MPI_Comm_create_keyval(3) Open MPI MPI_Comm_create_keyval(3)
NAME
MPI_Comm_create_keyval - Generates a new attribute key.
SYNTAX
C Syntax
#include <mpi.h>
int MPI_Comm_create_keyval(MPI_Comm_copy_attr_function
*comm_copy_attr_fn, MPI_Comm_delete_attr_function
*comm_delete_attr_fn, int *comm_keyval,
void *extra_state)
Fortran Syntax (see FORTRAN 77 NOTES)
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_CREATE_KEYVAL(COMM_COPY_ATTR_FN, COMM_DELETE_ATTR_FN,
COMM_KEYVAL, EXTRA_STATE, IERROR)
EXTERNAL COMM_COPY_ATTR_FN, COMM_DELETE_ATTR_FN
INTEGER COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE
Fortran 2008 Syntax
USE mpi_f08
MPI_Comm_create_keyval(comm_copy_attr_fn, comm_delete_attr_fn, comm_keyval,
extra_state, ierror)
PROCEDURE(MPI_Comm_copy_attr_function) :: comm_copy_attr_fn
PROCEDURE(MPI_Comm_delete_attr_function) :: comm_delete_attr_fn
INTEGER, INTENT(OUT) :: comm_keyval
INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: extra_state
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
C++ Syntax
#include <mpi.h>
static in MPI::Comm::Create_keyval(MPI::Comm::Copy_attr_function*
comm_copy_attr_fn,
MPI::Comm::Delete_attr_function* comm_delete_attr_fn,
void* extra_state)
INPUT PARAMETERS
comm_copy_attr_fn
Copy callback function for comm_keyval (function).
comm_delete_attr_fn
Delete callback function for comm_keyval (function).
extra_state
Extra state for callback functions.
OUTPUT PARAMETER
comm_keyval
Key value for future access (integer).
IERROR Fortran only: Error status (integer).
DESCRIPTION
This function replaces MPI_Keyval_create, the use of which is depre-
cated. The C binding is identical. The Fortran binding differs in that
extra_state is an address-sized integer. Also, the copy and delete
callback functions have Fortran bindings that are consistent with ad-
dress-sized attributes.
The argument comm_copy_attr_fn may be specified as
MPI_COMM_NULL_COPY_FN or MPI_COMM_DUP_FN from C, C++, or Fortran.
MPI_COMM_NULL_COPY_FN is a function that does nothing more than return-
ing flag = 0 and MPI_SUCCESS. MPI_COMM_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. These replace the MPI-1
predefined callbacks MPI_NULL_COPY_FN and MPI_DUP_FN, the use of which
is deprecated.
The C callback functions are:
typedef int MPI_Comm_copy_attr_function(MPI_Comm oldcomm, int comm_keyval,
void *extra_state, void *attribute_val_in,
void *attribute_val_out, int *flag);
and
typedef int MPI_Comm_delete_attr_function(MPI_Comm comm, int comm_keyval,
void *attribute_val, void *extra_state);
which are the same as the MPI-1.1 calls but with a new name. The old
names are deprecated.
The Fortran callback functions are:
SUBROUTINE COMM_COPY_ATTR_FN(OLDCOMM, COMM_KEYVAL, EXTRA_STATE,
ATTRIBUTE_VAL_IN, ATTRIBUTE_VAL_OUT, FLAG, IERROR)
INTEGER OLDCOMM, COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE, ATTRIBUTE_VAL_IN,
ATTRIBUTE_VAL_OUT
LOGICAL FLAG
and
SUBROUTINE COMM_DELETE_ATTR_FN(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, EXTRA_STATE,
IERROR)
INTEGER COMM, COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL, EXTRA_STATE
The C++ callbacks are:
typedef int MPI::Comm::Copy_attr_function(const MPI::Comm& oldcomm,
int comm_keyval, void* extra_state, void* attribute_val_in,
void* attribute_val_out, bool& flag);
and
typedef int MPI::Comm::Delete_attr_function(MPI::Comm& comm,
int comm_keyval, void* attribute_val, void* extra_state);
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.
ERRORS
Almost all MPI routines return an error value; C routines as the value
of the function and Fortran routines in the last argument. C++ func-
tions do not return errors. If the default error handler is set to
MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
will be used to throw an MPI::Exception object.
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.
See the MPI man page for a full list of MPI error codes.
SEE ALSO
4.1.2 Nov 24, 2021 MPI_Comm_create_keyval(3)
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