New atomic boolean to lock down destruction

src/engine/objects/Building.java

@@ -505,6 +505,11 @@ public class Building extends AbstractWorldObject {
             return;
         }
 
+        if (this.isDeranking.compareAndSet(false, true) == false) {
+            Logger.error("Attempt to derank tol twice");
+            return;
+        }
+
         bane = city.getBane();
 
         // We need to collect the spires and shrines on the citygrid in case
@@ -600,8 +605,6 @@ public class Building extends AbstractWorldObject {
 
             newOwner = Guild.GetGL(bane.getOwner().getGuild());
 
-            this.isDeranking.compareAndSet(false, true);
-
             if ((bane.getOwner().getGuild().getGuildState() == GuildState.Sovereign) ||
                     (bane.getOwner().getGuild().getGuildState() == GuildState.Protectorate) ||
                     (bane.getOwner().getGuild().getGuildState() == GuildState.Province) ||

src/engine/objects/City.java

@@ -41,6 +41,7 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 public class City extends AbstractWorldObject {
@@ -80,6 +81,7 @@ public class City extends AbstractWorldObject {
     private String hash;
     public Warehouse warehouse;
     public Realm realm;
+    public AtomicBoolean isDestroyed = new AtomicBoolean();
 
     /**
      * ResultSet Constructor
@@ -1102,6 +1104,11 @@ public class City extends AbstractWorldObject {
 
     public final void destroy() {
 
+        if (this.isDestroyed.compareAndSet(false, true) == false) {
+            Logger.error("Attempt to destroy tol twice");
+            return;
+        }
+
         Thread destroyCityThread = new Thread(new DestroyCityThread(this));
 
         destroyCityThread.setName("destroyCity: " + this.getName());