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 800191e9ed63773333b5650d8ffcb14ffc8ec338..9ab37d95b0dbd13dfe31b34b2a91c2a7bc7f6e64 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -108,6 +108,7 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.bukkit.entity.Player;
 // CraftBukkit end
+import it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet; // Paper
 
 public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider {
 
@@ -2141,7 +2142,7 @@ 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
