RegexBot/Module/AutoRespond/RateLimitCache.cs

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using System;
using System.Collections.Generic;
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namespace Noikoio.RegexBot.Module.AutoRespond
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{
/// <summary>
/// Stores rate limit settings and caches.
/// </summary>
class RateLimitCache
{
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public const ushort DefaultTimeout = 20; // this is Skeeter's fault
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private readonly ushort _timeout;
private Dictionary<ulong, DateTime> _cache;
public ushort Timeout => _timeout;
/// <summary>
/// Sets up a new instance of <see cref="RateLimitCache"/>.
/// </summary>
public RateLimitCache(ushort timeout)
{
_timeout = timeout;
_cache = new Dictionary<ulong, DateTime>();
}
/// <summary>
/// Checks if a "usage" is allowed for the given value.
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/// Items added to cache will be removed after the number of seconds specified in <see cref="Timeout"/>.
/// </summary>
/// <param name="id">The ID to add to the cache.</param>
/// <returns>True on success. False if the given ID already exists.</returns>
public bool AllowUsage(ulong id)
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{
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if (_timeout == 0) return true;
lock (this)
{
Clean();
if (_cache.ContainsKey(id)) return false;
_cache.Add(id, DateTime.Now);
}
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return true;
}
private void Clean()
{
var now = DateTime.Now;
var clean = new Dictionary<ulong, DateTime>();
foreach (var kp in _cache)
{
if (kp.Value.AddSeconds(Timeout) > now)
{
// Copy items that have not yet timed out to the new dictionary
clean.Add(kp.Key, kp.Value);
}
}
_cache = clean;
}
}
}