Optimize MultiVariant.resolveParents

common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/model_optimizations/MultiVariantMixin.java

@@ -0,0 +1,41 @@
+package org.embeddedt.modernfix.common.mixin.perf.model_optimizations;
+
+import it.unimi.dsi.fastutil.objects.ObjectOpenHashSet;
+import net.minecraft.client.renderer.block.model.MultiVariant;
+import net.minecraft.client.renderer.block.model.Variant;
+import net.minecraft.client.resources.model.UnbakedModel;
+import net.minecraft.resources.ResourceLocation;
+import org.embeddedt.modernfix.annotation.ClientOnlyMixin;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Overwrite;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.util.List;
+import java.util.function.Function;
+
+@Mixin(value = MultiVariant.class, priority = 700)
+@ClientOnlyMixin
+public abstract class MultiVariantMixin {
+    @Shadow public abstract List<Variant> getVariants();
+
+    /**
+     * @author embeddedt
+     * @reason avoid streams, try to optimize for common case
+     */
+    @Overwrite
+    public void resolveParents(Function<ResourceLocation, UnbakedModel> modelGetter) {
+        var variants = this.getVariants();
+        // There is usually only a single variant
+        if (variants.size() == 1) {
+            modelGetter.apply(variants.get(0).getModelLocation()).resolveParents(modelGetter);
+        } else if(variants.size() > 1) {
+            ObjectOpenHashSet<ResourceLocation> seenLocations = new ObjectOpenHashSet<>(variants.size());
+            for (var variant : variants) {
+                var location = variant.getModelLocation();
+                if (seenLocations.add(location)) {
+                    modelGetter.apply(location).resolveParents(modelGetter);
+                }
+            }
+        }
+    }
+}