[GitHub] [geode] mcmellawatt opened pull request #3939: GEODE-7088: Copy message to isolate filter info calculation

["mcmellawatt (GitHub)" <gi...@apache.org>]

This fix is to handle a very specific race condition scenario as described here:

Subscription HA is enabled and a server is providing a client queue image to a peer (serializing the queue). Meanwhile, a client is also just finished client subscription registration with that same server and is recalculating its filter info to determine if the client needs the event. Recalculating the filter info results in the client message in the HAContainer to be mutated, which causes a ConcurrentModificationException to occur in the GII provider thread. The fix we landed on is to make a copy of the client update message when recalculating the filter info in the drain logic from the client registration queue. This guarantees that there will be no shared state between the GII thread and the client registration thread, and it also covers the case that multiple clients are calculating the filter info on the same event and potentially in contention.

Co-authored-by: Ryan McMahon <rm...@pivotal.io>
Co-authored-by: Donal Evans <do...@pivotal.io>

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