'Return age of data cached at `name` in seconds or 0 if
cache doesn\'t exist
:param name: name of datastore
:type name: ``unicode``
:returns: age of datastore in seconds
:rtype: ``int``'

def cached_data_age(self, name):

    cache_path = self.cachefile((u'%s.%s' % (name, self.cache_serializer)))
    if (not os.path.exists(cache_path)):
        return 0
    return (time.time() - os.stat(cache_path).st_mtime)
