From 7c85d9fd4a96d659e3cffce2bd80eb3432c5be3a Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 28 Jul 2018 12:18:27 -0400
Subject: [PATCH] Ignore Dead Entities in entityList iteration

A spigot change delays removal of entities from the entity list.
This causes a change in behavior from Vanilla where getEntities type
methods will return dead entities that they shouldn't otherwise be doing.

This will ensure that dead entities are skipped from iteration since
they shouldn't of been in the list in the first place.

diff --git a/src/main/java/com/destroystokyo/paper/PaperCommand.java b/src/main/java/com/destroystokyo/paper/PaperCommand.java
index 7ff8e70b24..4e854c6dbe 100644
--- a/src/main/java/com/destroystokyo/paper/PaperCommand.java
+++ b/src/main/java/com/destroystokyo/paper/PaperCommand.java
@@ -172,6 +172,7 @@ public class PaperCommand extends Command {
                 List<Entity> entities = world.entityList;
                 entities.forEach(e -> {
                     MinecraftKey key = e.getMinecraftKey();
+                    if (e.shouldBeRemoved) return; // Paper
 
                     MutablePair<Integer, Map<ChunkCoordIntPair, Integer>> info = list.computeIfAbsent(key, k -> MutablePair.of(0, Maps.newHashMap()));
                     ChunkCoordIntPair chunk = new ChunkCoordIntPair(e.getChunkX(), e.getChunkZ());
diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index 785c31089e..6b0ca4eb98 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -122,6 +122,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     protected boolean F;
     private boolean az;
     public boolean dead;
+    public boolean shouldBeRemoved; // Paper
     public float width;
     public float length;
     public float J;
diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index ff0112c52a..82f4f00a76 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1078,6 +1078,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
         }
 
         entity.valid = true; // CraftBukkit
+        entity.shouldBeRemoved = false; // Paper - shouldn't be removed after being re-added
         new com.destroystokyo.paper.event.entity.EntityAddToWorldEvent(entity.getBukkitEntity()).callEvent(); // Paper - fire while valid
     }
 
@@ -1143,6 +1144,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
         if (entity.inChunk && this.isChunkLoaded(i, j, true)) {
             this.getChunkAt(i, j).b(entity);
         }
+        entity.shouldBeRemoved = true; // Paper
 
         if (!guardEntityList) { // Spigot - It will get removed after the tick if we are ticking // Paper - always remove from current chunk above
         // CraftBukkit start - Decrement loop variable field if we've already ticked this entity
@@ -2350,6 +2352,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
 
         while (iterator.hasNext()) {
             Entity entity = (Entity) iterator.next();
+            if (entity.shouldBeRemoved) continue; // Paper
 
             if (oclass.isAssignableFrom(entity.getClass()) && predicate.test((T) entity)) {
                 arraylist.add(entity);
@@ -2436,6 +2439,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
 
         while (iterator.hasNext()) {
             Entity entity = (Entity) iterator.next();
+            if (entity.shouldBeRemoved) continue; // Paper
             // CraftBukkit start - Split out persistent check, don't apply it to special persistent mobs
             if (entity instanceof EntityInsentient) {
                 EntityInsentient entityinsentient = (EntityInsentient) entity;
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
index f4dc7e4ac6..8923df898f 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -660,6 +660,7 @@ public class CraftWorld implements World {
         for (Object o : world.entityList) {
             if (o instanceof net.minecraft.server.Entity) {
                 net.minecraft.server.Entity mcEnt = (net.minecraft.server.Entity) o;
+                if (mcEnt.shouldBeRemoved) continue; // Paper
                 Entity bukkitEntity = mcEnt.getBukkitEntity();
 
                 // Assuming that bukkitEntity isn't null
@@ -678,6 +679,7 @@ public class CraftWorld implements World {
         for (Object o : world.entityList) {
             if (o instanceof net.minecraft.server.Entity) {
                 net.minecraft.server.Entity mcEnt = (net.minecraft.server.Entity) o;
+                if (mcEnt.shouldBeRemoved) continue; // Paper
                 Entity bukkitEntity = mcEnt.getBukkitEntity();
 
                 // Assuming that bukkitEntity isn't null
@@ -702,6 +704,7 @@ public class CraftWorld implements World {
 
         for (Object entity: world.entityList) {
             if (entity instanceof net.minecraft.server.Entity) {
+                if (((net.minecraft.server.Entity) entity).shouldBeRemoved) continue; // Paper
                 Entity bukkitEntity = ((net.minecraft.server.Entity) entity).getBukkitEntity();
 
                 if (bukkitEntity == null) {
@@ -724,6 +727,7 @@ public class CraftWorld implements World {
 
         for (Object entity: world.entityList) {
             if (entity instanceof net.minecraft.server.Entity) {
+                if (((net.minecraft.server.Entity) entity).shouldBeRemoved) continue; // Paper
                 Entity bukkitEntity = ((net.minecraft.server.Entity) entity).getBukkitEntity();
 
                 if (bukkitEntity == null) {
-- 
2.18.0