ENH: use List containers for Pstream read/write calls

- using the List containers, and not their low-level data_bytes(),
  size_bytes() methods is more convenient and allows future
  adjustments to be centralized

ENH: trivial intptr_t wrapper for MPI_Win

STYLE: minor adjustments to mpirunDebug

bin/mpirunDebug

@@ -24,7 +24,6 @@
 . "${WM_PROJECT_DIR:?}"/bin/tools/RunFunctions  # Run functions
 
 printHelp() {
-    exec 1>&2
     cat<<USAGE
 
 Usage: ${0##*/} [OPTION] -np <N> <executable> <args>
@@ -203,7 +202,7 @@ do
 
     # Processing application arguments
     case "$1" in
-    (-help* | --help*) usage ;;
+    (-help* | --help*) printHelp ;;
     ('') ;;  ## Ignore junk
 
     (-np)
@@ -235,15 +234,16 @@ done
 # Cleanup only
 if [ -n "$optClean" ]
 then
-    echo "Cleanup old mpirunDebug files..." 1>&2
+    exec 1>&2
-    rm -f gdbCommands    mpirun.schema
+    echo "Cleanup old mpirunDebug files..."
-    rm -rf mpirun.log mpirun.files
+    rm -f gdbCommands mpirun.schema vgcore.*
     rm -f processor*.log processor*.sh
-    echo "    gdbCommands     mpirun.schema" 1>&2
+    rm -rf mpirun.log mpirun.files
-    echo "    mpirun.{files,log}/" 1>&2
+    echo "    gdbCommands mpirun.schema vgcore.*"
-    echo "    processor*.{log,sh}" 1>&2
+    echo "    processor*.{log,sh}"
-    echo "Done" 1>&2
+    echo "    mpirun.{files,log}/"
-    exit 0
+    echo "Done"
+    exit 0  # A clean exit
 fi
 
 
@@ -344,12 +344,15 @@ esac
 
 echo "**sourceFoam: $sourceFoam" 1>&2
 
-rm -f ./mpirun.schema
-touch ./mpirun.schema
-
 mkdir -p ./mpirun.files
 mkdir -p ./mpirun.log
 
+schema_file="$PWD/mpirun.files/mpirun.schema"
+
+rm -f "$schema_file"
+touch "$schema_file"
+
+
 proc=0
 xpos=0
 ypos=0
@@ -374,8 +377,8 @@ COMMANDS
 
     # Add to the mpirun.schema
     case "$method" in
-    (*xterm*) echo "${node}${xterm} -e ${procCmdFile}" >> "$PWD"/mpirun.schema ;;
+    (*xterm*) echo "${node}${xterm} -e ${procCmdFile}" >> "$schema_file" ;;
-    (*)       echo "${node}${procCmdFile}" >> "$PWD"/mpirun.schema ;;
+    (*)       echo "${node}${procCmdFile}" >> "$schema_file" ;;
     esac
 
     case "$method" in
@@ -421,17 +424,33 @@ COMMANDS
     fi
 done
 
+
+if [ "$nProcs" -lt 10 ]
+then
     for ((proc = 0; proc < $nProcs; proc++))
     do
         procLog="mpirun.log/processor${proc}.log"
         echo "    tail -f $procLog" 1>&2
     done
+else
+    for ((proc = 0; proc < 4; proc++))
+    do
+        procLog="mpirun.log/processor${proc}.log"
+        echo "    tail -f $procLog" 1>&2
+    done
+    echo "    ..." 1>&2
+    for ((proc = $nProcs-2; proc < $nProcs; proc++))
+    do
+        procLog="mpirun.log/processor${proc}.log"
+        echo "    tail -f $procLog" 1>&2
+    done
+fi
 
 unset cmd
 
 case "$WM_MPLIB" in
 *OPENMPI*)
-    cmd="mpirun --oversubscribe -app $PWD/mpirun.schema </dev/null"
+    cmd="mpirun --oversubscribe -app "$schema_file" </dev/null"
     ;;
 MPICH)
     cmd="mpiexec"
@@ -448,7 +467,7 @@ MPICH)
             cmd="${cmd} :"
         fi
         cmd="${cmd} -n 1 ${procXtermCmdFile}"
-    done < "$PWD"/mpirun.schema
+    done < "$schema_file"
     ;;
 *)
     die "Unsupported WM_MPLIB setting : $WM_MPLIB"
@@ -456,7 +475,7 @@ MPICH)
 esac
 
 echo 1>&2
-echo "Constructed $PWD/mpirun.schema file:" 1>&2
+echo "Constructed $schema_file file:" 1>&2
 echo 1>&2
 echo "    $cmd" 1>&2
 echo 1>&2

src/OpenFOAM/db/IOstreams/Pstreams/PstreamCombineGather.C

@@ -182,8 +182,7 @@ void Foam::Pstream::listCombineGather
                 (
                     UPstream::commsTypes::scheduled,
                     belowID,
-                    received.data_bytes(),
+                    received,
-                    received.size_bytes(),
                     tag,
                     comm
                 );
@@ -239,8 +238,7 @@ void Foam::Pstream::listCombineGather
                 (
                     UPstream::commsTypes::scheduled,
                     myComm.above(),
-                    values.cdata_bytes(),
+                    values,
-                    values.size_bytes(),
                     tag,
                     comm
                 );

src/OpenFOAM/db/IOstreams/Pstreams/PstreamGatherList.C

@@ -80,8 +80,7 @@ void Foam::Pstream::gatherList
                 (
                     UPstream::commsTypes::scheduled,
                     belowID,
-                    received.data_bytes(),
+                    received,
-                    received.size_bytes(),
                     tag,
                     comm
                 );
@@ -155,8 +154,7 @@ void Foam::Pstream::gatherList
                 (
                     UPstream::commsTypes::scheduled,
                     myComm.above(),
-                    sending.cdata_bytes(),
+                    sending,
-                    sending.size_bytes(),
                     tag,
                     comm
                 );
@@ -231,8 +229,7 @@ void Foam::Pstream::scatterList
                 (
                     UPstream::commsTypes::scheduled,
                     myComm.above(),
-                    received.data_bytes(),
+                    received,
-                    received.size_bytes(),
                     tag,
                     comm
                 );
@@ -286,8 +283,7 @@ void Foam::Pstream::scatterList
                 (
                     UPstream::commsTypes::scheduled,
                     belowID,
-                    sending.cdata_bytes(),
+                    sending,
-                    sending.size_bytes(),
                     tag,
                     comm
                 );

src/OpenFOAM/db/IOstreams/Pstreams/UPstream.C

@@ -94,7 +94,7 @@ static List<int> getHostGroupIds(const label parentCommunicator)
     (
         myDigest.cdata_bytes(),     // Send
         digests.data_bytes(),       // Recv
-        SHA1Digest::max_size(),     // Num send/recv data per rank
+        SHA1Digest::size_bytes(),   // Num send/recv data per rank
         parentCommunicator
     );
 

src/OpenFOAM/db/IOstreams/Pstreams/UPstream.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2015-2024 OpenCFD Ltd.
+    Copyright (C) 2015-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -99,6 +99,9 @@ public:
         //- Wrapper for MPI_Request
         class Request;  // Forward Declaration
 
+        //- Wrapper for MPI_Win
+        class Window;  // Forward Declaration
+
         //- Structure for communicating between processors
         class commsStruct
         {
@@ -1462,6 +1465,12 @@ UList<UPstream::commsStruct>::operator[](const label procID) const;
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+// Traits, nested classes etc
+#include "UPstreamTraits.H"
+#include "UPstreamWindow.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
 #ifdef NoRepository
     #include "UPstreamTemplates.C"
 #endif

src/OpenFOAM/db/IOstreams/Pstreams/UPstreamTraits.H

@@ -0,0 +1,46 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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/>.
+
+Description
+    A set of traits associated with UPstream communication
+
+SourceFiles
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_UPstreamTraits_H
+#define Foam_UPstreamTraits_H
+
+#include "UPstream.H"
+#include <cstdint>
+#include <ios>  // For streamsize
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/db/IOstreams/Pstreams/UPstreamWindow.H

@@ -0,0 +1,152 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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::UPstream::Window
+
+Description
+    An opaque wrapper for MPI_Win with a vendor-independent
+    representation and without any \c <mpi.h> header dependency.
+
+Note
+    The MPI standard states that MPI_Win is always an opaque object.
+    Generally it is either an integer (eg, mpich) or a pointer (eg, openmpi).
+
+SourceFiles
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_UPstreamWindow_H
+#define Foam_UPstreamWindow_H
+
+#include "UPstream.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                      Class UPstream::Window Declaration
+\*---------------------------------------------------------------------------*/
+
+class UPstream::Window
+{
+public:
+
+    // Public Types
+
+        //- Storage for MPI_Win (as integer or pointer)
+        typedef std::intptr_t value_type;
+
+
+private:
+
+    // Private Data
+
+        //- The MPI_Win (as wrapped value)
+        value_type value_;
+
+public:
+
+    // Generated Methods
+
+        //- Copy construct
+        Window(const Window&) noexcept = default;
+
+        //- Move construct
+        Window(Window&&) noexcept = default;
+
+        //- Copy assignment
+        Window& operator=(const Window&) noexcept = default;
+
+        //- Move assignment
+        Window& operator=(Window&&) noexcept = default;
+
+
+    // Member Operators
+
+        //- Test for equality
+        bool operator==(const Window& rhs) const noexcept
+        {
+            return (value_ == rhs.value_);
+        }
+
+        //- Test for inequality
+        bool operator!=(const Window& rhs) const noexcept
+        {
+            return (value_ != rhs.value_);
+        }
+
+
+    // Constructors
+
+        //- Default construct as MPI_WIN_NULL
+        Window() noexcept;
+
+        //- Construct from MPI_Win (as pointer type)
+        explicit Window(const void* p) noexcept
+        :
+            value_(reinterpret_cast<value_type>(p))
+        {}
+
+        //- Construct from MPI_Win (as integer type)
+        explicit Window(value_type val) noexcept
+        :
+            value_(val)
+        {}
+
+
+    // Member Functions
+
+    // Basic handling
+
+        //- Return raw value
+        value_type value() const noexcept { return value_; }
+
+        //- Return as pointer value
+        const void* pointer() const noexcept
+        {
+            return reinterpret_cast<const void*>(value_);
+        }
+
+        //- True if not equal to MPI_WIN_NULL
+        bool good() const noexcept;
+
+        //- Reset to default constructed value (MPI_WIN_NULL)
+        void reset() noexcept;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/fields/pointPatchFields/constraint/processorCyclic/processorCyclicPointPatchField.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2020-2023 OpenCFD Ltd.
+    Copyright (C) 2020-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -113,8 +113,7 @@ void Foam::processorCyclicPointPatchField<Type>::initSwapAddSeparated
             (
                 commsType,
                 procPatch_.neighbProcNo(),
-                recvBuf_.data_bytes(),
+                recvBuf_,
-                recvBuf_.size_bytes(),
                 procPatch_.tag(),
                 procPatch_.comm()
             );
@@ -123,8 +122,7 @@ void Foam::processorCyclicPointPatchField<Type>::initSwapAddSeparated
         (
             commsType,
             procPatch_.neighbProcNo(),
-            sendBuf_.cdata_bytes(),
+            sendBuf_,
-            sendBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );
@@ -150,8 +148,7 @@ void Foam::processorCyclicPointPatchField<Type>::swapAddSeparated
             (
                 commsType,
                 procPatch_.neighbProcNo(),
-                recvBuf_.data_bytes(),
+                recvBuf_,
-                recvBuf_.size_bytes(),
                 procPatch_.tag(),
                 procPatch_.comm()
             );

src/OpenFOAM/global/fileOperations/fileOperation/fileOperationRanks.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2022-2023 OpenCFD Ltd.
+    Copyright (C) 2022-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -126,7 +126,7 @@ Foam::labelList Foam::fileOperation::getGlobalHostIORanks()
     (
         myDigest.cdata_bytes(),     // Send
         digests.data_bytes(),       // Recv
-        SHA1Digest::max_size(),     // Num send/recv per rank
+        SHA1Digest::size_bytes(),   // Num send/recv per rank
         UPstream::worldComm
     );
 

src/OpenFOAM/include/openfoam_mpi.H

@@ -80,6 +80,20 @@ struct Cast
             return static_cast<Type>(arg.value());
         }
     }
+
+    //- Cast UPstream::Window to MPI_Win
+    template<typename Type = MPI_Win>
+    static Type to_mpi(UPstream::Window arg) noexcept
+    {
+        if constexpr (std::is_pointer_v<Type>)
+        {
+            return reinterpret_cast<Type>(arg.value());
+        }
+        else  // std::is_integral_v<Type>
+        {
+            return static_cast<Type>(arg.value());
+        }
+    }
 };
 
 

src/OpenFOAM/matrices/LUscalarMatrix/LUscalarMatrixTemplates.C

@@ -78,8 +78,7 @@ void Foam::LUscalarMatrix::solve
                     (
                         UPstream::commsTypes::nonBlocking,
                         proci,
-                        procSlot.data_bytes(),
+                        procSlot,
-                        procSlot.size_bytes(),
                         tag,
                         comm_
                     );
@@ -102,8 +101,7 @@ void Foam::LUscalarMatrix::solve
                 (
                     UPstream::commsTypes::nonBlocking,
                     UPstream::masterNo(),
-                    x.cdata_bytes(),
+                    x,
-                    x.size_bytes(),
                     tag,
                     comm_
                 );
@@ -142,8 +140,7 @@ void Foam::LUscalarMatrix::solve
                     (
                         UPstream::commsTypes::nonBlocking,
                         proci,
-                        procSlot.cdata_bytes(),
+                        procSlot,
-                        procSlot.size_bytes(),
                         tag,
                         comm_
                     );
@@ -166,8 +163,7 @@ void Foam::LUscalarMatrix::solve
                 (
                     UPstream::commsTypes::nonBlocking,
                     UPstream::masterNo(),
-                    x.data_bytes(),
+                    x,
-                    x.size_bytes(),
                     tag,
                     comm_
                 );

src/OpenFOAM/matrices/lduMatrix/lduAddressing/lduInterface/lduCalculatedProcessorField/lduCalculatedProcessorField.C

@@ -114,8 +114,7 @@ void Foam::lduCalculatedProcessorField<Type>::initInterfaceMatrixUpdate
     (
         UPstream::commsTypes::nonBlocking,
         procInterface_.neighbProcNo(),
-        scalarRecvBuf_.data_bytes(),
+        scalarRecvBuf_,
-        scalarRecvBuf_.size_bytes(),
         procInterface_.tag(),
         procInterface_.comm()
     );
@@ -125,8 +124,7 @@ void Foam::lduCalculatedProcessorField<Type>::initInterfaceMatrixUpdate
     (
         UPstream::commsTypes::nonBlocking,
         procInterface_.neighbProcNo(),
-        scalarSendBuf_.cdata_bytes(),
+        scalarSendBuf_,
-        scalarSendBuf_.size_bytes(),
         procInterface_.tag(),
         procInterface_.comm()
     );

src/OpenFOAM/matrices/lduMatrix/lduAddressing/lduInterface/processorLduInterfaceTemplates.C

@@ -56,8 +56,7 @@ void Foam::processorLduInterface::send
         (
             commsType,
             neighbProcNo(),
-            fld.cdata_bytes(),
+            fld,
-            fld.size_bytes(),
             tag(),
             comm()
         );
@@ -133,8 +132,7 @@ void Foam::processorLduInterface::receive
         (
             commsType,
             neighbProcNo(),
-            fld.data_bytes(),
+            fld,
-            fld.size_bytes(),
             tag(),
             comm()
         );

src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/interfaceFields/processorGAMGInterfaceField/processorGAMGInterfaceField.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2019-2023 OpenCFD Ltd.
+    Copyright (C) 2019-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -149,8 +149,7 @@ void Foam::processorGAMGInterfaceField::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procInterface_.neighbProcNo(),
-            scalarRecvBuf_.data_bytes(),
+            scalarRecvBuf_,
-            scalarRecvBuf_.size_bytes(),
             procInterface_.tag(),
             comm()
         );
@@ -160,8 +159,7 @@ void Foam::processorGAMGInterfaceField::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procInterface_.neighbProcNo(),
-            scalarSendBuf_.cdata_bytes(),
+            scalarSendBuf_,
-            scalarSendBuf_.size_bytes(),
             procInterface_.tag(),
             comm()
         );

src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBaseTemplates.C

@@ -201,8 +201,7 @@ void Foam::mapDistributeBase::send
             (
                 UPstream::commsTypes::nonBlocking,
                 proci,
-                subField.data_bytes(),
+                subField,
-                subField.size_bytes(),
                 tag,
                 comm
             );
@@ -244,8 +243,7 @@ void Foam::mapDistributeBase::send
             (
                 UPstream::commsTypes::nonBlocking,
                 proci,
-                subField.cdata_bytes(),
+                subField,
-                subField.size_bytes(),
                 tag,
                 comm
             );
@@ -778,8 +776,7 @@ void Foam::mapDistributeBase::distribute
                     (
                         UPstream::commsTypes::nonBlocking,
                         proci,
-                        subField.data_bytes(),
+                        subField,
-                        subField.size_bytes(),
                         tag,
                         comm
                     );
@@ -806,8 +803,7 @@ void Foam::mapDistributeBase::distribute
                     (
                         UPstream::commsTypes::nonBlocking,
                         proci,
-                        subField.cdata_bytes(),
+                        subField,
-                        subField.size_bytes(),
                         tag,
                         comm
                     );
@@ -1218,8 +1214,7 @@ void Foam::mapDistributeBase::distribute
                     (
                         UPstream::commsTypes::nonBlocking,
                         proci,
-                        subField.data_bytes(),
+                        subField,
-                        subField.size_bytes(),
                         tag,
                         comm
                     );
@@ -1246,8 +1241,7 @@ void Foam::mapDistributeBase::distribute
                     (
                         UPstream::commsTypes::nonBlocking,
                         proci,
-                        subField.cdata_bytes(),
+                        subField,
-                        subField.size_bytes(),
                         tag,
                         comm
                     );

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

@@ -1086,8 +1086,7 @@ void Foam::syncTools::syncBoundaryFaceList
                     (
                         UPstream::commsTypes::nonBlocking,
                         procPatch.neighbProcNo(),
-                        fld.data_bytes(),
+                        fld
-                        fld.size_bytes()
                     );
                 }
             }
@@ -1112,8 +1111,7 @@ void Foam::syncTools::syncBoundaryFaceList
                     (
                         UPstream::commsTypes::nonBlocking,
                         procPatch.neighbProcNo(),
-                        fld.cdata_bytes(),
+                        fld
-                        fld.size_bytes()
                     );
                 }
             }

src/OpenFOAM/parallel/globalIndex/globalIndexTemplates.C

@@ -259,8 +259,7 @@ void Foam::globalIndex::gather
                 (
                     commsType,
                     procIDs[i],
-                    procSlot.data_bytes(),
+                    procSlot,
-                    procSlot.size_bytes(),
                     tag,
                     comm
                 );
@@ -283,8 +282,7 @@ void Foam::globalIndex::gather
             (
                 commsType,
                 masterProci,
-                fld.cdata_bytes(),
+                fld,
-                fld.size_bytes(),
                 tag,
                 comm
             );
@@ -948,8 +946,7 @@ void Foam::globalIndex::scatter
                 (
                     commsType,
                     procIDs[i],
-                    procSlot.cdata_bytes(),
+                    procSlot,
-                    procSlot.size_bytes(),
                     tag,
                     comm
                 );
@@ -984,8 +981,7 @@ void Foam::globalIndex::scatter
             (
                 commsType,
                 masterProci,
-                fld.data_bytes(),
+                fld,
-                fld.size_bytes(),
                 tag,
                 comm
             );

src/Pstream/dummy/Make/files

@@ -5,6 +5,7 @@ UPstreamCommunicator.C
 UPstreamGatherScatter.C
 UPstreamReduce.C
 UPstreamRequest.C
+UPstreamWindow.C
 
 UIPstreamRead.C
 UOPstreamWrite.C

src/Pstream/dummy/UPstreamWindow.C

@@ -0,0 +1,50 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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 "UPstream.H"
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::UPstream::Window::Window() noexcept
+:
+    UPstream::Window(nullptr)
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+bool Foam::UPstream::Window::good() const noexcept
+{
+    return false;
+}
+
+
+void Foam::UPstream::Window::reset() noexcept
+{}
+
+
+// ************************************************************************* //

src/Pstream/mpi/Make/files

@@ -6,6 +6,7 @@ UPstreamCommunicator.C
 UPstreamGatherScatter.C
 UPstreamReduce.C
 UPstreamRequest.C
+UPstreamWindow.C
 
 UIPstreamRead.C
 UOPstreamWrite.C

src/Pstream/mpi/UPstreamWindow.C

@@ -0,0 +1,53 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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 "PstreamGlobals.H"
+#include "profilingPstream.H"
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::UPstream::Window::Window() noexcept
+:
+    UPstream::Window(MPI_WIN_NULL)
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+bool Foam::UPstream::Window::good() const noexcept
+{
+    return MPI_WIN_NULL != PstreamUtils::Cast::to_mpi(*this);
+}
+
+
+void Foam::UPstream::Window::reset() noexcept
+{
+    *this = UPstream::Window(MPI_WIN_NULL);
+}
+
+
+// ************************************************************************* //

src/fileFormats/ensight/output/ensightOutputTemplates.C

@@ -217,8 +217,7 @@ void Foam::ensightOutput::Detail::writeFieldComponents
                     (
                         UPstream::commsTypes::scheduled,
                         proci,
-                        slot.data_bytes(),
+                        slot
-                        slot.size_bytes()
                     );
                 }
             }
@@ -244,8 +243,7 @@ void Foam::ensightOutput::Detail::writeFieldComponents
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                scratch.cdata_bytes(),
+                scratch
-                scratch.size_bytes()
             );
         }
     }

src/fileFormats/vtk/output/foamVtkOutput.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2022 OpenCFD Ltd.
+    Copyright (C) 2016-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -155,8 +155,7 @@ void Foam::vtk::writeListParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
 
                 // With value offset
@@ -176,8 +175,7 @@ void Foam::vtk::writeListParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                values.cdata_bytes(),
+                values
-                values.size_bytes()
             );
         }
     }

src/fileFormats/vtk/output/foamVtkOutputTemplates.C

@@ -193,8 +193,7 @@ void Foam::vtk::writeListParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
                 vtk::writeList(fmt, recvData);
             }
@@ -208,8 +207,7 @@ void Foam::vtk::writeListParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                values.cdata_bytes(),
+                values
-                values.size_bytes()
             );
         }
     }
@@ -262,8 +260,7 @@ void Foam::vtk::writeListParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
                 vtk::writeList(fmt, recvData);
             }
@@ -277,8 +274,7 @@ void Foam::vtk::writeListParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                sendData.cdata_bytes(),
+                sendData
-                sendData.size_bytes()
             );
         }
     }
@@ -332,8 +328,7 @@ void Foam::vtk::writeListParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
                 vtk::writeList(fmt, recvData);
             }
@@ -347,8 +342,7 @@ void Foam::vtk::writeListParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                sendData.cdata_bytes(),
+                sendData
-                sendData.size_bytes()
             );
         }
     }
@@ -401,8 +395,7 @@ void Foam::vtk::writeListsParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
                 vtk::writeList(fmt, recvData);
             }
@@ -417,8 +410,7 @@ void Foam::vtk::writeListsParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
                 vtk::writeList(fmt, recvData);
             }
@@ -432,8 +424,7 @@ void Foam::vtk::writeListsParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                values1.cdata_bytes(),
+                values1
-                values1.size_bytes()
             );
         }
 
@@ -443,8 +434,7 @@ void Foam::vtk::writeListsParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                values2.cdata_bytes(),
+                values2
-                values2.size_bytes()
             );
         }
     }
@@ -506,8 +496,7 @@ void Foam::vtk::writeListsParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
                 vtk::writeList(fmt, recvData);
             }
@@ -522,8 +511,7 @@ void Foam::vtk::writeListsParallel
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
                 vtk::writeList(fmt, recvData);
             }
@@ -537,8 +525,7 @@ void Foam::vtk::writeListsParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                values1.cdata_bytes(),
+                values1
-                values1.size_bytes()
             );
         }
 
@@ -548,8 +535,7 @@ void Foam::vtk::writeListsParallel
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                sendData2.cdata_bytes(),
+                sendData2
-                sendData2.size_bytes()
             );
         }
     }

src/finiteArea/fields/faPatchFields/constraint/processor/processorFaPatchField.C

@@ -227,15 +227,15 @@ void Foam::processorFaPatchField<Type>::initEvaluate
             }
 
             // Receive straight into *this
-            this->resize_nocopy(sendBuf_.size());
+            Field<Type>& self = *this;
+            self.resize_nocopy(sendBuf_.size());
 
             recvRequest_ = UPstream::nRequests();
             UIPstream::read
             (
                 UPstream::commsTypes::nonBlocking,
                 procPatch_.neighbProcNo(),
-                this->data_bytes(),
+                self,
-                this->size_bytes(),
                 procPatch_.tag(),
                 procPatch_.comm()
             );
@@ -245,8 +245,7 @@ void Foam::processorFaPatchField<Type>::initEvaluate
             (
                 UPstream::commsTypes::nonBlocking,
                 procPatch_.neighbProcNo(),
-                sendBuf_.cdata_bytes(),
+                sendBuf_,
-                sendBuf_.size_bytes(),
                 procPatch_.tag(),
                 procPatch_.comm()
             );
@@ -328,8 +327,7 @@ void Foam::processorFaPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            scalarRecvBuf_.data_bytes(),
+            scalarRecvBuf_,
-            scalarRecvBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );
@@ -339,8 +337,7 @@ void Foam::processorFaPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            scalarSendBuf_.cdata_bytes(),
+            scalarSendBuf_,
-            scalarSendBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );
@@ -434,8 +431,7 @@ void Foam::processorFaPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            recvBuf_.data_bytes(),
+            recvBuf_,
-            recvBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );
@@ -445,8 +441,7 @@ void Foam::processorFaPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            sendBuf_.cdata_bytes(),
+            sendBuf_,
-            sendBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );

src/finiteVolume/fields/fvPatchFields/constraint/calculatedProcessor/calculatedProcessorFvPatchField.C

@@ -138,15 +138,15 @@ void Foam::calculatedProcessorFvPatchField<Type>::initEvaluate
         }
 
         // Receive straight into *this
-        this->resize_nocopy(sendBuf_.size());
+        Field<Type>& self = *this;
+        self.resize_nocopy(sendBuf_.size());
 
         recvRequest_ = UPstream::nRequests();
         UIPstream::read
         (
             UPstream::commsTypes::nonBlocking,
             procInterface_.neighbProcNo(),
-            this->data_bytes(),
+            self,
-            this->size_bytes(),
             procInterface_.tag(),
             procInterface_.comm()
         );
@@ -156,8 +156,7 @@ void Foam::calculatedProcessorFvPatchField<Type>::initEvaluate
         (
             UPstream::commsTypes::nonBlocking,
             procInterface_.neighbProcNo(),
-            sendBuf_.cdata_bytes(),
+            sendBuf_,
-            sendBuf_.size_bytes(),
             procInterface_.tag(),
             procInterface_.comm()
         );
@@ -218,8 +217,7 @@ void Foam::calculatedProcessorFvPatchField<Type>::initInterfaceMatrixUpdate
     (
         UPstream::commsTypes::nonBlocking,
         procInterface_.neighbProcNo(),
-        scalarRecvBuf_.data_bytes(),
+        scalarRecvBuf_,
-        scalarRecvBuf_.size_bytes(),
         procInterface_.tag(),
         procInterface_.comm()
     );
@@ -229,8 +227,7 @@ void Foam::calculatedProcessorFvPatchField<Type>::initInterfaceMatrixUpdate
     (
         UPstream::commsTypes::nonBlocking,
         procInterface_.neighbProcNo(),
-        scalarSendBuf_.cdata_bytes(),
+        scalarSendBuf_,
-        scalarSendBuf_.size_bytes(),
         procInterface_.tag(),
         procInterface_.comm()
     );

src/finiteVolume/fields/fvPatchFields/constraint/processor/processorFvPatchField.C

@@ -232,15 +232,15 @@ void Foam::processorFvPatchField<Type>::initEvaluate
             }
 
             // Receive straight into *this
-            this->resize_nocopy(sendBuf_.size());
+            Field<Type>& self = *this;
+            self.resize_nocopy(sendBuf_.size());
 
             recvRequest_ = UPstream::nRequests();
             UIPstream::read
             (
                 UPstream::commsTypes::nonBlocking,
                 procPatch_.neighbProcNo(),
-                this->data_bytes(),
+                self,
-                this->size_bytes(),
                 procPatch_.tag(),
                 procPatch_.comm()
             );
@@ -250,8 +250,7 @@ void Foam::processorFvPatchField<Type>::initEvaluate
             (
                 UPstream::commsTypes::nonBlocking,
                 procPatch_.neighbProcNo(),
-                sendBuf_.cdata_bytes(),
+                sendBuf_,
-                sendBuf_.size_bytes(),
                 procPatch_.tag(),
                 procPatch_.comm()
             );
@@ -353,8 +352,7 @@ void Foam::processorFvPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            scalarRecvBuf_.data_bytes(),
+            scalarRecvBuf_,
-            scalarRecvBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );
@@ -364,8 +362,7 @@ void Foam::processorFvPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            scalarSendBuf_.cdata_bytes(),
+            scalarSendBuf_,
-            scalarSendBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );
@@ -474,8 +471,7 @@ void Foam::processorFvPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            recvBuf_.data_bytes(),
+            recvBuf_,
-            recvBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );
@@ -485,8 +481,7 @@ void Foam::processorFvPatchField<Type>::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procPatch_.neighbProcNo(),
-            sendBuf_.cdata_bytes(),
+            sendBuf_,
-            sendBuf_.size_bytes(),
             procPatch_.tag(),
             procPatch_.comm()
         );

src/lagrangian/intermediate/conversion/ensight/ensightOutputCloud.C

@@ -143,8 +143,7 @@ bool Foam::ensightOutput::writeCloudPositions
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    positions.data_bytes(),
+                    positions
-                    positions.size_bytes()
                 );
 
                 if (isBinaryOutput)
@@ -166,8 +165,7 @@ bool Foam::ensightOutput::writeCloudPositions
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                positions.cdata_bytes(),
+                positions
-                positions.size_bytes()
             );
         }
     }

src/lagrangian/intermediate/conversion/ensight/ensightOutputCloudTemplates.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2024 OpenCFD Ltd.
+    Copyright (C) 2016-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -110,8 +110,7 @@ bool Foam::ensightOutput::writeCloudField
                 (
                     UPstream::commsTypes::scheduled,
                     proci,
-                    recvData.data_bytes(),
+                    recvData
-                    recvData.size_bytes()
                 );
 
                 count = ensightOutput::Detail::writeCloudFieldContent
@@ -137,8 +136,7 @@ bool Foam::ensightOutput::writeCloudField
             (
                 UPstream::commsTypes::scheduled,
                 UPstream::masterNo(),
-                field.cdata_bytes(),
+                field
-                field.size_bytes()
             );
         }
     }

src/meshTools/matrices/lduMatrix/preconditioners/distributedDILUPreconditioner/distributedDILUPreconditioner.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2023 OpenCFD Ltd.
+    Copyright (C) 2023-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -194,13 +194,11 @@ void Foam::distributedDILUPreconditioner::receive
         auto& recvBuf = recvBufs_[inti];
         recvBuf.resize_nocopy(interfaceBouCoeffs[inti].size());
 
-        requests.push_back(UPstream::Request());
         UIPstream::read
         (
-            requests.back(),
+            requests.emplace_back(),
             ppp->neighbProcNo(),
-            recvBuf.data_bytes(),
+            recvBuf,
-            recvBuf.size_bytes(),
             ppp->tag()+70,          // random offset
             ppp->comm()
         );
@@ -232,13 +230,11 @@ void Foam::distributedDILUPreconditioner::send
             sendBuf[face] = psiInternal[faceCells[face]];
         }
 
-        requests.push_back(UPstream::Request());
         UOPstream::write
         (
-            requests.back(),
+            requests.emplace_back(),
             ppp->neighbProcNo(),
-            sendBuf.cdata_bytes(),
+            sendBuf,
-            sendBuf.size_bytes(),
             ppp->tag()+70,          // random offset
             ppp->comm()
         );

src/overset/lduPrimitiveProcessorInterface/GAMG/calculatedProcessorGAMGInterfaceField.C

@@ -139,8 +139,7 @@ void Foam::calculatedProcessorGAMGInterfaceField::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procInterface_.neighbProcNo(),
-            scalarRecvBuf_.data_bytes(),
+            scalarRecvBuf_,
-            scalarRecvBuf_.size_bytes(),
             procInterface_.tag(),
             comm()
         );
@@ -150,8 +149,7 @@ void Foam::calculatedProcessorGAMGInterfaceField::initInterfaceMatrixUpdate
         (
             UPstream::commsTypes::nonBlocking,
             procInterface_.neighbProcNo(),
-            scalarSendBuf_.cdata_bytes(),
+            scalarSendBuf_,
-            scalarSendBuf_.size_bytes(),
             procInterface_.tag(),
             comm()
         );

src/parallel/decompose/decompositionMethods/metisLikeDecomp/metisLikeDecomp.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017-2024 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -100,8 +100,7 @@ Foam::label Foam::metisLikeDecomp::decomposeGeneral
                 (
                     commsType,
                     proci,
-                    procSlot.data_bytes(),
+                    procSlot,
-                    procSlot.size_bytes(),
                     UPstream::msgType(),
                     UPstream::worldComm
                 );
@@ -124,8 +123,7 @@ Foam::label Foam::metisLikeDecomp::decomposeGeneral
             (
                 commsType,
                 UPstream::masterNo(),
-                procSlot.cdata_bytes(),
+                procSlot,
-                procSlot.size_bytes(),
                 UPstream::msgType(),
                 UPstream::worldComm
             );