3_write_serial.cpp

/* Copyright 2017-2021 Fabian Koller, Axel Huebl
 *
 * This file is part of openPMD-api.
 *
 * openPMD-api is free software: you can redistribute it and/or modify
 * it under the terms of of either the GNU General Public License or
 * the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * openPMD-api is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License and the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * and the GNU Lesser General Public License along with openPMD-api.
 * If not, see <http://www.gnu.org/licenses/>.
 */
#include <openPMD/openPMD.hpp>

#include <cstdlib>
#include <iostream>
#include <memory>
#include <numeric>

using std::cout;
using namespace openPMD;

int main(int argc, char *argv[])
{
    // user input: size of matrix to write, default 3x3
    size_t size = (argc == 2 ? atoi(argv[1]) : 3);

    // matrix dataset to write with values 0...size*size-1
    std::vector<double> global_data(size * size);
    std::iota(global_data.begin(), global_data.end(), 0.);

    cout << "Set up a 2D square array (" << size << 'x' << size
         << ") that will be written\n";

    // open file for writing
    Series series = Series("../samples/3_write_serial.h5", Access::CREATE);
    cout << "Created an empty " << series.iterationEncoding() << " Series\n";

    // `Series::writeIterations()` and `Series::readIterations()` are
    // intentionally restricted APIs that ensure a workflow which also works
    // in streaming setups, e.g. an iteration cannot be opened again once
    // it has been closed.
    // `Series::iterations` can be directly accessed in random-access workflows.
    Mesh rho = series.writeIterations()[1].meshes["rho"];
    cout << "Created a scalar mesh Record with all required openPMD "
            "attributes\n";

    Datatype datatype = determineDatatype(global_data.data());
    Extent extent = {size, size};
    Dataset dataset = Dataset(datatype, extent);
    cout << "Created a Dataset of size " << dataset.extent[0] << 'x'
         << dataset.extent[1] << " and Datatype " << dataset.dtype << '\n';

    rho.resetDataset(dataset);
    cout << "Set the dataset properties for the scalar field rho in iteration "
            "1\n";

    series.flush();
    cout << "File structure and required attributes have been written\n";

    Offset offset = {0, 0};
    rho.storeChunk(global_data, offset, extent);
    cout << "Stored the whole Dataset contents as a single chunk, "
            "ready to write content\n";

    // The iteration can be closed in order to help free up resources.
    // The iteration's content will be flushed automatically.
    // An iteration once closed cannot (yet) be reopened.
    series.writeIterations()[1].close();

    cout << "Dataset content has been fully written\n";

    /* The files in 'series' are still open until the object is destroyed, on
     * which it cleanly flushes and closes all open file handles.
     * When running out of scope on return, the 'Series' destructor is called.
     * Alternatively, one can call `series.close()` to the same effect as
     * calling the destructor, including the release of file handles.
     */
    series.close();
    return 0;
}