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 a28aa788f46dc944e174957fbed23dfeeff1eb72..760596375e26b4cd73cc378758f4bf761c3352a5 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 728370332d284fbe95fed57f4e5a88cabbe3f146..b6aaebb5359c8162359b377b3485c3fcf91587e1 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3313,8 +3313,11 @@ 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);
                 }