/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */

/*

 *

 *  (C) 2007 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

#include "mpi.h"

#include <stdio.h>

#include <stdlib.h>

#include "mpitest.h"

/*

 * This program tests that MPI_Comm_split applies to intercommunicators;

 * this is an extension added in MPI-2

 */

int main(int argc, char *argv[])

{

    int errs = 0;

    int size, isLeft;

    MPI_Comm intercomm, newcomm;

    MTest_Init(&argc, &argv);

    MPI_Comm_size(MPI_COMM_WORLD, &size);

    if (size < 4) {

        printf("This test requires at least 4 processes\n");

        MPI_Abort(MPI_COMM_WORLD, 1);

    }

    while (MTestGetIntercomm(&intercomm, &isLeft, 2)) {

        int key, color;

        if (intercomm == MPI_COMM_NULL)

            continue;

        /* Split this intercomm.  The new intercomms contain the

         * processes that had odd (resp even) rank in their local group

         * in the original intercomm */

        MTestPrintfMsg(1, "Created intercomm %s\n", MTestGetIntercommName());

        MPI_Comm_rank(intercomm, &key);

        color = (key % 2);

        MPI_Comm_split(intercomm, color, key, &newcomm);

        /* Make sure that the new communicator has the appropriate pieces */

        if (newcomm != MPI_COMM_NULL) {

            int orig_rsize, orig_size, new_rsize, new_size;

            int predicted_size, flag, commok = 1;

            MPI_Comm_test_inter(intercomm, &flag;;

            if (!flag) {

                errs++;

                printf("Output communicator is not an intercomm\n");

                commok = 0;

            }

            MPI_Comm_remote_size(intercomm, &orig_rsize);

            MPI_Comm_remote_size(newcomm, &new_rsize);

            MPI_Comm_size(intercomm, &orig_size);

            MPI_Comm_size(newcomm, &new_size);

            /* The local size is 1/2 the original size, +1 if the

             * size was odd and the color was even.  More precisely,

             * let n be the orig_size.  Then

             * color 0     color 1

             * orig size even    n/2         n/2

             * orig size odd     (n+1)/2     n/2

             *

             * However, since these are integer valued, if n is even,

             * then (n+1)/2 = n/2, so this table is much simpler:

             * color 0     color 1

             * orig size even    (n+1)/2     n/2

             * orig size odd     (n+1)/2     n/2

             *

             */

            predicted_size = (orig_size + !color) / 2;

            if (predicted_size != new_size) {

                errs++;

                printf("Predicted size = %d but found %d for %s (%d,%d)\n",

                       predicted_size, new_size, MTestGetIntercommName(), orig_size, orig_rsize);

                commok = 0;

            }

            predicted_size = (orig_rsize + !color) / 2;

            if (predicted_size != new_rsize) {

                errs++;

                printf("Predicted remote size = %d but found %d for %s (%d,%d)\n",

                       predicted_size, new_rsize, MTestGetIntercommName(), orig_size, orig_rsize);

                commok = 0;

            }

            /* ... more to do */

            if (commok) {

                errs += MTestTestComm(newcomm);

            }

        }

        else {

            int orig_rsize;

            /* If the newcomm is null, then this means that remote group

             * for this color is of size zero (since all processes in this

             * test have been given colors other than MPI_UNDEFINED).

             * Confirm that here */

            /* FIXME: ToDo */

            MPI_Comm_remote_size(intercomm, &orig_rsize);

            if (orig_rsize == 1) {

                if (color == 0) {

                    errs++;

                    printf("Returned null intercomm when non-null expected\n");

                }

            }

        }

        if (newcomm != MPI_COMM_NULL)

            MPI_Comm_free(&newcomm);

        MPI_Comm_free(&intercomm);

    }

    MTest_Finalize(errs);

    MPI_Finalize();

    return 0;

}