Bench node children

jmh-benchmarks/src/jmh/java/net/minestom/jmh/event/MultiNodeBenchmark.java

@@ -0,0 +1,51 @@
+package net.minestom.jmh.event;
+
+import net.minestom.server.event.Event;
+import net.minestom.server.event.EventNode;
+import org.openjdk.jmh.annotations.*;
+
+import java.util.concurrent.TimeUnit;
+
+@Warmup(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
+@Measurement(iterations = 10, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
+@Fork(3)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@State(Scope.Benchmark)
+public class MultiNodeBenchmark {
+
+    @Param({"0", "1", "3", "10"})
+    public int children;
+
+    private EventNode<Event> node;
+
+    record TestEvent() implements Event {
+    }
+
+    record TestEvent2() implements Event {
+    }
+
+    @Setup
+    public void setup() {
+        node = EventNode.all("node");
+        for (int i = 0; i < children; i++) {
+            var child = EventNode.all("child-" + i);
+            child.addListener(TestEvent.class, e -> {
+                // Empty
+            });
+
+            node.addChild(child);
+
+            // Real-world code are very unlikely to use entirely empty nodes.
+            // This ensures that the handle map is properly lazily initialized to prevent fast exits.
+            child.addListener(TestEvent2.class, e -> {
+                // Empty
+            }).call(new TestEvent2());
+        }
+    }
+
+    @Benchmark
+    public void call() {
+        node.call(new TestEvent());
+    }
+}