What is a retrie?

A retrie is a retrier like you'd find from bluebird-retry or async-retry, but returns a modified promise that lets you track or cancel the retry process from both within the retry and externally. A good example of when this would be useful is if you have a case where you are reaching out to multiple data sources for something in a race scenario, and some data sources involve retries, this allows you to cancel the rest of them upon any succeeding.

Installation

npm install --save retrie

Usage

First, import retrie:

import { retrie } from 'hodash.retrie';

You can then use retrie to create a retried operation:

const operation = () => fetch('https://api.example.com/data');
const retried = retrie(operation, { maxRetries: 3, minTimeout: 1000 });

This creates a new operation that will be retried up to 3 times, with a minimum delay of 1000 milliseconds between attempts.

The retried object has a promise property containing the promise for the resolution of its function.

const result = await retried.promise;

// or

retried.promise
.then((result) => {})
.catch(err => {});

Canceling

You can cancel a retry process from happening from within your function or from outside.

// From outside
const retried = retrie(operation, { maxRetries: 3, minTimeout: 1000 });
retried.cancel();

// From inside

retrie(({ cancel, retries }) => {
  // Maybe something happened where in this particular case, after n retries, we cancel early
  if (retries > 3 && thingHappened) cancel();
});

// Specific cancel error
retrie(({ cancel, retries }) => {
  // We can pass cancel an error that will be thrown in place of the last error the retrie encountered.
  if (retries > 3 && thingHappened) cancel(new Error('Special error));
});

Scenario

Race Scenario

Consider a scenario where you are reaching out to multiple data sources in a race scenario. If any of the sources resolve successfully, you might want to cancel the rest:

const source1 = retrie(fetchDataFromSource1, { maxRetries: 3, minTimeout: 1000 });
const source2 = retrie(fetchDataFromSource2, { maxRetries: 3, minTimeout: 1000 });

const result = await Promise.race([source1.promise, source2.promise])
.catch(err => {}); // Swallow any errors from race failures

// Cancel any active retries (the "winner" will be unaffected)
source1.cancel();
source2.cancel();

Contributing

We welcome contributions! Please see our contributing guidelines for more information.

License

MIT