Comm.h

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///////////////////////////////////////////////////////////////////////////////
//
// File: Comm.h
//
// For more information, please see: http://www.nektar.info
//
// The MIT License
//
// Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
// Department of Aeronautics, Imperial College London (UK), and Scientific
// Computing and Imaging Institute, University of Utah (USA).
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// Description: Base communication class
//
///////////////////////////////////////////////////////////////////////////////
#ifndef NEKTAR_LIB_UTILITIES_COMM_H
#define NEKTAR_LIB_UTILITIES_COMM_H
 
#include <memory>
#include <type_traits>
#include <utility>
#include <vector>
 
#include <LibUtilities/BasicUtils/NekFactory.hpp>
#include <LibUtilities/LibUtilitiesDeclspec.h>
 
#include <LibUtilities/BasicConst/NektarUnivTypeDefs.hpp>
#include <LibUtilities/BasicUtils/SharedArray.hpp>
#include <LibUtilities/Communication/CommDataType.h>
 
namespace Nektar::LibUtilities
{
// Forward declarations
class Comm;
 
/// Pointer to a Communicator object.
typedef std::shared_ptr<Comm> CommSharedPtr;
 
/// Datatype of the NekFactory used to instantiate classes derived from
/// the EquationSystem class.
typedef LibUtilities::NekFactory<std::string, Comm, int, char **> CommFactory;
 
LIB_UTILITIES_EXPORT CommFactory &GetCommFactory();
 
/// Type of operation to perform in AllReduce.
enum ReduceOperator
{
    ReduceSum,
    ReduceMax,
    ReduceMin,
    SIZE_ReduceOperator
};
 
const char *const ReduceOperatorMap[] = {"ReduceSum", "ReduceMax", "ReduceMin"};
 
/// Class for communicator request type
class CommRequest
{
public:
    /// Default constructor
    CommRequest() = default;
    /// Default destructor
    virtual ~CommRequest() = default;
};
 
typedef std::shared_ptr<CommRequest> CommRequestSharedPtr;
 
/// Base communications class
class Comm : public std::enable_shared_from_this<Comm>
{
public:
    LIB_UTILITIES_EXPORT Comm(int narg, char *arg[]);
    LIB_UTILITIES_EXPORT virtual ~Comm();
 
    LIB_UTILITIES_EXPORT inline void Finalise();
 
    /// Returns number of processes
    LIB_UTILITIES_EXPORT inline int GetSize() const;
    LIB_UTILITIES_EXPORT inline int GetRank();
    LIB_UTILITIES_EXPORT inline const std::string &GetType() const;
 
    LIB_UTILITIES_EXPORT inline bool TreatAsRankZero();
    LIB_UTILITIES_EXPORT inline bool IsSerial();
    LIB_UTILITIES_EXPORT inline bool IsParallelInTime();
    LIB_UTILITIES_EXPORT inline std::tuple<int, int, int> GetVersion();
 
    /// Block execution until all processes reach this point
    LIB_UTILITIES_EXPORT inline void Block();
 
    /// Return the time in seconds
    LIB_UTILITIES_EXPORT inline NekDouble Wtime();
 
    template <class T> void Send(int pProc, T &pData);
    template <class T> void Recv(int pProc, T &pData);
    template <class T>
    void SendRecv(int pSendProc, T &pSendData, int pRecvProc, T &pRecvData);
 
    template <class T> void AllReduce(T &pData, enum ReduceOperator pOp);
 
    template <class T> void AlltoAll(T &pSendData, T &pRecvData);
    template <class T1, class T2>
    void AlltoAllv(T1 &pSendData, T2 &pSendDataSizeMap, T2 &pSendDataOffsetMap,
                   T1 &pRecvData, T2 &pRecvDataSizeMap, T2 &pRecvDataOffsetMap);
 
    template <class T> void AllGather(T &pSendData, T &pRecvData);
    template <class T>
    void AllGatherv(T &pSendData, T &pRecvData,
                    Array<OneD, int> &pRecvDataSizeMap,
                    Array<OneD, int> &pRecvDataOffsetMap);
    template <class T>
    void AllGatherv(T &pRecvData, Array<OneD, int> &pRecvDataSizeMap,
                    Array<OneD, int> &pRecvDataOffsetMap);
 
    template <class T> void Bcast(T &pData, int pRoot);
    template <class T> T Gather(int rootProc, T &val);
    template <class T> T Scatter(int rootProc, T &pData);
 
    template <class T>
    void DistGraphCreateAdjacent(T &sources, T &sourceweights, int reorder);
    template <class T1, class T2>
    void NeighborAlltoAllv(T1 &pSendData, T2 &pSendDataSizeMap,
                           T2 &pSendDataOffsetMap, T1 &pRecvData,
                           T2 &pRecvDataSizeMap, T2 &pRecvDataOffsetMap);
 
    template <class T>
    void Irsend(int pProc, T &pData, int count,
                const CommRequestSharedPtr &request, int loc);
    template <class T>
    void Isend(int pProc, T &pData, int count,
               const CommRequestSharedPtr &request, int loc);
    template <class T>
    void SendInit(int pProc, T &pData, int count,
                  const CommRequestSharedPtr &request, int loc);
    template <class T>
    void Irecv(int pProc, T &pData, int count,
               const CommRequestSharedPtr &request, int loc);
    template <class T>
    void RecvInit(int pProc, T &pData, int count,
                  const CommRequestSharedPtr &request, int loc);
 
    inline void StartAll(const CommRequestSharedPtr &request);
    inline void WaitAll(const CommRequestSharedPtr &request);
 
    inline CommRequestSharedPtr CreateRequest(int num);
    LIB_UTILITIES_EXPORT inline CommSharedPtr CommCreateIf(int flag);
    LIB_UTILITIES_EXPORT inline void SplitComm(int pRows, int pColumns,
                                               int pTime = 1);
    LIB_UTILITIES_EXPORT inline CommSharedPtr GetRowComm();
    LIB_UTILITIES_EXPORT inline CommSharedPtr GetColumnComm();
    LIB_UTILITIES_EXPORT inline CommSharedPtr GetTimeComm();
    LIB_UTILITIES_EXPORT inline CommSharedPtr GetSpaceComm();
    LIB_UTILITIES_EXPORT inline bool RemoveExistingFiles();
    LIB_UTILITIES_EXPORT inline std::pair<CommSharedPtr, CommSharedPtr>
    SplitCommNode();
 
protected:
    int m_size;                 ///< Number of processes
    std::string m_type;         ///< Type of communication
    CommSharedPtr m_commRow;    ///< Row communicator
    CommSharedPtr m_commColumn; ///< Column communicator
    CommSharedPtr m_commTime;
    CommSharedPtr m_commSpace;
 
    Comm();
 
    virtual void v_Finalise()                                              = 0;
    virtual int v_GetRank()                                                = 0;
    virtual bool v_TreatAsRankZero()                                       = 0;
    virtual bool v_IsSerial()                                              = 0;
    virtual std::tuple<int, int, int> v_GetVersion()                       = 0;
    virtual void v_Block()                                                 = 0;
    virtual NekDouble v_Wtime()                                            = 0;
    virtual void v_Send(void *buf, int count, CommDataType dt, int dest)   = 0;
    virtual void v_Recv(void *buf, int count, CommDataType dt, int source) = 0;
    virtual void v_SendRecv(void *sendbuf, int sendcount, CommDataType sendtype,
                            int dest, void *recvbuf, int recvcount,
                            CommDataType recvtype, int source)             = 0;
    virtual void v_AllReduce(void *buf, int count, CommDataType dt,
                             enum ReduceOperator pOp)                      = 0;
    virtual void v_AlltoAll(void *sendbuf, int sendcount, CommDataType sendtype,
                            void *recvbuf, int recvcount,
                            CommDataType recvtype)                         = 0;
    virtual void v_AlltoAllv(void *sendbuf, int sendcounts[], int sensdispls[],
                             CommDataType sendtype, void *recvbuf,
                             int recvcounts[], int rdispls[],
                             CommDataType recvtype)                        = 0;
    virtual void v_AllGather(void *sendbuf, int sendcount,
                             CommDataType sendtype, void *recvbuf,
                             int recvcount, CommDataType recvtype)         = 0;
    virtual void v_AllGatherv(void *sendbuf, int sendcount,
                              CommDataType sendtype, void *recvbuf,
                              int recvcounts[], int rdispls[],
                              CommDataType recvtype)                       = 0;
    virtual void v_AllGatherv(void *recvbuf, int recvcounts[], int rdispls[],
                              CommDataType recvtype)                       = 0;
    virtual void v_Bcast(void *buffer, int count, CommDataType dt,
                         int root)                                         = 0;
    virtual void v_Gather(void *sendbuf, int sendcount, CommDataType sendtype,
                          void *recvbuf, int recvcount, CommDataType recvtype,
                          int root)                                        = 0;
    virtual void v_Scatter(void *sendbuf, int sendcount, CommDataType sendtype,
                           void *recvbuf, int recvcount, CommDataType recvtype,
                           int root)                                       = 0;
 
    virtual void v_DistGraphCreateAdjacent(int indegree, const int sources[],
                                           const int sourceweights[],
                                           int reorder) = 0;
 
    virtual void v_NeighborAlltoAllv(void *sendbuf, int sendcounts[],
                                     int sdispls[], CommDataType sendtype,
                                     void *recvbuf, int recvcounts[],
                                     int rdispls[], CommDataType recvtype) = 0;
 
    virtual void v_Irsend(void *buf, int count, CommDataType dt, int dest,
                          CommRequestSharedPtr request, int loc)   = 0;
    virtual void v_Isend(void *buf, int count, CommDataType dt, int dest,
                         CommRequestSharedPtr request, int loc)    = 0;
    virtual void v_SendInit(void *buf, int count, CommDataType dt, int dest,
                            CommRequestSharedPtr request, int loc) = 0;
    virtual void v_Irecv(void *buf, int count, CommDataType dt, int source,
                         CommRequestSharedPtr request, int loc)    = 0;
    virtual void v_RecvInit(void *buf, int count, CommDataType dt, int source,
                            CommRequestSharedPtr request, int loc) = 0;
    virtual void v_StartAll(CommRequestSharedPtr request)          = 0;
    virtual void v_WaitAll(CommRequestSharedPtr request)           = 0;
    virtual CommRequestSharedPtr v_CreateRequest(int num)          = 0;
 
    virtual void v_SplitComm(int pRows, int pColumns, int pTime) = 0;
 
    virtual CommSharedPtr v_CommCreateIf(int flag) = 0;
    LIB_UTILITIES_EXPORT virtual std::pair<CommSharedPtr, CommSharedPtr>
    v_SplitCommNode();
};
 
/**
 *
 */
inline void Comm::Finalise()
{
    v_Finalise();
}
 
/**
 *
 */
inline int Comm::GetSize() const
{
    return m_size;
}
 
/**
 *
 */
inline int Comm::GetRank()
{
    return v_GetRank();
}
 
/**
 *
 */
inline const std::string &Comm::GetType() const
{
    return m_type;
}
 
/**
 *
 */
inline bool Comm::TreatAsRankZero()
{
    return v_TreatAsRankZero();
}
 
/**
 *
 */
inline bool Comm::IsSerial()
{
    return v_IsSerial();
}
 
/**
 *
 */
inline bool Comm::IsParallelInTime()
{
    return m_commTime.get();
}
 
/**
 * @return tuple of {major, minor, patch} version numbers
 */
inline std::tuple<int, int, int> Comm::GetVersion()
{
    return v_GetVersion();
}
 
/**
 *
 */
inline void Comm::Block()
{
    v_Block();
}
 
/**
 *
 */
inline double Comm::Wtime()
{
    return v_Wtime();
}
 
/**
 *
 */
template <class T> void Comm::Send(int pProc, T &pData)
{
    v_Send(CommDataTypeTraits<T>::GetPointer(pData),
           CommDataTypeTraits<T>::GetCount(pData),
           CommDataTypeTraits<T>::GetDataType(), pProc);
}
 
/**
 *
 */
template <class T> void Comm::Recv(int pProc, T &pData)
{
    v_Recv(CommDataTypeTraits<T>::GetPointer(pData),
           CommDataTypeTraits<T>::GetCount(pData),
           CommDataTypeTraits<T>::GetDataType(), pProc);
}
 
/**
 *
 */
template <class T>
void Comm::SendRecv(int pSendProc, T &pSendData, int pRecvProc, T &pRecvData)
{
    v_SendRecv(CommDataTypeTraits<T>::GetPointer(pSendData),
               CommDataTypeTraits<T>::GetCount(pSendData),
               CommDataTypeTraits<T>::GetDataType(), pSendProc,
               CommDataTypeTraits<T>::GetPointer(pRecvData),
               CommDataTypeTraits<T>::GetCount(pRecvData),
               CommDataTypeTraits<T>::GetDataType(), pRecvProc);
}
 
/**
 *
 */
template <class T> void Comm::AllReduce(T &pData, enum ReduceOperator pOp)
{
    v_AllReduce(CommDataTypeTraits<T>::GetPointer(pData),
                CommDataTypeTraits<T>::GetCount(pData),
                CommDataTypeTraits<T>::GetDataType(), pOp);
}
 
/**
 *
 */
template <class T> void Comm::AlltoAll(T &pSendData, T &pRecvData)
{
    static_assert(CommDataTypeTraits<T>::IsVector,
                  "AlltoAll only valid with Array or vector arguments.");
    int sendSize = CommDataTypeTraits<T>::GetCount(pSendData);
    int recvSize = CommDataTypeTraits<T>::GetCount(pRecvData);
    ASSERTL0(sendSize == recvSize,
             "Send and Recv arrays have incompatible sizes in AlltoAll");
 
    int count = sendSize / GetSize();
    ASSERTL0(count * GetSize() == sendSize,
             "Array size incompatible with size of communicator");
 
    v_AlltoAll(CommDataTypeTraits<T>::GetPointer(pSendData), count,
               CommDataTypeTraits<T>::GetDataType(),
               CommDataTypeTraits<T>::GetPointer(pRecvData), count,
               CommDataTypeTraits<T>::GetDataType());
}
 
/**
 *
 */
template <class T1, class T2>
void Comm::AlltoAllv(T1 &pSendData, T2 &pSendDataSizeMap,
                     T2 &pSendDataOffsetMap, T1 &pRecvData,
                     T2 &pRecvDataSizeMap, T2 &pRecvDataOffsetMap)
{
    static_assert(CommDataTypeTraits<T1>::IsVector,
                  "AlltoAllv only valid with Array or vector arguments.");
    static_assert(std::is_same<T2, std::vector<int>>::value ||
                      std::is_same<T2, Array<OneD, int>>::value,
                  "Alltoallv size and offset maps should be integer vectors.");
    v_AlltoAllv(CommDataTypeTraits<T1>::GetPointer(pSendData),
                (int *)CommDataTypeTraits<T2>::GetPointer(pSendDataSizeMap),
                (int *)CommDataTypeTraits<T2>::GetPointer(pSendDataOffsetMap),
                CommDataTypeTraits<T1>::GetDataType(),
                CommDataTypeTraits<T1>::GetPointer(pRecvData),
                (int *)CommDataTypeTraits<T2>::GetPointer(pRecvDataSizeMap),
                (int *)CommDataTypeTraits<T2>::GetPointer(pRecvDataOffsetMap),
                CommDataTypeTraits<T1>::GetDataType());
}
 
/**
 *
 */
template <class T> void Comm::AllGather(T &pSendData, T &pRecvData)
{
    BOOST_STATIC_ASSERT_MSG(
        CommDataTypeTraits<T>::IsVector,
        "AllGather only valid with Array or vector arguments.");
 
    int sendSize = CommDataTypeTraits<T>::GetCount(pSendData);
    int recvSize = sendSize;
 
    pRecvData = T(recvSize * GetSize());
 
    v_AllGather(CommDataTypeTraits<T>::GetPointer(pSendData), sendSize,
                CommDataTypeTraits<T>::GetDataType(),
                CommDataTypeTraits<T>::GetPointer(pRecvData), recvSize,
                CommDataTypeTraits<T>::GetDataType());
}
 
/**
 *
 */
template <class T>
void Comm::AllGatherv(T &pSendData, T &pRecvData,
                      Array<OneD, int> &pRecvDataSizeMap,
                      Array<OneD, int> &pRecvDataOffsetMap)
{
    BOOST_STATIC_ASSERT_MSG(
        CommDataTypeTraits<T>::IsVector,
        "AllGatherv only valid with Array or vector arguments.");
 
    int sendSize = CommDataTypeTraits<T>::GetCount(pSendData);
 
    v_AllGatherv(CommDataTypeTraits<T>::GetPointer(pSendData), sendSize,
                 CommDataTypeTraits<T>::GetDataType(),
                 CommDataTypeTraits<T>::GetPointer(pRecvData),
                 pRecvDataSizeMap.get(), pRecvDataOffsetMap.get(),
                 CommDataTypeTraits<T>::GetDataType());
}
 
/**
 *
 */
template <class T>
void Comm::AllGatherv(T &pRecvData, Array<OneD, int> &pRecvDataSizeMap,
                      Array<OneD, int> &pRecvDataOffsetMap)
{
    BOOST_STATIC_ASSERT_MSG(
        CommDataTypeTraits<T>::IsVector,
        "AllGatherv only valid with Array or vector arguments.");
 
    v_AllGatherv(CommDataTypeTraits<T>::GetPointer(pRecvData),
                 pRecvDataSizeMap.get(), pRecvDataOffsetMap.get(),
                 CommDataTypeTraits<T>::GetDataType());
}
 
/**
 *
 */
template <class T> void Comm::Bcast(T &pData, int pRoot)
{
    v_Bcast(CommDataTypeTraits<T>::GetPointer(pData),
            CommDataTypeTraits<T>::GetCount(pData),
            CommDataTypeTraits<T>::GetDataType(), pRoot);
}
 
/**
 * Concatenate all the input arrays, in rank order, onto the process with rank
 * == rootProc
 */
template <class T> T Comm::Gather(const int rootProc, T &val)
{
    static_assert(CommDataTypeTraits<T>::IsVector,
                  "Gather only valid with Array or vector arguments.");
    bool amRoot  = (GetRank() == rootProc);
    unsigned nEl = CommDataTypeTraits<T>::GetCount(val);
 
    unsigned nOut = amRoot ? GetSize() * nEl : 0;
    T ans(nOut);
    void *recvbuf = amRoot ? CommDataTypeTraits<T>::GetPointer(ans) : nullptr;
 
    v_Gather(CommDataTypeTraits<T>::GetPointer(val), nEl,
             CommDataTypeTraits<T>::GetDataType(), recvbuf, nEl,
             CommDataTypeTraits<T>::GetDataType(), rootProc);
    return ans;
}
 
/**
 * Scatter pData across ranks in chunks of len(pData)/num_ranks
 */
template <class T> T Comm::Scatter(const int rootProc, T &pData)
{
    static_assert(CommDataTypeTraits<T>::IsVector,
                  "Scatter only valid with Array or vector arguments.");
 
    bool amRoot  = (GetRank() == rootProc);
    unsigned nEl = CommDataTypeTraits<T>::GetCount(pData) / GetSize();
 
    void *sendbuf = amRoot ? CommDataTypeTraits<T>::GetPointer(pData) : nullptr;
    T ans(nEl);
 
    v_Scatter(sendbuf, nEl, CommDataTypeTraits<T>::GetDataType(),
              CommDataTypeTraits<T>::GetPointer(ans), nEl,
              CommDataTypeTraits<T>::GetDataType(), rootProc);
    return ans;
}
 
/**
 * This replaces the current MPI communicator with a new one that also holds
 * the distributed graph topology information. If reordering is enabled using
 * this might break code where process/rank numbers are assumed to remain
 * constant. This also assumes that the graph is bi-directional, so all
 * sources are also destinations with equal weighting.
 *
 * @param sources       Ranks of processes for which the calling process is the
 *                      destination/source
 * @param sourceweights Weights of the corresponding edges into the calling
 *                      process
 * @param reorder       Ranks may be reordered (true) or not (false)
 */
template <class T>
void Comm::DistGraphCreateAdjacent(T &sources, T &sourceweights, int reorder)
{
    static_assert(
        CommDataTypeTraits<T>::IsVector,
        "DistGraphCreateAdjacent only valid with Array or vector arguments.");
 
    ASSERTL0(CommDataTypeTraits<T>::GetCount(sources) ==
                 CommDataTypeTraits<T>::GetCount(sourceweights),
             "Sources and weights array sizes don't match");
 
    int indegree = CommDataTypeTraits<T>::GetCount(sources);
 
    v_DistGraphCreateAdjacent(
        indegree, (const int *)CommDataTypeTraits<T>::GetPointer(sources),
        (const int *)CommDataTypeTraits<T>::GetPointer(sourceweights), reorder);
}
 
/**
 * Sends data to neighboring processes in a virtual topology communicator. All
 * processes send different amounts of data to, and receive different amounts
 * of data from, all neighbors
 *
 * @param pSendData          Array/vector to send to neighbors
 * @param pSendDataSizeMap   Array/vector where entry i specifies the number
 *                           of elements to send to neighbor i
 * @param pSendDataOffsetMap Array/vector where entry i specifies the
 *                           displacement (offset from pSendData) from which to
 *                           send data to neighbor i
 * @param pRecvData          Array/vector to place incoming data in to
 * @param pRecvDataSizeMap   Array/vector where entry i specifies the number
 *                           of elements to receive from neighbor i
 * @param pRecvDataOffsetMap Array/vector where entry i specifies the
 *                           displacement (offset from pRecvData) from which to
 *                           receive data from neighbor i
 */
template <class T1, class T2>
void Comm::NeighborAlltoAllv(T1 &pSendData, T2 &pSendDataSizeMap,
                             T2 &pSendDataOffsetMap, T1 &pRecvData,
                             T2 &pRecvDataSizeMap, T2 &pRecvDataOffsetMap)
{
    static_assert(
        CommDataTypeTraits<T1>::IsVector,
        "NeighbourAlltoAllv only valid with Array or vector arguments.");
    static_assert(
        std::is_same<T2, std::vector<int>>::value ||
            std::is_same<T2, Array<OneD, int>>::value,
        "NeighborAllToAllv size and offset maps should be integer vectors.");
    v_NeighborAlltoAllv(
        CommDataTypeTraits<T1>::GetPointer(pSendData),
        (int *)CommDataTypeTraits<T2>::GetPointer(pSendDataSizeMap),
        (int *)CommDataTypeTraits<T2>::GetPointer(pSendDataOffsetMap),
        CommDataTypeTraits<T1>::GetDataType(),
        CommDataTypeTraits<T1>::GetPointer(pRecvData),
        (int *)CommDataTypeTraits<T2>::GetPointer(pRecvDataSizeMap),
        (int *)CommDataTypeTraits<T2>::GetPointer(pRecvDataOffsetMap),
        CommDataTypeTraits<T1>::GetDataType());
}
 
/**
 * Starts a ready-mode nonblocking send
 *
 * @param pProc   Rank of destination
 * @param pData   Array/vector to send
 * @param count   Number of elements to send in pData
 * @param request Communication request object
 * @param loc     Location in request to use
 */
template <class T>
void Comm::Irsend(int pProc, T &pData, int count,
                  const CommRequestSharedPtr &request, int loc)
{
    v_Irsend(CommDataTypeTraits<T>::GetPointer(pData), count,
             CommDataTypeTraits<T>::GetDataType(), pProc, request, loc);
}
 
/**
 * Starts a nonblocking send
 *
 * @param pProc   Rank of destination
 * @param pData   Array/vector to send
 * @param count   Number of elements to send in pData
 * @param request Communication request object
 * @param loc     Location in request to use
 */
template <class T>
void Comm::Isend(int pProc, T &pData, int count,
                 const CommRequestSharedPtr &request, int loc)
{
    v_Isend(CommDataTypeTraits<T>::GetPointer(pData), count,
            CommDataTypeTraits<T>::GetDataType(), pProc, request, loc);
}
 
/**
 * Creates a persistent request for a send
 *
 * @param pProc   Rank of destination
 * @param pData   Array/vector to send
 * @param count   Number of elements to send in pData
 * @param request Communication request object
 * @param loc     Location in request to use
 */
template <class T>
void Comm::SendInit(int pProc, T &pData, int count,
                    const CommRequestSharedPtr &request, int loc)
{
    v_SendInit(CommDataTypeTraits<T>::GetPointer(pData), count,
               CommDataTypeTraits<T>::GetDataType(), pProc, request, loc);
}
 
/**
 * Begins a nonblocking receive
 *
 * @param pProc   Rank of source
 * @param pData   Array/vector to place incoming data in to
 * @param count   Number of elements to receive in to pData
 * @param request Communication request object
 * @param loc     Location in request to use
 */
template <class T>
void Comm::Irecv(int pProc, T &pData, int count,
                 const CommRequestSharedPtr &request, int loc)
{
    v_Irecv(CommDataTypeTraits<T>::GetPointer(pData), count,
            CommDataTypeTraits<T>::GetDataType(), pProc, request, loc);
}
 
/**
 * Create a persistent request for a receive
 *
 * @param pProc   Rank of source
 * @param pData   Array/vector to place incoming data in to
 * @param count   Number of elements to receive in to pData
 * @param request Communication request object
 * @param loc     Location in request to use
 */
template <class T>
void Comm::RecvInit(int pProc, T &pData, int count,
                    const CommRequestSharedPtr &request, int loc)
{
    v_RecvInit(CommDataTypeTraits<T>::GetPointer(pData), count,
               CommDataTypeTraits<T>::GetDataType(), pProc, request, loc);
}
 
/**
 * Starts a collection of persistent requests
 *
 * @param request Communication request object
 */
inline void Comm::StartAll(const CommRequestSharedPtr &request)
{
    v_StartAll(request);
}
 
/**
 * Waits for all CommRequests in the request object to complete.
 *
 * @param request Communication request object
 */
inline void Comm::WaitAll(const CommRequestSharedPtr &request)
{
    v_WaitAll(request);
}
 
/**
 * Creates a number of CommRequests.
 *
 * @param num Number of requests to generate in the communication request object
 *
 * @return Communication request object
 */
inline CommRequestSharedPtr Comm::CreateRequest(int num)
{
    return v_CreateRequest(num);
}
 
/**
 * @brief If the flag is non-zero create a new communicator.
 */
inline CommSharedPtr Comm::CommCreateIf(int flag)
{
    return v_CommCreateIf(flag);
}
 
/**
 * @brief Splits this communicator into a grid of size pRows*pColumns
 * and creates row and column communicators. By default the communicator
 * is a single row.
 */
inline void Comm::SplitComm(int pRows, int pColumns, int pTime)
{
    v_SplitComm(pRows, pColumns, pTime);
}
 
/**
 * @brief Retrieve the row communicator to which this process belongs.
 */
inline CommSharedPtr Comm::GetRowComm()
{
    if (!m_commRow.get())
    {
        return shared_from_this();
    }
    else
    {
        return m_commRow;
    }
}
 
/**
 * @brief Retrieve the column communicator to which this process
 * belongs.
 */
inline CommSharedPtr Comm::GetColumnComm()
{
    if (!m_commColumn.get())
    {
        return shared_from_this();
    }
    else
    {
        return m_commColumn;
    }
}
 
/**
 * @brief Retrieve the time communicator to which this process
 * belongs.
 */
inline CommSharedPtr Comm::GetTimeComm()
{
    if (!m_commTime.get())
    {
        return shared_from_this();
    }
    else
    {
        return m_commTime;
    }
}
 
/**
 * @brief Retrieve the space communicator to which this process
 * belongs.
 */
inline CommSharedPtr Comm::GetSpaceComm()
{
    if (!m_commSpace.get())
    {
        return shared_from_this();
    }
    else
    {
        return m_commSpace;
    }
}
 
/**
 *
 */
inline bool Comm::RemoveExistingFiles()
{
    return true;
}
 
/**
 *
 */
std::pair<CommSharedPtr, CommSharedPtr> Comm::SplitCommNode()
{
    return v_SplitCommNode();
}
 
} // namespace Nektar::LibUtilities
 
#endif