PollyRateLimiter

[](https://www.nuget.org/packages/PollyRateLimiter/)

Convenience extension methods for Polly v8 resilience pipelines.

Polly v8 ships with AddConcurrencyLimiter out of the box, but leaves FixedWindow, SlidingWindow, and TokenBucket as bring-your-own. This package fills that gap with one-liner extension methods for all three strategies on top of System.Threading.RateLimiting.

Install

dotnet add package PollyRateLimiter

Usage

using PollyRateLimiter;

// Fixed window: 100 requests per second
var pipeline = new ResiliencePipelineBuilder()
    .AddFixedWindowRateLimiter(permitLimit: 100, window: TimeSpan.FromSeconds(1))
    .Build();

// Sliding window: 100 requests per second, smoothed into 4 segments
var pipeline = new ResiliencePipelineBuilder()
    .AddSlidingWindowRateLimiter(permitLimit: 100, window: TimeSpan.FromSeconds(1), segmentsPerWindow: 4)
    .Build();

// Token bucket: burst up to 200, replenish 50 per second
var pipeline = new ResiliencePipelineBuilder()
    .AddTokenBucketRateLimiter(tokenLimit: 200, tokensPerPeriod: 50, replenishmentPeriod: TimeSpan.FromSeconds(1))
    .Build();

Queue limit

By default, executions that exceed the limit are rejected immediately (queueLimit: 0). Pass a positive value to queue them instead:

var pipeline = new ResiliencePipelineBuilder()
    .AddFixedWindowRateLimiter(permitLimit: 10, window: TimeSpan.FromSeconds(1), queueLimit: 5)
    .Build();

OnRejected callback

Use the optional configure callback to attach an OnRejected handler or change other RateLimiterStrategyOptions:

var pipeline = new ResiliencePipelineBuilder()
    .AddTokenBucketRateLimiter(
        tokenLimit: 100,
        tokensPerPeriod: 20,
        replenishmentPeriod: TimeSpan.FromSeconds(1),
        configure: opts => opts.OnRejected = args =>
        {
            logger.LogWarning("Rate limit exceeded. RetryAfter: {RetryAfter}", args.Lease.TryGetMetadata(MetadataName.RetryAfter, out var retry) ? retry : TimeSpan.Zero);
            return ValueTask.CompletedTask;
        })
    .Build();

Generic builder

All methods work with ResiliencePipelineBuilder<T> too:

var pipeline = new ResiliencePipelineBuilder<HttpResponseMessage>()
    .AddFixedWindowRateLimiter(permitLimit: 50, window: TimeSpan.FromSeconds(1))
    .AddRetry(new RetryStrategyOptions<HttpResponseMessage>())
    .Build();

Comparison with Polly built-ins

Strategy	Polly built-in	PollyRateLimiter
Concurrency	AddConcurrencyLimiter(maxConcurrency)	—
Fixed window	❌	AddFixedWindowRateLimiter(permits, window)
Sliding window	❌	AddSlidingWindowRateLimiter(permits, window)
Token bucket	❌	AddTokenBucketRateLimiter(capacity, perPeriod, period)

Support

If PollyRateLimiter simplifies your rate limiting setup, consider supporting the project:

💼 Need .NET resilience help? Visit solidqualitysolutions.com for consulting and architecture services.

| PollyMailKit | MailKit SMTP email client | | PollyAzureQueueStorage | Azure Queue Storage QueueClient | | PollyHangfire | Hangfire IBackgroundJobClient |

Also by the same author

🌐 swevo.github.io

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License

MIT