PaperMC/paper-server/patches/features/0023-Entity-load-save-limit-per-chunk.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jason Penilla <11360596+jpenilla@users.noreply.github.com>
Date: Wed, 18 Nov 2020 20:52:25 -0800
Subject: [PATCH] Entity load/save limit per chunk

Adds a config option to limit the number of entities saved and loaded
to a chunk. The default values of -1 disable the limit. Although
defaults are only included for certain entites, this allows setting
limits for any entity type.

diff --git a/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/ChunkEntitySlices.java b/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/ChunkEntitySlices.java
index 7aea4e343581b977d11af90f9f65eac3532eade1..d21ce54ebb5724c04eadf56a2cde701d5eeb5db2 100644
--- a/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/ChunkEntitySlices.java
+++ b/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/ChunkEntitySlices.java
@@ -104,7 +104,18 @@ public final class ChunkEntitySlices {
         }
 
         final ListTag entitiesTag = new ListTag();
+        final java.util.Map<net.minecraft.world.entity.EntityType<?>, Integer> savedEntityCounts = new java.util.HashMap<>(); // Paper - Entity load/save limit per chunk
         for (final Entity entity : PlatformHooks.get().modifySavedEntities(world, chunkPos.x, chunkPos.z, entities)) {
+            // Paper start - Entity load/save limit per chunk
+            final EntityType<?> entityType = entity.getType();
+            final int saveLimit = world.paperConfig().chunks.entityPerChunkSaveLimit.getOrDefault(entityType, -1);
+            if (saveLimit > -1) {
+                if (savedEntityCounts.getOrDefault(entityType, 0) >= saveLimit) {
+                    continue;
+                }
+                savedEntityCounts.merge(entityType, 1, Integer::sum);
+            }
+            // Paper end - Entity load/save limit per chunk
             CompoundTag compoundTag = new CompoundTag();
             if (entity.save(compoundTag)) {
                 entitiesTag.add(compoundTag);
diff --git a/net/minecraft/world/entity/EntityType.java b/net/minecraft/world/entity/EntityType.java
index 73cdfa5a315ed259b38dfa946a0b7955d9ac9f50..49201d6664656ebe34c84c1c84b5ea4878729062 100644
--- a/net/minecraft/world/entity/EntityType.java
+++ b/net/minecraft/world/entity/EntityType.java
@@ -1420,9 +1420,20 @@ public class EntityType<T extends Entity> implements FeatureElement, EntityTypeT
     public static Stream<Entity> loadEntitiesRecursive(final List<? extends Tag> entityTags, final Level level, final EntitySpawnReason spawnReason) {
         final Spliterator<? extends Tag> spliterator = entityTags.spliterator();
         return StreamSupport.stream(new Spliterator<Entity>() {
+            final java.util.Map<EntityType<?>, Integer> loadedEntityCounts = new java.util.HashMap<>(); // Paper - Entity load/save limit per chunk
             @Override
             public boolean tryAdvance(Consumer<? super Entity> consumer) {
                 return spliterator.tryAdvance(tag -> EntityType.loadEntityRecursive((CompoundTag)tag, level, spawnReason, entity -> {
+                        // Paper start - Entity load/save limit per chunk
+                        final EntityType<?> entityType = entity.getType();
+                        final int saveLimit = level.paperConfig().chunks.entityPerChunkSaveLimit.getOrDefault(entityType, -1);
+                        if (saveLimit > -1) {
+                            if (this.loadedEntityCounts.getOrDefault(entityType, 0) >= saveLimit) {
+                                return null;
+                            }
+                            this.loadedEntityCounts.merge(entityType, 1, Integer::sum);
+                        }
+                        // Paper end - Entity load/save limit per chunk
                     consumer.accept(entity);
                     return entity;
                 }));
diff --git a/net/minecraft/world/level/chunk/storage/EntityStorage.java b/net/minecraft/world/level/chunk/storage/EntityStorage.java
index da05fb780c55381a7a08ced51d01764a645740b2..2856206eafddfcbcc1b65408deda40357f43a6f8 100644
--- a/net/minecraft/world/level/chunk/storage/EntityStorage.java
+++ b/net/minecraft/world/level/chunk/storage/EntityStorage.java
@@ -93,7 +93,18 @@ public class EntityStorage implements EntityPersistentStorage<Entity> {
             }
         } else {
             ListTag listTag = new ListTag();
+            final java.util.Map<net.minecraft.world.entity.EntityType<?>, Integer> savedEntityCounts = new java.util.HashMap<>(); // Paper - Entity load/save limit per chunk
             entities.getEntities().forEach(entity -> {
+                // Paper start - Entity load/save limit per chunk
+                final EntityType<?> entityType = entity.getType();
+                final int saveLimit = this.level.paperConfig().chunks.entityPerChunkSaveLimit.getOrDefault(entityType, -1);
+                if (saveLimit > -1) {
+                    if (savedEntityCounts.getOrDefault(entityType, 0) >= saveLimit) {
+                        return;
+                    }
+                    savedEntityCounts.merge(entityType, 1, Integer::sum);
+                }
+                // Paper end - Entity load/save limit per chunk
                 CompoundTag compoundTag1 = new CompoundTag();
                 if (entity.save(compoundTag1)) {
                     listTag.add(compoundTag1);