Super lock track method - Resolves GH-23

sources/src/main/java/io/akarin/server/mixin/core/MixinMinecraftServer.java

@@ -60,7 +60,6 @@ public abstract class MixinMinecraftServer {
             TileEntityHopper.skipHopperEvents = world.paperConfig.disableHopperMoveEvents || InventoryMoveItemEvent.getHandlerList().getRegisteredListeners().length == 0;
         }
         AkarinSlackScheduler.boot();
-        
     }
     
     @Overwrite

sources/src/main/java/io/akarin/server/mixin/core/MixinWorldManager.java

@@ -0,0 +1,27 @@
+package io.akarin.server.mixin.core;
+
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Overwrite;
+import org.spongepowered.asm.mixin.Shadow;
+
+import net.minecraft.server.Entity;
+import net.minecraft.server.EntityPlayer;
+import net.minecraft.server.WorldManager;
+import net.minecraft.server.WorldServer;
+
+@Mixin(value = WorldManager.class, remap = false)
+public abstract class MixinWorldManager {
+    @Shadow @Final private WorldServer world;
+    
+    @Overwrite
+    public void a(Entity entity) {
+        this.world.getTracker().entriesLock.lock(); // Akarin
+        this.world.getTracker().track(entity);
+        this.world.getTracker().entriesLock.unlock(); // Akarin
+        
+        if (entity instanceof EntityPlayer) {
+            this.world.worldProvider.a((EntityPlayer) entity);
+        }
+    }
+}

sources/src/main/java/net/minecraft/server/EntityPlayer.java

@@ -745,7 +745,9 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
         if (entity instanceof EntityPlayer) {
             WorldServer worldServer = (WorldServer) entity.getWorld();
             worldServer.tracker.untrackEntity(this);
+            worldServer.tracker.entriesLock.lock(); // Akarin
             worldServer.tracker.track(this);
+            worldServer.tracker.entriesLock.unlock(); // Akarin
         }
         // Paper end
 

sources/src/main/resources/mixins.akarin.core.json

@@ -21,6 +21,7 @@
         "core.MixinCommandKick",
         "core.MixinCraftServer",
         "core.MixinWorldServer",
+        "core.MixinWorldManager",
         "core.MixinCommandBanIp",
         "core.MixinChunkSection",
         "core.MixinAsyncCatcher",