/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2013 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
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 "mpi.h"

#include "UPstream.H"
#include "PstreamReduceOps.H"
#include "OSspecific.H"
#include "PstreamGlobals.H"
#include "SubList.H"
#include "allReduce.H"

#include <cstring>
#include <cstdlib>
#include <csignal>

#if defined(WM_SP)
#   define MPI_SCALAR MPI_FLOAT
#elif defined(WM_DP)
#   define MPI_SCALAR MPI_DOUBLE
#endif

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

// NOTE:
// valid parallel options vary between implementations, but flag common ones.
// if they are not removed by MPI_Init(), the subsequent argument processing
// will notice that they are wrong
void Foam::UPstream::addValidParOptions(HashTable<string>& validParOptions)
{
    validParOptions.insert("np", "");
    validParOptions.insert("p4pg", "PI file");
    validParOptions.insert("p4wd", "directory");
    validParOptions.insert("p4amslave", "");
    validParOptions.insert("p4yourname", "hostname");
    validParOptions.insert("machinefile", "machine file");
}


bool Foam::UPstream::init(int& argc, char**& argv)
{
    MPI_Init(&argc, &argv);

    int numprocs;
    MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
    int myRank;
    MPI_Comm_rank(MPI_COMM_WORLD, &myRank);

    if (debug&1)
    {
        Pout<< "UPstream::init : initialised with numProcs:" << numprocs
            << " myRank:" << myRank << endl;
    }

    if (numprocs <= 1)
    {
        FatalErrorIn("UPstream::init(int& argc, char**& argv)")
            << "bool IPstream::init(int& argc, char**& argv) : "
               "attempt to run parallel on 1 processor"
            << Foam::abort(FatalError);
    }


    // Initialise parallel structure
    setParRun(numprocs);

#   ifndef SGIMPI
    string bufferSizeName = getEnv("MPI_BUFFER_SIZE");

    if (bufferSizeName.size())
    {
        int bufferSize = atoi(bufferSizeName.c_str());

        if (bufferSize)
        {
            MPI_Buffer_attach(new char[bufferSize], bufferSize);
        }
    }
    else
    {
        FatalErrorIn("UPstream::init(int& argc, char**& argv)")
            << "UPstream::init(int& argc, char**& argv) : "
            << "environment variable MPI_BUFFER_SIZE not defined"
            << Foam::abort(FatalError);
    }
#   endif

    //int processorNameLen;
    //char processorName[MPI_MAX_PROCESSOR_NAME];
    //
    //MPI_Get_processor_name(processorName, &processorNameLen);
    //processorName[processorNameLen] = '\0';
    //Pout<< "Processor name:" << processorName << endl;

    return true;
}


void Foam::UPstream::exit(int errnum)
{
    if (debug&1)
    {
        Pout<< "UPstream::exit." << endl;
    }

#   ifndef SGIMPI
    int size;
    char* buff;
    MPI_Buffer_detach(&buff, &size);
    delete[] buff;
#   endif

    if (PstreamGlobals::outstandingRequests_.size())
    {
        label n = PstreamGlobals::outstandingRequests_.size();
        PstreamGlobals::outstandingRequests_.clear();

        WarningIn("UPstream::exit(int)")
            << "There are still " << n << " outstanding MPI_Requests." << endl
            << "This means that your code exited before doing a"
            << " UPstream::waitRequests()." << endl
            << "This should not happen for a normal code exit."
            << endl;
    }

    // Clean mpi communicators
    forAll(myProcNo_, communicator)
    {
        if (myProcNo_[communicator] != -1)
        {
            freePstreamCommunicator(communicator);
        }
    }

    if (errnum == 0)
    {
        MPI_Finalize();
        ::exit(errnum);
    }
    else
    {
        MPI_Abort(MPI_COMM_WORLD, errnum);
    }
}


void Foam::UPstream::abort()
{
    MPI_Abort(MPI_COMM_WORLD, 1);
}


void Foam::reduce
(
    scalar& Value,
    const sumOp<scalar>& bop,
    const int tag,
    const label communicator
)
{
    if (UPstream::warnComm != -1 && communicator != UPstream::warnComm)
    {
        Pout<< "** reducing:" << Value << " with comm:" << communicator
            << endl;
        error::printStack(Pout);
    }
    allReduce(Value, 1, MPI_SCALAR, MPI_SUM, bop, tag, communicator);
}


void Foam::reduce
(
    scalar& Value,
    const minOp<scalar>& bop,
    const int tag,
    const label communicator
)
{
    if (UPstream::warnComm != -1 && communicator != UPstream::warnComm)
    {
        Pout<< "** reducing:" << Value << " with comm:" << communicator
            << endl;
        error::printStack(Pout);
    }
    allReduce(Value, 1, MPI_SCALAR, MPI_MIN, bop, tag, communicator);
}


void Foam::reduce
(
    vector2D& Value,
    const sumOp<vector2D>& bop,
    const int tag,
    const label communicator
)
{
    if (UPstream::warnComm != -1 && communicator != UPstream::warnComm)
    {
        Pout<< "** reducing:" << Value << " with comm:" << communicator
            << endl;
        error::printStack(Pout);
    }
    allReduce(Value, 2, MPI_SCALAR, MPI_SUM, bop, tag, communicator);
}


void Foam::sumReduce
(
    scalar& Value,
    label& Count,
    const int tag,
    const label communicator
)
{
    if (UPstream::warnComm != -1 && communicator != UPstream::warnComm)
    {
        Pout<< "** reducing:" << Value << " with comm:" << communicator
            << endl;
        error::printStack(Pout);
    }
    vector2D twoScalars(Value, scalar(Count));
    reduce(twoScalars, sumOp<vector2D>(), tag, communicator);

    Value = twoScalars.x();
    Count = twoScalars.y();
}


void Foam::reduce
(
    scalar& Value,
    const sumOp<scalar>& bop,
    const int tag,
    const label communicator,
    label& requestID
)
{
#ifdef MPIX_COMM_TYPE_SHARED
    // Assume mpich2 with non-blocking collectives extensions. Once mpi3
    // is available this will change.
    MPI_Request request;
    scalar v = Value;
    MPIX_Ireduce
    (
        &v,
        &Value,
        1,
        MPI_SCALAR,
        MPI_SUM,
        0,              //root
        PstreamGlobals::MPICommunicators_[communicator],
        &request
    );

    requestID = PstreamGlobals::outstandingRequests_.size();
    PstreamGlobals::outstandingRequests_.append(request);
#else
    // Non-blocking not yet implemented in mpi
    reduce(Value, bop, tag, communicator);
    requestID = -1;
#endif
}


void Foam::UPstream::allocatePstreamCommunicator
(
    const label parentIndex,
    const label index
)
{
    if (index == PstreamGlobals::MPIGroups_.size())
    {
        // Extend storage with dummy values
        MPI_Group newGroup;
        PstreamGlobals::MPIGroups_.append(newGroup);
        MPI_Comm newComm;
        PstreamGlobals::MPICommunicators_.append(newComm);
    }
    else if (index > PstreamGlobals::MPIGroups_.size())
    {
        FatalErrorIn
        (
            "UPstream::allocatePstreamCommunicator\n"
            "(\n"
            "    const label parentIndex,\n"
            "    const labelList& subRanks\n"
            ")\n"
        )   << "PstreamGlobals out of sync with UPstream data. Problem."
            << Foam::exit(FatalError);
    }


    if (parentIndex == -1)
    {
        // Allocate world communicator

        //std::cout
        //    << "MPI : Allocating world communicator at index " << index
        //    << std::endl;

        if (index != UPstream::worldComm)
        {
            FatalErrorIn
            (
                "UPstream::allocateCommunicator\n"
                "(\n"
                "    const label parentIndex,\n"
                "    const labelList& subRanks\n"
                ")\n"
            )   << "world communicator should always be index "
                << UPstream::worldComm << Foam::exit(FatalError);
        }

        PstreamGlobals::MPICommunicators_[index] = MPI_COMM_WORLD;
        MPI_Comm_group(MPI_COMM_WORLD, &PstreamGlobals::MPIGroups_[index]);
        MPI_Comm_rank
        (
            PstreamGlobals::MPICommunicators_[index],
           &myProcNo_[index]
        );

        // Set the number of processes to the actual number
        int numProcs;
        MPI_Comm_size(PstreamGlobals::MPICommunicators_[index], &numProcs);
        procIDs_[index] = identity(numProcs);
    }
    else
    {
        //std::cout
        //    << "MPI : Allocating new communicator at index " << index
        //    << " from parent " << parentIndex
        //    << std::endl;

        // Create new group
        MPI_Group_incl
        (
            PstreamGlobals::MPIGroups_[parentIndex],
            procIDs_[index].size(),
            procIDs_[index].begin(),
           &PstreamGlobals::MPIGroups_[index]
        );
 
       //std::cout
       //     << "MPI : New group " << long(PstreamGlobals::MPIGroups_[index])
       //     << std::endl;


        // Create new communicator
        MPI_Comm_create
        (
            PstreamGlobals::MPICommunicators_[parentIndex],
            PstreamGlobals::MPIGroups_[index],
           &PstreamGlobals::MPICommunicators_[index]
        );

        if (PstreamGlobals::MPICommunicators_[index] == MPI_COMM_NULL)
        {
            //std::cout
            //     << "MPI : NULL : not in group"
            //    << std::endl;
            myProcNo_[index] = -1;
        }
        else
        {
            //std::cout
            //    << "MPI : New comm "
            //    << long(PstreamGlobals::MPICommunicators_[index])
            //    << std::endl;
            MPI_Comm_rank
            (
                PstreamGlobals::MPICommunicators_[index],
               &myProcNo_[index]
            );
        }
    }

    //std::cout<< "MPI : I am rank " << myProcNo_[index] << std::endl;
}


void Foam::UPstream::freePstreamCommunicator(const label communicator)
{
    if (communicator != UPstream::worldComm)
    {
        if (PstreamGlobals::MPICommunicators_[communicator] != MPI_COMM_NULL)
        {
            MPI_Comm_free(&PstreamGlobals::MPICommunicators_[communicator]);
        }
        MPI_Group_free(&PstreamGlobals::MPIGroups_[communicator]);
    }
}


Foam::label Foam::UPstream::nRequests()
{
    return PstreamGlobals::outstandingRequests_.size();
}


void Foam::UPstream::resetRequests(const label i)
{
    if (i < PstreamGlobals::outstandingRequests_.size())
    {
        PstreamGlobals::outstandingRequests_.setSize(i);
    }
}


void Foam::UPstream::waitRequests(const label start)
{
    if (debug&1)
    {
        Pout<< "UPstream::waitRequests : starting wait for "
            << PstreamGlobals::outstandingRequests_.size()-start
            << " outstanding requests starting at " << start << endl;
    }

    if (PstreamGlobals::outstandingRequests_.size())
    {
        SubList<MPI_Request> waitRequests
        (
            PstreamGlobals::outstandingRequests_,
            PstreamGlobals::outstandingRequests_.size() - start,
            start
        );

        if
        (
            MPI_Waitall
            (
                waitRequests.size(),
                waitRequests.begin(),
                MPI_STATUSES_IGNORE
            )
        )
        {
            FatalErrorIn
            (
                "UPstream::waitRequests()"
            )   << "MPI_Waitall returned with error" << Foam::endl;
        }

        resetRequests(start);
    }

    if (debug&1)
    {
        Pout<< "UPstream::waitRequests : finished wait." << endl;
    }
}


void Foam::UPstream::waitRequest(const label i)
{
    if (debug&1)
    {
        Pout<< "UPstream::waitRequest : starting wait for request:" << i
            << endl;
    }

    if (i >= PstreamGlobals::outstandingRequests_.size())
    {
        FatalErrorIn
        (
            "UPstream::waitRequest(const label)"
        )   << "There are " << PstreamGlobals::outstandingRequests_.size()
            << " outstanding send requests and you are asking for i=" << i
            << nl
            << "Maybe you are mixing blocking/non-blocking comms?"
            << Foam::abort(FatalError);
    }

    if
    (
        MPI_Wait
        (
           &PstreamGlobals::outstandingRequests_[i],
            MPI_STATUS_IGNORE
        )
    )
    {
        FatalErrorIn
        (
            "UPstream::waitRequest()"
        )   << "MPI_Wait returned with error" << Foam::endl;
    }

    if (debug&1)
    {
        Pout<< "UPstream::waitRequest : finished wait for request:" << i
            << endl;
    }
}


bool Foam::UPstream::finishedRequest(const label i)
{
    if (debug&1)
    {
        Pout<< "UPstream::waitRequests : checking finishedRequest:" << i
            << endl;
    }

    if (i >= PstreamGlobals::outstandingRequests_.size())
    {
        FatalErrorIn
        (
            "UPstream::finishedRequest(const label)"
        )   << "There are " << PstreamGlobals::outstandingRequests_.size()
            << " outstanding send requests and you are asking for i=" << i
            << nl
            << "Maybe you are mixing blocking/non-blocking comms?"
            << Foam::abort(FatalError);
    }

    int flag;
    MPI_Test
    (
       &PstreamGlobals::outstandingRequests_[i],
       &flag,
        MPI_STATUS_IGNORE
    );

    if (debug&1)
    {
        Pout<< "UPstream::waitRequests : finished finishedRequest:" << i
            << endl;
    }

    return flag != 0;
}


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