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mesh_partition.cc
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/**
* @file mesh_partition.cc
*
* @author David Simon Kammer <david.kammer@epfl.ch>
* @author Nicolas Richart <nicolas.richart@epfl.ch>
*
* @date creation: Tue Aug 17 2010
* @date last modification: Fri Jul 24 2020
*
* @brief implementation of common part of all partitioner
*
*
* @section LICENSE
*
* Copyright (©) 2010-2021 EPFL (Ecole Polytechnique Fédérale de Lausanne)
* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
*
* Akantu is free software: you can 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 3 of the License, or (at your option) any
* later version.
*
* Akantu 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 Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Akantu. If not, see <http://www.gnu.org/licenses/>.
*
*/
/* -------------------------------------------------------------------------- */
#include "mesh_partition.hh"
#include "aka_iterators.hh"
#include "aka_types.hh"
#include "mesh_accessor.hh"
#include "mesh_iterators.hh"
#include "mesh_utils.hh"
/* -------------------------------------------------------------------------- */
#include <algorithm>
#include <numeric>
#include <unordered_map>
/* -------------------------------------------------------------------------- */
namespace akantu {
/* -------------------------------------------------------------------------- */
MeshPartition::MeshPartition(Mesh & mesh, UInt spatial_dimension, const ID & id)
: mesh(mesh), spatial_dimension(spatial_dimension),
partitions("partition", id), ghost_partitions("ghost_partition", id),
ghost_partitions_offset("ghost_partition_offset", id),
saved_connectivity("saved_connectivity", id) {
AKANTU_DEBUG_IN();
UInt nb_total_element = 0;
for (auto && type :
mesh.elementTypes(spatial_dimension, _not_ghost, _ek_not_defined)) {
linearized_offsets.emplace_back(type, nb_total_element);
nb_total_element += mesh.getConnectivity(type).size();
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
MeshPartition::~MeshPartition() = default;
/* -------------------------------------------------------------------------- */
UInt MeshPartition::linearized(const Element & element) {
auto it =
std::find_if(linearized_offsets.begin(), linearized_offsets.end(),
[&element](auto & a) { return a.first == element.type; });
AKANTU_DEBUG_ASSERT(it != linearized_offsets.end(),
"A bug might be crawling around this corner...");
return (it->second + element.element);
}
/* -------------------------------------------------------------------------- */
Element MeshPartition::unlinearized(UInt lin_element) {
ElementType type{_not_defined};
UInt offset{0};
for (auto & pair : linearized_offsets) {
if (lin_element < pair.second) {
continue;
}
std::tie(type, offset) = pair;
}
return Element{type, lin_element - offset, _not_ghost};
}
/* -------------------------------------------------------------------------- */
/**
* conversion in c++ of the METIS_MeshToDual (mesh.c) function wrote by George
* in Metis (University of Minnesota)
*/
void MeshPartition::buildDualGraph(
Array<Int> & dxadj, Array<Int> & dadjncy, Array<Int> & edge_loads,
const std::function<Int(const Element &, const Element &)> & edge_load_func,
Array<Int> & vertex_loads,
const std::function<Int(const Element &)> & vertex_load_func) {
CSR<Element> nodes_to_elements;
MeshUtils::buildNode2Elements(mesh, nodes_to_elements);
std::unordered_map<UInt, std::vector<UInt>> adjacent_elements;
// for each elements look for its connected elements
for_each_element(
mesh,
[&](auto && element) {
const auto & conn =
const_cast<const Mesh &>(mesh).getConnectivity(element);
std::map<Element, UInt> hits;
// count the number of nodes shared with a given element
for (auto && node : conn) {
for (auto && connected_element : nodes_to_elements.getRow(node)) {
++hits[connected_element];
}
}
// define a minumum number of nodes to share to be considered as a
// ajacent element
UInt magic_number{conn.size()};
for (auto n : arange(mesh.getNbFacetTypes(element.type))) {
magic_number = std::min(
mesh.getNbNodesPerElement(mesh.getFacetType(element.type, n)),
magic_number);
}
// check all neighbors to see which ones are "adjacent"
for (auto && data : hits) {
const auto & adjacent_element = data.first;
// not adjacent to miself
if (adjacent_element == element) {
continue;
}
// not enough shared nodes
if (data.second < magic_number) {
continue;
}
/// Patch in order to prevent neighboring cohesive elements
/// from detecting each other
#if defined(AKANTU_COHESIVE_ELEMENT)
auto element_kind = element.kind();
auto adjacent_element_kind = adjacent_element.kind();
if (element_kind == adjacent_element_kind &&
element_kind == _ek_cohesive) {
continue;
}
#endif
adjacent_elements[this->linearized(element)].push_back(
this->linearized(adjacent_element));
}
},
_spatial_dimension = mesh.getSpatialDimension(),
_element_kind = _ek_not_defined);
// prepare the arrays
auto nb_elements{adjacent_elements.size()};
dxadj.resize(nb_elements + 1);
vertex_loads.resize(nb_elements);
for (auto && data : adjacent_elements) {
const auto & element{data.first};
const auto & neighbors{data.second};
dxadj[element] = neighbors.size();
}
/// convert the dxadj array of sizes in a csr one of offsets
for (UInt i = 1; i < nb_elements; ++i) {
dxadj(i) += dxadj(i - 1);
}
for (UInt i = nb_elements; i > 0; --i) {
dxadj(i) = dxadj(i - 1);
}
dxadj(0) = 0;
dadjncy.resize(dxadj(nb_elements));
edge_loads.resize(dadjncy.size());
// fill the different arrays
for (auto && data : adjacent_elements) {
const auto & element{data.first};
const auto & neighbors{data.second};
auto unlinearized_element = unlinearized(element);
vertex_loads(element) = vertex_load_func(unlinearized_element);
auto pos = dxadj(element);
for (auto && neighbor : neighbors) {
dadjncy(pos) = neighbor;
edge_loads(pos) =
edge_load_func(unlinearized_element, unlinearized(neighbor));
++pos;
}
}
}
/* -------------------------------------------------------------------------- */
void MeshPartition::fillPartitionInformation(
const Mesh & mesh, const Int * linearized_partitions) {
AKANTU_DEBUG_IN();
CSR<Element> node_to_elem;
MeshUtils::buildNode2Elements(mesh, node_to_elem);
UInt linearized_el = 0;
for (const auto & type :
mesh.elementTypes(spatial_dimension, _not_ghost, _ek_not_defined)) {
UInt nb_element = mesh.getNbElement(type);
UInt nb_nodes_per_element = Mesh::getNbNodesPerElement(type);
auto & partition = partitions.alloc(nb_element, 1, type, _not_ghost);
auto & ghost_part_csr = ghost_partitions_csr(type, _not_ghost);
ghost_part_csr.resizeRows(nb_element);
auto & ghost_partition_offset =
ghost_partitions_offset.alloc(nb_element + 1, 1, type, _ghost);
auto & ghost_partition = ghost_partitions.alloc(0, 1, type, _ghost);
const auto & connectivity = mesh.getConnectivity(type, _not_ghost);
auto conn_it = connectivity.begin(connectivity.getNbComponent());
for (UInt el = 0; el < nb_element; ++el, ++linearized_el) {
UInt part = linearized_partitions[linearized_el];
partition(el) = part;
std::list<UInt> list_adj_part;
for (UInt n = 0; n < nb_nodes_per_element; ++n) {
auto conn = Vector<UInt>(*(conn_it + el));
UInt node = conn(n);
for (const auto & adj_element : node_to_elem.getRow(node)) {
UInt adj_el = linearized(adj_element);
UInt adj_part = linearized_partitions[adj_el];
if (part != adj_part) {
list_adj_part.push_back(adj_part);
}
}
}
list_adj_part.sort();
list_adj_part.unique();
for (auto & adj_part : list_adj_part) {
ghost_part_csr.getRows().push_back(adj_part);
ghost_part_csr.rowOffset(el)++;
ghost_partition.push_back(adj_part);
ghost_partition_offset(el)++;
}
}
ghost_part_csr.countToCSR();
/// convert the ghost_partitions_offset array in an offset array
auto & ghost_partitions_offset_ptr = ghost_partitions_offset(type, _ghost);
for (UInt i = 1; i < nb_element; ++i) {
ghost_partitions_offset_ptr(i) += ghost_partitions_offset_ptr(i - 1);
}
for (UInt i = nb_element; i > 0; --i) {
ghost_partitions_offset_ptr(i) = ghost_partitions_offset_ptr(i - 1);
}
ghost_partitions_offset_ptr(0) = 0;
}
// All Facets
for (Int sp = spatial_dimension - 1; sp >= 0; --sp) {
for (const auto & type :
mesh.elementTypes(sp, _not_ghost, _ek_not_defined)) {
UInt nb_element = mesh.getNbElement(type);
auto & partition = partitions.alloc(nb_element, 1, type, _not_ghost);
AKANTU_DEBUG_INFO("Allocating partitions for " << type);
auto & ghost_part_csr = ghost_partitions_csr(type, _not_ghost);
ghost_part_csr.resizeRows(nb_element);
auto & ghost_partition_offset =
ghost_partitions_offset.alloc(nb_element + 1, 1, type, _ghost);
auto & ghost_partition = ghost_partitions.alloc(0, 1, type, _ghost);
AKANTU_DEBUG_INFO("Allocating ghost_partitions for " << type);
const Array<std::vector<Element>> & elem_to_subelem =
mesh.getElementToSubelement(type, _not_ghost);
// Facet loop
for (UInt i(0); i < mesh.getNbElement(type, _not_ghost); ++i) {
const auto & adjacent_elems = elem_to_subelem(i);
if (adjacent_elems.empty()) {
partition(i) = 0;
continue;
}
Element min_elem{_max_element_type, std::numeric_limits<UInt>::max(),
*(ghost_type_t{}.end())};
UInt min_part(std::numeric_limits<UInt>::max());
std::set<UInt> adjacent_parts;
for (auto adj_elem : adjacent_elems) {
if (adj_elem == ElementNull) { // case of boundary elements
continue;
}
auto adjacent_elem_part = partitions(adj_elem);
if (adjacent_elem_part < min_part) {
min_part = adjacent_elem_part;
min_elem = adj_elem;
}
adjacent_parts.insert(adjacent_elem_part);
}
partition(i) = min_part;
auto git = ghost_partitions_csr(min_elem.type, _not_ghost)
.begin(min_elem.element);
auto gend = ghost_partitions_csr(min_elem.type, _not_ghost)
.end(min_elem.element);
for (; git != gend; ++git) {
adjacent_parts.insert(*git);
}
adjacent_parts.erase(min_part);
for (const auto & part : adjacent_parts) {
ghost_part_csr.getRows().push_back(part);
ghost_part_csr.rowOffset(i)++;
ghost_partition.push_back(part);
}
ghost_partition_offset(i + 1) =
ghost_partition_offset(i + 1) + adjacent_elems.size();
}
ghost_part_csr.countToCSR();
}
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void MeshPartition::tweakConnectivity() {
AKANTU_DEBUG_IN();
MeshAccessor mesh_accessor(const_cast<Mesh &>(mesh));
for (auto && type :
mesh.elementTypes(spatial_dimension, _not_ghost, _ek_not_defined)) {
auto & connectivity = mesh_accessor.getConnectivity(type, _not_ghost);
auto & saved_conn = saved_connectivity.alloc(
connectivity.size(), connectivity.getNbComponent(), type, _not_ghost);
saved_conn.copy(connectivity);
for (auto && conn :
make_view(connectivity, connectivity.getNbComponent())) {
for (auto && node : conn) {
if (mesh.isPeriodicSlave(node)) {
node = mesh.getPeriodicMaster(node);
}
}
}
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void MeshPartition::restoreConnectivity() {
AKANTU_DEBUG_IN();
MeshAccessor mesh_accessor(const_cast<Mesh &>(mesh));
for (auto && type : saved_connectivity.elementTypes(
spatial_dimension, _not_ghost, _ek_not_defined)) {
auto & conn = mesh_accessor.getConnectivity(type, _not_ghost);
auto & saved_conn = saved_connectivity(type, _not_ghost);
conn.copy(saved_conn);
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
bool MeshPartition::hasPartitions(ElementType type, GhostType ghost_type) {
return partitions.exists(type, ghost_type);
}
/* -------------------------------------------------------------------------- */
void MeshPartition::printself(std::ostream & stream, int indent) const {
std::string space(indent, AKANTU_INDENT);
stream << space << "MeshPartition ["
<< "\n";
stream << space << " + id : " << id << "\n";
stream << space << " + nb partitions: " << nb_partitions << "\n";
stream << space << " + partitions [ "
<< "\n";
partitions.printself(stream, indent + 2);
stream << space << " ]"
<< "\n";
stream << space << "]"
<< "\n";
}
/* -------------------------------------------------------------------------- */
} // namespace akantu

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