Slightly improve metadata iteration, remove redundant MetaHandlerEvent index

Lazily create the event if needed and share it with other filters when handling a metadata entry. Lastly, only add the additionally created meta once after the filter list, not once per filter.

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

@@ -110,9 +110,16 @@ public abstract class EntityRewriter<T extends Protocol> extends RewriterBase<T>
                 continue;
             }
 
+            MetaHandlerEvent event = null;
             for (MetaFilter filter : metadataFilters) {
-                if (filter.isFiltered(type, metadata)) {
-                    MetaHandlerEvent event = new MetaHandlerEventImpl(connection, type, entityId, metadata.id(), metadata, metadataList);
+                if (!filter.isFiltered(type, metadata)) {
+                    continue;
+                }
+                if (event == null) {
+                    // Only initialize when needed and share event instance
+                    event = new MetaHandlerEventImpl(connection, type, entityId, metadata, metadataList);
+                }
+
                 try {
                     filter.handler().handle(event, metadata);
                 } catch (Exception e) {
@@ -126,21 +133,18 @@ public abstract class EntityRewriter<T extends Protocol> extends RewriterBase<T>
                     metadataList.remove(i--);
                     break;
                 }
+            }
 
-                    Preconditions.checkArgument(event.index() == event.meta().id(), "Meta event id desync: Calls to meta().setId() are illegal");
-                    if (event.extraMeta() != null) {
-                        // Add newly created meta
+            if (event != null && event.extraMeta() != null) {
+                // Finally add newly created meta
                 metadataList.addAll(event.extraMeta());
-                        event.clearExtraMeta();
-                    }
-                }
             }
             i++;
         }
     }
 
     @Deprecated
-    private boolean callOldMetaHandler(int entityId, EntityType type, Metadata metadata, List<Metadata> metadataList, UserConnection connection) {
+    private boolean callOldMetaHandler(int entityId, @Nullable EntityType type, Metadata metadata, List<Metadata> metadataList, UserConnection connection) {
         try {
             handleMetadata(entityId, type, metadata, metadataList, connection);
             return true;
@@ -498,14 +502,14 @@ public abstract class EntityRewriter<T extends Protocol> extends RewriterBase<T>
      * Returns the entity tracker for the current protocol.
      *
      * @param connection user connection
-     * @param <T>        entity tracker type
+     * @param <E>        entity tracker type
      * @return entity tracker
      */
-    public <T extends EntityTracker> T tracker(UserConnection connection) {
+    public <E extends EntityTracker> E tracker(UserConnection connection) {
         return connection.getEntityTracker(protocol.getClass());
     }
 
-    private void logException(Exception e, EntityType type, List<Metadata> metadataList, Metadata metadata) {
+    private void logException(Exception e, @Nullable EntityType type, List<Metadata> metadataList, Metadata metadata) {
         if (!Via.getConfig().isSuppressMetadataErrors() || Via.getManager().isDebug()) {
             Logger logger = Via.getPlatform().getLogger();
             logger.warning("An error occurred with entity metadata handler");

common/src/main/java/com/viaversion/viaversion/rewriter/meta/MetaFilter.java

@@ -83,10 +83,12 @@ public class MetaFilter {
      * @param metadata metadata
      * @return whether the meta should be filtered
      */
-    public boolean isFiltered(EntityType type, Metadata metadata) {
+    public boolean isFiltered(@Nullable EntityType type, Metadata metadata) {
         // First check if the filter has no type or the type is equal or part of the filtered parent types
         // Applicable if no specific index is filtered or the indexes are equal
-        return (this.type == null || (filterFamily ? type.isOrHasParent(this.type) : this.type == type)) && (index == -1 || metadata.id() == index);
+        return (this.type == null
+                || type != null && (this.filterFamily ? type.isOrHasParent(this.type) : this.type == type))
+                && (this.index == -1 || metadata.id() == this.index);
     }
 
     @Override

common/src/main/java/com/viaversion/viaversion/rewriter/meta/MetaHandler.java

@@ -27,7 +27,7 @@ public interface MetaHandler {
      * Handles a metadata entry of an entity.
      *
      * @param event metadata event
-     * @param meta  metadata, convenience field for {@link MetaHandlerEvent#meta()}
+     * @param meta  metadata, convenience parameter for {@link MetaHandlerEvent#meta()}
      */
     void handle(MetaHandlerEvent event, Metadata meta);
 }

common/src/main/java/com/viaversion/viaversion/rewriter/meta/MetaHandlerEvent.java

@@ -41,25 +41,29 @@ public interface MetaHandlerEvent {
     int entityId();
 
     /**
-     * Returns the entity type of the entity the metadata belongs to.
+     * Returns the entity type of the entity the metadata belongs to if tracked.
      *
-     * @return entity type of the entity
+     * @return entity type of the entity if tracked, else null
      */
-    EntityType entityType();
+    @Nullable EntityType entityType();
 
     /**
      * Returns the metadata index.
      *
      * @return return meta index
      */
-    int index();
+    default int index() {
+        return meta().id();
+    }
 
     /**
      * Sets the metadata index.
      *
      * @param index new metadata index
      */
-    void setIndex(int index);
+    default void setIndex(int index) {
+        meta().setId(index);
+    }
 
     /**
      * Returns the metadata by the given index if present.
@@ -71,7 +75,6 @@ public interface MetaHandlerEvent {
 
     /**
      * Returns the metadata.
-     * Do NOT call {@link Metadata#setId(int)} and instead use {@link MetaHandlerEvent#setIndex(int)}.
      *
      * @return return metadata
      */
@@ -113,9 +116,4 @@ public interface MetaHandlerEvent {
      * @param metadata metadata
      */
     void createExtraMeta(Metadata metadata);
-
-    /**
-     * Clears the additional metadata.
-     */
-    void clearExtraMeta();
 }

common/src/main/java/com/viaversion/viaversion/rewriter/meta/MetaHandlerEventImpl.java

@@ -34,14 +34,12 @@ public class MetaHandlerEventImpl implements MetaHandlerEvent {
     private final List<Metadata> metadataList;
     private final Metadata meta;
     private List<Metadata> extraData;
-    private int index;
     private boolean cancel;
 
-    public MetaHandlerEventImpl(UserConnection connection, EntityType entityType, int entityId, int index, Metadata meta, List<Metadata> metadataList) {
+    public MetaHandlerEventImpl(UserConnection connection, @Nullable EntityType entityType, int entityId, Metadata meta, List<Metadata> metadataList) {
         this.connection = connection;
         this.entityType = entityType;
         this.entityId = entityId;
-        this.index = index;
         this.meta = meta;
         this.metadataList = metadataList;
     }
@@ -67,21 +65,10 @@ public class MetaHandlerEventImpl implements MetaHandlerEvent {
     }
 
     @Override
-    public EntityType entityType() {
+    public @Nullable EntityType entityType() {
         return entityType;
     }
 
-    @Override
-    public int index() {
-        return index;
-    }
-
-    @Override
-    public void setIndex(int index) {
-        this.index = index;
-        meta.setId(index);
-    }
-
     @Override
     public Metadata meta() {
         return meta;
@@ -111,9 +98,4 @@ public class MetaHandlerEventImpl implements MetaHandlerEvent {
     public void createExtraMeta(Metadata metadata) {
         (extraData != null ? extraData : (extraData = new ArrayList<>())).add(metadata);
     }
-
-    @Override
-    public void clearExtraMeta() {
-        extraData = null;
-    }
 }