Paper/patches/server/0727-Prevent-entity-loading-causing-async-lookups.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Owen1212055 <23108066+Owen1212055@users.noreply.github.com>
Date: Sun, 6 Mar 2022 11:09:09 -0500
Subject: [PATCH] Prevent entity loading causing async lookups


diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 3bd13975934e8f61b41c4c08b73ead6e0f45ffac..bcf4e77ed17fa35d509b33568793a38278e2b718 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -740,6 +740,7 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
 
     public void baseTick() {
         this.level().getProfiler().push("entityBaseTick");
+        if (firstTick && this instanceof net.minecraft.world.entity.NeutralMob neutralMob) neutralMob.tickInitialPersistentAnger(level); // Paper - Prevent entity loading causing async lookups
         this.inBlockState = null;
         if (this.isPassenger() && this.getVehicle().isRemoved()) {
             this.stopRiding();
diff --git a/src/main/java/net/minecraft/world/entity/NeutralMob.java b/src/main/java/net/minecraft/world/entity/NeutralMob.java
index 7bb01b28b07bf2b31897cc5ab1f44fc0387958bb..1bc49da1c4cc12966ca414152b3ddf7f850c7d44 100644
--- a/src/main/java/net/minecraft/world/entity/NeutralMob.java
+++ b/src/main/java/net/minecraft/world/entity/NeutralMob.java
@@ -42,24 +42,11 @@ public interface NeutralMob {
                 UUID uuid = nbt.getUUID("AngryAt");
 
                 this.setPersistentAngerTarget(uuid);
-                Entity entity = ((ServerLevel) world).getEntity(uuid);
-
-                if (entity != null) {
-                    if (entity instanceof Mob) {
-                        Mob entityinsentient = (Mob) entity;
-
-                        this.setTarget(entityinsentient);
-                        this.setLastHurtByMob(entityinsentient);
-                    }
-
-                    if (entity instanceof Player) {
-                        Player entityhuman = (Player) entity;
-
-                        this.setTarget(entityhuman);
-                        this.setLastHurtByPlayer(entityhuman);
-                    }
-
-                }
+                // Paper - Prevent entity loading causing async lookups; Moved diff to separate method
+                // If this entity already survived its first tick, e.g. is loaded and ticked in sync, actively
+                // tick the initial persistent anger.
+                // If not, let the first tick on the baseTick call the method later down the line.
+                if (this instanceof Entity entity && !entity.firstTick) this.tickInitialPersistentAnger(world);
             }
         }
     }
@@ -133,4 +120,28 @@ public interface NeutralMob {
 
     @Nullable
     LivingEntity getTarget();
+
+    // Paper start - Prevent entity loading causing async lookups
+    // Update last hurt when ticking
+    default void tickInitialPersistentAnger(Level level) {
+        UUID target = getPersistentAngerTarget();
+        if (target == null) {
+            return;
+        }
+
+        Entity entity = ((ServerLevel) level).getEntity(target);
+
+        if (entity != null) {
+            if (entity instanceof Mob mob) {
+                this.setTarget(mob, org.bukkit.event.entity.EntityTargetEvent.TargetReason.TARGET_ATTACKED_ENTITY, true);
+                this.setLastHurtByMob(mob);
+            }
+
+            if (entity instanceof Player player) {
+                this.setTarget(player, org.bukkit.event.entity.EntityTargetEvent.TargetReason.TARGET_ATTACKED_ENTITY, true);
+                this.setLastHurtByPlayer(player);
+            }
+        }
+    }
+    // Paper end - Prevent entity loading causing async lookups
 }