mpi_noncontiguous_partitioner.h

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// ---------------------------------------------------------------------
//
// Copyright (C) 2020 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, 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.
// The full text of the license can be found in the file LICENSE.md at
// the top level directory of deal.II.
//
// ---------------------------------------------------------------------

#ifndef dealii_mpi_noncontiguous_partitioner_h
#define dealii_mpi_noncontiguous_partitioner_h

#include <deal.II/base/config.h>

#include <deal.II/base/mpi.h>
#include <deal.II/base/mpi_compute_index_owner_internal.h>
#include <deal.II/base/mpi_tags.h>

#include <deal.II/lac/communication_pattern_base.h>
#include <deal.II/lac/vector_space_vector.h>


DEAL_II_NAMESPACE_OPEN

namespace Utilities
{
  namespace MPI
  {
    class NoncontiguousPartitioner
      : public ::LinearAlgebra::CommunicationPatternBase
    {
    public:
      NoncontiguousPartitioner() = default;

      NoncontiguousPartitioner(const IndexSet &indexset_locally_owned,
                               const IndexSet &indexset_ghost,
                               const MPI_Comm &communicator);

      NoncontiguousPartitioner(
        const std::vector<types::global_dof_index> &indices_locally_owned,
        const std::vector<types::global_dof_index> &indices_ghost,
        const MPI_Comm &                            communicator);

      template <typename Number>
      void
      export_to_ghosted_array(
        const ArrayView<const Number> &locally_owned_array,
        const ArrayView<Number> &      ghost_array) const;

      template <typename Number>
      void
      export_to_ghosted_array(
        const unsigned int             communication_channel,
        const ArrayView<const Number> &locally_owned_array,
        const ArrayView<Number> &      temporary_storage,
        const ArrayView<Number> &      ghost_array,
        std::vector<MPI_Request> &     requests) const;

      template <typename Number>
      void
      export_to_ghosted_array_start(
        const unsigned int             communication_channel,
        const ArrayView<const Number> &locally_owned_array,
        const ArrayView<Number> &      temporary_storage,
        std::vector<MPI_Request> &     requests) const;

      template <typename Number>
      void
      export_to_ghosted_array_finish(
        const ArrayView<const Number> &temporary_storage,
        const ArrayView<Number> &      ghost_array,
        std::vector<MPI_Request> &     requests) const;

      std::pair<unsigned int, unsigned int>
      n_targets();

      types::global_dof_index
      memory_consumption();

      const MPI_Comm &
      get_mpi_communicator() const override;

      void
      reinit(const IndexSet &indexset_locally_owned,
             const IndexSet &indexset_ghost,
             const MPI_Comm &communicator) override;

      void
      reinit(const std::vector<types::global_dof_index> &indices_locally_owned,
             const std::vector<types::global_dof_index> &indices_ghost,
             const MPI_Comm &                            communicator);

    private:
      MPI_Comm communicator;

      std::vector<unsigned int> send_ranks;

      std::vector<types::global_dof_index> send_ptr;

      std::vector<types::global_dof_index> send_indices;

      std::vector<unsigned int> recv_ranks;

      std::vector<types::global_dof_index> recv_ptr;

      std::vector<types::global_dof_index> recv_indices;

      mutable std::vector<uint8_t> buffers;

      mutable std::vector<MPI_Request> requests;
    };

  } // namespace MPI
} // namespace Utilities

DEAL_II_NAMESPACE_CLOSE

#endif