Add Event#hasListener, remove unused junk

fabric-api-base/src/main/java/net/fabricmc/fabric/api/event/Event.java

@@ -88,4 +88,15 @@ public void register(Identifier phase, T listener) {
 	public void addPhaseOrdering(Identifier firstPhase, Identifier secondPhase) {
 		// This is not abstract to avoid breaking existing Event subclasses, but they should really not be subclassing Event.
 	}
+
+	/**
+	 * Returns whether the event has any listeners. Useful for skipping steps related to
+	 * event invocation, such as making context objects, when the event has no listeners.
+	 * This method is unnecessary when the only code guarded by this check is the event invocation.
+	 *
+	 * @return whether the event has any listeners
+	 */
+	public boolean hasListener() {
+		return true;
+	}
 }

fabric-api-base/src/main/java/net/fabricmc/fabric/api/event/EventFactory.java

@@ -126,14 +126,11 @@ public static boolean isProfilingEnabled() {
 	}
 
 	/**
-	 * Invalidate and re-create all existing "invoker" instances across
-	 * events created by this EventFactory. Use this if, for instance,
-	 * the profilingEnabled field changes.
+	 * Does nothing.
 	 *
 	 * @deprecated Do not use, will be removed in a future release.
 	 */
 	@Deprecated(forRemoval = true)
 	public static void invalidate() {
-		EventFactoryImpl.invalidate();
 	}
 }

fabric-api-base/src/main/java/net/fabricmc/fabric/impl/base/event/ArrayBackedEvent.java

@@ -50,7 +50,7 @@ class ArrayBackedEvent<T> extends Event<T> {
 		update();
 	}
 
-	void update() {
+	private void update() {
 		this.invoker = invokerFactory.apply(handlers);
 	}
 
@@ -123,4 +123,9 @@ public void addPhaseOrdering(Identifier firstPhase, Identifier secondPhase) {
 			rebuildInvoker(handlers.length);
 		}
 	}
+
+	@Override
+	public boolean hasListener() {
+		return this.handlers.length > 0;
+	}
 }

fabric-api-base/src/main/java/net/fabricmc/fabric/impl/base/event/EventFactoryImpl.java

@@ -16,37 +16,17 @@
 
 package net.fabricmc.fabric.impl.base.event;
 
-import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.MethodType;
-import java.lang.reflect.Array;
-import java.lang.reflect.Method;
-import java.lang.reflect.Modifier;
-import java.lang.reflect.Proxy;
-import java.util.Collections;
-import java.util.Set;
 import java.util.function.Function;
 
-import com.google.common.collect.MapMaker;
-
 import net.minecraft.util.Identifier;
 
 import net.fabricmc.fabric.api.event.Event;
 
 public final class EventFactoryImpl {
-	private static final Set<ArrayBackedEvent<?>> ARRAY_BACKED_EVENTS
-			= Collections.newSetFromMap(new MapMaker().weakKeys().makeMap());
-
 	private EventFactoryImpl() { }
 
-	public static void invalidate() {
-		ARRAY_BACKED_EVENTS.forEach(ArrayBackedEvent::update);
-	}
-
 	public static <T> Event<T> createArrayBacked(Class<? super T> type, Function<T[], T> invokerFactory) {
-		ArrayBackedEvent<T> event = new ArrayBackedEvent<>(type, invokerFactory);
-		ARRAY_BACKED_EVENTS.add(event);
-		return event;
+		return new ArrayBackedEvent<>(type, invokerFactory);
 	}
 
 	public static void ensureContainsDefault(Identifier[] defaultPhases) {
@@ -68,58 +48,4 @@ public static void ensureNoDuplicates(Identifier[] defaultPhases) {
 			}
 		}
 	}
-
-	// Code originally by sfPlayer1.
-	// Unfortunately, it's slightly slower than just passing an empty array in the first place.
-	private static <T> T buildEmptyInvoker(Class<T> handlerClass, Function<T[], T> invokerSetup) {
-		// find the functional interface method
-		Method funcIfMethod = null;
-
-		for (Method m : handlerClass.getMethods()) {
-			if ((m.getModifiers() & (Modifier.STRICT | Modifier.PRIVATE)) == 0) {
-				if (funcIfMethod != null) {
-					throw new IllegalStateException("Multiple virtual methods in " + handlerClass + "; cannot build empty invoker!");
-				}
-
-				funcIfMethod = m;
-			}
-		}
-
-		if (funcIfMethod == null) {
-			throw new IllegalStateException("No virtual methods in " + handlerClass + "; cannot build empty invoker!");
-		}
-
-		Object defValue = null;
-
-		try {
-			// concert to mh, determine its type without the "this" reference
-			MethodHandle target = MethodHandles.lookup().unreflect(funcIfMethod);
-			MethodType type = target.type().dropParameterTypes(0, 1);
-
-			if (type.returnType() != void.class) {
-				// determine default return value by invoking invokerSetup.apply(T[0]) with all-jvm-default args (null for refs, false for boolean, etc.)
-				// explicitCastArguments is being used to cast Object=null to the jvm default value for the correct type
-
-				// construct method desc (TLjava/lang/Object;Ljava/lang/Object;...)R where T = invoker ref ("this"), R = invoker ret type and args 1+ are Object for each non-"this" invoker arg
-				MethodType objTargetType = MethodType.genericMethodType(type.parameterCount()).changeReturnType(type.returnType()).insertParameterTypes(0, target.type().parameterType(0));
-				// explicit cast to translate to the invoker args from Object to their real type, inferring jvm default values
-				MethodHandle objTarget = MethodHandles.explicitCastArguments(target, objTargetType);
-
-				// build invocation args with 0 = "this", 1+ = null
-				Object[] args = new Object[target.type().parameterCount()];
-				//noinspection unchecked
-				args[0] = invokerSetup.apply((T[]) Array.newInstance(handlerClass, 0));
-
-				// retrieve default by invoking invokerSetup.apply(T[0]).targetName(def,def,...)
-				defValue = objTarget.invokeWithArguments(args);
-			}
-		} catch (Throwable t) {
-			throw new RuntimeException(t);
-		}
-
-		final Object returnValue = defValue;
-		//noinspection unchecked
-		return (T) Proxy.newProxyInstance(EventFactoryImpl.class.getClassLoader(), new Class[]{handlerClass},
-			(proxy, method, args) -> returnValue);
-	}
 }