From 658642250d0d7fadf44d95ff1f41a4d36b69eaa5 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 f65a3fe8..0ea2a856 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -413,4 +413,10 @@ public class PaperWorldConfig {
     private void armorStandEntityLookups() {
         armorStandEntityLookups = getBoolean("armor-stands-do-collision-entity-lookups", true);
     }
+
+    public int maxCollisionsPerEntity;
+    private void maxEntityCollision() {
+        maxCollisionsPerEntity = getInt( "max-entity-collisions", this.spigotConfig.getInt("max-entity-collisions", 8) );
+        log( "Max Entity Collisions: " + maxCollisionsPerEntity );
+    }
 }
diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index 3f1c78af..04bc05d3 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -170,6 +170,7 @@ public abstract class Entity implements ICommandListener {
     public final boolean defaultActivationState;
     public long activatedTick = Integer.MIN_VALUE;
     public boolean fromMobSpawner;
+    protected int numCollisions = 0; // Paper
     public void inactiveTick() { }
     // Spigot end
 
diff --git a/src/main/java/net/minecraft/server/EntityLiving.java b/src/main/java/net/minecraft/server/EntityLiving.java
index 38c04337..c97ee68a 100644
--- a/src/main/java/net/minecraft/server/EntityLiving.java
+++ b/src/main/java/net/minecraft/server/EntityLiving.java
@@ -2191,8 +2191,11 @@ public abstract class EntityLiving extends Entity {
                 }
             }
 
-            for (j = 0; j < list.size(); ++j) {
+            numCollisions = Math.max(0, numCollisions - world.paperConfig.maxCollisionsPerEntity); // Paper
+            for (j = 0; j < list.size() && numCollisions < world.paperConfig.maxCollisionsPerEntity; ++j) { // Paper
                 Entity entity = (Entity) list.get(j);
+                entity.numCollisions++; // Paper
+                numCollisions++; // Paper
 
                 this.C(entity);
             }
-- 
2.17.0