From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: NONPLAYT <76615486+NONPLAYT@users.noreply.github.com>
Date: Sat, 1 Feb 2025 19:52:39 +0300
Subject: [PATCH] SparklyPaper: Optimize "canSee" checks

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

Patch description:

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/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index bc5fac66b3c4ebce77b0b84e0ec5a525e2efec62..fde41d3afad329d9dc85343b7d3126f7f053efc0 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -234,7 +234,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player, PluginMessa
     private long lastPlayed = 0;
     private boolean hasPlayedBefore = false;
     private final ConversationTracker conversationTracker = new ConversationTracker();
-    private final Map<UUID, Set<WeakReference<Plugin>>> invertedVisibilityEntities = new HashMap<>();
+    private final Map<UUID, Set<WeakReference<Plugin>>> invertedVisibilityEntities = new it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap<>(); // DivineMC - SparklyPaper: Optimize "canSee" checks
     private final Set<UUID> unlistedEntities = new HashSet<>(); // Paper - Add Listing API for Player
     private static final WeakHashMap<Plugin, WeakReference<Plugin>> pluginWeakReferences = new WeakHashMap<>();
     private int hash = 0;
@@ -2140,9 +2140,15 @@ public class CraftPlayer extends CraftHumanEntity implements Player, PluginMessa
 
     @Override
     public boolean canSee(org.bukkit.entity.Entity entity) {
-        return this.equals(entity) || entity.isVisibleByDefault() ^ this.invertedVisibilityEntities.containsKey(entity.getUniqueId()); // SPIGOT-7312: Can always see self
+        return this.equals(entity) || entity.isVisibleByDefault() ^ (!invertedVisibilityEntities.isEmpty() && this.invertedVisibilityEntities.containsKey(entity.getUniqueId())); // SPIGOT-7312: Can always see self // DivineMC - SparklyPaper: Optimize "canSee" checks
     }
 
+    // DivineMC start - SparklyPaper: Optimize "canSee" checks
+    public boolean canSeeChunkMapUpdatePlayer(org.bukkit.entity.Entity entity) {
+        return entity.isVisibleByDefault() ^ (!invertedVisibilityEntities.isEmpty() && this.invertedVisibilityEntities.containsKey(entity.getUniqueId()));
+    }
+    // DivineMC end - SparklyPaper: Optimize "canSee" checks
+
     public boolean canSeePlayer(UUID uuid) {
         org.bukkit.entity.Entity entity = this.getServer().getPlayer(uuid);