Creating and freeing keys

Manipulating Cached Data 2

• To create a new key:

    mpi_key_create (copyfun, deletefun,
                    keyval, extrastate, ierr)

• copyfun is a callback function used to copy cached attributes when mpi_comm_dup is used to duplicate a communicator.
• deletefun is a delete function used to free cached data when a call is made to either mpi_comm_free or mpi_attr_delete.
• To free a key:

    mpi_key_free (keyval, ierr)