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 293f6c0be399419560f45bf6c834220f123b3c24..875516b17452968e53efda9d777676ec4bee0f79 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -387,6 +387,7 @@ 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 565d0349328b7ae5fcbdf1682dcedff937457f92..e173f7f020bc25ba68bc5c4e82cbcb7abd6c7d75 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3327,8 +3327,11 @@ public abstract class LivingEntity extends Entity implements Attackable {
                     }
                 }
 
-                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);
                 }