oracular (3) MPI_Comm_get_attr.openmpi.3.gz

NAME

       MPI_Comm_get_attr - Retrieves attribute value by key.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval,
            void *attribute_val, int *flag)

Fortran Syntax (see FORTRAN 77 NOTES)

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_COMM_GET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, FLAG, IERROR)
            INTEGER   COMM, COMM_KEYVAL, IERROR
            INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL
            LOGICAL FLAG

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Comm_get_attr(comm, comm_keyval, attribute_val, flag, ierror)
            TYPE(MPI_Comm), INTENT(IN) :: comm
            INTEGER, INTENT(IN) :: comm_keyval
            INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(OUT) :: attribute_val
            LOGICAL, INTENT(OUT) :: flag
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       bool MPI::Comm::Get_attr(int comm_keyval, void* attribute_val)
            const

INPUT PARAMETERS

       comm      Communicator to which the attribute is attached (handle).

       comm_keyval
                 Key value (integer).

OUTPUT PARAMETER

       attribute_val
                 Attribute value, unless flag = false.

       flag      False if no attribute is associated with the key (logical).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Comm_get_attr  retrieves  an  attribute  value  by key. The call is erroneous if there is no key with
       value keyval. On the other hand, the call is correct if  the  key  value  exists,  but  no  attribute  is
       attached  on  comm  for  that  key;  in  that  case,  the  call  returns  flag  =  false.  In particular,
       MPI_KEYVAL_INVALID is an erroneous key value.

       This function replaces MPI_Attr_get, the use of which is deprecated. The  C  binding  is  identical.  The
       Fortran binding differs in that attribute_val is an address-sized integer.

FORTRAN 77 NOTES

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

            INTEGER*MPI_ADDRESS_KIND ATTRIBUTE_VAL

       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++ 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.