quasarwhispers.java

package foo;

import co.paralleluniverse.fibers.Fiber;
import co.paralleluniverse.fibers.SuspendExecution;
import co.paralleluniverse.strands.SuspendableRunnable;
import co.paralleluniverse.strands.channels.Channel;
import co.paralleluniverse.strands.channels.Channels;
import co.paralleluniverse.strands.channels.LongChannel;

public class quasarwhispers {

    static void quasarWhispers(int n) {
        class Whisperer implements SuspendableRunnable {
            private LongChannel left, right;

            public Whisperer(LongChannel left, LongChannel right) {
                this.left = left;
                this.right = right;
            }
            @Override
            public void run() throws SuspendExecution, InterruptedException {
                try {
                    long val = left.receive();
                    right.send(val + 1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
        final LongChannel leftmost = Channels.newLongChannel(0);

        LongChannel left = leftmost;
        LongChannel right = leftmost;
        for (long i = 0; i < n; i++) {
            right = Channels.newLongChannel(0);
            new Fiber<Void>(new Whisperer(left, right)).start();
            left = right;
        }

        new Fiber<Void>(() -> {
            try {
                leftmost.send(1L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();

        try {
            System.out.println(right.receive());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (SuspendExecution suspendExecution) {
            suspendExecution.printStackTrace();
        }
    }

    static void exec() {
        for (int i = 0; i < 20; i++)
            quasarWhispers(1000000);
    }
}