Paper/Spigot-Server-Patches/0262-Ignore-Dead-Entities-in-entityList-iteration.patch

From 8a2267af66d0af048717527cfeaf8af8f031e25c 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 b839769cea..5acad8e44f 100644
--- a/src/main/java/com/destroystokyo/paper/PaperCommand.java
+++ b/src/main/java/com/destroystokyo/paper/PaperCommand.java
@@ -179,6 +179,7 @@ public class PaperCommand extends Command {
                 Collection<Entity> entities = world.entitiesById.values();
                 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/Chunk.java b/src/main/java/net/minecraft/server/Chunk.java
index 0afa8a7ebd..8e9ddca049 100644
--- a/src/main/java/net/minecraft/server/Chunk.java
+++ b/src/main/java/net/minecraft/server/Chunk.java
@@ -810,6 +810,7 @@ public class Chunk implements IChunkAccess {
 
                 while (iterator.hasNext()) {
                     Entity entity1 = (Entity) iterator.next();
+                    if (entity1.shouldBeRemoved) continue; // Paper
 
                     if (entity1.getBoundingBox().c(axisalignedbb) && entity1 != entity) {
                         if (predicate == null || predicate.test(entity1)) {
@@ -847,6 +848,7 @@ public class Chunk implements IChunkAccess {
 
             while (iterator.hasNext()) {
                 T entity = (T) iterator.next(); // CraftBukkit - decompile error
+                if (entity.shouldBeRemoved) continue; // Paper
 
                 if ((entitytypes == null || entity.getEntityType() == entitytypes) && entity.getBoundingBox().c(axisalignedbb) && predicate.test(entity)) {
                     list.add(entity);
@@ -868,6 +870,7 @@ public class Chunk implements IChunkAccess {
 
             while (iterator.hasNext()) {
                 T t0 = (T) iterator.next(); // CraftBukkit - decompile error
+                if (t0.shouldBeRemoved) continue; // Paper
 
                 if (oclass.isInstance(t0) && t0.getBoundingBox().c(axisalignedbb) && (predicate == null || predicate.test(t0))) { // Spigot - instance check
                     list.add(t0);
diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index 838aa7da69..35d22ec027 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -195,6 +195,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     protected int numCollisions = 0; // Paper
     public void inactiveTick() { }
     // Spigot end
+    public boolean shouldBeRemoved; // Paper
 
     public float getBukkitYaw() {
         return this.yaw;
diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
index d1424325d5..f071b61195 100644
--- a/src/main/java/net/minecraft/server/WorldServer.java
+++ b/src/main/java/net/minecraft/server/WorldServer.java
@@ -908,7 +908,7 @@ public class WorldServer extends World {
 
         while (objectiterator.hasNext()) {
             Entity entity = (Entity) objectiterator.next();
-
+            if (entity.shouldBeRemoved) continue; // Paper
             if (entity instanceof EntityInsentient) {
                 EntityInsentient entityinsentient = (EntityInsentient) entity;
 
@@ -1242,6 +1242,7 @@ public class WorldServer extends World {
                 entity.origin = entity.getBukkitEntity().getLocation();
             }
             // Paper end
+            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
         }
 
@@ -1254,6 +1255,7 @@ public class WorldServer extends World {
             this.removeEntityFromChunk(entity);
             this.entitiesById.remove(entity.getId());
             this.unregisterEntity(entity);
+            entity.shouldBeRemoved = true; // Paper
         }
     }
 
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
index cde999c97f..960e29cb16 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -1029,6 +1029,7 @@ public class CraftWorld implements World {
         for (Object o : world.entitiesById.values()) {
             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
@@ -1048,6 +1049,7 @@ public class CraftWorld implements World {
         for (Object o : world.entitiesById.values()) {
             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
@@ -1074,6 +1076,7 @@ public class CraftWorld implements World {
 
         for (Object entity: world.entitiesById.values()) {
             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) {
@@ -1097,6 +1100,7 @@ public class CraftWorld implements World {
 
         for (Object entity: world.entitiesById.values()) {
             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) {
-- 
2.26.0