ENH: support UOPstream and UIPstream as formatters with an external buffer

- can split serialise/de-serialise and send/recv actions

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

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -75,13 +75,12 @@ Foam::IPBstream::IPBstream
         commsType,
         fromProcNo,
         Pstream::transferBuf_,
-        transferBufPosition_,
+        UIPstreamBase::storedRecvBufPos_,   // Internal only
         tag,
         comm,
         false,  // Do not clear Pstream::transferBuf_ if at end
         fmt
-    ),
-    transferBufPosition_(0)
+    )
 {}
 
 

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

@@ -56,11 +56,6 @@ class IPstream
     public Pstream,
     public UIPstream
 {
-    // Private Data
-
-        //- Receive index into Pstream::transferBuf_
-        label transferBufPosition_;
-
 public:
 
     // Constructors
@@ -90,11 +85,6 @@ class IPBstream
     public Pstream,
     public UIPBstream
 {
-    // Private Data
-
-        //- Receive index into Pstream::transferBuf_
-        label transferBufPosition_;
-
 public:
 
     // Constructors

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

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -91,6 +91,16 @@ Foam::UIPstream::UIPstream(const int fromProcNo, PstreamBuffers& buffers)
 }
 
 
+Foam::UIPstream::UIPstream
+(
+    const DynamicList<char>& recvBuf,
+    IOstreamOption::streamFormat fmt
+)
+:
+    UIPstreamBase(recvBuf, fmt)
+{}
+
+
 Foam::IPstream::IPstream
 (
     const UPstream::commsTypes commsType,
@@ -107,13 +117,12 @@ Foam::IPstream::IPstream
         commsType,
         fromProcNo,
         Pstream::transferBuf_,
-        transferBufPosition_,
+        UIPstreamBase::storedRecvBufPos_,   // Internal only
         tag,
         comm,
         false,  // Do not clear Pstream::transferBuf_ if at end
         fmt
-    ),
-    transferBufPosition_(0)
+    )
 {}
 
 

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

@@ -52,6 +52,16 @@ Foam::UOPstream::UOPstream(const int toProcNo, PstreamBuffers& buffers)
 {}
 
 
+Foam::UOPstream::UOPstream
+(
+    DynamicList<char>& sendBuf,
+    IOstreamOption::streamFormat fmt
+)
+:
+    UOPstreamBase(sendBuf, fmt)
+{}
+
+
 Foam::OPstream::OPstream
 (
     const UPstream::commsTypes commsType,

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

@@ -85,19 +85,30 @@ protected:
 
     // Protected Data
 
-        int fromProcNo_;
-
-        DynamicList<char>& recvBuf_;
-
-        label& recvBufPos_;
+        //- Source rank for the data
+        const int fromProcNo_;
 
+        //- Message tag for communication
         const int tag_;
 
-        const label comm_;
+        //- The communicator index
+        const int comm_;
 
+        //- The message size, read on bufferIPCrecv or set directly
+        int messageSize_;
+
+        //- Receive position in buffer data, if ony
+        //- If there is no external location for recvBufPos_
+        label storedRecvBufPos_;
+
+        //- Clear the receive buffer on termination (in the destructor)
         const bool clearAtEnd_;
 
-        int messageSize_;
+        //- Reference to the receive buffer data
+        DynamicList<char>& recvBuf_;
+
+        //- Reference to the receive position in buffer data
+        label& recvBufPos_;
 
 
     // Protected Constructors
@@ -120,10 +131,17 @@ protected:
         //- Construct given buffers
         UIPstreamBase(const int fromProcNo, PstreamBuffers& buffers);
 
+        //- Construct for an externally obtained buffer.
+        //  The parameter is allowed to be const (since reading will not
+        //  affect it), but must reference a concrete variable.
+        UIPstreamBase
+        (
+            const DynamicList<char>& receiveBuf,
+            IOstreamOption::streamFormat fmt
+        );
 
 public:
 
-
     //- Destructor. Optionally clears external receive buffer.
     virtual ~UIPstreamBase();
 
@@ -238,6 +256,16 @@ public:
         //- Construct given buffers
         UIPstream(const int fromProcNo, PstreamBuffers& buffers);
 
+        //- Construct for reading from a standalone buffer that has
+        //- been obtained externally by the caller.
+        //  The parameter is allowed to be const (since reading will not
+        //  affect it), but must reference a concrete variable.
+        explicit UIPstream
+        (
+            const DynamicList<char>& recvBuf,
+            IOstreamOption::streamFormat fmt = IOstreamOption::BINARY
+        );
+
 
     //- Destructor
     virtual ~UIPstream() = default;

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

@@ -159,12 +159,13 @@ Foam::UIPstreamBase::UIPstreamBase
     UPstream(commsType),
     Istream(fmt),
     fromProcNo_(fromProcNo),
-    recvBuf_(receiveBuf),
-    recvBufPos_(receiveBufPosition),
     tag_(tag),
     comm_(comm),
+    messageSize_(0),
+    storedRecvBufPos_(0),
     clearAtEnd_(clearAtEnd),
-    messageSize_(0)
+    recvBuf_(receiveBuf),
+    recvBufPos_(receiveBufPosition)
 {
     setOpened();
     setGood();
@@ -180,12 +181,13 @@ Foam::UIPstreamBase::UIPstreamBase
     UPstream(buffers.commsType()),
     Istream(buffers.format()),
     fromProcNo_(fromProcNo),
-    recvBuf_(buffers.accessRecvBuffer(fromProcNo)),
-    recvBufPos_(buffers.accessRecvPosition(fromProcNo)),
     tag_(buffers.tag()),
     comm_(buffers.comm()),
+    messageSize_(0),
+    storedRecvBufPos_(0),
     clearAtEnd_(buffers.allowClearRecv()),
-    messageSize_(0)
+    recvBuf_(buffers.accessRecvBuffer(fromProcNo)),
+    recvBufPos_(buffers.accessRecvPosition(fromProcNo))
 {
     if
     (
@@ -205,6 +207,32 @@ Foam::UIPstreamBase::UIPstreamBase
 }
 
 
+Foam::UIPstreamBase::UIPstreamBase
+(
+    const DynamicList<char>& receiveBuf,
+    IOstreamOption::streamFormat fmt
+)
+:
+    UPstream(UPstream::commsTypes::nonBlocking), // placeholder
+    Istream(fmt),
+    fromProcNo_(UPstream::masterNo()),      // placeholder
+    tag_(UPstream::msgType()),              // placeholder
+    comm_(UPstream::selfComm),              // placeholder
+    messageSize_(receiveBuf.size()),        // Message == buffer
+    storedRecvBufPos_(0),
+    clearAtEnd_(false),   // Do not clear recvBuf if at end!!
+    recvBuf_
+    (
+        // The receive buffer is never modified with this code path
+        const_cast<DynamicList<char>&>(receiveBuf)
+    ),
+    recvBufPos_(storedRecvBufPos_)          // Internal reference
+{
+    setOpened();
+    setGood();
+}
+
+
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
 Foam::UIPstreamBase::~UIPstreamBase()
@@ -517,8 +545,7 @@ void Foam::UIPstreamBase::print(Ostream& os) const
 {
     os  << "Reading from processor " << fromProcNo_
         << " using communicator " << comm_
-        <<  " and tag " << tag_
-        << Foam::endl;
+        <<  " and tag " << tag_ << Foam::endl;
 }
 
 

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

@@ -92,16 +92,21 @@ protected:
 
     // Protected Data
 
-        int toProcNo_;
-
-        DynamicList<char>& sendBuf_;
+        //- Destination rank for the data
+        const int toProcNo_;
 
+        //- Message tag for communication
         const int tag_;
 
-        const label comm_;
+        //- The communicator index
+        const int comm_;
 
+        //- Call bufferIPCsend on termination (in the destructor)
         const bool sendAtDestruct_;
 
+        //- Reference to the send buffer data
+        DynamicList<char>& sendBuf_;
+
 
     // Protected Constructors
 
@@ -122,6 +127,12 @@ protected:
         //- Construct given buffers
         UOPstreamBase(const int toProcNo, PstreamBuffers& buffers);
 
+        //- Construct for externally obtained buffers
+        UOPstreamBase
+        (
+            DynamicList<char>& sendBuf,
+            IOstreamOption::streamFormat fmt
+        );
 
 public:
 
@@ -310,6 +321,14 @@ public:
         //- Construct given buffers
         UOPstream(const int toProcNo, PstreamBuffers& buffers);
 
+        //- Construct for writing into a standalone buffer.
+        //- Data transfer is handled externally by the caller.
+        explicit UOPstream
+        (
+            DynamicList<char>& sendBuf,
+            IOstreamOption::streamFormat fmt = IOstreamOption::BINARY
+        );
+
 
     //- Destructor, usually sends buffer on destruct.
     virtual ~UOPstream();

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

@@ -145,10 +145,10 @@ Foam::UOPstreamBase::UOPstreamBase
     UPstream(commsType),
     Ostream(fmt),
     toProcNo_(toProcNo),
-    sendBuf_(sendBuf),
     tag_(tag),
     comm_(comm),
-    sendAtDestruct_(sendAtDestruct)
+    sendAtDestruct_(sendAtDestruct),
+    sendBuf_(sendBuf)
 {
     setOpened();
     setGood();
@@ -160,16 +160,36 @@ Foam::UOPstreamBase::UOPstreamBase(const int toProcNo, PstreamBuffers& buffers)
     UPstream(buffers.commsType()),
     Ostream(buffers.format()),
     toProcNo_(toProcNo),
-    sendBuf_(buffers.accessSendBuffer(toProcNo)),
     tag_(buffers.tag()),
     comm_(buffers.comm()),
-    sendAtDestruct_(buffers.commsType() != UPstream::commsTypes::nonBlocking)
+    sendAtDestruct_(buffers.commsType() != UPstream::commsTypes::nonBlocking),
+    sendBuf_(buffers.accessSendBuffer(toProcNo))
 {
     setOpened();
     setGood();
 }
 
 
+Foam::UOPstreamBase::UOPstreamBase
+(
+    DynamicList<char>& sendBuf,
+    IOstreamOption::streamFormat fmt
+)
+:
+    UPstream(UPstream::commsTypes::nonBlocking), // placeholder
+    Ostream(fmt),
+    toProcNo_(UPstream::masterNo()),        // placeholder
+    tag_(UPstream::msgType()),              // placeholder
+    comm_(UPstream::selfComm),              // placeholder
+    sendAtDestruct_(false),   // Never sendAtDestruct!!
+    sendBuf_(sendBuf)
+{
+    sendBuf_.clear();  // Overwrite into buffer
+    setOpened();
+    setGood();
+}
+
+
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
 Foam::UOPstreamBase::~UOPstreamBase()
@@ -394,8 +414,8 @@ void Foam::UOPstreamBase::rewind()
 
 void Foam::UOPstreamBase::print(Ostream& os) const
 {
-    os  << "Writing from processor " << toProcNo_
-        << " to processor " << myProcNo() << " in communicator " << comm_
+    os  << "Writing to processor " << toProcNo_
+        << " from processor " << myProcNo() << " in communicator " << comm_
         << " and tag " << tag_ << Foam::endl;
 }