Spicy light update listening api.

- Round 1, no profiling done yet, not everything uses it.
 - WeakHashSet could be useful elsewhere, too.

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/ContraptionLighter.java

@@ -1,10 +1,15 @@
 package com.simibubi.create.content.contraptions.components.structureMovement;
 
+import net.minecraft.world.ILightReader;
+import net.minecraft.world.LightType;
+
 import com.simibubi.create.content.contraptions.components.structureMovement.render.RenderedContraption;
 import com.simibubi.create.foundation.render.backend.light.GridAlignedBB;
+import com.simibubi.create.foundation.render.backend.light.LightUpdateListener;
+import com.simibubi.create.foundation.render.backend.light.LightUpdater;
 import com.simibubi.create.foundation.render.backend.light.LightVolume;
 
-public abstract class ContraptionLighter<C extends Contraption> {
+public abstract class ContraptionLighter<C extends Contraption> implements LightUpdateListener {
     protected final C contraption;
     public final LightVolume lightVolume;
 
@@ -21,14 +26,8 @@ public abstract class ContraptionLighter<C extends Contraption> {
 
         lightVolume.initialize(contraption.entity.world);
         scheduleRebuild = true;
-    }
 
-    protected GridAlignedBB contraptionBoundsToVolume(GridAlignedBB bounds) {
+        startListening();
-        bounds.grow(1); // so we have at least enough data on the edges to avoid artifacts and have smooth lighting
-        bounds.minY = Math.max(bounds.minY, 0);
-        bounds.maxY = Math.min(bounds.maxY, 255);
-
-        return bounds;
     }
 
     public void tick(RenderedContraption owner) {
@@ -39,4 +38,26 @@ public abstract class ContraptionLighter<C extends Contraption> {
     }
 
     public abstract GridAlignedBB getContraptionBounds();
+
+    @Override
+    public void onLightUpdate(ILightReader world, LightType type, GridAlignedBB changed) {
+        lightVolume.notifyLightUpdate(world, type, changed);
+    }
+
+    @Override
+    public void onLightPacket(ILightReader world, int chunkX, int chunkZ) {
+        lightVolume.notifyLightPacket(world, chunkX, chunkZ);
+    }
+
+    protected void startListening() {
+        LightUpdater.getInstance().startListening(bounds, this);
+    }
+
+    protected GridAlignedBB contraptionBoundsToVolume(GridAlignedBB bounds) {
+        bounds.grow(1); // so we have at least enough data on the edges to avoid artifacts and have smooth lighting
+        bounds.minY = Math.max(bounds.minY, 0);
+        bounds.maxY = Math.min(bounds.maxY, 255);
+
+        return bounds;
+    }
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/NonStationaryLighter.java

@@ -25,6 +25,8 @@ public class NonStationaryLighter<C extends Contraption> extends ContraptionLigh
         if (!contraptionBounds.sameAs(bounds)) {
             lightVolume.move(contraption.entity.world, contraptionBoundsToVolume(contraptionBounds));
             bounds = contraptionBounds;
+
+            startListening();
         }
     }
 

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ActorInstance.java

@@ -17,6 +17,6 @@ public abstract class ActorInstance {
     public void beginFrame() { }
 
     protected int localBlockLight() {
-        return modelManager.contraption.renderWorld.getLightLevel(LightType.BLOCK, context.localPos);
+        return modelManager.getContraption().renderWorld.getLightLevel(LightType.BLOCK, context.localPos);
     }
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionKineticRenderer.java

@@ -20,16 +20,17 @@ import net.minecraft.world.gen.feature.template.Template;
 import org.apache.commons.lang3.tuple.Pair;
 
 import javax.annotation.Nullable;
+import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 
 public class ContraptionKineticRenderer extends InstancedTileRenderer<ContraptionProgram> {
 
     protected ArrayList<com.simibubi.create.content.contraptions.components.structureMovement.render.ActorInstance> actors = new ArrayList<>();
 
-    public final RenderedContraption contraption;
+    private final WeakReference<RenderedContraption> contraption;
 
     ContraptionKineticRenderer(RenderedContraption contraption) {
-        this.contraption = contraption;
+        this.contraption = new WeakReference<>(contraption);
     }
 
     @Override
@@ -77,6 +78,10 @@ public class ContraptionKineticRenderer extends InstancedTileRenderer<Contraptio
         return getMaterial(KineticRenderMaterials.ACTORS);
     }
 
+    public RenderedContraption getContraption() {
+        return contraption.get();
+    }
+
     @Override
     public BlockPos getOriginCoordinate() {
         return BlockPos.ZERO;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionRenderDispatcher.java

@@ -54,12 +54,6 @@ public class ContraptionRenderDispatcher {
     public static final Compartment<Pair<Contraption, Integer>> CONTRAPTION = new Compartment<>();
     protected static PlacementSimulationWorld renderWorld;
 
-    public static void notifyLightUpdate(ILightReader world, LightType type, SectionPos pos) {
-        for (RenderedContraption renderer : renderers.values()) {
-            renderer.getLighter().lightVolume.notifyLightUpdate(world, type, pos);
-        }
-    }
-
     public static void notifyLightPacket(ILightReader world, int chunkX, int chunkZ) {
         for (RenderedContraption renderer : renderers.values()) {
             renderer.getLighter().lightVolume.notifyLightPacket(world, chunkX, chunkZ);

src/main/java/com/simibubi/create/foundation/mixin/LightUpdateMixin.java

@@ -11,6 +11,7 @@ import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 import com.simibubi.create.content.contraptions.components.structureMovement.render.ContraptionRenderDispatcher;
 import com.simibubi.create.foundation.render.backend.light.ILightListener;
+import com.simibubi.create.foundation.render.backend.light.LightUpdater;
 
 import net.minecraft.client.multiplayer.ClientChunkProvider;
 import net.minecraft.util.math.SectionPos;
@@ -54,6 +55,6 @@ public abstract class LightUpdateMixin extends AbstractChunkProvider {
             });
         }
 
-        ContraptionRenderDispatcher.notifyLightUpdate(world, type, pos);
+        LightUpdater.getInstance().onLightUpdate(world, type, pos.asLong());
     }
 }

src/main/java/com/simibubi/create/foundation/mixin/NetworkLightUpdateMixin.java

@@ -1,13 +1,19 @@
 package com.simibubi.create.foundation.mixin;
 
+import com.simibubi.create.CreateClient;
 import com.simibubi.create.content.contraptions.components.structureMovement.render.ContraptionRenderDispatcher;
 import com.simibubi.create.foundation.render.backend.RenderWork;
 import com.simibubi.create.foundation.render.backend.light.ILightListener;
+import com.simibubi.create.foundation.render.backend.light.LightUpdater;
+
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.network.play.ClientPlayNetHandler;
 import net.minecraft.client.world.ClientWorld;
 import net.minecraft.network.play.server.SUpdateLightPacket;
+import net.minecraft.util.math.SectionPos;
 import net.minecraft.world.chunk.Chunk;
+
+import java.util.Map;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
@@ -30,14 +36,16 @@ public class NetworkLightUpdateMixin {
 
             if (chunk != null) {
                 chunk.getTileEntityMap()
-                     .values()
+                        .values()
-                     .stream()
+                        .forEach(tile -> {
-                     .filter(tile -> tile instanceof ILightListener)
+                            CreateClient.kineticRenderer.get(world).onLightUpdate(tile);
-                     .map(tile -> (ILightListener) tile)
+
-                     .forEach(ILightListener::onChunkLightUpdate);
+                            if (tile instanceof ILightListener)
+                                ((ILightListener) tile).onChunkLightUpdate();
+                        });
             }
 
-            ContraptionRenderDispatcher.notifyLightPacket(world, chunkX, chunkZ);
+            LightUpdater.getInstance().onLightPacket(world, chunkX, chunkZ);
         });
     }
 }

src/main/java/com/simibubi/create/foundation/render/backend/light/LightUpdateListener.java

@@ -0,0 +1,26 @@
+package com.simibubi.create.foundation.render.backend.light;
+
+import net.minecraft.world.ILightReader;
+import net.minecraft.world.LightType;
+
+/**
+ * Anything can implement this, implementors should call {@link LightUpdater#startListening}
+ * appropriately to make sure they get the updates they want.
+ */
+public interface LightUpdateListener {
+
+	/**
+	 * Called when a light updates in a chunk the implementor cares about.
+	 */
+	void onLightUpdate(ILightReader world, LightType type, GridAlignedBB changed);
+
+	/**
+	 * Called when the server sends light data to the client.
+	 */
+	default void onLightPacket(ILightReader world, int chunkX, int chunkZ) {
+		GridAlignedBB changedVolume = GridAlignedBB.fromChunk(chunkX, chunkZ);
+
+		onLightUpdate(world, LightType.BLOCK, changedVolume);
+		onLightUpdate(world, LightType.SKY, changedVolume);
+	}
+}

src/main/java/com/simibubi/create/foundation/render/backend/light/LightUpdater.java

@@ -0,0 +1,198 @@
+package com.simibubi.create.foundation.render.backend.light;
+
+import it.unimi.dsi.fastutil.longs.Long2ObjectMap;
+import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
+import it.unimi.dsi.fastutil.longs.LongRBTreeSet;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.SectionPos;
+import net.minecraft.world.ILightReader;
+import net.minecraft.world.LightType;
+
+import java.util.*;
+import java.util.function.LongConsumer;
+import com.simibubi.create.foundation.utility.WeakHashSet;
+
+/**
+ * By using WeakReferences we can automatically remove listeners when they are garbage collected.
+ * This allows us to easily be more clever about how we store the listeners. Each listener is associated
+ * with 2 sets of longs indicating what chunks and sections each listener is in. Additionally, a reverse
+ * mapping is created to allow for fast lookups when light updates. The reverse mapping is more interesting,
+ * but {@link #listenersToSections}, and {@link #listenersToChunks} are used to know what sections and
+ * chunks we need to remove the listeners from if they re-subscribe. Otherwise, listeners could get updates
+ * they no longer care about. This is done in {@link #clearSections} and {@link #clearChunks}
+ */
+public class LightUpdater {
+
+	private static LightUpdater instance;
+
+	public static LightUpdater getInstance() {
+		if (instance == null)
+			instance = new LightUpdater();
+
+		return instance;
+	}
+
+	private final Long2ObjectMap<WeakHashSet<LightUpdateListener>> sections;
+	private final WeakHashMap<LightUpdateListener, LongRBTreeSet> listenersToSections;
+
+	private final Long2ObjectMap<WeakHashSet<LightUpdateListener>> chunks;
+	private final WeakHashMap<LightUpdateListener, LongRBTreeSet> listenersToChunks;
+
+	public LightUpdater() {
+		sections = new Long2ObjectOpenHashMap<>();
+		listenersToSections = new WeakHashMap<>();
+
+		chunks = new Long2ObjectOpenHashMap<>();
+		listenersToChunks = new WeakHashMap<>();
+	}
+
+	/**
+	 * Add a listener associated with the given {@link BlockPos}.
+	 *
+	 * When a light update occurs in the chunk the position is contained in,
+	 * {@link LightUpdateListener#onLightUpdate} will be called.
+	 *
+	 * @param pos The position in the world that the listener cares about.
+	 * @param listener The object that wants to receive light update notifications.
+	 */
+	public void startListening(BlockPos pos, LightUpdateListener listener) {
+		LongRBTreeSet sections = clearSections(listener);
+		LongRBTreeSet chunks = clearChunks(listener);
+
+		long sectionPos = worldToSection(pos);
+		addToSection(sectionPos, listener);
+		sections.add(sectionPos);
+
+		long chunkPos = sectionToChunk(sectionPos);
+		addToChunk(chunkPos, listener);
+		chunks.add(chunkPos);
+	}
+
+	/**
+	 * Add a listener associated with the given {@link GridAlignedBB}.
+	 *
+	 * When a light update occurs in any chunk spanning the given volume,
+	 * {@link LightUpdateListener#onLightUpdate} will be called.
+	 *
+	 * @param volume The volume in the world that the listener cares about.
+	 * @param listener The object that wants to receive light update notifications.
+	 */
+	public void startListening(GridAlignedBB volume, LightUpdateListener listener) {
+		LongRBTreeSet sections = clearSections(listener);
+		LongRBTreeSet chunks = clearSections(listener);
+
+		int minX = SectionPos.toChunk(volume.minX);
+		int minY = SectionPos.toChunk(volume.minY);
+		int minZ = SectionPos.toChunk(volume.minZ);
+		int maxX = SectionPos.toChunk(volume.maxX);
+		int maxY = SectionPos.toChunk(volume.maxY);
+		int maxZ = SectionPos.toChunk(volume.maxZ);
+
+		for (int x = minX; x <= maxX; x++) {
+			for (int z = minZ; z <= maxZ; z++) {
+				for (int y = minY; y <= maxY; y++) {
+					long sectionPos = SectionPos.asLong(x, y, z);
+					addToSection(sectionPos, listener);
+					sections.add(sectionPos);
+				}
+				long chunkPos = SectionPos.asLong(x, 0, z);
+				addToChunk(chunkPos, listener);
+				chunks.add(chunkPos);
+			}
+		}
+	}
+
+	/**
+	 * Dispatch light updates to all registered {@link LightUpdateListener}s.
+	 *
+	 * @param world The world in which light was updated.
+	 * @param type The type of light that changed.
+	 * @param sectionPos A long representing the section position where light changed.
+	 */
+	public void onLightUpdate(ILightReader world, LightType type, long sectionPos) {
+		WeakHashSet<LightUpdateListener> set = sections.get(sectionPos);
+
+		if (set == null || set.isEmpty()) return;
+
+		GridAlignedBB chunkBox = GridAlignedBB.fromSection(SectionPos.from(sectionPos));
+
+		for (LightUpdateListener listener : set) {
+			listener.onLightUpdate(world, type, chunkBox.copy());
+		}
+
+	}
+
+	/**
+	 * Dispatch light updates to all registered {@link LightUpdateListener}s
+	 * when the server sends lighting data for an entire chunk.
+	 *
+	 * @param world The world in which light was updated.
+	 */
+	public void onLightPacket(ILightReader world, int chunkX, int chunkZ) {
+
+		long chunkPos = SectionPos.asLong(chunkX, 0, chunkZ);
+
+		WeakHashSet<LightUpdateListener> set = chunks.get(chunkPos);
+
+		if (set == null || set.isEmpty()) return;
+
+		for (LightUpdateListener listener : set) {
+			listener.onLightPacket(world, chunkX, chunkZ);
+		}
+
+	}
+
+	private LongRBTreeSet clearChunks(LightUpdateListener listener) {
+		return clear(listener, listenersToChunks, chunks);
+	}
+
+	private LongRBTreeSet clearSections(LightUpdateListener listener) {
+		return clear(listener, listenersToSections, sections);
+	}
+
+	private LongRBTreeSet clear(LightUpdateListener listener, WeakHashMap<LightUpdateListener, LongRBTreeSet> listeners, Long2ObjectMap<WeakHashSet<LightUpdateListener>> lookup) {
+		LongRBTreeSet set = listeners.get(listener);
+
+		if (set == null) {
+			set = new LongRBTreeSet();
+			listeners.put(listener, set);
+		} else {
+			set.forEach((LongConsumer) l -> {
+				WeakHashSet<LightUpdateListener> listeningSections = lookup.get(l);
+
+				if (listeningSections != null) listeningSections.remove(listener);
+			});
+
+			set.clear();
+		}
+
+		return set;
+	}
+
+	private void addToSection(long sectionPos, LightUpdateListener listener) {
+		getOrCreate(sections, sectionPos).add(listener);
+	}
+
+	private void addToChunk(long chunkPos, LightUpdateListener listener) {
+		getOrCreate(chunks, chunkPos).add(listener);
+	}
+
+	private WeakHashSet<LightUpdateListener> getOrCreate(Long2ObjectMap<WeakHashSet<LightUpdateListener>> sections, long chunkPos) {
+		WeakHashSet<LightUpdateListener> set = sections.get(chunkPos);
+
+		if (set == null) {
+			set = new WeakHashSet<>();
+			sections.put(chunkPos, set);
+		}
+
+		return set;
+	}
+
+	public static long worldToSection(BlockPos pos) {
+		return SectionPos.asLong(pos.getX(), pos.getY(), pos.getZ());
+	}
+
+	public static long sectionToChunk(long sectionPos) {
+		return sectionPos & 0xFFFFFFFFFFF_00000L;
+	}
+}

src/main/java/com/simibubi/create/foundation/render/backend/light/LightVolume.java

@@ -123,17 +123,21 @@ public class LightVolume {
         }
     }
 
-    public void notifyLightUpdate(ILightReader world, LightType type, SectionPos location) {
+    public void notifyLightUpdate(ILightReader world, LightType type, GridAlignedBB changedVolume) {
-        GridAlignedBB changedVolume = GridAlignedBB.fromSection(location);
+        if (removed)
+            return;
+
         if (!changedVolume.intersects(sampleVolume))
             return;
-        changedVolume.intersectAssign(sampleVolume); // compute the region contained by us that has dirty lighting data.
+        changedVolume = changedVolume.intersect(sampleVolume); // compute the region contained by us that has dirty lighting data.
 
         if (type == LightType.BLOCK) copyBlock(world, changedVolume);
         else if (type == LightType.SKY) copySky(world, changedVolume);
     }
 
     public void notifyLightPacket(ILightReader world, int chunkX, int chunkZ) {
+        if (removed) return;
+
         GridAlignedBB changedVolume = GridAlignedBB.fromChunk(chunkX, chunkZ);
         if (!changedVolume.intersects(sampleVolume))
             return;

src/main/java/com/simibubi/create/foundation/utility/WeakHashSet.java

@@ -0,0 +1,114 @@
+package com.simibubi.create.foundation.utility;
+
+import net.minecraft.util.Unit;
+
+import java.util.*;
+
+public class WeakHashSet<T> extends AbstractSet<T> {
+
+	WeakHashMap<T, Unit> map;
+
+	public WeakHashSet() {
+		map = new WeakHashMap<>();
+	}
+
+	/**
+	 * Constructs a new set containing the elements in the specified
+	 * collection.  The <tt>HashMap</tt> is created with default load factor
+	 * (0.75) and an initial capacity sufficient to contain the elements in
+	 * the specified collection.
+	 *
+	 * @param c the collection whose elements are to be placed into this set
+	 * @throws NullPointerException if the specified collection is null
+	 */
+	public WeakHashSet(Collection<? extends T> c) {
+		map = new WeakHashMap<>(Math.max((int) (c.size()/.75f) + 1, 16));
+		addAll(c);
+	}
+
+	/**
+	 * Constructs a new, empty set; the backing <tt>HashMap</tt> instance has
+	 * the specified initial capacity and the specified load factor.
+	 *
+	 * @param      initialCapacity   the initial capacity of the hash map
+	 * @param      loadFactor        the load factor of the hash map
+	 * @throws     IllegalArgumentException if the initial capacity is less
+	 *             than zero, or if the load factor is nonpositive
+	 */
+	public WeakHashSet(int initialCapacity, float loadFactor) {
+		map = new WeakHashMap<>(initialCapacity, loadFactor);
+	}
+
+	/**
+	 * Constructs a new, empty set; the backing <tt>HashMap</tt> instance has
+	 * the specified initial capacity and default load factor (0.75).
+	 *
+	 * @param      initialCapacity   the initial capacity of the hash table
+	 * @throws     IllegalArgumentException if the initial capacity is less
+	 *             than zero
+	 */
+	public WeakHashSet(int initialCapacity) {
+		map = new WeakHashMap<>(initialCapacity);
+	}
+
+
+	@Override
+	public Iterator<T> iterator() {
+		return map.keySet().iterator();
+	}
+
+	@Override
+	public int size() {
+		return map.size();
+	}
+
+	@Override
+	public boolean add(T t) {
+		return map.put(t, Unit.INSTANCE) == null;
+	}
+
+	@Override
+	public boolean remove(Object o) {
+		return map.remove((T) o) != null;
+	}
+
+	@Override
+	public boolean isEmpty() {
+		return map.isEmpty();
+	}
+
+	@Override
+	public boolean contains(Object o) {
+		return map.containsKey((T) o);
+	}
+
+	@Override
+	public Object[] toArray() {
+		return map.keySet().toArray();
+	}
+
+	@Override
+	public boolean containsAll(Collection<?> c) {
+		return c.stream().allMatch(map::containsKey);
+	}
+
+	@Override
+	public boolean addAll(Collection<? extends T> c) {
+		return false;
+	}
+
+	@Override
+	public boolean retainAll(Collection<?> c) {
+		return false;
+	}
+
+	@Override
+	public boolean removeAll(Collection<?> c) {
+		return false;
+	}
+
+	@Override
+	public void clear() {
+		map.clear();
+	}
+}