From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: NONPLAYT <76615486+NONPLAYT@users.noreply.github.com>
Date: Wed, 12 Apr 2023 00:45:28 +0300
Subject: [PATCH] Replace shape full block cache with hashtable

This patch is based on the following mixins and classes:
* "me/jellysquid/mods/lithium/common/util/collections/Object2BooleanCacheTable.java"
* "me/jellysquid/mods/lithium/mixin/shapes/blockstate_cache/BlockMixin.java"

diff --git a/src/main/java/me/jellysquid/mods/lithium/common/util/collections/Object2BooleanCacheTable.java b/src/main/java/me/jellysquid/mods/lithium/common/util/collections/Object2BooleanCacheTable.java
new file mode 100644
index 0000000000000000000000000000000000000000..0a6ab285cb870cfff7cc6a3115353457903965cd
--- /dev/null
+++ b/src/main/java/me/jellysquid/mods/lithium/common/util/collections/Object2BooleanCacheTable.java
@@ -0,0 +1,60 @@
+package me.jellysquid.mods.lithium.common.util.collections;
+
+import it.unimi.dsi.fastutil.HashCommon;
+import net.minecraft.util.Mth;
+
+import java.util.function.Predicate;
+
+/**
+ * A lossy hashtable implementation that stores a mapping between an object and a boolean.
+ * <p>
+ * Any hash collisions will result in an overwrite: this is safe because the correct value can always be recomputed,
+ * given that the given operator is deterministic.
+ * <p>
+ * This implementation is safe to use from multiple threads
+ */
+public final class Object2BooleanCacheTable<T> {
+
+    private final int mask;
+    private final Node<T>[] nodes;
+    private final Predicate<T> operator;
+
+    @SuppressWarnings("unchecked")
+    public Object2BooleanCacheTable(int capacity, Predicate<T> operator) {
+        int capacity1 = Mth.smallestEncompassingPowerOfTwo(capacity);
+        this.mask = capacity1 - 1;
+        this.nodes = (Node<T>[]) new Node[capacity1];
+        this.operator = operator;
+    }
+
+    private static <T> int hash(T key) {
+        return HashCommon.mix(key.hashCode());
+    }
+
+    public boolean get(T key) {
+        int idx = hash(key) & this.mask;
+
+        Node<T> node = this.nodes[idx];
+        if (node != null && key.equals(node.key)) {
+            return node.value;
+        }
+
+        boolean test = this.operator.test(key);
+        this.nodes[idx] = new Node<>(key, test);
+
+        return test;
+    }
+
+    static class Node<T> {
+
+        final T key;
+        final boolean value;
+
+        Node(T key, boolean value) {
+            this.key = key;
+            this.value = value;
+        }
+
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/java/net/minecraft/world/level/block/Block.java b/src/main/java/net/minecraft/world/level/block/Block.java
index cc4a2bafc319fb54e8d1168cba85746c5dfafbc2..39121b8450c645f3ec003751f0716a9b102a7e5b 100644
--- a/src/main/java/net/minecraft/world/level/block/Block.java
+++ b/src/main/java/net/minecraft/world/level/block/Block.java
@@ -62,6 +62,7 @@ import net.minecraft.world.phys.shapes.BooleanOp;
 import net.minecraft.world.phys.shapes.Shapes;
 import net.minecraft.world.phys.shapes.VoxelShape;
 import org.slf4j.Logger;
+import me.jellysquid.mods.lithium.common.util.collections.Object2BooleanCacheTable;
 
 // Purpur start
 import net.minecraft.nbt.CompoundTag;
@@ -75,11 +76,12 @@ public class Block extends BlockBehaviour implements ItemLike {
     private static final Logger LOGGER = LogUtils.getLogger();
     private final Holder.Reference<Block> builtInRegistryHolder;
     public static final IdMapper<BlockState> BLOCK_STATE_REGISTRY = new IdMapper<>();
-    private static final LoadingCache<VoxelShape, Boolean> SHAPE_FULL_BLOCK_CACHE = CacheBuilder.newBuilder().maximumSize(512L).weakKeys().build(new CacheLoader<VoxelShape, Boolean>() {
-        public Boolean load(VoxelShape voxelshape) {
-            return !Shapes.joinIsNotEmpty(Shapes.block(), voxelshape, BooleanOp.NOT_SAME);
-        }
-    });
+    // DivineMC start - Replace shape full block cache with hashtable
+    private static final Object2BooleanCacheTable<VoxelShape> SHAPE_FULL_BLOCK_CACHE = new Object2BooleanCacheTable<>(
+            1536,
+            shape -> !Shapes.joinIsNotEmpty(Shapes.block(), shape, BooleanOp.NOT_SAME)
+    );
+    // DivineMC end
     public static final int UPDATE_NEIGHBORS = 1;
     public static final int UPDATE_CLIENTS = 2;
     public static final int UPDATE_INVISIBLE = 4;
@@ -290,7 +292,7 @@ public class Block extends BlockBehaviour implements ItemLike {
     }
 
     public static boolean isShapeFullBlock(VoxelShape shape) {
-        return (Boolean) Block.SHAPE_FULL_BLOCK_CACHE.getUnchecked(shape);
+        return Block.SHAPE_FULL_BLOCK_CACHE.get(shape); // DivineMC end - Replace shape full block cache with hashtable
     }
 
     public boolean propagatesSkylightDown(BlockState state, BlockGetter world, BlockPos pos) {