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