NAME¶
MPI_Comm_get_name - Returns the name that was most recently associated
with a communicator.
SYNTAX¶
C Syntax¶
#include <mpi.h>
int MPI_Comm_get_name(MPI_Comm comm, char *comm_name, int *resultlen)
Fortran Syntax¶
INCLUDE 'mpif.h'
MPI_COMM_GET_NAME( COMM, COMM_NAME, RESULTLEN, IERROR)
INTEGER COMM, RESULTLEN, IERROR
CHARACTER*(*) COMM_NAME
C++ Syntax¶
#include <mpi.h>
void MPI::Comm::Get_name(char* comm_name, int& resultlen) const
- comm
- Communicator the name of which is to be returned
(handle).
OUTPUT PARAMETER¶
- comm_name
- Name previously stored on the communicator, or an empty
string if no such name exists (string).
- resultlen
- Length of returned name (integer).
- IERROR
- Fortran only: Error status (integer).
DESCRIPTION¶
MPI_Comm_get_name returns the last name that was previously associated with the
given communicator. The name may be set and retrieved from any language. The
same name will be returned independent of the language used.
comm_name
should be allocated so that it can hold a resulting string of length
MPI_MAX_OBJECT_NAME characters. MPI_Comm_get_name returns a copy of the set
name in
comm_name.
If the user has not associated a name with a communicator, or an error occurs,
MPI_Comm_get_name will return an empty string (all spaces in Fortran,
"" in C and C++). The three predefined communicators will have
predefined names associated with them. Thus, the names of MPI_COMM_WORLD,
MPI_COMM_SELF, and MPI_COMM_PARENT will have the default of MPI_COMM_WORLD,
MPI_COMM_SELF, and MPI_COMM_PARENT. The fact that the system may have chosen
to give a default name to a communicator does not prevent the user from
setting a name on the same communicator; doing this removes the old name and
assigns the new one.
NOTES¶
It is safe simply to print the string returned by MPI_Comm_get_name, as it is
always a valid string even if there was no name.
Note that associating a name with a communicator has no effect on the semantics
of an MPI program, and will (necessarily) increase the store requirement of
the program, since the names must be saved. Therefore, there is no requirement
that users use these functions to associate names with communicators. However
debugging and profiling MPI applications may be made easier if names are
associated with communicators, since the debugger or profiler should then be
able to present information in a less cryptic manner.
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++ functions 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.
