From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 22 Jan 2017 18:07:56 -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

This is not tied to the maxEntityCramming rule. Cramming will still apply
just as it does in Vanilla, but entity pushing logic will be capped.

You can set this to 0 to disable collisions.

diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index 255b4081314162cbe344b008158c6f4584795fb8..04ee0856a8c62e1afb438d4fddf40e605e82a074 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -317,4 +317,10 @@ public class PaperWorldConfig {
             log("Treasure Maps will return already discovered locations");
         }
     }
+
+    public int maxCollisionsPerEntity;
+    private void maxEntityCollision() {
+        maxCollisionsPerEntity = getInt( "max-entity-collisions", this.spigotConfig.getInt("max-entity-collisions", 8) );
+        log( "Max Entity Collisions: " + maxCollisionsPerEntity );
+    }
 }
diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index 62f1da9addcfb30ab23dce8c755dcc3e9951e202..8933a974da42a06cb0b382e3436d4bb077da0c27 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -182,6 +182,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     public final org.spigotmc.ActivationRange.ActivationType activationType = org.spigotmc.ActivationRange.initializeEntityActivationType(this);
     public final boolean defaultActivationState;
     public long activatedTick = Integer.MIN_VALUE;
+    protected int numCollisions = 0; // Paper
     public void inactiveTick() { }
     // Spigot end
 
diff --git a/src/main/java/net/minecraft/server/EntityLiving.java b/src/main/java/net/minecraft/server/EntityLiving.java
index f62653d5507a1f62e0521dc901283c2735b14e91..60ee57139a86492c290b33808ca35300dcf96f54 100644
--- a/src/main/java/net/minecraft/server/EntityLiving.java
+++ b/src/main/java/net/minecraft/server/EntityLiving.java
@@ -2791,8 +2791,11 @@ public abstract class EntityLiving extends Entity {
                 }
             }
 
-            for (j = 0; j < list.size(); ++j) {
+            numCollisions = Math.max(0, numCollisions - world.paperConfig.maxCollisionsPerEntity); // Paper
+            for (j = 0; j < list.size() && numCollisions < world.paperConfig.maxCollisionsPerEntity; ++j) { // Paper
                 Entity entity = (Entity) list.get(j);
+                entity.numCollisions++; // Paper
+                numCollisions++; // Paper
 
                 this.C(entity);
             }