/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package multithreadeddotproduct;

import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 *
 * @author mvat
 */
public class MultiThreadedDotProduct {
    private int[] vec1 = new int[1000];
    private int[] vec2 = new int[1000];
    private Integer result = 0;

    public MultiThreadedDotProduct() {
        Random rand = new Random();

        for(int i=0;i<1000;i++) {
            vec1[i] = rand.nextInt(100);
            vec2[i] = rand.nextInt(100);
        }


        PartialDotProduct p1 = new PartialDotProduct(0,50);
        PartialDotProduct p2 = new PartialDotProduct(51,99);

        ExecutorService taskList = Executors.newFixedThreadPool(2);;
        taskList.execute(p1);
        taskList.execute(p2);

        while(p1.getStatus() == false || p2.getStatus() == false) {
            try {
                Thread.sleep(1);
            } catch (InterruptedException ex) {
                Logger.getLogger(MultiThreadedDotProduct.class.getName()).log(Level.SEVERE, null, ex);
            }
        }

        System.out.println("final result = " + result);

    }

    private void incrementResult(int n) {
        result += n;
        System.out.println("result = " + result);
    }

    private class PartialDotProduct implements Runnable {
        private int minIndex;
        private int maxIndex;
        private volatile boolean status = false;

        public PartialDotProduct(int minIndex, int maxIndex) {
            this.minIndex = minIndex;
            this.maxIndex = maxIndex;
        }

        public boolean getStatus() {
            return status;
        }

        public void run() {
            int productSum = 0;
            for(int i = minIndex; i<= maxIndex; i++) {
                productSum += (vec1[i]*vec2[i]);
                try {
                    Thread.sleep(5);
                } catch(InterruptedException ie) {}
            }

           System.out.println(productSum);
           incrementResult(productSum);
           status = true;
        }

    }
}