Cronjure

Cronjure is a thin Clojure wrapper for the popular cron-utils library.

Installation

Leiningen

[cronjure "0.1.1"]

Deps.edn

{cronjure {:mvn/version "0.1.1"}}

Usage

(require '[cronjure.core :refer :all])

Define a custom cron definition

(def my-cron-definition
  (build-definition
    with-seconds
    (with-minutes
      (with-valid-range 0 60)
      (with-int-mapping 60 0))
    with-hours
    with-day-of-month
    with-months
    (with-day-of-week
      supports-l
      supports-question-mark)))

Create a cron instance

Creating a cron instance requires a cron definition, pre-defined definitions can be found under cronjure.definitions.

(def my-cron-instance
  (build-instance my-cron-definition
    (with-second (on 59))
    (with-minute (between 15 30))
    (with-hour (on 10))
    (with-dow (on 6 cronjure.special-characters/l))
    (with-month always)))

String representation

(as-string my-cron-instance) ; => "59 15-30 10 * 6L"

Describe

Takes an optional locale, uses the default locale if not specified.

(describe my-cron-instance) ; => "every minute between 10:15 and 10:30 last Saturday of every month"

(describe my-cron-instance (java.util.Locale/FRENCH)) ; => "chaque minute entre 10:15 et 10:30 dernier samedi de chaque mois"

Execution date/time

(next-execution-date my-cron-instance) ; => java.time.ZonedDateTime

(last-execution-date my-cron-instance) ; => java.time.ZonedDateTime

Two similar functions are also provided which return instances of a java.time.Duration.

(time-to-next-execution my-cron-instance) ; => java.time.Duration

(time-since-last-execution my-cron-instance) ; => java.time.Duration

A format can be optionally supplied.

(time-to-next-execution my-cron-instance :minutes) ; => e.g. 42

(time-to-next-execution my-cron-instance :seconds) ; => e.g. 2520

Parsing

Cron instances can also be created using strings.

(->> "0/30 55 18 ? * 1"
     (parse cronjure.definitions/quartz)
     describe
; => "every 30 seconds at 55 minute at 18 hour at Sunday day"

Field information

Information about specific fields can be retrieved from either a cron definition/instance.

(get-instance-field my-cron-instance :minute)
; => {:order 1,
;    :expression "15-30",
;    :constraints {:start-range 0, :end-range 60, :special-chars ["NONE"]}}

(get-definition-field my-cron-definition :minute)
;=> {:optional false,
;    :constraints {:start-range 0, :end-range 60, :special-chars ["NONE"]}}