move reflect fields in Extension to ExtensionClassLoader (#1478)

src/main/java/net/minestom/server/extensions/DiscoveredExtension.java

@@ -116,7 +116,7 @@ public final class DiscoveredExtension {
     void createClassLoader() {
         Check.stateCondition(classLoader != null, "Extension classloader has already been created");
         final URL[] urls = this.files.toArray(new URL[0]);
-        classLoader = new ExtensionClassLoader(this.getName(), urls);
+        classLoader = new ExtensionClassLoader(this.getName(), urls, this);
     }
 
     @NotNull

src/main/java/net/minestom/server/extensions/Extension.java

@@ -17,16 +17,6 @@ import java.util.HashSet;
 import java.util.Set;
 
 public abstract class Extension {
-    // Set by reflection
-    @SuppressWarnings("unused")
-    private DiscoveredExtension origin;
-    // Set by reflection
-    @SuppressWarnings("unused")
-    private Logger logger;
-    // Set by reflection
-    @SuppressWarnings("unused")
-    private EventNode<Event> eventNode;
-
     /**
      * List of extensions that depend on this extension.
      */
@@ -56,9 +46,16 @@ public abstract class Extension {
 
     }
 
+    ExtensionClassLoader getExtensionClassLoader() {
+        if (getClass().getClassLoader() instanceof ExtensionClassLoader extensionClassLoader) {
+            return extensionClassLoader;
+        }
+        throw new IllegalStateException("Extension class loader is not an ExtensionClassLoader");
+    }
+
     @NotNull
     public DiscoveredExtension getOrigin() {
-        return origin;
+        return getExtensionClassLoader().getDiscoveredExtension();
     }
 
     /**
@@ -68,11 +65,11 @@ public abstract class Extension {
      */
     @NotNull
     public Logger getLogger() {
-        return logger;
+        return getExtensionClassLoader().getLogger();
     }
 
     public @NotNull EventNode<Event> getEventNode() {
-        return eventNode;
+        return getExtensionClassLoader().getEventNode();
     }
 
     public @NotNull Path getDataDirectory() {

src/main/java/net/minestom/server/extensions/ExtensionClassLoader.java

@@ -1,7 +1,11 @@
 package net.minestom.server.extensions;
 
 import net.minestom.server.MinecraftServer;
+import net.minestom.server.event.Event;
+import net.minestom.server.event.EventNode;
 import org.jetbrains.annotations.NotNull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.InputStream;
 import java.net.URL;
@@ -11,13 +15,18 @@ import java.util.List;
 
 public final class ExtensionClassLoader extends URLClassLoader {
     private final List<ExtensionClassLoader> children = new ArrayList<>();
+    private final DiscoveredExtension discoveredExtension;
+    private EventNode<Event> eventNode;
+    private Logger logger;
 
-    public ExtensionClassLoader(String name, URL[] urls) {
+    public ExtensionClassLoader(String name, URL[] urls, DiscoveredExtension discoveredExtension) {
         super("Ext_" + name, urls, MinecraftServer.class.getClassLoader());
+        this.discoveredExtension = discoveredExtension;
     }
 
-    public ExtensionClassLoader(String name, URL[] urls, ClassLoader parent) {
+    public ExtensionClassLoader(String name, URL[] urls, ClassLoader parent, DiscoveredExtension discoveredExtension) {
         super("Ext_" + name, urls, parent);
+        this.discoveredExtension = discoveredExtension;
     }
 
     @Override
@@ -55,4 +64,29 @@ public final class ExtensionClassLoader extends URLClassLoader {
 
         return null;
     }
+
+    public DiscoveredExtension getDiscoveredExtension() {
+        return discoveredExtension;
+    }
+
+    public EventNode<Event> getEventNode() {
+        if (eventNode == null) {
+            eventNode = EventNode.all(discoveredExtension.getName());
+            MinecraftServer.getGlobalEventHandler().addChild(eventNode);
+        }
+        return eventNode;
+    }
+
+    public Logger getLogger() {
+        if (logger == null) {
+            logger = LoggerFactory.getLogger(discoveredExtension.getName());
+        }
+        return logger;
+    }
+
+    void terminate() {
+        if (eventNode != null) {
+            MinecraftServer.getGlobalEventHandler().removeChild(eventNode);
+        }
+    }
 }

src/main/java/net/minestom/server/extensions/ExtensionManager.java

@@ -5,8 +5,6 @@ import net.minestom.dependencies.DependencyGetter;
 import net.minestom.dependencies.ResolvedDependency;
 import net.minestom.dependencies.maven.MavenRepository;
 import net.minestom.server.ServerProcess;
-import net.minestom.server.event.Event;
-import net.minestom.server.event.EventNode;
 import net.minestom.server.utils.PropertyUtils;
 import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.ApiStatus;
@@ -17,7 +15,6 @@ import org.slf4j.LoggerFactory;
 
 import java.io.*;
 import java.lang.reflect.Constructor;
-import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.net.URL;
 import java.nio.file.Path;
@@ -322,47 +319,6 @@ public class ExtensionManager {
             return null;
         }
 
-        // Set extension origin to its DiscoveredExtension
-        try {
-            Field originField = Extension.class.getDeclaredField("origin");
-            originField.setAccessible(true);
-            originField.set(extension, discoveredExtension);
-        } catch (IllegalAccessException e) {
-            // We made it accessible, should not occur
-        } catch (NoSuchFieldException e) {
-            LOGGER.error("Main class '{}' in '{}' has no description field.", mainClass, extensionName, e);
-            return null;
-        }
-
-        // Set logger
-        try {
-            Field loggerField = Extension.class.getDeclaredField("logger");
-            loggerField.setAccessible(true);
-            loggerField.set(extension, LoggerFactory.getLogger(extensionClass));
-        } catch (IllegalAccessException e) {
-            // We made it accessible, should not occur
-            serverProcess.exception().handleException(e);
-        } catch (NoSuchFieldException e) {
-            // This should also not occur (unless someone changed the logger in Extension superclass).
-            LOGGER.error("Main class '{}' in '{}' has no logger field.", mainClass, extensionName, e);
-        }
-
-        // Set event node
-        try {
-            EventNode<Event> eventNode = EventNode.all(extensionName); // Use the extension name
-            Field loggerField = Extension.class.getDeclaredField("eventNode");
-            loggerField.setAccessible(true);
-            loggerField.set(extension, eventNode);
-
-            serverProcess.eventHandler().addChild(eventNode);
-        } catch (IllegalAccessException e) {
-            // We made it accessible, should not occur
-            serverProcess.exception().handleException(e);
-        } catch (NoSuchFieldException e) {
-            // This should also not occur
-            LOGGER.error("Main class '{}' in '{}' has no event node field.", mainClass, extensionName, e);
-        }
-
         // add dependents to pre-existing extensions, so that they can easily be found during reloading
         for (String dependencyName : discoveredExtension.getDependencies()) {
             Extension dependency = extensions.get(dependencyName.toLowerCase());
@@ -730,9 +686,7 @@ public class ExtensionManager {
         ext.preTerminate();
         ext.terminate();
 
-        // Remove event node
+        ext.getExtensionClassLoader().terminate();
-        EventNode<Event> eventNode = ext.getEventNode();
-        serverProcess.eventHandler().removeChild(eventNode);
 
         ext.postTerminate();