Leaf/leaf-server/paper-patches/features/0042-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 beae8a57a0ce9b8e7d81619efe4c39d908869319..6b1926080eddf61ff9c0156a6846f7f0bcff1c2d 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -764,7 +764,7 @@ 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());
             }
         }
@@ -1095,7 +1095,7 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
             return;
         }
 
-        for (final ServerPlayerConnection connection : entityTracker.seenBy) {
+        for (final ServerPlayerConnection connection : entityTracker.seenBy()) { // Leaf - Multithreaded tracker
             this.getHandle().resendPossiblyDesyncedEntityData(connection.getPlayer());
         }
     }
@@ -1242,7 +1242,7 @@ 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 384b11fdf3606f0ee59ea1e58a3a312e3898fce6..15d549931183e0c9a7dc54737fc2947af58934b0 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -2845,7 +2845,7 @@ 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 a162440a583801671787163d998d6b9546ef7e61..5e73db484a5526f4c39c7cc2de5ddc3ff037d2e4 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -1808,6 +1808,26 @@ public class CraftEventFactory {
     }
 
     public static boolean handleBlockFormEvent(Level world, BlockPos pos, net.minecraft.world.level.block.state.BlockState state, int flags, @Nullable Entity entity, boolean checkSetResult) {
+        // 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(() -> {
+                boolean resultFlag = false;
+                CraftBlockState snapshot = CraftBlockStates.getBlockState(world, pos);
+                snapshot.setData(state);
+
+                BlockFormEvent event = (entity == null) ? new BlockFormEvent(snapshot.getBlock(), snapshot) : new EntityBlockFormEvent(entity.getBukkitEntity(), snapshot.getBlock(), snapshot);
+                if (event.callEvent()) {
+                    boolean result = snapshot.place(flags);
+                    resultFlag = !checkSetResult || result;
+                }
+
+                future.complete(resultFlag);
+            });
+
+            return future.join();
+        }
+        // Leaf end - Multithreaded tracker
         CraftBlockState snapshot = CraftBlockStates.getBlockState(world, pos);
         snapshot.setData(state);