path: root/examples/ph5example.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://www.hdfgroup.org/licenses.               *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Example of using the parallel HDF5 library to access datasets.
 * Last revised: April 24, 2001.
 *
 * This program contains two parts.  In the first part, the mpi processes
 * collectively create a new parallel HDF5 file and create two fixed
 * dimension datasets in it.  Then each process writes a hyperslab into
 * each dataset in an independent mode.  All processes collectively
 * close the datasets and the file.
 * In the second part, the processes collectively open the created file
 * and the two datasets in it.  Then each process reads a hyperslab from
 * each dataset in an independent mode and prints them out.
 * All processes collectively close the datasets and the file.
 *
 * The need of requirement of parallel file prefix is that in general
 * the current working directory in which compiling is done, is not suitable
 * for parallel I/O and there is no standard pathname for parallel file
 * systems.  In some cases, the parallel file name may even needs some
 * parallel file type prefix such as: "pfs:/GF/...".  Therefore, this
 * example requires an explicit parallel file prefix.  See the usage
 * for more detail.
 */

#include <assert.h>
#include "hdf5.h"
#include <string.h>
#include <stdlib.h>

#ifdef H5_HAVE_PARALLEL
/* Temporary source code */
#define FAIL -1
/* temporary code end */

/* Define some handy debugging shorthands, routines, ... */
/* debugging tools */
#define MESG(x)                                                                                              \
    if (verbose)                                                                                             \
        printf("%s\n", x);

#define MPI_BANNER(mesg)                                                                                     \
    {                                                                                                        \
        printf("--------------------------------\n");                                                        \
        printf("Proc %d: ", mpi_rank);                                                                       \
        printf("*** %s\n", mesg);                                                                            \
        printf("--------------------------------\n");                                                        \
    }

#define SYNC(comm)                                                                                           \
    {                                                                                                        \
        MPI_BANNER("doing a SYNC");                                                                          \
        MPI_Barrier(comm);                                                                                   \
        MPI_BANNER("SYNC DONE");                                                                             \
    }
/* End of Define some handy debugging shorthands, routines, ... */

/* Constants definitions */
/* 24 is a multiple of 2, 3, 4, 6, 8, 12.  Neat for parallel tests. */
#define SPACE1_DIM1  24
#define SPACE1_DIM2  24
#define SPACE1_RANK  2
#define DATASETNAME1 "Data1"
#define DATASETNAME2 "Data2"
#define DATASETNAME3 "Data3"
/* hyperslab layout styles */
#define BYROW 1 /* divide into slabs of rows */
#define BYCOL 2 /* divide into blocks of columns */

#define PARAPREFIX "HDF5_PARAPREFIX" /* file prefix environment variable name */

/* dataset data type.  Int's can be easily octo dumped. */
typedef int DATATYPE;

/* global variables */
int nerrors = 0; /* errors count */
#ifndef PATH_MAX
#define PATH_MAX 512
#endif /* !PATH_MAX */
char testfiles[2][PATH_MAX];

int mpi_size, mpi_rank; /* mpi variables */

/* option flags */
int verbose   = 0; /* verbose, default as no. */
int doread    = 1; /* read test */
int dowrite   = 1; /* write test */
int docleanup = 1; /* cleanup */

/* Prototypes */
void slab_set(hsize_t start[], hsize_t count[], hsize_t stride[], int mode);
void dataset_fill(hsize_t start[], hsize_t count[], hsize_t stride[], DATATYPE *dataset);
void dataset_print(hsize_t start[], hsize_t count[], hsize_t stride[], DATATYPE *dataset);
int  dataset_vrfy(hsize_t start[], hsize_t count[], hsize_t stride[], DATATYPE *dataset, DATATYPE *original);
void phdf5writeInd(char *filename);
void phdf5readInd(char *filename);
void phdf5writeAll(char *filename);
void phdf5readAll(char *filename);
void test_split_comm_access(char filenames[][PATH_MAX]);
int  parse_options(int argc, char **argv);
void usage(void);
int  mkfilenames(char *prefix);
void cleanup(void);

/*
 * Setup the dimensions of the hyperslab.
 * Two modes--by rows or by columns.
 * Assume dimension rank is 2.
 */
void
slab_set(hsize_t start[], hsize_t count[], hsize_t stride[], int mode)
{
    switch (mode) {
        case BYROW:
            /* Each process takes a slabs of rows. */
            stride[0] = 1;
            stride[1] = 1;
            count[0]  = SPACE1_DIM1 / mpi_size;
            count[1]  = SPACE1_DIM2;
            start[0]  = mpi_rank * count[0];
            start[1]  = 0;
            break;
        case BYCOL:
            /* Each process takes a block of columns. */
            stride[0] = 1;
            stride[1] = 1;
            count[0]  = SPACE1_DIM1;
            count[1]  = SPACE1_DIM2 / mpi_size;
            start[0]  = 0;
            start[1]  = mpi_rank * count[1];
            break;
        default:
            /* Unknown mode.  Set it to cover the whole dataset. */
            printf("unknown slab_set mode (%d)\n", mode);
            stride[0] = 1;
            stride[1] = 1;
            count[0]  = SPACE1_DIM1;
            count[1]  = SPACE1_DIM2;
            start[0]  = 0;
            start[1]  = 0;
            break;
    }
}

/*
 * Fill the dataset with trivial data for testing.
 * Assume dimension rank is 2 and data is stored contiguous.
 */
void
dataset_fill(hsize_t start[], hsize_t count[], hsize_t stride[], DATATYPE *dataset)
{
    DATATYPE *dataptr = dataset;
    hsize_t   i, j;

    /* put some trivial data in the data_array */
    for (i = 0; i < count[0]; i++) {
        for (j = 0; j < count[1]; j++) {
            *dataptr++ = (i * stride[0] + start[0]) * 100 + (j * stride[1] + start[1] + 1);
        }
    }
}

/*
 * Print the content of the dataset.
 */
void
dataset_print(hsize_t start[], hsize_t count[], hsize_t stride[], DATATYPE *dataset)
{
    DATATYPE *dataptr = dataset;
    hsize_t   i, j;

    /* print the slab read */
    for (i = 0; i < count[0]; i++) {
        printf("Row %lu: ", (unsigned long)(i * stride[0] + start[0]));
        for (j = 0; j < count[1]; j++) {
            printf("%03d ", *dataptr++);
        }
        printf("\n");
    }
}

/*
 * Print the content of the dataset.
 */
int
dataset_vrfy(hsize_t start[], hsize_t count[], hsize_t stride[], DATATYPE *dataset, DATATYPE *original)
{
#define MAX_ERR_REPORT 10 /* Maximum number of errors reported */

    hsize_t i, j;
    int     nerr;

    /* print it if verbose */
    if (verbose)
        dataset_print(start, count, stride, dataset);

    nerr = 0;
    for (i = 0; i < count[0]; i++) {
        for (j = 0; j < count[1]; j++) {
            if (*dataset++ != *original++) {
                nerr++;
                if (nerr <= MAX_ERR_REPORT) {
                    printf("Dataset Verify failed at [%lu][%lu](row %lu, col %lu): expect %d, got %d\n",
                           (unsigned long)i, (unsigned long)j, (unsigned long)(i * stride[0] + start[0]),
                           (unsigned long)(j * stride[1] + start[1]), *(dataset - 1), *(original - 1));
                }
            }
        }
    }
    if (nerr > MAX_ERR_REPORT)
        printf("[more errors ...]\n");
    if (nerr)
        printf("%d errors found in dataset_vrfy\n", nerr);
    return (nerr);
}

/*
 * Example of using the parallel HDF5 library to create two datasets
 * in one HDF5 files with parallel MPIO access support.
 * The Datasets are of sizes (number-of-mpi-processes x DIM1) x DIM2.
 * Each process controls only a slab of size DIM1 x DIM2 within each
 * dataset.
 */

void
phdf5writeInd(char *filename)
{
    hid_t    fid1;                                            /* HDF5 file IDs */
    hid_t    acc_tpl1;                                        /* File access templates */
    hid_t    sid1;                                            /* Dataspace ID */
    hid_t    file_dataspace;                                  /* File dataspace ID */
    hid_t    mem_dataspace;                                   /* memory dataspace ID */
    hid_t    dataset1, dataset2;                              /* Dataset ID */
    hsize_t  dims1[SPACE1_RANK] = {SPACE1_DIM1, SPACE1_DIM2}; /* dataspace dim sizes */
    DATATYPE data_array1[SPACE1_DIM1][SPACE1_DIM2];           /* data buffer */

    hsize_t start[SPACE1_RANK];                      /* for hyperslab setting */
    hsize_t count[SPACE1_RANK], stride[SPACE1_RANK]; /* for hyperslab setting */

    herr_t ret; /* Generic return value */

    MPI_Comm comm = MPI_COMM_WORLD;
    MPI_Info info = MPI_INFO_NULL;

    if (verbose)
        printf("Independent write test on file %s\n", filename);

    /* -------------------
     * START AN HDF5 FILE
     * -------------------*/
    /* setup file access template with parallel IO access. */
    acc_tpl1 = H5Pcreate(H5P_FILE_ACCESS);
    assert(acc_tpl1 != FAIL);
    MESG("H5Pcreate access succeed");
    /* set Parallel access with communicator */
    ret = H5Pset_fapl_mpio(acc_tpl1, comm, info);
    assert(ret != FAIL);
    MESG("H5Pset_fapl_mpio succeed");

    /* create the file collectively */
    fid1 = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, acc_tpl1);
    assert(fid1 != FAIL);
    MESG("H5Fcreate succeed");

    /* Release file-access template */
    ret = H5Pclose(acc_tpl1);
    assert(ret != FAIL);

    /* --------------------------
     * Define the dimensions of the overall datasets
     * and the slabs local to the MPI process.
     * ------------------------- */
    /* setup dimensionality object */
    sid1 = H5Screate_simple(SPACE1_RANK, dims1, NULL);
    assert(sid1 != FAIL);
    MESG("H5Screate_simple succeed");

    /* create a dataset collectively */
    dataset1 = H5Dcreate2(fid1, DATASETNAME1, H5T_NATIVE_INT, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
    assert(dataset1 != FAIL);
    MESG("H5Dcreate2 succeed");

    /* create another dataset collectively */
    dataset2 = H5Dcreate2(fid1, DATASETNAME2, H5T_NATIVE_INT, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
    assert(dataset2 != FAIL);
    MESG("H5Dcreate2 succeed");

    /* set up dimensions of the slab this process accesses */
    start[0]  = mpi_rank * SPACE1_DIM1 / mpi_size;
    start[1]  = 0;
    count[0]  = SPACE1_DIM1 / mpi_size;
    count[1]  = SPACE1_DIM2;
    stride[0] = 1;
    stride[1] = 1;
    if (verbose)
        printf("start[]=(%lu,%lu), count[]=(%lu,%lu), total datapoints=%lu\n", (unsigned long)start[0],
               (unsigned long)start[1], (unsigned long)count[0], (unsigned long)count[1],
               (unsigned long)(count[0] * count[1]));

    /* put some trivial data in the data_array */
    dataset_fill(start, count, stride, &data_array1[0][0]);
    MESG("data_array initialized");

    /* create a file dataspace independently */
    file_dataspace = H5Dget_space(dataset1);
    assert(file_dataspace != FAIL);
    MESG("H5Dget_space succeed");
    ret = H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL);
    assert(ret != FAIL);
    MESG("H5Sset_hyperslab succeed");

    /* create a memory dataspace independently */
    mem_dataspace = H5Screate_simple(SPACE1_RANK, count, NULL);
    assert(mem_dataspace != FAIL);

    /* write data independently */
    ret = H5Dwrite(dataset1, H5T_NATIVE_INT, mem_dataspace, file_dataspace, H5P_DEFAULT, data_array1);
    assert(ret != FAIL);
    MESG("H5Dwrite succeed");

    /* write data independently */
    ret = H5Dwrite(dataset2, H5T_NATIVE_INT, mem_dataspace, file_dataspace, H5P_DEFAULT, data_array1);
    assert(ret != FAIL);
    MESG("H5Dwrite succeed");

    /* release dataspace ID */
    H5Sclose(file_dataspace);

    /* close dataset collectively */
    ret = H5Dclose(dataset1);
    assert(ret != FAIL);
    MESG("H5Dclose1 succeed");
    ret = H5Dclose(dataset2);
    assert(ret != FAIL);
    MESG("H5Dclose2 succeed");

    /* release all IDs created */
    H5Sclose(sid1);

    /* close the file collectively */
    H5Fclose(fid1);
}

/* Example of using the parallel HDF5 library to read a dataset */
void
phdf5readInd(char *filename)
{
    hid_t    fid1;                                   /* HDF5 file IDs */
    hid_t    acc_tpl1;                               /* File access templates */
    hid_t    file_dataspace;                         /* File dataspace ID */
    hid_t    mem_dataspace;                          /* memory dataspace ID */
    hid_t    dataset1, dataset2;                     /* Dataset ID */
    DATATYPE data_array1[SPACE1_DIM1][SPACE1_DIM2];  /* data buffer */
    DATATYPE data_origin1[SPACE1_DIM1][SPACE1_DIM2]; /* expected data buffer */

    hsize_t start[SPACE1_RANK];                      /* for hyperslab setting */
    hsize_t count[SPACE1_RANK], stride[SPACE1_RANK]; /* for hyperslab setting */

    herr_t ret; /* Generic return value */

    MPI_Comm comm = MPI_COMM_WORLD;
    MPI_Info info = MPI_INFO_NULL;

    if (verbose)
        printf("Independent read test on file %s\n", filename);

    /* setup file access template */
    acc_tpl1 = H5Pcreate(H5P_FILE_ACCESS);
    assert(acc_tpl1 != FAIL);
    /* set Parallel access with communicator */
    ret = H5Pset_fapl_mpio(acc_tpl1, comm, info);
    assert(ret != FAIL);

    /* open the file collectively */
    fid1 = H5Fopen(filename, H5F_ACC_RDWR, acc_tpl1);
    assert(fid1 != FAIL);

    /* Release file-access template */
    ret = H5Pclose(acc_tpl1);
    assert(ret != FAIL);

    /* open the dataset1 collectively */
    dataset1 = H5Dopen2(fid1, DATASETNAME1, H5P_DEFAULT);
    assert(dataset1 != FAIL);

    /* open another dataset collectively */
    dataset2 = H5Dopen2(fid1, DATASETNAME1, H5P_DEFAULT);
    assert(dataset2 != FAIL);

    /* set up dimensions of the slab this process accesses */
    start[0]  = mpi_rank * SPACE1_DIM1 / mpi_size;
    start[1]  = 0;
    count[0]  = SPACE1_DIM1 / mpi_size;
    count[1]  = SPACE1_DIM2;
    stride[0] = 1;
    stride[1] = 1;
    if (verbose)
        printf("start[]=(%lu,%lu), count[]=(%lu,%lu), total datapoints=%lu\n", (unsigned long)start[0],
               (unsigned long)start[1], (unsigned long)count[0], (unsigned long)count[1],
               (unsigned long)(count[0] * count[1]));

    /* create a file dataspace independently */
    file_dataspace = H5Dget_space(dataset1);
    assert(file_dataspace != FAIL);
    ret = H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL);
    assert(ret != FAIL);

    /* create a memory dataspace independently */
    mem_dataspace = H5Screate_simple(SPACE1_RANK, count, NULL);
    assert(mem_dataspace != FAIL);

    /* fill dataset with test data */
    dataset_fill(start, count, stride, &data_origin1[0][0]);

    /* read data independently */
    ret = H5Dread(dataset1, H5T_NATIVE_INT, mem_dataspace, file_dataspace, H5P_DEFAULT, data_array1);
    assert(ret != FAIL);

    /* verify the read data with original expected data */
    ret = dataset_vrfy(start, count, stride, &data_array1[0][0], &data_origin1[0][0]);
    assert(ret != FAIL);

    /* read data independently */
    ret = H5Dread(dataset2, H5T_NATIVE_INT, mem_dataspace, file_dataspace, H5P_DEFAULT, data_array1);
    assert(ret != FAIL);

    /* verify the read data with original expected data */
    ret = dataset_vrfy(start, count, stride, &data_array1[0][0], &data_origin1[0][0]);
    assert(ret == 0);

    /* close dataset collectively */
    ret = H5Dclose(dataset1);
    assert(ret != FAIL);
    ret = H5Dclose(dataset2);
    assert(ret != FAIL);

    /* release all IDs created */
    H5Sclose(file_dataspace);

    /* close the file collectively */
    H5Fclose(fid1);
}

/*
 * Example of using the parallel HDF5 library to create two datasets
 * in one HDF5 file with collective parallel access support.
 * The Datasets are of sizes (number-of-mpi-processes x DIM1) x DIM2.
 * Each process controls only a slab of size DIM1 x DIM2 within each
 * dataset. [Note: not so yet.  Datasets are of sizes DIM1xDIM2 and
 * each process controls a hyperslab within.]
 */

void
phdf5writeAll(char *filename)
{
    hid_t    fid1;                                            /* HDF5 file IDs */
    hid_t    acc_tpl1;                                        /* File access templates */
    hid_t    xfer_plist;                                      /* Dataset transfer properties list */
    hid_t    sid1;                                            /* Dataspace ID */
    hid_t    file_dataspace;                                  /* File dataspace ID */
    hid_t    mem_dataspace;                                   /* memory dataspace ID */
    hid_t    dataset1, dataset2;                              /* Dataset ID */
    hsize_t  dims1[SPACE1_RANK] = {SPACE1_DIM1, SPACE1_DIM2}; /* dataspace dim sizes */
    DATATYPE data_array1[SPACE1_DIM1][SPACE1_DIM2];           /* data buffer */

    hsize_t start[SPACE1_RANK];                      /* for hyperslab setting */
    hsize_t count[SPACE1_RANK], stride[SPACE1_RANK]; /* for hyperslab setting */

    herr_t ret; /* Generic return value */

    MPI_Comm comm = MPI_COMM_WORLD;
    MPI_Info info = MPI_INFO_NULL;

    if (verbose)
        printf("Collective write test on file %s\n", filename);

    /* -------------------
     * START AN HDF5 FILE
     * -------------------*/
    /* setup file access template with parallel IO access. */
    acc_tpl1 = H5Pcreate(H5P_FILE_ACCESS);
    assert(acc_tpl1 != FAIL);
    MESG("H5Pcreate access succeed");
    /* set Parallel access with communicator */
    ret = H5Pset_fapl_mpio(acc_tpl1, comm, info);
    assert(ret != FAIL);
    MESG("H5Pset_fapl_mpio succeed");

    /* create the file collectively */
    fid1 = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, acc_tpl1);
    assert(fid1 != FAIL);
    MESG("H5Fcreate succeed");

    /* Release file-access template */
    ret = H5Pclose(acc_tpl1);
    assert(ret != FAIL);

    /* --------------------------
     * Define the dimensions of the overall datasets
     * and create the dataset
     * ------------------------- */
    /* setup dimensionality object */
    sid1 = H5Screate_simple(SPACE1_RANK, dims1, NULL);
    assert(sid1 != FAIL);
    MESG("H5Screate_simple succeed");

    /* create a dataset collectively */
    dataset1 = H5Dcreate2(fid1, DATASETNAME1, H5T_NATIVE_INT, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
    assert(dataset1 != FAIL);
    MESG("H5Dcreate2 succeed");

    /* create another dataset collectively */
    dataset2 = H5Dcreate2(fid1, DATASETNAME2, H5T_NATIVE_INT, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
    assert(dataset2 != FAIL);
    MESG("H5Dcreate2 2 succeed");

    /*
     * Set up dimensions of the slab this process accesses.
     */

    /* Dataset1: each process takes a block of rows. */
    slab_set(start, count, stride, BYROW);
    if (verbose)
        printf("start[]=(%lu,%lu), count[]=(%lu,%lu), total datapoints=%lu\n", (unsigned long)start[0],
               (unsigned long)start[1], (unsigned long)count[0], (unsigned long)count[1],
               (unsigned long)(count[0] * count[1]));

    /* create a file dataspace independently */
    file_dataspace = H5Dget_space(dataset1);
    assert(file_dataspace != FAIL);
    MESG("H5Dget_space succeed");
    ret = H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL);
    assert(ret != FAIL);
    MESG("H5Sset_hyperslab succeed");

    /* create a memory dataspace independently */
    mem_dataspace = H5Screate_simple(SPACE1_RANK, count, NULL);
    assert(mem_dataspace != FAIL);

    /* fill the local slab with some trivial data */
    dataset_fill(start, count, stride, &data_array1[0][0]);
    MESG("data_array initialized");
    if (verbose) {
        MESG("data_array created");
        dataset_print(start, count, stride, &data_array1[0][0]);
    }

    /* set up the collective transfer properties list */
    xfer_plist = H5Pcreate(H5P_DATASET_XFER);
    assert(xfer_plist != FAIL);
    ret = H5Pset_dxpl_mpio(xfer_plist, H5FD_MPIO_COLLECTIVE);
    assert(ret != FAIL);
    MESG("H5Pcreate xfer succeed");

    /* write data collectively */
    ret = H5Dwrite(dataset1, H5T_NATIVE_INT, mem_dataspace, file_dataspace, xfer_plist, data_array1);
    assert(ret != FAIL);
    MESG("H5Dwrite succeed");

    /* release all temporary handles. */
    /* Could have used them for dataset2 but it is cleaner */
    /* to create them again.*/
    H5Sclose(file_dataspace);
    H5Sclose(mem_dataspace);
    H5Pclose(xfer_plist);

    /* Dataset2: each process takes a block of columns. */
    slab_set(start, count, stride, BYCOL);
    if (verbose)
        printf("start[]=(%lu,%lu), count[]=(%lu,%lu), total datapoints=%lu\n", (unsigned long)start[0],
               (unsigned long)start[1], (unsigned long)count[0], (unsigned long)count[1],
               (unsigned long)(count[0] * count[1]));

    /* put some trivial data in the data_array */
    dataset_fill(start, count, stride, &data_array1[0][0]);
    MESG("data_array initialized");
    if (verbose) {
        MESG("data_array created");
        dataset_print(start, count, stride, &data_array1[0][0]);
    }

    /* create a file dataspace independently */
    file_dataspace = H5Dget_space(dataset1);
    assert(file_dataspace != FAIL);
    MESG("H5Dget_space succeed");
    ret = H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL);
    assert(ret != FAIL);
    MESG("H5Sset_hyperslab succeed");

    /* create a memory dataspace independently */
    mem_dataspace = H5Screate_simple(SPACE1_RANK, count, NULL);
    assert(mem_dataspace != FAIL);

    /* fill the local slab with some trivial data */
    dataset_fill(start, count, stride, &data_array1[0][0]);
    MESG("data_array initialized");
    if (verbose) {
        MESG("data_array created");
        dataset_print(start, count, stride, &data_array1[0][0]);
    }

    /* set up the collective transfer properties list */
    xfer_plist = H5Pcreate(H5P_DATASET_XFER);
    assert(xfer_plist != FAIL);
    ret = H5Pset_dxpl_mpio(xfer_plist, H5FD_MPIO_COLLECTIVE);
    assert(ret != FAIL);
    MESG("H5Pcreate xfer succeed");

    /* write data independently */
    ret = H5Dwrite(dataset2, H5T_NATIVE_INT, mem_dataspace, file_dataspace, xfer_plist, data_array1);
    assert(ret != FAIL);
    MESG("H5Dwrite succeed");

    /* release all temporary handles. */
    H5Sclose(file_dataspace);
    H5Sclose(mem_dataspace);
    H5Pclose(xfer_plist);

    /*
     * All writes completed.  Close datasets collectively
     */
    ret = H5Dclose(dataset1);
    assert(ret != FAIL);
    MESG("H5Dclose1 succeed");
    ret = H5Dclose(dataset2);
    assert(ret != FAIL);
    MESG("H5Dclose2 succeed");

    /* release all IDs created */
    H5Sclose(sid1);

    /* close the file collectively */
    H5Fclose(fid1);
}

/*
 * Example of using the parallel HDF5 library to read two datasets
 * in one HDF5 file with collective parallel access support.
 * The Datasets are of sizes (number-of-mpi-processes x DIM1) x DIM2.
 * Each process controls only a slab of size DIM1 x DIM2 within each
 * dataset. [Note: not so yet.  Datasets are of sizes DIM1xDIM2 and
 * each process controls a hyperslab within.]
 */

void
phdf5readAll(char *filename)
{
    hid_t    fid1;                                   /* HDF5 file IDs */
    hid_t    acc_tpl1;                               /* File access templates */
    hid_t    xfer_plist;                             /* Dataset transfer properties list */
    hid_t    file_dataspace;                         /* File dataspace ID */
    hid_t    mem_dataspace;                          /* memory dataspace ID */
    hid_t    dataset1, dataset2;                     /* Dataset ID */
    DATATYPE data_array1[SPACE1_DIM1][SPACE1_DIM2];  /* data buffer */
    DATATYPE data_origin1[SPACE1_DIM1][SPACE1_DIM2]; /* expected data buffer */

    hsize_t start[SPACE1_RANK];                      /* for hyperslab setting */
    hsize_t count[SPACE1_RANK], stride[SPACE1_RANK]; /* for hyperslab setting */

    herr_t ret; /* Generic return value */

    MPI_Comm comm = MPI_COMM_WORLD;
    MPI_Info info = MPI_INFO_NULL;

    if (verbose)
        printf("Collective read test on file %s\n", filename);

    /* -------------------
     * OPEN AN HDF5 FILE
     * -------------------*/
    /* setup file access template with parallel IO access. */
    acc_tpl1 = H5Pcreate(H5P_FILE_ACCESS);
    assert(acc_tpl1 != FAIL);
    MESG("H5Pcreate access succeed");
    /* set Parallel access with communicator */
    ret = H5Pset_fapl_mpio(acc_tpl1, comm, info);
    assert(ret != FAIL);
    MESG("H5Pset_fapl_mpio succeed");

    /* open the file collectively */
    fid1 = H5Fopen(filename, H5F_ACC_RDWR, acc_tpl1);
    assert(fid1 != FAIL);
    MESG("H5Fopen succeed");

    /* Release file-access template */
    ret = H5Pclose(acc_tpl1);
    assert(ret != FAIL);

    /* --------------------------
     * Open the datasets in it
     * ------------------------- */
    /* open the dataset1 collectively */
    dataset1 = H5Dopen2(fid1, DATASETNAME1, H5P_DEFAULT);
    assert(dataset1 != FAIL);
    MESG("H5Dopen2 succeed");

    /* open another dataset collectively */
    dataset2 = H5Dopen2(fid1, DATASETNAME1, H5P_DEFAULT);
    assert(dataset2 != FAIL);
    MESG("H5Dopen2 2 succeed");

    /*
     * Set up dimensions of the slab this process accesses.
     */

    /* Dataset1: each process takes a block of columns. */
    slab_set(start, count, stride, BYCOL);
    if (verbose)
        printf("start[]=(%lu,%lu), count[]=(%lu,%lu), total datapoints=%lu\n", (unsigned long)start[0],
               (unsigned long)start[1], (unsigned long)count[0], (unsigned long)count[1],
               (unsigned long)(count[0] * count[1]));

    /* create a file dataspace independently */
    file_dataspace = H5Dget_space(dataset1);
    assert(file_dataspace != FAIL);
    MESG("H5Dget_space succeed");
    ret = H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL);
    assert(ret != FAIL);
    MESG("H5Sset_hyperslab succeed");

    /* create a memory dataspace independently */
    mem_dataspace = H5Screate_simple(SPACE1_RANK, count, NULL);
    assert(mem_dataspace != FAIL);

    /* fill dataset with test data */
    dataset_fill(start, count, stride, &data_origin1[0][0]);
    MESG("data_array initialized");
    if (verbose) {
        MESG("data_array created");
        dataset_print(start, count, stride, &data_array1[0][0]);
    }

    /* set up the collective transfer properties list */
    xfer_plist = H5Pcreate(H5P_DATASET_XFER);
    assert(xfer_plist != FAIL);
    ret = H5Pset_dxpl_mpio(xfer_plist, H5FD_MPIO_COLLECTIVE);
    assert(ret != FAIL);
    MESG("H5Pcreate xfer succeed");

    /* read data collectively */
    ret = H5Dread(dataset1, H5T_NATIVE_INT, mem_dataspace, file_dataspace, xfer_plist, data_array1);
    assert(ret != FAIL);
    MESG("H5Dread succeed");

    /* verify the read data with original expected data */
    ret = dataset_vrfy(start, count, stride, &data_array1[0][0], &data_origin1[0][0]);
    assert(ret != FAIL);

    /* release all temporary handles. */
    /* Could have used them for dataset2 but it is cleaner */
    /* to create them again.*/
    H5Sclose(file_dataspace);
    H5Sclose(mem_dataspace);
    H5Pclose(xfer_plist);

    /* Dataset2: each process takes a block of rows. */
    slab_set(start, count, stride, BYROW);
    if (verbose)
        printf("start[]=(%lu,%lu), count[]=(%lu,%lu), total datapoints=%lu\n", (unsigned long)start[0],
               (unsigned long)start[1], (unsigned long)count[0], (unsigned long)count[1],
               (unsigned long)(count[0] * count[1]));

    /* create a file dataspace independently */
    file_dataspace = H5Dget_space(dataset1);
    assert(file_dataspace != FAIL);
    MESG("H5Dget_space succeed");
    ret = H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL);
    assert(ret != FAIL);
    MESG("H5Sset_hyperslab succeed");

    /* create a memory dataspace independently */
    mem_dataspace = H5Screate_simple(SPACE1_RANK, count, NULL);
    assert(mem_dataspace != FAIL);

    /* fill dataset with test data */
    dataset_fill(start, count, stride, &data_origin1[0][0]);
    MESG("data_array initialized");
    if (verbose) {
        MESG("data_array created");
        dataset_print(start, count, stride, &data_array1[0][0]);
    }

    /* set up the collective transfer properties list */
    xfer_plist = H5Pcreate(H5P_DATASET_XFER);
    assert(xfer_plist != FAIL);
    ret = H5Pset_dxpl_mpio(xfer_plist, H5FD_MPIO_COLLECTIVE);
    assert(ret != FAIL);
    MESG("H5Pcreate xfer succeed");

    /* read data independently */
    ret = H5Dread(dataset2, H5T_NATIVE_INT, mem_dataspace, file_dataspace, xfer_plist, data_array1);
    assert(ret != FAIL);
    MESG("H5Dread succeed");

    /* verify the read data with original expected data */
    ret = dataset_vrfy(start, count, stride, &data_array1[0][0], &data_origin1[0][0]);
    assert(ret != FAIL);

    /* release all temporary handles. */
    H5Sclose(file_dataspace);
    H5Sclose(mem_dataspace);
    H5Pclose(xfer_plist);

    /*
     * All reads completed.  Close datasets collectively
     */
    ret = H5Dclose(dataset1);
    assert(ret != FAIL);
    MESG("H5Dclose1 succeed");
    ret = H5Dclose(dataset2);
    assert(ret != FAIL);
    MESG("H5Dclose2 succeed");

    /* close the file collectively */
    H5Fclose(fid1);
}

/*
 * test file access by communicator besides COMM_WORLD.
 * Split COMM_WORLD into two, one (even_comm) contains the original
 * processes of even ranks.  The other (odd_comm) contains the original
 * processes of odd ranks.  Processes in even_comm creates a file, then
 * cloose it, using even_comm.  Processes in old_comm just do a barrier
 * using odd_comm.  Then they all do a barrier using COMM_WORLD.
 * If the file creation and cloose does not do correct collective action
 * according to the communicator argument, the processes will freeze up
 * sooner or later due to barrier mixed up.
 */
void
test_split_comm_access(char filenames[][PATH_MAX])
{
    MPI_Comm comm;
    MPI_Info info = MPI_INFO_NULL;
    int      color, mrc;
    int      newrank, newprocs;
    hid_t    fid;     /* file IDs */
    hid_t    acc_tpl; /* File access properties */
    herr_t   ret;     /* generic return value */

    if (verbose)
        printf("Independent write test on file %s %s\n", filenames[0], filenames[1]);

    color = mpi_rank % 2;
    mrc   = MPI_Comm_split(MPI_COMM_WORLD, color, mpi_rank, &comm);
    assert(mrc == MPI_SUCCESS);
    MPI_Comm_size(comm, &newprocs);
    MPI_Comm_rank(comm, &newrank);

    if (color) {
        /* odd-rank processes */
        mrc = MPI_Barrier(comm);
        assert(mrc == MPI_SUCCESS);
    }
    else {
        /* even-rank processes */
        /* setup file access template */
        acc_tpl = H5Pcreate(H5P_FILE_ACCESS);
        assert(acc_tpl != FAIL);

        /* set Parallel access with communicator */
        ret = H5Pset_fapl_mpio(acc_tpl, comm, info);
        assert(ret != FAIL);

        /* create the file collectively */
        fid = H5Fcreate(filenames[color], H5F_ACC_TRUNC, H5P_DEFAULT, acc_tpl);
        assert(fid != FAIL);
        MESG("H5Fcreate succeed");

        /* Release file-access template */
        ret = H5Pclose(acc_tpl);
        assert(ret != FAIL);

        ret = H5Fclose(fid);
        assert(ret != FAIL);
    }
    if (mpi_rank == 0) {
        mrc = MPI_File_delete(filenames[color], info);
        assert(mrc == MPI_SUCCESS);
    }
}

/*
 * Show command usage
 */
void
usage(void)
{
    printf("Usage: testphdf5 [-f <prefix>] [-r] [-w] [-v]\n");
    printf("\t-f\tfile prefix for parallel test files.\n");
    printf("\t  \t e.g. pfs:/PFS/myname\n");
    printf("\t  \tcan be set via $" PARAPREFIX ".\n");
    printf("\t  \tDefault is current directory.\n");
    printf("\t-c\tno cleanup\n");
    printf("\t-r\tno read\n");
    printf("\t-w\tno write\n");
    printf("\t-v\tverbose on\n");
    printf("\tdefault do write then read\n");
    printf("\n");
}

/*
 * compose the test filename with the prefix supplied.
 * return code: 0 if no error
 *              1 otherwise.
 */
int
mkfilenames(char *prefix)
{
    int    i, n;
    size_t strsize;

    /* filename will be prefix/ParaEgN.h5 where N is 0 to 9. */
    /* So, string must be big enough to hold the prefix, / and 10 more chars */
    /* and the terminating null. */
    strsize = strlen(prefix) + 12;
    if (strsize > PATH_MAX) {
        printf("File prefix too long;  Use a short path name.\n");
        return (1);
    }
    n = sizeof(testfiles) / sizeof(testfiles[0]);
    if (n > 9) {
        printf("Warning: Too many entries in testfiles. "
               "Need to adjust the code to accommodate the large size.\n");
    }
    for (i = 0; i < n; i++) {
        snprintf(testfiles[i], PATH_MAX, "%s/ParaEg%d.h5", prefix, i);
    }
    return (0);
}

/*
 * parse the command line options
 */
int
parse_options(int argc, char **argv)
{
    int i, n;

    /* initialize testfiles to nulls */
    n = sizeof(testfiles) / sizeof(testfiles[0]);
    for (i = 0; i < n; i++) {
        testfiles[i][0] = '\0';
    }

    while (--argc) {
        if (**(++argv) != '-') {
            break;
        }
        else {
            switch (*(*argv + 1)) {
                case 'f':
                    ++argv;
                    if (--argc < 1) {
                        usage();
                        nerrors++;
                        return (1);
                    }
                    if (mkfilenames(*argv)) {
                        nerrors++;
                        return (1);
                    }
                    break;
                case 'c':
                    docleanup = 0; /* no cleanup */
                    break;
                case 'r':
                    doread = 0;
                    break;
                case 'w':
                    dowrite = 0;
                    break;
                case 'v':
                    verbose = 1;
                    break;
                default:
                    usage();
                    nerrors++;
                    return (1);
            }
        }
    }

    /* check the file prefix */
    if (testfiles[0][0] == '\0') {
        /* try get it from environment variable HDF5_PARAPREFIX */
        char *env;
        char *env_default = "."; /* default to current directory */
        if ((env = getenv(PARAPREFIX)) == NULL) {
            env = env_default;
        }
        mkfilenames(env);
    }
    return (0);
}

/*
 * cleanup test files created
 */
void
cleanup(void)
{
    int i, n;

    n = sizeof(testfiles) / sizeof(testfiles[0]);
    for (i = 0; i < n; i++) {
        MPI_File_delete(testfiles[i], MPI_INFO_NULL);
    }
}

/* Main Program */
int
main(int argc, char **argv)
{
    int  mpi_namelen;
    char mpi_name[MPI_MAX_PROCESSOR_NAME];
    int  i, n;

    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);
    MPI_Get_processor_name(mpi_name, &mpi_namelen);
    /* Make sure datasets can be divided into equal chunks by the processes */
    if ((SPACE1_DIM1 % mpi_size) || (SPACE1_DIM2 % mpi_size)) {
        printf("DIM1(%d) and DIM2(%d) must be multiples of processes (%d)\n", SPACE1_DIM1, SPACE1_DIM2,
               mpi_size);
        nerrors++;
        goto finish;
    }

    if (parse_options(argc, argv) != 0)
        goto finish;

    /* show test file names */
    if (mpi_rank == 0) {
        n = sizeof(testfiles) / sizeof(testfiles[0]);
        printf("Parallel test files are:\n");
        for (i = 0; i < n; i++) {
            printf("   %s\n", testfiles[i]);
        }
    }

    if (dowrite) {
        MPI_BANNER("testing PHDF5 dataset using split communicators...");
        test_split_comm_access(testfiles);
        MPI_BANNER("testing PHDF5 dataset independent write...");
        phdf5writeInd(testfiles[0]);
        MPI_BANNER("testing PHDF5 dataset collective write...");
        phdf5writeAll(testfiles[1]);
    }
    if (doread) {
        MPI_BANNER("testing PHDF5 dataset independent read...");
        phdf5readInd(testfiles[0]);
        MPI_BANNER("testing PHDF5 dataset collective read...");
        phdf5readAll(testfiles[1]);
    }

    if (!(dowrite || doread)) {
        usage();
        nerrors++;
    }

finish:
    if (mpi_rank == 0) { /* only process 0 reports */
        if (nerrors)
            printf("***PHDF5 example detected %d errors***\n", nerrors);
        else {
            printf("=====================================\n");
            printf("PHDF5 example finished with no errors\n");
            printf("=====================================\n");
        }
    }
    if (docleanup)
        cleanup();
    MPI_Finalize();

    return (nerrors);
}

#else  /* H5_HAVE_PARALLEL */
/* dummy program since H5_HAVE_PARALLE is not configured in */
int
main(void)
{
    printf("No PHDF5 example because parallel is not configured in\n");
    return (0);
}
#endif /* H5_HAVE_PARALLEL */