Demonstrates decorrelated jitter with Polly (issue 245)

DecorrelatedJitter.cs

using System;
using System.Collections.Generic;
using Polly;

namespace DecorrelatedJitter
{
    class Program
    {
        static void Main(string[] args)
        {
            TimeSpan maxDelay = TimeSpan.FromSeconds(2);
            TimeSpan seedDelay = TimeSpan.FromMilliseconds(100);
            int maxRetries = 20;

            Policy retryWithDecorrelatedJitter = Policy
                .Handle<DivideByZeroException>() 
                .WaitAndRetry(DecorrelatedJitter(maxRetries, seedDelay, maxDelay), onRetry: (e, t) => Console.WriteLine($"Retry delay: {t.TotalMilliseconds} ms."));

            try
            {
                retryWithDecorrelatedJitter.Execute(() => { throw new DivideByZeroException(); });
            }
            catch
            {
                // intentionally empty to swallow final exception.  This is only a console app to display retry delays generated by a jitter strategy with Polly.
            }

            Console.WriteLine("Done");
            Console.ReadKey();
        }

        public static IEnumerable<TimeSpan> DecorrelatedJitter(int maxRetries, TimeSpan seedDelay, TimeSpan maxDelay)
        {
            Random jitterer = new Random();
            int retries = 0;

            double seed = seedDelay.TotalMilliseconds;
            double max = maxDelay.TotalMilliseconds;
            double current = seed;

            while (++retries <= maxRetries)
            {
                current = Math.Min(max, Math.Max(seed, current * 3 * jitterer.NextDouble())); // adopting the 'Decorrelated Jitter' formula from https://www.awsarchitectureblog.com/2015/03/backoff.html.  Can be between seedMs and previousMs * 3.  Mustn't exceed maxDelay.
                yield return TimeSpan.FromMilliseconds(current);
            }
        }
    }
}