From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 4 Jul 2018 02:10:36 -0400
Subject: [PATCH] Store reference to current Chunk for Entity and Block
 Entities

This enables us a fast reference to the entities current chunk instead
of having to look it up by hashmap lookups.

diff --git a/src/main/java/net/minecraft/server/Chunk.java b/src/main/java/net/minecraft/server/Chunk.java
index b39ce329aa0b2e8da679a7b658f707f1da1f1a99..4d7dc714748a82470d00e787eeb3dc7ca08c656a 100644
--- a/src/main/java/net/minecraft/server/Chunk.java
+++ b/src/main/java/net/minecraft/server/Chunk.java
@@ -29,7 +29,7 @@ public class Chunk implements IChunkAccess {
     private final ChunkSection[] sections;
     private BiomeStorage d;
     private final Map<BlockPosition, NBTTagCompound> e;
-    public boolean loaded;
+    public boolean loaded; public boolean isLoaded() { return loaded; } // Paper - OBFHELPER
     public final World world;
     public final Map<HeightMap.Type, HeightMap> heightMap;
     private final ChunkConverter i;
@@ -55,11 +55,36 @@ public class Chunk implements IChunkAccess {
         this(world, chunkcoordintpair, biomestorage, ChunkConverter.a, TickListEmpty.b(), TickListEmpty.b(), 0L, (ChunkSection[]) null, (Consumer) null);
     }
 
+    // Paper start
+    private class TileEntityHashMap extends java.util.HashMap<BlockPosition, TileEntity> {
+        @Override
+        public TileEntity put(BlockPosition key, TileEntity value) {
+            TileEntity replaced = super.put(key, value);
+            if (replaced != null) {
+                replaced.setCurrentChunk(null);
+            }
+            if (value != null) {
+                value.setCurrentChunk(Chunk.this);
+            }
+            return replaced;
+        }
+
+        @Override
+        public TileEntity remove(Object key) {
+            TileEntity removed = super.remove(key);
+            if (removed != null) {
+                removed.setCurrentChunk(null);
+            }
+            return removed;
+        }
+    }
+    // Paper end
+
     public Chunk(World world, ChunkCoordIntPair chunkcoordintpair, BiomeStorage biomestorage, ChunkConverter chunkconverter, TickList<Block> ticklist, TickList<FluidType> ticklist1, long i, @Nullable ChunkSection[] achunksection, @Nullable Consumer<Chunk> consumer) {
         this.sections = new ChunkSection[16];
         this.e = Maps.newHashMap();
         this.heightMap = Maps.newEnumMap(HeightMap.Type.class);
-        this.tileEntities = Maps.newHashMap();
+        this.tileEntities = new TileEntityHashMap(); // Paper
         this.l = Maps.newHashMap();
         this.m = Maps.newHashMap();
         this.n = new ShortList[16];
@@ -462,6 +487,7 @@ public class Chunk implements IChunkAccess {
         }
 
         entity.inChunk = true;
+        entity.setCurrentChunk(this); // Paper
         entity.chunkX = this.loc.x;
         entity.chunkY = k;
         entity.chunkZ = this.loc.z;
@@ -474,6 +500,7 @@ public class Chunk implements IChunkAccess {
         ((HeightMap) this.heightMap.get(heightmap_type)).a(along);
     }
 
+    public void removeEntity(Entity entity) { this.b(entity); } // Paper - OBFHELPER
     public void b(Entity entity) {
         this.a(entity, entity.chunkY);
     }
@@ -487,7 +514,12 @@ public class Chunk implements IChunkAccess {
             i = this.entitySlices.length - 1;
         }
 
-        this.entitySlices[i].remove(entity);
+        // Paper start
+        if (entity.currentChunk != null && entity.currentChunk.get() == this) entity.setCurrentChunk(null);
+        if (!this.entitySlices[i].remove(entity)) {
+            return;
+        }
+        // Paper end
         this.entities.remove(entity); // Paper
     }
 
diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index 6c7816fdc1ef476969cb70c8ea697b60746d6ab4..0d8262b1d2722e716f95db4c9a8a132c54b613cf 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -134,7 +134,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     private static final DataWatcherObject<Boolean> aB = DataWatcher.a(Entity.class, DataWatcherRegistry.i);
     private static final DataWatcherObject<Boolean> aC = DataWatcher.a(Entity.class, DataWatcherRegistry.i);
     protected static final DataWatcherObject<EntityPose> POSE = DataWatcher.a(Entity.class, DataWatcherRegistry.s);
-    public boolean inChunk;
+    public boolean inChunk; public boolean isAddedToChunk() { return inChunk; } // Paper - OBFHELPER
     public int chunkX; public int getChunkX() { return chunkX; } // Paper - OBFHELPER
     public int chunkY; public int getChunkY() { return chunkY; } // Paper - OBFHELPER
     public int chunkZ; public int getChunkZ() { return chunkZ; } // Paper - OBFHELPER
@@ -178,7 +178,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     }
 
     public boolean isChunkLoaded() {
-        return world.isChunkLoaded((int) Math.floor(this.locX) >> 4, (int) Math.floor(this.locZ) >> 4);
+        return getCurrentChunk() != null;
     }
     // CraftBukkit end
 
@@ -1709,6 +1709,43 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     }
 
     // Paper start
+    java.lang.ref.WeakReference<Chunk> currentChunk = null;
+
+    public void setCurrentChunk(Chunk chunk) {
+        this.currentChunk = chunk != null ? new java.lang.ref.WeakReference<>(chunk) : null;
+    }
+    /**
+     * Returns the entities current registered chunk. If the entity is not added to a chunk yet, it will return null
+     */
+    public Chunk getCurrentChunk() {
+        final Chunk chunk = currentChunk != null ? currentChunk.get() : null;
+        if (chunk != null && chunk.isLoaded()) {
+            return chunk;
+        }
+
+        return !isAddedToChunk() ? null : ((ChunkProviderServer) world.chunkProvider).getChunkAtIfLoadedMainThreadNoCache(getChunkX(), getChunkZ());
+    }
+
+    /**
+     * Returns the chunk at the location, using the entities local cache if avail
+     * Will only return null if the location specified is not loaded
+     */
+    public Chunk getCurrentChunkAt(int x, int z) {
+        Chunk chunk = getCurrentChunk();
+        if (chunk != null && getChunkX() == chunk.getPos().x && getChunkZ() == chunk.getPos().z) {
+            return chunk;
+        }
+        return ((ChunkProviderServer) world.chunkProvider).getChunkAtIfLoadedMainThreadNoCache(getChunkX(), getChunkZ());
+    }
+    /**
+     * Returns the chunk at the entities current location, using the entities local cache if avail
+     * Ideally this is always the same as getCurrentChunk, but only becomes different in registration issues.
+     * Will only return null if the location specified is not loaded
+     */
+    public Chunk getChunkAtLocation() {
+        return getCurrentChunkAt((int)Math.floor(locX) >> 4, (int)Math.floor(locZ) >> 4);
+    }
+
     private MinecraftKey entityKey;
     private String entityKeyString;
 
diff --git a/src/main/java/net/minecraft/server/TileEntity.java b/src/main/java/net/minecraft/server/TileEntity.java
index 9071bb7ece6d38d85b4ea11e53671f3ec5210b28..820180ab3f7053c348caa80cc21f15dfa3d26afd 100644
--- a/src/main/java/net/minecraft/server/TileEntity.java
+++ b/src/main/java/net/minecraft/server/TileEntity.java
@@ -51,6 +51,15 @@ public abstract class TileEntity implements KeyedObject { // Paper
         getMinecraftKey(); // Try to load if it doesn't exists.
         return tileEntityKeyString;
     }
+
+    private java.lang.ref.WeakReference<Chunk> currentChunk = null;
+    public Chunk getCurrentChunk() {
+        final Chunk chunk = currentChunk != null ? currentChunk.get() : null;
+        return chunk != null && chunk.isLoaded() ? chunk : null;
+    }
+    public void setCurrentChunk(Chunk chunk) {
+        this.currentChunk = chunk != null ? new java.lang.ref.WeakReference<>(chunk) : null;
+    }
     // Paper end
 
     @Nullable
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
index 056525526e87fa75f026278a82311640a3b466db..5a047dd68223363ef83f8d5b77adbd45f7531113 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -138,6 +138,7 @@ import net.minecraft.server.EntityZombieVillager;
 import net.minecraft.server.EnumChatFormat;
 import net.minecraft.server.IChatBaseComponent;
 import net.minecraft.server.NBTTagCompound;
+import org.bukkit.Chunk; // Paper
 import org.bukkit.EntityEffect;
 import org.bukkit.Location;
 import org.bukkit.Server;
@@ -179,6 +180,12 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
         this.entity = entity;
     }
 
+    @Override
+    public Chunk getChunk() {
+        net.minecraft.server.Chunk currentChunk = entity.getCurrentChunk();
+        return currentChunk != null ? currentChunk.bukkitChunk : getLocation().getChunk();
+    }
+
     public static CraftEntity getEntity(CraftServer server, Entity entity) {
         /*
          * Order is *EXTREMELY* important -- keep it right! =D
