From 7ec6ae32dc53d6401706f46533d05f47cb554b30 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 30 Mar 2016 02:13:24 -0400
Subject: [PATCH] Use Optimized Collections

Swap out CraftBukkit LongObjectHashMap with Long2ObjectOpenHashMap
Swap out Integer key HashMap for a Int2ObjectOpenHashMap For ChunkProviderServer

Amaranth, the creator of LongObjectHashMap, tested it vs fastutil and determined fastutil to be 3x faster
and could not create anything faster than fastutil.

These collections are super fast as seen
http://java-performance.info/hashmap-overview-jdk-fastutil-goldman-sachs-hppc-koloboke-trove-january-2015/

diff --git a/src/main/java/net/minecraft/server/DataWatcher.java b/src/main/java/net/minecraft/server/DataWatcher.java
index 79a240cd1..6c259effb 100644
--- a/src/main/java/net/minecraft/server/DataWatcher.java
+++ b/src/main/java/net/minecraft/server/DataWatcher.java
@@ -12,6 +12,7 @@ import java.util.Map;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 import javax.annotation.Nullable;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap; // Paper
 import org.apache.commons.lang3.ObjectUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -21,7 +22,7 @@ public class DataWatcher {
     private static final Logger LOGGER = LogManager.getLogger();
     private static final Map<Class<? extends Entity>, Integer> b = Maps.newHashMap();
     private final Entity c;
-    private final Map<Integer, DataWatcher.Item<?>> d = Maps.newHashMap();
+    private final Map<Integer, DataWatcher.Item<?>> d = new Int2ObjectOpenHashMap<>(); // Paper
     private final ReadWriteLock e = new ReentrantReadWriteLock();
     private boolean f = true;
     private boolean g;
-- 
2.21.0