From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MrPowerGamerBR <git@mrpowergamerbr.com>
Date: Thu, 23 Nov 2023 14:36:47 -0300
Subject: [PATCH] SparklyPaper: Optimize "canSee" checks

Original project: https://github.com/SparklyPower/SparklyPaper

The "canSee" checks is in a hot path, invoked by each entity for each player on the server if they are in tracking range, so optimizing it is pretty nice

First, we change the original "HashMap" to fastutil's "Object2ObjectOpenHashMap", because the containsKey throughput is better

Then, we add a "isEmpty()" check before attempting to check if the map contains something

This seems stupid, but it does seem that it improves the performance a bit, and it makes sense, "containsKey(...)" does not attempt to check the map size before attempting to check if the map contains the key

We also create a "canSee" method tailored for "ChunkMap#updatePlayer()", a method without the equals check (the "updatePlayer()" already checks if the entity is the same entity) because the CraftPlayer's `equals()` check is a *bit* expensive compared to only checking the object's identity, and because the identity has already been check, we don't need to check it twice.

diff --git a/net/minecraft/server/level/ChunkMap.java b/net/minecraft/server/level/ChunkMap.java
index a95feb65b392a971ac570dd3fd771b6ff89a2684..c60b9e4076450de2157c1a3cf4f98cc2c19e4e6a 100644
--- a/net/minecraft/server/level/ChunkMap.java
+++ b/net/minecraft/server/level/ChunkMap.java
@@ -1295,7 +1295,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
                 flag = flag && this.entity.broadcastToPlayer(player) && ChunkMap.this.isChunkTracked(player, this.entity.chunkPosition().x, this.entity.chunkPosition().z);
                 // Paper end - Configurable entity tracking range by Y
                 // CraftBukkit start - respect vanish API
-                if (flag && !player.getBukkitEntity().canSee(this.entity.getBukkitEntity())) { // Paper - only consider hits
+                if (flag && !player.getBukkitEntity().canSeeChunkMapUpdatePlayer(this.entity.getBukkitEntity())) { // Paper - only consider hits // SparklyPaper - optimize canSee checks
                     flag = false;
                 }
                 // CraftBukkit end