Clear entity data on world change in world tracker

api/src/main/java/com/viaversion/viaversion/api/data/entity/EntityTracker.java

@@ -67,6 +67,11 @@ public interface EntityTracker {
      */
     void removeEntity(int id);
 
+    /**
+     * Clears stored entity types and data.
+     */
+    void clearEntities();
+
     /**
      * Returns the stored entity data if an entity with the id is tracked, else null.
      * If no data has been initialized yet, it will be done and returned by this method.
@@ -101,8 +106,8 @@ public interface EntityTracker {
     void setClientEntityId(int clientEntityId);
 
     /**
-     * Returns the current world section height.
-     * Always 16 for sub 1.17 worlds.
+     * Returns the current world section height (block height / 16).
+     * This is always 16 for sub 1.17 worlds.
      *
      * @return current world section height
      */
@@ -128,4 +133,18 @@ public interface EntityTracker {
      * @param currentMinY minimum y of the current world
      */
     void setCurrentMinY(int currentMinY);
+
+    /**
+     * Returns the name of the world the player is currently in.
+     *
+     * @return world name of the current world
+     */
+    @Nullable String currentWorld();
+
+    /**
+     * Sets the name of the world the player is currently in.
+     *
+     * @param currentWorld name of the current world
+     */
+    void setCurrentWorld(String currentWorld);
 }

common/src/main/java/com/viaversion/viaversion/data/entity/EntityTrackerBase.java

@@ -37,6 +37,7 @@ public class EntityTrackerBase implements EntityTracker, ClientEntityIdChangeLis
     private int clientEntityId = -1;
     private int currentWorldSectionHeight = 16;
     private int currentMinY;
+    private String currentWorld;
 
     public EntityTrackerBase(UserConnection connection, @Nullable EntityType playerType) {
         this(connection, playerType, false);
@@ -81,6 +82,7 @@ public class EntityTrackerBase implements EntityTracker, ClientEntityIdChangeLis
         return entityData.get(id);
     }
 
+    //TODO Soft memory leak: Remove entities on respawn in protocols prior to 1.18 (1.16+ only when the worldname is different)
     @Override
     public void removeEntity(int id) {
         entityTypes.remove(id);
@@ -89,6 +91,14 @@ public class EntityTrackerBase implements EntityTracker, ClientEntityIdChangeLis
         }
     }
 
+    @Override
+    public void clearEntities() {
+        entityTypes.clear();
+        if (entityData != null) {
+            entityData.clear();
+        }
+    }
+
     @Override
     public int clientEntityId() {
         return clientEntityId;
@@ -108,9 +118,6 @@ public class EntityTrackerBase implements EntityTracker, ClientEntityIdChangeLis
         this.clientEntityId = clientEntityId;
     }
 
-    /**
-     * @return amount of chunk sections of the current world (block height / 16)
-     */
     @Override
     public int currentWorldSectionHeight() {
         return currentWorldSectionHeight;
@@ -121,9 +128,6 @@ public class EntityTrackerBase implements EntityTracker, ClientEntityIdChangeLis
         this.currentWorldSectionHeight = currentWorldSectionHeight;
     }
 
-    /**
-     * @return absolute minimum y coordinate of the current world
-     */
     @Override
     public int currentMinY() {
         return currentMinY;
@@ -133,4 +137,14 @@ public class EntityTrackerBase implements EntityTracker, ClientEntityIdChangeLis
     public void setCurrentMinY(int currentMinY) {
         this.currentMinY = currentMinY;
     }
+
+    @Override
+    public @Nullable String currentWorld() {
+        return currentWorld;
+    }
+
+    @Override
+    public void setCurrentWorld(final String currentWorld) {
+        this.currentWorld = currentWorld;
+    }
 }

common/src/main/java/com/viaversion/viaversion/rewriter/EntityRewriter.java

@@ -362,7 +362,14 @@ public abstract class EntityRewriter<T extends Protocol> extends RewriterBase<T>
         return trackerAndRewriterHandler(null);
     }
 
-    protected PacketHandler worldDataTrackerHandler(int nbtIndex) {
+    /**
+     * Returns a packet handler storing height, min_y, and name of the current world.
+     * If the client changes to a new world, the stored entity data will be cleared.
+     *
+     * @param nbtIndex index of the current world's nbt
+     * @return packet handler
+     */
+    public PacketHandler worldDataTrackerHandler(int nbtIndex) {
         return wrapper -> {
             EntityTracker tracker = tracker(wrapper.user());
 
@@ -381,6 +388,12 @@ public abstract class EntityRewriter<T extends Protocol> extends RewriterBase<T>
             } else {
                 Via.getPlatform().getLogger().warning("Min Y missing in dimension data: " + registryData);
             }
+
+            String world = wrapper.get(Type.STRING, 0);
+            if (tracker.currentWorld() != null && !tracker.currentWorld().equals(world)) {
+                tracker.clearEntities();
+            }
+            tracker.setCurrentWorld(world);
         };
     }