetName "+e); }
         child[i].start();
      }
   }

   public void run()
   {
      Random rand = new Random();
      int total = 0;
      int vote = 0;
      int myvote = 0;
      Thread me = Thread.currentThread();
      System.out.println( "Hi From: " + me.getName());
      while (done==0) {
              // acquire semaphore to enter voting booth
	      try {
	        sem.acquire();
	      } catch(Exception e) { System.err.println("Acquire Interrupt "+e); }

	      // increment the number of voters in the booth
	      count++;
	      System.out.println("Enter vote box " + me.getName() + " Count=" + count);

	      //vote
	      try {  
		  Thread.sleep(10);
	      } catch(Exception e) { System.err.println("Sleep Interrupt "+e); }
              vote = rand.nextInt(2);
	      System.out.println("Depart voting box " + me.getName());

	      // decrement the number of voters in the booth and leave the voting booth
	      count--;

  	      sem.release();


	      // Add the vote to the total
	      total += vote;

	      // increment the number of votes this thread has performed and document the action
	      myvote++;
	      voteText = voteText + me.getName() + " ";

	      /* // synchronize all threads 
	      try {
	         barrier.await();
	      } catch(Exception e) { done=1; System.err.println("Barrier interrupted"); }
	     */ 
      }
      System.out.println( "Completed Poll Station: " + me.getName() + " with votes=" +myvote);
      if (++done == 6)
	      System.err.println(voteText);
      // thread automatically terminates when returning from run() function
   }

   public static void main(String args[]) {
      Vote mom = new Vote();
      try {
	  Thread.sleep(10000);
      } catch(Exception e) { System.err.println("Sleep Error"+e); }
      mom.set_done();
//      Thread.currentThread().getThreadGroup().interrupt();  
   }

}

/*
class Semaphore {
	private int value;

	public Semaphore() {
		value = 0;
	}

	public Semaphore(int value) {
		this.value = value;
	}

	public synchronized void Pacquire()
		throws InterruptedException {
		while (value == 0)
			wait();
		value--;
	}

	public synchronized void Vrelease() {
		++value;
		notify();
	}

}
*/