During HMSFollower start up, when retrieving HMS full snapshot, also need to ensure point-in-time snapshot consistency.
It should be:
- Read current HMS notification ID_initial
- Read HMS metadata state
- Read current notification ID_new
- If ID_initial != ID_new then discard the current state and goto 1.
Use configurable property: sentry.hms.snapshot.retries.max.count for max number of retry.
Ideally, during fetching full snapshot, there should be no write activity on the HMS.