MueLu_IsolatedNodeAggregationAlgorithm_kokkos_def.hpp

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#ifndef MUELU_ISOLATEDNODEAGGREGATIONALGORITHM_KOKKOS_DEF_HPP
#define MUELU_ISOLATEDNODEAGGREGATIONALGORITHM_KOKKOS_DEF_HPP

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

#include <Xpetra_Vector.hpp>

#include "MueLu_IsolatedNodeAggregationAlgorithm_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>
  void IsolatedNodeAggregationAlgorithm_kokkos<LocalOrdinal, GlobalOrdinal, Node>::
  BuildAggregates(const ParameterList& /* params */,
                  const LWGraph_kokkos& 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);
    }

    auto lclLWGraph = graph.getLocalLWGraph();

    const LO  numRows = graph.GetNodeNumVertices();

    // Remove all isolated nodes
    for (LO i = 0; i < numRows; i++)
      if (aggStat[i] != AGGREGATED && aggStat[i] != IGNORED && lclLWGraph.getNeighborVertices(i).length == 1) {
        aggStat[i] = IGNORED;
        numNonAggregatedNodes--;
      }

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

} // end namespace

#endif // MUELU_ISOLATEDNODEAGGREGATIONALGORITHM_KOKKOS_DEF_HPP