@mangar2/retry

Abstract

asyncronously retries function calls several times with delay inbetween Prevents parallel retry loops with the same topic .

Contents

• Meta
• Class Retry
  • Parameters
  • Methods
    • on
    • retry
    • stopRetry
    • topicRetry

Meta

File	retry.js
Abstract	asyncronously retries function calls several times with delay inbetween Prevents parallel retry loops with the same topic .
Author	Volker Böhm
Copyright	Copyright ( c ) 2020 Volker Böhm
License	This software is licensed under the GNU LESSER GENERAL PUBLIC LICENSE Version 3 . It is furnished "as is" , without any support , and with no warranty , express or implied , as to its usefulness for any purpose .

Class Retry

new Retry(immediateFirstCall)

Class providing a retry facility calling a callback "count" times asyncronously with a delay inbetween Additionally providing a "topic" based retry ( "topicRetry" ) with the following functionality :

• Asynchronously calles a global callback "count" times with a delay inbetween
• If no global callback is provided , it calls a callback prior registrated to the topic
• If topicRetry is called with a still running existing retry loop for the same topic , this existing is terminated .

Example

const retry = new Retry()
// prints 5 times hello world, with a delay of 1 second between each output
retry.retry(5, 1000, () => console.log("hello world"))
// prints hello1, world, hello2, world, hello2
retry.topicRetry('hello', 2, 1000, () => console.log("hello1"))
retry.topicRetry('world', 2, 1000, () => console.log("world"))
retry.topicRetry('hello', 2, 1000, () => console.log("hello2"))

Retry Parameters

Name	Type	Attribute	Default	Description
immediateFirstCall	boolean	optional	true	true , if the first call should happen immediately

Retry Methods

on

on (topic, callback)

Registers a callback for a topic

on Parameters

Name	Type	Description
topic	string	topic to register a callback
callback	function(	called on matching topic on retries

on throws

Type	Description
Error	if the callback is not 'function'

retry

async retry (count, delayInMilliseconds, callback) => {Promise}

Calls a callback function multiple times and waits between the calls .

retry Parameters

Name	Type	Description
count	number	quantity of retries
delayInMilliseconds	number	amount of milliseconds to wait between retries
callback	function(loopNumber	function called on each retry

retry returns

Type	Description
Promise	promise resolving , when all callbacks are done

stopRetry

stopRetry (topic)

Stops a retry loop

stopRetry Parameters

Name	Type	Description
topic	string	name of the retry topic

topicRetry

async topicRetry (topic, count, delayInMilliseconds, callback) => {Promise}

Calls a callback function multiple times and waits between the calls . If you call "retry" with the same topic a second time , it will stop the running retry loop with the same topic

topicRetry Parameters

Name	Type	Description
topic	string	name of the topic to retry
count	number	quantity of retries
delayInMilliseconds	number	amount of milliseconds to wait between retries
callback	function(	function called on each retry

topicRetry returns

Type	Description
Promise	promise resolving , when all callbacks are done