RegexBot/Modules-SelfHosted/AutoScriptResponder/RateLimit.cs
Noikoio 530a4ae1b6 Add AutoScriptResponder
I'm not particularly proud of this.
2018-11-04 20:40:57 -08:00

54 lines
1.8 KiB
C#

using System;
using System.Collections.Generic;
namespace Kerobot.Modules.AutoScriptResponder
{
/// <summary>
/// Helper class for managing rate limit data.
/// </summary>
class RateLimit<T>
{
public const ushort DefaultTimeout = 20; // Skeeter's a cool guy and you can't convince me otherwise.
public ushort Timeout { get; }
private readonly object _lock = new object();
private Dictionary<T, DateTime> _table = new Dictionary<T, DateTime>();
public RateLimit() : this(DefaultTimeout) { }
public RateLimit(ushort timeout) => Timeout = timeout;
/// <summary>
/// 'Permit?' - Checks if the given value is permitted through the rate limit.
/// Executing this method may create a rate limit entry for the given value.
/// </summary>
/// <param name="id"></param>
/// <returns>True if the given value is permitted by the rate limiter.</returns>
public bool Permit(T value)
{
if (Timeout == 0) return true;
lock (_lock)
{
Clean();
if (_table.ContainsKey(value)) return false;
_table.Add(value, DateTime.Now);
}
return true;
}
/// <summary>
/// Clean up expired entries.
/// </summary>
private void Clean()
{
var now = DateTime.Now;
var newTable = new Dictionary<T, DateTime>();
foreach (var item in _table)
{
// Copy items that have not yet timed out to the new dictionary. Discard the rest.
if (item.Value.AddSeconds(Timeout) > now) newTable.Add(item.Key, item.Value);
}
lock (_lock) _table = newTable;
}
}
}