photoncloud-monorepo/flaredb/specs/002-raft-features/research.md
centra 8f94aee1fa Fix R8: Convert submodule gitlinks to regular directories
- Remove gitlinks (160000 mode) for chainfire, flaredb, iam
- Add workspace contents as regular tracked files
- Update flake.nix to use simple paths instead of builtins.fetchGit

This resolves the nix build failure where submodule directories
appeared empty in the nix store.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2025-12-09 16:51:20 +09:00

23 lines
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Markdown

# Research: Raft Core Replication (002-raft-features)
## Decisions
- **Raft library**: Use `raft` (tikv/raft-rs 0.7, prost-codec).
- *Rationale*: Battle-tested implementation, already wired in repo; supports necessary APIs for storage/transport.
- *Alternatives considered*: `openraft` (heavier refactor), custom Raft (too risky/time-consuming).
- **Log/State persistence**: Persist log entries, hard state, conf state in RocksDB CFs (`raft_log`, `raft_state`).
- *Rationale*: RocksDB already provisioned and used; column families align with separation of concerns; durable restart semantics.
- *Alternatives considered*: In-memory (unsafe for recovery), separate files (adds new IO path, no benefit).
- **Cluster scope**: Fixed 3-node membership for this phase; no dynamic add/remove.
- *Rationale*: Matches spec clarification; reduces scope to core replication/recovery; simpler correctness surface.
- *Alternatives considered*: Joint consensus/dynamic membership (out of scope now).
- **Transport**: Continue with tonic/prost gRPC messages for Raft network exchange.
- *Rationale*: Existing RaftService in repo; shared proto tooling; avoids new protocol surface.
- *Alternatives considered*: custom TCP/UDP transport (unnecessary for current goals).
- **Testing approach**: Unit tests for storage/persistence; single-node campaign/propose; multi-node integration harness to validate majority commit and follower catch-up.
- *Rationale*: Aligns with constitution Test-First; exercises durability and replication behaviors.
- *Alternatives considered*: manual ad-hoc testing (insufficient coverage).