From be6fe9effd62617726e175f8bfd2227a83c2a59a Mon Sep 17 00:00:00 2001
From: Ammar Askar <ammar@ammaraskar.com>
Date: Tue, 16 Jul 2013 03:32:32 +0500
Subject: [PATCH] Entity ticking chunk caching

Cache known loaded chunks so we avoid making a potentially expensive contains call for every single entity in exchange for some simple arithmetic. Best case scenario, this cuts down contains call to once per chunk, worst case it adds on some simple arithmetic operations

diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index 0b6b681..13ca7fa 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1179,6 +1179,7 @@ public abstract class World implements IBlockAccess {
         CrashReport crashreport;
         CrashReportSystemDetails crashreportsystemdetails;
 
+        long lastChunk = Long.MIN_VALUE; // Spigot - cache chunk x, z cords for unload queue
         for (i = 0; i < this.i.size(); ++i) {
             entity = (Entity) this.i.get(i);
             // CraftBukkit start - Fixed an NPE, don't process entities in chunks queued for unload
@@ -1187,10 +1188,15 @@ public abstract class World implements IBlockAccess {
             }
 
             ChunkProviderServer chunkProviderServer = ((WorldServer) this).chunkProviderServer;
-            if (chunkProviderServer.unloadQueue.contains(MathHelper.floor(entity.locX) >> 4, MathHelper.floor(entity.locZ) >> 4)) {
-                continue;
+            // Spigot start - check last chunk to see if this loaded (fast cache)
+            long chunk = org.bukkit.craftbukkit.util.LongHash.toLong(MathHelper.floor(entity.locX) >> 4, MathHelper.floor(entity.locZ) >> 4);
+            if (lastChunk != chunk) {
+                if (chunkProviderServer.unloadQueue.contains(chunk)) { // Spigot end
+                    continue;
+                }
             }
             // CraftBukkit end
+            lastChunk = chunk; // Spigot
 
             try {
                 ++entity.ticksLived;
@@ -1211,6 +1217,7 @@ public abstract class World implements IBlockAccess {
                 this.i.remove(i--);
             }
         }
+        lastChunk = Long.MIN_VALUE; // Spigot
 
         this.methodProfiler.c("remove");
         this.entityList.removeAll(this.f);
@@ -1241,10 +1248,15 @@ public abstract class World implements IBlockAccess {
 
             // CraftBukkit start - Don't tick entities in chunks queued for unload
             ChunkProviderServer chunkProviderServer = ((WorldServer) this).chunkProviderServer;
-            if (chunkProviderServer.unloadQueue.contains(MathHelper.floor(entity.locX) >> 4, MathHelper.floor(entity.locZ) >> 4)) {
-                continue;
+            // Spigot start - check last chunk to see if this loaded (fast cache)
+            long chunk = org.bukkit.craftbukkit.util.LongHash.toLong(MathHelper.floor(entity.locX) >> 4, MathHelper.floor(entity.locZ) >> 4);
+            if (lastChunk != chunk) {
+                if (chunkProviderServer.unloadQueue.contains(chunk)) { // Spigot end
+                    continue;
+                }
             }
             // CraftBukkit end
+            lastChunk = Long.MIN_VALUE; // Spigot
 
             if (entity.vehicle != null) {
                 if (!entity.vehicle.dead && entity.vehicle.passenger == entity) {
-- 
1.8.3.2