Paper/patches/server/0168-API-to-get-a-BlockState-without-a-snapshot.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 6 Nov 2017 21:08:22 -0500
Subject: [PATCH] API to get a BlockState without a snapshot

This allows you to get a BlockState without creating a snapshot, operating
on the real tile entity.

This is useful for where performance is needed

also Avoid NPE during CraftBlockEntityState load if could not get TE

If Tile Entity was null, correct Sign to return empty lines instead of null

diff --git a/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
index 1e416b23a38458f16add472cea09b0ac5ac91869..6f61fd8224fb4094f38a851300ab55f94523c252 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
@@ -45,6 +45,7 @@ public abstract class BlockEntity implements io.papermc.paper.util.KeyedObject {
         this.type = type;
         this.worldPosition = pos.immutable();
         this.blockState = state;
+        this.persistentDataContainer = new CraftPersistentDataContainer(DATA_TYPE_REGISTRY); // Paper - always init
     }
 
     public static BlockPos getPosFromTag(CompoundTag nbt) {
@@ -86,7 +87,7 @@ public abstract class BlockEntity implements io.papermc.paper.util.KeyedObject {
 
     // CraftBukkit start - read container
     public void load(CompoundTag nbt) {
-        this.persistentDataContainer = new CraftPersistentDataContainer(BlockEntity.DATA_TYPE_REGISTRY);
+        this.persistentDataContainer.clear(); // Paper - clear instead of init
 
         net.minecraft.nbt.Tag persistentDataTag = nbt.get("PublicBukkitValues");
         if (persistentDataTag instanceof CompoundTag) {
@@ -260,8 +261,15 @@ public abstract class BlockEntity implements io.papermc.paper.util.KeyedObject {
 
     // CraftBukkit start - add method
     public InventoryHolder getOwner() {
+        // Paper start
+        return getOwner(true);
+    }
+    public InventoryHolder getOwner(boolean useSnapshot) {
+        // Paper end
         if (this.level == null) return null;
-        org.bukkit.block.BlockState state = this.level.getWorld().getBlockAt(this.worldPosition.getX(), this.worldPosition.getY(), this.worldPosition.getZ()).getState();
+        org.bukkit.block.Block block = this.level.getWorld().getBlockAt(this.worldPosition.getX(), this.worldPosition.getY(), this.worldPosition.getZ());
+        if (block.getType() == org.bukkit.Material.AIR) return null;
+        org.bukkit.block.BlockState state = block.getState(useSnapshot); // Paper
         if (state instanceof InventoryHolder) return (InventoryHolder) state;
         return null;
     }
diff --git a/src/main/java/org/bukkit/craftbukkit/block/CraftBlock.java b/src/main/java/org/bukkit/craftbukkit/block/CraftBlock.java
index d8b9a8276204ad8a2f045af9fe94185dbf150bc6..3250559589eb4db7b3df828144cee81a19651842 100644
--- a/src/main/java/org/bukkit/craftbukkit/block/CraftBlock.java
+++ b/src/main/java/org/bukkit/craftbukkit/block/CraftBlock.java
@@ -317,7 +317,20 @@ public class CraftBlock implements Block {
 
     @Override
     public BlockState getState() {
+        // Paper start
+        return this.getState(true);
+    }
+
+    @Override
+    public BlockState getState(boolean useSnapshot) {
+        boolean prev = CraftBlockEntityState.DISABLE_SNAPSHOT;
+        CraftBlockEntityState.DISABLE_SNAPSHOT = !useSnapshot;
+        try {
         return CraftBlockStates.getBlockState(this);
+        } finally {
+            CraftBlockEntityState.DISABLE_SNAPSHOT = prev;
+        }
+        // Paper end
     }
 
     @Override
diff --git a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java
index 7629a51ec284cab0db7e9238027d6acfa4f3083c..27f38af1eb71dda5dd175dcabc7a467ed772757a 100644
--- a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java
+++ b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java
@@ -6,19 +6,30 @@ import org.bukkit.World;
 import org.bukkit.block.TileState;
 import org.bukkit.persistence.PersistentDataContainer;
 
-public class CraftBlockEntityState<T extends BlockEntity> extends CraftBlockState implements TileState {
+public abstract class CraftBlockEntityState<T extends BlockEntity> extends CraftBlockState implements TileState { // Paper - revert revert
 
     private final T tileEntity;
     private final T snapshot;
+    public final boolean snapshotDisabled; // Paper
+    public static boolean DISABLE_SNAPSHOT = false; // Paper
 
     public CraftBlockEntityState(World world, T tileEntity) {
         super(world, tileEntity.getBlockPos(), tileEntity.getBlockState());
 
         this.tileEntity = tileEntity;
 
+        // Paper start
+        this.snapshotDisabled = DISABLE_SNAPSHOT;
+        if (DISABLE_SNAPSHOT) {
+            this.snapshot = this.tileEntity;
+        } else {
+            this.snapshot = this.createSnapshot(tileEntity);
+        }
         // copy tile entity data:
-        this.snapshot = this.createSnapshot(tileEntity);
-        this.load(snapshot);
+        if (this.snapshot != null) {
+            this.load(this.snapshot);
+        }
+        // Paper end
     }
 
     public void refreshSnapshot() {
diff --git a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockStates.java b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockStates.java
index 51ea68c433c4d530f8404d3174c5a121ce808a96..9d0934656bbd27df4b47b816540d02cfbfc80636 100644
--- a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockStates.java
+++ b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockStates.java
@@ -105,12 +105,10 @@ public final class CraftBlockStates {
     private static final BlockStateFactory<?> DEFAULT_FACTORY = new BlockStateFactory<CraftBlockState>(CraftBlockState.class) {
         @Override
         public CraftBlockState createBlockState(World world, BlockPos blockPosition, net.minecraft.world.level.block.state.BlockState blockData, BlockEntity tileEntity) {
-            // SPIGOT-6754, SPIGOT-6817: Restore previous behaviour for tile entities with removed blocks (loot generation post-destroy)
-            if (tileEntity != null) {
-                // block with unhandled TileEntity:
-                return new CraftBlockEntityState<>(world, tileEntity);
-            }
-            Preconditions.checkState(tileEntity == null, "Unexpected BlockState for %s", CraftMagicNumbers.getMaterial(blockData.getBlock()));
+            // Paper start - revert revert
+            // When a block is being destroyed, the TileEntity may temporarily still exist while the block's type has already been set to AIR. We ignore the TileEntity in this case.
+            Preconditions.checkState(tileEntity == null || CraftMagicNumbers.getMaterial(blockData.getBlock()) == Material.AIR, "Unexpected BlockState for %s", CraftMagicNumbers.getMaterial(blockData.getBlock()));
+            // Paper end
             return new CraftBlockState(world, blockPosition, blockData);
         }
     };
diff --git a/src/main/java/org/bukkit/craftbukkit/persistence/CraftPersistentDataContainer.java b/src/main/java/org/bukkit/craftbukkit/persistence/CraftPersistentDataContainer.java
index e2cb421132471ceb3db236cffea88585fbe3593a..af37bf2b8ef1c06e541fb42d15afdd9833ba93a4 100644
--- a/src/main/java/org/bukkit/craftbukkit/persistence/CraftPersistentDataContainer.java
+++ b/src/main/java/org/bukkit/craftbukkit/persistence/CraftPersistentDataContainer.java
@@ -172,6 +172,12 @@ public final class CraftPersistentDataContainer implements PersistentDataContain
         return (Map<String, Object>) CraftNBTTagConfigSerializer.serialize(this.toTagCompound());
     }
 
+    // Paper start
+    public void clear() {
+        this.customDataTags.clear();
+    }
+    // Paper end
+
     @FunctionalInterface
     public interface Callback {
         void onValueChange();