Event traffic calming

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;

using NLipsum.Core;

namespace SampleDomain
{
	public class OrderRepository : IOrderRepository
	{
		private const int Capacity = 100;
		private const int RemoveWhenFull = 50;

		private readonly Random _randomPause = new Random();
		private readonly List<Order> _orders = new List<Order>();
		private readonly LipsumGenerator _lipsum = new LipsumGenerator(Lipsums.LoremIpsum, false);

		private bool _generating;

		public void StartGenerating()
		{
			_generating = true;

			Action generateAsynchronously = () => GenerateOrders();
			generateAsynchronously.BeginInvoke(null, null);
		}

		private void GenerateOrders()
		{
			while (_generating) {
				var order = GenerateOrder();
				PutOrderIn(order);

				OnOrderArrived(EventArgs.Empty);
				SleepRandomTime();
			}
		}

		private Order GenerateOrder()
		{
			return new Order {
				CreatedAt = DateTime.Now,
				Title = _lipsum.GenerateSentences(1)[0]
			};
		}

		private void PutOrderIn(Order order)
		{
			if (_orders.Count == Capacity)
				RemoveFromFront();

			_orders.Add(order);
		}

		private void RemoveFromFront()
		{
			_orders.RemoveRange(0, RemoveWhenFull);
		}

		private void SleepRandomTime()
		{
			var time = _randomPause.Next(0, 10);
			Thread.Sleep(time);
		}

		public void StopGenerating()
		{
			_generating = false;
		}

		public IEnumerable<Order> ListFrom(DateTime startDate)
		{
			return _orders.Where(x => x.CreatedAt >= startDate);
		}

		public event EventHandler OrderArrived;

		private void OnOrderArrived(EventArgs e)
		{
			if (OrderArrived != null)
				OrderArrived(this, e);
		}
	}
}