Cheaper block writes and palette lookups

- ColumnExtentListeningHunk reports writes through a primitive listener instead of boxing ListeningHunk
- Palette layer generators memoized per seed slot instead of one shared recent entry

core/src/main/java/art/arcane/iris/generation/biome/IrisBiomePaletteLayer.java

@@ -47,6 +47,7 @@ import lombok.Setter;
 import lombok.experimental.Accessors;
 
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.atomic.AtomicReferenceArray;
 
 @Snippet("biome-palette")
 @Accessors(chain = true)
@@ -64,7 +65,8 @@ public class IrisBiomePaletteLayer {
             new LazyBoundedCache<>(LAYER_GENERATOR_CACHE_SIZE);
     @Getter(AccessLevel.NONE)
     @Setter(AccessLevel.NONE)
-    private final transient AtomicReference<CachedLayerGenerator> recentLayerGenerator = new AtomicReference<>();
+    private final transient AtomicReferenceArray<CachedLayerGenerator> recentLayerGenerators =
+            new AtomicReferenceArray<>(LAYER_GENERATOR_CACHE_SIZE);
     @Getter(AccessLevel.NONE)
     @Setter(AccessLevel.NONE)
     private final transient LazyBoundedCache<LayerGeneratorKey, CNG> heightGenerators =
@@ -145,7 +147,8 @@ public class IrisBiomePaletteLayer {
     public CNG getLayerGenerator(RNG parent, int signature, IrisData data) {
         Engine engine = data == null ? null : data.getEngine();
         long generatorSeed = parent.getSeed() + signature + minHeight + maxHeight + getBlockData(data).size();
-        CachedLayerGenerator recent = recentLayerGenerator.get();
+        int slot = (int) generatorSeed & (LAYER_GENERATOR_CACHE_SIZE - 1);
+        CachedLayerGenerator recent = recentLayerGenerators.getAcquire(slot);
         if (recent != null && recent.key.matches(data, engine, generatorSeed)) {
             return recent.generator;
         }
@@ -154,7 +157,7 @@ public class IrisBiomePaletteLayer {
         CNG generator = layerGenerators.computeIfAbsent(key,
                 ignored -> style.create(new RNG(generatorSeed), data, engine));
         if (generator != null) {
-            recentLayerGenerator.set(new CachedLayerGenerator(key, generator));
+            recentLayerGenerators.setRelease(slot, new CachedLayerGenerator(key, generator));
         }
         return generator;
     }

core/src/main/java/art/arcane/iris/generation/chunk/ColumnExtentListeningHunk.java

@@ -18,20 +18,50 @@
 
 package art.arcane.iris.generation.chunk;
 
-import art.arcane.volmlib.util.function.Consumer4;
 import art.arcane.volmlib.util.hunk.Hunk;
-import art.arcane.volmlib.util.hunk.view.ListeningHunk;
 
-public final class ColumnExtentListeningHunk<T> extends ListeningHunk<T> implements ColumnExtent {
+public final class ColumnExtentListeningHunk<T> implements Hunk<T>, ColumnExtent {
     private final Hunk<T> source;
+    private final Listener<T> listener;
 
-    public ColumnExtentListeningHunk(Hunk<T> source, Consumer4<Integer, Integer, Integer, T> listener) {
-        super(source, listener);
+    public ColumnExtentListeningHunk(Hunk<T> source, Listener<T> listener) {
         this.source = source;
+        this.listener = listener;
+    }
+
+    @Override
+    public void setRaw(int x, int y, int z, T t) {
+        listener.onWrite(x, y, z, t);
+        source.setRaw(x, y, z, t);
+    }
+
+    @Override
+    public T getRaw(int x, int y, int z) {
+        return source.getRaw(x, y, z);
+    }
+
+    @Override
+    public int getWidth() {
+        return source.getWidth();
+    }
+
+    @Override
+    public int getHeight() {
+        return source.getHeight();
+    }
+
+    @Override
+    public int getDepth() {
+        return source.getDepth();
     }
 
     @Override
     public int highestStoredY(int x, int z) {
         return ColumnExtent.highestStoredY(source, x, z);
     }
+
+    @FunctionalInterface
+    public interface Listener<T> {
+        void onWrite(int x, int y, int z, T value);
+    }
 }