AresMUSH
A New Breed of MUSH Server

Reloading Code

Changes to the Ares game engine require a restart, but the plugins can be reloaded while the game is running.

How to Reload

If you’ve only changed plugins, you can reload each plugin while the game is still running by using the load <plugin name> command in-game.

If all you’ve changed are configuration files, the load config command will read them. The config is automatically reloaded when using the Web Portal config editor.

If you’ve changed the Web Portal, you’ll need to re-deploy it through the Admin -> Manage menu on the Web Portal or the website/deploy command in-game.

If you’ve changed the engine, you’ll need to actually shutdown and restart the game before the changes will take effect. You probably shouldn’t be changing the engine, though.

How Code is Loaded

The load command lets you reload the code for a specific plugin.

> load fs3skills
%% Plugin 'fs3skills' loading.  Please wait...
%% Plugin 'fs3skills' (including config, help and locale) reloaded.

To understand the reload feature (and its limitations), it helps to understand a bit about how Ruby loads code.

Take the following example of tinker_cmd.rb:

module AresMUSH
    module Tinker
        class TinkerCmd
        # ... other stuff 
        
        def handle
          client.emit_success "Done!"
        end
    end
end

When Ruby loads this file, it creates a module AresMUSH, then a module AresMUSH::Tinker, then a class TinkerCmd, then it adds the handle method to the command class. The handle method contains a single emit.

Let’s say we change the command’s behavior:

module AresMUSH
    module Tinker
        class TinkerCmd
        # ... other stuff 
        
        def handle
          client.emit_success "Starting!"
          client.emit_success "Definitely Done!"
        end
    end
end

When we reload the tinker plugin, Ares first unloads the old one. Anything in the AresMUSH::Tinker module is deleted from memory so we can start fresh. When Ruby encounters the module Tinker line, it’ll create a new AresMUSH::Tinker module containing the new code. The next time someone uses the tinker command, they’ll get the new behavior.

Loading Pitfalls

The reload functionality works pretty well overall, but there are a few situations that can cause issues.

Database Models

Database models don’t belong to a plugin module - they’re always part of the root AresMUSH module. (There are reasons for this, which we won’t go into here.)

module AresMUSH
  class GameMap < Ohm::Model
    # ... other stuff
  end
end

Since the database models aren’t part of the plugin module, they won’t be unloaded before being reloaded. Because of this, you can add things to database models through a reload, but you can’t remove things.

Module Mix-Ups

Sometimes you’ll accidentally put code in the wrong module. For example:

module AresMUSH
    module Chargen
        class TinkerCmd
        # ...

You wanted TinkerCmd to be in the Tinker module, but instead it ended up in the Chargen module.

Reloading the Tinker module (after fixing the code) will add the AresMUSH::Tinker::TinkerCmd class correctly. But the one in Chargen is still there.

Normally this doesn’t do any harm. Having an extra, unused command laying around the Chargen module doesn’t really matter. But if it were a database model or an interface method, it may cause some unexpected behavior. Just reload the Chargen plugin to fix it.

Killing the Manager

The Manage plugin is the one that provides all the code necessary to load other code. Be extra cautious when making code changes to the Manage plugin. If anything goes haywire when loading it, you’ll find yourself without a Manage plugin … which means you won’t be able to load any other code! The only way to recover from that is to shutdown and restart the game.