Add back datapack reload time tracking during world creation

Author: embeddedt

common/src/main/java/org/embeddedt/modernfix/common/mixin/feature/measure_time/WorldLoaderMixin.java

@@ -0,0 +1,35 @@
+package org.embeddedt.modernfix.common.mixin.feature.measure_time;
+
+import com.google.common.base.Stopwatch;
+import com.llamalad7.mixinextras.injector.ModifyReturnValue;
+import com.llamalad7.mixinextras.sugar.Share;
+import com.llamalad7.mixinextras.sugar.ref.LocalRef;
+import net.minecraft.server.WorldLoader;
+import org.embeddedt.modernfix.ModernFix;
+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.CallbackInfoReturnable;
+
+import java.util.concurrent.CompletableFuture;
+
+@Mixin(WorldLoader.class)
+public class WorldLoaderMixin {
+    @Inject(method = "load", at = @At("HEAD"))
+    private static void startStopwatch(CallbackInfoReturnable<CompletableFuture<?>> cir, @Share("stopwatch") LocalRef<Stopwatch> stopwatch) {
+        stopwatch.set(Stopwatch.createStarted());
+    }
+
+    @ModifyReturnValue(method = "load", at = @At("RETURN"))
+    private static CompletableFuture<?> finishStopwatch(CompletableFuture<?> original, @Share("stopwatch") LocalRef<Stopwatch> stopwatch) {
+        Stopwatch watch = stopwatch.get();
+        if (watch != null) {
+            return original.whenComplete((o, throwable) -> {
+                watch.stop();
+                ModernFix.LOGGER.warn("Initial datapack load took {}", watch);
+            });
+        } else {
+            return original;
+        }
+    }
+}