From c47b48aa35d881755ab882724c0b166cb2085e6b Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Tue, 13 Nov 2018 14:01:00 +0000
Subject: [PATCH] limit the range at which we'll consider an attackable target

This patch aims to ensure that MCP World#getNearestAttackablePlayer
will not trigger chunk loads due to PathfinderGoalNearestAttackableTarget
performing a ray trace operation by pre-checking the maximum limit;

Given that the implementation shows that the limit should only ever
decrease when set, allowing us to skip further checks earlier on
when looking for an attackable entity

diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index 05256ad3c..747fda044 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -2793,8 +2793,13 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc
         for (int i = 0; i < this.players.size(); ++i) {
             EntityHuman entityhuman1 = (EntityHuman) this.players.get(i);
 
+            // Paper start
+            // move distance check up, if set, check distance^2 is less than XZlimit^2, continue
+            // 4th method param is XZlimit (at least at the time of commit)
+            double d6 = entityhuman1.d(d0, entityhuman1.locY, d2);
+            if (d3 < 0.0D || d6 < d3 * d3)
             if (!entityhuman1.abilities.isInvulnerable && entityhuman1.isAlive() && !entityhuman1.isSpectator() && (predicate == null || predicate.test(entityhuman1))) {
-                double d6 = entityhuman1.d(d0, entityhuman1.locY, d2);
+                // Paper end
                 double d7 = d3;
 
                 if (entityhuman1.isSneaking()) {
-- 
2.20.0