1. Configuration

Project Dependencies

resilience4clj-ratelimiter is distributed through Clojars with the identifier tessellator/resilience4clj-ratelimiter. You can find the version information for the latest release at https://clojars.org/tessellator/resilience4clj-ratelimiter.

Configuration Options

The following table describes the options available when configuring rate limiters as well as default values. A config is a map that contains any of the keys in the table. Note that a config without a particular key will use the default value (e.g., {} selects all default values).

Configuration Option	Default Value	Description
:timeout-duration	5000	The number of milliseconds to wait for permission to execute
:limit-refresh-period	500	The number of nanoseconds in a given refresh period
:limit-for-period	50	The number of permissions available in one limit refresh period

A config can be used to configure the global registry or a single rate limiter when it is created.

Global Registry

This library creates a single global registry. The registry may contain config values as well as rate limiter instances.

configure-registry! overwrites the existing registry with a new registry containing one or more config values. configure-registry! takes a map of name/config value pairs. When a rate limiter is created, it may refer to one of these names to use the associated config. Note that the name :default (or "default") is special in that rate limiters that are created without providing or naming a config will use this default config.

The function rate-limiter! will look up or create a rate limiter in the global registry. The function accepts a name and optionally the name of a config or a config map.

(ns myproject.core
  (:require [resilience4clj.rate-limiter :as rl])

;; The following creates two configs: the default config and the MoreAllowances
;; config. The default config uses only the defaults and will be used to create
;; rate limiters that do not specify a config to use.
(rl/configure-registry! {"default"    {}
                         "MoreAllowances" {:limit-for-period 100}})


;; create a rate limiter named :name using the "default" config from the
;; registry and store the result in the registry
(rl/rate-limiter! :name)

;; create a rate-limiter named :more-allowed using the "MoreAllowances" config
;; from the registry and store the result in the registry
(rl/rate-limiter! :more-allowed "MoreAllowances")

;; create a rate limiter named :custom-config using a custom config map
;; and store the result in the registry
(rl/rate-limiter! :custom-config {:timeout-duration 1000})

Custom Rate Limiters

While convenient, it is not required to use the global registry. You may instead choose to create rate limiters and manage them yourself.

In order to create a rate limiter that is not made available globally, use the rate-limiter function, which accepts a name and config map.

The following code creates a new rate limiter with the default config options.

(ns myproject.core
  (:require [resilience4clj.rate-limiter :as rl]))

(def my-limiter (rl/rate-limiter :my-limiter {}))