Moved dangerous helper methods out of AVMService.

Reworked handling of path lookup failures to not throw exceptions
internally, to improve performance of certain layered directory
operations.  Unfortunately there remains at least one scenario,
handling of bulk loads, and promotions of deeply nested directories in
layered contexts, in which performance is considerably less than
ideal. 

Made AVMService.createBranch() and AVMSyncService.update() perform
implicit snapshots of source tree's stores before proceeding.


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/BRANCHES/WCM-DEV2/root@3812 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/avm/AVMRepository.java

@@ -105,8 +105,12 @@ public class AVMRepository
     {
         fLookupCount.set(1);
         String[] pathParts = SplitPath(path);
-        AVMStore rep = getAVMStoreByName(pathParts[0]);
-        return rep.createFile(pathParts[1], name);
+        AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        return store.createFile(pathParts[1], name);
     }
 
     /**
@@ -119,8 +123,12 @@ public class AVMRepository
     {
         fLookupCount.set(1);
         String[] pathParts = SplitPath(path);
-        AVMStore rep = getAVMStoreByName(pathParts[0]);
-        rep.createFile(pathParts[1], name, data);
+        AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        store.createFile(pathParts[1], name, data);
     }
     
     /**
@@ -132,8 +140,12 @@ public class AVMRepository
     {
         fLookupCount.set(1);
         String[] pathParts = SplitPath(path);
-        AVMStore rep = getAVMStoreByName(pathParts[0]);
-        rep.createDirectory(pathParts[1], name);
+        AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        store.createDirectory(pathParts[1], name);
     }
 
     /**
@@ -157,6 +169,10 @@ public class AVMRepository
         // We need the store to do anything so...
         String [] pathParts = SplitPath(parent.getPath());
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         DirectoryNode dir = (DirectoryNode)node;
         DirectoryNode child = null;
         if (dir instanceof LayeredDirectoryNode)
@@ -188,9 +204,12 @@ public class AVMRepository
         }
         fLookupCount.set(1);
         String[] pathParts = SplitPath(dstPath);
-        AVMStore rep = getAVMStoreByName(pathParts[0]);
-//        fSession.get().lock(rep, LockMode.UPGRADE);
-        rep.createLayeredDirectory(srcPath, pathParts[1], name);
+        AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        store.createLayeredDirectory(srcPath, pathParts[1], name);
     }
 
     /**
@@ -203,8 +222,12 @@ public class AVMRepository
     {
         fLookupCount.set(1);
         String[] pathParts = SplitPath(dstPath);
-        AVMStore rep = getAVMStoreByName(pathParts[0]);
-        rep.createLayeredFile(srcPath, pathParts[1], name);
+        AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        store.createLayeredFile(srcPath, pathParts[1], name);
     }
 
     /**
@@ -213,15 +236,10 @@ public class AVMRepository
      */
     public void createAVMStore(String name)
     {
-        try
+        if (getAVMStoreByName(name) != null)
         {
-            getAVMStoreByName(name);
             throw new AVMExistsException("AVMStore exists: " + name);
         }
-        catch (AVMNotFoundException anf)
-        {
-            // Do nothing.
-        }
         // Newing up the object causes it to be written to the db.
         @SuppressWarnings("unused") 
         AVMStore rep = new AVMStoreImpl(this, name);
@@ -246,12 +264,32 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(srcPath);
         AVMStore srcRepo = getAVMStoreByName(pathParts[0]);
+        if (srcRepo == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        if (version < 0)
+        {
+            version = srcRepo.createSnapshot();
+        }
         Lookup sPath = srcRepo.lookup(version, pathParts[1], false, false);
+        if (sPath == null)
+        {
+            throw new AVMNotFoundException("Path not found.");
+        }
         // Lookup the destination directory.
         fLookupCount.set(1);
         pathParts = SplitPath(dstPath);
         AVMStore dstRepo = getAVMStoreByName(pathParts[0]);
+        if (dstRepo == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         Lookup dPath = dstRepo.lookupDirectory(-1, pathParts[1], true);
+        if (dPath == null)
+        {
+            throw new AVMNotFoundException("Path not found.");
+        }
         DirectoryNode dirNode = (DirectoryNode)dPath.getCurrentNode();
         AVMNode srcNode = sPath.getCurrentNode();
         AVMNode dstNode = null;
@@ -291,8 +329,12 @@ public class AVMRepository
     {
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
-        AVMStore rep = getAVMStoreByName(pathParts[0]);
-        return rep.getOutputStream(pathParts[1]);
+        AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        return store.getOutputStream(pathParts[1]);
     }
     
     /**
@@ -313,7 +355,15 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(srcPath);
         AVMStore srcRepo = getAVMStoreByName(pathParts[0]);
+        if (srcRepo == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         Lookup sPath = srcRepo.lookupDirectory(-1, pathParts[1], true);
+        if (sPath == null)
+        {
+            throw new AVMNotFoundException("Path not found.");
+        }
         DirectoryNode srcDir = (DirectoryNode)sPath.getCurrentNode();
         AVMNode srcNode = srcDir.lookupChild(sPath, srcName, -1, true, false);
         if (srcNode == null)
@@ -323,7 +373,15 @@ public class AVMRepository
         fLookupCount.set(1);
         pathParts = SplitPath(dstPath);
         AVMStore dstRepo = getAVMStoreByName(pathParts[0]);
+        if (dstRepo == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         Lookup dPath = dstRepo.lookupDirectory(-1, pathParts[1], true);
+        if (dPath == null)
+        {
+            throw new AVMNotFoundException("Path not found.");
+        }
         DirectoryNode dstDir = (DirectoryNode)dPath.getCurrentNode();
         AVMNode dstNode = dstDir.lookupChild(dPath, dstName, -1, true, false);
         if (dstNode != null)
@@ -425,8 +483,12 @@ public class AVMRepository
     {
         fLookupCount.set(1);
         String [] pathParts = SplitPath(dirPath);
-        AVMStore repo = getAVMStoreByName(pathParts[0]);
-        repo.uncover(pathParts[1], name);
+        AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        store.uncover(pathParts[1], name);
     }
 
     /**
@@ -439,8 +501,12 @@ public class AVMRepository
         List<Integer> result = new ArrayList<Integer>();
         for (String repName : repositories)
         {
-            AVMStore repo = getAVMStoreByName(repName);
-            result.add(repo.createSnapshot());
+            AVMStore store = getAVMStoreByName(repName);
+            if (store == null)
+            {
+                throw new AVMNotFoundException("Store not found.");
+            }
+            result.add(store.createSnapshot());
         }
         return result;
     }
@@ -453,6 +519,10 @@ public class AVMRepository
     public int createSnapshot(String storeName)
     {
         AVMStore store = getAVMStoreByName(storeName);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.createSnapshot();
     }
 
@@ -466,6 +536,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }        
         store.removeNode(pathParts[1], name);
     }
 
@@ -478,6 +552,10 @@ public class AVMRepository
     public void purgeAVMStore(String name)
     {
         AVMStore store = getAVMStoreByName(name);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         AVMNode root = store.getRoot();
         root.setIsRoot(false);
         VersionRootDAO vrDAO = AVMContext.fgInstance.fVersionRootDAO;
@@ -505,6 +583,10 @@ public class AVMRepository
     public void purgeVersion(String name, int version)
     {
         AVMStore store = getAVMStoreByName(name);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.purgeVersion(version);
     }
 
@@ -519,6 +601,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getInputStream(version, pathParts[1]);
     }
 
@@ -535,6 +621,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getListing(version, pathParts[1], includeDeleted);
     }
 
@@ -550,6 +640,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getListingDirect(version, pathParts[1], includeDeleted);
     }
     
@@ -612,6 +706,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getDeleted(version, pathParts[1]);
     }
     
@@ -639,6 +737,10 @@ public class AVMRepository
     public AVMStoreDescriptor getAVMStore(String name)
     {
         AVMStore store = getAVMStoreByName(name);
+        if (store == null)
+        {
+            return null;
+        }
         return store.getDescriptor();
     }
     
@@ -650,6 +752,10 @@ public class AVMRepository
     public List<VersionDescriptor> getAVMStoreVersions(String name)
     {
         AVMStore store = getAVMStoreByName(name);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getVersions();
     }
 
@@ -664,6 +770,10 @@ public class AVMRepository
     public List<VersionDescriptor> getAVMStoreVersions(String name, Date from, Date to)
     {
         AVMStore store = getAVMStoreByName(name);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getVersions(from, to);
     }
     
@@ -696,6 +806,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getIndirectionPath(version, pathParts[1]);
     }
 
@@ -707,6 +821,10 @@ public class AVMRepository
     public int getLatestVersionID(String name)
     {
         AVMStore store = getAVMStoreByName(name);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getNextVersionID();
     }
     
@@ -717,12 +835,7 @@ public class AVMRepository
      */
     private AVMStore getAVMStoreByName(String name)
     {
-        AVMStore store = AVMContext.fgInstance.fAVMStoreDAO.getByName(name);
-        if (store == null)
-        {
-            throw new AVMNotFoundException("AVMStore not found: " + name);
-        }
-        return store;
+        return AVMContext.fgInstance.fAVMStoreDAO.getByName(name);
     }
 
     /**
@@ -768,8 +881,11 @@ public class AVMRepository
             }
             String [] pathParts = SplitPath(path);
             AVMStore store = getAVMStoreByName(pathParts[0]);
-            Lookup result = store.lookup(version, pathParts[1], false, includeDeleted);
-            return result;
+            if (store == null)
+            {
+                return null;
+            }
+            return store.lookup(version, pathParts[1], false, includeDeleted);
         }
         finally
         {
@@ -780,6 +896,7 @@ public class AVMRepository
         }
     }
     
+    // TODO This should really return null for not found.
     /**
      * Lookup a descriptor from a directory descriptor.
      * @param dir The directory descriptor.
@@ -814,7 +931,15 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         Lookup lookup = store.lookup(version, pathParts[1], false, false);
+        if (lookup == null)
+        {
+            throw new AVMNotFoundException("Path not found.");
+        }
         return new LayeringDescriptor(!lookup.getDirectlyContained(),
                                       lookup.getAVMStore().getDescriptor(),
                                       lookup.getFinalStore().getDescriptor());
@@ -834,6 +959,10 @@ public class AVMRepository
         }
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            return null;
+        }
         return store.lookupDirectory(version, pathParts[1], false);
     }
 
@@ -861,6 +990,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String[] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.makePrimary(pathParts[1]);
     }
 
@@ -874,6 +1007,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String[] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.retargetLayeredDirectory(pathParts[1], target);
     }
     
@@ -918,6 +1055,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String[] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.setOpacity(pathParts[1], opacity);
     }
         
@@ -932,6 +1073,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.setNodeProperty(pathParts[1], name, value);
     }
     
@@ -945,6 +1090,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.setNodeProperties(pathParts[1], properties);
     }
     
@@ -960,6 +1109,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getNodeProperty(version, pathParts[1], name);
     }
     
@@ -974,6 +1127,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getNodeProperties(version, pathParts[1]);
     }
     
@@ -987,6 +1144,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.deleteNodeProperty(pathParts[1], name);
     }
 
@@ -999,6 +1160,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.deleteNodeProperties(pathParts[1]);
     }
     
@@ -1010,7 +1175,12 @@ public class AVMRepository
      */
     public void setStoreProperty(String store, QName name, PropertyValue value)
     {
-        getAVMStoreByName(store).setProperty(name, value);
+        AVMStore st = getAVMStoreByName(store);
+        if (st == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        st.setProperty(name, value);
     }
     
     /**
@@ -1020,7 +1190,12 @@ public class AVMRepository
      */
     public void setStoreProperties(String store, Map<QName, PropertyValue> props)
     {
-        getAVMStoreByName(store).setProperties(props);
+        AVMStore st = getAVMStoreByName(store);
+        if (st == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        st.setProperties(props);
     }
     
     /**
@@ -1031,7 +1206,16 @@ public class AVMRepository
      */
     public PropertyValue getStoreProperty(String store, QName name)
     {
-        return getAVMStoreByName(store).getProperty(name);
+        if (store == null)
+        {
+            throw new AVMBadArgumentException("Null store name.");
+        }
+        AVMStore st = getAVMStoreByName(store);
+        if (st == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        return st.getProperty(name);
     }
     
     /**
@@ -1042,8 +1226,13 @@ public class AVMRepository
      */
     public Map<QName, PropertyValue> queryStorePropertyKey(String store, QName keyPattern)
     {
+        AVMStore st = getAVMStoreByName(store);
+        if (st == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         List<AVMStoreProperty> matches =
-            AVMContext.fgInstance.fAVMStorePropertyDAO.queryByKeyPattern(getAVMStoreByName(store),
+            AVMContext.fgInstance.fAVMStorePropertyDAO.queryByKeyPattern(st,
                                                                          keyPattern);
         Map<QName, PropertyValue> results = new HashMap<QName, PropertyValue>();
         for (AVMStoreProperty prop : matches)
@@ -1086,7 +1275,16 @@ public class AVMRepository
      */
     public Map<QName, PropertyValue> getStoreProperties(String store)
     {
-        return getAVMStoreByName(store).getProperties();
+        if (store == null)
+        {
+            throw new AVMBadArgumentException("Null store name.");
+        }
+        AVMStore st = getAVMStoreByName(store);
+        if (st == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        return st.getProperties();
     }
     
     /**
@@ -1096,17 +1294,12 @@ public class AVMRepository
      */
     public void deleteStoreProperty(String store, QName name)
     {
-        getAVMStoreByName(store).deleteProperty(name);
-    }
-    
-    /**
-     * Get the AVMStoreDescriptor for an AVMStore.
-     * @param name The name of the AVMStore.
-     * @return The descriptor.
-     */
-    public AVMStoreDescriptor getAVMStoreDescriptor(String name)
-    {
-        return getAVMStoreByName(name).getDescriptor();
+        AVMStore st = getAVMStoreByName(store);
+        if (st == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
+        st.deleteProperty(name);
     }
     
     /**
@@ -1179,6 +1372,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getContentDataForWrite(pathParts[1]);
     }
 
@@ -1192,6 +1389,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }        
         store.setContentData(pathParts[1], data);
     }
     
@@ -1214,6 +1415,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.addAspect(pathParts[1], aspectName);
     }
     
@@ -1228,6 +1433,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getAspects(version, pathParts[1]);
     }
     
@@ -1241,6 +1450,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.removeAspect(pathParts[1], aspectName);
     }
     
@@ -1256,6 +1469,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.hasAspect(version, pathParts[1], aspectName);
     }
     
@@ -1269,6 +1486,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.setACL(pathParts[1], acl);
     }
     
@@ -1283,6 +1504,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         return store.getACL(version, pathParts[1]);
     }
     
@@ -1297,6 +1522,10 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(parentPath);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         store.link(pathParts[1], name, toLink);
     }
     
@@ -1353,8 +1582,16 @@ public class AVMRepository
         fLookupCount.set(1);
         String [] pathParts = SplitPath(path);
         AVMStore store = getAVMStoreByName(pathParts[0]);
+        if (store == null)
+        {
+            throw new AVMNotFoundException("Store not found.");
+        }
         // Just force a copy if needed by looking up in write mode.
         Lookup lPath = store.lookup(-1, pathParts[1], true, false);
+        if (lPath == null)
+        {
+            throw new AVMNotFoundException("Path not found.");
+        }
         AVMNode node = lPath.getCurrentNode();
         return node.getDescriptor(lPath);
     }