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// Copyright (C) 2021 Jorgen S. Dokken
//
// This file is part of DOLFINX_MPC
//
// SPDX-License-Identifier: MIT
#pragma once
#include <dolfinx/fem/FunctionSpace.h>
#include <dolfinx/graph/AdjacencyList.h>
namespace dolfinx_mpc
{
/// Create a map from cell to a set of dofs
/// @param[in] The degrees of freedom (local to process)
/// @tparam The floating type of the mesh
/// @returns The map from cell index (local to process) to dofs (local to
/// process) in the cell
template <std::floating_point U>
std::shared_ptr<const dolfinx::graph::AdjacencyList<std::int32_t>>
create_cell_to_dofs_map(const dolfinx::fem::FunctionSpace<U>& V,
std::span<const std::int32_t> dofs)
{
const auto& mesh = *(V.mesh());
const dolfinx::fem::DofMap& dofmap = *(V.dofmap());
const int tdim = mesh.topology()->dim();
const int num_cells = mesh.topology()->index_map(tdim)->size_local();
const std::int32_t local_size
= dofmap.index_map->size_local() + dofmap.index_map->num_ghosts();
const std::int32_t block_size = dofmap.index_map_bs();
// Create dof -> cells map where only slave dofs have entries
std::shared_ptr<const dolfinx::graph::AdjacencyList<std::int32_t>> cell_map;
{
std::vector<std::int32_t> num_slave_cells(local_size * block_size, 0);
std::vector<std::int32_t> in_num_cells(local_size * block_size, 0);
// Loop through all cells and count number of cells a dof occurs in
for (std::int32_t i = 0; i < num_cells; i++)
for (auto block : dofmap.cell_dofs(i))
for (std::int32_t j = 0; j < block_size; j++)
in_num_cells[block * block_size + j]++;
// Count only number of slave cells for dofs
for (auto dof : dofs)
num_slave_cells[dof] = in_num_cells[dof];
std::vector<std::int32_t> insert_position(local_size * block_size, 0);
std::vector<std::int32_t> cell_offsets(local_size * block_size + 1);
cell_offsets[0] = 0;
std::inclusive_scan(num_slave_cells.begin(), num_slave_cells.end(),
cell_offsets.begin() + 1);
std::vector<std::int32_t> cell_data(cell_offsets.back());
// Accumulate those cells whose contains a slave dof
for (std::int32_t i = 0; i < num_cells; i++)
{
for (auto block : dofmap.cell_dofs(i))
{
for (std::int32_t j = 0; j < block_size; j++)
{
if (const std::int32_t dof = block * block_size + j;
num_slave_cells[dof] > 0)
{
cell_data[cell_offsets[dof] + insert_position[dof]++] = i;
}
}
}
}
cell_map
= std::make_shared<const dolfinx::graph::AdjacencyList<std::int32_t>>(
cell_data, cell_offsets);
}
// Create inverse map (cells -> slave dofs)
std::vector<std::int32_t> num_slaves(num_cells, 0);
for (std::int32_t i = 0; i < cell_map->num_nodes(); i++)
for (auto cell : cell_map->links(i))
num_slaves[cell]++;
std::vector<std::int32_t> insert_position(num_cells, 0);
std::vector<std::int32_t> dof_offsets(num_cells + 1);
dof_offsets[0] = 0;
std::inclusive_scan(num_slaves.begin(), num_slaves.end(),
dof_offsets.begin() + 1);
std::vector<std::int32_t> dof_data(dof_offsets.back());
for (std::int32_t i = 0; i < cell_map->num_nodes(); i++)
for (auto cell : cell_map->links(i))
dof_data[dof_offsets[cell] + insert_position[cell]++] = i;
return std::make_shared<const dolfinx::graph::AdjacencyList<std::int32_t>>(
dof_data, dof_offsets);
}
/// Given a list of global degrees of freedom, map them to their local index
/// @param[in] V The original function space
/// @param[in] global_dofs The list of dofs (global index)
/// @tparam The floating type of the mesh
/// @returns List of local dofs
template <std::floating_point U>
std::vector<std::int32_t>
map_dofs_global_to_local(const dolfinx::fem::FunctionSpace<U>& V,
const std::vector<std::int64_t>& global_dofs)
{
const std::size_t num_dofs = global_dofs.size();
const std::int32_t& block_size = V.dofmap()->index_map_bs();
const std::shared_ptr<const dolfinx::common::IndexMap> imap
= V.dofmap()->index_map;
std::vector<std::int64_t> global_blocks;
global_blocks.reserve(num_dofs);
std::vector<std::int32_t> remainders;
remainders.reserve(num_dofs);
std::ranges::for_each(
global_dofs,
[block_size, &global_blocks, &remainders](const auto slave)
{
global_blocks.push_back(slave / block_size);
remainders.push_back(slave % block_size);
});
// Compute the new local index of the master blocks
std::vector<std::int32_t> local_blocks(num_dofs);
imap->global_to_local(global_blocks, local_blocks);
// Go from blocks to actual local dof
for (std::size_t i = 0; i < local_blocks.size(); i++)
local_blocks[i] = local_blocks[i] * block_size + remainders[i];
return local_blocks;
}
/// Create an function space with an extended index map, where all input dofs
/// (global index) is added to the local index map as ghosts.
/// @param[in] V The original function space
/// @param[in] global_dofs The list of master dofs (global index)
/// @param[in] owners The owners of the master degrees of freedom
/// @tparam The floating type of the mesh
template <std::floating_point U>
dolfinx::fem::FunctionSpace<U>
create_extended_functionspace(const dolfinx::fem::FunctionSpace<U>& V,
const std::vector<std::int64_t>& global_dofs,
const std::vector<std::int32_t>& owners)
{
dolfinx::common::Timer timer(
"~MPC: Create new index map with additional ghosts");
MPI_Comm comm = V.mesh()->comm();
const dolfinx::fem::DofMap& old_dofmap = *(V.dofmap());
std::shared_ptr<const dolfinx::common::IndexMap> old_index_map
= old_dofmap.index_map;
const std::int32_t& block_size = V.dofmap()->index_map_bs();
// Compute local master block index.
const std::size_t num_dofs = global_dofs.size();
std::vector<std::int64_t> global_blocks(num_dofs);
std::vector<std::int32_t> local_blocks(num_dofs);
std::ranges::transform(global_dofs, global_blocks.begin(),
[block_size](const auto dof)
{ return dof / block_size; });
int mpi_size = -1;
MPI_Comm_size(comm, &mpi_size);
std::shared_ptr<const dolfinx::common::IndexMap> new_index_map;
if (mpi_size == 1)
{
new_index_map = old_index_map;
}
else
{
// Map global master blocks to local blocks
V.dofmap()->index_map->global_to_local(global_blocks, local_blocks);
// Check which local masters that are not on the process already
std::vector<std::int64_t> additional_ghosts;
additional_ghosts.reserve(num_dofs);
std::vector<std::int32_t> additional_owners;
additional_owners.reserve(num_dofs);
for (std::size_t i = 0; i < num_dofs; i++)
{
// Check if master block already has a local index and
// if has has already been ghosted, which is the case
// when we have multiple masters from the same block
if ((local_blocks[i] == -1)
and (std::ranges::find(additional_ghosts, global_blocks[i])
== additional_ghosts.end()))
{
additional_ghosts.push_back(global_blocks[i]);
additional_owners.push_back(owners[i]);
}
}
// Append new ghosts (and corresponding rank) at the end of the old set of
// ghosts originating from the old index map
std::span<const int> ghost_owners = old_index_map->owners();
std::span<const std::int64_t> ghosts = old_index_map->ghosts();
const std::int32_t num_ghosts = ghosts.size();
assert(ghost_owners.size() == ghosts.size());
std::vector<std::int64_t> all_ghosts(num_ghosts + additional_ghosts.size());
std::ranges::copy(ghosts, all_ghosts.begin());
std::ranges::copy(additional_ghosts, all_ghosts.begin() + num_ghosts);
std::vector<int> all_owners(all_ghosts.size());
std::ranges::copy(ghost_owners, all_owners.begin());
std::ranges::copy(additional_owners, all_owners.begin() + num_ghosts);
// Create new indexmap with ghosts for master blocks added
new_index_map = std::make_shared<dolfinx::common::IndexMap>(
comm, old_index_map->size_local(), all_ghosts, all_owners);
}
// Extract information from the old dofmap to create a new one
MDSPAN_IMPL_STANDARD_NAMESPACE::mdspan<
const std::int32_t,
MDSPAN_IMPL_STANDARD_NAMESPACE::dextents<std::size_t, 2>>
dofmap_adj = old_dofmap.map();
// Copy dofmap
std::vector<std::int32_t> flattened_dofmap;
flattened_dofmap.reserve(dofmap_adj.extent(0) * dofmap_adj.extent(1));
for (std::size_t i = 0; i < dofmap_adj.extent(0); ++i)
for (std::size_t j = 0; j < dofmap_adj.extent(1); ++j)
flattened_dofmap.push_back(dofmap_adj(i, j));
auto element = V.element();
// Create the new dofmap based on the extended index map
auto new_dofmap = std::make_shared<const dolfinx::fem::DofMap>(
old_dofmap.element_dof_layout(), new_index_map, old_dofmap.bs(),
std::move(flattened_dofmap), old_dofmap.bs());
return dolfinx::fem::FunctionSpace(
V.mesh(), element, new_dofmap,
dolfinx::fem::compute_value_shape(element, V.mesh()->topology()->dim(),
V.mesh()->geometry().dim()));
}
} // namespace dolfinx_mpc
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