36 lines
1 KiB
C#
36 lines
1 KiB
C#
using System.Collections.Concurrent;
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using System.Threading.RateLimiting;
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using NodaTime;
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using NodaTime.Extensions;
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namespace Foxnouns.Backend.Services;
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public class EmailRateLimiter
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{
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private readonly ConcurrentDictionary<string, RateLimiter> _limiters = new();
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private readonly FixedWindowRateLimiterOptions _limiterOptions =
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new() { Window = TimeSpan.FromHours(2), PermitLimit = 3 };
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private RateLimiter GetLimiter(string bucket) =>
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_limiters.GetOrAdd(bucket, _ => new FixedWindowRateLimiter(_limiterOptions));
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public bool IsLimited(string bucket, out Duration retryAfter)
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{
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RateLimiter limiter = GetLimiter(bucket);
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RateLimitLease lease = limiter.AttemptAcquire();
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if (!lease.IsAcquired)
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{
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retryAfter = lease.TryGetMetadata(MetadataName.RetryAfter, out TimeSpan timeSpan)
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? timeSpan.ToDuration()
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: default;
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}
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else
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{
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retryAfter = Duration.Zero;
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}
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return !lease.IsAcquired;
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}
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}
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