Load island data off the main thread to fix periodic lag spikes

[tastybento]

Problem

Server admins reported periodic lag spikes (~160–970 ms, up to a 1,012 ms tick) every refresh cycle, profiled to:

TopBlockManager.refreshAll
  -> AOneBlockHook.getAllIslandData
  -> JSONDatabaseHandler.loadObjects

The refresh timer is a sync Bukkit task, and getAllIslandData() delegates to the game mode's getAllIslands(), which is a full synchronous database read (Database#loadObjects()) — it reads and deserializes every island record ever created, on the main thread, every cycle (default 5 min). The cost scales with island count and disk latency, and doubles when both AOneBlock and ChunkBlock are hooked.

Fix

refresh(hook) now runs getAllIslandData() on an async task (pure file I/O + JSON parsing — the same call Level already makes async) and hops back to the main thread only for the cheap part in the new processIslandData(): island registry lookups, player/permission checks, and swapping in the new top-ten list. Placeholder snapshots update per hook as each async load completes instead of once after a blocking refreshAll().

This moves essentially the entire refresh cost off the tick loop with no behavior change to the top ten, placeholders, or panel.

Other changes

• CommonTestSetup stubs the scheduler to run both legs of the async→sync hop inline so the existing tests stay synchronous.
• Bumped build.version to 2.1.1; updated CLAUDE.md to document the async/sync split.

Testing

• mvn test — all 44 tests pass.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Um9roAZ8pVAqp6TZEMBjMr

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
81.8% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud