Metis.cpp

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// SPDX-FileCopyrightText: Copyright (c) OpenGeoSys Community (opengeosys.org)
// SPDX-License-Identifier: BSD-3-Clause
 
#include <fstream>
 
#include "BaseLib/Error.h"
#include "MeshLib/Elements/Element.h"
 
namespace ApplicationUtils
{
void writeMETIS(std::vector<MeshLib::Element*> const& elements,
                const std::string& file_name)
{
    std::ofstream os(file_name, std::ios::trunc);
    if (!os.is_open())
    {
        OGS_FATAL("Error: cannot open file {:s}.", file_name.data());
    }
 
    if (!os.good())
    {
        OGS_FATAL("Error: Cannot write in file {:s}.", file_name.data());
    }
 
    os << elements.size() << " \n";
    for (const auto* elem : elements)
    {
        os << getNodeIndex(*elem, 0) + 1;
        for (unsigned j = 1; j < elem->getNumberOfNodes(); j++)
        {
            os << " " << getNodeIndex(*elem, j) + 1;
        }
        os << "\n";
    }
}
 
std::vector<std::size_t> readMetisData(const std::string& file_name_base,
                                       long const number_of_partitions,
                                       std::size_t const number_of_nodes)
{
    const std::string npartitions_str = std::to_string(number_of_partitions);
 
    // Read partitioned mesh data from METIS
    const std::string fname_parts =
        file_name_base + ".mesh.npart." + npartitions_str;
 
    std::ifstream npart_in(fname_parts);
    if (!npart_in.is_open())
    {
        OGS_FATAL(
            "Error: cannot open file {:s}. It may not exist!\n"
            "Run mpmetis beforehand or use option -m",
            fname_parts.data());
    }
 
    std::vector<std::size_t> partition_ids(number_of_nodes);
 
    std::size_t counter = 0;
    while (!npart_in.eof())
    {
        npart_in >> partition_ids[counter++] >> std::ws;
        if (counter == number_of_nodes)
        {
            break;
        }
    }
 
    if (npart_in.bad())
    {
        OGS_FATAL("Error while reading file {:s}.", fname_parts.data());
    }
 
    if (counter != number_of_nodes)
    {
        OGS_FATAL("Error: data in {:s} are less than expected.",
                  fname_parts.data());
    }
 
    return partition_ids;
}
 
void removeMetisPartitioningFiles(std::string const& file_name_base,
                                  long const number_of_partitions)
{
    const std::string npartitions_str = std::to_string(number_of_partitions);
 
    std::remove((file_name_base + ".mesh.npart." + npartitions_str).c_str());
    std::remove((file_name_base + ".mesh.epart." + npartitions_str).c_str());
}
}  // namespace ApplicationUtils