Tus10 auto-retry the upload when back online

[oliverpool]

This PR adds the option (default true) to "auto-retry" uploads when the use is back online.

Only the uploads already started, not completed and not paused are retried.

[arturi]

tus-js-client has built-in retries, but not related to navigator.online directly.

This PR seems like a good approach, but it would be cool if we had a second opinion from @Acconut and @kvz maybe. Should this be an uploader plugin setting/feature or global?

[oliverpool]

tus-js-client has built-in retries, but not related to navigator.online directly.

That's right. As you point out, it stops retrying when the navigator is offline.
Maybe this should be split into two options:

• retryDelays behaving like the tus-js-client (abort when offline)
• resumeWhenOnline (naming is hard) to auto-retry when the navigator is back online (if supported - try every x seconds otherwise)

[Acconut]

Personally, I am in favor of the retryDelays and resumeWhenOnline options, as suggested by @oliverpool. Are you thinking of adding this feature only for the tus uploader or all uploaders?

[arturi]

Two options seem good with me too.

Are you thinking of adding this feature only for the tus uploader or all uploaders?

Yeah, that‘s what I’m asking, would it make sense for Multipart and, say future S3 uploader too?

[Acconut]

For multipart uploads, only retrying makes sense as this operation is not resumable. In the case of a possible S3 uploader both could be useful.

[oliverpool]

resumeWhenOnline can be renamed to retryWhenOnline (for non-resumable uploads).

For me, the main goal of those two options is to guarantee that everything will be done to complete the upload without requiring user action.

[tim-kos]

I have implemented this for Transloadit's jQuery SDK v3 the other week. A few bits to share:

1. I named the event "reconnect", instead of "back-online". And then "disconnect" for disconnections. They go very well together naming-wise.

2. I didn't make it an option when to retry/resume when reconnected. I just check every 3 seconds if we are back online and if so, I resume immediately. Less options/choice is more sometimes.

Just FYI. 👍

[arturi]

@tim-kos thanks for sharing! Do you listen to online and offline window events? I wonder if there is a need then to check when back online if browser emits the event? I guess there is a possibility of missing it or something.

[arturi]

Merged this, sorry for long delay. Thank you @oliverpool! Let’s test it in battle and add options as we go.