fix crash on 'llen' while list is not exist
fix crash on 'llen' while list is not exist

wfxiang08/ardb,tempbottle/ardb,yinqiwen/ardb,cloudrain21/ardb,tempbottle/ardb,lsm/ardb,bssrdf/ardb,lsm/ardb,spitfire2/ardb,placrosse/ardb,spitfire2/ardb,bssrdf/ardb,yinqiwen/ardb,placrosse/ardb,wfxiang08/ardb,cloudrain21/ardb