From 41f9dc9bb456883704e43cac171bc45c1f2fa637 Mon Sep 17 00:00:00 2001
From: jmp <jasonpenilla2@me.com>
Date: Wed, 18 Nov 2020 20:52:25 -0800
Subject: [PATCH] PaperPR - Projectile load/save limit per chunk

Adds a config option to limit the number of projectiles saved and loaded
to a chunk. Limits are counted per entity type, i.e. a limit of 5 means
that 5 arrows, 5 snowballs, 5 tridents, etc. will be allowed to be
saved/loaded per chunk. The default value of -1 disables the limit.

diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index ae5ed3bd0b663092a4658b24cbd69d37b4e141cb..2452f54d96cab2d93140c64e25d9b799cbc94caa 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -709,4 +709,9 @@ public class PaperWorldConfig {
     private void fixCuringExploit() {
         fixCuringZombieVillagerDiscountExploit = getBoolean("game-mechanics.fix-curing-zombie-villager-discount-exploit", fixCuringZombieVillagerDiscountExploit);
     }
+
+    public int projectileSaveLimit = -1;
+    private void projectileSaveLimit() {
+        projectileSaveLimit = getInt("projectile-load-save-per-chunk-limit", projectileSaveLimit);
+    }
 }
diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
index 64dd95292fb4d058f6200bfcadaedfbd62b2461d..3628b04fc4f4f4663b3780eadac6ff9e430e4900 100644
--- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
+++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
@@ -525,11 +525,21 @@ public class ChunkRegionLoader {
 
             chunk.d(false);
 
+            // Paper start
+            final Map<EntityTypes<?>, Integer> savedProjectileCounts = Maps.newHashMap();
             for (int j = 0; j < chunk.getEntitySlices().length; ++j) {
                 Iterator iterator1 = chunk.getEntitySlices()[j].iterator();
 
                 while (iterator1.hasNext()) {
                     Entity entity = (Entity) iterator1.next();
+                    if (worldserver.paperConfig.projectileSaveLimit > -1 && (entity instanceof IProjectile || entity instanceof EntityEnderSignal)) {
+                        final EntityTypes<?> projectileType = entity.getEntityType();
+                        if (savedProjectileCounts.getOrDefault(projectileType, 0) >= worldserver.paperConfig.projectileSaveLimit) {
+                            continue;
+                        }
+                        savedProjectileCounts.merge(projectileType, 1, Integer::sum);
+                    }
+                    // Paper end
                     NBTTagCompound nbttagcompound4 = new NBTTagCompound();
                     // Paper start
                     if (asyncsavedata == null && !entity.dead && (int) Math.floor(entity.locX()) >> 4 != chunk.getPos().x || (int) Math.floor(entity.locZ()) >> 4 != chunk.getPos().z) {
@@ -660,10 +670,20 @@ public class ChunkRegionLoader {
         NBTTagList nbttaglist = nbttagcompound.getList("Entities", 10);
         World world = chunk.getWorld();
 
+        // Paper start
+        final Map<EntityTypes<?>, Integer> loadedProjectileCounts = Maps.newHashMap();
         for (int i = 0; i < nbttaglist.size(); ++i) {
             NBTTagCompound nbttagcompound1 = nbttaglist.getCompound(i);
 
             EntityTypes.a(nbttagcompound1, world, (entity) -> {
+                if (world.paperConfig.projectileSaveLimit > -1 && (entity instanceof IProjectile || entity instanceof EntityEnderSignal)) {
+                    final EntityTypes<?> projectileType = entity.getEntityType();
+                    if (loadedProjectileCounts.getOrDefault(projectileType, 0) >= world.paperConfig.projectileSaveLimit) {
+                        return entity;
+                    }
+                    loadedProjectileCounts.merge(projectileType, 1, Integer::sum);
+                }
+                // Paper end
                 chunk.a(entity);
                 return entity;
             });