From b8003723a21e465327a9ba3d99bcf3b57daa0a51 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 eb552e2..5702cb0 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -147,6 +147,7 @@ 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 b78b273..f0921e8 100644
--- a/src/main/java/net/minecraft/server/EntityLiving.java
+++ b/src/main/java/net/minecraft/server/EntityLiving.java
@@ -1967,7 +1967,8 @@ public abstract class EntityLiving extends Entity {
         List list = this.world.a((Entity) this, this.getBoundingBox(), IEntitySelector.a(this));
 
         if (this.isInteractable() && !list.isEmpty()) { // Spigot: Add isInteractable() condition
-            for (int i = 0; i < list.size(); ++i) {
+                numCollisions -= world.spigotConfig.maxCollisionsPerEntity; // Spigot
+                for (int i = 0; i < list.size() && numCollisions < world.spigotConfig.maxCollisionsPerEntity; ++i) {
                 Entity entity = (Entity) list.get(i);
                 // TODO better check now?
                 // CraftBukkit start - Only handle mob (non-player) collisions every other tick
@@ -1976,7 +1977,8 @@ public abstract class EntityLiving extends Entity {
                 }
                 // CraftBukkit end
 
-
+                entity.numCollisions++; // Spigot
+                numCollisions++; // Spigot
                 this.C(entity);
             }
         }
diff --git a/src/main/java/org/spigotmc/SpigotWorldConfig.java b/src/main/java/org/spigotmc/SpigotWorldConfig.java
index 4cca76a..19525eb 100644
--- a/src/main/java/org/spigotmc/SpigotWorldConfig.java
+++ b/src/main/java/org/spigotmc/SpigotWorldConfig.java
@@ -224,4 +224,11 @@ 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 );
+    }
 }
-- 
2.5.0