/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
 *  (C) 2001 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */
#include "mpi.h"
#include <stdio.h>
/* stdlib.h Needed for malloc declaration */
#include <stdlib.h>

int main(int argc, char **argv)
{
    int i, n, n_goal = 2048, n_all, rc, n_ranks, *ranks, rank, size, len;
    int group_size;
    MPI_Group *group_array, world_group;
    char msg[MPI_MAX_ERROR_STRING];

    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    n = n_goal;

    group_array = (MPI_Group *) malloc(n * sizeof(MPI_Group));

    MPI_Comm_group(MPI_COMM_WORLD, &world_group);

    n_ranks = size;
    ranks = (int *) malloc(size * sizeof(int));
    for (i = 0; i < size; i++)
        ranks[i] = i;

    MPI_Errhandler_set(MPI_COMM_WORLD, MPI_ERRORS_RETURN);
    for (i = 0; i < n; i++) {
        rc = MPI_Group_incl(world_group, n_ranks, ranks, group_array + i);
        if (rc) {
            fprintf(stderr, "Error when creating group number %d\n", i);
            MPI_Error_string(rc, msg, &len);
            fprintf(stderr, "%s\n", msg);
            n = i + 1;
            break;
        }
        else {
            /* Check that the group was created (and that any errors were
             * caught) */
            rc = MPI_Group_size(group_array[i], &group_size);
            if (group_size != size) {
                fprintf(stderr, "Group number %d not correct (size = %d)\n", i, size);
                n = i + 1;
                break;
            }
        }

    }

    for (i = 0; i < n; i++) {
        rc = MPI_Group_free(group_array + i);
        if (rc) {
            fprintf(stderr, "Error when freeing group number %d\n", i);
            MPI_Error_string(rc, msg, &len);
            fprintf(stderr, "%s\n", msg);
            break;
        }
    }

    MPI_Errhandler_set(MPI_COMM_WORLD, MPI_ERRORS_ARE_FATAL);
    MPI_Group_free(&world_group);

    MPI_Reduce(&n, &n_all, 1, MPI_INT, MPI_MIN, 0, MPI_COMM_WORLD);
    if (rank == 0) {
        /* printf("Completed test of %d type creations\n", n_all); */
        if (n_all != n_goal) {
            printf("This MPI implementation limits the number of groups that can be created\n\
This is allowed by the standard and is not a bug, but is a limit on the\n\
implementation\n");
        }
        else {
            printf(" No Errors\n");
        }
    }

    free(group_array);
    free(ranks);

    MPI_Finalize();
    return 0;
}
