Leaf/leaf-server/paper-patches/features/0043-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 e60440562720c61f4a5e9abb771420eed3df852b..74722575f8d835dc1571972de37d0a4bd50d52e2 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -768,7 +768,7 @@ 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());
             }
         }
@@ -1099,7 +1099,7 @@ 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());
         }
     }
@@ -1246,7 +1246,7 @@ 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 5186672c20ec1b0e66d1e639f02a15a08ed4a9c4..a983f7e07377c69dfac286085b71a8a2e2f15dbf 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -2887,7 +2887,7 @@ 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 98b766d115856dbf3ea11a983c1304591032f1b0..62cefed7674a6938698a57f5f89750d120461e9c 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -1798,6 +1798,26 @@ 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);