Rate Limiter Strategy

The rate limiter strategy controls the rate of executions to prevent resource exhaustion and ensure fair usage.

RateLimiterStrategyOptions

Configures the rate limiter resilience strategy.

public class RateLimiterStrategyOptions : ResilienceStrategyOptions

Properties

RateLimiter

Func<RateLimiterArguments, ValueTask<RateLimitLease>>?

default:"null"

A rate limiter delegate that produces RateLimitLease instances.If null, the strategy uses a ConcurrencyLimiter created with DefaultRateLimiterOptions.

DefaultRateLimiterOptions

ConcurrencyLimiterOptions

required

The default rate limiter options used when RateLimiter is null.Default configuration:

PermitLimit: 1000
QueueLimit: 0

OnRejected

Func<OnRateLimiterRejectedArguments, ValueTask>?

default:"null"

An event raised when the execution of a user-provided callback is rejected by the rate limiter.

Extension Methods

Add rate limiter strategies to a resilience pipeline:

public static ResiliencePipelineBuilder AddRateLimiter(
    this ResiliencePipelineBuilder builder,
    RateLimiterStrategyOptions options)

public static ResiliencePipelineBuilder<TResult> AddRateLimiter<TResult>(
    this ResiliencePipelineBuilder<TResult> builder,
    RateLimiterStrategyOptions options)

Usage Examples

Using Default Concurrency Limiter

using System.Threading.RateLimiting;

var rateLimiterOptions = new RateLimiterStrategyOptions
{
    DefaultRateLimiterOptions = new ConcurrencyLimiterOptions
    {
        PermitLimit = 100,
        QueueLimit = 50
    },
    OnRejected = args =>
    {
        Console.WriteLine("Rate limit exceeded!");
        return ValueTask.CompletedTask;
    }
};

var pipeline = new ResiliencePipelineBuilder()
    .AddRateLimiter(rateLimiterOptions)
    .Build();

Using Custom Rate Limiter

using System.Threading.RateLimiting;

var tokenBucket = new TokenBucketRateLimiter(new TokenBucketRateLimiterOptions
{
    TokenLimit = 100,
    TokensPerPeriod = 10,
    ReplenishmentPeriod = TimeSpan.FromSeconds(1),
    QueueLimit = 0
});

var rateLimiterOptions = new RateLimiterStrategyOptions
{
    RateLimiter = args => tokenBucket.AcquireAsync(permitCount: 1, args.Context.CancellationToken)
};

var pipeline = new ResiliencePipelineBuilder()
    .AddRateLimiter(rateLimiterOptions)
    .Build();

Sliding Window Rate Limiter

var slidingWindow = new SlidingWindowRateLimiter(new SlidingWindowRateLimiterOptions
{
    PermitLimit = 100,
    Window = TimeSpan.FromMinutes(1),
    SegmentsPerWindow = 6
});

var rateLimiterOptions = new RateLimiterStrategyOptions
{
    RateLimiter = args => slidingWindow.AcquireAsync(permitCount: 1, args.Context.CancellationToken)
};

Built-in Rate Limiters

.NET provides several built-in rate limiters in the System.Threading.RateLimiting namespace:

ConcurrencyLimiter: Limits the number of concurrent executions
TokenBucketRateLimiter: Token bucket algorithm
SlidingWindowRateLimiter: Sliding window algorithm
FixedWindowRateLimiter: Fixed window algorithm

Documentation Index