6c986faa3f
Regression from Phase 15: new players connecting for the FIRST time got
kicked with 'PlayerSync: another server is finalizing your save. Please
reconnect in a few seconds.' before they ever saw the world.
Root cause: the Phase 15 atomic CAS was
UPDATE player_data SET last_server=?, online=1, logout_started_at=NULL
WHERE uuid=? AND (online=0 OR last_server=?)
For a brand-new player the player_data row does not exist yet — the WHERE
clause matches zero rows and executePreparedUpdateRet returns 0. The
surrounding check treated 'claim == 0' as 'another server beat us', so
it kicked the player. But it was really 'no row to update yet' — the
store(player, true) call further down the flow is what INSERTs the row.
Fix: the poll loop already detects row-missing via rsCheck.next() == false
and breaks out. Thread that signal through as isNewPlayer and skip the
CAS entirely when it's set. The subsequent !playerExists branch picks up
the new player and INSERTs the row with the correct state.
No impact on the cross-server race safety: existing-row players still run
the full CAS; only the true-first-connection path is unblocked. Zero risk
of duplication / data loss — new players have nothing to duplicate or lose.
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| .github | ||
| compat-mods | ||
| gradle/wrapper | ||
| src/main | ||
| .gitattributes | ||
| .gitignore | ||
| build.gradle | ||
| CHANGELOG.md | ||
| docker-compose.yml | ||
| ERROR_LOG.md | ||
| gradle.properties | ||
| gradlew | ||
| gradlew.bat | ||
| LICENSE | ||
| README.md | ||
| settings.gradle | ||
| TEST_PROCEDURE_v2.1.5.html | ||
PlayerSync
PlayerSync is a Minecraft Forge mod that synchronizes player data across multiple servers using a MySQL backend. It allows players to maintain their inventory, equipment, experience, advancements, and more when moving between servers in a network.
Mod Support
Any other mods support is also possible.
Development Setup
Database Setup (Docker)
A docker-compose.yml file is provided for easily setting up a MariaDB database instance for development testing.
- Make sure Docker is installed.
- Inside your work directory run:
This will download the MariaDB image (if not already present) and start a database container in the background.docker compose up -d - Stoppinng the Database
docker compose down
Data Persistence: The database uses a Docker volume, ensuring your data persists even if you stop and restart the containers.
Database Management Tool
The docker-compose.yml also includes an Adminer service, a lightweight database management tool.
- Access Adminer in your web browser at http://localhost:8080.
- Log in using the server with
- username:
playersync - database:
playersync - password: see docker-compose.yml
- username:
For debugging purposes, you can enable use_legacy_serialization to have readable database fields. This can cause crashes and unintended side-effects. Do not enable this on a production server if not absolutely necessary!
Running the Mod
The project uses Gradle for building and running. Use the provided Gradle wrapper (gradlew for Linux/macOS, gradlew.bat for Windows).
- Make sure that the MySQL database you configured is running.
- Run the Server
or on Windows:./gradlew runServer
This task compiles the mod and starts a dedicated Minecraft server instance with the mod loaded in the.\gradlew.bat runServerrundirectory. - Run the Client
or on Windows:./gradlew runClient.\gradlew.bat runClient