[RATIS-1626] Add conf param for purge log

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.4.0, 3.0.0
• Component/s: conf, server
• Assignee: Song Ziyang
• Reporter: Song Ziyang
• Created: 18/Jul/22 15:16
• Updated: 24/Oct/23 18:27
• Resolved: 24/Jul/22 15:46

Description

Add a new conf to control latest n won’t-be-purged logs. It can help applications to balance between the cost of preserving & transferring lagging logs and the cost of transferring snapshot. Intuitively, applications can set n to where (n average logs == a snapshot). 

Issue Links

• is duplicated by: RATIS-562 Add a configurable Purge after Snapshot Policy in Ratis
• links to: GitHub Pull Request #688