code: public void getAndSetNodeDataSize(String nodePath)
     {
        try
        {
           long dataSize = getNodeDataSizeDirectly(nodePath);
           quotaPersister.setNodeDataSizeIfQuotaExists(rName, wsName, nodePath, dataSize);
        }
        catch (QuotaManagerException e)
        {
           LOG.warn("Can't calculate node data size " + nodePath + " because: " + e.getCause().getMessage());
        }
     }
docs: Calculates node data size directly and persists value into {@link QuotaPersister}.