[API Proposal]: AggregateRateLimiter

[TonyValenti]

Background and motivation

It would be nice to be able to AND (and possibly OR) rate limiters together.

For example, "I want a rate limiter that allows no more than 10 requests per second and no more than 2 concurrent requsts".

API Proposal

namespace System.Threading.RateLimiting;

public class AggregateRateLimiter : RateLimiter
{
  public AggregateRateLimiter(IEnumerable<RateLimiter> Children);
}

API Usage

var Limiter1 = ...;
var Limiter2 = ...;
var Limiter = new AggregateRateLimiter([Limit1, Limit2]);

Alternative Designs

People can always roll their own.

Risks

None that I can think of.

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Issue Details

---

Background and motivation

It would be nice to be able to AND (and possibly OR) rate limiters together.

For example, "I want a rate limiter that allows no more than 10 requests per second and no more than 2 concurrent requsts".

API Proposal

namespace System.Threading.RateLimiting

public class AggregateRateLimiter : RateLimiter
{
  public AggregateRateLimiter(IEnumerable<RateLimiter> Children);
}

API Usage

var Limiter1 = ...;
var Limiter2 = ...;
var Limiter = new AggregateRateLimiter([Limit1, Limit2]);

Alternative Designs

People can always roll their own.

Risks

None that I can think of.

Author:	TonyValenti
Assignees:	-
Labels:	api-suggestion, area-System.Threading
Milestone:	-

[stephentoub]

cc: @BrennanConroy

[BrennanConroy]

I'm not against it, we didn't add this for non-partitioned rate limiters because it's not particularly hard to write yourself. But we do have prior-art for adding similar API recently: #93623

I have seen a few similar asks as well on other issues.

API would probably be:

+ public class ChainedRateLimiter : RateLimiter
+ {
+     public ChainedRateLimiter(params RateLimiter[] limiters);
+ }

or

public abstract class RateLimiter
{
+    public static RateLimiter CreateChained(params RateLimiter[] limiters);
}

[TonyValenti]

Is there any chance someone could add this? I could really use it.

[SbiCA]

Is there any chance someone could add this? I could really use it.

@TonyValenti +1 on that could you please also add your thoughts here since you provided a draft of how this could look like. It seems there are a few other people wanting this feature.

dotnet/aspnetcore#54051

[TonyValenti]

The link you listed is for ASP.NET stuff with rate limiting. My use case is in a desktop app where we still need to limit requests to an API. Personally, I prefer RateLimiter.Aggregate but whatever the name is, I dont really care, I just could really use it.

[SbiCA]

@BrennanConroy would it make sense to separate the Asp.Net core part into an own issue then?

[BrennanConroy]

Background and motivation

It would be nice to be able to AND rate limiters together.

For example, "I want a rate limiter that allows no more than 10 requests per second and no more than 2 concurrent requests".

PartitionedRateLimiter has static PartitionedRateLimiter CreateChained(params PartitionedRateLimiter[] limiters); already.

Recent similar API is public static TextWriter CreateBroadcasting(params TextWriter[] writers); #93623

API Proposal

namespace System.Threading.RateLimiting;

+ public sealed class ChainedRateLimiter : RateLimiter
+ {
+    public ChainedRateLimiter(ReadOnlySpan<RateLimiter> limiters);
+ }

API Usage

var Limiter1 = new ConcurrencyLimiter(new ConcurrencyLimiterOptions() { PermitLimit = 5 };
var Limiter2 = new TokenBucketRateLimiter(new TokenBucketRateLimiterOptions() { TokenLimit = 10, ReplenishPeriod = TimeSpan.FromSeconds(1), TokensPerPeriod = 2 };
var Limiter = new ChainedRateLimiter([Limiter1, Limiter2]);

Alternative Designs

public abstract class RateLimiter
{
+    public static RateLimiter CreateChained(ReadOnlySpan<RateLimiter> limiters);
}

+ public sealed class AggregateRateLimiter : RateLimiter
+ {
+     public AggregateRateLimiter(ReadOnlySpan<RateLimiter> limiters);
+ }

Risks

None.