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/world/level/lighting/LightEngineBlock.java b/src/main/java/net/minecraft/world/level/lighting/LightEngineBlock.java
index 2a0a5a70c795ba33780c8db774eaf9769a85daa7..f6198069e3ca421b4f551939263c7cf8bd5b754e 100644
--- a/src/main/java/net/minecraft/world/level/lighting/LightEngineBlock.java
+++ b/src/main/java/net/minecraft/world/level/lighting/LightEngineBlock.java
@@ -16,6 +16,7 @@ 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));
@@ -47,7 +48,7 @@ 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/world/level/lighting/LightEngineSky.java b/src/main/java/net/minecraft/world/level/lighting/LightEngineSky.java
index 113c575a16121aa1146f21a6f41ebd9d12a0c924..37fa5faea6e2972e3eb8a3cbd1913ef38dc9456f 100644
--- a/src/main/java/net/minecraft/world/level/lighting/LightEngineSky.java
+++ b/src/main/java/net/minecraft/world/level/lighting/LightEngineSky.java
@@ -15,6 +15,7 @@ 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));
@@ -36,7 +37,7 @@ 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) {