Class NodeManager

java.lang.Object
helma.objectmodel.db.NodeManager

public final class NodeManager extends Object
The NodeManager is responsible for fetching Nodes from the internal or external data sources, caching them in a least-recently-used Hashtable, and writing changes back to the databases.
  • Field Details

  • Constructor Details

    • NodeManager

      public NodeManager(Application app)
      Create a new NodeManager for Application app.
  • Method Details

    • init

      Initialize the NodeManager for the given dbHome and application properties. An embedded database will be created in dbHome if one doesn't already exist.
      Throws:
      DatabaseException
      ClassNotFoundException
      IllegalAccessException
      InstantiationException
    • getRootNode

      public Node getRootNode() throws Exception
      Gets the application's root node.
      Throws:
      Exception
    • isRootNode

      public boolean isRootNode(Node node)
      Checks if the given node is the application's root node.
    • updateProperties

      public void updateProperties(Properties props)
      app.properties file has been updated. Reread some settings.
    • shutdown

      public void shutdown() throws DatabaseException
      Shut down this node manager. This is called when the application using this node manager is stopped.
      Throws:
      DatabaseException
    • deleteNode

      public void deleteNode(Node node) throws Exception
      Delete a node from the database.
      Throws:
      Exception
    • getNode

      public Node getNode(Key key) throws Exception
      Get a node by key. This is called from a node that already holds a reference to another node via a NodeHandle/Key.
      Throws:
      Exception
    • getNode

      public Node getNode(Node home, String kstr, Relation rel) throws Exception
      Get a node by relation, using the home node, the relation and a key to apply. In contrast to getNode (Key key), this is usually called when we don't yet know whether such a node exists.
      Throws:
      Exception
    • registerNode

      public void registerNode(Node node)
      Register a node in the node cache.
    • registerNode

      protected void registerNode(Node node, Key key)
      Register a node in the node cache using the key argument.
    • evictNode

      public void evictNode(Node node)
      Remove a node from the node cache. If at a later time it is accessed again, it will be refetched from the database.
    • evictNodeByKey

      public void evictNodeByKey(Key key)
      Remove a node from the node cache. If at a later time it is accessed again, it will be refetched from the database.
    • evictKey

      public void evictKey(Key key)
      Used when a key stops being valid for a node. The cached node itself remains valid, if it is present in the cache by other keys.
    • insertNode

      public void insertNode(IDatabase db, ITransaction txn, Node node) throws IOException, SQLException, ClassNotFoundException
      Insert a new node in the embedded database or a relational database table, depending on its db mapping.
      Throws:
      IOException
      SQLException
      ClassNotFoundException
    • exportNode

      public void exportNode(Node node, DbSource dbs) throws SQLException, ClassNotFoundException
      Insert a node into a different (relational) database than its default one.
      Throws:
      SQLException
      ClassNotFoundException
    • exportNode

      public void exportNode(Node node, DbMapping dbm) throws SQLException, ClassNotFoundException
      Insert a node into a different (relational) database than its default one.
      Throws:
      SQLException
      ClassNotFoundException
    • insertRelationalNode

      protected void insertRelationalNode(Node node, DbMapping dbm, Connection con) throws ClassNotFoundException, SQLException
      Insert a node into a relational database.
      Throws:
      ClassNotFoundException
      SQLException
    • updateNode

      public boolean updateNode(IDatabase db, ITransaction txn, Node node) throws IOException, SQLException, ClassNotFoundException
      Updates a modified node in the embedded db or an external relational database, depending on its database mapping.
      Returns:
      true if the DbMapping of the updated Node is to be marked as updated via DbMapping.setLastDataChange
      Throws:
      IOException
      SQLException
      ClassNotFoundException
    • deleteNode

      public void deleteNode(IDatabase db, ITransaction txn, Node node) throws Exception
      Performs the actual deletion of a node from either the embedded or an external SQL database.
      Throws:
      Exception
    • generateID

      public String generateID(DbMapping map) throws Exception
      Generate a new ID for a given type, delegating to our IDGenerator if set.
      Throws:
      Exception
    • doGenerateID

      public String doGenerateID(DbMapping map) throws Exception
      Actually generates an ID, using a method matching the given DbMapping.
      Throws:
      Exception
    • getNodeIDs

      public List getNodeIDs(Node home, Relation rel) throws Exception
      Loades subnodes via subnode relation. Only the ID index is loaded, the nodes are loaded later on demand.
      Throws:
      Exception
    • getNodes

      public List getNodes(Node home, Relation rel) throws Exception
      Loades subnodes via subnode relation. This is similar to getNodeIDs, but it actually loades all nodes in one go, which is better for small node collections. This method is used when xxx.loadmode=aggressive is specified.
      Throws:
      Exception
    • collectMissingKeys

      protected List collectMissingKeys(SubnodeList list, int start, int length)
    • prefetchNodes

      public void prefetchNodes(Node home, Relation rel, SubnodeList list, int start, int length) throws Exception
      Throws:
      Exception
    • countNodes

      public int countNodes(Node home, Relation rel) throws Exception
      Count the nodes contained in the child collection of the home node which is defined by Relation rel.
      Throws:
      Exception
    • getPropertyNames

      public Vector getPropertyNames(Node home, Relation rel) throws Exception
      Similar to getNodeIDs, but returns a List that contains the nodes property names instead of IDs
      Throws:
      Exception
    • createNode

      public Node createNode(DbMapping dbm, ResultSet rs, DbColumn[] columns, int offset) throws SQLException, IOException, ClassNotFoundException
      Create a new Node from a ResultSet.
      Throws:
      SQLException
      IOException
      ClassNotFoundException
    • getDbMapping

      public DbMapping getDbMapping(String protoname)
      Get a DbMapping for a given prototype name. This is just a proxy method to the app's getDbMapping() method.
    • getCacheEntries

      public Object[] getCacheEntries()
      Get an array of the the keys currently held in the object cache
    • countCacheEntries

      public int countCacheEntries()
      Get the number of elements in the object cache
    • clearCache

      public void clearCache()
      Clear the object cache, causing all objects to be recreated.
    • getCacheStatistics

      public Map getCacheStatistics()
      Returns a map with statistics about the cache
    • addNodeChangeListener

      public void addNodeChangeListener(NodeChangeListener listener)
      Add a listener that is notified each time a transaction commits that adds, modifies or deletes any Nodes.
    • removeNodeChangeListener

      public void removeNodeChangeListener(NodeChangeListener listener)
      Remove a previously added NodeChangeListener.
    • hasNodeChangeListeners

      protected boolean hasNodeChangeListeners()
      Let transactors know if they should collect and fire NodeChangeListener events
    • fireNodeChangeEvent

      protected void fireNodeChangeEvent(List inserted, List updated, List deleted, List parents)
      Called by transactors after committing.