Fix Forge calling getResource on every loot table unnecessarily

src/main/java/org/embeddedt/modernfix/common/mixin/perf/faster_loot_loading/ForgeHooksMixin.java

@@ -0,0 +1,57 @@
+package org.embeddedt.modernfix.common.mixin.perf.faster_loot_loading;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.resources.ResourceManager;
+import net.minecraft.world.level.storage.loot.LootTable;
+import net.minecraftforge.common.ForgeHooks;
+import org.apache.commons.lang3.function.TriFunction;
+import org.apache.logging.log4j.Logger;
+import org.embeddedt.modernfix.annotation.FeatureLevel;
+import org.embeddedt.modernfix.annotation.RequiresFeatureLevel;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Overwrite;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.util.Optional;
+
+import static net.minecraftforge.common.ForgeHooks.loadLootTable;
+
+@Mixin(value = ForgeHooks.class, remap = false)
+@RequiresFeatureLevel(FeatureLevel.BETA)
+public class ForgeHooksMixin {
+    @Shadow
+    @Final
+    private static Logger LOGGER;
+
+    private static boolean mfix$isVanillaTable(JsonElement data) {
+        if (!(data instanceof JsonObject obj)) {
+            return false;
+        }
+        var vanillaMarker = obj.getAsJsonPrimitive("mfix$isVanillaTable");
+        if (vanillaMarker == null) {
+            return false;
+        }
+        return vanillaMarker.getAsBoolean();
+    }
+
+    /**
+     * @author embeddedt
+     * @reason avoid getResource() call per loot table by using injected marker
+     */
+    @Overwrite
+    public static TriFunction<ResourceLocation, JsonElement, ResourceManager, Optional<LootTable>> getLootTableDeserializer(Gson gson, String directory) {
+        return (location, data, resourceManager) -> {
+            try {
+                boolean custom = !mfix$isVanillaTable(data);
+                return Optional.ofNullable(loadLootTable(gson, location, data, custom));
+            } catch (Exception exception) {
+                LOGGER.error("Couldn't parse element {}:{}", directory, location, exception);
+                return Optional.empty();
+            }
+        };
+    }
+}

src/main/java/org/embeddedt/modernfix/common/mixin/perf/faster_loot_loading/LootDataManagerMixin.java

@@ -0,0 +1,41 @@
+package org.embeddedt.modernfix.common.mixin.perf.faster_loot_loading;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.llamalad7.mixinextras.sugar.Local;
+import net.minecraft.resources.FileToIdConverter;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.resources.ResourceManager;
+import net.minecraft.world.level.storage.loot.LootDataManager;
+import net.minecraft.world.level.storage.loot.LootDataType;
+import org.embeddedt.modernfix.annotation.FeatureLevel;
+import org.embeddedt.modernfix.annotation.RequiresFeatureLevel;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.Map;
+
+@Mixin(LootDataManager.class)
+@RequiresFeatureLevel(FeatureLevel.BETA)
+public class LootDataManagerMixin {
+    /**
+     * @author embeddedt
+     * @reason inject a marker for vanilla loot tables into the JSON so that we can retrieve it from the deserializer
+     */
+    @Inject(method = "lambda$scheduleElementParse$5", at = @At(value = "INVOKE", target = "Lnet/minecraft/server/packs/resources/SimpleJsonResourceReloadListener;scanDirectory(Lnet/minecraft/server/packs/resources/ResourceManager;Ljava/lang/String;Lcom/google/gson/Gson;Ljava/util/Map;)V", shift = At.Shift.AFTER))
+    private static void mfix$scanAndCapture(ResourceManager resourceManager, LootDataType lootDataType, Map map, CallbackInfo ci,
+                                            @Local(ordinal = 1) Map<ResourceLocation, JsonElement> lootTables) {
+        FileToIdConverter converter = FileToIdConverter.json(lootDataType.directory());
+        var lootTableResourceMap = converter.listMatchingResources(resourceManager);
+        for (var entry : lootTableResourceMap.entrySet()) {
+            if (lootTables.get(converter.fileToId(entry.getKey())) instanceof JsonObject obj) {
+                var resource = entry.getValue();
+                if (resource != null && !resource.isBuiltin()) {
+                    obj.addProperty("mfix$isVanillaTable", true);
+                }
+            }
+        }
+    }
+}