Folia/patches/server/0019-Prevent-block-updates-in-non-loaded-or-non-owned-chu.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Mon, 17 Apr 2023 19:47:57 -0700
Subject: [PATCH] Prevent block updates in non-loaded or non-owned chunks

This is to prevent block physics from tripping thread checks by
far exceeding the bounds of the current region. While this does
add explicit block update suppression techniques, it's better
than the server crashing.

diff --git a/src/main/java/net/minecraft/world/level/Level.java b/src/main/java/net/minecraft/world/level/Level.java
index 32b9358bacabedf4513bb17c68200ef84a95a91b..afb3d0fa48b7fd6d273361c6dc32764b5d35c356 100644
--- a/src/main/java/net/minecraft/world/level/Level.java
+++ b/src/main/java/net/minecraft/world/level/Level.java
@@ -1248,7 +1248,8 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
     }
 
     public int getSignal(BlockPos pos, Direction direction) {
-        BlockState iblockdata = this.getBlockState(pos);
+        BlockState iblockdata = !io.papermc.paper.util.TickThread.isTickThreadFor((ServerLevel)this, pos) ? null : this.getBlockStateIfLoaded(pos); // Folia - block updates in unloaded chunks
+        if (iblockdata == null) return 0; // Folia - block updates in unloaded chunks
         int i = iblockdata.getSignal(this, pos, direction);
 
         return iblockdata.isRedstoneConductor(this, pos) ? Math.max(i, this.getDirectSignalTo(pos)) : i;
@@ -1418,7 +1419,7 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
             Direction enumdirection = (Direction) iterator.next();
             BlockPos blockposition1 = pos.relative(enumdirection);
 
-            if (this.hasChunkAt(blockposition1)) {
+            if (io.papermc.paper.util.TickThread.isTickThreadFor((ServerLevel)this, blockposition1) && this.hasChunkAt(blockposition1)) { // Folia - block updates in unloaded chunks
                 BlockState iblockdata = this.getBlockState(blockposition1);
 
                 if (iblockdata.is(Blocks.COMPARATOR)) {
diff --git a/src/main/java/net/minecraft/world/level/LevelReader.java b/src/main/java/net/minecraft/world/level/LevelReader.java
index 07802d0a25e49519c3c9b33c217e05002cf05e31..11b1a260f530ea7244856174b193eb6ef4d16849 100644
--- a/src/main/java/net/minecraft/world/level/LevelReader.java
+++ b/src/main/java/net/minecraft/world/level/LevelReader.java
@@ -124,7 +124,8 @@ public interface LevelReader extends BlockAndTintGetter, CollisionGetter, BiomeM
     }
 
     default int getDirectSignal(BlockPos pos, Direction direction) {
-        return this.getBlockState(pos).getDirectSignal(this, pos, direction);
+        BlockState blockstate = this instanceof net.minecraft.server.level.ServerLevel serverLevel && !io.papermc.paper.util.TickThread.isTickThreadFor(serverLevel, pos) ? null : this.getBlockStateIfLoaded(pos);  // Folia - block updates in unloaded chunks
+        return blockstate == null ? 0 : blockstate.getDirectSignal(this, pos, direction); // Folia - block updates in unloaded chunks
     }
 
     default ChunkAccess getChunk(BlockPos pos) {
diff --git a/src/main/java/net/minecraft/world/level/block/DetectorRailBlock.java b/src/main/java/net/minecraft/world/level/block/DetectorRailBlock.java
index 05dfb1790a292f9f85b641377c2ca3675726c127..971fcb61915f8b5f3fc4cbe3f3e4c8d639abdee6 100644
--- a/src/main/java/net/minecraft/world/level/block/DetectorRailBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/DetectorRailBlock.java
@@ -127,9 +127,9 @@ public class DetectorRailBlock extends BaseRailBlock {
 
         while (iterator.hasNext()) {
             BlockPos blockposition1 = (BlockPos) iterator.next();
-            BlockState iblockdata1 = world.getBlockState(blockposition1);
+            BlockState iblockdata1 = !io.papermc.paper.util.TickThread.isTickThreadFor((ServerLevel)world, blockposition1) ? null : world.getBlockStateIfLoaded(blockposition1); // Folia - block updates in unloaded chunks
 
-            world.neighborChanged(iblockdata1, blockposition1, iblockdata1.getBlock(), pos, false);
+            if (iblockdata1 != null) world.neighborChanged(iblockdata1, blockposition1, iblockdata1.getBlock(), pos, false); // Folia - block updates in unloaded chunks
         }
 
     }
diff --git a/src/main/java/net/minecraft/world/level/block/PoweredRailBlock.java b/src/main/java/net/minecraft/world/level/block/PoweredRailBlock.java
index 7fddb6fa8fd30ef88346a59f7867aae792f13772..b963f364b4763091c3b5d0f938eaa6798ffa4553 100644
--- a/src/main/java/net/minecraft/world/level/block/PoweredRailBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/PoweredRailBlock.java
@@ -97,9 +97,9 @@ public class PoweredRailBlock extends BaseRailBlock {
     }
 
     protected boolean isSameRailWithPower(Level world, BlockPos pos, boolean flag, int distance, RailShape shape) {
-        BlockState iblockdata = world.getBlockState(pos);
+        BlockState iblockdata = !io.papermc.paper.util.TickThread.isTickThreadFor((net.minecraft.server.level.ServerLevel)world, pos) ? null : world.getBlockStateIfLoaded(pos); // Folia - block updates in unloaded chunks
 
-        if (!iblockdata.is((Block) this)) {
+        if (iblockdata == null || !iblockdata.is((Block) this)) { // Folia - block updates in unloaded chunks
             return false;
         } else {
             RailShape blockpropertytrackposition1 = (RailShape) iblockdata.getValue(PoweredRailBlock.SHAPE);
diff --git a/src/main/java/net/minecraft/world/level/block/RedStoneWireBlock.java b/src/main/java/net/minecraft/world/level/block/RedStoneWireBlock.java
index cc019091a2decbc1e5c760129778b42ea1d449d6..068823de0f7adf7d9d6c90694e10401d704ecbad 100644
--- a/src/main/java/net/minecraft/world/level/block/RedStoneWireBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/RedStoneWireBlock.java
@@ -193,8 +193,9 @@ public class RedStoneWireBlock extends Block {
         while (iterator.hasNext()) {
             Direction enumdirection = (Direction) iterator.next();
             RedstoneSide blockpropertyredstoneside = (RedstoneSide) state.getValue((Property) RedStoneWireBlock.PROPERTY_BY_DIRECTION.get(enumdirection));
+            BlockState currState; blockposition_mutableblockposition.setWithOffset(pos, enumdirection); // Folia - block updates in unloaded chunks
 
-            if (blockpropertyredstoneside != RedstoneSide.NONE && !world.getBlockState(blockposition_mutableblockposition.setWithOffset(pos, enumdirection)).is((Block) this)) {
+            if (blockpropertyredstoneside != RedstoneSide.NONE && (currState = (world instanceof net.minecraft.server.level.ServerLevel serverLevel && !io.papermc.paper.util.TickThread.isTickThreadFor(serverLevel, pos) ? null : world.getBlockStateIfLoaded(blockposition_mutableblockposition))) != null && !currState.is((Block) this)) { // Folia - block updates in unloaded chunks
                 blockposition_mutableblockposition.move(Direction.DOWN);
                 BlockState iblockdata1 = world.getBlockState(blockposition_mutableblockposition);
 
diff --git a/src/main/java/net/minecraft/world/level/redstone/CollectingNeighborUpdater.java b/src/main/java/net/minecraft/world/level/redstone/CollectingNeighborUpdater.java
index 7c1768452fa0f7278ccc84470ef0965a3f96b0df..7b5de18daeba5945c82887768611353a5b003f7f 100644
--- a/src/main/java/net/minecraft/world/level/redstone/CollectingNeighborUpdater.java
+++ b/src/main/java/net/minecraft/world/level/redstone/CollectingNeighborUpdater.java
@@ -119,7 +119,8 @@ public class CollectingNeighborUpdater implements NeighborUpdater {
         @Override
         public boolean runNext(Level world) {
             BlockPos blockPos = this.sourcePos.relative(NeighborUpdater.UPDATE_ORDER[this.idx++]);
-            BlockState blockState = world.getBlockState(blockPos);
+            BlockState blockState = !io.papermc.paper.util.TickThread.isTickThreadFor((net.minecraft.server.level.ServerLevel)world, blockPos) ? null : world.getBlockStateIfLoaded(blockPos); // Folia - block updates in unloaded chunks
+            if (blockState != null) { // Folia - block updates in unloaded chunks
             // Paper start
             try {
                 boolean cancelled = false;
@@ -141,6 +142,7 @@ public class CollectingNeighborUpdater implements NeighborUpdater {
                 world.lastPhysicsProblem = new BlockPos(blockPos);
             }
             // Paper end
+            } // Folia - block updates in unloaded chunks
             if (this.idx < NeighborUpdater.UPDATE_ORDER.length && NeighborUpdater.UPDATE_ORDER[this.idx] == this.skipDirection) {
                 ++this.idx;
             }
@@ -156,7 +158,9 @@ public class CollectingNeighborUpdater implements NeighborUpdater {
     static record ShapeUpdate(Direction direction, BlockState state, BlockPos pos, BlockPos neighborPos, int updateFlags) implements CollectingNeighborUpdater.NeighborUpdates {
         @Override
         public boolean runNext(Level world) {
+            if (io.papermc.paper.util.TickThread.isTickThreadFor((net.minecraft.server.level.ServerLevel)world, this.pos) && world.getChunkIfLoaded(this.pos) != null) { // Folia - block updates in unloaded chunks
             NeighborUpdater.executeShapeUpdate(world, this.direction, this.state, this.pos, this.neighborPos, this.updateFlags, 512);
+            } // Folia - block updates in unloaded chunks
             return false;
         }
     }
@@ -164,8 +168,8 @@ public class CollectingNeighborUpdater implements NeighborUpdater {
     static record SimpleNeighborUpdate(BlockPos pos, Block block, BlockPos neighborPos) implements CollectingNeighborUpdater.NeighborUpdates {
         @Override
         public boolean runNext(Level world) {
-            BlockState blockState = world.getBlockState(this.pos);
-            NeighborUpdater.executeUpdate(world, blockState, this.pos, this.block, this.neighborPos, false);
+            BlockState blockState = !io.papermc.paper.util.TickThread.isTickThreadFor((net.minecraft.server.level.ServerLevel)world, this.pos) ? null : world.getBlockStateIfLoaded(this.pos); // Folia - block updates in unloaded chunks
+            if (blockState != null) NeighborUpdater.executeUpdate(world, blockState, this.pos, this.block, this.neighborPos, false); // Folia - block updates in unloaded chunks
             return false;
         }
     }