Watership Down

Watership Down is an example of a Bukkit plugin written in Clojure. It is also endeavoring to be fully functional plugin that lets you track the stats of your players, and grant achievements based on those stats.

Classloader woes

What is there (which isn’t much, mind you) is currently compileable through lein, bundles up a plugin.yml, and sets the classpath in the manifest to a shared clojure lib in ../server/lib/. This is great, but there is a slight problem:

09:10:17 [SEVERE] Could not load 'plugins/watershipdown-0.1.jar' in folder 'plugins': 
java.lang.ExceptionInInitializerError
	at clojure.lang.Namespace.<init>(Namespace.java:34)
	at clojure.lang.Namespace.findOrCreate(Namespace.java:176)
	at clojure.lang.Var.internPrivate(Var.java:149)
	at net.jonnay.watershipdown.WatershipDown.<clinit>(Unknown Source)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:247)
	at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131)
	at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:285)
	at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:200)
	at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:156)
	at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:132)
	at net.minecraft.server.ServerConfigurationManager.<init>(ServerConfigurationManager.java:52)
	at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:148)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:407)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)
Caused by: java.lang.RuntimeException: java.io.FileNotFoundException: Could not locate clojure/core__init.class or clojure/core.clj on classpath: 
	at clojure.lang.Util.runtimeException(Util.java:165)
	at clojure.lang.RT.<clinit>(RT.java:319)
	... 15 more
Caused by: java.io.FileNotFoundException: Could not locate clojure/core__init.class or clojure/core.clj on classpath: 
	at clojure.lang.RT.load(RT.java:430)
	at clojure.lang.RT.load(RT.java:398)
	at clojure.lang.RT.doInit(RT.java:434)
	at clojure.lang.RT.<clinit>(RT.java:316)
	... 15 more

From what I can glean, this has to do with the class loader. One option is to bundle a version of clojure with use-context-classloader set to false, which may work. (But involves building my own clojure.) Another option might be to look into the JavaPlugin class, and over-ride its behavior, especially with regards to the Java Plugin Loader. ( http://jd.bukkit.org/doxygen/d1/ddb/JavaPluginLoader_8java_source.html ) Not sure about that however.

Yet anotehr option involves using a Java delegate to load the clojure directly (but then, what is the point of compiling to java?) Like here http://johnsanda.blogspot.com/2010/11/writing-rhq-plugin-in-clojure.html or even here, which runs clojure through a reader and the evaluator: https://groups.google.com/group/clojure/browse_thread/thread/f0c69735c5a9bd03/1e0dced366af9077?lnk=gst&q=webstart&fwc=1&hl=en

From the Jira ticket here: http://dev.clojure.org/jira/browse/CLJ-260 it looks like we can set the context classloader inside of a subclass of javaplugin (probably called ClojurePlugin, funnily enough). This may have some serious implications with the bukkit classloader however.

Thread.currentThread().setContextClassLoader(loader);

Features, that are coming soon!

Stats are recorded based on typical bukkit events
When an achievement is earned, an event is posted!
If Spout is active, even more events are listened to
Uses a SqLite Database, and maybe MySQL too!
Dynamic Event listening, if I can make it go!

jonnay/Watership-Down

Watership Down

Classloader woes

Features, that are coming soon!