Only complete initialization after userId is properly set

[gabrielgarciagava]

Summary

Currently, if we initialize the plugin via Amplitude.getInstance() and try to get userId from it via Amplitude.getInstance().getUserId() right after, the userId is not set yet, because the initialization happens in a background thread and there is not a proper way to know when it is completed.

I've seen a initCompletionBlock that can be used for that on the iOS SDK, but I couldn't find one in the Android one. So maybe a change on the Android SDK would also be needed to achieve this.

Motivations

Since we don't know when the userId will be ready, we need to wait some arbitrary amount of time. Since we use the presence of the userId to make some initialization decisions, if by any reason the amplitude initialization takes longer (e.g. some database migration), we will take the wrong initialization route.

[gabrielgarciagava]

I have the impression that this was achieved with version 4.0.0. The new swift SDK is used. In the new SDK, looks like the initialization is synchronous, and the isBuilt future completed when the methodChannel call to init completes.

Can someone from Amplitude team confirm? Feel free to close the ticket.

[chungdaniel]

Hey @gabrielgarciagava, this is correct for iOS and Android currently, but not currently the case for web.

On the browser side, since JS is single-threaded, we have it async. I've spoken with my team and it seems like users that rely on waiting for initialization on web will usually await for synchronization before calling getUserId. This isn't currently possible on Flutter as I did not return a promise in the initialization block when implementing web support for our Flutter SDK 4. I'll add an item to our backlog to add waiting for initialization of web to complete as a config option in the meantime 🙂