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 bd17157631a74f80e3b5ce50bb1f681abe1dd6a7..46a21ed2408a42aafd16647e17e556730e799cbd 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -401,6 +401,7 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
     public long activatedTick = Integer.MIN_VALUE;
     public void inactiveTick() { }
     // Spigot end
+    protected int numCollisions = 0; // Paper - Cap entity collisions
     // Paper start - Entity origin API
     @javax.annotation.Nullable
     private org.bukkit.util.Vector origin;
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index cacada8cfbe171cdb10aa2a78483ef3b613b414a..51dadc6d3ea7f0b7b5eb5117b58df0e532c65eb9 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3474,10 +3474,12 @@ 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 - Cap entity collisions
 
-                while (iterator1.hasNext()) {
+                while (iterator1.hasNext() && this.numCollisions < this.level().paperConfig().collisions.maxEntityCollisions) { // Paper - Cap entity collisions
                     Entity entity1 = (Entity) iterator1.next();
-
+                    entity1.numCollisions++; // Paper - Cap entity collisions
+                    this.numCollisions++; // Paper - Cap entity collisions
                     this.doPush(entity1);
                 }
             }
