/**
* A very simple program, just add to a single counter on 
* several threads all running at the same time. The point is
* that the standard long will loose some counts along the way
* because the threads will interact.  
* 
* @author gtowell
* Created Aug 2022
* Modified: Nov 2022 gtowell
*/
public class BCounter {
    // this is the shared memory !!!
    public long countt = 0;
    
    /**
     * a private class to implement the stuff that will ge run
     * in a separate thread.
     */
    private class TCounter extends Thread {
        private long reps;
        /**
         * Set up the class
         * @param reps the amount of work to do
         */
        public TCounter(long reps) {
            this.reps = reps;
        }

        public void run() {
            for (long j = 0; j < reps; j++)
                countt++;
        }
    }

    /**
    * Test with unprotected long as shared memory
    * @param reps
    * @param threadsToStart
    */
    public void testt(long reps, long threadsToStart) {
        // hold each thread object so it can be asked if it is running
        TCounter[] obs = new TCounter[(int) threadsToStart];
        // start the threads
        for (int i = 0; i < threadsToStart; i++) {
            obs[i] = new TCounter(reps);
            obs[i].start();
        }

        boolean live = true; // true is threads are running
        int chk = 0; // count the number of times you have checked
        // check if thread are running in a busy loop.
        while (live) {
            try {
                Thread.sleep(50);
            } catch (Exception e) {
            }
            live = false;
            for (TCounter tc : obs) {
                live = live || tc.isAlive();
            }
            System.out.println(live + " " + chk++);
        }
        
    }
    
    
    public static void main(String[] args) {
        BCounter cc = new BCounter();
        long r = 100000000;  // word in each thread
        long t = 100; // number of threads
        cc.testt( r, t);
        System.out.format("Long     %d\n", cc.countt);
        System.out.format("Expected %d\n", r*t);
    }
}