Leaf/leaf-server/paper-patches/features/0023-Multithreaded-Tracker.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: peaches94 <peachescu94@gmail.com>
Date: Sat, 2 Jul 2022 00:35:56 -0500
Subject: [PATCH] Multithreaded Tracker

Original license: GPL v3
Original project: https://github.com/Bloom-host/Petal

Original license: GPL v3
Original project: https://github.com/TECHNOVE/Airplane-Experimental

Co-authored-by: Paul Sauve <paul@technove.co>
Co-authored-by: Kevin Raneri <kevin.raneri@gmail.com>
Co-authored-by: HaHaWTH <102713261+HaHaWTH@users.noreply.github.com>

This patch refactored from original multithreaded tracker (Petal version),
and is derived from the Airplane fork by Paul Sauve, the tree is like:
Airplane -> Pufferfish? -> Petal -> Leaf

We made much of tracking logic asynchronously, and fixed visible issue
for the case of some NPC plugins which using real entity type, e.g. Citizens.

But it is still recommending to use those packet based, virtual entity
based NPC plugins, e.g. ZNPC Plus, Adyeshach, Fancy NPC, etc.

diff --git a/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java b/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java
index 379c2dc1853e45a96dda9b13bf28b7e08f65658a..361f4de9cdf0f7505628a2fed2a3f5366031e04b 100644
--- a/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java
+++ b/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java
@@ -42,6 +42,12 @@ class PaperEventManager {
         if (event.isAsynchronous() && this.server.isPrimaryThread()) {
             throw new IllegalStateException(event.getEventName() + " may only be triggered asynchronously.");
         } else if (!event.isAsynchronous() && !this.server.isPrimaryThread() && !this.server.isStopping()) {
+            // Leaf start - Multithreaded tracker
+            if (org.dreeam.leaf.config.modules.async.MultithreadedTracker.enabled) {
+                net.minecraft.server.MinecraftServer.getServer().scheduleOnMain(event::callEvent);
+                return;
+            }
+            // Leaf end - Multithreaded tracker
             throw new IllegalStateException(event.getEventName() + " may only be triggered synchronously.");
         }
         // Leaves start - skip photographer
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
index edcd209798740f31cb302f36d7864a0d8ea1d561..e8b80ac3d2a54b9e855cad80c8a782007f5ea726 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -749,7 +749,7 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
         ChunkMap.TrackedEntity entityTracker = world.getChunkSource().chunkMap.entityMap.get(this.getEntityId());
 
         if (entityTracker != null) {
-            for (ServerPlayerConnection connection : entityTracker.seenBy) {
+            for (ServerPlayerConnection connection : entityTracker.seenBy()) { // Leaf - Multithreaded tracker
                 players.add(connection.getPlayer().getBukkitEntity());
             }
         }
@@ -1057,7 +1057,7 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
         }
 
         // Paper start - resend possibly desynced entity instead of add entity packet
-        for (final ServerPlayerConnection connection : entityTracker.seenBy) {
+        for (final ServerPlayerConnection connection : entityTracker.seenBy()) { // Leaf - Multithreaded tracker
             this.getHandle().resendPossiblyDesyncedEntityData(connection.getPlayer());
         }
         // Paper end - resend possibly desynced entity instead of add entity packet
@@ -1245,7 +1245,7 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
         }
 
         Set<org.bukkit.entity.Player> set = new java.util.HashSet<>(tracker.seenBy.size());
-        for (net.minecraft.server.network.ServerPlayerConnection connection : tracker.seenBy) {
+        for (net.minecraft.server.network.ServerPlayerConnection connection : tracker.seenBy()) { // Leaf - Multithreaded tracker
             set.add(connection.getPlayer().getBukkitEntity().getPlayer());
         }
         return set;
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index 8e8630db9f74e5952142dba14ec58917c5745287..f89f6cea94486842a5e9015200a0d648225c8615 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -2915,7 +2915,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         Iterator<AttributeInstance> iterator = collection.iterator();
         while (iterator.hasNext()) {
             AttributeInstance genericInstance = iterator.next();
-            if (genericInstance.getAttribute() == Attributes.MAX_HEALTH) {
+            if (genericInstance != null && genericInstance.getAttribute() == Attributes.MAX_HEALTH) { // Leaf - Multithreaded tracker
                 iterator.remove();
                 break;
             }
diff --git a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
index e52479f3c888268fd1febeb78e9965af834a8ae9..c2552c3706831f7012b5b449fa43c7d5990056a4 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -1973,6 +1973,26 @@ public class CraftEventFactory {
     }
 
     public static boolean handleBlockFormEvent(Level world, BlockPos pos, net.minecraft.world.level.block.state.BlockState block, int flag, @Nullable Entity entity) {
+        // Leaf start - Multithreaded tracker
+        if (org.dreeam.leaf.config.modules.async.MultithreadedTracker.enabled && Thread.currentThread() instanceof org.dreeam.leaf.async.tracker.MultithreadedTracker.MultithreadedTrackerThread) {
+            java.util.concurrent.CompletableFuture<Boolean> future = new java.util.concurrent.CompletableFuture<>();
+            net.minecraft.server.MinecraftServer.getServer().scheduleOnMain(() -> {
+                CraftBlockState blockState = CraftBlockStates.getBlockState(world, pos, flag);
+                blockState.setData(block);
+
+                BlockFormEvent event = (entity == null) ? new BlockFormEvent(blockState.getBlock(), blockState) : new EntityBlockFormEvent(entity.getBukkitEntity(), blockState.getBlock(), blockState);
+                world.getCraftServer().getPluginManager().callEvent(event);
+
+                if (!event.isCancelled()) {
+                    blockState.update(true);
+                }
+
+                future.complete(!event.isCancelled());
+            });
+
+            return future.join();
+        }
+        // Leaf end - Multithreaded tracker
         CraftBlockState blockState = CraftBlockStates.getBlockState(world, pos, flag);
         blockState.setData(block);