neighbor_exchanger.hpp

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#ifndef SRC_EXCHANGER_NEIGHBOR_EXCHANGER_HPP_
#define SRC_EXCHANGER_NEIGHBOR_EXCHANGER_HPP_
 
// athena
#include <athena/globals.hpp>
#include <athena/mesh/mesh.hpp>
 
// canoe
#include <configure.hpp>
 
// exchanger
#include "exchanger.hpp"
 
#ifdef MPI_PARALLEL
#include <mpi.h>
#endif
 
template <typename T>
void NeighborExchanger<T>::Transfer(MeshBlock const *pmb, int n) {
  for (auto &nb : pmb->pbval->neighbor) {
    if (nb.snb.rank == Globals::my_rank) {  // on the same process
      MeshBlock *neighbor = pmb->pmy_mesh->FindMeshBlock(nb.snb.gid);
      auto exchanger = static_cast<NeighborExchanger<T> *>(
          neighbor->pimpl->GetExchanger(MessageTraits<T>::name));
      exchanger->recv_buffer_[nb.targetid].swap(send_buffer_[nb.bufid]);
      exchanger->SetBoundaryStatus(nb.targetid, BoundaryStatus::arrived);
    }
#ifdef MPI_PARALLEL
    else {  // MPI
      int tag = MessageHelper::create_mpi_tag(nb.snb.lid, nb.targetid,
                                              MessageTraits<T>::name);
      int ssize = send_buffer_[nb.bufid].size();
      MPI_Isend(send_buffer_[nb.bufid].data(), ssize,
                MessageTraits<T>::mpi_type, nb.snb.rank, tag, mpi_comm_,
                &req_mpi_send_[nb.bufid]);
    }
#endif
  }
 
  int rsize, tag;
 
#ifdef MPI_PARALLEL
  MPI_Status status;
  for (auto &nb : pmb->pbval->neighbor) {
    if (nb.snb.rank == Globals::my_rank) continue;  // local boundary received
 
    int tag = MessageHelper::create_mpi_tag(pmb->lid, nb.bufid,
                                            MessageTraits<T>::name);
 
    MPI_Probe(nb.snb.rank, tag, MPI_COMM_WORLD, &status);
    MPI_Get_count(&status, MessageTraits<T>::mpi_type, &rsize);
 
    recv_buffer_[nb.bufid].resize(rsize);
    MPI_Irecv(recv_buffer_[nb.bufid].data(), rsize, MessageTraits<T>::mpi_type,
              nb.snb.rank, tag, mpi_comm_, &req_mpi_recv_[nb.bufid]);
  }
#endif
}
 
template <typename T>
void NeighborExchanger<T>::ClearBuffer(MeshBlock const *pmb) {
  for (auto &nb : pmb->pbval->neighbor) {
#ifdef MPI_PARALLEL
    if (nb.snb.rank != Globals::my_rank)
      MPI_Wait(&req_mpi_send_[nb.bufid], MPI_STATUS_IGNORE);
#endif
  }
}
 
#endif  // SRC_EXCHANGER_NEIGHBOR_EXCHANGER_HPP_