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Async / Await exponential retry


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Purpose

Minimalist, efficient and performance focused retry system. Basically it helps developer to retry a function with a specific interval, exponential factor etc.

No dependency.

Compatibility

/!\ This module use async/await syntax, this is why you must have node 7.6+.

Supported and tested : >= 7.6

Version Supported Tested
20.x yes yes
18.x yes yes
16.x yes yes
14.x yes yes
12.x no yes
10.x no yes
9.x no yes
8.x no yes
>= 7.6 no yes

Installation

$ npm install async-await-retry --save

Usage

Basic usage

const retry = require('async-await-retry');

const func = async () => {return new Promise((resolve) => resolve('OK'))};

try {
    const res = await retry(func)
} catch (err) {
    console.log('The function execution failed !')
}

Sync function syntax

const retry = require('async-await-retry');

const func = () => {...};

try {
    const res = await retry(func)
    console.log(res) // output : OK
} catch (err) {
    console.log('The function execution failed !')
}

Anonymous function style

const retry = require('async-await-retry');

try {
    const res = await retry(async () => {
      return new Promise((resolve) => resolve('OK'))
    })
    
    console.log(res) // output : OK
} catch (err) {
    console.log('The function execution failed !')
}

Callback function style

const retry = require('async-await-retry');

try {
    const res = await retry((arg1, cb) => {
        ....
        cb(err, data); // send err as first argument
    }, ["arg1"], {isCb: true});
} catch (err) {
    console.log('The function execution failed !')
}

Options

## retry(function, [args], [config])

  • function : function to retry in case of error
  • args : your function's parameters in case you don't use callback style
  • config : an object containing all retry process options

options

Option description  Default value
retriesMax Maximum number of retries 3
interval Delay in ms between two tentatives 0
exponential Will the interval increase exponentially ? true
maxBackoff Maximum delay before to retry (with exponential) 30s
factor The exponential factor to use 2
jitter Random jitter in ms to add to the interval 0
isCb Old callback function style ? false
onAttemptFail User's callback to manage retry system default fallback

An example of custom options :

const retry = require('async-await-retry');

try {
    const res = await retry(async () => {
      return new Promise((resolve) => resolve('OK'))
    }, null, {retriesMax: 4, interval: 100, exponential: true, factor: 3, jitter: 100})
    
    console.log(res) // output : OK
} catch (err) {
    console.log('The function execution failed !')
}

onAttemptFail

This method can be used to manage, by yourself, the retry system. It's called when an error occurred and before to retry. This method can have three behaviors:

  • you can throw an error
  • if it returns truthy value then normal retry system continues
  • if it returns falsy value then the retry system stop
const retry = require('async-await-retry');

try {
    const res = await retry(MyfuncToRetry, null, {
        onAttemptFail: (data) => {
            // do some stuff here, like logging errors
        }
    });
} catch (err) {
    console.log('The function execution failed !')
}

The data argument is an object that can be described like this:

Property description
error The current error object
currentRetry The current retry value
retriesMax Maximum number of retries
interval Delay in ms between two tentatives
exponential Will the interval increase exponentially ?
factor The exponential factor to use
jitter Random jitter in ms to add to the interval
maxBackoff Maximum delay before to retry

Test

$ npm test

Coverage report can be found in coverage/.