[HOLD for payment 2024-10-11] Optimistic API READ updates are not applied immediately if write requests are queued

[hannojg]

Slack thread

In this PR:

• Make API.read wait on all requests on the SequentialQueue to respond #12219

we introduced for read requests to happen only after any write request has completed. An example for that is this use case:

• You are offline and create a workspace
• then you come online
• You created the workspace optimistically, but because you had some other write requests queued, your READ to get workspace list goes to the server before the WRITE to create the workspace
• The READ to get workspace list uses an Onyx.set, and your optimistic workspace is not included, so it disappears
• A few moments later, your request to create a workspace goes through, and it shows back up

however, due to that change we stopped applying optimistic READ updates immediately. Instead, now, the optimistic updates are only applied once all write requests has finished.

This can cause bugs. One bug for example is here, where we open a new component which fires a READ request on mount. It sets a loading state, and that one is expected to immediately become visible in the UI:

But as the read requests optimistic update is delayed we just see a blank page:

[melvin-bot]

This issue has not been updated in over 15 days. eroding to Monthly issue.

P.S. Is everyone reading this sure this is really a near-term priority? Be brave: if you disagree, go ahead and close it out. If someone disagrees, they'll reopen it, and if they don't: one less thing to do!

[hannojg]

The PR is still being worked on:

• fix: apply optimistic updates from READ requests immediately #48057

I believe this is still relevant as otherwise the user can run into situation with long blank screens / waiting times, as we wait for optimistic updates to be applied while waiting for a network write request.

[hannojg]

PR has been merged to staging, waiting for any regressions…