replace hash map of spawn limit with array (#492)

* replace hash map of spawn limit with enum map

* [ci/skip] Add missing comment

leaf-server/paper-patches/features/0057-optimize-mob-spawning.patch

@@ -4,6 +4,92 @@ Date: Sat, 5 Jul 2025 17:01:43 +0900
 Subject: [PATCH] optimize mob spawning
 
 
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+index dfafd3125438b6a74f15a749599acfd00918c50a..034d136bcaa894d8999fc51a53d66b40bb884ccd 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+@@ -296,7 +296,8 @@ public final class CraftServer implements Server {
+     private final EntityMetadataStore entityMetadata = new EntityMetadataStore();
+     private final PlayerMetadataStore playerMetadata = new PlayerMetadataStore();
+     private final WorldMetadataStore worldMetadata = new WorldMetadataStore();
+-    private final Object2IntOpenHashMap<SpawnCategory> spawnCategoryLimit = new Object2IntOpenHashMap<>();
++    private static final SpawnCategory[] SPAWN_CATEGORIES = SpawnCategory.values(); // Leaf - optimize mob spawning
++    private final int[] spawnCategoryLimit = new int[SPAWN_CATEGORIES.length]; // Leaf - optimize mob spawning
+     private File container;
+     private WarningState warningState = WarningState.DEFAULT;
+     public ApiVersion minimumAPI;
+@@ -497,6 +498,7 @@ public final class CraftServer implements Server {
+         this.saveCommandsConfig();
+         this.overrideAllCommandBlockCommands = this.commandsConfiguration.getStringList("command-block-overrides").contains("*");
+         this.ignoreVanillaPermissions = this.commandsConfiguration.getBoolean("ignore-vanilla-permissions");
++        java.util.Arrays.fill(spawnCategoryLimit, -1); // Leaf - optimize mob spawning
+         this.overrideSpawnLimits();
+         console.autosavePeriod = this.configuration.getInt("ticks-per.autosave");
+         this.warningState = WarningState.value(this.configuration.getString("settings.deprecated-verbose"));
+@@ -529,9 +531,9 @@ public final class CraftServer implements Server {
+     }
+ 
+     private void overrideSpawnLimits() {
+-        for (SpawnCategory spawnCategory : SpawnCategory.values()) {
++        for (SpawnCategory spawnCategory : SPAWN_CATEGORIES) { // Leaf - optimize mob spawning
+             if (CraftSpawnCategory.isValidForLimits(spawnCategory)) {
+-                this.spawnCategoryLimit.put(spawnCategory, this.configuration.getInt(CraftSpawnCategory.getConfigNameSpawnLimit(spawnCategory)));
++                this.spawnCategoryLimit[spawnCategory.ordinal()] = this.configuration.getInt(CraftSpawnCategory.getConfigNameSpawnLimit(spawnCategory)); // Leaf - optimize mob spawning
+             }
+         }
+     }
+@@ -2544,7 +2546,7 @@ public final class CraftServer implements Server {
+     }
+ 
+     public int getSpawnLimitUnsafe(final SpawnCategory spawnCategory) {
+-        return this.spawnCategoryLimit.getOrDefault(spawnCategory, -1);
++        return this.spawnCategoryLimit[spawnCategory.ordinal()]; // Leaf - optimize mob spawning
+     }
+ 
+     @Override
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+index ee5f342995a335593932a497c2bafd36d34cecb2..2523cd17ad4a3add3a9a420777dc49fe0658fe01 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+@@ -173,7 +173,8 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+     private final @Nullable BiomeProvider biomeProvider;
+     private final List<BlockPopulator> populators = new ArrayList<BlockPopulator>();
+     private final BlockMetadataStore blockMetadata = new BlockMetadataStore(this);
+-    private final Object2IntOpenHashMap<SpawnCategory> spawnCategoryLimit = new Object2IntOpenHashMap<>();
++    private static final SpawnCategory[] SPAWN_CATEGORIES = SpawnCategory.values(); // Leaf - optimize mob spawning
++    private final int[] spawnCategoryLimit = new int[SPAWN_CATEGORIES.length]; // Leaf - optimize mob spawning
+     private final CraftPersistentDataContainer persistentDataContainer = new CraftPersistentDataContainer(CraftWorld.DATA_TYPE_REGISTRY);
+     // Paper start - void damage configuration
+     private boolean voidDamageEnabled;
+@@ -303,8 +304,9 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+         this.biomeProvider = biomeProvider;
+ 
+         this.environment = environment;
++        Arrays.fill(spawnCategoryLimit, -1); // Leaf - optimize mob spawning
+         // Paper start - per world spawn limits
+-        for (SpawnCategory spawnCategory : SpawnCategory.values()) {
++        for (SpawnCategory spawnCategory : SPAWN_CATEGORIES) { // Leaf - optimize mob spawning
+             if (CraftSpawnCategory.isValidForLimits(spawnCategory)) {
+                 setSpawnLimit(spawnCategory, this.world.paperConfig().entities.spawning.spawnLimits.getInt(CraftSpawnCategory.toNMS(spawnCategory)));
+             }
+@@ -1868,7 +1870,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+         return this.getSpawnLimitUnsafe(spawnCategory);
+     }
+     public final int getSpawnLimitUnsafe(final SpawnCategory spawnCategory) {
+-        int limit = this.spawnCategoryLimit.getOrDefault(spawnCategory, -1);
++        int limit = this.spawnCategoryLimit[spawnCategory.ordinal()]; // Leaf - optimize mob spawning
+         if (limit < 0) {
+             limit = this.server.getSpawnLimitUnsafe(spawnCategory);
+             // Paper end - Add mobcaps commands
+@@ -1881,7 +1883,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+         Preconditions.checkArgument(spawnCategory != null, "SpawnCategory cannot be null");
+         Preconditions.checkArgument(CraftSpawnCategory.isValidForLimits(spawnCategory), "SpawnCategory.%s are not supported", spawnCategory);
+ 
+-        this.spawnCategoryLimit.put(spawnCategory, limit);
++        this.spawnCategoryLimit[spawnCategory.ordinal()] = limit; // Leaf - optimize mob spawning
+     }
+ 
+     @Override
 diff --git a/src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java b/src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java
 index 348bf5ed91ded3537a86bc0708e0158ad4f9296d..7a7d0b8c0b5e6d9b58ca973972bac488975e6e2a 100644
 --- a/src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java