ring.cs

using System.Diagnostics;
using System.Threading;

namespace ErlanCompetition
{
    internal class Program
    {
        #region private

        private static void Main()
        {
            const int n = 2000;
            const int r = 10;
            Trace.WriteLine(string.Format("Creating proc ring with {0} node(s)", n));
            Trace.WriteLine(string.Format("Passing message around {0} time(s)", r));

            var masterNode = new MasterNode();
            masterNode.Start(n, r);
            masterNode.WaitForFinish();
        }

        #endregion
    }

    public class MasterNode : Node
    {
        #region Fields

        private readonly AutoResetEvent finishResetEvent = new AutoResetEvent(false);
        private int count;
        private Node firstNode;
        private int rounds;
        private Stopwatch stopwatch;

        #endregion

        #region public

        public void Start(int n, int r)
        {
            rounds = r;
            stopwatch = Stopwatch.StartNew();

            thread = new Thread(Loop);
            thread.Start();

            firstNode = new Node(this, 1, n);
            firstNode.SendMessage(Action.PassMessage);
        }

        public void WaitForFinish()
        {
            finishResetEvent.WaitOne();
        }

        #endregion

        #region protected

        protected override void Loop()
        {
            while (run)
            {
                resetEvent.WaitOne();
                if (action == Action.Die)
                {
                    run = false;
                    Trace.WriteLine(string.Format("Took {0}.", stopwatch.Elapsed));
                    finishResetEvent.Set();
                    return;
                }
                count++;
                firstNode.SendMessage(count < rounds ? Action.PassMessage : Action.Die);
            }
        }

        #endregion
    }

    public class Node
    {
        #region Fields

        protected readonly AutoResetEvent resetEvent = new AutoResetEvent(false);
        protected Action action;
        private Node nextNode;
        protected volatile bool run = true;
        protected Thread thread;

        #endregion

        #region Constructors

        public Node()
        {
        }

        public Node(MasterNode master, int id, int total)
        {
            thread = new Thread(
                () =>
                    {
                        nextNode = id == total ? master : new Node(master, id + 1, total);
                        Loop();
                    });
            thread.Start();
        }

        #endregion

        #region public

        public void SendMessage(Action a)
        {
            action = a;
            resetEvent.Set();
        }

        #endregion

        #region protected

        protected virtual void Loop()
        {
            while (run)
            {
                resetEvent.WaitOne();
                nextNode.SendMessage(action);
                if (action == Action.Die) run = false;
            }
        }

        #endregion
    }

    public enum Action
    {
        PassMessage,
        Die,
    }
}

ring.erl

-module(ring).
-export([start/2]).

start(N, Rounds) ->
    io:format("Creating proc ring with ~p node(s)~n", [N]),
    io:format("Passing message around ~p time(s)~n", [Rounds]),
    Pid = self(),
    statistics(wall_clock),
    H = spawn(fun() -> loop(Pid, 1, N) end),
    H ! {pass, 1, Rounds},
    master(H),
    {_, Time} = statistics(wall_clock),
    io:format("Took ~p milliseconds~n",[Time]).

master(H) ->
    receive
	{pass, T, T} ->
	    H ! die;
	    %io:format("Round ~p of ~p finished~n", [T, T]);
	{pass, C, T} ->
	    %io:format("Round ~p of ~p finished~n", [C, T]),
	    H ! {pass, C+1, T},
	    master(H)
    end.    

loop(MasterPid, N, N) -> 
    bounce(MasterPid);
loop(MasterPid, I, N) ->	    			 
    NextPid = spawn(fun() -> loop(MasterPid, I+1, N) end),
    bounce(NextPid).
			    
bounce(Pid) ->
    receive
	{pass, C, Msg} ->
	    Pid ! {pass, C, Msg},
	    bounce(Pid);
	die -> 
	    Pid ! die
    end.

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