Do not allow recursive creation of multiblocks. (#4472)

src/main/java/appeng/me/cluster/IAECluster.java

@@ -28,5 +28,11 @@ public interface IAECluster {
 
     void destroy();
 
+    /**
+     * @return True if the cluster has been destroyed, but not yet removed from a
+     *         tile entity. Usually true during destruction.
+     */
+    boolean isDestroyed();
+
     Iterator<IGridHost> getTiles();
 }

src/main/java/appeng/me/cluster/MBCalculator.java

@@ -18,6 +18,8 @@
 
 package appeng.me.cluster;
 
+import java.lang.ref.WeakReference;
+
 import net.minecraft.tileentity.TileEntity;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
@@ -29,16 +31,39 @@ import appeng.util.Platform;
 
 public abstract class MBCalculator {
 
+    private static WeakReference<IAECluster> modificationInProgress = new WeakReference<>(null);
+
     private final IAEMultiBlock target;
 
     public MBCalculator(final IAEMultiBlock t) {
         this.target = t;
     }
 
-    public void calculateMultiblock(final World world, final WorldCoord loc) {
-        if (Platform.isClient()) {
+    public static void setModificationInProgress(IAECluster cluster) {
+        IAECluster inProgress = modificationInProgress.get();
+        if (inProgress == cluster) {
             return;
         }
+        if (inProgress != null && cluster != null) {
+            throw new IllegalStateException("A modification is already in-progress for: " + inProgress);
+        }
+        modificationInProgress = new WeakReference<>(cluster);
+    }
+
+    public static boolean isModificationInProgress() {
+        return modificationInProgress.get() != null;
+    }
+
+    public void calculateMultiblock(final World world, final WorldCoord loc) {
+        if (Platform.isClient() || isModificationInProgress()) {
+            return;
+        }
+
+        IAECluster currentCluster = target.getCluster();
+        if (currentCluster != null && currentCluster.isDestroyed()) {
+            return; // If we're still part of a cluster that is in the process of being destroyed,
+                    // don't recalc.
+        }
 
         try {
             final WorldCoord min = loc.copy();
@@ -67,6 +92,7 @@ public abstract class MBCalculator {
             if (this.checkMultiblockScale(min, max)) {
                 if (this.verifyUnownedRegion(world, min, max)) {
                     IAECluster c = this.createCluster(world, min, max);
+                    setModificationInProgress(c);
 
                     try {
                         if (!this.verifyInternalStructure(world, min, max)) {
@@ -94,6 +120,8 @@ public abstract class MBCalculator {
             }
         } catch (final Throwable err) {
             AELog.debug(err);
+        } finally {
+            setModificationInProgress(null);
         }
 
         this.disconnect();

src/main/java/appeng/me/cluster/implementations/CraftingCPUCluster.java

@@ -72,6 +72,7 @@ import appeng.crafting.CraftingWatcher;
 import appeng.crafting.MECraftingInventory;
 import appeng.me.cache.CraftingGridCache;
 import appeng.me.cluster.IAECluster;
+import appeng.me.cluster.MBCalculator;
 import appeng.me.helpers.MachineSource;
 import appeng.tile.crafting.CraftingMonitorTileEntity;
 import appeng.tile.crafting.CraftingTileEntity;
@@ -119,6 +120,7 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU {
         this.max = max;
     }
 
+    @Override
     public boolean isDestroyed() {
         return this.isDestroyed;
     }
@@ -162,19 +164,24 @@ public final class CraftingCPUCluster implements IAECluster, ICraftingCPU {
         }
         this.isDestroyed = true;
 
-        boolean posted = false;
+        MBCalculator.setModificationInProgress(this);
+        try {
+            boolean posted = false;
 
-        for (final CraftingTileEntity r : this.tiles) {
-            final IGridNode n = r.getActionableNode();
-            if (n != null && !posted) {
-                final IGrid g = n.getGrid();
-                if (g != null) {
-                    g.postEvent(new MENetworkCraftingCpuChange(n));
-                    posted = true;
+            for (final CraftingTileEntity r : this.tiles) {
+                final IGridNode n = r.getActionableNode();
+                if (n != null && !posted) {
+                    final IGrid g = n.getGrid();
+                    if (g != null) {
+                        g.postEvent(new MENetworkCraftingCpuChange(n));
+                        posted = true;
+                    }
                 }
-            }
 
-            r.updateStatus(null);
+                r.updateStatus(null);
+            }
+        } finally {
+            MBCalculator.setModificationInProgress(null);
         }
     }
 

src/main/java/appeng/me/cluster/implementations/QuantumCluster.java

@@ -40,6 +40,7 @@ import appeng.core.AELog;
 import appeng.core.Api;
 import appeng.me.cache.helpers.ConnectionWrapper;
 import appeng.me.cluster.IAECluster;
+import appeng.me.cluster.MBCalculator;
 import appeng.tile.qnb.QuantumBridgeTileEntity;
 import appeng.util.iterators.ChainedIterator;
 
@@ -189,6 +190,11 @@ public class QuantumCluster implements ILocatable, IAECluster {
         return this.thisSide != 0;
     }
 
+    @Override
+    public boolean isDestroyed() {
+        return isDestroyed;
+    }
+
     @Override
     public void destroy() {
         if (this.isDestroyed) {
@@ -196,24 +202,29 @@ public class QuantumCluster implements ILocatable, IAECluster {
         }
         this.isDestroyed = true;
 
-        if (this.registered) {
-            MinecraftForge.EVENT_BUS.unregister(this);
-            this.registered = false;
+        MBCalculator.setModificationInProgress(this);
+        try {
+            if (this.registered) {
+                MinecraftForge.EVENT_BUS.unregister(this);
+                this.registered = false;
+            }
+
+            if (this.thisSide != 0) {
+                this.updateStatus(true);
+                MinecraftForge.EVENT_BUS.post(new LocatableEventAnnounce(this, LocatableEvent.UNREGISTER));
+            }
+
+            this.center.updateStatus(null, (byte) -1, this.isUpdateStatus());
+
+            for (final QuantumBridgeTileEntity r : this.getRing()) {
+                r.updateStatus(null, (byte) -1, this.isUpdateStatus());
+            }
+
+            this.center = null;
+            this.setRing(new QuantumBridgeTileEntity[8]);
+        } finally {
+            MBCalculator.setModificationInProgress(null);
         }
-
-        if (this.thisSide != 0) {
-            this.updateStatus(true);
-            MinecraftForge.EVENT_BUS.post(new LocatableEventAnnounce(this, LocatableEvent.UNREGISTER));
-        }
-
-        this.center.updateStatus(null, (byte) -1, this.isUpdateStatus());
-
-        for (final QuantumBridgeTileEntity r : this.getRing()) {
-            r.updateStatus(null, (byte) -1, this.isUpdateStatus());
-        }
-
-        this.center = null;
-        this.setRing(new QuantumBridgeTileEntity[8]);
     }
 
     @Override

src/main/java/appeng/me/cluster/implementations/SpatialPylonCluster.java

@@ -25,6 +25,7 @@ import java.util.List;
 import appeng.api.networking.IGridHost;
 import appeng.api.util.DimensionalCoord;
 import appeng.me.cluster.IAECluster;
+import appeng.me.cluster.MBCalculator;
 import appeng.tile.spatial.SpatialPylonTileEntity;
 
 public class SpatialPylonCluster implements IAECluster {
@@ -59,6 +60,11 @@ public class SpatialPylonCluster implements IAECluster {
         }
     }
 
+    @Override
+    public boolean isDestroyed() {
+        return isDestroyed;
+    }
+
     @Override
     public void destroy() {
 
@@ -67,8 +73,13 @@ public class SpatialPylonCluster implements IAECluster {
         }
         this.isDestroyed = true;
 
-        for (final SpatialPylonTileEntity r : this.getLine()) {
-            r.updateStatus(null);
+        MBCalculator.setModificationInProgress(this);
+        try {
+            for (final SpatialPylonTileEntity r : this.getLine()) {
+                r.updateStatus(null);
+            }
+        } finally {
+            MBCalculator.setModificationInProgress(null);
         }
     }