Avoid refresh loop if no model data needs refreshing

Author: embeddedt

forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/model_data_manager_cme/ModelDataManagerMixin.java

@@ -6,13 +6,15 @@
 import net.minecraft.world.level.Level;
 import net.minecraftforge.client.model.ModelDataManager;
 import org.embeddedt.modernfix.annotation.ClientOnlyMixin;
+import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.ModifyArg;
 import org.spongepowered.asm.mixin.injection.Redirect;
 
 import java.util.Collections;
+import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Function;
@@ -27,6 +29,8 @@ public abstract class ModelDataManagerMixin {
         throw new AssertionError();
     }
 
+    @Shadow @Final private static Map<ChunkPos, Set<BlockPos>> needModelDataRefresh;
+
     /**
      * Make the set of positions to refresh a real concurrent hash set rather than relying on synchronizedSet,
      * because the returned iterator won't be thread-safe otherwise. See https://github.com/AppliedEnergistics/Applied-Energistics-2/issues/7511
@@ -40,7 +44,8 @@ private static Function<ChunkPos, Set<BlockPos>> changeTypeOfSetUsed(Function<Ch
     private static void onlyRefreshOnMainThread(Level toUpdate, ChunkPos pos) {
         // Only refresh model data on the main thread. This prevents calling getBlockEntity from worker threads
         // which could cause weird CMEs or other behavior.
-        if(Minecraft.getInstance().isSameThread()) {
+        // Avoid the loop if no model data needs to be refreshed, to prevent unnecessary allocation.
+        if(Minecraft.getInstance().isSameThread() && !needModelDataRefresh.isEmpty()) {
             // Refresh the given chunk, and all its neighbors. This is less efficient than the default code
             // but we have no choice since we need to not do refreshing on workers, and blocks might
             // try to access model data in neighboring chunks.