refresh

Catches up with what the store's writer has written since this store last read it, and returns whether the state reads see changed. Reads already running, and results already open, keep the state they started on. Calls are serialized: a call waits for one running. Runs on the store's dispatcher.

After the writer flushed its indexes, a refresh reads the writer's unflushed log again, which costs what replaying it at open costs. When it fails, with CorruptionException for damage the writer had synced or a java.io.IOException, reads keep the state they had, and a later call tries again.