[ZOOKEEPER-1794] Add hash check to transaction history in quorum servers

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.5.0
• Component/s: quorum
• Release Note: The snapshot file name will be updated by adding also the hash. That means a name like "snapshot.100001.123533" where 100001 is the zxid and 123533 is the hash. The server will continue to be able to read files without the hash in the name.
• Assignee: Germán Blanco
• Reporter: Germán Blanco
• Created: 14/Oct/13 06:15
• Updated: 03/Feb/22 08:50

Description

The goal of this task is to add a hash number to each transaction in the transaction history. This hash number will depend on the entire transaction history. This hash number will be the same in all members of the quorum, since it shall have the same result if the members have the same transaction history. That means that there will be no need to send any new information between members of the quorum, during the broadcast phase. The hash number will be checked by the leader when learners try to connect, and it shall also be sent together with the snapshot during synchronisation. If the hash number does not match, the synchronisation shall be done with a snapshot in order to overwrite the conflicts in the transaction history.