RateLimiter

[WeihanLi]

[EdiWang]

I would hope to have something similar to https://github.com/stefanprodan/AspNetCoreRateLimit, that package was not under active development since .NET got it's own rate limiting middleware. However, their new implementation requires Redis, which would be a over-kill for a simple single server application.

[WeihanLi]

API Proposal:

public interface IRateLimiter
{
    Task<RateLimitLease> AcquireAsync(int permitCount = 1, CancellationToken cancellationToken = default);
}

public class RateLimiterOptions
{
    public required int Limit { get; set; }
}

internal abstract class RateLimiter<TOptions>
  where TOptions : RateLimiterOptions
{
    protected RateLimiter(TOptions options)
    {
        Options = options;
    }
    protected TOptions Options { get; }
}

public interface RateLimitLease
{
    bool IsAcquired { get; }
    Timespan? RetryAfter { get; }
    bool TryGetMetadata<T>(string metadataName, [MaybeNull] out T metadata);
}

public class RateLimitLease : RateLimitLease
{
    bool IsAcquired { get; }
    Timespan? RetryAfter { get; }
    bool TryGetMetadata<T>(string metadataName, [MaybeNull] out T metadata)
}

public class ConcurrencyRateLimiter : IRateLimiter
{
}

public class ConcurrencyRateLimiterOptions : RateLimiterOptions {}

public class TokenBucketRateLimiter : IRateLimiter
{
}

public class TokenBucketRateLimiterOptions : RateLimiterOptions
{
    public TimeSpan FillPeriod { get; set; }
    public int TokensPerPeriod { get; set; }
    public bool AutoFill { get; set; }
    public int QueueLimit { get; set; }
}

public class FixedWindowsRateLimiter : IRateLimiter
{
    
}

public class SlidingWindowsRateLimiter : IRateLimiter
{
}

possible Redis-based implementation

public class RedisConcurrencyRateLimiter : ConcurrencyRateLimiter
{
}

public class RedisTokenBucketRateLimiter : TokenBucketRateLimiter
{
}

// public required TimeSpan TimeWindow { get; init; }

public class RedisFixedWindowsRateLimiter : FixedWindowsRateLimiter
{
}

public class RedisSlidingWindowsRateLimiter : SlidingIRateLimiter
{
}

Usage example:

var rateLimiter = new TokenBucketRateLimiter(new TokenBucketRateLimterOptions
{
    Limit = 10    
});