paper-mc/paper-server/patches/features/0021-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 c380487a97f626163e1f13d87231d64ce2ea4b24..b2bcfb3557a0326fd7ec1059f95d6da4568dfd80 100644
--- a/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/ChunkEntitySlices.java
+++ b/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/ChunkEntitySlices.java
@@ -116,8 +116,19 @@ 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
         try (final ProblemReporter.ScopedCollector scopedCollector = new ProblemReporter.ScopedCollector(ChunkAccess.problemPath(chunkPos), LOGGER)) {
             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
                 final TagValueOutput savedEntity = TagValueOutput.createWithContext(
                     scopedCollector.forChild(entity.problemPath()), entity.registryAccess()
                 );
diff --git a/net/minecraft/world/entity/EntityType.java b/net/minecraft/world/entity/EntityType.java
index 98586dfc562cf6909df0f4bfa1c19e35b3172abe..f92adee1c187561d3790a5a5c8c81f5e1543ed97 100644
--- a/net/minecraft/world/entity/EntityType.java
+++ b/net/minecraft/world/entity/EntityType.java
@@ -1448,7 +1448,18 @@ public class EntityType<T extends Entity> implements FeatureElement, EntityTypeT
     }
 
     public static Stream<Entity> loadEntitiesRecursive(ValueInput.ValueInputList input, Level level, EntitySpawnReason spawnReason) {
+        final java.util.Map<EntityType<?>, Integer> loadedEntityCounts = new java.util.HashMap<>(); // Paper - Entity load/save limit per chunk
         return input.stream().mapMulti((valueInput, consumer) -> loadEntityRecursive(valueInput, 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 (loadedEntityCounts.getOrDefault(entityType, 0) >= saveLimit) {
+                    return null;
+                }
+                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 bf45cce4db77966d44d7a8d97673bb6631a6adaf..f1f8575a4b37114ced3cdb1d2ea33a36a2db44fd 100644
--- a/net/minecraft/world/level/chunk/storage/EntityStorage.java
+++ b/net/minecraft/world/level/chunk/storage/EntityStorage.java
@@ -95,7 +95,18 @@ public class EntityStorage implements EntityPersistentStorage<Entity> {
         } else {
             try (ProblemReporter.ScopedCollector scopedCollector = new ProblemReporter.ScopedCollector(ChunkAccess.problemPath(pos), LOGGER)) {
                 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
                     TagValueOutput tagValueOutput = TagValueOutput.createWithContext(scopedCollector.forChild(entity.problemPath()), entity.registryAccess());
                     if (entity.save(tagValueOutput)) {
                         CompoundTag compoundTag1 = tagValueOutput.buildResult();