From 4f66fd793b99f173cea117c1bb22592c417aef17 Mon Sep 17 00:00:00 2001
From: Nassim Jahnke <nassim@njahnke.dev>
Date: Sun, 25 Aug 2024 18:59:48 +0200
Subject: [PATCH] Go back to fast entity data list iteration and mutation This
 is a fairly hot method and the array list cannot be modified outside of the
 already managed event cancellation and provided extra list

---
 .../viaversion/rewriter/EntityRewriter.java          | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/common/src/main/java/com/viaversion/viaversion/rewriter/EntityRewriter.java b/common/src/main/java/com/viaversion/viaversion/rewriter/EntityRewriter.java
index eb18e8f80..74a3a4f73 100644
--- a/common/src/main/java/com/viaversion/viaversion/rewriter/EntityRewriter.java
+++ b/common/src/main/java/com/viaversion/viaversion/rewriter/EntityRewriter.java
@@ -110,7 +110,11 @@ public abstract class EntityRewriter<C extends ClientboundPacketType, T extends
     public void handleEntityData(final int entityId, final List<EntityData> dataList, final UserConnection connection) {
         final TrackedEntity entity = tracker(connection).entity(entityId);
         final EntityType type = entity != null ? entity.entityType() : null;
-        for (final EntityData entityData : dataList.toArray(EMPTY_ARRAY)) { // Copy the list to allow mutation
+
+        // Iterate over indexed list to allow for removal and addition of elements, decrease current index and size if an element is removed
+        int size = dataList.size();
+        for (int i = 0; i < size; i++) {
+            final EntityData entityData = dataList.get(i);
             EntityDataHandlerEvent event = null;
             for (final EntityDataFilter filter : entityDataFilters) {
                 if (!filter.isFiltered(type, entityData)) {
@@ -125,13 +129,15 @@ public abstract class EntityRewriter<C extends ClientboundPacketType, T extends
                     filter.handler().handle(event, entityData);
                 } catch (final Exception e) {
                     logException(e, type, dataList, entityData);
-                    dataList.remove(entityData);
+                    dataList.remove(i--);
+                    size--;
                     break;
                 }
 
                 if (event.cancelled()) {
                     // Remove entity data, and break current filter loop
-                    dataList.remove(entityData);
+                    dataList.remove(i--);
+                    size--;
                     break;
                 }
             }