ENH: skip zero data sends via PstreamBuffers

- in several cases can use the PstreamBuffers recvDataCount(proci)
  on the receiving part of the logic

src/OpenFOAM/meshes/polyMesh/globalMeshData/globalPoints.C

@@ -487,6 +487,18 @@ void Foam::globalPoints::sendPatchPoints
     const polyBoundaryMesh& patches = mesh_.boundaryMesh();
     const labelPairList& patchInfo = globalTransforms_.patchTransformSign();
 
+    // Information to send:
+
+    // The patch face
+    DynamicList<label> patchFaces;
+
+    // Index in patch face
+    DynamicList<label> indexInFace;
+
+    // All information I currently hold about the patchPoint
+    DynamicList<labelPairList> allInfo;
+
+
     forAll(patches, patchi)
     {
         const polyPatch& pp = patches[patchi];
@@ -500,17 +512,17 @@ void Foam::globalPoints::sendPatchPoints
          && (mergeSeparated || patchInfo[patchi].first() == -1)
         )
         {
-            const processorPolyPatch& procPatch =
+            const auto& procPatch = refCast<const processorPolyPatch>(pp);
-                refCast<const processorPolyPatch>(pp);
+            const label nbrProci = procPatch.neighbProcNo();
 
-            // Information to send:
+            patchFaces.clear();
-            // patch face
+            patchFaces.reserve(pp.nPoints());
-            DynamicList<label> patchFaces(pp.nPoints());
-            // index in patch face
-            DynamicList<label> indexInFace(pp.nPoints());
-            // all information I currently hold about this patchPoint
-            DynamicList<labelPairList> allInfo(pp.nPoints());
 
+            indexInFace.clear();
+            indexInFace.reserve(pp.nPoints());
+
+            allInfo.clear();
+            allInfo.reserve(pp.nPoints());
 
             // Now collect information on all points mentioned in
             // changedPoints. Note that these points only should occur on
@@ -548,16 +560,20 @@ void Foam::globalPoints::sendPatchPoints
                 }
             }
 
-            // Send to neighbour
-            if (debug)
-            {
-                Pout<< " Sending from " << pp.name() << " to "
-                    << procPatch.neighbProcNo() << "   point information:"
-                    << patchFaces.size() << endl;
-            }
 
-            UOPstream toNeighbour(procPatch.neighbProcNo(), pBufs);
+            if (!patchFaces.empty())
-            toNeighbour << patchFaces << indexInFace << allInfo;
+            {
+                // Send to neighbour
+                if (debug)
+                {
+                    Pout<< " Sending from " << pp.name() << " to proc:"
+                        << nbrProci << " point information:"
+                        << patchFaces.size() << endl;
+                }
+
+                UOPstream toNeighbour(nbrProci, pBufs);
+                toNeighbour << patchFaces << indexInFace << allInfo;
+            }
         }
     }
 }
@@ -594,15 +610,20 @@ void Foam::globalPoints::receivePatchPoints
          && (mergeSeparated || patchInfo[patchi].first() == -1)
         )
         {
-            const processorPolyPatch& procPatch =
+            const auto& procPatch = refCast<const processorPolyPatch>(pp);
-                refCast<const processorPolyPatch>(pp);
+            const label nbrProci = procPatch.neighbProcNo();
+
+            if (!pBufs.recvDataCount(nbrProci))
+            {
+                continue;
+            }
 
             labelList patchFaces;
             labelList indexInFace;
             List<labelPairList> nbrInfo;
 
             {
-                UIPstream fromNeighbour(procPatch.neighbProcNo(), pBufs);
+                UIPstream fromNeighbour(nbrProci, pBufs);
                 fromNeighbour >> patchFaces >> indexInFace >> nbrInfo;
             }
 
@@ -610,7 +631,7 @@ void Foam::globalPoints::receivePatchPoints
             {
                 Pout<< " On " << pp.name()
                     << " Received from "
-                    << procPatch.neighbProcNo() << "   point information:"
+                    << nbrProci << "   point information:"
                     << patchFaces.size() << endl;
             }
 

src/OpenFOAM/meshes/polyMesh/syncTools/syncToolsTemplates.C

@@ -140,6 +140,8 @@ void Foam::syncTools::syncPointMap
                 const auto& procPatch = *ppp;
                 const label nbrProci = procPatch.neighbProcNo();
 
+                neighbProcs.append(nbrProci);
+
                 // Get data per patchPoint in neighbouring point numbers.
 
                 const labelList& meshPts = procPatch.meshPoints();
@@ -159,15 +161,18 @@ void Foam::syncTools::syncPointMap
                     }
                 }
 
-                neighbProcs.append(nbrProci);
+                if (!patchInfo.empty())
-                UOPstream toNbr(nbrProci, pBufs);
+                {
-                toNbr << patchInfo;
+                    UOPstream toNbr(nbrProci, pBufs);
+                    toNbr << patchInfo;
+                }
             }
         }
 
         // Limit exchange to involved procs
         pBufs.finishedNeighbourSends(neighbProcs);
 
+
         // Receive and combine.
         for (const polyPatch& pp : patches)
         {
@@ -178,8 +183,16 @@ void Foam::syncTools::syncPointMap
                 const auto& procPatch = *ppp;
                 const label nbrProci = procPatch.neighbProcNo();
 
-                UIPstream fromNbr(nbrProci, pBufs);
+                if (!pBufs.recvDataCount(nbrProci))
-                Map<T> nbrPatchInfo(fromNbr);
+                {
+                    continue;
+                }
+
+                Map<T> nbrPatchInfo(0);
+                {
+                    UIPstream fromNbr(nbrProci, pBufs);
+                    fromNbr >> nbrPatchInfo;
+                }
 
                 // Transform
                 top(procPatch, nbrPatchInfo);
@@ -383,6 +396,8 @@ void Foam::syncTools::syncEdgeMap
                 const auto& procPatch = *ppp;
                 const label nbrProci = procPatch.neighbProcNo();
 
+                neighbProcs.append(nbrProci);
+
                 // Get data per patch edge in neighbouring edge.
 
                 const edgeList& edges = procPatch.edges();
@@ -404,9 +419,11 @@ void Foam::syncTools::syncEdgeMap
                     }
                 }
 
-                neighbProcs.append(nbrProci);
+                if (!patchInfo.empty())
-                UOPstream toNbr(nbrProci, pBufs);
+                {
-                toNbr << patchInfo;
+                    UOPstream toNbr(nbrProci, pBufs);
+                    toNbr << patchInfo;
+                }
             }
         }
 
@@ -422,10 +439,16 @@ void Foam::syncTools::syncEdgeMap
             if (ppp && pp.nEdges())
             {
                 const auto& procPatch = *ppp;
+                const label nbrProci = procPatch.neighbProcNo();
 
-                EdgeMap<T> nbrPatchInfo;
+                if (!pBufs.recvDataCount(nbrProci))
                 {
-                    UIPstream fromNbr(procPatch.neighbProcNo(), pBufs);
+                    continue;
+                }
+
+                EdgeMap<T> nbrPatchInfo(0);
+                {
+                    UIPstream fromNbr(nbrProci, pBufs);
                     fromNbr >> nbrPatchInfo;
                 }
 
@@ -1115,6 +1138,8 @@ void Foam::syncTools::syncBoundaryFaceList
                     const auto& procPatch = *ppp;
                     const label nbrProci = procPatch.neighbProcNo();
 
+                    neighbProcs.append(nbrProci);
+
                     const SubList<T> fld
                     (
                         faceValues,
@@ -1122,7 +1147,6 @@ void Foam::syncTools::syncBoundaryFaceList
                         pp.start()-boundaryOffset
                     );
 
-                    neighbProcs.append(nbrProci);
                     UOPstream toNbr(nbrProci, pBufs);
                     toNbr << fld;
                 }
@@ -1140,11 +1164,13 @@ void Foam::syncTools::syncBoundaryFaceList
                 if (ppp && pp.size())
                 {
                     const auto& procPatch = *ppp;
+                    const label nbrProci = procPatch.neighbProcNo();
 
-                    List<T> recvFld(pp.size());
+                    List<T> recvFld;
-
+                    {
-                    UIPstream fromNbr(procPatch.neighbProcNo(), pBufs);
+                        UIPstream fromNbr(nbrProci, pBufs);
-                    fromNbr >> recvFld;
+                        fromNbr >> recvFld;
+                    }
 
                     top(procPatch, recvFld);
 

src/finiteArea/faMesh/faPatches/constraint/processor/processorFaPatch.C

@@ -318,8 +318,8 @@ void Foam::processorFaPatch::updateMesh(PstreamBuffers& pBufs)
 
     if (Pstream::parRun())
     {
-        labelList nbrPatchEdge(nPoints());
+        labelList nbrPatchEdge;
-        labelList nbrIndexInEdge(nPoints());
+        labelList nbrIndexInEdge;
 
         {
             // Note cannot predict exact size since edgeList not (yet) sent as

src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C

@@ -185,17 +185,13 @@ void Foam::fvMeshSubset::doCoupledPatches
             {
                 const label nbrProci = procPatch->neighbProcNo();
 
-                UOPstream toNeighbour(nbrProci, pBufs);
-
                 if (!nCellsUsingFace.empty())
                 {
+                    UOPstream toNeighbour(nbrProci, pBufs);
+
                     toNeighbour <<
                         SubList<label>(nCellsUsingFace, pp.size(), pp.start());
                 }
-                else
-                {
-                    toNeighbour << labelList();
-                }
             }
         }
 
@@ -210,6 +206,11 @@ void Foam::fvMeshSubset::doCoupledPatches
             {
                 const label nbrProci = procPatch->neighbProcNo();
 
+                if (!pBufs.recvDataCount(nbrProci))
+                {
+                    continue;
+                }
+
                 UIPstream fromNeighbour(nbrProci, pBufs);
 
                 const labelList nbrList(fromNeighbour);

src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/RecycleInteraction/RecycleInteraction.C

@@ -246,11 +246,13 @@ void Foam::RecycleInteraction<CloudType>::postEvolve()
 
         pBufs.finishedSends();
 
-        if (!returnReduceOr(pBufs.hasRecvData()))
+        // Not looping, so no early exit needed
-        {
+        //
-            // No parcels to recycle
+        // if (!returnReduceOr(pBufs.hasRecvData()))
-            return;
+        // {
-        }
+        //     // No parcels to recycle
+        //     return;
+        // }
 
         // Retrieve from receive buffers
         for (const int proci : pBufs.allProcs())

src/meshTools/AMIInterpolation/AMIInterpolation/advancingFrontAMI/advancingFrontAMIParallelOps.C

@@ -74,20 +74,28 @@ void Foam::advancingFrontAMI::distributePatches
     List<labelList>& faceIDs
 ) const
 {
+    faces.resize_nocopy(Pstream::nProcs());
+    points.resize_nocopy(Pstream::nProcs());
+    faceIDs.resize_nocopy(Pstream::nProcs());
+
+
     PstreamBuffers pBufs(Pstream::commsTypes::nonBlocking);
 
     for (const int domain : Pstream::allProcs())
     {
         const labelList& sendElems = map.subMap()[domain];
 
-        if (domain != Pstream::myProcNo() && sendElems.size())
+        if (sendElems.empty())
+        {
+            // Safety
+            faces[domain].clear();
+            points[domain].clear();
+            faceIDs[domain].clear();
+        }
+        else
         {
             faceList subFaces(UIndirectList<face>(pp, sendElems));
-            primitivePatch subPatch
+            primitivePatch subPatch(SubList<face>(subFaces), pp.points());
-            (
-                SubList<face>(subFaces),
-                pp.points()
-            );
 
             if (debug & 2)
             {
@@ -95,42 +103,28 @@ void Foam::advancingFrontAMI::distributePatches
                     << " sending faces " << subPatch.faceCentres() << endl;
             }
 
-            UOPstream toDomain(domain, pBufs);
+
-            toDomain
+            if (domain == Pstream::myProcNo())
-                << subPatch.localFaces() << subPatch.localPoints()
+            {
-                << gi.toGlobal(sendElems);
+                // Do send/receive for myself
+                faces[domain] = subPatch.localFaces();
+                points[domain] = subPatch.localPoints();
+                faceIDs[domain] = gi.toGlobal(sendElems);
+            }
+            else
+            {
+                // Normal send
+                UOPstream str(domain, pBufs);
+                str
+                    << subPatch.localFaces()
+                    << subPatch.localPoints()
+                    << gi.toGlobal(sendElems);
+            }
         }
     }
 
-    // Start receiving
     pBufs.finishedSends();
 
-    faces.setSize(Pstream::nProcs());
-    points.setSize(Pstream::nProcs());
-    faceIDs.setSize(Pstream::nProcs());
-
-    {
-        // Set up 'send' to myself
-        const labelList& sendElems = map.subMap()[Pstream::myProcNo()];
-        faceList subFaces(UIndirectList<face>(pp, sendElems));
-        primitivePatch subPatch
-        (
-            SubList<face>(subFaces),
-            pp.points()
-        );
-
-        // Receive
-        if (debug & 2)
-        {
-            Pout<< "distributePatches: to processor " << Pstream::myProcNo()
-                << " sending faces " << subPatch.faceCentres() << endl;
-        }
-
-        faces[Pstream::myProcNo()] = subPatch.localFaces();
-        points[Pstream::myProcNo()] = subPatch.localPoints();
-        faceIDs[Pstream::myProcNo()] = gi.toGlobal(sendElems);
-    }
-
     // Consume
     for (const int domain : Pstream::allProcs())
     {
@@ -138,9 +132,9 @@ void Foam::advancingFrontAMI::distributePatches
 
         if (domain != Pstream::myProcNo() && recvElems.size())
         {
-            UIPstream str(domain, pBufs);
+            UIPstream is(domain, pBufs);
 
-            str >> faces[domain]
+            is  >> faces[domain]
                 >> points[domain]
                 >> faceIDs[domain];
         }

src/meshTools/algorithms/MeshWave/FaceCellWave.C

@@ -537,6 +537,8 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
         const auto& procPatch =
             refCast<const processorPolyPatch>(mesh_.boundaryMesh()[patchi]);
 
+        const label nbrProci = procPatch.neighbProcNo();
+
         // Allocate buffers
         label nSendFaces;
         labelList sendFaces(procPatch.size());
@@ -561,45 +563,50 @@ void Foam::FaceCellWave<Type, TrackingData>::handleProcPatches()
             sendFacesInfo
         );
 
-        if (debug & 2)
+        if (nSendFaces)
         {
-            Pout<< " Processor patch " << patchi << ' ' << procPatch.name()
+            if (debug & 2)
-                << " communicating with " << procPatch.neighbProcNo()
+            {
-                << "  Sending:" << nSendFaces
+                Pout<< " Processor patch " << patchi << ' ' << procPatch.name()
-                << endl;
+                    << "  send:" << nSendFaces << " to proc:" << nbrProci
-        }
+                    << endl;
+            }
 
-        UOPstream toNeighbour(procPatch.neighbProcNo(), pBufs_);
+            UOPstream os(nbrProci, pBufs_);
-        //writeFaces(nSendFaces, sendFaces, sendFacesInfo, toNeighbour);
+            os
-        toNeighbour
+                << SubList<label>(sendFaces, nSendFaces)
-            << SubList<label>(sendFaces, nSendFaces)
+                << SubList<Type>(sendFacesInfo, nSendFaces);
-            << SubList<Type>(sendFacesInfo, nSendFaces);
+        }
     }
 
     // Finished sends
     pBufs_.finishedNeighbourSends(neighbourProcs);
 
-
     for (const label patchi : procPatches)
     {
         const auto& procPatch =
             refCast<const processorPolyPatch>(mesh_.boundaryMesh()[patchi]);
 
-        // Allocate buffers
+        const label nbrProci = procPatch.neighbProcNo();
+
+        if (!pBufs_.recvDataCount(nbrProci))
+        {
+            continue;
+        }
+
+
         labelList receiveFaces;
         List<Type> receiveFacesInfo;
-
         {
-            UIPstream fromNeighbour(procPatch.neighbProcNo(), pBufs_);
+            UIPstream is(nbrProci, pBufs_);
-            fromNeighbour >> receiveFaces >> receiveFacesInfo;
+            is >> receiveFaces >> receiveFacesInfo;
         }
 
         if (debug & 2)
         {
             Pout<< " Processor patch " << patchi << ' ' << procPatch.name()
-                << " communicating with " << procPatch.neighbProcNo()
+                << "  recv:" << receiveFaces.size() << " from proci:"
-                << "  Receiving:" << receiveFaces.size()
+                << nbrProci << endl;
-                << endl;
         }
 
         // Apply transform to received data for non-parallel planes

src/meshTools/algorithms/PointEdgeWave/PointEdgeWave.C

@@ -325,6 +325,8 @@ void Foam::PointEdgeWave<Type, TrackingData>::handleProcPatches()
         const auto& procPatch =
             refCast<const processorPolyPatch>(mesh_.boundaryMesh()[patchi]);
 
+        const label nbrProci = procPatch.neighbProcNo();
+
         patchInfo.clear();
         patchInfo.reserve(procPatch.nPoints());
         thisPoints.clear();
@@ -348,21 +350,25 @@ void Foam::PointEdgeWave<Type, TrackingData>::handleProcPatches()
         // Adapt for leaving domain
         leaveDomain(procPatch, thisPoints, patchInfo);
 
-        //if (debug)
+        if (patchInfo.size())
-        //{
+        {
-        //    Pout<< "Processor patch " << patchi << ' ' << procPatch.name()
+            //if (debug & 2)
-        //        << " communicating with " << procPatch.neighbProcNo()
+            //{
-        //        << "  Sending:" << patchInfo.size() << endl;
+            //    Pout<< "Processor patch " << patchi << ' ' << procPatch.name()
-        //}
+            //        << "  send:" << patchInfo.size()
+            //        << " to proc:" << nbrProci << endl;
+            //}
 
-        UOPstream toNeighbour(procPatch.neighbProcNo(), pBufs_);
+            UOPstream os(nbrProci, pBufs_);
-        toNeighbour << nbrPoints << patchInfo;
+            os << nbrPoints << patchInfo;
+        }
     }
 
 
     // Finished sends
     pBufs_.finishedNeighbourSends(neighbourProcs);
 
+
     //
     // 2. Receive all point info on processor patches.
     //
@@ -372,19 +378,25 @@ void Foam::PointEdgeWave<Type, TrackingData>::handleProcPatches()
         const auto& procPatch =
             refCast<const processorPolyPatch>(mesh_.boundaryMesh()[patchi]);
 
-        List<Type> patchInfo;
+        const label nbrProci = procPatch.neighbProcNo();
-        labelList patchPoints;
 
+        if (!pBufs_.recvDataCount(nbrProci))
         {
-            UIPstream fromNeighbour(procPatch.neighbProcNo(), pBufs_);
+            continue;
-            fromNeighbour >> patchPoints >> patchInfo;
         }
 
-        //if (debug)
+        labelList patchPoints;
+        List<Type> patchInfo;
+        {
+            UIPstream is(nbrProci, pBufs_);
+            is >> patchPoints >> patchInfo;
+        }
+
+        //if (debug & 2)
         //{
         //    Pout<< "Processor patch " << patchi << ' ' << procPatch.name()
-        //        << " communicating with " << procPatch.neighbProcNo()
+        //        << "  recv:" << patchInfo.size() << " from proc:"
-        //        << "  Received:" << patchInfo.size() << endl;
+        //        << nbrProci << endl;
         //}
 
         // Apply transform to received data for non-parallel planes

src/meshTools/processorLOD/box/box.C

@@ -110,7 +110,7 @@ void Foam::processorLODs::box::setRefineFlags
     // Identify src boxes that can be refined and send to all remote procs
     for (const int proci : Pstream::allProcs())
     {
-        if (proci != Pstream::myProcNo())
+        if (proci != Pstream::myProcNo() && !boxes_[proci].empty())
         {
             UOPstream toProc(proci, pBufs);
             toProc << nObjectsOfType_ << boxes_[proci] << newToOld_[proci];
@@ -123,10 +123,8 @@ void Foam::processorLODs::box::setRefineFlags
     // src boxes can/should be refined
     for (const int proci : Pstream::allProcs())
     {
-        if (proci == Pstream::myProcNo())
+        if (proci == Pstream::myProcNo() || !pBufs.recvDataCount(proci))
         {
-            // Not refining boxes I send to myself - will be sending all local
-            // elements
             continue;
         }
 

src/overset/cellCellStencil/inverseDistance/inverseDistanceCellCellStencil.C

@@ -355,27 +355,26 @@ void Foam::cellCellStencils::inverseDistance::markPatchesAsHoles
     {
         if (procI != Pstream::myProcNo())
         {
-            //const treeBoundBox& srcBb = srcBbs[procI];
             const treeBoundBox& srcPatchBb = srcPatchBbs[procI];
             const treeBoundBox& tgtPatchBb = tgtPatchBbs[Pstream::myProcNo()];
 
             if (srcPatchBb.overlaps(tgtPatchBb))
             {
                 UIPstream is(procI, pBufs);
-                {
+                const treeBoundBox receivedBb(is);
-                    treeBoundBox receivedBb(is);
-                    if (srcPatchBb != receivedBb)
-                    {
-                        FatalErrorInFunction
-                            << "proc:" << procI
-                            << " srcPatchBb:" << srcPatchBb
-                            << " receivedBb:" << receivedBb
-                            << exit(FatalError);
-                    }
-                }
                 const labelVector zoneDivs(is);
                 const PackedList<2> srcPatchTypes(is);
 
+                // Verify validity
+                if (srcPatchBb != receivedBb)
+                {
+                    FatalErrorInFunction
+                        << "proc:" << procI
+                        << " srcPatchBb:" << srcPatchBb
+                        << " receivedBb:" << receivedBb
+                        << exit(FatalError);
+                }
+
                 forAll(tgtCellMap, tgtCelli)
                 {
                     label celli = tgtCellMap[tgtCelli];

src/overset/cellCellStencil/trackingInverseDistance/trackingInverseDistanceCellCellStencil.C

@@ -273,20 +273,20 @@ void Foam::cellCellStencils::trackingInverseDistance::markPatchesAsHoles
             if (srcPatchBb.overlaps(tgtPatchBb))
             {
                 UIPstream is(procI, pBufs);
-                {
+                const treeBoundBox receivedBb(is);
-                    treeBoundBox receivedBb(is);
-                    if (srcPatchBb != receivedBb)
-                    {
-                        FatalErrorInFunction
-                            << "proc:" << procI
-                            << " srcPatchBb:" << srcPatchBb
-                            << " receivedBb:" << receivedBb
-                            << exit(FatalError);
-                    }
-                }
                 const labelVector srcDivs(is);
                 const PackedList<2> srcPatchTypes(is);
 
+                // Verify validity
+                if (srcPatchBb != receivedBb)
+                {
+                    FatalErrorInFunction
+                        << "proc:" << procI
+                        << " srcPatchBb:" << srcPatchBb
+                        << " receivedBb:" << receivedBb
+                        << exit(FatalError);
+                }
+
                 forAll(tgtCellMap, tgtCelli)
                 {
                     label celli = tgtCellMap[tgtCelli];