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 |