@mangar2/retry NPM

Abstract

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


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