Component used: Room InvalidationTracker

Version used: 2.2.5

Devices/Android versions reproduced on: Android Studio emulator with Android R DP 2.1

Sample project: https://github.com/bubenheimer/invalidationtrackerbug

I am seeing consistency problems with the updates from InvalidationTracker when using JournalMode.TRUNCATE.

In my production app some updates are skipped - the observer is never called for a percentage of updates to a rarely updated table, causing the associated app screen to not get updated to the current state. I debugged into it and believe that this is associated with a lack of transactionality in InvalidationTracker.mRefreshRunnable. JournalMode.WRITE_AHEAD_LOGGING uses a transaction here, while JournalMode.TRUNCATE does not. Reads and writes of the table update log are disassociated, leaving the door open to overwriting recent changes to the log.
In the provided sample project I see the opposite effect, however: a lot of extra updates are triggered by InvalidationTracker with JournalMode.TRUNCATE. I am not sure what the underlying mechanism is for this behavior.

Exact effects are timing-related. The bottom line is that InvalidationTracker looks essentially broken for JournalMode.TRUNCATE. On the other hand I do not see significant issues with JournalMode.WRITE_AHEAD_LOGGING.