Fast BiomeManager seed obfuscation

leaf-server/minecraft-patches/features/0280-Fast-BiomeManager-seed-obfuscation.patch

@@ -0,0 +1,31 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: HaHaWTH <102713261+HaHaWTH@users.noreply.github.com>
+Date: Tue, 9 Nov 2077 00:00:00 +0800
+Subject: [PATCH] Fast BiomeManager seed obfuscation
+
+Pretty tiny optimization, but better than nothing
+
+diff --git a/net/minecraft/world/level/biome/BiomeManager.java b/net/minecraft/world/level/biome/BiomeManager.java
+index 00122472991ba0c1a0ea77053aad71cdfa92a7bd..2d3cfa8659d882585b9e698ac8edf5c704623b95 100644
+--- a/net/minecraft/world/level/biome/BiomeManager.java
++++ b/net/minecraft/world/level/biome/BiomeManager.java
+@@ -34,9 +34,18 @@ public class BiomeManager {
+         // Leaf end - cache getBiome
+     }
+ 
++    // Leaf start - Replace SHA-256 with XXHash
++    private static final net.jpountz.xxhash.XXHash64 XXHASH = net.jpountz.xxhash.XXHashFactory.fastestInstance().hash64();
+     public static long obfuscateSeed(long seed) {
+-        return Hashing.sha256().hashLong(seed).asLong();
++        if (org.dreeam.leaf.config.modules.opt.FastBiomeManagerSeedObfuscation.enabled) {
++            java.nio.ByteBuffer buf = java.nio.ByteBuffer.allocate(8);
++            buf.putLong(0, seed);
++            return XXHASH.hash(buf, org.dreeam.leaf.config.modules.opt.FastBiomeManagerSeedObfuscation.seedObfuscationKey);
++        } else {
++            return Hashing.sha256().hashLong(seed).asLong();
++        }
+     }
++    // Leaf end - Replace SHA-256 with XXHash
+ 
+     public BiomeManager withDifferentSource(BiomeManager.NoiseBiomeSource newSource) {
+         return new BiomeManager(newSource, this.biomeZoomSeed);

leaf-server/src/main/java/org/dreeam/leaf/config/modules/opt/FastBiomeManagerSeedObfuscation.java

@@ -0,0 +1,34 @@
+package org.dreeam.leaf.config.modules.opt;
+
+import org.dreeam.leaf.config.ConfigModules;
+import org.dreeam.leaf.config.EnumConfigCategory;
+import org.dreeam.leaf.config.annotations.Experimental;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+public class FastBiomeManagerSeedObfuscation extends ConfigModules {
+
+    public String getBasePath() {
+        return EnumConfigCategory.PERF.getBaseKeyName() + ".fast-biome-manager-seed-obfuscation";
+    }
+
+    @Experimental
+    public static boolean enabled = false;
+    public static long seedObfuscationKey = ThreadLocalRandom.current().nextLong();
+
+    @Override
+    public void onLoaded() {
+        enabled = config.getBoolean(getBasePath() + ".enabled", enabled,
+            config.pickStringRegionBased(
+                """
+                    **EXPERMIENTAL FEATURE**
+                    Replace vanilla SHA-256 seed obfuscation in BiomeManager with XXHash.""",
+                """
+                    **实验性功能**
+                    将原版 BiomeManager 的 SHA-256 种子混淆换成 XXHash."""));
+        seedObfuscationKey = config.getLong(getBasePath() + ".seed-obfuscation-key", seedObfuscationKey,
+            config.pickStringRegionBased(
+                "Seed obfuscation key for XXHash.",
+                "XXHash 的混淆种子."));
+    }
+}