623         self._nodecache = {nullid: nullrev}

   623         self._nodecache = {nullid: nullrev}

   624         self._nodepos = None

   624         self._nodepos = None

   625         self._compengine = 'zlib'

   625         self._compengine = 'zlib'

   626         self._maxdeltachainspan = -1

   626         self._maxdeltachainspan = -1

   627         self._withsparseread = False

   627         self._withsparseread = False

   629         self._srmingapsize = 262144

   629         self._srmingapsize = 262144

   630 

   630 

   631         mmapindexthreshold = None

   631         mmapindexthreshold = None

   632         v = REVLOG_DEFAULT_VERSION

   632         v = REVLOG_DEFAULT_VERSION

   633         opts = getattr(opener, 'options', None)

   633         opts = getattr(opener, 'options', None)