UIPBstreamRead.C

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/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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     \\/     M anipulation  |
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    Copyright (C) 2022-2024 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
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#include "UIPstream.H"
#include "PstreamGlobals.H"
#include "IOstreams.H"

// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //

void Foam::UIPBstream::bufferIPCrecv()
{
    // Uses double broadcast. Symmetric with UOPBstream::bufferIPCsend()
    // 1. for the data size
    // 2. for the data itself

    // Expected message size, similar to MPI_Probe
    // Same type must be expected in UOPBstream::bufferIPCsend()
    std::streamsize bufSize(0);

    // Broadcast #1 - data size
    if
    (
        !UPstream::broadcast
        (
            reinterpret_cast<char*>(&bufSize),
            sizeof(std::streamsize),
            comm_,
            fromProcNo_  //< is actually rootProcNo
        )
    )
    {
        FatalErrorInFunction
            << "MPI_Bcast failure receiving buffer size" << nl
            << Foam::abort(FatalError);
    }

    if (UPstream::debug)
    {
        Perr<< "UOPBstream IPC read buffer :"
            << " root:" << fromProcNo_
            << " comm:" << comm_
            << " probed size:" << label(bufSize)
            << " wanted size:" << recvBuf_.capacity()
            << Foam::endl;
    }


    // Set buffer size, avoiding any copying and resize doubling etc.
    recvBuf_.clear();
    if (recvBuf_.capacity() < label(bufSize))
    {
        recvBuf_.setCapacity_nocopy(label(bufSize));
    }
    recvBuf_.resize_nocopy(label(bufSize));

    // This is the only real information we can trust
    messageSize_ = label(bufSize);


    // Broadcast #2 - data content
    // - skip if there is no data to receive
    if
    (
        (bufSize > 0)
     && !UPstream::broadcast
        (
            recvBuf_.data(),
            recvBuf_.size(),  // same as bufSize
            comm_,
            fromProcNo_  //< is actually rootProcNo
        )
    )
    {
        FatalErrorInFunction
            << "MPI_Bcast failure receiving buffer data:"
            << recvBuf_.size() << nl
            << Foam::abort(FatalError);
    }

    if (recvBuf_.empty())
    {
        setEof();
    }
}


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

std::streamsize Foam::UIPBstream::read
(
    const int rootProcNo,
    char* buf,
    const std::streamsize bufSize,
    const label comm
)
{
    if
    (
        !UPstream::broadcast(buf, bufSize, comm, rootProcNo)
    )
    {
        FatalErrorInFunction
            << "MPI_Bcast failure receiving data:" << label(bufSize) << nl
            << Foam::abort(FatalError);
        return 0;
    }

    return bufSize;
}


// ************************************************************************* //