From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <spottedleaf@spottedleaf.dev>
Date: Mon, 27 Apr 2020 02:48:06 -0700
Subject: [PATCH] Reduce MutableInt allocations from light engine

We can abuse the fact light is single threaded and share an instance
per light engine instance

diff --git a/src/main/java/net/minecraft/server/LightEngineBlock.java b/src/main/java/net/minecraft/server/LightEngineBlock.java
index 29e12f76a3e424d36506144e09e083cc5ce3bedc..4db28b9a9b8a1e91911126172c6670c252dd49cb 100644
--- a/src/main/java/net/minecraft/server/LightEngineBlock.java
+++ b/src/main/java/net/minecraft/server/LightEngineBlock.java
@@ -6,6 +6,7 @@ public final class LightEngineBlock extends LightEngineLayer<LightEngineStorageB
 
     private static final EnumDirection[] e = EnumDirection.values();
     private final BlockPosition.MutableBlockPosition f = new BlockPosition.MutableBlockPosition();
+    private final MutableInt mutableint = new MutableInt(); // Paper
 
     public LightEngineBlock(ILightAccess ilightaccess) {
         super(ilightaccess, EnumSkyBlock.BLOCK, new LightEngineStorageBlock(ilightaccess));
@@ -37,7 +38,7 @@ public final class LightEngineBlock extends LightEngineLayer<LightEngineStorageB
             if (enumdirection == null) {
                 return 15;
             } else {
-                MutableInt mutableint = new MutableInt();
+                //MutableInt mutableint = new MutableInt(); // Paper - share mutableint, single threaded
                 IBlockData iblockdata = this.a(j, mutableint);
 
                 if (mutableint.getValue() >= 15) {
diff --git a/src/main/java/net/minecraft/server/LightEngineSky.java b/src/main/java/net/minecraft/server/LightEngineSky.java
index 2301a982e17ab9568e3da9ca84c4a024c7c1b214..f0b57784006752e031800a12a1a3c1a5945c636b 100644
--- a/src/main/java/net/minecraft/server/LightEngineSky.java
+++ b/src/main/java/net/minecraft/server/LightEngineSky.java
@@ -6,6 +6,7 @@ public final class LightEngineSky extends LightEngineLayer<LightEngineStorageSky
 
     private static final EnumDirection[] e = EnumDirection.values();
     private static final EnumDirection[] f = new EnumDirection[]{EnumDirection.NORTH, EnumDirection.SOUTH, EnumDirection.WEST, EnumDirection.EAST};
+    private final MutableInt mutableint = new MutableInt(); // Paper
 
     public LightEngineSky(ILightAccess ilightaccess) {
         super(ilightaccess, EnumSkyBlock.SKY, new LightEngineStorageSky(ilightaccess));
@@ -27,7 +28,7 @@ public final class LightEngineSky extends LightEngineLayer<LightEngineStorageSky
             if (k >= 15) {
                 return k;
             } else {
-                MutableInt mutableint = new MutableInt();
+                //MutableInt mutableint = new MutableInt(); // Paper - share mutableint, single threaded
                 IBlockData iblockdata = this.a(j, mutableint);
 
                 if (mutableint.getValue() >= 15) {