plucky (3) MPI_Type_get_envelope.openmpi.3.gz
SYNTAX
C Syntax
#include <mpi.h>
int MPI_Type_get_envelope(MPI_Datatype datatype, int *num_integers,
int *num_addresses, int *num_datatypes, int *combiner)
Fortran Syntax
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_GET_ENVELOPE(DATATYPE, NUM_INTEGERS, NUM_ADDRESSES,
NUM_DATATYPES, COMBINER, IERROR)
INTEGER DATATYPE, NUM_INTEGERS, NUM_ADDRESSES
INTEGER NUM_DATATYPES, COMBINER, IERROR
Fortran 2008 Syntax
USE mpi_f08
MPI_Type_get_envelope(datatype, num_integers, num_addresses, num_datatypes,
combiner, ierror)
TYPE(MPI_Datatype), INTENT(IN) :: datatype
INTEGER, INTENT(OUT) :: num_integers, num_addresses, num_datatypes,
combiner
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
INPUT PARAMETER
• datatype: Data type to access (handle).
OUTPUT PARAMETERS
• num_integers: Number of input integers used in the call constructing combiner (nonnegative integer).
• num_addresses: Number of input addresses used in the call constructing combiner (nonnegative integer).
• num_datatypes: Number of input data types used in the call constructing combiner (nonnegative integer).
• combiner: Combiner (state).
• ierror: Fortran only: Error status (integer).
DESCRIPTION
For the given data type, MPI_Type_get_envelope returns information on the number and type of input
arguments used in the call that created the data type. The number-of-arguments values returned can be
used to provide sufficiently large arrays in the decoding routine MPI_Type_get_contents. This call and
the meaning of the returned values is described below. The combiner reflects the MPI data type
constructor call that was used in creating datatype.
NOTES
These are the values that can be returned in combiner and their associated calls:
Values Associated Calls
MPI_COMBINER_NAMED a named predefined data type
MPI_COMBINER_DUP MPI_Type_dup
MPI_COMBINER_CONTIGUOUS MPI_Type_contiguous
MPI_COMBINER_VECTOR MPI_Type_vector
MPI_COMBINER_HVECTOR MPI_Type_hvector
and MPI_Type_create_hvector
MPI_COMBINER_INDEXED MPI_Type_indexed
MPI_COMBINER_HINDEXED MPI_Type_hindexed
and MPI_Type_create_hindexed
MPI_COMBINER_INDEXED_BLOCK MPI_Type_create_indexed_block
MPI_COMBINER_STRUCT MPI_Type_struct
and MPI_Type_create_struct
MPI_COMBINER_SUBARRAY MPI_Type_create_subarray
MPI_COMBINER_DARRAY MPI_Type_create_darray
MPI_COMBINER_F90_REAL MPI_Type_create_f90_real
MPI_COMBINER_F90_COMPLEX MPI_Type_create_f90_complex
MPI_COMBINER_F90_INTEGER MPI_Type_create_f90_integer
MPI_COMBINER_RESIZED MPI_Type_create_resized
If combiner is MPI_COMBINER_NAMED, then datatype is a named predefined data type.
The actual arguments used in the creation call for a data type can be obtained from the call
MPI_Type_get_contents.
ERRORS
Almost all MPI routines return an error value; C routines as the return result of the function and
Fortran routines in the last argument.
Before the error value is returned, the current MPI error handler associated with the communication
object (e.g., communicator, window, file) is called. If no communication object is associated with the
MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error
handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after
MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler.
The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using
the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/‐
MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN
error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all
other MPI functions.
Open MPI includes three predefined error handlers that can be used:
• MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.
• MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or session. When
called on a communicator, it acts as if MPI_Abort was called on that communicator. If called on a
window or file, acts as if MPI_Abort was called on a communicator containing the group of processes in
the corresponding window or file. If called on a session, aborts only the local process.
• MPI_ERRORS_RETURN Returns an error code to the application.
MPI applications can also implement their own error handlers by calling:
• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler
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 the Error Handling section of the MPI-3.1 standard for more information.
SEE ALSO:
• MPI_Type_get_contents
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2003-2025, The Open MPI Community
Feb 17, 2025 MPI_TYPE_GET_ENVELOPE(3)