40 lines
1.5 KiB
C#
40 lines
1.5 KiB
C#
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namespace RegexBot.Modules;
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/// <summary>
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/// Helper class for managing rate limit data.
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/// More accurately, this class holds entries, not allowing the same entry to be held more than once until a specified
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/// amount of time has paspsed since the entry was originally tracked; useful for a rate limit system.
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/// </summary>
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class RateLimit<T> {
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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 uint Timeout { get; }
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#pragma warning disable CS8714
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private Dictionary<T, DateTime> Entries { get; } = new Dictionary<T, DateTime>();
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#pragma warning restore CS8714
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public RateLimit() : this(DefaultTimeout) { }
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public RateLimit(uint timeout) => Timeout = timeout;
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/// <summary>
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/// 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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/// <returns>True if the given value is permitted by the rate limiter.</returns>
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public bool IsPermitted(T value) {
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if (Timeout == 0) return true;
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// Take a moment to clean out expired entries
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var now = DateTime.Now;
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var expired = Entries.Where(x => x.Value.AddSeconds(Timeout) <= now).Select(x => x.Key).ToList();
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foreach (var item in expired) Entries.Remove(item);
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if (Entries.ContainsKey(value)) {
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return false;
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} else {
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Entries.Add(value, DateTime.Now);
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return true;
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}
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}
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}
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