scotchDecomp.H

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/*---------------------------------------------------------------------------*\
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License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
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Class
    Foam::scotchDecomp

Description
    Scotch domain decomposition

SourceFiles
    scotchDecomp.C

\*---------------------------------------------------------------------------*/

#ifndef scotchDecomp_H
#define scotchDecomp_H

#include <decompositionMethods/decompositionMethod.H>

namespace Foam
{

/*---------------------------------------------------------------------------*\
                           Class scotchDecomp Declaration
\*---------------------------------------------------------------------------*/

class scotchDecomp
:
    public decompositionMethod
{
    // Private data

        const polyMesh& mesh_;


    // Private Member Functions

        //- Check and print error message
        static void check(const int, const char*);

        label decompose
        (
            const List<int>& adjncy,
            const List<int>& xadj,
            const scalarField& cWeights,
            List<int>& finalDecomp
        );

        //- Disallow default bitwise copy construct and assignment
        void operator=(const scotchDecomp&);
        scotchDecomp(const scotchDecomp&);


public:

    //- Runtime type information
    TypeName("scotch");


    // Constructors

        //- Construct given the decomposition dictionary and mesh
        scotchDecomp
        (
            const dictionary& decompositionDict,
            const polyMesh& mesh
        );


    // Destructor

        virtual ~scotchDecomp()
        {}


    // Member Functions

        virtual bool parallelAware() const
        {
            // Metis does not know about proc boundaries
            return false;
        }

        //- Return for every coordinate the wanted processor number. Use the
        //  mesh connectivity (if needed)
        //  Weights get normalised so the minimum value is 1 before truncation
        //  to an integer so the weights should be multiples of the minimum
        //  value. The overall sum of weights might otherwise overflow.
        virtual labelList decompose
        (
            const pointField& points,
            const scalarField& pointWeights
        );

        //- Return for every coordinate the wanted processor number. Gets
        //  passed agglomeration map (from fine to coarse cells) and coarse cell
        //  location. Can be overridden by decomposers that provide this
        //  functionality natively.
        //  See note on weights above.
        virtual labelList decompose
        (
            const labelList& agglom,
            const pointField& regionPoints,
            const scalarField& regionWeights
        );

        //- Same but with uniform weights
        virtual labelList decompose
        (
            const labelList& agglom,
            const pointField& regionPoints
        )
        {
            return decompose
            (
                agglom,
                regionPoints,
                scalarField(regionPoints.size(), 1.0)
            );
        }

        //- Return for every coordinate the wanted processor number. Explicitly
        //  provided mesh connectivity.
        //  The connectivity is equal to mesh.cellCells() except for
        //  - in parallel the cell numbers are global cell numbers (starting
        //    from 0 at processor0 and then incrementing all through the
        //    processors)
        //  - the connections are across coupled patches
        //  See note on weights above.
        virtual labelList decompose
        (
            const labelListList& globalCellCells,
            const pointField& cc,
            const scalarField& cWeights
        );


        //- Helper to convert local connectivity (supplied as owner,neighbour)
        //  into CSR (Metis,scotch) storage. Does cyclics but not processor
        //  patches
        static void calcCSR
        (
            const polyMesh& mesh,
            List<int>& adjncy,
            List<int>& xadj
        );

        //- Helper to convert connectivity (supplied as cellcells) into
        //  CSR (Metis,scotch) storage
        static void calcCSR
        (
            const labelListList& globalCellCells,
            List<int>& adjncy,
            List<int>& xadj
        );
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

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