From 9c96f51c8068de370baeb9fa4aee91c82d273e42 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 7 Mar 2016 22:43:26 -0500
Subject: [PATCH] Optimize NavigationListener Iteration

I don't know what the person who wrote that code was smoking, but I
don't think it was good.

Gets rid of the WeakHashMap that mojang was abusing purely to be lazy
on clean up, and handles registering and deregistering navigation
upon world add/remove operations.

diff --git a/src/main/java/net/minecraft/server/NavigationAbstract.java b/src/main/java/net/minecraft/server/NavigationAbstract.java
index 7d794b9..ca4cb26 100644
--- a/src/main/java/net/minecraft/server/NavigationAbstract.java
+++ b/src/main/java/net/minecraft/server/NavigationAbstract.java
@@ -32,7 +32,7 @@ public abstract class NavigationAbstract {
         this.b = world;
         this.g = entityinsentient.getAttributeInstance(GenericAttributes.FOLLOW_RANGE);
         this.s = this.a();
-        this.b.C().a(this);
+        //this.b.C().a(this); // Paper
     }
 
     protected abstract Pathfinder a();
diff --git a/src/main/java/net/minecraft/server/NavigationListener.java b/src/main/java/net/minecraft/server/NavigationListener.java
index f82ea80..ef446fc 100644
--- a/src/main/java/net/minecraft/server/NavigationListener.java
+++ b/src/main/java/net/minecraft/server/NavigationListener.java
@@ -1,26 +1,41 @@
 package net.minecraft.server;
 
+import java.util.ArrayList; // Paper
+import java.util.List; // Paper
 import java.util.WeakHashMap;
 
 public class NavigationListener implements IWorldAccess {
 
     private static final Object a = new Object();
-    private final WeakHashMap<NavigationAbstract, Object> b = new WeakHashMap();
+    private final List<NavigationAbstract> navigators = new ArrayList<>(); // Paper
 
     public NavigationListener() {}
 
+
     public void a(NavigationAbstract navigationabstract) {
-        this.b.put(navigationabstract, NavigationListener.a);
+        this.add(navigationabstract); // Paper
     }
 
+    // Paper start
+    public void add(NavigationAbstract navigationabstract) {
+        this.navigators.add(navigationabstract);
+    }
+    public void remove(NavigationAbstract navigationabstract) {
+        this.navigators.remove(navigationabstract);
+    }
+    // Paper end
+
     public void a(World world, BlockPosition blockposition, IBlockData iblockdata, IBlockData iblockdata1, int i) {
         if (this.a(world, blockposition, iblockdata, iblockdata1)) {
-            NavigationAbstract[] anavigationabstract = (NavigationAbstract[]) this.b.keySet().toArray(new NavigationAbstract[0]);
-            NavigationAbstract[] anavigationabstract1 = anavigationabstract;
-            int j = anavigationabstract.length;
+            // Paper start
+            //NavigationAbstract[] anavigationabstract = (NavigationAbstract[]) this.navigators.keySet().toArray(new NavigationAbstract[0]);
+            //NavigationAbstract[] anavigationabstract1 = anavigationabstract;
+            int j = this.navigators.size();
+
 
             for (int k = 0; k < j; ++k) {
-                NavigationAbstract navigationabstract = anavigationabstract1[k];
+                NavigationAbstract navigationabstract = this.navigators.get(k);
+                // Paper end
 
                 if (navigationabstract != null && !navigationabstract.i()) {
                     PathEntity pathentity = navigationabstract.k();
diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index cae2873..5ae2f14 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1024,6 +1024,7 @@ public abstract class World implements IBlockAccess {
             this.getChunkAt(i, j).a(entity);
             this.entityList.add(entity);
             this.b(entity);
+            if (entity instanceof EntityInsentient) { this.getNavListener().add(((EntityInsentient) entity).navigation); } // Paper
             return true;
         }
     }
@@ -1105,6 +1106,7 @@ public abstract class World implements IBlockAccess {
         }
         // CraftBukkit end
         } // Spigot
+        if (entity instanceof EntityInsentient) { this.getNavListener().remove(((EntityInsentient) entity).navigation); } // Paper
         this.c(entity);
     }
 
-- 
2.7.2