Make Techhider more robust

HiderCore/src/de/steamwar/hullhider/Hull.java

@@ -53,6 +53,7 @@ import org.bukkit.entity.Player;
 import org.bukkit.plugin.Plugin;
 
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.logging.Level;
@@ -81,8 +82,9 @@ public class Hull {
     private final HashSet<IntVector> uncoveredSurface = new HashSet<>();
 
     private final Viewers viewers;
-    private final HashSet<Entity> entities = new HashSet<>();
-    private final HashSet<REntity> rentities = new HashSet<>();
+    // Concurrent as it is read on netty threads, keyed by entity id
+    private final Map<Integer, Entity> entities = new ConcurrentHashMap<>();
+    private final Set<REntity> rentities = ConcurrentHashMap.newKeySet();
 
     /**
      * @param groundVisible whether the bottom layer of the region is uncovered (if the region does not reach the ground)
@@ -162,6 +164,10 @@ public class Hull {
         return region.contains(x, y, z) && !isViewer(player) && !visibility.get(region.toIndex(x, y, z));
     }
 
+    public boolean isEntityHidden(Player player, int entityId) {
+        return player.getEntityId() != entityId && entities.containsKey(entityId) && !isViewer(player);
+    }
+
     public boolean isViewer(Player player) {
         return player != null && viewers.isViewer(player);
     }
@@ -187,13 +193,13 @@ public class Hull {
     private void updateEntities(Player player, boolean wasViewer) {
         if (isViewer(player)) {
             if (!wasViewer) {
-                for (Entity entity : entities) {
+                for (Entity entity : entities.values()) {
                     trackEntity(player, entity);
                 }
             }
         } else {
             // Also hides the entities from players that joined after they were hidden
-            for (Entity entity : entities) {
+            for (Entity entity : entities.values()) {
                 if (!player.equals(entity)) untrackEntity(player, entity);
             }
         }
@@ -210,13 +216,13 @@ public class Hull {
     public void checkEntity(Entity entity) {
         Location location = entity.getLocation();
         if (region.contains(location) && !visibility.get(new IntVector(location).toId(region))) {
-            if (entities.add(entity)) {
+            if (entities.put(entity.getEntityId(), entity) == null) {
                 for (Player player : Bukkit.getOnlinePlayers()) {
                     if (!isViewer(player) && !player.equals(entity)) untrackEntity(player, entity);
                 }
             }
         } else {
-            if (entities.remove(entity)) {
+            if (entities.remove(entity.getEntityId()) != null) {
                 for (Player player : Bukkit.getOnlinePlayers()) {
                     if (!isViewer(player) && !player.equals(entity)) trackEntity(player, entity);
                 }
@@ -241,7 +247,7 @@ public class Hull {
     }
 
     public void removeEntity(Entity entity) {
-        entities.remove(entity);
+        entities.remove(entity.getEntityId());
     }
 
     public void checkREntity(REntity entity) {
@@ -264,7 +270,7 @@ public class Hull {
         for (Player player : Bukkit.getOnlinePlayers()) {
             if (isViewer(player)) continue;
 
-            for (Entity entity : entities) {
+            for (Entity entity : entities.values()) {
                 if (!player.equals(entity)) trackEntity(player, entity);
             }
         }

HiderCore/src/de/steamwar/hullhider/HullHider.java

@@ -146,6 +146,16 @@ public class HullHider<K> implements Listener {
         return false;
     }
 
+    public boolean isEntityHidden(Player player, int entityId) {
+        for (Hull hull : hulls) {
+            if (hull.isEntityHidden(player, entityId)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
     public void onBlockPhysic(BlockPhysicsEvent e) {
         if (e.getBlock() == e.getSourceBlock() || e.getChangedType() == Material.AIR) {

HiderCore/src/de/steamwar/techhider/ChunkHider.java

@@ -30,7 +30,8 @@ import net.minecraft.util.SimpleBitStorage;
 import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.entity.BlockEntityType;
 import net.minecraft.world.level.block.state.BlockState;
-import org.bukkit.entity.Player;
+import org.bukkit.Bukkit;
+import org.bukkit.World;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -48,6 +49,15 @@ public class ChunkHider {
     private final int BLOCKS_PER_SECTION = 4096;
     private final int BIOMES_PER_SECTION = 64;
 
+    private final int worldMinHeight;
+    private final int worldMaxHeight;
+
+    public ChunkHider() {
+        World world = Bukkit.getWorlds().getFirst();
+        worldMinHeight = world.getMinHeight();
+        worldMaxHeight = world.getMaxHeight();
+    }
+
     private int getLongsRequiredToEncodeEntries(int bitsPerEntry, int entryCount) {
         int entriesPerLong = Long.SIZE / bitsPerEntry;
         int dataLengthAsLongCount = (entryCount + entriesPerLong - 1) / entriesPerLong;
@@ -67,7 +77,6 @@ public class ChunkHider {
     }
 
     public ClientboundLevelChunkWithLightPacket processLevelChunkWithLightPacket(ForPlayer access, ClientboundLevelChunkWithLightPacket packet) {
-        Player player = access.getPlayer();
         int chunkX = packet.getX();
         int chunkZ = packet.getZ();
         ClientboundLevelChunkPacketData chunkData = packet.getChunkData();
@@ -75,9 +84,6 @@ public class ChunkHider {
         ByteBuf in = Unpooled.wrappedBuffer(chunkData.getReadBuffer());
         ByteBuf out = Unpooled.buffer(in.readableBytes() + 64);
 
-        int worldMinHeight = player.getWorld().getMinHeight();
-        int worldMaxHeight = player.getWorld().getMaxHeight();
-
         for (int yOffset = worldMinHeight; yOffset < worldMaxHeight; yOffset += SECTION_SPAN_SIZE) {
             short blockCount = in.readShort();