Rollback preparation fails if required data have been deleted #210
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negokaz
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Jun 1, 2023
...l-cassandra/src/test/scala/lerna/akka/entityreplication/rollback/RaftShardRollbackSpec.scala
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Closes #206
Once data (events or snapshots) have been deleted, a rollback to a timestamp that requires such deleted data is impossible. This PR changes the rollback preparation (
prepareRollback) such that it fails if required data have already been deleted.The rollback preparation checks that each persistent actor can be rolled back (the persistent actor has a consistent state after rollback) based on sequence numbers. These checks involve the following component:
RollbackRequirementsVerifier: for each persistent actor, it verifies whether the rollback is possible.PersistentActorRollback.findRollbackRequirements: for each persistent actor, it finds the possible lowest sequence number such that the persistent actor is consistent after rollbacks.RollbackTimestampHintFinder: it finds a timestamp hint if the rollback is impossible. Rollbacks should specify a newer timestamp than the hint, at least. While the hint might need to be more strictly correct, it helps to know why the given timestamp-based rollback is impossible.