/* Program for the classic dining philosopher problem in operating system */
package javacodes;

public class Dine {


    public static void main(String[] args) {

        int x = 10;

        Log.msg(String.valueOf(x));
        /* Initializing 5 chopsticks */
        Chopstick[] chopistics = new Chopstick[5];

        for (int i = 0; i < chopistics.length; i++) {

            chopistics[i] = new Chopstick("C: " + i);
        }

        // Initialising five philosophers and their corresponding positions 
        Philosopher[] philosophers = new Philosopher[5];

        philosophers[0] = new Philosopher("P: 0 - ", chopistics[0], chopistics[1]);

        philosophers[1] = new Philosopher("P: 1 - ", chopistics[1], chopistics[2]);

        philosophers[2] = new Philosopher("P: 2 - ", chopistics[2], chopistics[3]);

        philosophers[3] = new Philosopher("P: 3 - ", chopistics[3], chopistics[4]);

        philosophers[4] = new Philosopher("P: 4 - ", chopistics[4], chopistics[0]);

        for (int i = 0; i < philosophers.length; i++) {

            Log.msg("Thred " + i);

            Thread t = new Thread(philosophers[i]);

            t.start();
        }
    }
}

//Class for philosophers
class Philosopher extends Thread {

    private Chopstick leftChopistick;

    private Chopstick rightChopistick;

    private String name;

    private int state;

    public Philosopher(String name, Chopstick left, Chopstick right) {

        this.state = 1;

        this.name = name;

        leftChopistick = left;

        rightChopistick = right;
    }

    public void eat() {
        // While eating, every philosopher pics up the left chopstick first and the the right chopstick. If the philosopher gets both the chopsticks
        // he eats for 1000 ms and then releases the chopsticks
        //Else he waits for chopsticks to be free
        if (!leftChopistick.used) {

            if (!rightChopistick.used) {

                leftChopistick.take();

                rightChopistick.take();

                Log.msg(name + " : Eat");

                Log.Delay(1000);

                leftChopistick.release();

                rightChopistick.release();
            }
        }
        think();
    }

    public void think() {

        this.state = 1;

        Log.msg(name + " : Think");

        Log.Delay(1000);

    }

    public void run() {

        for (int i = 0; i <= 10; i++) {

            eat();
        }
    }
}

class Log {

    public static void msg(String msg) {

        System.out.println(msg);
    }

    public static void Delay(int ms) {
        try {
            Thread.sleep(ms);
        } catch (InterruptedException ex) {
        }
    }
}

//Class for chopstick that provides use and release functionalities to pilosophers
class Chopstick {

    public boolean used;

    public String name;

    public Chopstick(String name) {

        this.name = name;
    }
    //method to reserve the chopstick for use

    public synchronized void take() {

        Log.msg("Used :: " + name);

        this.used = true;
    }

    //method to release the chopstick for use
    public synchronized void release() {

        Log.msg("Released :: " + name);

        this.used = false;
    }
}