Avoid allocations in the entity spawn listener hot path

src/main/java/org/mvplugins/multiverse/core/listeners/MVEntityListener.java

@@ -10,7 +10,9 @@
 import com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent;
 import com.dumptruckman.minecraft.util.Logging;
 import jakarta.inject.Inject;
+import org.bukkit.World;
 import org.bukkit.entity.Entity;
+import org.bukkit.entity.EntityType;
 import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Listener;
@@ -29,6 +31,7 @@
 import org.mvplugins.multiverse.core.dynamiclistener.annotations.EventClass;
 import org.mvplugins.multiverse.core.dynamiclistener.annotations.EventMethod;
 import org.mvplugins.multiverse.core.utils.compatibility.EntityCompatibility;
+import org.mvplugins.multiverse.core.world.LoadedMultiverseWorld;
 import org.mvplugins.multiverse.core.world.WorldManager;
 
 import java.util.Arrays;
@@ -102,14 +105,11 @@ public void onEvent(PreCreatureSpawnEvent event) {
                     return;
                 }
 
-                worldManager.getLoadedWorld(event.getSpawnLocation().getWorld())
-                        .peek(world -> {
-                            if (!world.getEntitySpawnConfig().shouldAllowSpawn(event.getType())) {
-                                Logging.finest("Cancelling Pre Creature Spawn Event for: " + event.getType());
-                                event.setCancelled(true);
-                                event.setShouldAbortSpawn(true);
-                            }
-                        });
+                if (!shouldAllowSpawn(event.getSpawnLocation().getWorld(), event.getType())) {
+                    Logging.finest("Cancelling Pre Creature Spawn Event for: " + event.getType());
+                    event.setCancelled(true);
+                    event.setShouldAbortSpawn(true);
+                }
             }
         };
     }
@@ -130,13 +130,10 @@ void creatureSpawn(CreatureSpawnEvent event) {
             return;
         }
 
-        worldManager.getLoadedWorld(event.getEntity().getWorld())
-                .peek(world -> {
-                    if (!world.getEntitySpawnConfig().shouldAllowSpawn(event.getEntityType())) {
-                        Logging.finest("Cancelling Creature Spawn Event for: " + event.getEntity());
-                        event.setCancelled(true);
-                    }
-                });
+        if (!shouldAllowSpawn(event.getEntity().getWorld(), event.getEntityType())) {
+            Logging.finest("Cancelling Creature Spawn Event for: " + event.getEntity());
+            event.setCancelled(true);
+        }
     }
 
     /**
@@ -149,13 +146,20 @@ void entitySpawn(EntitySpawnEvent event) {
             return;
         }
 
-        worldManager.getLoadedWorld(event.getEntity().getWorld())
-                .peek(world -> {
-                    if (!world.getEntitySpawnConfig().shouldAllowSpawn(event.getEntityType())) {
-                        Logging.finest("Cancelling Entity Spawn Event for: " + event.getEntity());
-                        event.setCancelled(true);
-                    }
-                });
+        if (!shouldAllowSpawn(event.getEntity().getWorld(), event.getEntityType())) {
+            Logging.finest("Cancelling Entity Spawn Event for: " + event.getEntity());
+            event.setCancelled(true);
+        }
+    }
+
+    /**
+     * Checks the world's spawn config. Spawn events fire thousands of times per second, so this avoids the
+     * Option and lambda allocations of {@link WorldManager#getLoadedWorld(World)}.
+     * Worlds not managed by Multiverse always allow the spawn.
+     */
+    private boolean shouldAllowSpawn(@Nullable World bukkitWorld, @NotNull EntityType entityType) {
+        LoadedMultiverseWorld world = worldManager.getLoadedWorldOrNull(bukkitWorld);
+        return world == null || world.getEntitySpawnConfig().shouldAllowSpawn(entityType);
     }
 
     @EventMethod

src/main/java/org/mvplugins/multiverse/core/world/WorldManager.java

@@ -1177,6 +1177,18 @@ public Option<LoadedMultiverseWorld> getLoadedWorld(@Nullable World world) {
         return Option.of(world).flatMap(notNullWorld -> getLoadedWorld(notNullWorld.getName()));
     }
 
+    /**
+     * Same as {@link #getLoadedWorld(World)}, but returns null instead of allocating an {@link Option}.
+     * Meant for hot paths such as entity spawn events.
+     *
+     * @param world The bukkit world that should be loaded.
+     * @return The multiverse world, or null if it is not a loaded multiverse world.
+     */
+    @ApiStatus.Internal
+    public @Nullable LoadedMultiverseWorld getLoadedWorldOrNull(@Nullable World world) {
+        return world == null ? null : worldStore.getLoadedWorldOrNull(world.getName());
+    }
+
     /**
      * Get a multiverse world that is loaded.
      *

src/main/java/org/mvplugins/multiverse/core/world/WorldStore.java

@@ -218,8 +218,13 @@ Option<LoadedMultiverseWorld> getLoadedWorld(@Nullable NamespacedKey worldKey) {
 
     @NotNull
     Option<LoadedMultiverseWorld> getLoadedWorld(@Nullable String worldKeyString) {
-        return Option.of(loadedMap.get(worldKeyString))
-                .filter(MultiverseWorld::isLoaded);
+        return Option.of(getLoadedWorldOrNull(worldKeyString));
+    }
+
+    @Nullable
+    LoadedMultiverseWorld getLoadedWorldOrNull(@Nullable String worldKeyString) {
+        LoadedMultiverseWorld world = loadedMap.get(worldKeyString);
+        return world != null && world.isLoaded() ? world : null;
     }
 
     boolean isLoadedWorld(@Nullable WorldKeyOrName keyOrName) {

src/main/java/org/mvplugins/multiverse/core/world/entity/EntitySpawnConfig.java

@@ -28,6 +28,11 @@ public final class EntitySpawnConfig {
     }
 
     public @NotNull SpawnCategoryConfig getSpawnCategoryConfig(@NotNull SpawnCategory spawnCategory) {
+        // Plain get first, so the common case does not allocate the capturing lambda below.
+        SpawnCategoryConfig spawnCategoryConfig = spawnCategoriesConfig.get(spawnCategory);
+        if (spawnCategoryConfig != null) {
+            return spawnCategoryConfig;
+        }
         return spawnCategoriesConfig.computeIfAbsent(spawnCategory,
                 computeSpawnCategory -> new SpawnCategoryConfig(
                         config,
@@ -40,9 +45,12 @@ public final class EntitySpawnConfig {
     public boolean shouldAllowSpawn(@NotNull EntityType entityType) {
         // Ensure it defaults to true if SpawnCategoryMapper fails to find a spawn category for the entity type,
         // to avoid accidentally breaking mob spawns.
-        return SpawnCategoryMapper.getSpawnCategory(entityType)
-                .map(spawnCategory -> getSpawnCategoryConfig(spawnCategory).shouldAllowSpawn(entityType))
-                .getOrElse(true);
+        // This runs for every spawn event, so it avoids Option and lambda allocations on purpose.
+        SpawnCategory spawnCategory = SpawnCategoryMapper.getSpawnCategoryOrNull(entityType);
+        if (spawnCategory == null) {
+            return true;
+        }
+        return getSpawnCategoryConfig(spawnCategory).shouldAllowSpawn(entityType);
     }
 
     public boolean shouldAllowSpawn(@NotNull Entity entity) {

src/main/java/org/mvplugins/multiverse/core/world/entity/SpawnCategoryMapper.java

@@ -100,7 +100,18 @@ public static void buildSpawnCategoryMap() {
      * @return The spawn category that the given entity type is in, or null if it cannot be determined
      */
     static @NotNull Option<SpawnCategory> getSpawnCategory(@Nullable EntityType entityType) {
-        return Option.of(entityTypeToSpawnCategoryMap.get(entityType));
+        return Option.of(getSpawnCategoryOrNull(entityType));
+    }
+
+    /**
+     * Gets the spawn category that the given entity type is in, without wrapping it in an {@link Option}.
+     * Meant for hot paths such as entity spawn events.
+     *
+     * @param entityType The entity type
+     * @return The spawn category that the given entity type is in, or null if it cannot be determined
+     */
+    static @Nullable SpawnCategory getSpawnCategoryOrNull(@Nullable EntityType entityType) {
+        return entityTypeToSpawnCategoryMap.get(entityType);
     }
 
     /**