@clappr/retry-utils

Retry Utils

This lib aims to apply retry patterns for various needed situations. The definitions were inspired by the retry implementation of Shaka Player.

$ npm i retry-utils

Usage

retryPromise - Implements retries for a callback function with exponential backoff, returning a resolved promise if successeded and a rejected promise if doesn't.

Configuration:

retryParameters: {
  action: 'Callback to be executed', (*)
  maxAttempts: 'The maximum number of attempts that should be retried'
  baseDelay: 'The delay before the first retry, in milliseconds',
  backOffFactor: 'The multiplier for successive retry delays'
  retryableErrors: 'A array specifying which HTTP status should be at retry flow' (**)
}

(*) Mandatory fields.

(**) To use the retryableErrors property you must pass the status code into the error object, like demonstrated in Examples section (getSomething method).

The retryPromise method apply a fuzz factor of 50% in either direction. So if the ideal delay is 1000ms, the actual delay will be randomly chosen between 500ms and 1500ms.

The returned promise should have the follow content:

When resolved: A object with the resource and the retry history flow, like:

{
  retryResponse: 'Hey! I as successfull in the third attempt!'
  retryHistory: [
    attempt_1 : { retryError: 'Failed at first' },
    attempt_2 : { retryError: 'Failed at second' }
  ]
}

When rejected: A object with the error and the retry history flow, like:

{
  retryError: 'Failed at my last attempt, sorry :('
  retryHistory: [
    attempt_1 : { retryError: 'Failed at first' },
    attempt_2 : { retryError: 'Failed at second' },
    attempt_3 : { retryError: 'Failed at my last attempt, sorry :(' }
  ]
}

Examples:

retryPromise:

import { retryPromise } from 'retry-utils'

const getSomething = () => {
  return fetch(`http://httpbin.org/status/500`)
    .then((response) => {
      if (response.ok) return response
      throw new Error({ statusCode: response.status })
    })
}

let retryParameters: {
  action: getSomething,
  maxAttempts: 5,
  baseDelay: 1000,
  backOffFactor: 3,
  retryableErrors: [500, 501, 502]
}

retryPromise(retryParameters)
  .then((data) => console.log('Retry success ', data))
  .catch((error) => console.log('Retry error ', error))