1. Configuration

Project Dependencies

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

The library has a hidden dependency on SLF4J, and you will need to include a dependency and related configuration for a specific logging implementation.

As an example, you could include the following in your project dependencies:

[org.slf4j/slf4j-log4j12 <VERSION>]

If you do not configure logging, you will see some SLF4J warnings output and will not receive logs the underlying circuit breaker library.

Configuration Options

The following table describes the options available when configuring time 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
:cancel-running-future	true	A value indicating whether cancel should be called on the future
:timeout-duration	1000	The number of milliseconds in the timeout duration

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

Global Registry

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

configure-registry! overwrites the existing registry with one containing one or more config values. configure-registry! takes a map of name/config value pairs. When a time 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 time limiters that are created without a providing or naming a config with use this default config.

The function time-limiter! will look up or create a time 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.time-limiter :as tl])

;; The following creates two configs: the default config and the FailFaster
;; config. The default config uses only the defaults and will be used to create
;; time limiters that do not specify a config to use.
(tl/configure-registry! {"default"    {}
                         "FailFaster" {:timeout-duration 500}})


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

;; create a time limiter named :fail-faster using the "FailFaster" config
;; from the registry and store the result in the registry
(tl/time-limiter! :fail-faster "FailFaster")

;; create a time limiter named :custom-config using a custom config map
;; and store the result in the registry
(tl/time-limiter! :custom-config {:cancel-running-future false})

Custom Time Limiters

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

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

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

(ns myproject.core
  (:require [resilience4clj.time-limiter :as tl]))

(def my-limiter (tl/time-limiter :my-limiter {}))