Retrying Concurrency Tasks

I’ve been playing around with the Premier League Fantasy Football API in the evenings recently and came across a problem with their API.

The small app I’ve built needs to make requests to a number of different end points to load data. I noticed that sometimes these requests return a 200 status but fail to return their payload!

This results in a broken app. I went searching for a solution that could detect a failed request and try again (in almost all cases the 2nd request does return it’s payload)

Ember Concurrency Retryable

Enter the ember-concurrency-retryable plugin!

import Service from '@ember/service';
import { task } from 'ember-concurrency';
import { ExponentialBackoffPolicy } from 'ember-concurrency-retryable';

const backoffPolicy = new ExponentialBackoffPolicy({
  multiplier: 1.5,
  minDelay: 30,
  maxDelay: 400,
});

export default class FplApiService extends Service {

  getLeagueData = task({ retryable: backoffPolicy }, async () => {

      const result = await axios.get(LEAGUE_DETAILS_API);

      if (!result.data) {
        throw new Error('Did not get payload');
      }

      // process the data
    }
  });

}

The above getLeagueData task now throws an error if the response did not contain valid data, this causes the task to be retryed according to the backoff policy.