recoverWith and switch

Hey there!

I’ve encountered a problem, where I’m not sure if it’s my code or a bug. I have created a helper function called retry, which takes a stream and returns the same stream altered, so that it automatically retries on errors with an exponential backoff.

This is the helper function:

retry

export function retry(createOriginalStream, { delay = 1000, exponentialDelay } = {}) {
  let currentDelay = exponentialDelay || delay;
  const $original = createOriginalStream().multicast();

  $original
    .take(1)
    .recoverWith(() => most.empty())
    .forEach(() => {
      currentDelay = delay;
    });

  return $original
    .recoverWith(error =>
      most.just()
        .delay(currentDelay)
        .map(() =>
          retry(createOriginalStream, { delay, exponentialDelay: currentDelay * 2 })
        )
        .switch()
    );
}

This is how it’s used:

failure case

most.combine((someValue, someBoolean) =>
  someBoolean
    ? retry(() => createStream(someValue))
    : most.empty()
  , someValueStream, someBooleanStream)
  .switch()

If someBoolean changes from true to false and the stream is failing, it keeps retrying although there shouldn’t be any listeners. Each time someBoolean switches another failing stream is added trying to recover.

I’m not sure if I’m doing something wrong or if switch fails to unsubscribe from the new recovered streams returned by recoverWith.

Any help is appreciated. 😃

[Sinewyk]

Not sure this helps, but I asked about a retry function a “long” time ago, and this is what it looks like

const retry = (n, stream) => stream.recoverWith(e => n === 0 ? most.throwError(e) : retry(n - 1, stream));

I had to dig it up the gitter history, now I saved it as a gist for a quick lookup.

Seems to do the job.

[briancavalier]

@maxhoffmann Closing this, but please reopen if you need.

@Sinewyk Thanks for posting that retry. I added it to the Recipes wiki.