process_grid.h

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2017 - 2026 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Detailed license information governing the source code and contributions
// can be found in LICENSE.md and CONTRIBUTING.md at the top level directory.
//
// -----------------------------------------------------------------------------
 
#ifndef dealii_process_grid_h
#define dealii_process_grid_h
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/exceptions.h>
#include <deal.II/base/mpi.h>
 
DEAL_II_NAMESPACE_OPEN
 
#ifdef DEAL_II_WITH_SCALAPACK
// Forward declaration of class ScaLAPACKMatrix for ProcessGrid
#  ifndef DOXYGEN
template <typename NumberType>
class ScaLAPACKMatrix;
#  endif
 
namespace Utilities
{
  namespace MPI
  {
    class ProcessGrid
    {
    public:
      // Declare class ScaLAPACK as friend to provide access to private members.
      template <typename NumberType>
      friend class ::ScaLAPACKMatrix;
 
      ProcessGrid(const MPI_Comm     mpi_communicator,
                  const unsigned int n_rows,
                  const unsigned int n_columns);
 
      ProcessGrid(const MPI_Comm     mpi_communicator,
                  const unsigned int n_rows_matrix,
                  const unsigned int n_columns_matrix,
                  const unsigned int row_block_size,
                  const unsigned int column_block_size);
 
      ~ProcessGrid();
 
      unsigned int
      get_process_grid_rows() const;
 
      unsigned int
      get_process_grid_columns() const;
 
      int
      get_this_process_row() const;
 
      int
      get_this_process_column() const;
 
      template <typename NumberType>
      void
      send_to_inactive(NumberType *value, const int count = 1) const;
 
      bool
      is_process_active() const;
 
    private:
      ProcessGrid(const MPI_Comm                               mpi_communicator,
                  const std::pair<unsigned int, unsigned int> &grid_dimensions);
 
      MPI_Comm mpi_communicator;
 
      MPI_Comm mpi_communicator_inactive_with_root;
 
      int blacs_context;
 
      const unsigned int this_mpi_process;
 
      const unsigned int n_mpi_processes;
 
      int n_process_rows;
 
      int n_process_columns;
 
      int this_process_row;
 
      int this_process_column;
 
      bool mpi_process_is_active;
    };
 
    /*--------------------- Inline functions --------------------------------*/
 
#  ifndef DOXYGEN
 
    inline unsigned int
    ProcessGrid::get_process_grid_rows() const
    {
      return n_process_rows;
    }
 
 
 
    inline unsigned int
    ProcessGrid::get_process_grid_columns() const
    {
      return n_process_columns;
    }
 
 
 
    inline int
    ProcessGrid::get_this_process_row() const
    {
      return this_process_row;
    }
 
 
 
    inline int
    ProcessGrid::get_this_process_column() const
    {
      return this_process_column;
    }
 
 
 
    inline bool
    ProcessGrid::is_process_active() const
    {
      return mpi_process_is_active;
    }
 
 
#  endif // ifndef DOXYGEN
 
  } // end of namespace MPI
 
} // end of namespace Utilities
 
#endif // DEAL_II_WITH_SCALAPACK
 
DEAL_II_NAMESPACE_CLOSE
 
#endif