Grim Reaper Helps Destroy Objects

GrimReaper.cs

using System;
using System.Threading;
using System.Collections.Generic;
using System.Linq;
using Assets.Game.Scripts.Network;

namespace Assets.Game.Scripts
{
	public class GrimReaper
	{
		private static GrimReaper _instance;

		#region SingletonConstructor
		public static GrimReaper Instance
		{
			get
			{
				return _instance ?? (_instance = new GrimReaper());
			}
		}
		#endregion

		private List<BuildableMapObject> _deathRow;
		private List<BuildableMapObject> _executionLine;
		private DateTime _executionTime;
		private TimeSpan _executionGracePeriod;
		private Mutex _deathRowLock;
		private Mutex _summonLock;
		private bool _isSummoned;

		public GrimReaper()
		{
			_deathRowLock = new Mutex();
			_summonLock = new Mutex();
			_isSummoned = false;
			_executionGracePeriod = new TimeSpan(0, 0, GracePeriodSeconds);
			_deathRow = new List<BuildableMapObject>();
			_executionLine = new List<BuildableMapObject>();
		}

		public void QueueDeath(BuildableMapObject o, DateTime timeOfDeath)
		{
			// Make sure we get the lock. We need to give the object its
			//   grace period fairly
			_deathRowLock.WaitOne();
			_deathRow.Add(o);
			_executionTime = timeOfDeath + _executionGracePeriod;
			_deathRowLock.ReleaseMutex();
		}

		public bool IsSummoned()
		{
			return _isSummoned;
		}

		public void Summon()
		{
			if(IsSummoned())
			{
				return;
			}

			// the grim reaper has got a job like everybody else!
			//   give him a break; he can't be in more than one
			//   place at at time
			_isSummoned = true;
			_summonLock.WaitOne();
			
			ThreadPool.QueueUserWorkItem(AnswerSummon);
		}

		private void AnswerSummon(Object stateInfo)
		{
			if(_deathRow.Count > 0)
			{
				while(Helpers.ServerUtcNow < _executionTime)
				{
					TakeBreakUntil(_executionTime);
				}

				// Only those that have been fairly given a grace period can be killed
				_deathRowLock.WaitOne();
				_executionLine = new List<BuildableMapObject>(_deathRow);
				_deathRow.Clear();
				_deathRowLock.ReleaseMutex();

				Execute(_executionLine);
			}

			_summonLock.ReleaseMutex();
			_isSummoned = false;
		}

		private void TakeBreakUntil(DateTime clockInTime)
		{
			Thread.Sleep(Convert.ToInt32((clockInTime - Helpers.ServerUtcNow).TotalMilliseconds));
		}

		public void Execute(List<BuildableMapObject> executionLine)
		{
			var message = executionLine.Select(t => t.Id).ToArray();
			// execute post-killing code
		}
	}
}