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MPI_Comm_get_name - Returns the name that was most recently associated
with a communicator.
#include <mpi.h>
int MPI_Comm_get_name(MPI_Comm comm, char *comm_name, int *resultlen)
INCLUDE ’mpif.h’
MPI_COMM_GET_NAME(COMM, COMM_NAME, RESULTLEN, IERROR)
INTEGER COMM, RESULTLEN, IERROR
CHARACTER*(*) COMM_NAME
#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).
- 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).
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.
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.
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.
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