From 4459bbeebd6fa1f326768c5c898358d8fd7f8c7d Mon Sep 17 00:00:00 2001
From: themode <themode@outlook.fr>
Date: Sun, 13 Feb 2022 07:51:47 +0100
Subject: [PATCH] Cleanup view tracking

---
 .../net/minestom/server/entity/Entity.java    |  5 ++++-
 .../net/minestom/server/instance/Chunk.java   |  3 +--
 .../net/minestom/server/utils/ViewEngine.java | 20 +++++++++----------
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/main/java/net/minestom/server/entity/Entity.java b/src/main/java/net/minestom/server/entity/Entity.java
index f60d6874a..04e28ebbc 100644
--- a/src/main/java/net/minestom/server/entity/Entity.java
+++ b/src/main/java/net/minestom/server/entity/Entity.java
@@ -129,7 +129,10 @@ public class Entity implements Viewable, Tickable, Schedulable, TagHandler, Perm
 
         @Override
         public void referenceUpdate(@NotNull Point point, @Nullable EntityTracker tracker) {
-            viewEngine.updateTracker(instance, point, tracker);
+            final Instance currentInstance = tracker != null ? instance : null;
+            assert currentInstance == null || currentInstance.getEntityTracker() == tracker :
+                    "EntityTracker does not match current instance";
+            viewEngine.updateTracker(currentInstance, point);
         }
     };
 
diff --git a/src/main/java/net/minestom/server/instance/Chunk.java b/src/main/java/net/minestom/server/instance/Chunk.java
index bf6c29e80..6570debe4 100644
--- a/src/main/java/net/minestom/server/instance/Chunk.java
+++ b/src/main/java/net/minestom/server/instance/Chunk.java
@@ -68,8 +68,7 @@ public abstract class Chunk implements Block.Getter, Block.Setter, Biome.Getter,
         this.minSection = instance.getDimensionType().getMinY() / CHUNK_SECTION_SIZE;
         this.maxSection = (instance.getDimensionType().getMinY() + instance.getDimensionType().getHeight()) / CHUNK_SECTION_SIZE;
 
-        final EntityTracker tracker = instance.getEntityTracker();
-        this.viewers.updateTracker(instance, toPosition(), tracker);
+        this.viewers.updateTracker(instance, toPosition());
     }
 
     /**
diff --git a/src/main/java/net/minestom/server/utils/ViewEngine.java b/src/main/java/net/minestom/server/utils/ViewEngine.java
index f4151a5e6..05dc10d56 100644
--- a/src/main/java/net/minestom/server/utils/ViewEngine.java
+++ b/src/main/java/net/minestom/server/utils/ViewEngine.java
@@ -9,6 +9,7 @@ import net.minestom.server.entity.Player;
 import net.minestom.server.instance.EntityTracker;
 import net.minestom.server.instance.Instance;
 import net.minestom.server.instance.InstanceContainer;
+import net.minestom.server.instance.SharedInstance;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -30,7 +31,6 @@ public final class ViewEngine {
     private final Set<Player> manualViewers = new HashSet<>();
 
     private Instance instance;
-    private EntityTracker tracker;
     private Point lastPoint;
 
     // Decide if this entity should be viewable to X players
@@ -58,11 +58,10 @@ public final class ViewEngine {
         this(null);
     }
 
-    public void updateTracker(@NotNull Instance instance, @NotNull Point point, @Nullable EntityTracker tracker) {
+    public void updateTracker(@Nullable Instance instance, @NotNull Point point) {
         synchronized (mutex) {
             this.instance = instance;
             this.lastPoint = point;
-            this.tracker = tracker;
         }
     }
 
@@ -208,18 +207,19 @@ public final class ViewEngine {
         }
 
         private Stream<T> references() {
-            if (tracker == null) return Stream.empty();
-            var references = tracker.references(lastPoint, range, target);
-            var result = references.stream().flatMap(Collection::stream);
-            if (instance != null && instance instanceof InstanceContainer container) {
+            final Instance instance = ViewEngine.this.instance;
+            if (instance == null) return Stream.empty();
+            var references = instance.getEntityTracker().references(lastPoint, range, target);
+            Stream<T> result = references.stream().flatMap(Collection::stream);
+            if (instance instanceof InstanceContainer container) {
                 // References from shared instances must be added to the result.
-                var shared = container.getSharedInstances();
+                final List<SharedInstance> shared = container.getSharedInstances();
                 if (!shared.isEmpty()) {
-                    var tmp = shared.stream().<List<T>>mapMulti((inst, consumer) -> {
+                    Stream<T> sharedInstanceStream = shared.stream().<List<T>>mapMulti((inst, consumer) -> {
                         var ref = inst.getEntityTracker().references(lastPoint, range, target);
                         ref.forEach(consumer);
                     }).flatMap(Collection::stream);
-                    result = Stream.concat(result, tmp);
+                    result = Stream.concat(result, sharedInstanceStream);
                 }
             }
             return result;