17.2.387. MPI_Type_create_keyval

MPI_Type_create_keyval - Generates a new attribute key for caching on data types.

17.2.387.1. SYNTAX

17.2.387.1.1. C Syntax

#include <mpi.h>

int MPI_Type_create_keyval(MPI_Type_copy_attr_function *type_copy_attr_fn,
     MPI_Type_delete_attr_function *type_delete_attr_fn,
     int *type_keyval, void *extra_state)

17.2.387.1.2. Fortran Syntax (see FORTRAN 77 NOTES)

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_CREATE_KEYVAL(TYPE_COPY_ATTR_FN, TYPE_DELETE_ATTR_FN,
             TYPE_KEYVAL, EXTRA_STATE, IERROR)
     EXTERNAL TYPE_COPY_ATTR_FN, TYPE_DELETE_ATTR_FN
     INTEGER TYPE_KEYVAL, IERROR
     INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE

17.2.387.1.3. Fortran 2008 Syntax

USE mpi_f08
MPI_Type_create_keyval(type_copy_attr_fn, type_delete_attr_fn, type_keyval,
             extra_state, ierror)
     PROCEDURE(MPI_Type_copy_attr_function) :: type_copy_attr_fn
     PROCEDURE(MPI_Type_delete_attr_function) :: type_delete_attr_fn
     INTEGER, INTENT(OUT) :: type_keyval
     INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: extra_state
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

17.2.387.2. INPUT PARAMETERS

type_copy_attr_fn: Copy callback function for type_keyval (function).
type_delete_attr_fn: Delete callback function for type_keyval (function).
extra_state: Extra state for callback functions.

17.2.387.3. OUTPUT PARAMETERS

type_keyval: Key value for future access (integer).
IERROR: Fortran only: Error status (integer).

17.2.387.4. DESCRIPTION

MPI_Type_create_keyval generates a new attribute key for caching on data types. This routine partially replaces MPI_Keyval_create.

The argument type_copy_attr_fn may be specified as MPI_TYPE_NULL_COPY_FN or MPI_TYPE_DUP_FN from C or Fortran. MPI_TYPE_NULL_COPY_FN is a function that does nothing other than returning flag = 0 and MPI_SUCCESS. MPI_TYPE_DUP_FN is a simple-minded copy function that sets flag = 1, returns the value of attribute_val_in in attribute_val_out, and returns MPI_SUCCESS.

The argument type_delete_attr_fn may be specified as MPI_TYPE_NULL_DELETE_FN from C or Fortran. MPI_TYPE_NULL_DELETE_FN is a function that does nothing beyond returning MPI_SUCCESS. The C callback functions are:

typedef int MPI_Type_copy_attr_function(MPI_Datatype oldtype,
            int type_keyval, void *extra_state, void *attribute_val_in,
            void *attribute_val_out, int *flag);

and

typedef int MPI_Type_delete_attr_function(MPI_Datatype type, int type_keyval,
             void *attribute_val, void *extra_state);

The Fortran callback functions are:

SUBROUTINE TYPE_COPY_ATTR_FN(OLDTYPE, TYPE_KEYVAL, EXTRA_STATE,
             ATTRIBUTE_VAL_IN, ATTRIBUTE_VAL_OUT, FLAG, IERROR)
    INTEGER OLDTYPE, TYPE KEYVAL, IERROR
    INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE,
        ATTRIBUTE_VAL_IN, ATTRIBUTE_VAL_OUT
    LOGICAL FLAG

and

SUBROUTINE TYPE_DELETE_ATTR_FN(TYPE, TYPE_KEYVAL, ATTRIBUTE_VAL, EXTRA_STATE,
             IERROR)
    INTEGER TYPE, TYPE_KEYVAL, IERROR
    INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE VAL, EXTRA_STATE

17.2.387.5. FORTRAN 77 NOTES

The MPI standard prescribes portable Fortran syntax for the EXTRA_STATE argument only for Fortran 90. FORTRAN 77 users may use the non-portable syntax

INTEGER*MPI_ADDRESS_KIND EXTRA_STATE

where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of the declared integer in bytes.

17.2.387.6. ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.