I deployed a sharding cluster with 4 replica sets. Each rs contains a primary and a secondary and an arbiter. I insert data into primary and make queries on secondaries by using read preferrence "SecondaryPreferred".
However, in some circumstance，my secondaries lag behind for a long time(eg. serveral hours) because of heavy load or hardware maintenance. In this circumstance, I actually don't want my app to read data from secondries becuse data in them are quite old. I prefer them to read from primary instead.

So. Is it possible to add a config to specify a value, when the secondary find that it's
behind more than this time span, it will turn to a "CATCH UP" status so that it's not a valid node temporary. And then "SecondaryPreferred" reads will be routed to primaries.