using System;

public class Program

{

    public static void Main()

    {

        var rr = new RoundRobinCounter(4);

        for (int i = 0; i< 1000; i++)

        {

            var next = rr.GetNext();

            Console.WriteLine("{0} === {1}", i, next);

        }

    }

}

​

public class RoundRobinCounter

{

    private int _max;

    private int _currentNumber = Int32.MaxValue - 100;

    public RoundRobinCounter(int max)

    {

        _max = max;

    }

    public int GetNext()

    {

        uint nextNumber = unchecked((uint)System.Threading.Interlocked.Increment(ref _currentNumber));

        int result = (int) (nextNumber % _max);

        return result;

    }

}