From e92975075af2f7eb5e9d1aae8d4b7f5f5eee8ae9 Mon Sep 17 00:00:00 2001
From: Mark Olesen <Mark.Olesen@esi-group.com>
Date: Mon, 12 Jun 2023 15:21:20 +0200
Subject: [PATCH] ENH: sum reduction of nPoints/nFaces/nCells in a single call
 (globalMeshData)

STYLE: use labelRange instead of identity(...) for communicator
---
 .../procFacesGAMGProcAgglomeration.C          |  3 +-
 .../polyMesh/globalMeshData/globalMeshData.C  | 50 +++++--------------
 .../polyMesh/globalMeshData/globalMeshData.H  | 14 +++---
 3 files changed, 21 insertions(+), 46 deletions(-)

diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
index d537dae584..52baecc75b 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
@@ -152,7 +152,7 @@ Foam::procFacesGAMGProcAgglomeration::processorAgglomeration
     UPstream::communicator singleCellMeshComm
     (
         mesh.comm(),
-        labelList(Foam::one{}, 0)   // only processor 0
+        labelRange(1)  // Processor 0 only
     );
 
     scalarField faceWeights;
@@ -197,7 +197,6 @@ Foam::procFacesGAMGProcAgglomeration::processorAgglomeration
     }
 
     Pstream::broadcast(fineToCoarse, mesh.comm());
-    singleCellMeshComm.reset();
 
     return tfineToCoarse;
 }
diff --git a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C
index feba605416..7fd3cb883b 100644
--- a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C
+++ b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C
@@ -2504,8 +2504,8 @@ Foam::autoPtr<Foam::globalIndex> Foam::globalMeshData::mergePoints
     const globalIndex globalPPoints(meshPoints.size());
 
     labelList patchToCoupled(meshPoints.size(), -1);
-    label nCoupled = 0;
     labelList coupledToGlobalPatch(pointSlavesMap.constructSize(), -1);
+    //label nCoupled = 0;
 
     // Note: loop over patch since usually smaller
     forAll(meshPoints, patchPointi)
@@ -2518,7 +2518,7 @@ Foam::autoPtr<Foam::globalIndex> Foam::globalMeshData::mergePoints
         {
             patchToCoupled[patchPointi] = iter();
             coupledToGlobalPatch[iter()] = globalPPoints.toGlobal(patchPointi);
-            nCoupled++;
+            //++nCoupled;
         }
     }
 
@@ -2718,55 +2718,31 @@ void Foam::globalMeshData::updateMesh()
     UPstream::communicator dupComm
     (
         UPstream::worldComm,
-        identity(UPstream::nProcs(UPstream::worldComm))
+        labelRange(UPstream::nProcs(UPstream::worldComm))
     );
 
     const label comm = dupComm.comm();
     const label oldWarnComm = UPstream::commWarn(comm);
 
+    FixedList<label, 3> totals;
 
-    // Total number of faces.
-    nTotalFaces_ = returnReduce
-    (
-        mesh_.nFaces(),
-        sumOp<label>(),
-        UPstream::msgType(),
-        comm
-    );
+    totals[0] = mesh_.nPoints();
+    totals[1] = mesh_.nFaces();
+    totals[2] = mesh_.nCells();
 
-    if (debug)
-    {
-        Pout<< "globalMeshData : nTotalFaces:" << nTotalFaces_ << endl;
-    }
+    reduce(totals, sumOp<label>(), UPstream::msgType(), comm);
 
-    nTotalCells_ = returnReduce
-    (
-        mesh_.nCells(),
-        sumOp<label>(),
-        UPstream::msgType(),
-        comm
-    );
-
-    if (debug)
-    {
-        Pout<< "globalMeshData : nTotalCells:" << nTotalCells_ << endl;
-    }
-
-    nTotalPoints_ = returnReduce
-    (
-        mesh_.nPoints(),
-        sumOp<label>(),
-        UPstream::msgType(),
-        comm
-    );
+    nTotalPoints_ = totals[0];
+    nTotalFaces_ = totals[1];
+    nTotalCells_ = totals[2];
 
     // Restore communicator settings
     UPstream::commWarn(oldWarnComm);
-    dupComm.reset();
 
     if (debug)
     {
-        Pout<< "globalMeshData : nTotalPoints:" << nTotalPoints_ << endl;
+        Info<< "globalMeshData : Total points/faces/cells : "
+            << totals << endl;
     }
 }
 
diff --git a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H
index fb75f9677e..b9a70712c5 100644
--- a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H
+++ b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H
@@ -348,22 +348,22 @@ public:
                 return mesh_;
             }
 
-            //- Does the mesh contain processor patches? (also valid when
-            //  not running parallel)
-            bool parallel() const
+            //- Does the mesh contain processor patches?
+            //- (also valid when not running parallel)
+            bool parallel() const noexcept
             {
                 return !processorPatches_.empty();
             }
 
-            //- Return total number of points in decomposed mesh. Not
-            //  compensated for duplicate points!
+            //- Return total number of points in decomposed mesh.
+            //- Not compensated for duplicate points!
             label nTotalPoints() const noexcept
             {
                 return nTotalPoints_;
             }
 
-            //- Return total number of faces in decomposed mesh. Not
-            //  compensated for duplicate faces!
+            //- Return total number of faces in decomposed mesh.
+            //- Not compensated for duplicate faces!
             label nTotalFaces() const noexcept
             {
                 return nTotalFaces_;