Currently, decryption happens on the main thread. As such, downloading resources in parallel gives the DecryptionWorker more to decrypt (and thus decryption of everything may be slower).
I also suspect that downloading resources in parallel to notes/notebooks makes downloading sync slower because of rate limiting.
Another option would be to sync notes and notebooks first, then resources. (Though if a user opens a just-decrypted note, perhaps its resources could be downloaded sooner.)
But does it really make sync slower?
I'm currently testing this.
- Without resources, a full sync (iOS/OneDrive/E2EE) takes roughly 6 minutes.
- With resources, a sync of all notes takes roughly 8 minutes. Resources continue to download after that however (still downloading 25 minutes later).
So it seems that sync times are similar.
A note on background sync
There is at least one library available that may do background sync (or something similar):
I wasn't able to get it to start a background task though (perhaps the version of the library I was using wasn't compatible with the version of React Native Joplin uses?).
A while back, there was also a pull request that implemented background sync natively, though just for Android.
The difficulties here are:
- Running a task in the background.
- If background sync runs at the same time as the main application, it could cause data corruption (Joplin makes the assumption that only one instance of the application is running at a time).
- Thus, also canceling the background sync task when Joplin comes to the foreground and resuming it/starting a new one when Joplin goes to the background.
There seems to be a library available from the same project that prevents the screen from sleeping:
Thus, a simpler alternative could be to have an "initial sync" screen that keeps the screen on.