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

/*

 *  (C) 2011 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

/* This test ensures that MPI_Comm_split breaks ties in key values by using the

 * original rank in the input communicator.  This typically corresponds to

 * the difference between using a stable sort or using an unstable sort.

 *

 * It checks all sizes from 1..comm_size(world)-1, so this test does not need to

 * be run multiple times at process counts from a higher-level test driver. */

#include <stdio.h>

#include <stdlib.h>

#include "mpi.h"

#include "mpitest.h"

#define ERRLIMIT (10)

#define my_assert(cond_)                                     \

    do {                                                     \

        if (!(cond_)) {                                      \

            if (errs < ERRLIMIT)                             \

                printf("assertion \"%s\" failed\n", #cond_); \

            ++errs;                                          \

        }                                                    \

    } while (0)

int main(int argc, char **argv)

{

    int i, j, pos, modulus, cs, rank, size;

    int wrank, wsize;

    int newrank, newsize;

    int errs = 0;

    int key;

    int *oldranks = NULL;

    int *identity = NULL;

    int verbose = 0;

    MPI_Comm comm, splitcomm;

    MPI_Group wgroup, newgroup;

    MTest_Init(&argc, &argv);

    if (getenv("MPITEST_VERBOSE"))

        verbose = 1;

    MPI_Comm_rank(MPI_COMM_WORLD, &wrank);

    MPI_Comm_size(MPI_COMM_WORLD, &wsize);

    oldranks = malloc(wsize * sizeof(int));

    identity = malloc(wsize * sizeof(int));

    for (i = 0; i < wsize; ++i) {

        identity[i] = i;

    }

    for (cs = 1; cs <= wsize; ++cs) {

        /* yes, we are using comm_split to test comm_split, but this test is

         * mainly about ensuring that the stable sort behavior is correct, not

         * about whether the partitioning by color behavior is correct */

        MPI_Comm_split(MPI_COMM_WORLD, (wrank < cs ? 0 : MPI_UNDEFINED), wrank, &comm);

        if (comm != MPI_COMM_NULL) {

            MPI_Comm_rank(comm, &rank;;

            MPI_Comm_size(comm, &size);

            for (modulus = 1; modulus <= size; ++modulus) {

                /* Divide all ranks into one of "modulus" equivalence classes.  Ranks in

                 * output comm will be ordered first by class, then within the class by

                 * rank in comm world. */

                key = rank % modulus;

                /* all pass same color, variable keys */

                MPI_Comm_split(comm, 5, key, &splitcomm);

                MPI_Comm_rank(splitcomm, &newrank);

                MPI_Comm_size(splitcomm, &newsize);

                my_assert(newsize == size);

                MPI_Comm_group(MPI_COMM_WORLD, &wgroup);

                MPI_Comm_group(splitcomm, &newgroup);

                int gsize;

                MPI_Group_size(newgroup, &gsize);

                MPI_Group_translate_ranks(newgroup, size, identity, wgroup, oldranks);

                MPI_Group_free(&wgroup);

                MPI_Group_free(&newgroup);

                if (splitcomm != MPI_COMM_NULL)

                    MPI_Comm_free(&splitcomm);

                /* now check that comm_split broke any ties correctly */

                if (rank == 0) {

                    if (verbose) {

                        /* debugging code that is useful when the test fails */

                        printf("modulus=%d oldranks={", modulus);

                        for (i = 0; i < size - 1; ++i) {

                            printf("%d,", oldranks[i]);

                        }

                        printf("%d} keys={", oldranks[i]);

                        for (i = 0; i < size - 1; ++i) {

                            printf("%d,", i % modulus);

                        }

                        printf("%d}\n", i % modulus);

                    }

                    pos = 0;

                    for (i = 0; i < modulus; ++i) {

                        /* there's probably a better way to write these loop bounds and

                         * indices, but this is the first (correct) way that occurred to me */

                        for (j = 0; j < (size / modulus + (i < size % modulus ? 1 : 0)); ++j) {

                            if (errs < ERRLIMIT && oldranks[pos] != i + modulus * j) {

                                printf

                                    ("size=%d i=%d j=%d modulus=%d pos=%d i+modulus*j=%d oldranks[pos]=%d\n",

                                     size, i, j, modulus, pos, i + modulus * j, oldranks[pos]);

                            }

                            my_assert(oldranks[pos] == i + modulus * j);

                            ++pos;

                        }

                    }

                }

            }

            MPI_Comm_free(&comm);

        }

    }

    if (oldranks != NULL)

        free(oldranks);

    if (identity != NULL)

        free(identity);

    MTest_Finalize(errs);

    return MTestReturnValue(errs);

}