From c12c8e716ed41b8cee8d9f1057d1e138b73d7169 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 30 Mar 2016 02:13:24 -0400
Subject: [PATCH] Use FastUtil Long/Int HashMap's

For DataWatcher, swap out plain Integer key HashMap for a Int2ObjectOpenHashMap
For ChunkProviderServer, swap out CB's custom LongHashMap with Long2ObjectOpenHashMap

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/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
index f31ffe2..646197c 100644
--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
+++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -5,6 +5,7 @@ import java.util.Iterator;
 import java.util.List;
 
 import com.destroystokyo.paper.exception.ServerInternalException;
+import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap; // Paper
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -26,7 +27,7 @@ public class ChunkProviderServer implements IChunkProvider {
     private final IChunkLoader chunkLoader;
     // Paper start
     protected Chunk lastChunkByPos = null;
-    public LongObjectHashMap<Chunk> chunks = new LongObjectHashMap<Chunk>() {
+    public Long2ObjectOpenHashMap<Chunk> chunks = new Long2ObjectOpenHashMap<Chunk>() {
         @Override
         public Chunk get(long key) {
             if (lastChunkByPos != null && key == lastChunkByPos.chunkKey) {
diff --git a/src/main/java/net/minecraft/server/DataWatcher.java b/src/main/java/net/minecraft/server/DataWatcher.java
index f1c62ec..deb9643 100644
--- a/src/main/java/net/minecraft/server/DataWatcher.java
+++ b/src/main/java/net/minecraft/server/DataWatcher.java
@@ -11,13 +11,15 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap; // Paper
 import org.apache.commons.lang3.ObjectUtils;
 
 public class DataWatcher {
 
     private static final Map<Class<? extends Entity>, Integer> a = Maps.newHashMap();
     private final Entity b;
-    private final Map<Integer, DataWatcher.Item<?>> c = Maps.newHashMap();
+    private final Map<Integer, DataWatcher.Item<?>> c = new Int2ObjectOpenHashMap<>(); // Paper
     private final ReadWriteLock d = new ReentrantReadWriteLock();
     private boolean e = true;
     private boolean f;
-- 
2.8.0