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

/*

 *  (C) 2015 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

/* this deceptively simple test uncovered a bug in the way certain file systems

 * dealt with tuning parmeters.  See

 * https://github.com/open-mpi/ompi/issues/158 and

 * http://trac.mpich.org/projects/mpich/ticket/2261

 *

 * originally uncovered in Darshan:

 * http://lists.mcs.anl.gov/pipermail/darshan-users/2015-February/000256.html

 *

 * to really exercise the bug in simple_collective,

 * we'd have to run on a Lustre or Panasas file system.

 *

 * I am surprised src/mpi/romio/test/create_excl.c did not uncover the bug

 */

#include <assert.h>

#include <stdio.h>

#include <stdlib.h>

#include <fcntl.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <string.h>

#include <sys/time.h>

#include <mpi.h>

#include <errno.h>

#include <getopt.h>

static char *opt_file = NULL;

static int rank = -1;

static int parse_args(int argc, char **argv);

static void usage(const char *prog);

int test_write(char *file, int nprocs, int rank, MPI_Info info)

{

    double stime, etime, wtime, w_elapsed, w_slowest, elapsed, slowest;

    MPI_File fh;

    int ret;

    char buffer[700] = { 0 };

    MPI_Status status;

    int verbose = 0;

    MPI_Barrier(MPI_COMM_WORLD);

    stime = MPI_Wtime();

    ret = MPI_File_open(MPI_COMM_WORLD, file,

                        MPI_MODE_CREATE | MPI_MODE_WRONLY | MPI_MODE_EXCL, info, &fh;;

    if (ret != 0) {

        fprintf(stderr, "Error: failed to open %s\n", file);

        return 1;

    }

    etime = MPI_Wtime();

    ret = MPI_File_write_at_all(fh, rank * 700, buffer, 700, MPI_BYTE, &status);

    if (ret != 0) {

        fprintf(stderr, "Error: failed to write %s\n", file);

        return 1;

    }

    wtime = MPI_Wtime();

    MPI_File_close(&fh;;

    elapsed = etime - stime;

    w_elapsed = wtime - etime;

    MPI_Reduce(&elapsed, &slowest, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);

    MPI_Reduce(&w_elapsed, &w_slowest, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);

    if (rank == 0) {

        unlink(file);

        slowest *= 1000.0;

        w_slowest *= 1000.0;

        if (verbose == 1) {

            printf("file: %s, nprocs: %d, open_time: %f ms, write_time: %f ms\n",

                   file, nprocs, slowest, w_slowest);

        }

    }

    return 0;

}

int main(int argc, char **argv)

{

    int nprocs;

    char file[256];

    MPI_Info info;

    int nr_errors = 0;

    MPI_Init(&argc, &argv);

    MPI_Comm_rank(MPI_COMM_WORLD, &rank;;

    MPI_Comm_size(MPI_COMM_WORLD, &nprocs);

    /* parse the command line arguments */

    parse_args(argc, argv);

    sprintf(file, "%s", opt_file);

    MPI_Info_create(&info;;

    nr_errors += test_write(file, nprocs, rank, info);

    /* acutal value does not matter.  test only writes a small amount of data */

    MPI_Info_set(info, "striping_factor", "50");

    nr_errors += test_write(file, nprocs, rank, info);

    MPI_Info_free(&info;;

    MPI_Finalize();

    if (!rank && nr_errors == 0) {

        printf(" No Errors\n");

    }

    return (-nr_errors);

}

static int parse_args(int argc, char **argv)

{

    int c;

    while ((c = getopt(argc, argv, "e")) != EOF) {

        switch (c) {

        case 'h':

            if (rank == 0)

                usage(argv[0]);

            exit(0);

        case '?':      /* unknown */

            if (rank == 0)

                usage(argv[0]);

            exit(1);

        default:

            break;

        }

    }

    if (argc - optind != 1) {

        if (rank == 0)

            usage(argv[0]);

        exit(1);

    }

    opt_file = strdup(argv[optind]);

    assert(opt_file);

    return (0);

}

static void usage(const char *prog)

{

    printf("Usage: %s [<OPTIONS>...] <FILE NAME>\n", prog);

    printf("\n<OPTIONS> is one or more of\n");

    printf(" -h       print this help\n");

}

/*

 * vim: ts=8 sts=4 sw=4 noexpandtab

 */