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/*
* This example writes dataset sing chunking. Each process writes
* exactly one chunk.
* - |
* * V
* Number of processes is assumed to be 4.
*/
#include "hdf5.h"
#include "stdlib.h"
#define H5FILE_NAME "SDS_chnk.h5"
#define DATASETNAME "IntArray"
#define NX 8 /* dataset dimensions */
#define NY 4
#define CH_NX 4 /* chunk dimensions */
#define CH_NY 2
#define RANK 2
int
main(int argc, char **argv)
{
/*
* HDF5 APIs definitions
*/
hid_t file_id, dset_id; /* file and dataset identifiers */
hid_t filespace, memspace; /* file and memory dataspace identifiers */
hsize_t dimsf[2]; /* dataset dimensions */
hsize_t chunk_dims[2]; /* chunk dimensions */
int *data; /* pointer to data buffer to write */
hsize_t count[2]; /* hyperslab selection parameters */
hsize_t stride[2];
hsize_t block[2];
hsize_t offset[2];
hid_t plist_id; /* property list identifier */
int i;
herr_t status;
/*
* MPI variables
*/
int mpi_size, mpi_rank;
MPI_Comm comm = MPI_COMM_WORLD;
MPI_Info info = MPI_INFO_NULL;
/*
* Initialize MPI
*/
MPI_Init(&argc, &argv);
MPI_Comm_size(comm, &mpi_size);
MPI_Comm_rank(comm, &mpi_rank);
/*
* Exit if number of processes is not 4.
*/
if (mpi_size != 4) {
printf("This example to set up to use only 4 processes \n");
printf("Quitting...\n");
return 0;
}
/*
* Set up file access property list with parallel I/O access
*/
plist_id = H5Pcreate(H5P_FILE_ACCESS);
H5Pset_fapl_mpio(plist_id, comm, info);
/*
* Create a new file collectively and release property list identifier.
*/
file_id = H5Fcreate(H5FILE_NAME, H5F_ACC_TRUNC, H5P_DEFAULT, plist_id);
H5Pclose(plist_id);
/*
* Create the dataspace for the dataset.
*/
dimsf[0] = NX;
dimsf[1] = NY;
chunk_dims[0] = CH_NX;
chunk_dims[1] = CH_NY;
filespace = H5Screate_simple(RANK, dimsf, NULL);
memspace = H5Screate_simple(RANK, chunk_dims, NULL);
/*
* Create chunked dataset.
*/
plist_id = H5Pcreate(H5P_DATASET_CREATE);
H5Pset_chunk(plist_id, RANK, chunk_dims);
dset_id = H5Dcreate(file_id, DATASETNAME, H5T_NATIVE_INT, filespace, H5P_DEFAULT, plist_id, H5P_DEFAULT);
H5Pclose(plist_id);
H5Sclose(filespace);
/*
* Each process defines dataset in memory and writes it to the hyperslab
* in the file.
*/
count[0] = 1;
count[1] = 1;
stride[0] = 1;
stride[1] = 1;
block[0] = chunk_dims[0];
block[1] = chunk_dims[1];
if (mpi_rank == 0) {
offset[0] = 0;
offset[1] = 0;
}
if (mpi_rank == 1) {
offset[0] = 0;
offset[1] = chunk_dims[1];
}
if (mpi_rank == 2) {
offset[0] = chunk_dims[0];
offset[1] = 0;
}
if (mpi_rank == 3) {
offset[0] = chunk_dims[0];
offset[1] = chunk_dims[1];
}
/*
* Select hyperslab in the file.
*/
filespace = H5Dget_space(dset_id);
status = H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, stride, count, block);
/*
* Initialize data buffer
*/
data = (int *)malloc(sizeof(int) * chunk_dims[0] * chunk_dims[1]);
for (i = 0; i < (int)chunk_dims[0] * chunk_dims[1]; i++) {
data[i] = mpi_rank + 1;
}
/*
* Create property list for collective dataset write.
*/
plist_id = H5Pcreate(H5P_DATASET_XFER);
H5Pset_dxpl_mpio(plist_id, H5FD_MPIO_COLLECTIVE);
status = H5Dwrite(dset_id, H5T_NATIVE_INT, memspace, filespace, plist_id, data);
free(data);
/*
* Close/release resources.
*/
H5Dclose(dset_id);
H5Sclose(filespace);
H5Sclose(memspace);
H5Pclose(plist_id);
H5Fclose(file_id);
if (mpi_rank == 0)
printf("PHDF5 example finished with no errors\n");
MPI_Finalize();
return 0;
}
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