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/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 86fa079f9f1f958ed586c966467d26a44e09b11c..58256b341aa15e946abef464453c0ffcaf55b372 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -379,6 +379,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
     public void inactiveTick() { }
     // Spigot end
     // Paper start
+    protected int numCollisions = 0; // Paper
     @javax.annotation.Nullable
     private org.bukkit.util.Vector origin;
     @javax.annotation.Nullable
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index a42983b4d7dbd360bbe4206dcf6aa95375ef9b2b..6295c89211ba86c10009775f4d399f597d240fd0 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3289,8 +3289,11 @@ public abstract class LivingEntity extends Entity {
                 }
             }
 
-            for (j = 0; j < list.size(); ++j) {
+            this.numCollisions = Math.max(0, this.numCollisions - this.level.paperConfig().collisions.maxEntityCollisions); // Paper
+            for (j = 0; j < list.size() && this.numCollisions < this.level.paperConfig().collisions.maxEntityCollisions; ++j) { // Paper
                 Entity entity = (Entity) list.get(j);
+                entity.numCollisions++; // Paper
+                this.numCollisions++; // Paper
 
                 this.doPush(entity);
             }