allow empty messages in exchange routines
redists should be able to pass emtpy messages (struct Xt_redist_msg; with datatype = MPI_DATATYPE_NULL and rank = -1) to exchange routines.
These messages are just "place-holders" and should not trigger an actual exchange.
This should result in simple but general exchange routines that supports various message orders.
Updated by Moritz Hanke about 9 years ago
- Status changed from New to Closed
Instead of allowing empty message I introduced a new datatype: xt_exchange. It stores the information required to do the exchange and optimises it. Depending on the optimisation, the required information can be stored accordingly. This way no empty messages are needed.