Paper/patches/server/0821-Fix-ChunkSnapshot-isSectionEmpty-int-and-optimize-Pa.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jason Penilla <11360596+jpenilla@users.noreply.github.com>
Date: Thu, 9 Dec 2021 00:08:11 -0800
Subject: [PATCH] Fix ChunkSnapshot#isSectionEmpty(int) and optimize
 PalettedContainer copying by not using codecs


diff --git a/src/main/java/org/bukkit/craftbukkit/CraftChunk.java b/src/main/java/org/bukkit/craftbukkit/CraftChunk.java
index ee6887111b591f174b9f871ce8680a30dc9e2725..f20293426b104ed0c02a931b5ab77f87590f0c18 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftChunk.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftChunk.java
@@ -280,14 +280,17 @@ public class CraftChunk implements Chunk {
         boolean[] sectionEmpty = new boolean[cs.length];
         PalettedContainer<Biome>[] biome = (includeBiome || includeBiomeTempRain) ? new PalettedContainer[cs.length] : null;
 
-        Registry<Biome> iregistry = this.worldServer.registryAccess().registryOrThrow(Registry.BIOME_REGISTRY);
-        Codec<PalettedContainer<Biome>> biomeCodec = PalettedContainer.codec(iregistry, iregistry.byNameCodec(), PalettedContainer.Strategy.SECTION_BIOMES, iregistry.getOrThrow(Biomes.PLAINS), null); // Paper - Anti-Xray - Add preset biomes
 
         for (int i = 0; i < cs.length; i++) {
-            CompoundTag data = new CompoundTag();
 
-            data.put("block_states", ChunkSerializer.BLOCK_STATE_CODEC.encodeStart(NbtOps.INSTANCE, cs[i].getStates()).get().left().get());
-            sectionBlockIDs[i] = ChunkSerializer.BLOCK_STATE_CODEC.parse(NbtOps.INSTANCE, data.getCompound("block_states")).get().left().get();
+            // Paper start
+            sectionEmpty[i] = cs[i].hasOnlyAir(); // Paper - fix sectionEmpty array not being filled
+            if (!sectionEmpty[i]) {
+                sectionBlockIDs[i] = cs[i].getStates().copy(); // Paper - use copy instead of round tripping with codecs
+            } else {
+                sectionBlockIDs[i] = CraftChunk.emptyBlockIDs; // Paper - use cached instance for empty block sections
+            }
+            // Paper end
 
             LevelLightEngine lightengine = chunk.level.getLightEngine();
             DataLayer skyLightArray = lightengine.getLayerListener(LightLayer.SKY).getDataLayerData(SectionPos.of(x, i, z));
@@ -306,8 +309,7 @@ public class CraftChunk implements Chunk {
             }
 
             if (biome != null) {
-                data.put("biomes", biomeCodec.encodeStart(NbtOps.INSTANCE, cs[i].getBiomes()).get().left().get());
-                biome[i] = biomeCodec.parse(NbtOps.INSTANCE, data.getCompound("biomes")).get().left().get();
+                biome[i] = cs[i].getBiomes().copy(); // Paper - use copy instead of round tripping with codecs
             }
         }