MPIRestrictor.h

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/***************************************************************************
 *  ThunderEgg, a library for solvers on adaptively refined block-structured
 *  Cartesian grids.
 *
 *  Copyright (c) 2020-2021 Scott Aiton
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 ***************************************************************************/
 
#ifndef THUNDEREGG_GMG_MPIRESTRICTOR_H
#define THUNDEREGG_GMG_MPIRESTRICTOR_H
 
#include <ThunderEgg/Domain.h>
#include <ThunderEgg/GMG/InterLevelComm.h>
#include <ThunderEgg/GMG/Level.h>
#include <ThunderEgg/GMG/Restrictor.h>
namespace ThunderEgg::GMG {
template<int D>
class MPIRestrictor : public Restrictor<D>
{
private:
  mutable InterLevelComm<D> ilc;
 
public:
  MPIRestrictor(const Domain<D>& coarser_domain, const Domain<D>& finer_domain)
    : ilc(coarser_domain, finer_domain)
  {}
  Vector<D> restrict(const Vector<D>& fine) const override
  {
    if constexpr (ENABLE_DEBUG) {
      if (fine.getNumLocalPatches() != ilc.getFinerDomain().getNumLocalPatches()) {
        throw RuntimeError("fine vector is incorrect length. Expected Length of " +
                           std::to_string(ilc.getFinerDomain().getNumLocalPatches()) +
                           " but vector was length " + std::to_string(fine.getNumLocalPatches()));
      }
    }
    Vector<D> coarse(ilc.getCoarserDomain(), fine.getNumComponents());
    Vector<D> coarse_ghost = ilc.getNewGhostVector(fine.getNumComponents());
 
    // fill in ghost values
    restrictPatches(ilc.getPatchesWithGhostParent(), fine, coarse_ghost);
 
    // clear values in coarse vector
    coarse.setWithGhost(0);
 
    // start scatter for ghost values
    ilc.sendGhostPatchesStart(coarse, coarse_ghost);
 
    // fill in local values
    restrictPatches(ilc.getPatchesWithLocalParent(), fine, coarse);
 
    // finish scatter for ghost values
    ilc.sendGhostPatchesFinish(coarse, coarse_ghost);
 
    return coarse;
  }
  virtual void restrictPatches(
    const std::vector<std::pair<int, std::reference_wrapper<const PatchInfo<D>>>>& patches,
    const Vector<D>& finer_vector,
    Vector<D>& coarser_vector) const = 0;
};
} // namespace ThunderEgg::GMG
// explicit instantiation
extern template class ThunderEgg::GMG::MPIRestrictor<2>;
extern template class ThunderEgg::GMG::MPIRestrictor<3>;
#endif