parmetis_helper.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2025 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner

// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.

// This library 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
// Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#ifndef LIBMESH_PARMETIS_HELPER_H
#define LIBMESH_PARMETIS_HELPER_H

// Local Includes
#include "libmesh/libmesh_config.h"

// C++ Includes
#include <vector>

#ifdef LIBMESH_HAVE_PARMETIS

#include "libmesh/id_types.h"

// Before we include a header wrapped in a namespace, we'd better make
// sure none of its dependencies end up in that namespace
#include <mpi.h>

// Include the ParMETIS header files.  We need this so we can use
// ParMetis' idx_t and real_t types directly.
namespace Parmetis {
extern "C" {
#     include "libmesh/ignore_warnings.h"
#     include "parmetis.h"
#     include "libmesh/restore_warnings.h"
}
}
#endif // LIBMESH_HAVE_PARMETIS


namespace libMesh
{

class ParmetisHelper
{
public:
  ParmetisHelper () = default;
  ParmetisHelper (const ParmetisHelper &) = default;
  ParmetisHelper (ParmetisHelper &&) = default;
  ParmetisHelper & operator= (const ParmetisHelper &) = default;
  ParmetisHelper & operator= (ParmetisHelper &&) = default;
  ~ParmetisHelper () = default;

#ifdef LIBMESH_HAVE_PARMETIS

  std::vector<Parmetis::idx_t>  vtxdist;
  std::vector<Parmetis::idx_t>  xadj;
  std::vector<Parmetis::idx_t>  adjncy;

  // We use dof_id_type for part so we can pass it directly to
  // Partitioner:: methods expecting that type.
  std::vector<dof_id_type>  part;

  // But we plan to pass a pointer to part as a buffer to ParMETIS, so
  // it had better be using a simply reinterpretable type!
  static_assert(sizeof(Parmetis::idx_t) == sizeof(dof_id_type),
                "ParMETIS and libMesh ID sizes must match!");

  std::vector<Parmetis::real_t> tpwgts;
  std::vector<Parmetis::real_t> ubvec;
  std::vector<Parmetis::idx_t>  options;
  std::vector<Parmetis::idx_t>  vwgt;

  Parmetis::idx_t wgtflag;
  Parmetis::idx_t ncon;
  Parmetis::idx_t numflag;
  Parmetis::idx_t nparts;
  Parmetis::idx_t edgecut;

#endif // LIBMESH_HAVE_PARMETIS
};

} // namespace libMesh

#endif // LIBMESH_PARMETIS_HELPER_H