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ParentToChildCellToPointGlobalIdHandle.hpp
//===========================================================================
//
// File: ParentToChildCellToPointGlobalIdHandle.hpp
//
// Created: November 19 2024
//
// Author(s): Antonella Ritorto <antonella.ritorto@opm-op.com>
// Markus Blatt <markus.blatt@opm-op.com>
//
// $Date$
//
// $Revision$
//
//===========================================================================
/*
Copyright 2024 Equinor ASA
This file is part of The Open Porous Media project (OPM).
OPM 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.
OPM 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 OPM. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef OPM_PARENTTOCHILDCELLTOPOINTGLOBALIDHANDLE_HEADER
#define OPM_PARENTTOCHILDCELLTOPOINTGLOBALIDHANDLE_HEADER
#include <opm/grid/common/CommunicationUtils.hpp>
#include <opm/grid/cpgrid/Entity.hpp>
#include <array>
#include <tuple>
#include <vector>
namespace
{
#if HAVE_MPI
struct ParentToChildCellToPointGlobalIdHandle {
// - The container used for gather and scatter contains "candidates" point global ids for interior elements of the refined level grids (LGRs).
// Access is done with the local index of its parent cell index and its parent cell list of children.
// level_point_global_ids[ level-1 ][ child_cell_local_index [ corner ] ] = "candidate" point global id,
// when child_cell_local_index belongs to the children_local_index_list:
// parent_to_children_[ element.index() ] = parent_to_children_[ element.index() ] = { level, children_local_index_list }
// and corner = 0, ...,7.
// To decide which "candidate" point global id wins, we use the rank. The smallest ranks wins,
// i.e., the other non-selected candidates get rewritten with the values from the smallest (winner) rank.
// - In the scatter method, the "winner" rank and the 8 point global ids of each number of children) get rewritten.
using DataType = int;
ParentToChildCellToPointGlobalIdHandle(const Dune::CpGrid::Communication& comm,
const std::vector<std::tuple<int, std::vector<int>>>& parent_to_children,
const std::vector<std::vector<std::array<int,8>>>& level_cell_to_point,
std::vector<std::vector<DataType>>& level_winning_ranks,
std::vector<std::vector<DataType>>& level_point_global_ids)
: comm_(comm)
, parent_to_children_(parent_to_children)
, level_cell_to_point_(level_cell_to_point)
, level_winning_ranks_(level_winning_ranks)
, level_point_global_ids_(level_point_global_ids)
{}
bool fixedSize(std::size_t, std::size_t)
{
// Not every cell has children. When they have children, the amount might vary.
return false;
}
bool contains(std::size_t, std::size_t codim)
{
// Only communicate values attached to cells.
return codim == 0;
}
template <class T> // T = Entity<0>
std::size_t size(const T& element)
{
// Communicate variable size: 1 (rank) + (8* amount of child cells) from an interior parent cell from level zero grid.
// Skip values that are not interior, or have no children (in that case, 'invalid' level = -1)
const auto& [level, children] = parent_to_children_[element.index()];
// [Bug in dune-common] VariableSizeCommunicator will deadlock if a process attempts to send a message of size zero.
// This can happen if the size method returns zero for all entities that are shared with another process.
// Therefore, when skipping cells without children or for overlap cells, we set the size to 1.
if ( (element.partitionType() != Dune::InteriorEntity) || (level == -1))
return 1;
return 1 + ( 8*children.size()); // rank + 8 "winner" point global ids per child cell
}
// Gather global ids of child cells of a coarse interior parent cell
template <class B, class T> // T = Entity<0>
void gather(B& buffer, const T& element)
{
// Skip values that are not interior, or have no children (in that case, 'invalid level' = -1)
const auto& [level, children] = parent_to_children_[element.index()];
// [Bug in dune-common] VariableSizeCommunicator will deadlock if a process tries to send a message with size zero.
// To avoid this, for cells without children or for overlap cells, we set the size to 1 and write a single DataType
// value (e.g., '42').
if ( (element.partitionType() != Dune::InteriorEntity) || (level==-1)) {
buffer.write(42);
return;
}
// Store the children's corner global ids in the buffer when the element is interior and has children.
// Write the rank first, for example via the "corner 0" of cell_to_point_ of the first child:
// First child: children[0]
// First corner of first child: level_cell_to_point_[ level -1 ][children[0]] [0]
buffer.write( comm_.rank() );
for (const auto& child : children)
for (const auto& corner : level_cell_to_point_[level -1][child])
buffer.write(level_point_global_ids_[level-1][corner]);
}
// Scatter global ids of child cells of a coarse overlap parent cell
template <class B, class T> // T = Entity<0>
void scatter(B& buffer, const T& element, std::size_t size)
{
const auto& [level, children] = parent_to_children_[element.index()];
// Read all values to advance the pointer used by the buffer to the correct index.
// (Skip overlap-cells-without-children and interior-cells).
if ( ( (element.partitionType() == Dune::OverlapEntity) && (level==-1) ) || (element.partitionType() == Dune::InteriorEntity ) ) {
// Read all values to advance the pointer used by the buffer
// to the correct index
for (std::size_t received_int = 0; received_int < size; ++received_int) {
DataType tmp;
buffer.read(tmp);
}
}
else { // Overlap cell with children.
// Read and store the values in the correct location directly.
// The order of the children is the same on each process.
assert(children.size()>0);
assert(level>0);
// Read and store the values in the correct location directly.
DataType tmp_rank;
buffer.read(tmp_rank);
for (const auto& child : children) {
for (const auto& corner : level_cell_to_point_[level -1][child]) {
auto& min_rank = level_winning_ranks_[level-1][corner];
// Rewrite the rank (smaller rank wins)
if (tmp_rank < min_rank) {
min_rank = tmp_rank;
auto& target_entry = level_point_global_ids_[level-1][corner];
buffer.read(target_entry);
} else {
DataType rubbish;
buffer.read(rubbish);
}
}
}
}
}
private:
const Dune::CpGrid::Communication& comm_;
const std::vector<std::tuple<int, std::vector<int>>>& parent_to_children_;
const std::vector<std::vector<std::array<int,8>>>& level_cell_to_point_;
std::vector<std::vector<DataType>>& level_winning_ranks_;
std::vector<std::vector<DataType>>& level_point_global_ids_;
};
#endif // HAVE_MPI
} // namespace
#endif