Multiple app updates can race

[bobrippling]

If I have 5 apps with updates available, but I want to only update 4 of them (e.g. I'm currently testing a beta of the 5th), then if I click on all 4 apps' update buttons at once, the updates appear to race instead of being queued, possibly causing corruption

[gfwilliams]

Thanks - yes, this is definitely something that's an issue - same with just clicking to install >1 app at once.

I believe the UART library does to some queueing of writes, but because we're writing packets now I'm not sure that helps, and the situation could be worse than before.

I'm not quite sure the best way to work around this - open to ideas... Maybe at the start of each promise chain for update/install/etc we do executeWhenIdle(() => promiseChain)?

executeWhenIdle(fn) would have to call fn when idle, and then fn would have to return the promise chain so that executeWhenIdle would then know when that task had finished.

Does that make sense?

[bobrippling]

I suppose even if UART queued writes, we'd need application-level queuing, otherwise the data copied for, e.g. app1.js could interleave with app2.js

The promise chain is what I was thinking too, we could get around needing to know when we're idle by having a currentTransfer promise. We initialise it to Promise.resolve(), then on button press we do: currentTransfer = currentTransfer.then(installAppForThisButton)

Or we just have a list of pending operations and iterate through them?

[gfwilliams]

I like the currentTransfer option - I think putting the currentTransfer=currentTransfer.then operation in a function might give us some nice benefits:

• an error wouldn't break out of the whole promise chain
• we could remove a lot duplication around the adding/removing progress messages and showing errors
• I've seen cases where an app upload fails and it's left with the spinning 'progress' icon on it - we could ensure we always get rid of those after an operation has completed to attempt to work around that.

[bobrippling]

Cool - I guess we would fail the promise chain though, unless we did this right?

currentTransfer = currentTransfer.then(...).catch(<decide whether to resume or rethrow>)

But yes - it'd nicely handle progress and error display, along with that spinning icon, that I've also seen

[gfwilliams]

Thanks - yes, that sounds good. I'll take a look at this later today

[gfwilliams]

Ok, I've just pushed some changes which I think should help substantially. It feels like they tidy things up a bit too - I've been clicking around and on the whole they work well.

Only think I'd say is right now the swirly progress icons disappear after the first app is updated - but that's kind of an edge case. Please can you take a look and see if it works ok for you when you get a chance?

[bobrippling]

Ah great! Works well with what I've tried, I'll see if I can spot anything over the next few days too - thanks!

[bobrippling]

But yeah I suppose we can sort the spinning icons more easily once the promise stuff is solid :)

[gfwilliams]

Great! We did have one issue with backup/restore but I fixed that yesterday.

I'll close this for now then - it's on banglejs.com/apps as well and no complaints yet :)

[bobrippling]

Awesome - been using this more and it makes the app loader very "hands off" and pleasant for multiple updates, thanks!