From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MrPowerGamerBR <git@mrpowergamerbr.com>
Date: Sun, 19 Nov 2023 12:35:16 -0300
Subject: [PATCH] Skip EntityScheduler's executeTick checks if there isn't any
 tasks to be run

On each tick, Paper runs EntityScheduler's executeTick of each entity. This is a bit expensive, due to ArrayDeque's size() call because it ain't a simple "get the current queue size" function, due to the thread checks, and because it needs to iterate all entities in all worlds.

To avoid the hefty ArrayDeque's size() call, we check if we *really* need to execute the executeTick, by adding all entities with scheduled tasks to a global set.

Most entities won't have any scheduled tasks, so this is a nice performance bonus. These optimizations, however, wouldn't work in a Folia environment, but because in SparklyPaper executeTick is always executed on the main thread, it ain't an issue for us (yay).

diff --git a/net/minecraft/server/MinecraftServer.java b/net/minecraft/server/MinecraftServer.java
index ae220a732c78ab076261f20b5a54c71d7fceb407..6ad6bfe60026be304aa2178d5f04a79531cc66a6 100644
--- a/net/minecraft/server/MinecraftServer.java
+++ b/net/minecraft/server/MinecraftServer.java
@@ -303,6 +303,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
     public boolean isIteratingOverLevels = false; // Paper - Throw exception on world create while being ticked
     private final Set<String> pluginsBlockingSleep = new java.util.HashSet<>(); // Paper - API to allow/disallow tick sleeping
     public static final long SERVER_INIT = System.nanoTime(); // Paper - Lag compensation
+    public final Set<net.minecraft.world.entity.Entity> entitiesWithScheduledTasks = java.util.concurrent.ConcurrentHashMap.newKeySet(); // SparklyPaper - skip EntityScheduler's executeTick checks if there isn't any tasks to be run (concurrent because plugins may schedule tasks async)
 
     public static <S extends MinecraftServer> S spin(Function<Thread, S> threadFunction) {
         ca.spottedleaf.dataconverter.minecraft.datatypes.MCTypeRegistry.init(); // Paper - rewrite data converter system
@@ -1659,6 +1660,18 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
         this.server.getScheduler().mainThreadHeartbeat(); // CraftBukkit
         // Paper start - Folia scheduler API
         ((io.papermc.paper.threadedregions.scheduler.FoliaGlobalRegionScheduler) org.bukkit.Bukkit.getGlobalRegionScheduler()).tick();
+        // SparklyPaper - skip EntityScheduler's executeTick checks if there isn't any tasks to be run
+        for (final net.minecraft.world.entity.Entity entity : entitiesWithScheduledTasks) {
+            if (entity.isRemoved()) {
+                continue;
+            }
+
+            final org.bukkit.craftbukkit.entity.CraftEntity bukkit = entity.getBukkitEntityRaw();
+            if (bukkit != null) {
+                bukkit.taskScheduler.executeTick();
+            }
+        }
+        /*
         getAllLevels().forEach(level -> {
             for (final net.minecraft.world.entity.Entity entity : level.getEntities().getAll()) {
                 if (entity.isRemoved()) {
@@ -1670,6 +1683,8 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
                 }
             }
         });
+        */
+        // SparklyPaper end
         // Paper end - Folia scheduler API
         io.papermc.paper.adventure.providers.ClickCallbackProviderImpl.CALLBACK_MANAGER.handleQueue(this.tickCount); // Paper
         profilerFiller.push("commandFunctions");