FaceUniqueIdBuilder.cc

// -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
//-----------------------------------------------------------------------------
// Copyright 2000-2026 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
// See the top-level COPYRIGHT file for details.
// SPDX-License-Identifier: Apache-2.0
//-----------------------------------------------------------------------------
/*---------------------------------------------------------------------------*/
/* FaceUniqueIdBuilder.cc                                      (C) 2000-2025 */
/*                                                                           */
/* Construction of unique face identifiers.                                  */
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
#include "arcane/utils/PlatformUtils.h"
#include "arcane/utils/ScopedPtr.h"
#include "arcane/utils/ITraceMng.h"
#include "arcane/utils/OStringStream.h"
#include "arcane/utils/CheckedConvert.h"
 
#include "arcane/core/IMeshUniqueIdMng.h"
#include "arcane/core/IParallelExchanger.h"
#include "arcane/core/IParallelMng.h"
#include "arcane/core/ISerializeMessage.h"
#include "arcane/core/ISerializer.h"
#include "arcane/core/ParallelMngUtils.h"
 
#include "arcane/mesh/DynamicMesh.h"
#include "arcane/mesh/OneMeshItemAdder.h"
#include "arcane/mesh/GhostLayerBuilder.h"
#include "arcane/mesh/FaceUniqueIdBuilder.h"
#include "arcane/mesh/ItemTools.h"
#include "arcane/mesh/ItemsOwnerBuilder.h"
 
#include <unordered_set>
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
namespace Arcane::mesh
{
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
extern "C++" void
_computeFaceUniqueIdVersion3(DynamicMesh* mesh);
extern "C++" void
_computeFaceUniqueIdVersion5(DynamicMesh* mesh);
extern "C++" void
arcaneComputeCartesianFaceUniqueId(DynamicMesh* mesh);
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
FaceUniqueIdBuilder::
FaceUniqueIdBuilder(DynamicMeshIncrementalBuilder* mesh_builder)
: TraceAccessor(mesh_builder->mesh()->traceMng())
, m_mesh(mesh_builder->mesh())
, m_mesh_builder(mesh_builder)
{
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
void FaceUniqueIdBuilder::
computeFacesUniqueIds()
{
  IParallelMng* pm = m_mesh->parallelMng();
  Real begin_time = platform::getRealTime();
  Integer face_version = m_mesh->meshUniqueIdMng()->faceBuilderVersion();
  bool is_parallel = pm->isParallel();
  info() << "Using version=" << face_version << " to compute faces unique ids"
         << " mesh=" << m_mesh->name() << " is_parallel=" << is_parallel;
 
  if (face_version > 5 || face_version < 0)
    ARCANE_FATAL("Invalid value '{0}' for compute face unique ids versions: v>=0 && v<=6", face_version);
 
  if (face_version == 5)
    _computeFaceUniqueIdVersion5(m_mesh);
  else if (face_version == 4)
    arcaneComputeCartesianFaceUniqueId(m_mesh);
  else if (face_version == 3)
    _computeFaceUniqueIdVersion3(m_mesh);
  else if (face_version == 0) {
    info() << "No face renumbering";
  }
  else {
    // Version 1 or 2
    if (is_parallel) {
      if (face_version == 2) {
        //NOT YET BY DEFAULT
        info() << "Use new mesh init in FaceUniqueIdBuilder";
        _computeFacesUniqueIdsParallelV2();
      }
      else {
        // Default version.
        _computeFacesUniqueIdsParallelV1();
      }
    }
    else {
      _computeFacesUniqueIdsSequential();
    }
  }
 
  Real end_time = platform::getRealTime();
  Real diff = (Real)(end_time - begin_time);
  info() << "TIME to compute face unique ids=" << diff;
 
  if (arcaneIsCheck())
    _checkNoDuplicate();
 
  ItemInternalMap& faces_map = m_mesh->facesMap();
 
  // We must re-index #m_faces_map because the uniqueId() of the
  // faces have been modified
  if (face_version != 0)
    m_mesh->faceFamily()->notifyItemsUniqueIdChanged();
 
  bool is_verbose = m_mesh_builder->isVerbose();
  if (is_verbose) {
    info() << "NEW FACES_MAP after re-indexing";
    faces_map.eachItem([&](Item face) {
      info() << "Face uid=" << face.uniqueId() << " lid=" << face.localId();
    });
  }
  // With version 0 or 5, the owners are not positioned
  // We must do it now
  if (face_version == 0 || face_version == 5) {
    ItemsOwnerBuilder owner_builder(m_mesh);
    owner_builder.computeFacesOwner();
  }
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
void FaceUniqueIdBuilder::
_checkNoDuplicate()
{
  info() << "Check no duplicate face uniqueId";
  ItemInternalMap& faces_map = m_mesh->facesMap();
  std::unordered_set<Int64> checked_faces_map;
  faces_map.eachItem([&](Item face) {
    ItemUniqueId uid = face.uniqueId();
    auto p = checked_faces_map.find(uid);
    if (p != checked_faces_map.end()) {
      pwarning() << "Duplicate Face UniqueId=" << uid;
      ARCANE_FATAL("Duplicate Face uniqueId={0}", uid);
    }
    checked_faces_map.insert(uid);
  });
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
class T_CellFaceInfo
{
 public:
 
  T_CellFaceInfo(Int64 uid, Integer nb_back_face, Integer nb_true_boundary_face)
  : m_unique_id(uid)
  , m_nb_back_face(nb_back_face)
  , m_nb_true_boundary_face(nb_true_boundary_face)
  {
  }
 
  T_CellFaceInfo()
  : m_unique_id(NULL_ITEM_ID)
  , m_nb_back_face(0)
  , m_nb_true_boundary_face(0)
  {
  }
 
 public:
 
  bool operator<(const T_CellFaceInfo& ci) const
  {
    return m_unique_id < ci.m_unique_id;
  }
 
 public:
 
  Int64 m_unique_id;
  Int64 m_nb_back_face;
  Int64 m_nb_true_boundary_face;
};
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
void FaceUniqueIdBuilder::
_computeFacesUniqueIdsParallelV1()
{
  IParallelMng* pm = m_mesh->parallelMng();
  Integer my_rank = pm->commRank();
  Integer nb_rank = pm->commSize();
 
  Integer nb_local_face = m_mesh_builder->oneMeshItemAdder()->nbFace();
  Integer nb_local_cell = m_mesh_builder->oneMeshItemAdder()->nbCell();
  bool is_verbose = m_mesh_builder->isVerbose();
 
  UniqueArray<Int64> faces_opposite_cell_uid(nb_local_face);
  faces_opposite_cell_uid.fill(NULL_ITEM_ID);
  UniqueArray<Integer> faces_opposite_cell_index(nb_local_face);
  UniqueArray<Integer> faces_opposite_cell_owner(nb_local_face);
 
  // For verification, ensures that all elements of this array
  // are valid, which means that all faces have been
  // renumbered
  UniqueArray<Int64> faces_new_uid(nb_local_face);
  faces_new_uid.fill(NULL_ITEM_ID);
 
  Integer nb_recv_sub_domain_boundary_face = 0;
 
  Int64UniqueArray faces_infos;
  faces_infos.reserve(10000);
  ItemInternalMap& cells_map = m_mesh->cellsMap();
  ItemInternalMap& faces_map = m_mesh->facesMap();
  ItemInternalMap& nodes_map = m_mesh->nodesMap();
 
  // NOTE: this array is not useful on all meshes. It
  // is enough that it contains the meshes that we need, that is to say
  // ours + those connected to one of our faces. A hash table
  // would be more appropriate.
  HashTableMapT<Int64, Int64> cells_first_face_uid(m_mesh_builder->oneMeshItemAdder()->nbCell() * 2, true);
 
  // Gather data from other processors into recv_cells;
  // To prevent the arrays from being too large, we proceed in several
  // steps.
  // Each sub-domain builds its list of boundary faces, with for each face:
  // - its type
  // - the list of its nodes,
  // - the unique number of its cell
  // - the owner of its cell
  // - its index in its cell
  // This list will then be sent to all sub-domains.
  {
    ItemTypeMng* itm = m_mesh->itemTypeMng();
 
    UniqueArray<Int32> faces_local_id;
 
    faces_map.eachItem([&](Face face) {
      bool boundary_val = face.isSubDomainBoundary();
      if (boundary_val)
        faces_local_id.add(face.localId());
    });
 
    Integer nb_sub_domain_boundary_face = faces_local_id.size();
    Int64 global_nb_boundary_face = pm->reduce(Parallel::ReduceSum, (Int64)nb_sub_domain_boundary_face);
    debug() << "NB BOUNDARY FACE=" << nb_sub_domain_boundary_face
            << " NB_FACE=" << nb_local_face
            << " GLOBAL_NB_BOUNDARY_FACE=" << global_nb_boundary_face;
 
    Int64UniqueArray faces_infos2;
    Int64UniqueArray recv_faces_infos;
 
    // Calculate the size of a send block
    // The memory required for a face is equal to nb_node + 4.
    // If we assume we have quadrangles in general, this
    // makes 8 Int64 per face, or 64 bytes per face.
    // The memory required to send everything is therefore 64 * global_nb_boundary_face.
    // step_size * nb_proc * 64 bytes.
    // The default step_size is calculated so that the required memory
    // is on the order of 100 Mo for each message.
    Int64 step_size = 1500000;
    Integer nb_phase = CheckedConvert::toInteger((global_nb_boundary_face / step_size) + 1);
    FaceLocalIdToFaceConverter faces(m_mesh->faceFamily());
    for (Integer i_phase = 0; i_phase < nb_phase; ++i_phase) {
      Integer nb_face_to_send = nb_sub_domain_boundary_face / nb_phase;
      Integer first_face_to_send = nb_face_to_send * i_phase;
      Integer last_face_to_send = first_face_to_send + nb_face_to_send;
      if (i_phase + 1 == nb_phase)
        last_face_to_send = nb_sub_domain_boundary_face;
      Integer real_nb_face_to_send = last_face_to_send - first_face_to_send;
 
      faces_infos2.clear();
      for (Integer i_face = first_face_to_send; i_face < first_face_to_send + real_nb_face_to_send; ++i_face) {
        Face face(faces[faces_local_id[i_face]]);
        face.mutableItemBase().addFlags(ItemFlags::II_Shared | ItemFlags::II_SubDomainBoundary);
        bool has_back_cell = face.itemBase().flags() & ItemFlags::II_HasBackCell;
        faces_infos2.add(face.type());
        for (Node node : face.nodes())
          faces_infos2.add(node.uniqueId().asInt64());
 
        //info() << " ADD FACE lid=" << face->localId();
 
        Cell cell = face.cell(0);
        faces_infos2.add(cell.uniqueId().asInt64());
        faces_infos2.add(cell.owner());
 
        Integer face_index_in_cell = 0;
        if (has_back_cell) {
          for (Face current_face_in_cell : cell.faces()) {
            if (current_face_in_cell == face)
              break;
            if (current_face_in_cell.backCell() == cell)
              ++face_index_in_cell;
          }
        }
        else
          face_index_in_cell = NULL_ITEM_ID;
        faces_infos2.add(face_index_in_cell);
      }
      faces_infos2.add(IT_NullType); // To indicate that the list ends
 
      pm->allGatherVariable(faces_infos2, recv_faces_infos);
 
      info() << "Number of face bytes received: " << recv_faces_infos.size()
             << " phase=" << i_phase << "/" << nb_phase
             << " first_face=" << first_face_to_send
             << " last_face=" << last_face_to_send
             << " nb=" << real_nb_face_to_send;
 
      Integer recv_faces_infos_index = 0;
 
      for (Integer i_sub_domain = 0; i_sub_domain < nb_rank; ++i_sub_domain) {
        bool is_end = false;
        // We must not read the info that comes from me
        if (i_sub_domain == my_rank) {
          recv_faces_infos_index += faces_infos2.size();
          continue;
        }
        // Deserializes the info for each subdomain
        while (!is_end) {
          Integer face_type = CheckedConvert::toInteger(recv_faces_infos[recv_faces_infos_index]);
          ++recv_faces_infos_index;
          if (face_type == IT_NullType) {
            is_end = true;
            break;
          }
          ItemTypeInfo* itt = itm->typeFromId(face_type);
          Integer face_nb_node = itt->nbLocalNode();
          ConstArrayView<Int64> faces_nodes_uid(face_nb_node, &recv_faces_infos[recv_faces_infos_index]);
 
          recv_faces_infos_index += face_nb_node;
          Int64 cell_uid = recv_faces_infos[recv_faces_infos_index];
          ++recv_faces_infos_index;
          Integer cell_owner = CheckedConvert::toInteger(recv_faces_infos[recv_faces_infos_index]);
          ++recv_faces_infos_index;
          Integer cell_face_index = CheckedConvert::toInteger(recv_faces_infos[recv_faces_infos_index]);
          ++recv_faces_infos_index;
 
          Node node = nodes_map.tryFind(faces_nodes_uid[0]);
          // If the face does not exist in my subdomain, it is not of interest to me
          if (node.null())
            continue;
          Face face = ItemTools::findFaceInNode2(node, face_type, faces_nodes_uid);
          if (face.null())
            continue;
          ++nb_recv_sub_domain_boundary_face;
          faces_opposite_cell_uid[face.localId()] = cell_uid;
          faces_opposite_cell_index[face.localId()] = cell_face_index;
          faces_opposite_cell_owner[face.localId()] = cell_owner;
          cells_first_face_uid.add(cell_uid, -1);
        }
      }
    }
    info() << "Number of faces on the subdomain interface: "
           << nb_sub_domain_boundary_face << ' ' << nb_recv_sub_domain_boundary_face;
  }
 
  // Finds the max uniqueId of the meshes across all subdomains.
  Int64 max_cell_uid = 0;
  Int32 max_cell_local_id = 0;
  cells_map.eachItem([&](Item cell) {
    Int64 cell_uid = cell.uniqueId().asInt64();
    Int32 cell_local_id = cell.localId();
    if (cell_uid > max_cell_uid)
      max_cell_uid = cell_uid;
    if (cell_local_id > max_cell_local_id)
      max_cell_local_id = cell_local_id;
  });
  Int64 global_max_cell_uid = pm->reduce(Parallel::ReduceMax, max_cell_uid);
  debug() << "GLOBAL MAX CELL UID=" << global_max_cell_uid;
 
  UniqueArray<T_CellFaceInfo> my_cells_faces_info;
  my_cells_faces_info.reserve(nb_local_cell);
  IntegerUniqueArray my_cells_nb_back_face(max_cell_local_id + 1);
  my_cells_nb_back_face.fill(0);
 
  cells_map.eachItem([&](Cell cell) {
    Int64 cell_uid = cell.uniqueId().asInt64();
    Int32 cell_local_id = cell.localId();
    Integer nb_back_face = 0;
    Integer nb_true_boundary_face = 0;
    for (Face face : cell.faces()) {
      Int64 opposite_cell_uid = faces_opposite_cell_uid[face.localId()];
      if (face.backCell() == cell)
        ++nb_back_face;
      else if (face.nbCell() == 1 && opposite_cell_uid == NULL_ITEM_ID) {
        ++nb_true_boundary_face;
      }
    }
    my_cells_nb_back_face[cell_local_id] = nb_back_face;
    my_cells_faces_info.add(T_CellFaceInfo(cell_uid, nb_back_face, nb_true_boundary_face));
  });
  std::sort(std::begin(my_cells_faces_info), std::end(my_cells_faces_info));
 
  {
    Integer nb_phase = 16;
    Integer first_cell_index_to_send = 0;
    Int64 current_face_uid = 0;
 
    for (Integer i_phase = 0; i_phase < nb_phase; ++i_phase) {
      Integer nb_uid_to_send = CheckedConvert::toInteger(global_max_cell_uid / nb_phase);
      Integer first_uid_to_send = nb_uid_to_send * i_phase;
      Int64 last_uid_to_send = first_uid_to_send + nb_uid_to_send;
      if (i_phase + 1 == nb_phase)
        last_uid_to_send = global_max_cell_uid;
 
      //Integer last_cell_index_to_send = first_cell_index_to_send;
      Integer nb_cell_to_send = 0;
      for (Integer zz = first_cell_index_to_send, zs = my_cells_faces_info.size(); zz < zs; ++zz) {
        if (my_cells_faces_info[zz].m_unique_id <= last_uid_to_send)
          ++nb_cell_to_send;
        else
          break;
      }
      debug() << "FIRST TO SEND=" << first_cell_index_to_send
              << " NB=" << nb_cell_to_send
              << " first_uid=" << first_uid_to_send
              << " last_uid=" << last_uid_to_send;
 
      T_CellFaceInfo* begin_cell_array = my_cells_faces_info.data() + first_cell_index_to_send;
      Int64* begin_array = reinterpret_cast<Int64*>(begin_cell_array);
      Integer begin_size = nb_cell_to_send * 3;
 
      Int64ConstArrayView cells_faces_infos(begin_size, begin_array);
 
      Int64UniqueArray recv_cells_faces_infos;
      pm->allGatherVariable(cells_faces_infos, recv_cells_faces_infos);
      first_cell_index_to_send += nb_cell_to_send;
 
      info() << "Infos faces (received) nb_int64=" << recv_cells_faces_infos.size();
      Integer recv_nb_cell = recv_cells_faces_infos.size() / 3;
 
      // NOTE: since we know the possible min and max uid, we can optimize by
      // creating an array dimensioned with this min and max as bounds and
      // filling the elements of this array directly. This way, we
      UniqueArray<T_CellFaceInfo> global_cells_faces_info(recv_nb_cell);
      for (Integer i = 0; i < recv_nb_cell; ++i) {
        Int64 cell_uid = recv_cells_faces_infos[i * 3];
        global_cells_faces_info[i].m_unique_id = cell_uid;
        global_cells_faces_info[i].m_nb_back_face = recv_cells_faces_infos[(i * 3) + 1];
        global_cells_faces_info[i].m_nb_true_boundary_face = recv_cells_faces_infos[(i * 3) + 2];
      }
      info() << "Sorting the faces nb=" << global_cells_faces_info.size();
      std::sort(std::begin(global_cells_faces_info), std::end(global_cells_faces_info));
 
      for (Integer i = 0; i < recv_nb_cell; ++i) {
        Int64 cell_uid = global_cells_faces_info[i].m_unique_id;
        if (cells_map.hasKey(cell_uid) || cells_first_face_uid.hasKey(cell_uid))
          cells_first_face_uid.add(cell_uid, current_face_uid);
        current_face_uid += global_cells_faces_info[i].m_nb_back_face + global_cells_faces_info[i].m_nb_true_boundary_face;
      }
    }
  }
 
  cells_map.eachItem([&](Cell cell) {
    Int64 cell_uid = cell.uniqueId();
    Int32 cell_local_id = cell.localId();
    Integer num_local_face = 0;
    Integer num_true_boundary_face = 0;
    for (Face face : cell.faces()) {
      Int64 opposite_cell_uid = faces_opposite_cell_uid[face.localId()];
      Int64 face_new_uid = NULL_ITEM_UNIQUE_ID;
      if (face.backCell() == cell) {
        if (!cells_first_face_uid.hasKey(cell_uid))
          fatal() << "NO KEY 0 for cell_uid=" << cell_uid;
        face_new_uid = cells_first_face_uid[cell_uid] + num_local_face;
        face.mutableItemBase().setOwner(my_rank, my_rank);
        ++num_local_face;
      }
      else if (face.nbCell() == 1) {
        if (opposite_cell_uid == NULL_ITEM_UNIQUE_ID) {
          // This is a boundary face of the initial domain
          if (!cells_first_face_uid.hasKey(cell_uid))
            fatal() << "NO KEY 1 for cell_uid=" << cell_uid;
          face_new_uid = cells_first_face_uid[cell_uid] + my_cells_nb_back_face[cell_local_id] + num_true_boundary_face;
          ++num_true_boundary_face;
          face.mutableItemBase().setOwner(my_rank, my_rank);
        }
        else {
          if (!cells_first_face_uid.hasKey(opposite_cell_uid))
            fatal() << "NO KEY 1 for cell_uid=" << cell_uid << " opoosite=" << opposite_cell_uid;
          face_new_uid = cells_first_face_uid[opposite_cell_uid] + faces_opposite_cell_index[face.localId()];
          face.mutableItemBase().setOwner(faces_opposite_cell_owner[face.localId()], my_rank);
        }
      }
      if (face_new_uid != NULL_ITEM_UNIQUE_ID) {
        faces_new_uid[face.localId()] = face_new_uid;
        face.mutableItemBase().setUniqueId(face_new_uid);
      }
    }
  });
 
  // Verifies that all faces have been re-indexed
  {
    Integer nb_error = 0;
    for (Integer i = 0, is = nb_local_face; i < is; ++i) {
      if (faces_new_uid[i] == NULL_ITEM_UNIQUE_ID) {
        ++nb_error;
        if (nb_error < 10)
          error() << "The face lid=" << i << " has not been re-indexed.";
      }
    }
    if (nb_error != 0)
      ARCANE_FATAL("Some ({0}) faces have not been reindexed", nb_error);
  }
 
  if (is_verbose) {
    OStringStream ostr;
    cells_map.eachItem([&](Cell cell) {
      Int64 cell_uid = cell.uniqueId().asInt64();
      Integer face_index = 0;
      for (Face face : cell.faces()) {
        Int64 opposite_cell_uid = faces_opposite_cell_uid[face.localId()];
        bool shared = false;
        bool true_boundary = false;
        bool internal_other = false;
        if (face.backCell() == cell) {
        }
        else if (face.nbCell() == 1) {
          if (opposite_cell_uid == NULL_ITEM_ID)
            true_boundary = true;
          else
            shared = true;
        }
        else {
          internal_other = true;
          opposite_cell_uid = face.backCell().uniqueId().asInt64();
        }
        ostr() << "NEW UNIQUE ID FOR FACE"
               << " lid=" << face.localId()
               << " cell=" << cell_uid
               << " face=" << face.uniqueId()
               << " nbcell=" << face.nbCell()
               << " cellindex=" << face_index << " (";
        for (Node node : face.nodes())
          ostr() << ' ' << node.uniqueId();
        ostr() << ")";
        if (internal_other)
          ostr() << " internal-other";
        if (true_boundary)
          ostr() << " true-boundary";
        if (opposite_cell_uid != NULL_ITEM_ID) {
          ostr() << " opposite " << opposite_cell_uid;
        }
        if (shared)
          ostr() << " (shared)";
        ostr() << "\n";
        ++face_index;
      }
    });
    info() << ostr.str();
    String file_name("faces_uid.");
    file_name = file_name + my_rank;
    std::ofstream ofile(file_name.localstr());
    ofile << ostr.str();
  }
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
void FaceUniqueIdBuilder::
_exchangeData(IParallelExchanger* exchanger, BoundaryInfosMap& boundary_infos_to_send)
{
  for (BoundaryInfosMapEnumerator i_map(boundary_infos_to_send); ++i_map;) {
    Int32 sd = i_map.data()->key();
    exchanger->addSender(sd);
  }
  exchanger->initializeCommunicationsMessages();
  Integer nb_sender = exchanger->nbSender();
  Integer nb_receiver = exchanger->nbReceiver();
  info() << "NB_SEND=" << nb_sender << " NB_RECV=" << nb_receiver;
  Integer total = nb_sender + nb_receiver;
  Integer global_total = exchanger->parallelMng()->reduce(Parallel::ReduceSum, total);
  info() << "GLOBAL_NB_MESSAGE=" << global_total;
 
  {
    for (Integer i = 0, ns = exchanger->nbSender(); i < ns; ++i) {
      ISerializeMessage* sm = exchanger->messageToSend(i);
      Int32 rank = sm->destination().value();
      ISerializer* s = sm->serializer();
      Int64ConstArrayView infos = boundary_infos_to_send[rank];
      Integer nb_info = infos.size();
      s->setMode(ISerializer::ModeReserve);
      s->reserveInt64(1); // For the number of elements
      s->reserveSpan(eBasicDataType::Int64, nb_info); // For the elements
      s->allocateBuffer();
      s->setMode(ISerializer::ModePut);
      s->putInt64(nb_info);
      s->putSpan(infos);
    }
  }
  exchanger->processExchange();
  debug() << "END EXCHANGE";
}
 
template <typename DataType>
class ItemInfoMultiList
{
 public:
 private:
 
  class MyInfo
  {
   public:
 
    MyInfo(const DataType& d, Integer n)
    : data(d)
    , next_index(n)
    {}
 
   public:
 
    DataType data;
    Integer next_index;
  };
 
 public:
 
  ItemInfoMultiList()
  : m_last_index(5000, true)
  {}
 
 public:
 
  void add(Int64 node_uid, const DataType& data)
  {
    Integer current_index = m_values.size();
 
    bool is_add = false;
    HashTableMapT<Int64, Int32>::Data* d = m_last_index.lookupAdd(node_uid, -1, is_add);
 
    m_values.add(MyInfo(data, d->value()));
    d->value() = current_index;
  }
 
 public:
 
  UniqueArray<MyInfo> m_values;
  HashTableMapT<Int64, Int32> m_last_index;
};
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
void FaceUniqueIdBuilder::
_computeFacesUniqueIdsParallelV2()
{
  IParallelMng* pm = m_mesh->parallelMng();
  Integer my_rank = pm->commRank();
  Integer nb_rank = pm->commSize();
 
  Integer nb_local_face = m_mesh_builder->oneMeshItemAdder()->nbFace();
  //Integer nb_local_cell = m_mesh_builder->nbCell();
  //bool is_verbose = m_mesh_builder->isVerbose();
 
  Int64UniqueArray faces_opposite_cell_uid(nb_local_face);
  faces_opposite_cell_uid.fill(NULL_ITEM_ID);
  IntegerUniqueArray faces_opposite_cell_index(nb_local_face);
  IntegerUniqueArray faces_opposite_cell_owner(nb_local_face);
 
  // For verification, ensures that all elements of this array
  // are valid, which means that all faces have been renumbered.
  Int64UniqueArray faces_new_uid(nb_local_face);
  faces_new_uid.fill(NULL_ITEM_ID);
 
  Int64UniqueArray faces_infos;
  faces_infos.reserve(10000);
  ItemInternalMap& faces_map = m_mesh->facesMap();
  ItemInternalMap& nodes_map = m_mesh->nodesMap();
 
  // NOTE: this array is not useful on all meshes. It
  // is enough that it contains the meshes we need, that is,
  // ours + those connected to one of our faces.
  HashTableMapT<Int32, Int32> cell_first_face_uid(m_mesh_builder->oneMeshItemAdder()->nbCell() * 2, true);
 
  // Collects data from other processors into recv_cells;
  // To prevent the arrays from being too large, we proceed in several
  // steps.
  // Each subdomain builds its list of boundary faces, for each face:
  // - its type
  // - the list of its nodes,
  // - the unique ID of its mesh
  // - the owner of its mesh
  // - its index in its mesh
  // This list will then be sent to all subdomains.
  ItemTypeMng* itm = m_mesh->itemTypeMng();
 
  // Determines the max unique id of the nodes
  Int64 my_max_node_uid = NULL_ITEM_UNIQUE_ID;
  nodes_map.eachItem([&](Item node) {
    Int64 node_uid = node.uniqueId();
    if (node_uid > my_max_node_uid)
      my_max_node_uid = node_uid;
  });
  Int64 global_max_node_uid = pm->reduce(Parallel::ReduceMax, my_max_node_uid);
  debug() << "NODE_UID_INFO: MY_MAX_UID=" << my_max_node_uid
          << " GLOBAL=" << global_max_node_uid;
 
  //TODO: choose a good value to initialize the table
  BoundaryInfosMap boundary_infos_to_send(nb_rank, true);
  NodeUidToSubDomain uid_to_subdomain_converter(global_max_node_uid, nb_rank);
  info() << "NB_CORE modulo=" << uid_to_subdomain_converter.modulo();
  HashTableMapT<Int64, SharedArray<Int64>> nodes_info(100000, true);
  IItemFamily* node_family = m_mesh->nodeFamily();
  UniqueArray<bool> is_boundary_nodes(node_family->maxLocalId(), false);
 
  // Marks all boundary nodes because these are the ones that need to be sent
  faces_map.eachItem([&](Face face) {
    Integer face_nb_cell = face.nbCell();
    if (face_nb_cell == 1) {
      for (Node node : face.nodes())
        is_boundary_nodes[node.localId()] = true;
    }
  });
 
  // Determines the list of boundary faces
  faces_map.eachItem([&](Face face) {
    Node first_node = face.node(0);
    Int64 first_node_uid = first_node.uniqueId();
    SharedArray<Int64> v;
    Int32 dest_rank = -1;
    if (!is_boundary_nodes[first_node.localId()]) {
      v = nodes_info.lookupAdd(first_node_uid)->value();
    }
    else {
      dest_rank = uid_to_subdomain_converter.uidToRank(first_node_uid);
      v = boundary_infos_to_send.lookupAdd(dest_rank)->value();
    }
    v.add(first_node_uid); // 0
    v.add(my_rank); // 1
    v.add(face.uniqueId()); // 2
    v.add(face.type()); // 3
    Cell back_cell = face.backCell();
    Cell front_cell = face.frontCell();
    if (back_cell.null()) // 4 : only used for debug
      v.add(NULL_ITEM_UNIQUE_ID);
    else
      v.add(back_cell.uniqueId());
    if (front_cell.null()) // 5 : only used for debug
      v.add(NULL_ITEM_UNIQUE_ID);
    else
      v.add(front_cell.uniqueId());
    for (Integer z = 0, zs = face.nbNode(); z < zs; ++z)
      v.add(face.node(z).uniqueId());
  });
 
  // Positions the list of sends
  Ref<IParallelExchanger> exchanger{ ParallelMngUtils::createExchangerRef(pm) };
  _exchangeData(exchanger.get(), boundary_infos_to_send);
 
  {
    Integer nb_receiver = exchanger->nbReceiver();
    debug() << "NB RECEIVER=" << nb_receiver;
    Int64UniqueArray received_infos;
    for (Integer i = 0; i < nb_receiver; ++i) {
      ISerializeMessage* sm = exchanger->messageToReceive(i);
      //Int32 orig_rank = sm->destSubDomain();
      ISerializer* s = sm->serializer();
      s->setMode(ISerializer::ModeGet);
      Int64 nb_info = s->getInt64();
      //info() << "RECEIVE NB_INFO=" << nb_info << " from=" << orig_rank;
      received_infos.resize(nb_info);
      s->getSpan(received_infos);
      //if ((nb_info % 3)!=0)
      //fatal() << "info size can not be divided by 3";
      Integer z = 0;
      while (z < nb_info) {
        Int64 node_uid = received_infos[z + 0];
        Int32 face_type = (Int32)received_infos[z + 3];
        ItemTypeInfo* itt = itm->typeFromId(face_type);
        Integer face_nb_node = itt->nbLocalNode();
        Int64Array& a = nodes_info.lookupAdd(node_uid)->value();
        a.addRange(Int64ConstArrayView(6 + face_nb_node, &received_infos[z]));
        z += 6;
        z += face_nb_node;
      }
    }
    Integer my_max_face_node = 0;
    for (HashTableMapT<Int64, SharedArray<Int64>>::Enumerator inode(nodes_info); ++inode;) {
      Int64ConstArrayView a = *inode;
      Integer nb_info = a.size();
      Integer z = 0;
      Integer node_nb_face = 0;
      while (z < nb_info) {
        ++node_nb_face;
        Int32 face_type = (Int32)a[z + 3];
        ItemTypeInfo* itt = itm->typeFromId(face_type);
        Integer face_nb_node = itt->nbLocalNode();
        z += 6;
        z += face_nb_node;
      }
      my_max_face_node = math::max(node_nb_face, my_max_face_node);
    }
    Integer global_max_face_node = pm->reduce(Parallel::ReduceMax, my_max_face_node);
    debug() << "GLOBAL MAX FACE NODE=" << global_max_face_node;
    // OK, maintenant donne comme uid de la face (node_uid * global_max_face_node + index)
    IntegerUniqueArray indexes;
    boundary_infos_to_send = BoundaryInfosMap(nb_rank, true);
 
    for (HashTableMapT<Int64, SharedArray<Int64>>::Enumerator inode(nodes_info); ++inode;) {
      Int64ConstArrayView a = *inode;
      Integer nb_info = a.size();
      Integer z = 0;
      Integer node_nb_face = 0;
      indexes.clear();
      while (z < nb_info) {
        Int64 node_uid = a[z + 0];
        Int32 sender_rank = (Int32)a[z + 1];
        Int64 face_uid = a[z + 2];
        Int32 face_type = (Int32)a[z + 3];
        ItemTypeInfo* itt = itm->typeFromId(face_type);
        Integer face_nb_node = itt->nbLocalNode();
 
        // Checks if the face is already in the list:
        Integer face_index = node_nb_face;
        Int32 face_new_owner = sender_rank;
        for (Integer y = 0; y < node_nb_face; ++y) {
          if (memcmp(&a[indexes[y] + 6], &a[z + 6], sizeof(Int64) * face_nb_node) == 0) {
            face_index = y;
            face_new_owner = (Int32)a[indexes[y] + 1];
          }
        }
        Int64 face_new_uid = (node_uid * global_max_face_node) + face_index;
        Int64Array& v = boundary_infos_to_send.lookupAdd(sender_rank)->value();
        // Indicates to the owner of this face its new uid
        v.add(face_uid);
        v.add(face_new_uid);
        v.add(face_new_owner);
        indexes.add(z);
        z += 6;
        z += face_nb_node;
        ++node_nb_face;
      }
      my_max_face_node = math::max(node_nb_face, my_max_face_node);
    }
  }
  exchanger = ParallelMngUtils::createExchangerRef(pm);
 
  _exchangeData(exchanger.get(), boundary_infos_to_send);
  {
    Integer nb_receiver = exchanger->nbReceiver();
    debug() << "NB RECEIVER=" << nb_receiver;
    Int64UniqueArray received_infos;
    for (Integer i = 0; i < nb_receiver; ++i) {
      ISerializeMessage* sm = exchanger->messageToReceive(i);
      ISerializer* s = sm->serializer();
      s->setMode(ISerializer::ModeGet);
      Int64 nb_info = s->getInt64();
      received_infos.resize(nb_info);
      s->getSpan(received_infos);
      if ((nb_info % 3) != 0)
        ARCANE_FATAL("info size can not be divided by 3 v={0}", nb_info);
      ;
      Int64 nb_item = nb_info / 3;
      for (Int64 z = 0; z < nb_item; ++z) {
        Int64 old_uid = received_infos[(z * 3)];
        Int64 new_uid = received_infos[(z * 3) + 1];
        Int32 new_owner = (Int32)received_infos[(z * 3) + 2];
        impl::MutableItemBase face(faces_map.tryFind(old_uid));
        if (face.null())
          ARCANE_FATAL("Can not find own face uid={0}", old_uid);
        face.setUniqueId(new_uid);
        face.setOwner(new_owner, my_rank);
      }
    }
  }
 
  traceMng()->flush();
  pm->barrier();
  debug() << "END OF TEST NEW FACE COMPUTE";
  return;
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
void FaceUniqueIdBuilder::
_computeFacesUniqueIdsSequential()
{
  bool is_verbose = m_mesh_builder->isVerbose();
 
  ItemInternalMap& cells_map = m_mesh->cellsMap();
 
  // In sequential mode, the uniqueIds() of the meshes cannot exceed the
  // size of Integers even in 32 bits.
  Int32 max_uid = 0;
  cells_map.eachItem([&](Item cell) {
    Int32 cell_uid = cell.uniqueId().asInt32();
    if (cell_uid > max_uid)
      max_uid = cell_uid;
  });
  info() << "Max uid=" << max_uid;
  Integer nb_computed = max_uid + 1;
  Int32UniqueArray cell_first_face_uid(nb_computed, 0);
  Int32UniqueArray cell_nb_num_back_face(nb_computed, 0);
  Int32UniqueArray cell_true_boundary_face(nb_computed, 0);
 
  cells_map.eachItem([&](Cell cell) {
    Int32 cell_uid = cell.uniqueId().asInt32();
    Integer nb_num_back_face = 0;
    Integer nb_true_boundary_face = 0;
    for (Face face : cell.faces()) {
      if (face.backCell() == cell)
        ++nb_num_back_face;
      else if (face.nbCell() == 1) {
        ++nb_true_boundary_face;
      }
    }
    cell_nb_num_back_face[cell_uid] = nb_num_back_face;
    cell_true_boundary_face[cell_uid] = nb_true_boundary_face;
  });
 
  Integer current_face_uid = 0;
  for (Integer i = 0; i < nb_computed; ++i) {
    cell_first_face_uid[i] = current_face_uid;
    current_face_uid += cell_nb_num_back_face[i] + cell_true_boundary_face[i];
  }
 
  if (is_verbose) {
    cells_map.eachItem([&](Item cell) {
      Int32 i = cell.uniqueId().asInt32();
      info() << "Recv: Cell FaceInfo celluid=" << i
             << " firstfaceuid=" << cell_first_face_uid[i]
             << " nbback=" << cell_nb_num_back_face[i]
             << " nbbound=" << cell_true_boundary_face[i];
    });
  }
 
  cells_map.eachItem([&](Cell cell) {
    Int32 cell_uid = cell.uniqueId().asInt32();
    Integer nb_num_back_face = 0;
    Integer nb_true_boundary_face = 0;
    for (Face face : cell.faces()) {
      Int64 face_new_uid = NULL_ITEM_UNIQUE_ID;
      if (face.backCell() == cell) {
        face_new_uid = cell_first_face_uid[cell_uid] + nb_num_back_face;
        ++nb_num_back_face;
      }
      else if (face.nbCell() == 1) {
        face_new_uid = cell_first_face_uid[cell_uid] + cell_nb_num_back_face[cell_uid] + nb_true_boundary_face;
        ++nb_true_boundary_face;
      }
      if (face_new_uid != NULL_ITEM_UNIQUE_ID) {
        face.mutableItemBase().setUniqueId(face_new_uid);
      }
    }
  });
 
  if (is_verbose) {
    OStringStream ostr;
    cells_map.eachItem([&](Cell cell) {
      Integer face_index = 0;
      for (Face face : cell.faces()) {
        Int64 opposite_cell_uid = NULL_ITEM_UNIQUE_ID;
        bool true_boundary = false;
        bool internal_other = false;
        if (face.backCell() == cell) {
        }
        else if (face.nbCell() == 1) {
          true_boundary = true;
        }
        else {
          internal_other = true;
          opposite_cell_uid = face.backCell().uniqueId().asInt64();
        }
        ostr() << "NEW LOCAL ID FOR CELLFACE cell_uid=" << cell.uniqueId() << ' '
               << face_index << " uid=" << face.uniqueId() << " (";
        for (Node node : face.nodes())
          ostr() << ' ' << node.uniqueId();
        ostr() << ")";
        if (internal_other)
          ostr() << " internal-other";
        if (true_boundary)
          ostr() << " true-boundary";
        if (opposite_cell_uid != NULL_ITEM_ID)
          ostr() << " opposite " << opposite_cell_uid;
        ostr() << '\n';
        ++face_index;
      }
    });
    info() << ostr.str();
  }
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
} // End namespace Arcane::mesh
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/