From 02bf8928cbe1e8d96b98beab2f9572593266c922 Mon Sep 17 00:00:00 2001
From: Mark Olesen <Mark.Olesen@esi-group.com>
Date: Wed, 12 May 2021 22:55:57 +0200
Subject: [PATCH] ENH: faMeshReconstructor for reconstructing equivalent serial
 faMesh (#2084)

- A bare-bones reconstructor for finiteArea meshes when processor
  meshes are available (in parallel) but an equivalent serial faMesh
  is needed for reconstruction or decomposition.
  In these situations, a serial version of the faMesh is needed,
  but preferably without reconstructing the entire volume mesh.

  It uses the finiteVolume faceProcAddressing in addition to
  the geometric information available from the underlying polyMesh.

  The resulting equivalent faMesh can be used for basic operations,
  but caution should be exercised before attempting large operations.
---
 .../reconstruct/faReconstruct/Make/files      |   1 +
 .../faReconstruct/faMeshReconstructor.C       | 637 ++++++++++++++++++
 .../faReconstruct/faMeshReconstructor.H       | 222 ++++++
 3 files changed, 860 insertions(+)
 create mode 100644 src/parallel/reconstruct/faReconstruct/faMeshReconstructor.C
 create mode 100644 src/parallel/reconstruct/faReconstruct/faMeshReconstructor.H

diff --git a/src/parallel/reconstruct/faReconstruct/Make/files b/src/parallel/reconstruct/faReconstruct/Make/files
index 4d7028d13c..c0f15e7ecd 100644
--- a/src/parallel/reconstruct/faReconstruct/Make/files
+++ b/src/parallel/reconstruct/faReconstruct/Make/files
@@ -1,4 +1,5 @@
 processorFaMeshes.C
 faFieldReconstructor.C
+faMeshReconstructor.C
 
 LIB = $(FOAM_LIBBIN)/libfaReconstruct
diff --git a/src/parallel/reconstruct/faReconstruct/faMeshReconstructor.C b/src/parallel/reconstruct/faReconstruct/faMeshReconstructor.C
new file mode 100644
index 0000000000..0f85a81d5e
--- /dev/null
+++ b/src/parallel/reconstruct/faReconstruct/faMeshReconstructor.C
@@ -0,0 +1,637 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2021 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+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
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "faMeshReconstructor.H"
+#include "globalIndex.H"
+#include "globalMeshData.H"
+#include "edgeHashes.H"
+#include "Time.H"
+#include "PstreamCombineReduceOps.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+int Foam::faMeshReconstructor::debug = 0;
+
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+void Foam::faMeshReconstructor::calcAddressing
+(
+    const labelUList& fvFaceProcAddr
+)
+{
+    const globalIndex globalFaceNum(procMesh_.nFaces());
+
+    // ----------------------
+    // boundaryProcAddressing
+    //
+    // Trivial since non-processor boundary ordering is identical
+
+    const label nPatches = procMesh_.boundary().size();
+
+    faBoundaryProcAddr_ = identity(nPatches);
+
+    // Mark processor patches
+    for
+    (
+        label patchi = procMesh_.boundary().nNonProcessor();
+        patchi < nPatches;
+        ++patchi
+    )
+    {
+        faBoundaryProcAddr_[patchi] = -1;
+    }
+
+
+    // ------------------
+    // faceProcAddressing
+    //
+    // Transcribe/rewrite based on finiteVolume faceProcAddressing
+
+    faFaceProcAddr_ = procMesh_.faceLabels();
+
+    // From local faceLabels to proc values
+    for (label& facei : faFaceProcAddr_)
+    {
+        // Use finiteVolume info, ignoring face flips
+        facei = mag(fvFaceProcAddr[facei] - 1);
+    }
+
+
+    // Make global consistent.
+    // Starting at '0', without gaps in numbering etc.
+    // - the sorted order is the obvious solution
+    {
+        globalFaceNum.gather(faFaceProcAddr_, singlePatchFaceLabels_);
+
+        labelList order(Foam::sortedOrder(singlePatchFaceLabels_));
+
+        singlePatchFaceLabels_ = labelList(singlePatchFaceLabels_, order);
+
+        globalFaceNum.scatter(order, faFaceProcAddr_);
+    }
+
+    // Broadcast the same information everywhere
+    Pstream::scatter(singlePatchFaceLabels_);
+
+
+    // ------------------
+    // edgeProcAddressing
+    //
+    // This is more complicated.
+
+    // Create a single (serial) patch of the finiteArea mesh without a
+    // corresponding volume mesh, otherwise it would be the same as
+    // reconstructPar on the volume mesh (big, slow, etc).
+    //
+    // Do manual point-merge and relabeling to avoid dependency on
+    // finiteVolume pointProcAddressing
+
+    faPointProcAddr_.clear();  // Final size == procMesh_.nPoints()
+
+    // 1.
+    // - Topological point merge of the area meshes
+    // - use the local patch faces and points
+
+    // 2.
+    // - build a single (serial) patch of the finiteArea mesh only
+    //   without any point support from the volume mesh
+    // - it may be possible to skip this step, but not obvious how
+
+    // The collected faces are contiguous per processor, which gives us
+    // the possibility to easily identify their source by using the
+    // global face indexing (if needed).
+    // The ultimate face locations are handled with a separate ordering
+    // list.
+
+    const uindirectPrimitivePatch& procPatch = procMesh_.patch();
+
+
+    {
+        faceList singlePatchProcFaces;  // [proc0faces, proc1faces ...]
+        labelList uniqueMeshPointLabels;
+
+        // Local face points to compact merged point index
+        labelList pointToGlobal;
+
+        autoPtr<globalIndex> globalPointsPtr =
+            procMesh_.mesh().globalData().mergePoints
+            (
+                procPatch.meshPoints(),
+                procPatch.meshPointMap(),  // unused
+                pointToGlobal,
+                uniqueMeshPointLabels
+            );
+
+        // Gather faces, renumbered for the *merged* points
+        faceList tmpFaces(globalFaceNum.localSize());
+
+        forAll(tmpFaces, facei)
+        {
+            tmpFaces[facei] =
+                face(pointToGlobal, procPatch.localFaces()[facei]);
+        }
+
+        globalFaceNum.gather
+        (
+            tmpFaces,
+            singlePatchProcFaces,
+            UPstream::msgType(),
+            Pstream::commsTypes::scheduled
+        );
+
+        globalPointsPtr().gather
+        (
+            UIndirectList<point>
+            (
+                procPatch.points(),  // NB: mesh points (non-local)
+                uniqueMeshPointLabels
+            ),
+            singlePatchPoints_
+        );
+
+        // Transcribe into final assembled order
+        singlePatchFaces_.resize(singlePatchProcFaces.size());
+
+        // Target face ordering
+        labelList singlePatchProcAddr;
+        globalFaceNum.gather(faFaceProcAddr_, singlePatchProcAddr);
+
+        forAll(singlePatchProcAddr, facei)
+        {
+            const label targetFacei = singlePatchProcAddr[facei];
+            singlePatchFaces_[targetFacei] = singlePatchProcFaces[facei];
+        }
+
+        // Use initial equivalent "global" (serial) patch
+        // to establish the correct point and face walking order
+        //
+        // - only meaningful on master
+        const primitivePatch initialPatch
+        (
+            SubList<face>(singlePatchFaces_),
+            singlePatchPoints_
+        );
+
+        // Grab the faces/points in local point ordering
+        tmpFaces = initialPatch.localFaces();
+        pointField tmpPoints(initialPatch.localPoints());
+
+        // The meshPointMap is contiguous, so flatten as linear list
+        /// Map<label> mpm(initialPatch.meshPointMap());
+        labelList mpm(initialPatch.nPoints());
+        forAllConstIters(initialPatch.meshPointMap(), iter)
+        {
+            mpm[iter.key()] = iter.val();
+        }
+        Pstream::scatter(mpm);
+
+        // Rewrite pointToGlobal according to the correct point order
+        for (label& pointi : pointToGlobal)
+        {
+            pointi = mpm[pointi];
+        }
+
+        // Finalize. overwrite
+        faPointProcAddr_ = std::move(pointToGlobal);
+
+        singlePatchFaces_ = std::move(tmpFaces);
+        singlePatchPoints_ = std::move(tmpPoints);
+    }
+
+    // Broadcast the same information everywhere
+    Pstream::scatter(singlePatchFaces_);
+    Pstream::scatter(singlePatchPoints_);
+
+    // Now have enough global information to determine global edge mappings
+
+    // Equivalent "global" (serial) patch
+    const primitivePatch onePatch
+    (
+        SubList<face>(singlePatchFaces_),
+        singlePatchPoints_
+    );
+
+    faEdgeProcAddr_.clear();
+    faEdgeProcAddr_.resize(procMesh_.nEdges(), -1);
+
+    {
+        EdgeMap<label> globalEdgeMapping(2*onePatch.nEdges());
+
+        // Pass 1: edge-hash lookup with edges in "natural" patch order
+
+        // Can use local edges() directly without remap via meshPoints()
+        // since the previous sorting means that we are already working
+        // with faces that are in the local point order and even
+        // the points themselves are also in the local point order
+        for (const edge& e : onePatch.edges())
+        {
+            globalEdgeMapping.insert(e, globalEdgeMapping.size());
+        }
+
+        // Lookup proc local edges (in natural order) to global equivalent
+        for (label edgei = 0; edgei < procPatch.nEdges(); ++edgei)
+        {
+            const edge globalEdge(faPointProcAddr_, procPatch.edges()[edgei]);
+
+            const auto fnd = globalEdgeMapping.cfind(globalEdge);
+
+            if (fnd.found())
+            {
+                faEdgeProcAddr_[edgei] = fnd.val();
+            }
+            else
+            {
+                FatalErrorInFunction
+                    << "Failed to find edge " << globalEdge
+                    << " this indicates a programming error" << nl
+                    << exit(FatalError);
+            }
+        }
+    }
+
+    // Now have consistent global edge
+    // This of course would all be too easy.
+    // The finiteArea edge lists have been defined as their own sorted
+    // order with sublists etc.
+
+    // Gather edge ids for nonProcessor boundaries.
+    // These will also be in the serial geometry
+
+    Map<label> remapGlobal(2*onePatch.nEdges());
+    for (label edgei = 0; edgei < onePatch.nInternalEdges(); ++edgei)
+    {
+        remapGlobal.insert(edgei, remapGlobal.size());
+    }
+
+    //
+    singlePatchEdgeLabels_.clear();
+    singlePatchEdgeLabels_.resize(procMesh_.boundary().nNonProcessor());
+
+    forAll(singlePatchEdgeLabels_, patchi)
+    {
+        const faPatch& fap = procMesh_.boundary()[patchi];
+
+        labelList& patchEdgeLabels = singlePatchEdgeLabels_[patchi];
+        patchEdgeLabels = fap.edgeLabels();
+
+        // Renumber from local edges to global edges (natural order)
+        for (label& edgeId : patchEdgeLabels)
+        {
+            edgeId = faEdgeProcAddr_[edgeId];
+        }
+
+        // OR patchEdgeLabels =
+        // UIndirectList<label>(faEdgeProcAddr_, fap.edgeLabels());
+
+
+        // Collect from all processors
+        combineReduce
+        (
+            patchEdgeLabels,
+            ListOps::appendEqOp<label>()
+        );
+
+        // Sorted order will be the original non-decomposed order
+        Foam::sort(patchEdgeLabels);
+
+        for (const label sortedEdgei : patchEdgeLabels)
+        {
+            remapGlobal.insert(sortedEdgei, remapGlobal.size());
+        }
+    }
+
+    {
+        // Use the map to rewrite the local faEdgeProcAddr_
+
+        labelList newEdgeProcAddr(faEdgeProcAddr_);
+
+        label edgei = procMesh_.nInternalEdges();
+
+        for (const faPatch& fap : procMesh_.boundary())
+        {
+            for (const label patchEdgei : fap.edgeLabels())
+            {
+                const label globalEdgei = faEdgeProcAddr_[patchEdgei];
+
+                const auto fnd = remapGlobal.cfind(globalEdgei);
+                if (fnd.found())
+                {
+                    newEdgeProcAddr[edgei] = fnd.val();
+                    ++edgei;
+                }
+                else
+                {
+                    FatalErrorInFunction
+                        << "Failed to find edge " << globalEdgei
+                        << " this indicates a programming error" << nl
+                        << exit(FatalError);
+                }
+            }
+        }
+
+        faEdgeProcAddr_ = std::move(newEdgeProcAddr);
+    }
+}
+
+
+void Foam::faMeshReconstructor::initPatch() const
+{
+    serialPatchPtr_.reset
+    (
+        new primitivePatch
+        (
+            SubList<face>(singlePatchFaces_),
+            singlePatchPoints_
+        )
+    );
+}
+
+
+void Foam::faMeshReconstructor::createMesh()
+{
+    const Time& runTime = procMesh_.mesh().time();
+
+    // Time for non-parallel case (w/o functionObjects or libs)
+    serialRunTime_ = Time::New(runTime.globalPath().toAbsolute());
+
+
+    // Trivial polyMesh only containing points and faces.
+    // This is valid, provided we don't use it for anything complicated.
+
+    serialVolMesh_.reset
+    (
+        new polyMesh
+        (
+            IOobject
+            (
+                procMesh_.mesh().name(),  // Volume region name
+                procMesh_.mesh().facesInstance(),
+
+                *serialRunTime_,
+
+                IOobject::NO_READ,
+                IOobject::NO_WRITE,
+                false  // not registered
+            ),
+            pointField(singlePatchPoints_),  // copy
+            faceList(singlePatchFaces_),     // copy
+            labelList(singlePatchFaces_.size(), Zero),  // faceOwner
+            labelList(),  // faceNeighbour
+            false  // no syncPar!
+        )
+    );
+
+    // A simple area-mesh with one-to-one mapping of faceLabels
+    serialAreaMesh_.reset
+    (
+        new faMesh
+        (
+            *serialVolMesh_,
+            identity(singlePatchFaces_.size())  // faceLabels
+        )
+    );
+
+    auto& completeMesh = *serialAreaMesh_;
+
+    // Add in non-processor boundary patches
+    PtrList<faPatch> completePatches(singlePatchEdgeLabels_.size());
+    forAll(completePatches, patchi)
+    {
+        const labelList& patchEdgeLabels = singlePatchEdgeLabels_[patchi];
+
+        const faPatch& fap = procMesh_.boundary()[patchi];
+
+        const label neiPolyPatchId = fap.ngbPolyPatchIndex();
+
+        completePatches.set
+        (
+            patchi,
+            fap.clone
+            (
+                completeMesh.boundary(),
+                patchEdgeLabels,
+                patchi,  // index
+                neiPolyPatchId
+            )
+        );
+    }
+
+    completeMesh.addFaPatches(completePatches);
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::faMeshReconstructor::faMeshReconstructor
+(
+    const faMesh& procMesh
+)
+:
+    procMesh_(procMesh)
+{
+    if (!Pstream::parRun())
+    {
+        FatalErrorInFunction
+            << "Can only be called in parallel!!" << nl
+            << exit(FatalError);
+    }
+
+    // Require faceProcAddressing from finiteVolume decomposition
+    labelIOList fvFaceProcAddressing
+    (
+        IOobject
+        (
+            "faceProcAddressing",
+            procMesh_.mesh().facesInstance(),
+
+            // Or search?
+            // procMesh_.time().findInstance
+            // (
+            //     // Search for polyMesh face instance
+            //     // mesh.facesInstance()
+            //     procMesh_.mesh().meshDir(),
+            //     "faceProcAddressing"
+            // ),
+
+            polyMesh::meshSubDir,
+            procMesh_.mesh(),    // The polyMesh db
+            IOobject::MUST_READ,
+            IOobject::NO_WRITE,
+            false  // not registered
+        )
+    );
+
+    calcAddressing(fvFaceProcAddressing);
+}
+
+
+Foam::faMeshReconstructor::faMeshReconstructor
+(
+    const faMesh& procMesh,
+    const labelUList& fvFaceProcAddressing
+)
+:
+    procMesh_(procMesh)
+{
+    if (!Pstream::parRun())
+    {
+        FatalErrorInFunction
+            << "Can only be called in parallel!!" << nl
+            << exit(FatalError);
+    }
+
+    calcAddressing(fvFaceProcAddressing);
+}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+Foam::faMeshReconstructor::~faMeshReconstructor()
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+void Foam::faMeshReconstructor::clearGeom()
+{
+    serialAreaMesh_.reset(nullptr);
+    serialVolMesh_.reset(nullptr);
+    serialRunTime_.reset(nullptr);
+}
+
+
+const Foam::primitivePatch& Foam::faMeshReconstructor::patch() const
+{
+    if (!serialPatchPtr_)
+    {
+        initPatch();
+    }
+
+    return *serialPatchPtr_;
+}
+
+
+Foam::primitivePatch& Foam::faMeshReconstructor::patch()
+{
+    if (!serialPatchPtr_)
+    {
+        initPatch();
+    }
+
+    return *serialPatchPtr_;
+}
+
+
+const Foam::faMesh& Foam::faMeshReconstructor::mesh() const
+{
+    if (!serialAreaMesh_)
+    {
+        const_cast<faMeshReconstructor&>(*this).createMesh();
+    }
+
+    return *serialAreaMesh_;
+}
+
+
+void Foam::faMeshReconstructor::writeAddressing() const
+{
+    writeAddressing(procMesh_.mesh().facesInstance());
+}
+
+
+void Foam::faMeshReconstructor::writeAddressing(const word& timeName) const
+{
+    // Write copies
+
+    IOobject ioAddr
+    (
+        "procAddressing",
+        timeName,
+        faMesh::meshSubDir,
+        procMesh_.mesh(),  // The polyMesh
+        IOobject::NO_READ,
+        IOobject::NO_WRITE,
+        false  // not registered
+    );
+
+    // boundaryProcAddressing
+    ioAddr.rename("boundaryProcAddressing");
+    labelIOList(ioAddr, faBoundaryProcAddr_).write();
+
+    // faceProcAddressing
+    ioAddr.rename("faceProcAddressing");
+    labelIOList(ioAddr, faFaceProcAddr_).write();
+
+    // pointProcAddressing
+    ioAddr.rename("pointProcAddressing");
+    labelIOList(ioAddr, faPointProcAddr_).write();
+
+    // edgeProcAddressing
+    ioAddr.rename("edgeProcAddressing");
+    labelIOList(ioAddr, faEdgeProcAddr_).write();
+}
+
+
+void Foam::faMeshReconstructor::writeMesh() const
+{
+    writeMesh(procMesh_.mesh().facesInstance());
+}
+
+
+void Foam::faMeshReconstructor::writeMesh(const word& timeName) const
+{
+    const faMesh& fullMesh = this->mesh();
+
+    const bool oldDistributed = fileHandler().distributed();
+    auto oldHandler = fileHandler(fileOperation::NewUncollated());
+    fileHandler().distributed(true);
+
+    if (Pstream::master())
+    {
+        const bool oldParRun = Pstream::parRun(false);
+
+        IOobject io(fullMesh.boundary());
+
+        io.rename("faceLabels");
+        labelIOList(io, singlePatchFaceLabels_).write();
+
+        fullMesh.boundary().write();
+
+        Pstream::parRun(oldParRun);
+    }
+
+    // Restore old settings
+    if (oldHandler)
+    {
+        fileHandler(std::move(oldHandler));
+    }
+    fileHandler().distributed(oldDistributed);
+}
+
+
+// ************************************************************************* //
diff --git a/src/parallel/reconstruct/faReconstruct/faMeshReconstructor.H b/src/parallel/reconstruct/faReconstruct/faMeshReconstructor.H
new file mode 100644
index 0000000000..8cf5154f44
--- /dev/null
+++ b/src/parallel/reconstruct/faReconstruct/faMeshReconstructor.H
@@ -0,0 +1,222 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2021 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+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
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::faMeshReconstructor
+
+Description
+    A bare-bones reconstructor for finiteArea meshes when processor
+    meshes are available (in parallel) but an equivalent serial faMesh
+    is needed for reconstruction or decomposition.
+    In these situations, a serial version of the faMesh is needed,
+    but preferably without reconstructing the entire volume mesh.
+
+    It uses the finiteVolume faceProcAddressing in addition to
+    the geometric information available from the underlying polyMesh.
+
+    The resulting equivalent faMesh can be used for basic operations,
+    but caution should be exercised before attempting large operations.
+
+SourceFiles
+    faMeshReconstructor.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef faMeshReconstructor_H
+#define faMeshReconstructor_H
+
+#include "faMesh.H"
+#include "primitivePatch.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// Forward Declarations
+class Time;
+
+/*---------------------------------------------------------------------------*\
+                     Class faMeshReconstructor Declaration
+\*---------------------------------------------------------------------------*/
+
+class faMeshReconstructor
+{
+    // Private Data
+
+        //- The processor-specific faMesh
+        const faMesh& procMesh_;
+
+
+    // Addressing
+
+        //- Processor face addressing, derived from finite volume information
+        labelList faFaceProcAddr_;
+
+        //- Processor boundary addressing
+        labelList faBoundaryProcAddr_;
+
+        //- Processor point addressing
+        labelList faPointProcAddr_;
+
+        //- Processor edge addressing
+        labelList faEdgeProcAddr_;
+
+
+    // Equivalent surface information
+
+        //- Faces labels for a single patch
+        labelList singlePatchFaceLabels_;
+
+        //- Faces for a single patch
+        faceList singlePatchFaces_;
+
+        //- Support points for a single patch
+        pointField singlePatchPoints_;
+
+        //- Lists of edge-labels (per edge patch) for the single patch
+        labelListList singlePatchEdgeLabels_;
+
+
+    // Demand-driven data
+
+        //- Primitive patch
+        mutable autoPtr<primitivePatch> serialPatchPtr_;
+
+        //- Time database for serial meshes
+        autoPtr<Time> serialRunTime_;
+
+        //- Dummy volume mesh, used for serial area mesh
+        autoPtr<polyMesh> serialVolMesh_;
+
+        //- Equivalent serial area mesh
+        autoPtr<faMesh> serialAreaMesh_;
+
+
+    // Private Member Functions
+
+        //- Calculate all addressing, using finiteVolume faceProcAddressing
+        void calcAddressing(const labelUList& fvFaceProcAddr);
+
+        //- Set primitive patch, removing any old one
+        void initPatch() const;
+
+        //- Create the serial geometry
+        void createMesh();
+
+        //- No copy construct
+        faMeshReconstructor(const faMeshReconstructor&) = delete;
+
+        //- No copy assignment
+        void operator=(const faMeshReconstructor&) = delete;
+
+
+public:
+
+    //- Debug flag
+    static int debug;
+
+
+    // Constructors
+
+        //- Construct from components
+        explicit faMeshReconstructor(const faMesh& procMesh);
+
+        //- Construct from components
+        faMeshReconstructor
+        (
+            const faMesh& procMesh,
+            const labelUList& fvFaceProcAddressing
+        );
+
+
+    //- Destructor
+    ~faMeshReconstructor();
+
+        void clearGeom();
+
+
+    // Member Functions
+
+        //- Processor point addressing
+        const labelList& pointProcAddressing() const noexcept
+        {
+            return faPointProcAddr_;
+        }
+
+        //- Processor edge addressing
+        const labelList& edgeProcAddressing() const noexcept
+        {
+            return faEdgeProcAddr_;
+        }
+
+        //- Processor face addressing
+        const labelList& faceProcAddressing() const noexcept
+        {
+            return faFaceProcAddr_;
+        }
+
+        //- Processor boundary addressing
+        const labelList& boundaryProcAddressing() const noexcept
+        {
+            return faBoundaryProcAddr_;
+        }
+
+
+        //- Serial equivalent patch
+        const primitivePatch& patch() const;
+
+        //- Serial equivalent patch
+        primitivePatch& patch();
+
+        //- Serial equivalent faMesh
+        const faMesh& mesh() const;
+
+
+    // Write
+
+        //- Write proc addressing at the polyMesh faceInstances time
+        void writeAddressing() const;
+
+        //- Write proc addressing at the given time
+        void writeAddressing(const word& timeName) const;
+
+        //- Write equivalent mesh information at the polyMesh faceInstances time
+        void writeMesh() const;
+
+        //- Write equivalent mesh information at the given time
+        void writeMesh(const word& timeName) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //