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// Copyright (C) 2019 Igor A. Baratta
//
// This file is part of DOLFINx (https://www.fenicsproject.org)
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
// Unit tests for Distributed Meshes
#include <algorithm>
#include <basix/finite-element.h>
#include <catch2/catch_test_macros.hpp>
#include <dolfinx.h>
#include <dolfinx/common/MPI.h>
#include <dolfinx/graph/partitioners.h>
#include <dolfinx/io/XDMFFile.h>
#include <dolfinx/mesh/cell_types.h>
#include <dolfinx/mesh/graphbuild.h>
#include <memory>
using namespace dolfinx;
namespace
{
constexpr int N = 8;
/// @brief Create a mesh and save to the file 'mesh.xdmf'
[[maybe_unused]] void create_mesh_file(MPI_Comm comm)
{
// Create mesh using all processes and save xdmf
auto part = mesh::create_cell_partitioner(mesh::GhostMode::shared_facet);
auto mesh = std::make_shared<mesh::Mesh<double>>(
mesh::create_rectangle(comm, {{{0.0, 0.0}, {1.0, 1.0}}}, {N, N},
mesh::CellType::triangle, part));
// Save mesh in XDMF format
io::XDMFFile file(MPI_COMM_SELF, "mesh.xdmf", "w");
file.write_mesh(*mesh);
}
[[maybe_unused]] void test_create_box(const mesh::CellPartitionFunction& part)
{
MPI_Comm comm;
MPI_Comm_dup(MPI_COMM_WORLD, &comm);
// Create sub-communicator on even ranks
const int mpi_rank = dolfinx::MPI::rank(comm);
int color = mpi_rank % 2 ? MPI_UNDEFINED : 1;
MPI_Comm subcomm = MPI_COMM_NULL;
MPI_Comm_split(comm, color, mpi_rank, &subcomm);
// Create mesh on comm and distribute to all ranks in comm
mesh::Mesh<double> mesh0
= mesh::create_box(comm, comm, {{{0.0, 0.0, 0.0}, {1.0, 1.0, 1.0}}},
{12, 12, 12}, mesh::CellType::hexahedron, part);
int tdim = mesh0.topology()->dim();
mesh0.topology()->create_entities(tdim - 1);
// Create mesh on even ranks (subcomm) and distribute to all ranks in
// comm
mesh::Mesh<double> mesh1
= mesh::create_box(comm, subcomm, {{{0.0, 0.0, 0.0}, {1.0, 1.0, 1.0}}},
{12, 12, 12}, mesh::CellType::hexahedron, part);
int tdim1 = mesh1.topology()->dim();
mesh1.topology()->create_entities(tdim1 - 1);
// Check that mesh communicators are the same
int equal;
MPI_Comm_compare(mesh0.comm(), mesh1.comm(), &equal);
CHECK(equal != MPI_UNEQUAL);
// Check global sizes for topology and geometry
auto t0 = mesh0.topology();
auto t1 = mesh1.topology();
CHECK(t0->index_map(tdim)->size_global()
== t1->index_map(tdim)->size_global());
CHECK(t0->index_map(tdim - 1)->size_global()
== t1->index_map(tdim - 1)->size_global());
CHECK(t0->index_map(0)->size_global() == t1->index_map(0)->size_global());
CHECK(mesh0.geometry().index_map()->size_global()
== mesh1.geometry().index_map()->size_global());
if (subcomm != MPI_COMM_NULL)
MPI_Comm_free(&subcomm);
MPI_Comm_free(&comm);
}
void test_distributed_mesh(const mesh::CellPartitionFunction& partitioner)
{
using T = double;
MPI_Comm comm = MPI_COMM_WORLD;
const int mpi_size = dolfinx::MPI::size(comm);
// -- Create a communicator with subset of the original group of
// processes
// Get group of processes on comm
MPI_Group comm_group;
int ierr = MPI_Comm_group(comm, &comm_group);
if (ierr != MPI_SUCCESS)
throw std::runtime_error("MPI_Comm_group failed");
// Create a group of processes (lower 'half' of processes by rank)
std::vector<int> ranks(std::max(mpi_size / 2, 1));
std::iota(ranks.begin(), ranks.end(), 0);
MPI_Group new_group;
ierr = MPI_Group_incl(comm_group, ranks.size(), ranks.data(), &new_group);
if (ierr != MPI_SUCCESS)
throw std::runtime_error("MPI_Group_incl failed");
// Create new communicator
MPI_Comm subset_comm = MPI_COMM_NULL;
ierr = MPI_Comm_create_group(MPI_COMM_WORLD, new_group, 0, &subset_comm);
if (ierr != MPI_SUCCESS)
throw std::runtime_error("MPI_Comm_create_group failed");
// Create coordinate map
auto e = std::make_shared<basix::FiniteElement<T>>(basix::create_element<T>(
basix::element::family::P, basix::cell::type::triangle, 1,
basix::element::lagrange_variant::unset,
basix::element::dpc_variant::unset, false));
fem::CoordinateElement<T> cmap(e);
// Read mesh data from file on sub-communicator
std::vector<T> x;
std::array<std::size_t, 2> xshape{0, 2};
std::array<std::size_t, 2> cshape{0, 3};
std::vector<std::int64_t> cells;
if (subset_comm != MPI_COMM_NULL)
{
io::XDMFFile infile(subset_comm, "mesh.xdmf", "r");
auto [_cells, _cshape] = infile.read_topology_data("mesh");
auto [_x, _xshape] = infile.read_geometry_data("mesh");
CHECK(_cshape[1] == cshape[1]);
x = std::move(std::get<std::vector<T>>(_x));
cells = std::move(_cells);
}
CHECK(xshape[1] == 2);
// Build mesh
mesh::Mesh mesh = mesh::create_mesh(comm, subset_comm, cells, cmap, comm, x,
xshape, partitioner);
auto t = mesh.topology();
int tdim = t->dim();
CHECK(t->index_map(tdim)->size_global() == 2 * N * N);
CHECK(t->index_map(tdim)->size_local() > 0);
CHECK(t->index_map(0)->size_global() == (N + 1) * (N + 1));
CHECK(t->index_map(0)->size_local() > 0);
CHECK((int)mesh.geometry().x().size() / 3
== t->index_map(0)->size_local() + t->index_map(0)->num_ghosts());
MPI_Group_free(&comm_group);
MPI_Group_free(&new_group);
if (subset_comm != MPI_COMM_NULL)
MPI_Comm_free(&subset_comm);
}
} // namespace
/// Create a mesh on even ranks and distribute to all ranks in mpi_comm
TEST_CASE("Create box", "[create_box]")
{
#ifdef HAS_PTSCOTCH
CHECK_NOTHROW(test_create_box(mesh::create_cell_partitioner(
mesh::GhostMode::none, graph::scotch::partitioner())));
#endif
#ifdef HAS_PARMETIS
CHECK_NOTHROW(test_create_box(mesh::create_cell_partitioner(
mesh::GhostMode::none, graph::parmetis::partitioner())));
#endif
// #ifdef HAS_KAHIP
// CHECK_NOTHROW(test_create_box(mesh::create_cell_partitioner(
// mesh::GhostMode::none, graph::kahip::partitioner(1, 1, 0.03,
// false))));
// #endif
}
TEST_CASE("Distributed Mesh", "[distributed_mesh]")
{
MPI_Barrier(MPI_COMM_WORLD);
if (dolfinx::MPI::rank(MPI_COMM_WORLD) == 0)
create_mesh_file(MPI_COMM_SELF);
MPI_Barrier(MPI_COMM_WORLD);
#ifdef HAS_PTSCOTCH
CHECK_NOTHROW(test_distributed_mesh(mesh::create_cell_partitioner(
mesh::GhostMode::none, graph::scotch::partitioner())));
#endif
#ifdef HAS_PARMETIS
CHECK_NOTHROW(test_distributed_mesh(mesh::create_cell_partitioner(
mesh::GhostMode::none, graph::parmetis::partitioner())));
#endif
#ifdef HAS_KAHIP
CHECK_NOTHROW(test_distributed_mesh(mesh::create_cell_partitioner(
mesh::GhostMode::none, graph::kahip::partitioner(1, 1, 0.03, false))));
#endif
}
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