MueLu_OnePtAggregationAlgorithm_kokkos_def.hpp

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#ifndef MUELU_ONEPTAGGREGATIONALGORITHM_DEF_HPP
#define MUELU_ONEPTAGGREGATIONALGORITHM_DEF_HPP

#include <Teuchos_Comm.hpp>
#include <Teuchos_CommHelpers.hpp>

#include <Xpetra_Vector.hpp>

#include "MueLu_OnePtAggregationAlgorithm_kokkos.hpp"

#include "MueLu_LWGraph_kokkos.hpp"
#include "MueLu_Aggregates_kokkos.hpp"
#include "MueLu_Exceptions.hpp"
#include "MueLu_Monitor.hpp"

namespace MueLu {

  template <class LocalOrdinal, class GlobalOrdinal, class Node>
  OnePtAggregationAlgorithm_kokkos<LocalOrdinal, GlobalOrdinal, Node>::OnePtAggregationAlgorithm_kokkos(RCP<const FactoryBase> const &/* graphFact */)
  {
  }

  template <class LocalOrdinal, class GlobalOrdinal, class Node>
  void OnePtAggregationAlgorithm_kokkos<LocalOrdinal, GlobalOrdinal, Node>::
  BuildAggregates(Teuchos::ParameterList const & /* params */,
                  LWGraph_kokkos const & graph,
                  Aggregates_kokkos & aggregates,
                  Kokkos::View<unsigned*, typename LWGraph_kokkos::device_type>& aggstat,
                  LO& numNonAggregatedNodes) const {
    Monitor m(*this, "BuildAggregates");

    typename Kokkos::View<unsigned*, device_type>::HostMirror aggstatHost
      = Kokkos::create_mirror(aggstat);
    Kokkos::deep_copy(aggstatHost, aggstat);
    std::vector<unsigned> aggStat;
    aggStat.resize(aggstatHost.extent(0));
    for(size_t idx = 0; idx < aggstatHost.extent(0); ++idx) {
      aggStat[idx] = aggstatHost(idx);
    }

    const LocalOrdinal nRows = graph.GetNodeNumVertices();
    const int myRank = graph.GetComm()->getRank();

    // vertex ids for output
    Teuchos::ArrayRCP<LocalOrdinal> vertex2AggId = aggregates.GetVertex2AggId()->getDataNonConst(0);
    Teuchos::ArrayRCP<LocalOrdinal> procWinner   = aggregates.GetProcWinner()->getDataNonConst(0);

    // some internal variables
    LocalOrdinal nLocalAggregates = aggregates.GetNumAggregates();    // number of local aggregates on current proc
    LocalOrdinal iNode1  = 0;        // current node

    // main loop over all local rows of graph(A)
    while (iNode1 < nRows) {

      if (aggStat[iNode1] == ONEPT) {

        aggregates.SetIsRoot(iNode1);    // mark iNode1 as root node for new aggregate 'ag'
        std::vector<int> aggList;
        aggList.push_back(iNode1);
        int aggIndex = nLocalAggregates++;

        // finalize aggregate
        for (size_t k = 0; k < aggList.size(); k++) {
          aggStat[aggList[k]] = IGNORED;
          vertex2AggId[aggList[k]] = aggIndex;
          procWinner[aggList[k]] = myRank;
        }
        numNonAggregatedNodes -= aggList.size();
      }

      iNode1++;
    } // end while

    for(size_t idx = 0; idx < aggstatHost.extent(0); ++idx) {
      aggstatHost(idx) = aggStat[idx];
    }
    Kokkos::deep_copy(aggstat, aggstatHost);

    // update aggregate object
    aggregates.SetNumAggregates(nLocalAggregates);
  }

} // end namespace

#endif // MUELU_ONEPTAGGREGATIONALGORITHM_KOKKOS_DEF_HPP