def resources(self):
        ''' get total resources and available ones '''
        used_resources = self._used_resources()
        ret = collections.defaultdict(dict)
        for resource, total in six.iteritems(self._resources):
            ret[resource]['total'] = total
            if resource in used_resources:
                ret[resource]['used'] = used_resources[resource]
            else:
                ret[resource]['used'] = 0
        return ret
get total resources and available ones