DTK_CenterDistributor_impl.hpp

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//---------------------------------------------------------------------------//
/*
  Copyright (c) 2012, Stuart R. Slattery
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  modification, are permitted provided that the following conditions are
  met:

  *: Redistributions of source code must retain the above copyright
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  *: Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.

  *: Neither the name of the University of Wisconsin - Madison nor the
  names of its contributors may be used to endorse or promote products
  derived from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/
//---------------------------------------------------------------------------//
//---------------------------------------------------------------------------//

#ifndef DTK_CENTERDISTRIBUTOR_IMPL_HPP
#define DTK_CENTERDISTRIBUTOR_IMPL_HPP

#include <algorithm>
#include <limits>

#include <Teuchos_Array.hpp>
#include <Teuchos_CommHelpers.hpp>

#include "DTK_DBC.hpp"

namespace DataTransferKit
{
//---------------------------------------------------------------------------//
template <int DIM>
CenterDistributor<DIM>::CenterDistributor(
    const Teuchos::RCP<const Teuchos::Comm<int>> &comm,
    const Teuchos::ArrayView<const double> &source_centers,
    const Teuchos::ArrayView<const double> &target_centers, const double radius,
    Teuchos::Array<double> &target_decomp_source_centers )
    : d_distributor( new Tpetra::Distributor( comm ) )
{
    DTK_REQUIRE( 0 == source_centers.size() % DIM );
    DTK_REQUIRE( 0 == target_centers.size() % DIM );

    // Build the import/export data.
    Teuchos::Array<int> export_procs;
    {
        // Compute the radius to expand the local domain with.
        double radius_tol = 1.0e-2;
        double radius_expand = radius * ( 1.0 + radius_tol );

        // Gather the bounding domains for each target proc.
        CloudDomain<DIM> local_target_domain =
            localCloudDomain( target_centers );
        local_target_domain.expand( radius_expand );
        Teuchos::Array<CloudDomain<DIM>> global_target_domains(
            comm->getSize() );
        Teuchos::gatherAll<int, CloudDomain<DIM>>(
            *comm, 1, &local_target_domain, global_target_domains.size(),
            global_target_domains.getRawPtr() );

        // Get those that are neighbors to this source proc.
        CloudDomain<DIM> local_source_domain =
            localCloudDomain( source_centers );
        Teuchos::Array<CloudDomain<DIM>> neighbor_target_domains;
        Teuchos::Array<int> neighbor_ranks;
        for ( unsigned i = 0; i < global_target_domains.size(); ++i )
        {
            if ( local_source_domain.checkForIntersection(
                     global_target_domains[i] ) )
            {
                neighbor_target_domains.push_back( global_target_domains[i] );
                neighbor_ranks.push_back( i );
            }
        }
        global_target_domains.clear();

        // Find the procs to which the sources will be sent.
        Teuchos::ArrayView<const double> source_point;
        for ( unsigned source_id = 0; source_id < source_centers.size() / DIM;
              ++source_id )
        {
            source_point = source_centers.view( DIM * source_id, DIM );
            for ( unsigned b = 0; b < neighbor_target_domains.size(); ++b )
            {
                if ( neighbor_target_domains[b].pointInDomain( source_point ) )
                {
                    export_procs.push_back( neighbor_ranks[b] );
                    d_export_ids.push_back( source_id );
                }
            }
        }
    }
    DTK_CHECK( d_export_ids.size() == export_procs.size() );
    d_num_exports = d_export_ids.size();

    // Create the communication plan.
    Teuchos::ArrayView<int> export_procs_view = export_procs();
    d_num_imports = d_distributor->createFromSends( export_procs_view );
    export_procs.clear();

    // Unroll the coordinates to handle cases where single source centers
    // may have multiple destinations.
    Teuchos::Array<unsigned>::const_iterator export_id_it;
    Teuchos::Array<double> src_coords( d_num_exports * DIM );
    for ( int n = 0; n < d_num_exports; ++n )
    {
        src_coords( DIM * n, DIM )
            .assign( source_centers( DIM * d_export_ids[n], DIM ) );
    }

    // Move the source center coordinates to the target decomposition.
    Teuchos::ArrayView<const double> src_coords_view = src_coords();
    target_decomp_source_centers.resize( d_num_imports * DIM );
    d_distributor->doPostsAndWaits( src_coords_view, DIM,
                                    target_decomp_source_centers() );
}

//---------------------------------------------------------------------------//
template <int DIM>
template <class T>
void CenterDistributor<DIM>::distribute(
    const Teuchos::ArrayView<const T> &source_decomp_data,
    const Teuchos::ArrayView<T> &target_decomp_data ) const
{
    DTK_REQUIRE( d_num_imports == target_decomp_data.size() );

    // Unroll the source data to handle cases where single data points may
    // have multiple destinations.
    Teuchos::Array<unsigned>::const_iterator export_id_it;
    Teuchos::Array<T> src_data( d_num_exports );
    typename Teuchos::Array<T>::iterator src_it;
    for ( export_id_it = d_export_ids.begin(), src_it = src_data.begin();
          export_id_it != d_export_ids.end(); ++export_id_it, ++src_it )
    {
        DTK_CHECK( *export_id_it < source_decomp_data.size() );
        *src_it = source_decomp_data[*export_id_it];
    }

    // Distribute.
    Teuchos::ArrayView<const T> src_view = src_data();
    d_distributor->doPostsAndWaits( src_view, 1, target_decomp_data );
}

//---------------------------------------------------------------------------//
template <int DIM>
CloudDomain<DIM> CenterDistributor<DIM>::localCloudDomain(
    const Teuchos::ArrayView<const double> &centers ) const
{
    Teuchos::Array<double> bounds( 2 * DIM, 0.0 );

    if ( centers.size() > 0 )
    {
        for ( int d = 0; d < DIM; ++d )
        {
            bounds[2 * d] = std::numeric_limits<double>::max();
            bounds[2 * d + 1] = std::numeric_limits<double>::min();
        }
    }

    Teuchos::ArrayView<const double>::const_iterator center_it;
    for ( center_it = centers.begin(); center_it != centers.end(); )
    {
        for ( int d = 0; d < DIM; ++d )
        {
            bounds[2 * d] = std::min( bounds[2 * d], *( center_it + d ) );
            bounds[2 * d + 1] =
                std::max( bounds[2 * d + 1], *( center_it + d ) );
        }
        center_it += DIM;
    }

    return CloudDomain<DIM>( bounds.getRawPtr() );
}

//---------------------------------------------------------------------------//

} // end namespace DataTransferKit

//---------------------------------------------------------------------------//

#endif // end DTK_CENTERDISTRIBUTOR_IMPL_HPP

//---------------------------------------------------------------------------//
// end DTK_CenterDistributor_impl.hpp
//---------------------------------------------------------------------------//