---
title: erl
summary: Edge rate limiter and supporting functions.
url: https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/erl/
---

**Kind:** Module  
**Package:** fastly 0.13.1  
**Path:** `fastly::erl`

Edge rate limiter and supporting functions.

## Structs

| Name | Summary |
| --- | --- |
| [ERL](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/erl/struct.ERL/) | An edge rate limiter which includes a ratecounter and a penaltybox. |
| [Penaltybox](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/erl/struct.Penaltybox/) | A penaltybox that can be used with the edge rate limiter or stand alone for adding and checking if some entry is in the data set. |
| [RateCounter](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/erl/struct.RateCounter/) | A rate counter that can be used with a edge rate limiter or stand alone for counting and rate calculations |

## Enums

| Name | Summary |
| --- | --- |
| [CounterDuration](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/erl/enum.CounterDuration/) | To be used for picking the duration in a rate counter lookup_count call |
| [ERLError](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/erl/enum.ERLError/) | Errors that can arise during ERL operations. |
| [RateWindow](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/erl/enum.RateWindow/) | To be used for picking the window in a rate counter lookup_rate or a ERL check_rate |