Run condition on folder change

[mhofman]

Description of the issue

I understand that SyncthingNative is capable of doing a watch through inotify on shared folders, but that requires the engine to be running, which keeps the network connections going.

I've read the wiki's Info on battery optimization, and it seems the recommended path is to enable the"Sync every hour for 5 minutes" option.

What I'd like is for the Android wrapper to watch itself for changes to the folder shared (since it seems to keep a copy of that info outside the engine), start SyncthingNative after those changes have been detected (probably with a hysteresis similar to the engine), and shutdown after the sync has completed (engine idle for x minutes).

I'm usually interested to fully sync the changes, so the 5 minutes hard limit is kinda strange, like #419 (comment) mentions as well. We could keep a "run for max y minutes" option for people that want to enforce some limit, maybe coupled to a "only if on battery", or "only if on cellular" toggle?

Version Information

• App Version: 1.18.6.0
• Syncthing Version: v1.18.6
• Android Version: Android 11
• Device manufacturer: Google
• Device model: Pixel 5