[IGNITE-17334] Basic volatile RAFT log storage

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.0.0-beta1
• Component/s: persistence
• Labels: ignite-3
• Epic Link: In-memory store
• Assignee: Roman Puchkovskiy
• Reporter: Roman Puchkovskiy
• Reviewer: Kirill Tkalenko
• Created: 07/Jul/22 19:02
• Updated: 13/Oct/22 12:01
• Resolved: 17/Aug/22 14:12

Description

The storage should contain the following components:

1. An elastic (but with possible hard-limit) in-memory storage for log entries. On this iteration it will be on-heap data structure (for instance, a skip list). Later, we'll build something better (like an off-heap implementation, maybe using pagemem).
2. An algorithm for determining when the in-memory storage cannot accept new entries. On this iteration, the only supported algorithm will be simply limiting the store by the number of stored entries. Later we will add something smarter, like the total size of the stored entries and adaptive algorithms.
3. Logic for spilling out to disk. This should not be implemented on this iteration, but it will be implemented later, in IGNITE-17336

Issue Links

• split from: IGNITE-16655 Volatile RAFT log for pure in-memory storages
• links to: GitHub Pull Request #939