Gale/gale-server/minecraft-patches/features/0096-Reduce-line-of-sight-updates-and-cache-lookups.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Martijn Muijsers <martijnmuijsers@live.nl>
Date: Wed, 30 Aug 2023 20:01:31 +0200
Subject: [PATCH] Reduce line of sight updates and cache lookups

License: GPL-3.0 (https://www.gnu.org/licenses/gpl-3.0.html)
Gale - https://galemc.org

This patch is based on the following patch:
"feat: reduce sensor work"
By: peaches94 <peachescu94@gmail.com>
As part of: Petal (https://github.com/Bloom-host/Petal)
Licensed under: GPL-3.0 (https://www.gnu.org/licenses/gpl-3.0.html)

* Petal description *

this patch is focused around the sensors used for ai
delete the line of sight cache less often and use a faster nearby comparison

diff --git a/net/minecraft/world/entity/ai/sensing/Sensing.java b/net/minecraft/world/entity/ai/sensing/Sensing.java
index e17b1a2a95975d1eae5adaa679e027b9181dddbd..cc25f5838aec5ed9fca2fb8b0322fafad9397a46 100644
--- a/net/minecraft/world/entity/ai/sensing/Sensing.java
+++ b/net/minecraft/world/entity/ai/sensing/Sensing.java
@@ -7,33 +7,79 @@ import net.minecraft.world.entity.Mob;
 
 public class Sensing {
     private final Mob mob;
-    // Gale start - initialize line of sight cache with low capacity
-    private final IntSet seen = new IntOpenHashSet(2);
-    private final IntSet unseen = new IntOpenHashSet(2);
-    // Gale end - initialize line of sight cache with low capacity
+    private final it.unimi.dsi.fastutil.ints.Int2IntMap seen = new it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap(2); // Gale end - initialize line of sight cache with low capacity // Gale - Petal - reduce line of sight cache lookups - merge sets
+
+    // Gale start - Petal - reduce line of sight updates - expiring entity id lists
+    private final @org.jetbrains.annotations.NotNull it.unimi.dsi.fastutil.ints.IntList @org.jetbrains.annotations.Nullable [] expiring;
+    private int currentCacheAddIndex = 0;
+    private int nextToExpireIndex = 1;
+    // Gale end - Petal - reduce line of sight updates - expiring entity id lists
 
     public Sensing(Mob mob) {
         this.mob = mob;
+        // Gale start - Petal - reduce line of sight updates - expiring entity id lists
+        int updateLineOfSightInterval = org.galemc.gale.configuration.GaleGlobalConfiguration.get().smallOptimizations.reducedIntervals.updateEntityLineOfSight;
+
+        if (updateLineOfSightInterval <= 1) {
+            this.expiring = null;
+        } else {
+            this.expiring = new it.unimi.dsi.fastutil.ints.IntList[updateLineOfSightInterval];
+
+            for (int i = 0; i < updateLineOfSightInterval; i++) {
+                this.expiring[i] = new it.unimi.dsi.fastutil.ints.IntArrayList(0);
+            }
+        }
+        // Gale end - Petal - reduce line of sight updates - expiring entity id lists
     }
 
     public void tick() {
+        if (this.expiring == null) { // Gale - Petal - reduce line of sight updates
         this.seen.clear();
-        this.unseen.clear();
+            // Gale start - Petal - reduce line of sight updates
+        } else {
+            var expiringNow = this.expiring[this.nextToExpireIndex];
+
+            expiringNow.forEach(this.seen::remove);
+            expiringNow.clear();
+
+            this.currentCacheAddIndex++;
+
+            if (this.currentCacheAddIndex == this.expiring.length) {
+                this.currentCacheAddIndex = 0;
+            }
+
+            this.nextToExpireIndex++;
+
+            if (this.nextToExpireIndex == this.expiring.length) {
+                this.nextToExpireIndex = 0;
+            }
+        }
+        // Gale end - Petal - reduce line of sight updates
     }
 
     public boolean hasLineOfSight(Entity entity) {
         int id = entity.getId();
-        if (this.seen.contains(id)) {
+        // Gale start - Petal - reduce line of sight cache lookups - merge sets
+        int cached = this.seen.get(id);
+
+        if (cached == 1) {
+            // Gale end - Petal - reduce line of sight cache lookups - merge sets
             return true;
-        } else if (this.unseen.contains(id)) {
+        } else if (cached == 2) { // Gale - Petal - reduce line of sight cache lookups - merge sets
             return false;
         } else {
             boolean hasLineOfSight = this.mob.hasLineOfSight(entity);
             if (hasLineOfSight) {
-                this.seen.add(id);
+                this.seen.put(id, 1); // Gale - Petal - reduce line of sight cache lookups - merge sets
             } else {
-                this.unseen.add(id);
+                this.seen.put(id, 2); // Gale - Petal - reduce line of sight cache lookups - merge sets
+            }
+
+            // Gale start - Petal - reduce line of sight updates
+            if (this.expiring != null) {
+                this.expiring[this.currentCacheAddIndex].add(id);
             }
+            // Gale end - Petal - reduce line of sight updates
 
             return hasLineOfSight;
         }