From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Fri, 19 Feb 2021 22:51:52 -0800
Subject: [PATCH] Oprimise map impl for tracked players

Reference2BooleanOpenHashMap is going to have
better lookups than HashMap.

diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index 03b802f9f6e31b1ab23af0ff7b235f64c72ec462..84dfa7efa4be86558c38ee9e6f70f87b5638173a 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -1343,7 +1343,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
         final Entity entity;
         private final int range;
         SectionPos lastSectionPos;
-        public final Set<ServerPlayerConnection> seenBy = Sets.newIdentityHashSet();
+        public final Set<ServerPlayerConnection> seenBy = new ReferenceOpenHashSet<>(); // Paper - optimise map impl
 
         public TrackedEntity(Entity entity, int i, int j, boolean flag) {
             this.serverEntity = new ServerEntity(ChunkMap.this.level, entity, j, flag, this::broadcast, this.seenBy); // CraftBukkit