[KNOX-2660] Consider using Caffeine cache in DefaultTokenStateService

• Type: Task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.5.0, 1.6.0
• Component/s: Server
• Assignee: Sandor Molnar
• Reporter: Sandor Molnar
• Created: 09/Sep/21 07:11
• Updated: 09/Sep/21 07:11

Description

This is a follow-up Jira of KNOX-2658: in the corresponding PR we agreed that's ok to remove in-memory lookup in the JDBC token state service implementation for expiration time and metadata (the 2 data that can be changed through a token's lifetime).

However, in case of performance issues, we may want to add a more sophisticated in-memory cache in DefaultTokenStateService using Caffeine (like we do in other places within Knox) with a configurable entry TTL and documentation on the side effects of that change (e.g. introducing eventual consistency in HA environments).