This article tries summarizes my thought process in an understandable way.
What should it do?
We want to achieve Multi-Server Compatibility. That requires the files (worlds and templates) to be stored externally. The most practical solution for a big server is probably SFTP, but for smaller servers which lack on resources and only want a single server, it should be possible without setting up SFTP.
Dealing with Race Conditions
By having multiple Realms-Servers, conflicts about the data ownership might arise. The scenario involves race conditions where multiple servers might attempt to acquire the same lock simultaneously. A robust locking mechanism is needed to ensure that only one server acquires the lock at any time to maintain data integrity and prevent conflicts.
Redis allows lock management through atomic operations:
- The
SET key value NX EX 300command is central:- NX ensures the lock is only set if the key doesn’t already exist (no overwrite).
- EX 300 sets an expiration time (300 seconds here) to avoid indefinite locks (preventing deadlocks).
- The
EXPIREcommand refreshes a lock if it’s still held and needs to extend its lifetime. - This ensures a “first come, first serve” mechanism, where only one server can “get the dish” at a time, and the lock eventually times out if not explicitly released or refreshed. This is important for unresponding realm instances.
Todo
To be continued…