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 2fcdd61e9669904756aa33b1ff8ab7160ea5e371..660a210c363fcb42145b273ea6b977ce4844505d 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -395,6 +395,7 @@ 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 3cb452003cffd02a1ef88b0cb512a5c66d4e078b..eafbe6fd829c2067b1e81ea8aad77fe3ba3df82f 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3454,10 +3454,12 @@ 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);
                 }
             }