From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Tue, 24 Jun 2025 07:05:51 -0700
Subject: [PATCH] Optimise EntityScheduler ticking

The vast majority of the time, there are no tasks scheduled to
the EntityScheduler. We can avoid iterating the entire entity list
by tracking which schedulers have any tasks scheduled.

diff --git a/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/server/ServerEntityLookup.java b/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/server/ServerEntityLookup.java
index 5f2deeb5cc01d8bbeb7449bd4e59c466b3dfdf57..82824ae7ffbced513a8bcace684af94916135e84 100644
--- a/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/server/ServerEntityLookup.java
+++ b/ca/spottedleaf/moonrise/patches/chunk_system/level/entity/server/ServerEntityLookup.java
@@ -96,6 +96,7 @@ public final class ServerEntityLookup extends EntityLookup {
         if (entity instanceof ThrownEnderpearl enderpearl) {
             this.addEnderPearl(CoordinateUtils.getChunkKey(enderpearl.chunkPosition()));
         }
+        entity.registerScheduler(); // Paper - optimise Folia entity scheduler
     }
 
     @Override
diff --git a/net/minecraft/server/MinecraftServer.java b/net/minecraft/server/MinecraftServer.java
index 0a260fdf6b198a8ab52e60bf6db2fb5eab719c48..52fa5112cd90ba766c94512a02401dd3aee82cc9 100644
--- a/net/minecraft/server/MinecraftServer.java
+++ b/net/minecraft/server/MinecraftServer.java
@@ -1654,33 +1654,22 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
         }
     }
 
+    public final io.papermc.paper.threadedregions.EntityScheduler.EntitySchedulerTickList entitySchedulerTickList = new io.papermc.paper.threadedregions.EntityScheduler.EntitySchedulerTickList(); // Paper - optimise Folia entity scheduler
+
     protected void tickChildren(BooleanSupplier hasTimeLeft) {
         ProfilerFiller profilerFiller = Profiler.get();
         this.getPlayerList().getPlayers().forEach(serverPlayer1 -> serverPlayer1.connection.suspendFlushing());
         this.server.getScheduler().mainThreadHeartbeat(); // CraftBukkit
-        // Paper start - Folia scheduler API
-        ((io.papermc.paper.threadedregions.scheduler.FoliaGlobalRegionScheduler) org.bukkit.Bukkit.getGlobalRegionScheduler()).tick();
-        for (ServerPlayer player : this.playerList.players) {
-            if (!this.playerList.players.contains(player)) {
+        // Paper start - optimise Folia entity scheduler
+        ((io.papermc.paper.threadedregions.scheduler.FoliaGlobalRegionScheduler)org.bukkit.Bukkit.getGlobalRegionScheduler()).tick();
+        for (io.papermc.paper.threadedregions.EntityScheduler scheduler : this.entitySchedulerTickList.getAllSchedulers()) {
+            if (scheduler.isRetired()) {
                 continue;
             }
-            final org.bukkit.craftbukkit.entity.CraftEntity bukkit = player.getBukkitEntityRaw();
-            if (bukkit != null) {
-                bukkit.taskScheduler.executeTick();
-            }
+
+            scheduler.executeTick();
         }
-        getAllLevels().forEach(level -> {
-            for (final net.minecraft.world.entity.Entity entity : io.papermc.paper.FeatureHooks.getAllEntities(level)) {
-                if (entity.isRemoved() || entity instanceof ServerPlayer) {
-                    continue;
-                }
-                final org.bukkit.craftbukkit.entity.CraftEntity bukkit = entity.getBukkitEntityRaw();
-                if (bukkit != null) {
-                    bukkit.taskScheduler.executeTick();
-                }
-            }
-        });
-        // Paper end - Folia scheduler API
+        // Paper end - optimise Folia entity scheduler
         io.papermc.paper.adventure.providers.ClickCallbackProviderImpl.CALLBACK_MANAGER.handleQueue(this.tickCount); // Paper
         profilerFiller.push("commandFunctions");
         this.getFunctions().tick();
diff --git a/net/minecraft/world/entity/Entity.java b/net/minecraft/world/entity/Entity.java
index da880f52920b1101f23ef94f3fd0dbdea218c373..3d2c0a4d3a1f9d3e5cc6cd0cdb988ae1205de821 100644
--- a/net/minecraft/world/entity/Entity.java
+++ b/net/minecraft/world/entity/Entity.java
@@ -5165,6 +5165,11 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
         this.getBukkitEntity().taskScheduler.retire();
     }
     // Paper end - Folia schedulers
+    // Paper start - optimise Folia entity scheduler
+    public final void registerScheduler() {
+        this.getBukkitEntity().taskScheduler.registerTo(net.minecraft.server.MinecraftServer.getServer().entitySchedulerTickList);
+    }
+    // Paper end - optimise Folia entity scheduler
 
     @Override
     public void setLevelCallback(EntityInLevelCallback levelCallback) {