Add basic preloading (#1221)

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/FaweBukkit.java

@@ -58,6 +58,7 @@ public class FaweBukkit implements IFawe, Listener {
     private boolean listeningImages;
     private final boolean chunksStretched;
     private final FAWEPlatformAdapterImpl platformAdapter;
+    private Preloader preloader;
 
     public FaweBukkit(Plugin plugin) {
         this.plugin = plugin;
@@ -277,9 +278,12 @@ public class FaweBukkit implements IFawe, Listener {
     }
 
     @Override
-    public Preloader getPreloader() {
+    public Preloader getPreloader(boolean initialise) {
         if (PaperLib.isPaper()) {
-            return new AsyncPreloader();
+            if (preloader == null && initialise) {
+                return preloader = new AsyncPreloader();
+            }
+            return preloader;
         }
         return null;
     }

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/regions/plotsquared/FaweDelegateRegionManager.java

@@ -264,7 +264,7 @@ public class FaweDelegateRegionManager {
                         .autoQueue(false)
                         .build();
                 FlatRegionFunction replace = new BiomeReplace(editSession, biome);
-                FlatRegionVisitor visitor = new FlatRegionVisitor(region, replace);
+                FlatRegionVisitor visitor = new FlatRegionVisitor(region, replace, editSession);
                 try {
                     Operations.completeLegacy(visitor);
                     editSession.flushQueue();

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitWorld.java

@@ -353,7 +353,7 @@ public class BukkitWorld extends AbstractWorld {
         int Z = pt.getBlockZ() >> 4;
         if (Fawe.isMainThread()) {
             world.getChunkAt(X, Z);
-        } else {
+        } else if (PaperLib.isPaper()) {
             PaperLib.getChunkAtAsync(world, X, Z, true);
         }
         //FAWE end

worldedit-core/src/main/java/com/fastasyncworldedit/core/Fawe.java

@@ -163,6 +163,9 @@ public class Fawe {
     }
 
     public void onDisable() {
+        if (imp().getPreloader(false) != null) {
+            imp().getPreloader(false).cancel();
+        }
     }
 
     public QueueHandler getQueueHandler() {

worldedit-core/src/main/java/com/fastasyncworldedit/core/IFawe.java

@@ -35,7 +35,13 @@ public interface IFawe {
 
     QueueHandler getQueueHandler();
 
-    Preloader getPreloader();
+    /**
+     * Get the preloader instance and initialise if needed
+     *
+     * @param initialise if the preloader should be initialised if null
+     * @return preloader instance
+     */
+    Preloader getPreloader(boolean initialise);
 
     default boolean isChunksStretched() {
         return true;

worldedit-core/src/main/java/com/fastasyncworldedit/core/configuration/Settings.java

@@ -319,9 +319,12 @@ public class Settings extends Config {
                 "Loading the right amount of chunks beforehand can speed up operations",
                 " - Low values may result in FAWE waiting on requests to the main thread",
                 " - Higher values use more memory and isn't noticeably faster",
+                " - A good (relatively) safe way to set this is",
+                " - Use 32 x GB of RAM / number of players expected to be using WE at the same time"
         })
-        //TODO Find out where this was used and why the usage was removed
+        // Renamed from PRELOAD_CHUNK because it was set to 100000... something that lots of servers will now have which is
-        public int PRELOAD_CHUNKS = 100000;
+        // wayyy too much...
+        public int PRELOAD_CHUNK_COUNT = 128;
 
         @Comment({
                 "If pooling is enabled (reduces GC, higher memory usage)",

worldedit-core/src/main/java/com/fastasyncworldedit/core/extension/platform/binding/ConsumeBindings.java

@@ -6,6 +6,7 @@ import com.fastasyncworldedit.core.util.MainUtil;
 import com.fastasyncworldedit.core.util.image.ImageUtil;
 import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.command.util.annotation.Confirm;
+import com.sk89q.worldedit.command.util.annotation.Preload;
 import com.sk89q.worldedit.command.util.annotation.Time;
 import com.sk89q.worldedit.entity.Entity;
 import com.sk89q.worldedit.extension.input.InputParseException;
@@ -98,6 +99,17 @@ public class ConsumeBindings extends Bindings {
         return radius;
     }
 
+    @Binding
+    @Preload(Preload.PreloadCheck.PRELOAD)
+    public void checkPreload(Actor actor, InjectedValueAccess context) {
+        Preload.PreloadCheck.PRELOAD.preload(actor, context);
+    }
+
+    @Binding
+    @Preload(Preload.PreloadCheck.NEVER)
+    public void neverPreload(Actor actor, InjectedValueAccess context) {
+    }
+
     @Binding
     public UUID playerUUID(Actor actor, String argument) {
         if (argument.equals("me")) {

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/SingleThreadQueueExtent.java

@@ -2,6 +2,7 @@ package com.fastasyncworldedit.core.queue.implementation;
 
 import com.fastasyncworldedit.core.Fawe;
 import com.fastasyncworldedit.core.configuration.Settings;
+import com.fastasyncworldedit.core.extent.PassthroughExtent;
 import com.fastasyncworldedit.core.extent.filter.block.CharFilterBlock;
 import com.fastasyncworldedit.core.extent.filter.block.ChunkFilterBlock;
 import com.fastasyncworldedit.core.extent.processor.EmptyBatchProcessor;
@@ -19,9 +20,15 @@ import com.fastasyncworldedit.core.queue.implementation.chunk.ChunkHolder;
 import com.fastasyncworldedit.core.queue.implementation.chunk.NullChunk;
 import com.fastasyncworldedit.core.util.MathMan;
 import com.fastasyncworldedit.core.util.MemUtil;
+import com.fastasyncworldedit.core.wrappers.WorldWrapper;
 import com.google.common.util.concurrent.Futures;
+import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.math.BlockVector2;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.world.World;
 import it.unimi.dsi.fastutil.longs.Long2ObjectLinkedOpenHashMap;
 import org.apache.logging.log4j.Logger;
 
@@ -61,6 +68,8 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
 
     private final ReentrantLock getChunkLock = new ReentrantLock();
 
+    private World world = null;
+
     /**
      * Safety check to ensure that the thread being used matches the one being initialized on. - Can
      * be removed later
@@ -124,6 +133,7 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         this.initialized = false;
         this.setProcessor(EmptyBatchProcessor.getInstance());
         this.setPostProcessor(EmptyBatchProcessor.getInstance());
+        this.world = null;
     }
 
     /**
@@ -146,6 +156,14 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         this.setProcessor(EmptyBatchProcessor.getInstance());
         this.setPostProcessor(EmptyBatchProcessor.getInstance());
         initialized = true;
+
+        if (extent.isWorld()) {
+            world = (World) ((extent instanceof PassthroughExtent) ? ((PassthroughExtent) extent).getExtent() : extent);
+        } else if (extent instanceof EditSession) {
+            world = ((EditSession) extent).getWorld();
+        } else {
+            world = WorldWrapper.unwrap(extent);
+        }
     }
 
     @Override
@@ -289,6 +307,37 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         }
     }
 
+    /**
+     * Load a chunk in the world associated with this {@link SingleThreadQueueExtent} instance
+     *
+     * @param cx chunk X coordinate
+     * @param cz chunk Z coordinate
+     */
+    public void addChunkLoad(int cx, int cz) {
+        if (world == null) {
+            return;
+        }
+        world.checkLoadedChunk(BlockVector3.at(cx << 4, 0, cz << 4));
+    }
+
+    /**
+     * Define a region to be "preloaded" to the number of chunks provided by {@link Settings.QUEUE#PRELOAD_CHUNK_COUNT}
+     *
+     * @param region region of chunks
+     */
+    public void preload(Region region) {
+        if (Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT > 1) {
+            int loadCount = 0;
+            for (BlockVector2 from : region.getChunks()) {
+                if (loadCount >= Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT) {
+                    break;
+                }
+                loadCount++;
+                addChunkLoad(from.getBlockX(), from.getBlockZ());
+            }
+        }
+    }
+
     @Override
     public ChunkHolder create(boolean isFull) {
         return ChunkHolder.newInstance();

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/preloader/AsyncPreloader.java

@@ -2,41 +2,50 @@ package com.fastasyncworldedit.core.queue.implementation.preloader;
 
 import com.fastasyncworldedit.core.Fawe;
 import com.fastasyncworldedit.core.util.FaweTimer;
+import com.fastasyncworldedit.core.util.TaskManager;
 import com.fastasyncworldedit.core.util.collection.MutablePair;
 import com.sk89q.worldedit.IncompleteRegionException;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.WorldEdit;
-import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
-import com.sk89q.worldedit.regions.CuboidRegion;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.world.World;
 
+import javax.annotation.Nonnull;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
-
+import java.util.concurrent.atomic.AtomicBoolean;
 
 public class AsyncPreloader implements Preloader, Runnable {
 
     private final ConcurrentHashMap<UUID, MutablePair<World, Set<BlockVector2>>> update;
+    private final AtomicBoolean cancelled = new AtomicBoolean(false);
 
     public AsyncPreloader() {
         this.update = new ConcurrentHashMap<>();
-        Fawe.get().getQueueHandler().async(this);
+        TaskManager.IMP.laterAsync(this, 1);
     }
 
     @Override
-    public void cancel(Player player) {
+    public void cancel() {
-        cancelAndGet(player);
+        cancelled.set(true);
+        synchronized (update) {
+            update.clear();
+        }
     }
 
-    private MutablePair<World, Set<BlockVector2>> cancelAndGet(Actor player) {
+    @Override
-        MutablePair<World, Set<BlockVector2>> existing = update.get(player.getUniqueId());
+    public void cancel(@Nonnull Actor actor) {
+        cancelAndGet(actor);
+    }
+
+    private MutablePair<World, Set<BlockVector2>> cancelAndGet(@Nonnull Actor actor) {
+        MutablePair<World, Set<BlockVector2>> existing = update.get(actor.getUniqueId());
         if (existing != null) {
             existing.setValue(null);
         }
@@ -44,26 +53,22 @@ public class AsyncPreloader implements Preloader, Runnable {
     }
 
     @Override
-    public void update(Player player) {
+    public void update(@Nonnull Actor actor, @Nonnull World world) {
-        LocalSession session = WorldEdit.getInstance().getSessionManager().getIfPresent(player);
+        LocalSession session = WorldEdit.getInstance().getSessionManager().getIfPresent(actor);
         if (session == null) {
             return;
         }
-        World world = player.getWorld();
+        MutablePair<World, Set<BlockVector2>> existing = cancelAndGet(actor);
-        MutablePair<World, Set<BlockVector2>> existing = cancelAndGet(player);
         try {
             Region region = session.getSelection(world);
-            if (!(region instanceof CuboidRegion) || region.getVolume() > 50466816) {
+            if (region == null) {
-                // TOO LARGE or NOT CUBOID
                 return;
             }
             if (existing == null) {
-                MutablePair<World, Set<BlockVector2>> previous = update.putIfAbsent(
+                update.put(
-                        player.getUniqueId(),
+                        actor.getUniqueId(),
                         existing = new MutablePair<>()
                 );
-                if (previous != null) {
-                    existing = previous;
             }
             synchronized (existing) { // Ensure key & value are mutated together
                 existing.setKey(world);
@@ -72,7 +77,6 @@ public class AsyncPreloader implements Preloader, Runnable {
             synchronized (update) {
                 update.notify();
             }
-            }
         } catch (IncompleteRegionException ignored) {
         }
     }
@@ -80,11 +84,18 @@ public class AsyncPreloader implements Preloader, Runnable {
     @Override
     public void run() {
         FaweTimer timer = Fawe.get().getTimer();
-        try {
+        if (cancelled.get()) {
-            while (true) {
+            return;
-                if (!update.isEmpty()) {
+        }
-                    if (timer.getTPS() > 19) {
+        if (update.isEmpty()) {
+            TaskManager.IMP.laterAsync(this, 1);
+            return;
+        }
         Iterator<Map.Entry<UUID, MutablePair<World, Set<BlockVector2>>>> plrIter = update.entrySet().iterator();
+        while (timer.getTPS() > 18 && plrIter.hasNext()) {
+            if (cancelled.get()) {
+                return;
+            }
             Map.Entry<UUID, MutablePair<World, Set<BlockVector2>>> entry = plrIter.next();
             MutablePair<World, Set<BlockVector2>> pair = entry.getValue();
             World world = pair.getKey();
@@ -97,21 +108,14 @@ public class AsyncPreloader implements Preloader, Runnable {
                 }
             }
             plrIter.remove();
-                    } else {
-                        Thread.sleep(1000);
         }
-                } else {
+        if (cancelled.get()) {
-                    synchronized (update) {
+            return;
-                        update.wait();
-                    }
-                }
-            }
-        } catch (InterruptedException e) {
-            e.printStackTrace();
         }
+        TaskManager.IMP.laterAsync(this, 20);
     }
 
-    public void queueLoad(World world, BlockVector2 chunk) {
+    private void queueLoad(World world, BlockVector2 chunk) {
         world.checkLoadedChunk(BlockVector3.at(chunk.getX() << 4, 0, chunk.getZ() << 4));
     }
 

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/preloader/Preloader.java

@@ -1,11 +1,30 @@
 package com.fastasyncworldedit.core.queue.implementation.preloader;
 
-import com.sk89q.worldedit.entity.Player;
+import com.sk89q.worldedit.extension.platform.Actor;
+import com.sk89q.worldedit.world.World;
+
+import javax.annotation.Nonnull;
 
 public interface Preloader {
 
-    void cancel(Player player);
+    /**
+     * Tell the preloader to stop attempting to preload chunks
+     */
+    void cancel();
 
-    void update(Player player);
+    /**
+     * Cancel any preloading related to the given Actor
+     *
+     * @param actor Actor to cancel preloading of
+     */
+    void cancel(@Nonnull Actor actor);
+
+    /**
+     * Update the preloading for the given player, in the given world. Uses the player's current selection.
+     *
+     * @param actor Actor to update
+     * @param world World to use
+     */
+    void update(@Nonnull Actor actor, @Nonnull World world);
 
 }

worldedit-core/src/main/java/com/sk89q/worldedit/EditSession.java

@@ -1408,11 +1408,13 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
 
         // Pick how we're going to visit blocks
         RecursiveVisitor visitor;
+        //FAWE start - provide extent for preloading
         if (recursive) {
-            visitor = new RecursiveVisitor(mask, replace, (int) (radius * 2 + 1));
+            visitor = new RecursiveVisitor(mask, replace, (int) (radius * 2 + 1), this);
         } else {
-            visitor = new DownwardVisitor(mask, replace, origin.getBlockY(), (int) (radius * 2 + 1));
+            visitor = new DownwardVisitor(mask, replace, origin.getBlockY(), (int) (radius * 2 + 1), this);
         }
+        //FAWE end
 
         // Start at the origin
         visitor.visit(origin);
@@ -1667,7 +1669,7 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
         int minY = region.getMinimumPoint().getBlockY();
         int maxY = Math.min(getMaximumPoint().getBlockY(), region.getMaximumPoint().getBlockY() + 1);
         SurfaceRegionFunction surface = new SurfaceRegionFunction(this, offset, minY, maxY);
-        FlatRegionVisitor visitor = new FlatRegionVisitor(asFlatRegion(region), surface);
+        FlatRegionVisitor visitor = new FlatRegionVisitor(asFlatRegion(region), surface, this);
         //FAWE end
         Operations.completeBlindly(visitor);
         return this.changes = visitor.getAffected();
@@ -1686,7 +1688,9 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
 
         Naturalizer naturalizer = new Naturalizer(this);
         FlatRegion flatRegion = Regions.asFlatRegion(region);
-        LayerVisitor visitor = new LayerVisitor(flatRegion, minimumBlockY(region), maximumBlockY(region), naturalizer);
+        //FAWE start - provide extent for preloading
+        LayerVisitor visitor = new LayerVisitor(flatRegion, minimumBlockY(region), maximumBlockY(region), naturalizer, this);
+        //FAWE end
         Operations.completeBlindly(visitor);
         return this.changes = naturalizer.getAffected();
     }
@@ -1937,7 +1941,9 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
         } else {
             replace = new BlockReplace(this, BlockTypes.AIR.getDefaultState());
         }
-        RecursiveVisitor visitor = new RecursiveVisitor(mask, replace, (int) (radius * 2 + 1));
+        //FAWE start - provide extent for preloading
+        RecursiveVisitor visitor = new RecursiveVisitor(mask, replace, (int) (radius * 2 + 1), this);
+        //FAWE end
 
         // Around the origin in a 3x3 block
         for (BlockVector3 position : CuboidRegion.fromCenter(origin, 1)) {
@@ -1980,7 +1986,9 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
         );
 
         BlockReplace replace = new BlockReplace(this, fluid.getDefaultState());
-        NonRisingVisitor visitor = new NonRisingVisitor(mask, replace);
+        //FAWE start - provide extent for preloading
+        NonRisingVisitor visitor = new NonRisingVisitor(mask, replace, Integer.MAX_VALUE, this);
+        //FAWE end
 
         // Around the origin in a 3x3 block
         for (BlockVector3 position : CuboidRegion.fromCenter(origin, 1)) {
@@ -2586,7 +2594,9 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
         checkNotNull(region);
 
         SnowSimulator snowSimulator = new SnowSimulator(this, stack);
-        LayerVisitor layerVisitor = new LayerVisitor(region, region.getMinimumY(), region.getMaximumY(), snowSimulator);
+        //FAWE start - provide extent for preloading
+        LayerVisitor layerVisitor = new LayerVisitor(region, region.getMinimumY(), region.getMaximumY(), snowSimulator, this);
+        //FAWE end
         Operations.completeLegacy(layerVisitor);
         return snowSimulator.getAffected();
     }
@@ -2698,7 +2708,7 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
         );
 
         GroundFunction ground = new GroundFunction(new ExistingBlockMask(this), generator);
-        LayerVisitor visitor = new LayerVisitor(region, minimumBlockY(region), maximumBlockY(region), ground);
+        LayerVisitor visitor = new LayerVisitor(region, minimumBlockY(region), maximumBlockY(region), ground, this);
         visitor.setMask(new NoiseFilter2D(new RandomNoise(), density));
         Operations.completeLegacy(visitor);
         return this.changes = ground.getAffected();
@@ -2732,7 +2742,9 @@ public class EditSession extends PassthroughExtent implements AutoCloseable {
     public int makeForest(Region region, double density, TreeGenerator.TreeType treeType) throws MaxChangedBlocksException {
         ForestGenerator generator = new ForestGenerator(this, treeType);
         GroundFunction ground = new GroundFunction(new ExistingBlockMask(this), generator);
-        LayerVisitor visitor = new LayerVisitor(asFlatRegion(region), minimumBlockY(region), maximumBlockY(region), ground);
+        //FAWE start - provide extent for preloading
+        LayerVisitor visitor = new LayerVisitor(asFlatRegion(region), minimumBlockY(region), maximumBlockY(region), ground, this);
+        //FAWE end
         visitor.setMask(new NoiseFilter2D(new RandomNoise(), density));
         Operations.completeLegacy(visitor);
         return ground.getAffected();

worldedit-core/src/main/java/com/sk89q/worldedit/command/BiomeCommands.java

@@ -28,6 +28,8 @@ import com.sk89q.worldedit.command.util.CommandPermissions;
 import com.sk89q.worldedit.command.util.CommandPermissionsConditionGenerator;
 import com.sk89q.worldedit.command.util.Logging;
 import com.sk89q.worldedit.command.util.WorldEditAsyncCommandBuilder;
+import com.sk89q.worldedit.command.util.annotation.Confirm;
+import com.sk89q.worldedit.command.util.annotation.Preload;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.extension.platform.Capability;
@@ -162,6 +164,8 @@ public class BiomeCommands {
             descFooter = "By default, uses all the blocks in your selection"
     )
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
+    @Confirm(Confirm.Processor.REGION)
     @CommandPermissions("worldedit.biome.set")
     public void setBiome(
             Player player, LocalSession session, EditSession editSession,
@@ -184,9 +188,7 @@ public class BiomeCommands {
         if (mask != null) {
             replace = new RegionMaskingFilter(editSession, mask, replace);
         }
-        //FAWE start > add extent to RegionVisitor to allow chunk preloading
+        RegionVisitor visitor = new RegionVisitor(region, replace);
-        RegionVisitor visitor = new RegionVisitor(region, replace, editSession);
-        //FAWE end
         Operations.completeLegacy(visitor);
 
         player.print(Caption.of(

worldedit-core/src/main/java/com/sk89q/worldedit/command/ClipboardCommands.java

@@ -45,6 +45,7 @@ import com.sk89q.worldedit.command.util.CommandPermissions;
 import com.sk89q.worldedit.command.util.CommandPermissionsConditionGenerator;
 import com.sk89q.worldedit.command.util.Logging;
 import com.sk89q.worldedit.command.util.annotation.Confirm;
+import com.sk89q.worldedit.command.util.annotation.Preload;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.extent.clipboard.BlockArrayClipboard;
@@ -112,6 +113,7 @@ public class ClipboardCommands {
             desc = "Copy the selection to the clipboard"
     )
     @CommandPermissions("worldedit.clipboard.copy")
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public void copy(
             Actor actor, LocalSession session, EditSession editSession,
@@ -242,6 +244,7 @@ public class ClipboardCommands {
     )
     @CommandPermissions("worldedit.clipboard.cut")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public void cut(
             Actor actor, LocalSession session, EditSession editSession,

worldedit-core/src/main/java/com/sk89q/worldedit/command/GenerationCommands.java

@@ -33,6 +33,7 @@ import com.sk89q.worldedit.command.util.CommandPermissions;
 import com.sk89q.worldedit.command.util.CommandPermissionsConditionGenerator;
 import com.sk89q.worldedit.command.util.Logging;
 import com.sk89q.worldedit.command.util.annotation.Confirm;
+import com.sk89q.worldedit.command.util.annotation.Preload;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.function.mask.AbstractExtentMask;
@@ -435,6 +436,7 @@ public class GenerationCommands {
     )
     @CommandPermissions("worldedit.generation.shape.biome")
     @Logging(ALL)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int generateBiome(
             Actor actor, LocalSession session, EditSession editSession,
@@ -511,6 +513,7 @@ public class GenerationCommands {
     )
     @CommandPermissions("worldedit.generation.caves")
     @Logging(PLACEMENT)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public void caves(
             Actor actor, LocalSession session, EditSession editSession, @Selection Region region,
@@ -548,6 +551,7 @@ public class GenerationCommands {
     )
     @CommandPermissions("worldedit.generation.ore")
     @Logging(PLACEMENT)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public void ores(
             Actor actor,
@@ -619,6 +623,7 @@ public class GenerationCommands {
     @Command(name = "/ore", desc = "Generates ores")
     @CommandPermissions("worldedit.generation.ore")
     @Logging(PLACEMENT)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public void ore(
             Actor actor,

worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java

@@ -32,6 +32,7 @@ import com.sk89q.worldedit.command.util.CommandPermissions;
 import com.sk89q.worldedit.command.util.CommandPermissionsConditionGenerator;
 import com.sk89q.worldedit.command.util.Logging;
 import com.sk89q.worldedit.command.util.annotation.Confirm;
+import com.sk89q.worldedit.command.util.annotation.Preload;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.function.GroundFunction;
@@ -105,6 +106,7 @@ public class RegionCommands {
     @CommandPermissions("worldedit.region.set")
     @Logging(REGION)
     @Confirm(Confirm.Processor.REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     public int set(
             Actor actor, EditSession editSession,
             @Selection Region region,
@@ -125,6 +127,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.set")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     public void air(Actor actor, EditSession editSession, @Selection Region region) throws WorldEditException {
         set(actor, editSession, region, BlockTypes.AIR);
     }
@@ -305,6 +308,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.replace")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int replace(
             Actor actor, EditSession editSession, @Selection Region region,
@@ -351,6 +355,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.overlay")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public void lay(
             Player player,
@@ -429,6 +434,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.faces")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int faces(
             Actor actor, EditSession editSession, @Selection Region region,
@@ -447,6 +453,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.smooth")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int smooth(
             Actor actor, EditSession editSession, @Selection Region region,
@@ -522,6 +529,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.move")
     @Logging(ORIENTATION_REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int move(
             Actor actor, World world, EditSession editSession, LocalSession session,
@@ -586,6 +594,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.fall")
     @Logging(ORIENTATION_REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public void fall(
             Player player, EditSession editSession, LocalSession session,
@@ -604,6 +613,7 @@ public class RegionCommands {
             desc = "Repeat the contents of the selection"
     )
     @CommandPermissions("worldedit.region.stack")
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Logging(ORIENTATION_REGION)
     public int stack(
             Actor actor, World world, EditSession editSession, LocalSession session,
@@ -713,6 +723,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.deform")
     @Logging(ALL)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int deform(
             Actor actor, LocalSession session, EditSession editSession,
@@ -788,6 +799,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.hollow")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int hollow(
             Actor actor, EditSession editSession,
@@ -823,6 +835,7 @@ public class RegionCommands {
     )
     @CommandPermissions("worldedit.region.forest")
     @Logging(REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
     @Confirm(Confirm.Processor.REGION)
     public int forest(
             Actor actor, EditSession editSession, @Selection Region region,
@@ -853,7 +866,9 @@ public class RegionCommands {
         density = density / 100;
         FloraGenerator generator = new FloraGenerator(editSession);
         GroundFunction ground = new GroundFunction(new ExistingBlockMask(editSession), generator);
-        LayerVisitor visitor = new LayerVisitor(asFlatRegion(region), minimumBlockY(region), maximumBlockY(region), ground);
+        //FAWE start - provide extent for preloading
+        LayerVisitor visitor = new LayerVisitor(asFlatRegion(region), minimumBlockY(region), maximumBlockY(region), ground, editSession);
+        //FAWE end
         visitor.setMask(new NoiseFilter2D(new RandomNoise(), density));
         Operations.completeLegacy(visitor);
 

worldedit-core/src/main/java/com/sk89q/worldedit/command/tool/FloodFillTool.java

@@ -87,7 +87,7 @@ public class FloodFillTool implements BlockTool {
                 //FAWE start - Respect masks
                 Mask mask = initialType.toMask(editSession);
                 BlockReplace function = new BlockReplace(editSession, pattern);
-                RecursiveVisitor visitor = new RecursiveVisitor(mask, function, range);
+                RecursiveVisitor visitor = new RecursiveVisitor(mask, function, range, editSession);
                 visitor.visit(origin);
                 Operations.completeLegacy(visitor);
                 //FAWE end

worldedit-core/src/main/java/com/sk89q/worldedit/command/tool/RecursivePickaxe.java

@@ -86,7 +86,7 @@ public class RecursivePickaxe implements BlockTool {
             final int radius = (int) range;
             final BlockReplace replace = new BlockReplace(editSession, (BlockTypes.AIR.getDefaultState()));
             editSession.setMask(null);
-            RecursiveVisitor visitor = new RecursiveVisitor(new IdMask(editSession), replace, radius);
+            RecursiveVisitor visitor = new RecursiveVisitor(new IdMask(editSession), replace, radius, editSession);
             //TODO: Fix below
             //visitor.visit(pos);
             //Operations.completeBlindly(visitor);

worldedit-core/src/main/java/com/sk89q/worldedit/command/util/annotation/Preload.java

@@ -0,0 +1,46 @@
+package com.sk89q.worldedit.command.util.annotation;
+
+import com.fastasyncworldedit.core.Fawe;
+import com.fastasyncworldedit.core.queue.implementation.preloader.Preloader;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.extension.platform.Actor;
+import com.sk89q.worldedit.world.World;
+import org.enginehub.piston.inject.InjectAnnotation;
+import org.enginehub.piston.inject.InjectedValueAccess;
+import org.enginehub.piston.inject.Key;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Indicates how the affected blocks should be hinted at in the log.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({
+        ElementType.PARAMETER,
+        ElementType.METHOD
+})
+@InjectAnnotation
+public @interface Preload {
+
+    PreloadCheck value() default PreloadCheck.NEVER;
+
+    enum PreloadCheck {
+        PRELOAD {
+            @Override
+            public void preload(Actor actor, InjectedValueAccess context) {
+                World world = context.injectedValue(Key.of(EditSession.class)).get().getWorld();
+                Preloader preloader = Fawe.imp().getPreloader(true);
+                preloader.update(actor, world);
+            }
+        },
+
+        NEVER {};
+
+        public void preload(Actor actor, InjectedValueAccess context) {
+        }
+    }
+
+}

worldedit-core/src/main/java/com/sk89q/worldedit/command/util/annotation/PreloadHandler.java

@@ -0,0 +1,38 @@
+package com.sk89q.worldedit.command.util.annotation;
+
+import com.fastasyncworldedit.core.configuration.Settings;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.extension.platform.Actor;
+import org.enginehub.piston.CommandParameters;
+import org.enginehub.piston.gen.CommandCallListener;
+import org.enginehub.piston.inject.Key;
+
+import java.lang.reflect.Method;
+import java.util.Optional;
+
+/**
+ * Logs called commands to a logger.
+ */
+public class PreloadHandler implements CommandCallListener {
+
+    @Override
+    public void beforeCall(Method method, CommandParameters parameters) {
+        Preload preloadAnnotation = method.getAnnotation(Preload.class);
+        if (preloadAnnotation == null) {
+            return;
+        }
+        Optional<Actor> actorOpt = parameters.injectedValue(Key.of(Actor.class));
+        Optional<EditSession> editSessionOpt = parameters.injectedValue(Key.of(EditSession.class));
+
+        if (actorOpt.isEmpty() || editSessionOpt.isEmpty()) {
+            return;
+        }
+        Actor actor = actorOpt.get();
+        // Don't attempt to preload if effectively disabled
+        if (Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT <= 1) {
+            return;
+        }
+        preloadAnnotation.value().preload(actor, parameters);
+    }
+
+}

worldedit-core/src/main/java/com/sk89q/worldedit/command/util/annotation/package-info.java

@@ -6,6 +6,8 @@
  * @see com.sk89q.worldedit.command.util.annotation.ConfirmHandler
  * @see com.sk89q.worldedit.command.util.annotation.Link
  * @see com.sk89q.worldedit.command.util.annotation.PatternList
+ * @see com.sk89q.worldedit.command.util.annotation.Preload
+ * @see com.sk89q.worldedit.command.util.annotation.PreloadHandler
  * @see com.sk89q.worldedit.command.util.annotation.Step
  * @see com.sk89q.worldedit.command.util.annotation.Time
  */

worldedit-core/src/main/java/com/sk89q/worldedit/extension/platform/PlatformCommandManager.java

@@ -106,6 +106,7 @@ import com.sk89q.worldedit.command.util.PermissionCondition;
 import com.sk89q.worldedit.command.util.PrintCommandHelp;
 import com.sk89q.worldedit.command.util.SubCommandPermissionCondition;
 import com.sk89q.worldedit.command.util.annotation.ConfirmHandler;
+import com.sk89q.worldedit.command.util.annotation.PreloadHandler;
 import com.sk89q.worldedit.entity.Entity;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.event.Event;
@@ -219,7 +220,10 @@ public final class PlatformCommandManager {
                 ImmutableList.of(
                         new CommandLoggingHandler(worldEdit, COMMAND_LOG),
                         new MethodInjector(),
-                        new ConfirmHandler()
+                        //FAWE start
+                        new ConfirmHandler(),
+                        new PreloadHandler()
+                        //FAWE end
 
                 ));
         // setup separate from main constructor

worldedit-core/src/main/java/com/sk89q/worldedit/function/factory/ApplyLayer.java

@@ -55,7 +55,10 @@ public class ApplyLayer implements Contextual<Operation> {
                 localRegion,
                 localRegion.getMinimumPoint().getY(),
                 localRegion.getMaximumPoint().getY(),
-                function.createFromContext(context)
+                function.createFromContext(context),
+                //FAWE start - provide extent for preloading
+                context.getDestination()
+                //FAWE end
         );
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/function/factory/Paint.java

@@ -70,7 +70,9 @@ public class Paint implements Contextual<Operation> {
         Extent destination = firstNonNull(context.getDestination(), this.destination);
         Region region = firstNonNull(context.getRegion(), this.region);
         GroundFunction ground = new GroundFunction(new ExistingBlockMask(destination), function.createFromContext(context));
-        LayerVisitor visitor = new LayerVisitor(asFlatRegion(region), minimumBlockY(region), maximumBlockY(region), ground);
+        //FAWE start - provide extent for preloading
+        LayerVisitor visitor = new LayerVisitor(asFlatRegion(region), minimumBlockY(region), maximumBlockY(region), ground, destination);
+        //FAWE end
         visitor.setMask(new NoiseFilter2D(new RandomNoise(), density));
         return visitor;
     }

worldedit-core/src/main/java/com/sk89q/worldedit/function/operation/ForwardExtentCopy.java

@@ -27,6 +27,9 @@ import com.fastasyncworldedit.core.function.block.BiomeCopy;
 import com.fastasyncworldedit.core.function.block.CombinedBlockCopy;
 import com.fastasyncworldedit.core.function.block.SimpleBlockCopy;
 import com.fastasyncworldedit.core.function.visitor.IntersectRegionFunction;
+import com.fastasyncworldedit.core.queue.implementation.ParallelQueueExtent;
+import com.fastasyncworldedit.core.queue.implementation.SingleThreadQueueExtent;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
 import com.fastasyncworldedit.core.util.MaskTraverser;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
@@ -398,7 +401,9 @@ public class ForwardExtentCopy implements Operation {
             if (copyingBiomes && (source.isWorld() || region instanceof FlatRegion)) {
                 copy = CombinedRegionFunction.combine(copy, new BiomeCopy(source, finalDest));
             }
-            blockCopy = new RegionVisitor(region, copy);
+            ExtentTraverser<ParallelQueueExtent> queueTraverser = new ExtentTraverser<>(finalDest).find(ParallelQueueExtent.class);
+            Extent preloader = queueTraverser != null ? queueTraverser.get() : source;
+            blockCopy = new RegionVisitor(region, copy, preloader);
         }
 
         List<? extends Entity> entities;

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/BreadthFirstSearch.java

@@ -20,11 +20,16 @@
 package com.sk89q.worldedit.function.visitor;
 
 import com.fastasyncworldedit.core.configuration.Caption;
+import com.fastasyncworldedit.core.configuration.Settings;
 import com.fastasyncworldedit.core.math.BlockVectorSet;
 import com.fastasyncworldedit.core.math.MutableBlockVector3;
+import com.fastasyncworldedit.core.queue.implementation.ParallelQueueExtent;
+import com.fastasyncworldedit.core.queue.implementation.SingleThreadQueueExtent;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Sets;
 import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.RegionFunction;
 import com.sk89q.worldedit.function.operation.Operation;
 import com.sk89q.worldedit.function.operation.RunContext;
@@ -84,7 +89,8 @@ public abstract class BreadthFirstSearch implements Operation {
     //FAWE end
 
     private final RegionFunction function;
-    //FAWE Start - BVS > Queue<BV3>, Set<BV3>, List<BV3>
+    //FAWE start - allow chunk preloading and BVS > Queue<BV3>, Set<BV3>, List<BV3>
+    private final SingleThreadQueueExtent singleQueue;
     private BlockVectorSet queue = new BlockVectorSet();
     private BlockVectorSet visited = new BlockVectorSet();
     private BlockVector3[] directions;
@@ -108,11 +114,34 @@ public abstract class BreadthFirstSearch implements Operation {
     }
 
     //FAWE start
+    /**
+     * Create a new instance.
+     *
+     * @param function the function to apply to visited blocks
+     * @param maxDepth the maximum number of iterations
+     */
     public BreadthFirstSearch(RegionFunction function, int maxDepth) {
+        this(function, maxDepth, null);
+    }
+
+    /**
+     * Create a new instance.
+     *
+     * @param function the function to apply to visited blocks
+     * @param maxDepth the maximum number of iterations
+     * @param extent   extent to use for preloading
+     */
+    public BreadthFirstSearch(RegionFunction function, int maxDepth, Extent extent) {
         checkNotNull(function);
         this.function = function;
         this.directions = DEFAULT_DIRECTIONS;
         this.maxDepth = maxDepth;
+        if (extent != null) {
+            ExtentTraverser<ParallelQueueExtent> queueTraverser = new ExtentTraverser<>(extent).find(ParallelQueueExtent.class);
+            this.singleQueue = queueTraverser != null ? (SingleThreadQueueExtent) queueTraverser.get().getExtent() : null;
+        } else {
+            this.singleQueue = null;
+        }
     }
 
     public void setDirections(BlockVector3... directions) {
@@ -245,11 +274,39 @@ public abstract class BreadthFirstSearch implements Operation {
 
     @Override
     public Operation resume(RunContext run) throws WorldEditException {
-        //FAWE start - directions & visited
+        //FAWE start - directions, visited and preloading
         MutableBlockVector3 mutable = new MutableBlockVector3();
         BlockVector3[] dirs = directions;
         BlockVectorSet tempQueue = new BlockVectorSet();
+        BlockVectorSet chunkLoadSet = new BlockVectorSet();
         for (currentDepth = 0; !queue.isEmpty() && currentDepth <= maxDepth; currentDepth++) {
+            int loadCount = 0;
+            if (singleQueue != null && Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT > 1) {
+                int cx = Integer.MIN_VALUE;
+                int cz = Integer.MIN_VALUE;
+                outer: for (BlockVector3 from : queue) {
+                    for (BlockVector3 direction : dirs) {
+                        if (loadCount > Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT) {
+                            break outer;
+                        }
+                        int x = from.getBlockX() + direction.getBlockX();
+                        int z = from.getBlockZ() + direction.getBlockX();
+                        if (cx != (cx = x >> 4) || cz != (cz = z >> 4)) {
+                            int y = from.getBlockY() + direction.getBlockY();
+                            if (y < singleQueue.getMinY() || y > singleQueue.getMaxY()) {
+                                continue;
+                            }
+                            if (!visited.contains(x, y, z)) {
+                                loadCount++;
+                                chunkLoadSet.add(cx, 0, cz);
+                            }
+                        }
+                    }
+                }
+                for (BlockVector3 chunk : chunkLoadSet) {
+                    singleQueue.addChunkLoad(chunk.getBlockX(), chunk.getBlockZ());
+                }
+            }
             for (BlockVector3 from : queue) {
                 if (function.apply(from)) {
                     affected++;

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/DownwardVisitor.java

@@ -19,6 +19,7 @@
 
 package com.sk89q.worldedit.function.visitor;
 
+import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.RegionFunction;
 import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.math.BlockVector3;
@@ -48,10 +49,30 @@ public class DownwardVisitor extends RecursiveVisitor {
     public DownwardVisitor(Mask mask, RegionFunction function, int baseY) {
         this(mask, function, baseY, Integer.MAX_VALUE);
     }
-    //FAWE end
 
+    /**
+     * Create a new visitor.
+     *
+     * @param mask     the mask
+     * @param function the function
+     * @param baseY    the base Y
+     * @param depth    maximum number of iterations
+     */
     public DownwardVisitor(Mask mask, RegionFunction function, int baseY, int depth) {
-        super(mask, function, depth);
+        this (mask, function, baseY, depth, null);
+    }
+
+    /**
+     * Create a new visitor.
+     *
+     * @param mask     the mask
+     * @param function the function
+     * @param baseY    the base Y
+     * @param depth    maximum number of iterations
+     * @param extent   extent for preloading
+     */
+    public DownwardVisitor(Mask mask, RegionFunction function, int baseY, int depth, Extent extent) {
+        super(mask, function, depth, extent);
         checkNotNull(mask);
 
         this.baseY = baseY;
@@ -64,6 +85,7 @@ public class DownwardVisitor extends RecursiveVisitor {
                 BlockVector3.UNIT_MINUS_Y
         );
     }
+    //FAWE end
 
     @Override
     protected boolean isVisitable(BlockVector3 from, BlockVector3 to) {

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/FlatRegionVisitor.java

@@ -20,8 +20,12 @@
 package com.sk89q.worldedit.function.visitor;
 
 import com.fastasyncworldedit.core.configuration.Caption;
+import com.fastasyncworldedit.core.queue.implementation.ParallelQueueExtent;
+import com.fastasyncworldedit.core.queue.implementation.SingleThreadQueueExtent;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
 import com.google.common.collect.ImmutableList;
 import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.FlatRegionFunction;
 import com.sk89q.worldedit.function.operation.Operation;
 import com.sk89q.worldedit.function.operation.RunContext;
@@ -37,10 +41,14 @@ import static com.google.common.base.Preconditions.checkNotNull;
  */
 public class FlatRegionVisitor implements Operation {
 
+    //FAWE start - chunk preloading
+    private final SingleThreadQueueExtent singleQueue;
+    private final FlatRegion flatRegion;
+    //FAWE end
     private final FlatRegionFunction function;
     private int affected = 0;
-    private final Iterable<BlockVector2> iterator;
 
+    //FAWE start - chunk preloading
     /**
      * Create a new visitor.
      *
@@ -48,12 +56,30 @@ public class FlatRegionVisitor implements Operation {
      * @param function   a function to apply to columns
      */
     public FlatRegionVisitor(FlatRegion flatRegion, FlatRegionFunction function) {
+        this(flatRegion, function, null);
+    }
+
+    /**
+     * Create a new visitor.
+     *
+     * @param flatRegion a flat region
+     * @param function   a function to apply to columns
+     * @param extent     the extent for preloading
+     */
+    public FlatRegionVisitor(FlatRegion flatRegion, FlatRegionFunction function, Extent extent) {
         checkNotNull(flatRegion);
         checkNotNull(function);
 
         this.function = function;
-        this.iterator = flatRegion.asFlatRegion();
+        this.flatRegion = flatRegion;
+        if (extent != null) {
+            ExtentTraverser<ParallelQueueExtent> queueTraverser = new ExtentTraverser<>(extent).find(ParallelQueueExtent.class);
+            this.singleQueue = queueTraverser != null ? (SingleThreadQueueExtent) queueTraverser.get().getExtent() : null;
+        } else {
+            this.singleQueue = null;
         }
+    }
+    //FAWE end
 
     /**
      * Get the number of affected objects.
@@ -66,7 +92,12 @@ public class FlatRegionVisitor implements Operation {
 
     @Override
     public Operation resume(RunContext run) throws WorldEditException {
-        for (BlockVector2 pt : this.iterator) {
+        //FAWE start - chunk preloading
+        if (singleQueue != null) {
+            singleQueue.preload(flatRegion);
+        }
+        for (BlockVector2 pt : this.flatRegion.asFlatRegion()) {
+            //FAWE end
             if (function.apply(pt)) {
                 affected++;
             }

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/LayerVisitor.java

@@ -19,7 +19,13 @@
 
 package com.sk89q.worldedit.function.visitor;
 
+import com.fastasyncworldedit.core.configuration.Settings;
+import com.fastasyncworldedit.core.math.BlockVectorSet;
+import com.fastasyncworldedit.core.queue.implementation.ParallelQueueExtent;
+import com.fastasyncworldedit.core.queue.implementation.SingleThreadQueueExtent;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
 import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.LayerFunction;
 import com.sk89q.worldedit.function.mask.Mask2D;
 import com.sk89q.worldedit.function.mask.Masks;
@@ -29,6 +35,8 @@ import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.FlatRegion;
 
+import java.util.Set;
+
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -44,19 +52,38 @@ public class LayerVisitor implements Operation {
 
     private final FlatRegion flatRegion;
     private final LayerFunction function;
+    //FAWE start - chunk preloading
+    private final SingleThreadQueueExtent singleQueue;
+    //FAWE end
     private Mask2D mask = Masks.alwaysTrue2D();
     private final int minY;
     private final int maxY;
 
+
+    //FAWE start - chunk preloading
+    /**
+     * Create a new visitor.
+     *
+     * @param flatRegion the flat region to visit
+     * @param minY       the minimum Y to stop the search at
+     * @param maxY       the maximum Y to begin the search at
+     * @param function   the layer function to apply to blocks
+     */
+    public LayerVisitor(FlatRegion flatRegion, int minY, int maxY, LayerFunction function) {
+        this(flatRegion, minY, maxY, function, null);
+    }
+
     /**
      * Create a new visitor.
      *
      * @param flatRegion the flat region to visit
      * @param minY       the minimum Y to stop the search at
      * @param maxY       the maximum Y to begin the search at
-     * @param function   the layer function to apply t blocks
+     * @param function   the layer function to apply to blocks
+     * @param extent     the extent for preloading
      */
-    public LayerVisitor(FlatRegion flatRegion, int minY, int maxY, LayerFunction function) {
+    public LayerVisitor(FlatRegion flatRegion, int minY, int maxY, LayerFunction function, Extent extent) {
+        //FAWE end
         checkNotNull(flatRegion);
         checkArgument(minY <= maxY, "minY <= maxY required");
         checkNotNull(function);
@@ -65,6 +92,14 @@ public class LayerVisitor implements Operation {
         this.minY = minY;
         this.maxY = maxY;
         this.function = function;
+        //FAWE start - chunk preloading
+        if (extent != null) {
+            ExtentTraverser<ParallelQueueExtent> queueTraverser = new ExtentTraverser<>(extent).find(ParallelQueueExtent.class);
+            this.singleQueue = queueTraverser != null ? (SingleThreadQueueExtent) queueTraverser.get().getExtent() : null;
+        } else {
+            this.singleQueue = null;
+        }
+        //FAWE end
     }
 
     /**
@@ -90,6 +125,11 @@ public class LayerVisitor implements Operation {
 
     @Override
     public Operation resume(RunContext run) throws WorldEditException {
+        //FAWE start - chunk preloading
+        if (singleQueue != null) {
+            singleQueue.preload(flatRegion);
+        }
+        //FAWE end
         for (BlockVector2 column : flatRegion.asFlatRegion()) {
             if (!mask.test(column)) {
                 continue;

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/NonRisingVisitor.java

@@ -19,6 +19,7 @@
 
 package com.sk89q.worldedit.function.visitor;
 
+import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.RegionFunction;
 import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.math.BlockVector3;
@@ -41,9 +42,28 @@ public class NonRisingVisitor extends RecursiveVisitor {
     }
     //FAWE end
 
-    //FAWE start - int depth
+    //FAWE start - int depth, preloading
+    /**
+     * Create a new recursive visitor.
+     *
+     * @param mask     the mask
+     * @param function the function
+     * @param depth    the maximum number of iterations
+     */
     public NonRisingVisitor(Mask mask, RegionFunction function, int depth) {
-        super(mask, function, depth);
+        this(mask, function, depth, null);
+    }
+
+    /**
+     * Create a new recursive visitor.
+     *
+     * @param mask     the mask
+     * @param function the function
+     * @param depth    the maximum number of iterations
+     * @param extent   the extent for preloading
+     */
+    public NonRisingVisitor(Mask mask, RegionFunction function, int depth, Extent extent) {
+        super(mask, function, depth, extent);
         setDirections(
                 BlockVector3.UNIT_X,
                 BlockVector3.UNIT_MINUS_X,

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/RecursiveVisitor.java

@@ -19,6 +19,7 @@
 
 package com.sk89q.worldedit.function.visitor;
 
+import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.RegionFunction;
 import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.math.BlockVector3;
@@ -34,22 +35,41 @@ public class RecursiveVisitor extends BreadthFirstSearch {
     private final Mask mask;
 
     //FAWE start
-    public RecursiveVisitor(Mask mask, RegionFunction function) {
-        this(mask, function, Integer.MAX_VALUE);
-    }
-    //FAWE end
-
     /**
      * Create a new recursive visitor.
      *
      * @param mask     the mask
      * @param function the function
      */
+    public RecursiveVisitor(Mask mask, RegionFunction function) {
+        this(mask, function, Integer.MAX_VALUE);
+    }
+
+    /**
+     * Create a new recursive visitor.
+     *
+     * @param mask     the mask
+     * @param function the function
+     * @param maxDepth the maximum number of iterations
+     */
     public RecursiveVisitor(Mask mask, RegionFunction function, int maxDepth) {
-        super(function, maxDepth);
+        this(mask, function, maxDepth, null);
+    }
+
+    /**
+     * Create a new recursive visitor.
+     *
+     * @param mask     the mask
+     * @param function the function
+     * @param maxDepth the maximum number of iterations
+     * @param extent   the extent for preloading
+     */
+    public RecursiveVisitor(Mask mask, RegionFunction function, int maxDepth, Extent extent) {
+        super(function, maxDepth, extent);
         checkNotNull(mask);
         this.mask = mask;
     }
+    //FAWE end
 
     @Override
     protected boolean isVisitable(BlockVector3 from, BlockVector3 to) {

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/RegionVisitor.java

@@ -19,16 +19,12 @@
 
 package com.sk89q.worldedit.function.visitor;
 
-import com.fastasyncworldedit.core.Fawe;
 import com.fastasyncworldedit.core.configuration.Caption;
 import com.fastasyncworldedit.core.configuration.Settings;
 import com.fastasyncworldedit.core.internal.exception.FaweException;
 import com.fastasyncworldedit.core.queue.implementation.ParallelQueueExtent;
 import com.fastasyncworldedit.core.queue.implementation.SingleThreadQueueExtent;
-import com.fastasyncworldedit.core.queue.implementation.chunk.ChunkHolder;
 import com.fastasyncworldedit.core.util.ExtentTraverser;
-import com.fastasyncworldedit.core.util.MemUtil;
-import com.fastasyncworldedit.core.util.TaskManager;
 import com.google.common.collect.ImmutableList;
 import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.extent.Extent;
@@ -49,10 +45,12 @@ import java.util.Iterator;
 @Deprecated public class RegionVisitor implements Operation {
 
     public final Iterable<? extends BlockVector3> iterable;
+    //FAWE start - allow chunk preloading
+    private final SingleThreadQueueExtent singleQueue;
+    //FAWE end
     private final Region region;
     private final RegionFunction function;
     private int affected = 0;
-    private SingleThreadQueueExtent singleQueue;
 
     /**
      * @deprecated Use other constructors which will preload chunks during iteration
@@ -91,7 +89,7 @@ import java.util.Iterator;
 
     @Override public Operation resume(RunContext run) throws WorldEditException {
         //FAWE start > allow chunk preloading
-        if (singleQueue != null && Settings.IMP.QUEUE.PRELOAD_CHUNKS > 1) {
+        if (singleQueue != null && Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT > 1) {
             /*
              * The following is done to reduce iteration cost
              *  - Preload chunks just in time
@@ -105,7 +103,7 @@ import java.util.Iterator;
             int lastTrailChunkZ = Integer.MIN_VALUE;
             int lastLeadChunkX = Integer.MIN_VALUE;
             int lastLeadChunkZ = Integer.MIN_VALUE;
-            int loadingTarget = Settings.IMP.QUEUE.PRELOAD_CHUNKS;
+            int loadingTarget = Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT;
             try {
                 for (; ; ) {
                     BlockVector3 pt = trailIter.next();
@@ -130,7 +128,7 @@ import java.util.Iterator;
                             if (vcx != lastLeadChunkX || vcz != lastLeadChunkZ) {
                                 lastLeadChunkX = vcx;
                                 lastLeadChunkZ = vcz;
-                                queueChunkLoad(vcx, vcz);
+                                singleQueue.addChunkLoad(vcx, vcz);
                                 count++;
                             }
                             // Skip the next 15 blocks
@@ -196,18 +194,6 @@ import java.util.Iterator;
             affected++;
         }
     }
-
-    private void queueChunkLoad(int cx, int cz) {
-        TaskManager.IMP.sync(() -> {
-            boolean lowMem = MemUtil.isMemoryLimited();
-            if (!singleQueue.isQueueEnabled() || (!(lowMem && singleQueue.size() > Settings.IMP.QUEUE.PARALLEL_THREADS + 8)
-                && singleQueue.size() < Settings.IMP.QUEUE.TARGET_SIZE && Fawe.get().getQueueHandler().isUnderutilized())) {
-                //The GET chunk is what will take longest.
-                ((ChunkHolder)singleQueue.getOrCreateChunk(cx, cz)).getOrCreateGet();
-            }
-            return null;
-        });
-    }
     //FAWE end
 
     @Override public void cancel() {