From 1915a0c2ebe060013bf7688a5e47bdbfd15a40a9 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Fri, 31 Jan 2014 11:18:34 -0500
Subject: [PATCH] Cap Entity Collisions

Limit a single entity to colliding a max of configurable times per tick.
This will alleviate issues where living entities are hoarded in 1x1 pens.

diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index 875dbb9..4427af9 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -149,6 +149,7 @@ public abstract class Entity implements ICommandListener {
     public long activatedTick = Integer.MIN_VALUE;
     public boolean fromMobSpawner;
     public void inactiveTick() { }
+    protected int numCollisions = 0;
     // Spigot end
 
     public Entity(World world) {
diff --git a/src/main/java/net/minecraft/server/EntityLiving.java b/src/main/java/net/minecraft/server/EntityLiving.java
index 7e6a83c..365b61d 100644
--- a/src/main/java/net/minecraft/server/EntityLiving.java
+++ b/src/main/java/net/minecraft/server/EntityLiving.java
@@ -2026,9 +2026,14 @@ public abstract class EntityLiving extends Entity {
         List list = this.world.getEntities(this, this.getBoundingBox(), IEntitySelector.a(this));
 
         if (!list.isEmpty()) {
-            for (int i = 0; i < list.size(); ++i) {
+                numCollisions = Math.max(0, numCollisions - world.spigotConfig.maxCollisionsPerEntity); // Spigot
+                for (int i = 0; i < list.size() && numCollisions < world.spigotConfig.maxCollisionsPerEntity; ++i) {
                 Entity entity = (Entity) list.get(i);
 
+                // Spigot start
+                entity.numCollisions++;
+                numCollisions++;
+                // Spigot end
                 this.C(entity);
             }
         }
diff --git a/src/main/java/org/spigotmc/SpigotWorldConfig.java b/src/main/java/org/spigotmc/SpigotWorldConfig.java
index 0c7d958..f1245cf 100644
--- a/src/main/java/org/spigotmc/SpigotWorldConfig.java
+++ b/src/main/java/org/spigotmc/SpigotWorldConfig.java
@@ -228,4 +228,11 @@ public class SpigotWorldConfig
         enableZombiePigmenPortalSpawns = getBoolean( "enable-zombie-pigmen-portal-spawns", true );
         log( "Allow Zombie Pigmen to spawn from portal blocks: " + enableZombiePigmenPortalSpawns );
     }
+
+    public int maxCollisionsPerEntity;
+    private void maxEntityCollision()
+    {
+        maxCollisionsPerEntity = getInt( "max-entity-collisions", 8 );
+        log( "Max Entity Collisions: " + maxCollisionsPerEntity );
+    }
 }
-- 
2.7.4