HDF5_reader_vd.hpp

/*
 * HDF5_reader_vd.hpp
 *
 *  Created on: May 1, 2017
 *      Author: i-bird
 */

#ifndef OPENFPM_IO_SRC_HDF5_WR_HDF5_READER_VD_HPP_
#define OPENFPM_IO_SRC_HDF5_WR_HDF5_READER_VD_HPP_


template <>
class HDF5_reader<VECTOR_DIST>
{
private:

    template<unsigned int dim, typename St,typename prp>
    bool load_block(long int bid,
                    hssize_t mpi_size_old,
                    int * metadata_out,
                    openfpm::vector<size_t> metadata_accum,
                    hid_t plist_id,
                    hid_t dataset_2,
                    size_t & g_m,
                    openfpm::vector<Point<dim,St>> & v_pos,
                    openfpm::vector<prp> & v_prp)
    {
        hsize_t offset[1];
        hsize_t block[1];

        if (bid < mpi_size_old && bid != -1)
        {
            offset[0] = metadata_accum.get(bid);
            block[0] = metadata_out[bid];
        }
        else
        {
            offset[0] = 0;
            block[0] = 0;
        }

        hsize_t count[1] = {1};


        //Select file dataspace
        hid_t file_dataspace_id_2 = H5Dget_space(dataset_2);
        if (file_dataspace_id_2 < 0)    {return false;}

        herr_t err = H5Sselect_hyperslab(file_dataspace_id_2, H5S_SELECT_SET, offset, NULL, count, block);
        if (err < 0)    {return false;}

        hsize_t mdim_2[1] = {block[0]};


        //Create data space in memory
        hid_t mem_dataspace_id_2 = H5Screate_simple(1, mdim_2, NULL);
        if (mem_dataspace_id_2 < 0) {return false;}

        size_t sum = 0;

        for (int i = 0; i < mpi_size_old; i++)
            sum += metadata_out[i];

        // allocate the memory
        HeapMemory pmem;

        ExtPreAlloc<HeapMemory> & mem = *(new ExtPreAlloc<HeapMemory>(block[0],pmem));
        mem.incRef();

        // Read the dataset.
        err = H5Dread(dataset_2, H5T_NATIVE_CHAR, mem_dataspace_id_2, file_dataspace_id_2, plist_id, (char *)mem.getPointer());
        if (err < 0)    {return false;}

        mem.allocate(pmem.size());

        Unpack_stat ps;

        openfpm::vector<Point<dim, St>> v_pos_unp;

        openfpm::vector<prp> v_prp_unp;

        Unpacker<decltype(v_pos_unp),HeapMemory>::unpack(mem,v_pos_unp,ps,1);
        Unpacker<decltype(v_prp_unp),HeapMemory>::unpack(mem,v_prp_unp,ps,1);

        mem.decRef();
        delete &mem;

        for (size_t i = 0; i < v_pos_unp.size(); i++)
            v_pos.add(v_pos_unp.get(i));

        for (size_t i = 0; i < v_prp_unp.size(); i++)
            v_prp.add(v_prp_unp.get(i));

        g_m = v_pos.size();

        H5Sclose(file_dataspace_id_2);
        H5Sclose(mem_dataspace_id_2);

        return true;
    }

public:

    template<unsigned int dim, typename St, typename prp> inline bool load(const std::string & filename,
                                                                           openfpm::vector<Point<dim,St>> & v_pos,
                                                                           openfpm::vector<prp> & v_prp,
                                                                           size_t & g_m)
    {
        Vcluster & v_cl = create_vcluster();

        v_pos.clear();
        v_prp.clear();

        g_m = 0;

        MPI_Comm comm = v_cl.getMPIComm();
        MPI_Info info  = MPI_INFO_NULL;

        int mpi_rank = v_cl.getProcessUnitID();

        // Set up file access property list with parallel I/O access
        hid_t plist_id = H5Pcreate(H5P_FILE_ACCESS);
        if (plist_id == -1) {return false;}
        herr_t err = H5Pset_fapl_mpio(plist_id, comm, info);
        if (err < 0)
            return false;

        //Open a file
        hid_t file = H5Fopen (filename.c_str(), H5F_ACC_RDONLY, plist_id);
        if (file < 0)   {return false;}
        H5Pclose(plist_id);

        //Open dataset
        hid_t dataset = H5Dopen (file, "metadata", H5P_DEFAULT);
        if (dataset < 0)    {return false;}

        //Create property list for collective dataset read
        plist_id = H5Pcreate(H5P_DATASET_XFER);
        if (plist_id == -1) {return false;}
        H5Pset_dxpl_mpio(plist_id, H5FD_MPIO_COLLECTIVE);

        //Select file dataspace
        hid_t file_dataspace_id = H5Dget_space(dataset);
        if (file_dataspace_id < 0)  {return false;}

        hssize_t mpi_size_old = H5Sget_select_npoints (file_dataspace_id);
        if (mpi_size_old < 0)   {return false;}

        //Where to read metadata
        int metadata_out[mpi_size_old];

        for (int i = 0; i < mpi_size_old; i++)
        {metadata_out[i] = 0;}

        //Size for data space in memory
        hsize_t mdim[1] = {(size_t)mpi_size_old};

        //Create data space in memory
        hid_t mem_dataspace_id = H5Screate_simple(1, mdim, NULL);
        if (mem_dataspace_id < 0)   {return false;}

        // Read the dataset.
        err = H5Dread(dataset, H5T_NATIVE_INT, mem_dataspace_id, file_dataspace_id, plist_id, metadata_out);
        if (err < 0)    {return false;}

        openfpm::vector<size_t> metadata_accum;
        metadata_accum.resize(mpi_size_old);

        metadata_accum.get(0) = 0;
        for (int i = 1 ; i < mpi_size_old ; i++)
            metadata_accum.get(i) = metadata_accum.get(i-1) + metadata_out[i-1];

        //Open dataset
        hid_t dataset_2 = H5Dopen (file, "vector_dist", H5P_DEFAULT);
        if (dataset_2 < 0)  {return false;}

        //Create property list for collective dataset read
        plist_id = H5Pcreate(H5P_DATASET_XFER);
        if (plist_id == -1) {return false;}

        err = H5Pset_dxpl_mpio(plist_id, H5FD_MPIO_COLLECTIVE);
        if (err < 0)    {return false;}

        openfpm::vector<size_t> n_block;
        n_block.resize(v_cl.getProcessingUnits());


        for(size_t i = 0 ; i < n_block.size() ; i++)
            n_block.get(i) = mpi_size_old / v_cl.getProcessingUnits();

        size_t rest_block = mpi_size_old % v_cl.getProcessingUnits();

        size_t max_block;

        if (rest_block != 0)
            max_block = n_block.get(0) + 1;
        else
            max_block = n_block.get(0);

        //for(size_t i = 0 ; i < n_block.size() ; i++)
        for(size_t i = 0 ; i < rest_block ; i++)
            n_block.get(i) += 1;

        size_t start_block = 0;
        size_t stop_block = 0;


        if (v_cl.getProcessUnitID() != 0)
        {
            for(size_t i = 0 ; i < v_cl.getProcessUnitID() ; i++)
                start_block += n_block.get(i);
        }

        stop_block = start_block + n_block.get(v_cl.getProcessUnitID());

        if (mpi_rank >= mpi_size_old)
            load_block(start_block,mpi_size_old,metadata_out,metadata_accum,plist_id,dataset_2,g_m,v_pos,v_prp);
        else
        {
            size_t n_bl = 0;
            size_t lb = start_block;
            for ( ; lb < stop_block ; lb++, n_bl++)
                load_block(lb,mpi_size_old,metadata_out,metadata_accum,plist_id,dataset_2,g_m,v_pos,v_prp);

            if (n_bl < max_block)
                load_block(-1,mpi_size_old,metadata_out,metadata_accum,plist_id,dataset_2,g_m,v_pos,v_prp);
        }

        // Close open object
        H5Sclose(mem_dataspace_id);
        H5Sclose(file_dataspace_id);
        // Close the dataset.
        H5Dclose(dataset);
        H5Dclose(dataset_2);
        // Close the file.
        H5Fclose(file);
        H5Pclose(plist_id);

        return true;
    }
};


#endif /* OPENFPM_IO_SRC_HDF5_WR_HDF5_READER_VD_HPP_ */