From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 7 May 2020 19:17:36 -0400
Subject: [PATCH] Fix Light Command

This lets you run /paper fixlight <chunkRadius> (max 5) to automatically
fix all light data in the chunks.

diff --git a/src/main/java/io/papermc/paper/command/PaperCommand.java b/src/main/java/io/papermc/paper/command/PaperCommand.java
index 395c43f6440c1e0e47919eef096ea8a8d552ccec..f44ab1d71210e84328661c0feb662989a5635b6d 100644
--- a/src/main/java/io/papermc/paper/command/PaperCommand.java
+++ b/src/main/java/io/papermc/paper/command/PaperCommand.java
@@ -2,6 +2,7 @@ package io.papermc.paper.command;
 
 import io.papermc.paper.command.subcommands.ChunkDebugCommand;
 import io.papermc.paper.command.subcommands.EntityCommand;
+import io.papermc.paper.command.subcommands.FixLightCommand;
 import io.papermc.paper.command.subcommands.HeapDumpCommand;
 import io.papermc.paper.command.subcommands.ReloadCommand;
 import io.papermc.paper.command.subcommands.VersionCommand;
@@ -42,6 +43,7 @@ public final class PaperCommand extends Command {
         commands.put(Set.of("reload"), new ReloadCommand());
         commands.put(Set.of("version"), new VersionCommand());
         commands.put(Set.of("debug", "chunkinfo"), new ChunkDebugCommand());
+        commands.put(Set.of("fixlight"), new FixLightCommand());
 
         return commands.entrySet().stream()
             .flatMap(entry -> entry.getKey().stream().map(s -> Map.entry(s, entry.getValue())))
diff --git a/src/main/java/io/papermc/paper/command/subcommands/FixLightCommand.java b/src/main/java/io/papermc/paper/command/subcommands/FixLightCommand.java
new file mode 100644
index 0000000000000000000000000000000000000000..190df802cb24aa360f6cf4d291e38b4b3fe4a2ac
--- /dev/null
+++ b/src/main/java/io/papermc/paper/command/subcommands/FixLightCommand.java
@@ -0,0 +1,121 @@
+package io.papermc.paper.command.subcommands;
+
+import io.papermc.paper.command.PaperSubcommand;
+import java.util.ArrayDeque;
+import java.util.Deque;
+import net.minecraft.server.MCUtil;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ChunkHolder;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.level.ThreadedLevelLightEngine;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.LevelChunk;
+import org.bukkit.command.CommandSender;
+import org.bukkit.craftbukkit.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+import static net.kyori.adventure.text.Component.text;
+import static net.kyori.adventure.text.format.NamedTextColor.GREEN;
+import static net.kyori.adventure.text.format.NamedTextColor.RED;
+
+@DefaultQualifier(NonNull.class)
+public final class FixLightCommand implements PaperSubcommand {
+    @Override
+    public boolean execute(final CommandSender sender, final String subCommand, final String[] args) {
+        this.doFixLight(sender, args);
+        return true;
+    }
+
+    private void doFixLight(final CommandSender sender, final String[] args) {
+        if (!(sender instanceof Player)) {
+            sender.sendMessage(text("Only players can use this command", RED));
+            return;
+        }
+        @Nullable Runnable post = null;
+        int radius = 2;
+        if (args.length > 0) {
+            try {
+                final int parsed = Integer.parseInt(args[0]);
+                if (parsed < 0) {
+                    sender.sendMessage(text("Radius cannot be negative!", RED));
+                    return;
+                }
+                final int maxRadius = 5;
+                radius = Math.min(maxRadius, parsed);
+                if (radius != parsed) {
+                    post = () -> sender.sendMessage(text("Radius '" + parsed + "' was not in the required range [0, " + maxRadius + "], it was lowered to the maximum (" + maxRadius + " chunks).", RED));
+                }
+            } catch (final Exception e) {
+                sender.sendMessage(text("'" + args[0] + "' is not a valid number.", RED));
+                return;
+            }
+        }
+
+        CraftPlayer player = (CraftPlayer) sender;
+        ServerPlayer handle = player.getHandle();
+        ServerLevel world = (ServerLevel) handle.level;
+        ThreadedLevelLightEngine lightengine = world.getChunkSource().getLightEngine();
+
+        net.minecraft.core.BlockPos center = MCUtil.toBlockPosition(player.getLocation());
+        Deque<ChunkPos> queue = new ArrayDeque<>(MCUtil.getSpiralOutChunks(center, radius));
+        updateLight(sender, world, lightengine, queue, post);
+    }
+
+    private void updateLight(
+        final CommandSender sender,
+        final ServerLevel world,
+        final ThreadedLevelLightEngine lightengine,
+        final Deque<ChunkPos> queue,
+        final @Nullable Runnable done
+    ) {
+        @Nullable ChunkPos coord = queue.poll();
+        if (coord == null) {
+            sender.sendMessage(text("All Chunks Light updated", GREEN));
+            if (done != null) {
+                done.run();
+            }
+            return;
+        }
+        world.getChunkSource().getChunkAtAsynchronously(coord.x, coord.z, false, false).whenCompleteAsync((either, ex) -> {
+            if (ex != null) {
+                sender.sendMessage(text("Error loading chunk " + coord, RED));
+                updateLight(sender, world, lightengine, queue, done);
+                return;
+            }
+            @Nullable LevelChunk chunk = (net.minecraft.world.level.chunk.LevelChunk) either.left().orElse(null);
+            if (chunk == null) {
+                updateLight(sender, world, lightengine, queue, done);
+                return;
+            }
+            lightengine.setTaskPerBatch(world.paperConfig().misc.lightQueueSize + 16 * 256); // ensure full chunk can fit into queue
+            sender.sendMessage(text("Updating Light " + coord));
+            int cx = chunk.getPos().x << 4;
+            int cz = chunk.getPos().z << 4;
+            for (int y = 0; y < world.getHeight(); y++) {
+                for (int x = 0; x < 16; x++) {
+                    for (int z = 0; z < 16; z++) {
+                        net.minecraft.core.BlockPos pos = new net.minecraft.core.BlockPos(cx + x, y, cz + z);
+                        lightengine.checkBlock(pos);
+                    }
+                }
+            }
+            lightengine.tryScheduleUpdate();
+            @Nullable ChunkHolder visibleChunk = world.getChunkSource().chunkMap.getVisibleChunkIfPresent(chunk.coordinateKey);
+            if (visibleChunk != null) {
+                world.getChunkSource().chunkMap.addLightTask(visibleChunk, () -> {
+                    MinecraftServer.getServer().processQueue.add(() -> {
+                        visibleChunk.broadcast(new net.minecraft.network.protocol.game.ClientboundLightUpdatePacket(chunk.getPos(), lightengine, null, null, true), false);
+                        updateLight(sender, world, lightengine, queue, done);
+                    });
+                });
+            } else {
+                updateLight(sender, world, lightengine, queue, done);
+            }
+            lightengine.setTaskPerBatch(world.paperConfig().misc.lightQueueSize);
+        }, MinecraftServer.getServer());
+    }
+}
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index eae2472f6dfd166cb457953ab396f85ca8c3f0f9..8ab5fd86e626958646935e460b603c875b8a841b 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -138,6 +138,12 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
     private final ChunkTaskPriorityQueueSorter queueSorter;
     private final ProcessorHandle<ChunkTaskPriorityQueueSorter.Message<Runnable>> worldgenMailbox;
     public final ProcessorHandle<ChunkTaskPriorityQueueSorter.Message<Runnable>> mainThreadMailbox;
+    // Paper start
+    final ProcessorHandle<ChunkTaskPriorityQueueSorter.Message<Runnable>> mailboxLight;
+    public void addLightTask(ChunkHolder playerchunk, Runnable run) {
+        this.mailboxLight.tell(ChunkTaskPriorityQueueSorter.message(playerchunk, run));
+    }
+    // Paper end
     public final ChunkProgressListener progressListener;
     private final ChunkStatusUpdateListener chunkStatusListener;
     public final ChunkMap.ChunkDistanceManager distanceManager;
@@ -261,11 +267,12 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
 
         this.progressListener = worldGenerationProgressListener;
         this.chunkStatusListener = chunkStatusChangeListener;
-        ProcessorMailbox<Runnable> threadedmailbox1 = ProcessorMailbox.create(executor, "light");
+        ProcessorMailbox<Runnable> lightthreaded; ProcessorMailbox<Runnable> threadedmailbox1 = lightthreaded = ProcessorMailbox.create(executor, "light"); // Paper
 
         this.queueSorter = new ChunkTaskPriorityQueueSorter(ImmutableList.of(threadedmailbox, mailbox, threadedmailbox1), executor, Integer.MAX_VALUE);
         this.worldgenMailbox = this.queueSorter.getProcessor(threadedmailbox, false);
         this.mainThreadMailbox = this.queueSorter.getProcessor(mailbox, false);
+        this.mailboxLight = this.queueSorter.getProcessor(lightthreaded, false);// Paper
         this.lightEngine = new ThreadedLevelLightEngine(chunkProvider, this, this.level.dimensionType().hasSkyLight(), threadedmailbox1, this.queueSorter.getProcessor(threadedmailbox1, false));
         this.distanceManager = new ChunkMap.ChunkDistanceManager(executor, mainThreadExecutor);
         this.overworldDataStorage = persistentStateManagerFactory;
