package Paradigms.List11.CommonStaticVariableResolvings;



public class IntCellMonitor {

    // function sets isSet on false and on the beggining checks

    // if isSet is false then stops the execution of the thread until another thread invokes the notify

    // then condition is checked one more time

    // it prevents from read the same value by two threads until first thread will call set function

    // the same history with set

    public synchronized int getN(){

        while(!isSet){

            waitForNotifying();

        }

        isSet=false;

        notifyAll();

        // Wakes up all threads that are waiting on this object's monitor

        return n;

    }



    // function sets isSet on true and on the beggining checks

    // if isSet is true then stops the execution of the thread until another thread invokes the notify

    // then condition is checked one more time

    // it prevents from set the same value by two threads until first thread will call get function

    // the same history with set

    public synchronized void setN(int n){

        while(isSet){

            waitForNotifying();

        }

        this.n = n;

        isSet = true;

        notifyAll();

    }



    // above approach protects from the replicated call of getN or setN between threads

    // it forces to call getN before setN everytime

    private void waitForNotifying(){

        try{

            wait();

            // causes the current thread to wait until

            // another thread invokes the notify/notifyAll() method for this obj

        }catch(InterruptedException e){

            e.printStackTrace();

        }

    }



    private boolean isSet = true;

    private int n = 0;

}



class CountMonitor extends Thread{

    static IntCellMonitor n = new IntCellMonitor();



    @Override

    public void run(){

        for (int i = 0; i < 200000; i++){

            int temp = n.getN();

            n.setN(temp+1);

        }

    }



    public static void main(String[] args){

        CountMonitor thread1 = new CountMonitor();

        CountMonitor thread2 = new CountMonitor();

        thread1.start();

        thread2.start();

        try{

            thread1.join();

            thread2.join();

        }catch(InterruptedException e){

            System.out.println(e.getStackTrace());

            System.out.println("Catched exception");

        }

        System.out.println("The value of n is " + n.getN());

        System.out.println("Monitor edition");

    }

}