h5par_ex2b.c

/* HDF5 Dataset example, collective metadata modification */

/* System header files */
#include <assert.h>

/* HDF5 header file */
#include "hdf5.h"

/* Predefined names and sizes */
#define FILENAME "h5par_ex2b.h5"
#define DATASETNAME "Dataset 1"
#define RANK    2
#define DIM0    (230 * 1000)
#define DIM1    4       /* Should be same as MPI rank */

int main(int argc, char *argv[])
{
    hid_t file_id;              /* File ID */
    hid_t fapl_id;		/* File access property list */
    hid_t group_id;		/* Group ID */
    hid_t dset_id;		/* Dataset ID */
    hid_t file_space_id;	/* File dataspace ID */
    hsize_t file_dims[RANK];   	/* Dataset dimemsion sizes */
    char groupname[16];         /* Namne of group */
    int mpi_size, mpi_rank;	/* MPI variables */
    int i;                      /* Local index variable */
    herr_t ret;         	/* Generic return value */

    /* Initialize MPI */
    MPI_Init(&argc, &argv);

    /* Gather information about MPI comm size and my rank */
    MPI_Comm_size(MPI_COMM_WORLD, &mpi_size);
    MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

printf("my rank = %d (%d)\n", mpi_rank, mpi_size);

    /* Iniialize buffer of dataset to write */
    /* (in a real application, this would be your science data) */
    /* <SKIPPED> */

    /* Create an HDF5 file access property list */
    fapl_id = H5Pcreate (H5P_FILE_ACCESS);
    assert(fapl_id > 0);

    /* Set file access property list to use the MPI-IO file driver */
    ret = H5Pset_fapl_mpio(fapl_id, MPI_COMM_WORLD, MPI_INFO_NULL);
    assert(ret >= 0);

    /* Create the file collectively */
    file_id = H5Fcreate(FILENAME, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
    assert(file_id > 0);

    /* Release file access property list */
    ret = H5Pclose(fapl_id);
    assert(ret >= 0);

    /* Create all groups & datasets, collectively */
    for(i = 0; i < mpi_size; i++) {

        /* Create one group per rank, independently */
        sprintf(groupname, "Group %d\n", i);
        group_id = H5Gcreate(file_id, groupname, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
        assert(group_id > 0);


        /* Define a file dataspace the dimensions of the dataset */
        file_dims[0] = DIM0;
        file_dims[1] = DIM1;
        file_space_id = H5Screate_simple(RANK, file_dims, NULL);
        assert(file_space_id > 0);

        /* Create the dataset collectively */
        dset_id = H5Dcreate2(group_id, DATASETNAME, H5T_NATIVE_DOUBLE,
            file_space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
        assert(dset_id > 0);


        /* Close file dataspace */
        ret = H5Sclose(file_space_id);
        assert(ret >= 0);

        /* Close dataset collectively */
        ret = H5Dclose(dset_id);
        assert(ret >= 0);

        /* Close group collectively */
        ret = H5Gclose(group_id);
        assert(ret >= 0);
    } /* end for */

    /* Close the file collectively */
    ret = H5Fclose(file_id);
    assert(ret >= 0);

    /* MPI_Finalize must be called AFTER any HDF5 call which may use MPI calls */
    MPI_Finalize();

    return(0);
}