'Finalize put by renaming the object data file to include a durable
marker. We do this for EC policy because it requires a 2-phase put
commit confirmation.
:param timestamp: object put timestamp, an instance of
:class:`~swift.common.utils.Timestamp`
:raises DiskFileError: if the diskfile frag_index has not been set
(either during initialisation or a call to put())'

def commit(self, timestamp):

    data_file_path = join(self._datadir, self.manager.make_on_disk_filename(timestamp, '.data', self._diskfile._frag_index))
    durable_data_file_path = os.path.join(self._datadir, self.manager.make_on_disk_filename(timestamp, '.data', self._diskfile._frag_index, durable=True))
    tpool_reraise(self._finalize_durable, data_file_path, durable_data_file_path)
