Muddy is a side project of mine and an evolution of my previous Go based MUD, gomud. While gomud was clever, it was too clever for it’s own good and had too many antipatterns for Go, specifically around locks and the interpreter. Muddy will instead focus on correct message passing between goroutines via channels to avoid locks when updating/writing objects, a supervisor based goroutine manager using the wonderful Suture library, and a more simplified interpreter system.
Much of the code that comprises muddy will come from gomud, with most of the low level construct handling being refactored.
I use this project both to work on a passion of mine, text based games, and to further my skills as a developer. This project ends up being where I try a lot of different things/expand my software architecture skills as a result.
The idea mehind muddy is to emulate an erlang-like actor system, but much more lightweight and flexible, while maintaining a Go-like programming style.
Each object in the world is an actor running under a supervisor, which includes players, rooms, objects, etc. These objects can only be modified by messages passed into the object via a channel. The channel implementation is hidden from the caller, and just appears as normal methods on the object type.
This ensures that only a single goroutine is responsible for updating an objects properties, simplifying the issue of complex object interaction and reentrant locks, which Go does not support. Reading a property of an object (i.e. player health, etc) is a simple read of the variable that defines it, wrapped in a read lock. This is also hidden from the called in various helper functions.
Player input is handled by the player’s actor, and is passed to an interpreter via a channel. This interpreter acts as a nexus for player commands. For now, all commands will be interpreted in the same goroutine, effectively making all commands across all players serial in nature. In the future, this may be done in parallel across users once a strategy for dealing with deadlocks has been worked through.