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 edbfc7bc783833a62542a4515dde13034ae29c10..515d0f3a7ea6f19ce8f1cb16d798d898894be445 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -394,6 +394,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
     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 77a4122cf5a11b29b14a7fc4ac6420ccea49af1b..202e3b66a81de2f76d5a8bba3538f1554b8debf3 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3348,10 +3348,12 @@ public abstract class LivingEntity extends Entity implements Attackable {
                 }
 
                 Iterator iterator1 = list.iterator();
+                this.numCollisions = Math.max(0, this.numCollisions - this.level().paperConfig().collisions.maxEntityCollisions); // Paper
 
-                while (iterator1.hasNext()) {
+                while (iterator1.hasNext() && this.numCollisions < this.level().paperConfig().collisions.maxEntityCollisions) { // Paper
                     Entity entity1 = (Entity) iterator1.next();
-
+                    entity1.numCollisions++; // Paper
+                    this.numCollisions++; // Paper
                     this.doPush(entity1);
                 }
             }