Every DB Call opens a session, and then closes it

KthfsDBCalls.java

public static BlockInfo getBlockInfo(long blockId)  {
		int tries = RETRY_COUNT;
		boolean done = false;
		Session session = DBConnector.sessionFactory.getSession(); //Gets a session
		Transaction tx = session.currentTransaction(); //Starts transaction
		while (done == false && tries > 0) {
			try {
				tx.begin();
				BlockInfo ret = getBlockInfoInternal(blockId, session, false);
				tx.commit();
				session.flush();
				done=true;
				return ret;
			}
			catch (ClusterJException e){
				tx.rollback();
				System.err.println("getBlockInfo failed " + e.getMessage());
				tries--;
			}
			finally {
				session.close ();
			}
		}
		return null;