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 8451982ba4fc9522f2d77f68fc63a0e12558955f..ee8ce0e5bdb0acb7d6ef3439a388e108ea1807de 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -391,4 +391,10 @@ public class PaperWorldConfig {
         treasureMapsAlreadyDiscoveredVillager = getBoolean("treasure-maps-find-already-discovered.villager-trade", treasureMapsAlreadyDiscoveredVillager);
         treasureMapsAlreadyDiscoveredLootTable = getBooleanOrNull("treasure-maps-find-already-discovered.loot-tables", treasureMapsAlreadyDiscoveredLootTable);
     }
+
+    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 63a6ac09569729d8f9810f339db76d55b1440a0f..8af99a4b7a1e834782dd7dd9ca53263f9e90e6d0 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -338,6 +338,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
     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 8e6c9fb5eb58c20b97141551b2514c004eb4cedb..2eed84529ad9a34ae88c4f37f2b0c7943f51b0ad 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3261,8 +3261,11 @@ 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);
             }