gistfile1.cs

public static class IPFilter
{
	public static int MaxRequestsPerGarbageCollect = 60;
	public static int GarbageCollectFrequencyInMinutes = 60;
	public static Action<Entry> RequestExceededAction = (e) => { }
	
	private static IDictionary<string, Entry> entries = new Dictionary<string, Entry>();
	private static DateTime lastGarbageCollect;
		
	public static void Log(string ip)
	{
		var entry = GetOrCreateEntry(ip);
		entry.Requests++;
		entry.LastRequest = DateTime.Now;
		
		CheckEntry(entry);
		GarbageCollect();
	}
	
	private static Entry GetOrCreateEntry(string ip)
	{
		Entry entry = null;
		entries.TryGet(ip, out entry);
		if (entry == null)
			entry = new Entry() { Ip = ip };
			
		return entry;
	}
	
	private static void CheckEntry(Entry entry)
	{
		if (entry.Requests > MaxRequestsPerGarbageCollect)
		{
			RequestExceededAction(entry);
			entries.Remove(entry.Ip);
		}
	}
	
	private static void GarbageCollect()
	{
		if (DateTime.Now <= lastGarbageCollect.AddMinutes(GarbageCollectFrequencyInMinutes))
		{
			return;
		}
		
		var oldEntries = entries.Where(kv=>kv.Value.LastRequest.AddMinutes(GarbageCollectFrequencyInMinutes) < DateTime.Now);
		
		foreach(var kv in oldEntries)
		{
			entries.Remove(kv);
		}
	}
	
	public class Entry
	{
		public string Ip { get; set; }
		
		public int Requests { get; set; }
		
		public DateTime LastRequest { get; set; }
	}
}