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 2dc58b9f769ea43b737804456aafab47ecc143b8..c611b5a63498f5ad1f50a75ccd5d7299e27df7e3 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -324,4 +324,10 @@ public class PaperWorldConfig {
             log("Treasure Maps will return already discovered locations");
         }
     }
+
+    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/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 49da1525cfc46743013bbac0528ec58501cab6eb..b798190628c1d83b5bf9e5497b515ef1e9f26707 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -268,6 +268,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, ne
     public final org.spigotmc.ActivationRange.ActivationType activationType = org.spigotmc.ActivationRange.initializeEntityActivationType(this);
     public final boolean defaultActivationState;
     public long activatedTick = Integer.MIN_VALUE;
+    protected int numCollisions = 0; // Paper
     public void inactiveTick() { }
     // Spigot end
 
diff --git a/src/main/java/net/minecraft/world/entity/EntityLiving.java b/src/main/java/net/minecraft/world/entity/EntityLiving.java
index 6fa269cec002fcffd6d02125c20efa9314148243..2eee92f74a7c82ec7df05db6df79743b4345cc86 100644
--- a/src/main/java/net/minecraft/world/entity/EntityLiving.java
+++ b/src/main/java/net/minecraft/world/entity/EntityLiving.java
@@ -2903,8 +2903,11 @@ 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);
             }