From db76c53f063cc8a9ba146d427bf2ee9562f48015 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 69331ff..4d09fdb 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -1021,6 +1021,7 @@ public abstract class Entity {
 
     public void b_(EntityHuman entityhuman) {}
 
+    int numCollisions = 0; // Spigot
     public void collide(Entity entity) {
         if (entity.passenger != this && entity.vehicle != this) {
             double d0 = entity.locX - this.locX;
diff --git a/src/main/java/net/minecraft/server/EntityLiving.java b/src/main/java/net/minecraft/server/EntityLiving.java
index 35b2f75..ab28bd3 100644
--- a/src/main/java/net/minecraft/server/EntityLiving.java
+++ b/src/main/java/net/minecraft/server/EntityLiving.java
@@ -1486,7 +1486,9 @@ public abstract class EntityLiving extends Entity {
         List list = this.world.getEntities(this, this.boundingBox.grow(0.20000000298023224D, 0.0D, 0.20000000298023224D));
 
         if (this.R() && list != null && !list.isEmpty()) { // Spigot: Add this.R() condition
+            numCollisions -= world.spigotConfig.maxCollisionsPerEntity; // Spigot
             for (int i = 0; i < list.size(); ++i) {
+                if (numCollisions > world.spigotConfig.maxCollisionsPerEntity) { break; } // Spigot
                 Entity entity = (Entity) list.get(i);
 
                 // TODO better check now?
@@ -1497,9 +1499,12 @@ public abstract class EntityLiving extends Entity {
                 // CraftBukkit end
 
                 if (entity.S()) {
+                    entity.numCollisions++; // Spigot
+                    numCollisions++; // Spigot
                     this.n(entity);
                 }
             }
+            numCollisions = 0; // Spigot
         }
     }
 
diff --git a/src/main/java/org/spigotmc/SpigotWorldConfig.java b/src/main/java/org/spigotmc/SpigotWorldConfig.java
index 4cff009..979b315 100644
--- a/src/main/java/org/spigotmc/SpigotWorldConfig.java
+++ b/src/main/java/org/spigotmc/SpigotWorldConfig.java
@@ -271,4 +271,11 @@ public class SpigotWorldConfig
         maxBulkChunk = getInt( "max-bulk-chunks", 5 );
         log( "Sending up to " + maxBulkChunk + " chunks per packet" );
     }
+
+    public int maxCollisionsPerEntity;
+    private void maxEntityCollision()
+    {
+        maxCollisionsPerEntity = getInt( "max-entity-collisions", 8 );
+        log( "Max Entity Collisions: " + maxCollisionsPerEntity );
+    }
 }
-- 
1.8.3.2