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 847fd720f11e89d906430c820bc92afe0454761d..b1b26e7c0f66f0697bcfe9eb045d45f31cd9ab06 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -404,6 +404,7 @@ 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 237025be183b3cc93920430075edcc0bb2899b68..f2f8fbc8a8cf32bcba0ad7ac9b6cdd75468e062a 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3642,10 +3642,12 @@ 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);
                 }
             }