/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
 * vim:expandtab:shiftwidth=8:tabstop=8:
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdarg.h>

#include "mpi.h"

void usage(char *prog)
{
        printf("usage: %s {-o|-m|-l<tgt>} filenamefmt count\n", prog);
        printf("       %s {-o|-m|-l<tgt>} filenamefmt -seconds\n", prog);
        printf("       %s {-o|-m|-l<tgt>} filenamefmt start count\n", prog);
}

/* Print process rank, loop count, message, and exit (i.e. a fatal error) */
int rprintf(int rank, int loop, const char *fmt, ...)
{
        va_list       ap;

        printf("rank %d, loop %d: ", rank, loop);

        va_start(ap, fmt);

        printf(fmt, ap);

        MPI_Finalize();
        exit(1);
}

int main(int argc, char ** argv)
{
        int i, rc = 0, do_open = 0, do_link = 0, rank;
        char format[4096], *fmt, *tgt;
        char filename[4096];
        long start, last, end;
        long begin = 0, count;

        rc = MPI_Init(&argc, &argv);
        if (rc != MPI_SUCCESS)
                rprintf(-1, -1, "MPI_Init failed: %d\n", rc);

        if (argc < 4 || argc > 5) {
                usage(argv[0]);
                return 1;
        }

        if (strcmp(argv[1], "-o") == 0) {
                tgt = NULL;
                do_open = 1;
        } else if (strncmp(argv[1], "-l", 2) == 0 && argv[1][2]) {
                tgt = argv[1] + 2;
                do_link = 1;
        } else if (strcmp(argv[1], "-m") != 0) {
                usage(argv[0]);
                return 1;
        }

        if (strlen(argv[2]) > 4080) {
                printf("name too long\n");
                return 1;
        }

        rc = MPI_Comm_rank(MPI_COMM_WORLD, &rank);
        if (rc != MPI_SUCCESS)
                rprintf(-1, -1, "MPI_Comm_rank failed: %d\n", rc);

        rc = MPI_Barrier(MPI_COMM_WORLD);
        if (rc != MPI_SUCCESS)
                rprintf(rank, -1, "prep MPI_Barrier failed: %d\n", rc);

        start = last = time(0);

        if (argc == 4) {
                end = strtol(argv[3], NULL, 0);
        } else {
                begin = strtol(argv[3], NULL, 0);
                end = strtol(argv[4], NULL, 0);
        }
        if (end > 0) {
                count = end;
                end = -1UL >> 1;
        } else {
                end = start - end;
                count = -1UL >> 1;
        }

        if (strchr(argv[2], '%'))
                fmt = argv[2];
        else {
                sprintf(format, "%s%%d", argv[2]);
                fmt = format;
        }
        printf("starting at %s", ctime(&start));
        for (i = 0; i < count && time(0) < end; i++, begin++) {
                sprintf(filename, fmt, begin);
                if (do_open) {
                        int fd = open(filename, O_CREAT|O_RDWR, 0644);
                        if (fd < 0) {
                                printf("open(%s) error: %s\n", filename,
                                       strerror(errno));
                                rc = errno;
                                break;
                        }
                        close(fd);
                } else if (do_link) {
                        rc = link(tgt, filename);
                        if (rc) {
                                printf("link(%s, %s) error: %s\n",
                                       tgt, filename, strerror(errno));
                                rc = errno;
                                break;
                        }
                } else {
                        rc = mknod(filename, S_IFREG| 0444, 0);
                        if (rc) {
                                printf("mknod(%s) error: %s\n",
                                       filename, strerror(errno));
                                rc = errno;
                                break;
                        }
                }
                if ((i % 10000) == 0) {
                        printf(" - created %d (time %ld total %ld last %ld)\n",
                               i, time(0), time(0) - start, time(0) - last);
                        last = time(0);
                }
        }
        printf("total: %d creates in %ld seconds: %f creates/second\n", i,
               time(0) - start, ((float)i / (time(0) - start)));
        start = time(0);
        printf("finish at %s", ctime(&start));

        return rc;
}