CellSystem.cpp

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/*
 * Copyright (C) 2022 The ESPResSo project
 *
 * This file is part of ESPResSo.
 *
 * ESPResSo 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.
 *
 * ESPResSo 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "CellSystem.hpp"
 
#include "script_interface/ScriptInterface.hpp"
#include "script_interface/particle_data/ParticleHandle.hpp"
#include "script_interface/particle_data/ParticleSlice.hpp"
 
#include "core/BoxGeometry.hpp"
#include "core/bonded_interactions/bonded_interaction_data.hpp"
#include "core/cell_system/CellStructure.hpp"
#include "core/cell_system/HybridDecomposition.hpp"
#include "core/cell_system/RegularDecomposition.hpp"
#include "core/cells.hpp"
#include "core/communication.hpp"
#include "core/nonbonded_interactions/nonbonded_interaction_data.hpp"
#include "core/particle_node.hpp"
#include "core/system/System.hpp"
#include "core/tuning.hpp"
 
#include <utils/Vector.hpp>
#include <utils/mpi/gather_buffer.hpp>
 
#include <boost/mpi/collectives/gather.hpp>
#include <boost/variant.hpp>
 
#include <algorithm>
#include <cassert>
#include <iterator>
#include <optional>
#include <set>
#include <sstream>
#include <stdexcept>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
 
static int coord(std::string const &s) {
  if (s == "x")
    return 0;
  if (s == "y")
    return 1;
  if (s == "z")
    return 2;
  throw std::invalid_argument("Invalid Cartesian coordinate: '" + s + "'");
}
 
static std::string coord_letter(int c) {
  if (c == 0)
    return "x";
  if (c == 1)
    return "y";
  assert(c == 2);
  return "z";
}
 
namespace ScriptInterface {
namespace CellSystem {
 
CellSystem::CellSystem() {
  add_parameters({
      {"use_verlet_lists",
       [this](Variant const &v) {
         get_cell_structure().use_verlet_list = get_value<bool>(v);
       },
       [this]() { return get_cell_structure().use_verlet_list; }},
      {"node_grid",
       [this](Variant const &v) {
         context()->parallel_try_catch([this, &v]() {
           auto const error_msg = std::string("Parameter 'node_grid'");
           auto const old_node_grid = ::communicator.node_grid;
           auto const new_node_grid = get_value<Utils::Vector3i>(v);
           auto const n_nodes_old = Utils::product(old_node_grid);
           auto const n_nodes_new = Utils::product(new_node_grid);
           if (n_nodes_new != n_nodes_old) {
             std::stringstream reason;
             reason << ": MPI world size " << n_nodes_old << " incompatible "
                    << "with new node grid [" << new_node_grid << "]";
             throw std::invalid_argument(error_msg + reason.str());
           }
           try {
             ::communicator.set_node_grid(new_node_grid);
             get_system().on_node_grid_change();
           } catch (...) {
             ::communicator.set_node_grid(old_node_grid);
             get_system().on_node_grid_change();
             throw;
           }
         });
       },
       []() { return ::communicator.node_grid; }},
      {"skin",
       [this](Variant const &v) {
         auto const new_skin = get_value<double>(v);
         if (new_skin < 0.) {
           if (context()->is_head_node()) {
             throw std::domain_error("Parameter 'skin' must be >= 0");
           }
           throw Exception("");
         }
         get_cell_structure().set_verlet_skin(new_skin);
       },
       [this]() { return get_cell_structure().get_verlet_skin(); }},
      {"decomposition_type", AutoParameter::read_only,
       [this]() {
         return cs_type_to_name.at(get_cell_structure().decomposition_type());
       }},
      {"n_square_types", AutoParameter::read_only,
       [this]() {
         if (get_cell_structure().decomposition_type() !=
             CellStructureType::HYBRID) {
           return Variant{none};
         }
         auto const hd = get_hybrid_decomposition();
         auto const ns_types = hd.get_n_square_types();
         return Variant{std::vector<int>(ns_types.begin(), ns_types.end())};
       }},
      {"fully_connected_boundary", AutoParameter::read_only,
       [this]() {
         if (get_cell_structure().decomposition_type() !=
             CellStructureType::REGULAR) {
           return Variant{none};
         }
         auto const rd = get_regular_decomposition();
         auto const fcb = rd.fully_connected_boundary();
         if (not fcb)
           return Variant{none};
         return Variant{std::unordered_map<std::string, Variant>{
             {{"boundary", Variant{coord_letter((*fcb).first)}},
              {"direction", Variant{coord_letter((*fcb).second)}}}}};
       }},
      {"cutoff_regular", AutoParameter::read_only,
       [this]() {
         if (get_cell_structure().decomposition_type() !=
             CellStructureType::HYBRID) {
           return Variant{none};
         }
         auto const hd = get_hybrid_decomposition();
         return Variant{hd.get_cutoff_regular()};
       }},
      {"max_cut_nonbonded", AutoParameter::read_only,
       [this]() { return get_system().nonbonded_ias->maximal_cutoff(); }},
      {"max_cut_bonded", AutoParameter::read_only,
       [this]() { return get_system().bonded_ias->maximal_cutoff(); }},
      {"interaction_range", AutoParameter::read_only,
       [this]() { return get_system().get_interaction_range(); }},
  });
}
 
Variant CellSystem::do_call_method(std::string const &name,
                                   VariantMap const &params) {
  if (name == "initialize") {
    auto const cs_name = get_value<std::string>(params, "name");
    auto const cs_type = cs_name_to_type.at(cs_name);
    initialize(cs_type, params);
    return {};
  }
  if (name == "resort") {
    auto const global_flag = get_value_or<bool>(params, "global_flag", true);
    return mpi_resort_particles(global_flag);
  }
  if (name == "get_state") {
    auto state = get_parameters();
    auto const cs_type = get_cell_structure().decomposition_type();
    if (cs_type == CellStructureType::REGULAR) {
      auto const rd = get_regular_decomposition();
      state["cell_grid"] = Variant{rd.cell_grid};
      state["cell_size"] = Variant{rd.cell_size};
    } else if (cs_type == CellStructureType::HYBRID) {
      auto const hd = get_hybrid_decomposition();
      state["cell_grid"] = Variant{hd.get_cell_grid()};
      state["cell_size"] = Variant{hd.get_cell_size()};
      mpi_resort_particles(true); // needed to get correct particle counts
      state["parts_per_decomposition"] =
          Variant{std::unordered_map<std::string, Variant>{
              {"regular", hd.count_particles_in_regular()},
              {"n_square", hd.count_particles_in_n_square()}}};
    }
    state["verlet_reuse"] = get_cell_structure().get_verlet_reuse();
    state["n_nodes"] = context()->get_comm().size();
    return state;
  }
  if (name == "get_pairs") {
    std::vector<Variant> out;
    context()->parallel_try_catch([this, &params, &out]() {
      auto &system = get_system();
      system.on_observable_calc();
      std::vector<std::pair<int, int>> pair_list;
      auto const distance = get_value<double>(params, "distance");
      if (boost::get<std::string>(&params.at("types")) != nullptr) {
        auto const key = get_value<std::string>(params, "types");
        if (key != "all") {
          throw std::invalid_argument("Unknown argument types='" + key + "'");
        }
        pair_list = get_pairs(system, distance);
      } else {
        auto const types = get_value<std::vector<int>>(params, "types");
        pair_list = get_pairs_of_types(system, distance, types);
      }
      Utils::Mpi::gather_buffer(pair_list, context()->get_comm());
      std::ranges::transform(pair_list, std::back_inserter(out),
                             [](auto const &pair) {
                               return std::vector<int>{pair.first, pair.second};
                             });
    });
    return out;
  }
  if (name == "get_neighbors") {
    std::vector<std::vector<int>> neighbors_global;
    context()->parallel_try_catch([this, &neighbors_global, &params]() {
      auto &system = get_system();
      system.on_observable_calc();
      auto const dist = get_value<double>(params, "distance");
      auto const pid = get_value<int>(params, "pid");
      auto const ret = get_short_range_neighbors(system, pid, dist);
      std::vector<int> neighbors_local;
      if (ret) {
        neighbors_local = *ret;
      }
      boost::mpi::gather(context()->get_comm(), neighbors_local,
                         neighbors_global, 0);
    });
    std::vector<int> neighbors;
    for (auto const &neighbors_local : neighbors_global) {
      if (not neighbors_local.empty()) {
        neighbors = neighbors_local;
        break;
      }
    }
    return neighbors;
  }
  if (name == "non_bonded_loop_trace") {
    auto &system = get_system();
    system.on_observable_calc();
    std::vector<Variant> out;
    auto pair_list =
        non_bonded_loop_trace(system, context()->get_comm().rank());
    Utils::Mpi::gather_buffer(pair_list, context()->get_comm());
    std::ranges::transform(
        pair_list, std::back_inserter(out), [](auto const &pair) {
          return std::vector<Variant>{pair.id1,  pair.id2,   pair.pos1,
                                      pair.pos2, pair.vec21, pair.node};
        });
    return out;
  }
  if (name == "tune_skin") {
    auto &system = get_system();
    system.tune_verlet_skin(
        get_value<double>(params, "min_skin"),
        get_value<double>(params, "max_skin"), get_value<double>(params, "tol"),
        get_value<int>(params, "int_steps"),
        get_value_or<bool>(params, "adjust_max_skin", false));
    return get_cell_structure().get_verlet_skin();
  }
  if (name == "get_max_range") {
    return get_cell_structure().max_range();
  }
  return {};
}
 
std::vector<int> CellSystem::mpi_resort_particles(bool global_flag) const {
  auto &cell_structure = get_cell_structure();
  cell_structure.resort_particles(global_flag);
  clear_particle_node();
  auto const size = static_cast<int>(cell_structure.local_particles().size());
  std::vector<int> n_part_per_node;
  boost::mpi::gather(context()->get_comm(), size, n_part_per_node, 0);
  return n_part_per_node;
}
 
void CellSystem::initialize(CellStructureType const &cs_type,
                            VariantMap const &params) {
  auto const verlet = get_value_or<bool>(params, "use_verlet_lists", true);
  auto &system = get_system();
  m_cell_structure->use_verlet_list = verlet;
  if (cs_type == CellStructureType::HYBRID) {
    auto const cutoff_regular = get_value<double>(params, "cutoff_regular");
    auto const ns_types =
        get_value_or<std::vector<int>>(params, "n_square_types", {});
    auto n_square_types = std::set<int>{ns_types.begin(), ns_types.end()};
    m_cell_structure->set_hybrid_decomposition(cutoff_regular, n_square_types);
  } else if (cs_type == CellStructureType::REGULAR) {
    std::optional<std::pair<int, int>> fcb_pair = std::nullopt;
    if (params.contains("fully_connected_boundary") and
        not is_none(params.at("fully_connected_boundary"))) {
      auto const variant =
          get_value<VariantMap>(params, "fully_connected_boundary");
      context()->parallel_try_catch([&fcb_pair, &variant]() {
        fcb_pair = {{coord(boost::get<std::string>(variant.at("boundary"))),
                     coord(boost::get<std::string>(variant.at("direction")))}};
      });
    }
    context()->parallel_try_catch([this, &fcb_pair]() {
      m_cell_structure->set_regular_decomposition(
          get_system().get_interaction_range(), fcb_pair);
    });
  } else {
    system.set_cell_structure_topology(cs_type);
  }
}
 
void CellSystem::configure(Particles::ParticleHandle &particle) {
  particle.attach(m_system);
}
 
void CellSystem::configure(Particles::ParticleSlice &slice) {
  slice.attach(m_system);
}
 
} // namespace CellSystem
} // namespace ScriptInterface