DB_LOCK_NOWAIT
__db_fchk(lt->dbenv, "lock_vec", flags, DB_LOCK_NOWAIT)) != 0)
"lock_get", flags, DB_LOCK_NOWAIT | DB_LOCK_UPGRADE)) != 0)
"lock_get", flags, DB_LOCK_NOWAIT | DB_LOCK_UPGRADE)) != 0)
else if (!(flags & DB_LOCK_NOWAIT))