path: root/examples/h5_vds-percival-unlim-maxmin.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * 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://support.hdfgroup.org/ftp/HDF5/releases.  *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/************************************************************

  This example illustrates the concept of the virtual dataset.
  Percival use case. Every fifth 10x10 plane in VDS is stored in
  the corresponding 3D unlimited dataset.
  There are 4 source datasets total.
  Each of the source datasets is extended to different sizes.
  VDS access property can be used to get max and min extent.
  This file is intended for use with HDF5 Library version 1.10

 ************************************************************/
/* EIP Add link to the picture */

#include "hdf5.h"
#include <stdio.h>
#include <stdlib.h>

#define VFILE   "vds-percival-unlim-maxmin.h5"
#define DATASET "VDS-Percival-unlim-maxmin"
#define VDSDIM0 H5S_UNLIMITED
#define VDSDIM1 10
#define VDSDIM2 10

#define DIM0         H5S_UNLIMITED
#define DIM0_1       4 /* Initial size of the source datasets */
#define DIM1         10
#define DIM2         10
#define RANK         3
#define PLANE_STRIDE 4

const char *SRC_FILE[] = {"a.h5", "b.h5", "c.h5", "d.h5"};

const char *SRC_DATASET[] = {"A", "B", "C", "D"};

int
main(void)
{
    hid_t   vfile, file, src_space, mem_space, vspace, vdset, dset; /* Handles */
    hid_t   dcpl, dapl;
    herr_t  status;
    hsize_t vdsdims[3] = {4 * DIM0_1, VDSDIM1, VDSDIM2}, vdsdims_max[3] = {VDSDIM0, VDSDIM1, VDSDIM2},
            dims[3] = {DIM0_1, DIM1, DIM2}, memdims[3] = {DIM0_1, DIM1, DIM2},
            extdims[3] = {0, DIM1, DIM2}, /* Dimensions of the extended source datasets */
        chunk_dims[3] = {DIM0_1, DIM1, DIM2}, dims_max[3] = {DIM0, DIM1, DIM2}, vdsdims_out[3],
            vdsdims_max_out[3], start[3], /* Hyperslab parameters */
        stride[3], count[3], src_count[3], block[3];
    hsize_t start_out[3], /* Hyperslab parameter out */
        stride_out[3], count_out[3], block_out[3];
    int          i, j;
    H5D_layout_t layout;  /* Storage layout */
    size_t       num_map; /* Number of mappings */
    ssize_t      len;     /* Length of the string; also a return value */
    char *       filename;
    char *       dsetname;
    int          wdata[DIM0_1 * DIM1 * DIM2];

    /*
     * Create source files and datasets. This step is optional.
     */
    for (i = 0; i < PLANE_STRIDE; i++) {
        /*
         * Initialize data for i-th source dataset.
         */
        for (j = 0; j < DIM0_1 * DIM1 * DIM2; j++)
            wdata[j] = i + 1;

        /*
         * Create the source files and  datasets. Write data to each dataset and
         * close all resources.
         */

        file      = H5Fcreate(SRC_FILE[i], H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
        src_space = H5Screate_simple(RANK, dims, dims_max);
        dcpl      = H5Pcreate(H5P_DATASET_CREATE);
        status    = H5Pset_chunk(dcpl, RANK, chunk_dims);
        dset   = H5Dcreate2(file, SRC_DATASET[i], H5T_NATIVE_INT, src_space, H5P_DEFAULT, dcpl, H5P_DEFAULT);
        status = H5Dwrite(dset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, wdata);
        status = H5Sclose(src_space);
        status = H5Pclose(dcpl);
        status = H5Dclose(dset);
        status = H5Fclose(file);
    }

    vfile = H5Fcreate(VFILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);

    /* Create VDS dataspace.  */
    vspace = H5Screate_simple(RANK, vdsdims, vdsdims_max);

    /* Create dataspaces for the source dataset. */
    src_space = H5Screate_simple(RANK, dims, dims_max);

    /* Create VDS creation property */
    dcpl = H5Pcreate(H5P_DATASET_CREATE);

    /* Initialize hyperslab values */

    start[0]     = 0;
    start[1]     = 0;
    start[2]     = 0;
    stride[0]    = PLANE_STRIDE; /* we will select every fifth plane in VDS */
    stride[1]    = 1;
    stride[2]    = 1;
    count[0]     = H5S_UNLIMITED;
    count[1]     = 1;
    count[2]     = 1;
    src_count[0] = H5S_UNLIMITED;
    src_count[1] = 1;
    src_count[2] = 1;
    block[0]     = 1;
    block[1]     = DIM1;
    block[2]     = DIM2;

    /*
     * Build the mappings
     *
     */
    status = H5Sselect_hyperslab(src_space, H5S_SELECT_SET, start, NULL, src_count, block);
    for (i = 0; i < PLANE_STRIDE; i++) {
        status = H5Sselect_hyperslab(vspace, H5S_SELECT_SET, start, stride, count, block);
        status = H5Pset_virtual(dcpl, vspace, SRC_FILE[i], SRC_DATASET[i], src_space);
        start[0]++;
    }

    H5Sselect_none(vspace);

    /* Create a virtual dataset */
    vdset  = H5Dcreate2(vfile, DATASET, H5T_NATIVE_INT, vspace, H5P_DEFAULT, dcpl, H5P_DEFAULT);
    status = H5Sclose(vspace);
    status = H5Sclose(src_space);
    status = H5Pclose(dcpl);

    /* Let's add data to the source datasets and check new dimensions for VDS */
    /* We will add only one plane to the first source dataset, two planes to the
       second one, three to the third, and four to the forth.                 */

    for (i = 0; i < PLANE_STRIDE; i++) {
        /*
         * Initialize data for i-th source dataset.
         */
        for (j = 0; j < (i + 1) * DIM1 * DIM2; j++)
            wdata[j] = 10 * (i + 1);

        /*
         * Open the source files and datasets. Appen data to each dataset and
         * close all resources.
         */

        file       = H5Fopen(SRC_FILE[i], H5F_ACC_RDWR, H5P_DEFAULT);
        dset       = H5Dopen2(file, SRC_DATASET[i], H5P_DEFAULT);
        extdims[0] = DIM0_1 + i + 1;
        status     = H5Dset_extent(dset, extdims);
        src_space  = H5Dget_space(dset);
        start[0]   = DIM0_1;
        start[1]   = 0;
        start[2]   = 0;
        count[0]   = 1;
        count[1]   = 1;
        count[2]   = 1;
        block[0]   = i + 1;
        block[1]   = DIM1;
        block[2]   = DIM2;

        memdims[0] = i + 1;
        mem_space  = H5Screate_simple(RANK, memdims, NULL);
        status     = H5Sselect_hyperslab(src_space, H5S_SELECT_SET, start, NULL, count, block);
        status     = H5Dwrite(dset, H5T_NATIVE_INT, mem_space, src_space, H5P_DEFAULT, wdata);
        status     = H5Sclose(src_space);
        status     = H5Dclose(dset);
        status     = H5Fclose(file);
    }

    status = H5Dclose(vdset);
    status = H5Fclose(vfile);

    /*
     * Now we begin the read section of this example.
     */

    /*
     * Open file and dataset using the default properties.
     */
    vfile = H5Fopen(VFILE, H5F_ACC_RDONLY, H5P_DEFAULT);

    /*
     * Open VDS using different access properties to use max or
     * min extents depending on the sizes of the underlying datasets
     */
    dapl = H5Pcreate(H5P_DATASET_ACCESS);

    for (i = 0; i < 2; i++) {
        status = H5Pset_virtual_view(dapl, i ? H5D_VDS_LAST_AVAILABLE : H5D_VDS_FIRST_MISSING);
        vdset  = H5Dopen2(vfile, DATASET, dapl);

        /* Let's get space of the VDS and its dimension; we should get 32(or 20)x10x10 */
        vspace = H5Dget_space(vdset);
        H5Sget_simple_extent_dims(vspace, vdsdims_out, vdsdims_max_out);
        printf("VDS dimensions, bounds = H5D_VDS_%s: ", i ? "LAST_AVAILABLE" : "FIRST_MISSING");
        for (j = 0; j < RANK; j++)
            printf(" %d ", (int)vdsdims_out[j]);
        printf("\n");

        /* Close */
        status = H5Dclose(vdset);
        status = H5Sclose(vspace);
    }

    status = H5Pclose(dapl);

    vdset = H5Dopen2(vfile, DATASET, H5P_DEFAULT);

    /*
     * Get creation property list and mapping properties.
     */
    dcpl = H5Dget_create_plist(vdset);

    /*
     * Get storage layout.
     */
    layout = H5Pget_layout(dcpl);

    if (H5D_VIRTUAL == layout)
        printf(" Dataset has a virtual layout \n");
    else
        printf(" Wrong layout found \n");

    /*
     * Find number of mappings.
     */
    status = H5Pget_virtual_count(dcpl, &num_map);
    printf(" Number of mappings is %lu\n", (unsigned long)num_map);

    /*
     * Get mapping parameters for each mapping.
     */
    for (i = 0; i < (int)num_map; i++) {
        printf(" Mapping %d \n", i);
        printf("         Selection in the virtual dataset \n");
        /* Get selection in the virttual  dataset */
        vspace = H5Pget_virtual_vspace(dcpl, (size_t)i);
        if (H5Sget_select_type(vspace) == H5S_SEL_HYPERSLABS) {
            if (H5Sis_regular_hyperslab(vspace)) {
                status = H5Sget_regular_hyperslab(vspace, start_out, stride_out, count_out, block_out);
                printf("         start  = [%llu, %llu, %llu] \n", (unsigned long long)start_out[0],
                       (unsigned long long)start_out[1], (unsigned long long)start_out[2]);
                printf("         stride = [%llu, %llu, %llu] \n", (unsigned long long)stride_out[0],
                       (unsigned long long)stride_out[1], (unsigned long long)stride_out[2]);
                printf("         count  = [%llu, %llu, %llu] \n", (unsigned long long)count_out[0],
                       (unsigned long long)count_out[1], (unsigned long long)count_out[2]);
                printf("         block  = [%llu, %llu, %llu] \n", (unsigned long long)block_out[0],
                       (unsigned long long)block_out[1], (unsigned long long)block_out[2]);
            }
        }
        /* Get source file name */
        len      = H5Pget_virtual_filename(dcpl, (size_t)i, NULL, 0);
        filename = (char *)malloc((size_t)len * sizeof(char) + 1);
        H5Pget_virtual_filename(dcpl, (size_t)i, filename, len + 1);
        printf("         Source filename %s\n", filename);

        /* Get source dataset name */
        len      = H5Pget_virtual_dsetname(dcpl, (size_t)i, NULL, 0);
        dsetname = (char *)malloc((size_t)len * sizeof(char) + 1);
        H5Pget_virtual_dsetname(dcpl, (size_t)i, dsetname, len + 1);
        printf("         Source dataset name %s\n", dsetname);

        /* Get selection in the source dataset */
        printf("         Selection in the source dataset \n");
        src_space = H5Pget_virtual_srcspace(dcpl, (size_t)i);
        if (H5Sget_select_type(src_space) == H5S_SEL_HYPERSLABS) {
            if (H5Sis_regular_hyperslab(src_space)) {
                status = H5Sget_regular_hyperslab(src_space, start_out, stride_out, count_out, block_out);
                printf("         start  = [%llu, %llu, %llu] \n", (unsigned long long)start_out[0],
                       (unsigned long long)start_out[1], (unsigned long long)start_out[2]);
                printf("         stride = [%llu, %llu, %llu] \n", (unsigned long long)stride_out[0],
                       (unsigned long long)stride_out[1], (unsigned long long)stride_out[2]);
                printf("         count  = [%llu, %llu, %llu] \n", (unsigned long long)count_out[0],
                       (unsigned long long)count_out[1], (unsigned long long)count_out[2]);
                printf("         block  = [%llu, %llu, %llu] \n", (unsigned long long)block_out[0],
                       (unsigned long long)block_out[1], (unsigned long long)block_out[2]);
            }
        }
        H5Sclose(vspace);
        H5Sclose(src_space);
        free(filename);
        free(dsetname);
    }
    /*
     * Close and release resources.
     */
    status = H5Pclose(dcpl);
    status = H5Dclose(vdset);
    status = H5Fclose(vfile);
    return 0;
}