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/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index f383f30b9dd1a7c6cf69d342f99118beec70b206..47b717e8741bb2b8f3aa776dcdc73a3e7dbb5960 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -370,4 +370,10 @@ public class PaperWorldConfig {
             log("Treasure Maps will return already discovered locations");
         }
     }
+
+    public int maxCollisionsPerEntity = 8;
+    private void maxEntityCollision() {
+        maxCollisionsPerEntity = getInt( "max-entity-collisions", this.spigotConfig.getInt("max-entity-collisions", this.maxCollisionsPerEntity, false) );
+        log( "Max Entity Collisions: " + maxCollisionsPerEntity );
+    }
 }
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index b1d86df7002d6f6398288bc24c0d92a6349e0dcb..d6e1860772724347d62fb6990304ec8f4cde4035 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -308,6 +308,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, i
     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 36aef3dbfe407ca6fa206bc3fc4390e5c2770aa3..e0fe53045da81fc9b2eac3b215d641cf0c722895 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3227,8 +3227,11 @@ public abstract class LivingEntity extends Entity {
                 }
             }
 
-            for (j = 0; j < list.size(); ++j) {
+            this.numCollisions = Math.max(0, this.numCollisions - this.level.paperConfig.maxCollisionsPerEntity); // Paper
+            for (j = 0; j < list.size() && this.numCollisions < this.level.paperConfig.maxCollisionsPerEntity; ++j) { // Paper
                 Entity entity = (Entity) list.get(j);
+                entity.numCollisions++; // Paper
+                this.numCollisions++; // Paper
 
                 this.doPush(entity);
             }