Communicator.hpp 6.78 KB
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#pragma once

#if HAVE_MPI
#include <array>
#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <string>
#include <type_traits>
#include <vector>

#include <mpi.h>

#include <dune/functions/common/functionconcepts.hh>

#include <amdis/common/parallel/Request.hpp>
#include <amdis/common/parallel/RecvDynamicSize.hpp>
#include <amdis/common/parallel/MpiTraits.hpp>

namespace AMDiS { namespace Mpi
{
  class Communicator
  {
  public:

    /// Constructor, stores an MPI communicator, e.g. MPI_COMM_WORLD
    Communicator(MPI_Comm comm)
      : comm_(comm)
      , buffer_(1024)
    {
      MPI_Comm_size(comm_, &size_);
      MPI_Comm_rank(comm_, &rank_);

      MPI_Buffer_attach(buffer_.data(), sizeof(char)*buffer_.size());
    }


  public:

    operator MPI_Comm() const { return comm_; }

    int size() const { return size_; }
    int rank() const { return rank_; }

  public:

    // send mpi datatype
    template <class Data>
    void send(Data const& data, int to, int tag = 0) const;

    // send array of mpi datatypes
    template <class T>
    void send(T const* data, std::size_t size, int to, int tag = 0) const;

    template <class T, std::size_t N>
    void send(T const (&data)[N], int to, int tag = 0) const
    {
      send(&data[0], N, to, tag);
    }

    template <class T, std::size_t N>
    void send(std::array<T,N> const& array, int to, int tag = 0) const
    {
      send(array.data(), N, to, tag);
    }

    template <class T>
    void send(std::vector<T> const& vec, int to, int tag = 0) const;

    void send(std::string const& str, int to, int tag = 0) const
    {
      MPI_Send(to_void_ptr(str.data()), int(str.size()), MPI_CHAR, to, tag, comm_);
    }


    // -------------------------------------------------------------------------------------


    // send mpi datatype (non-blocking)
    template <class Data>
    Request isend(Data const& data, int to, int tag = 0) const;

    // send mpi datatype (non-blocking, buffered)
    template <class Data>
    Request ibsend(Data const& data, int to, int tag = 0) const;

    // send array of mpi datatypes (non-blocking)
    template <class Data>
    Request isend(Data const* data, std::size_t size, int to, int tag = 0) const;

    // send array of mpi datatypes (non-blocking, buffered)
    template <class Data>
    Request ibsend(Data const* data, std::size_t size, int to, int tag = 0) const;

    template <class T>
    Request isend(std::vector<T> const& vec, int to, int tag = 0) const;

    Request isend(std::string const& str, int to, int tag = 0) const
    {
      MPI_Request request;
      MPI_Isend(to_void_ptr(str.data()), int(str.size()), MPI_CHAR, to, tag, comm_, &request);
      return {request};
    }

    // -------------------------------------------------------------------------------------

    // receive mpi datatype
    template <class Data>
    MPI_Status recv(Data& data, int from, int tag = 0) const;

    // receive array of mpi datatypes
    template <class T>
    MPI_Status recv(T* data, std::size_t size, int from, int tag = 0) const;

    template <class T, std::size_t N>
    MPI_Status recv(T (&data)[N], int from, int tag = 0) const
    {
      return recv(data, N, from, tag);
    }

    template <class T, std::size_t N>
    MPI_Status recv(std::array<T,N>& data, int from, int tag = 0) const
    {
      return recv(data.data(), N, from, tag);
    }

    template <class T>
    MPI_Status recv(std::vector<T>& data, int from, int tag = 0) const;

    MPI_Status recv(std::string& str, int from, int tag = 0) const
    {
      MPI_Status status;
      MPI_Probe(from, tag, comm_, &status);

      int size = 0;
      MPI_Get_count(&status, MPI_CHAR, &size);

      str.resize(size);
      MPI_Recv(&str[0], size, MPI_CHAR, from, tag, comm_, MPI_STATUS_IGNORE);
      return status;
    }

    // -------------------------------------------------------------------------------------

    // receive mpi datatype
    template <class Data>
    Request irecv(Data& data, int from, int tag = 0) const;

    // receive array of mpi datatypes
    template <class Data>
    Request irecv(Data* data, std::size_t size, int from, int tag = 0) const;

    template <class T, std::size_t N>
    Request irecv(T (&data)[N], int from, int tag = 0) const
    {
      return irecv(&data[0], N, from, tag);
    }

    template <class T, std::size_t N>
    Request irecv(std::array<T,N>& data, int from, int tag = 0) const
    {
      return irecv(data.data(), N, from, tag);
    }

    template <class Receiver>
      std::enable_if_t<Dune::Functions::Concept::isCallable<Receiver,MPI_Status>(), Request>
    irecv(Receiver&& recv, int from, int tag = 0) const
    {
      return Request{ RecvDynamicSize(from, tag, comm_, std::forward<Receiver>(recv)) };
    }

    // receive vector of mpi datatypes
    // 1. until message received, call MPI_Iprobe to retrieve status and size of message
    // 2. resize data-vector
    // 3. receive data into vector
    template <class T>
    Request irecv(std::vector<T>& vec, int from, int tag = 0) const;

    Request irecv(std::string& str, int from, int tag = 0) const
    {
      return Request{RecvDynamicSize(from,tag,comm_,
        [comm=comm_,&str](MPI_Status status) -> MPI_Request
        {
          int size = 0;
          MPI_Get_count(&status, MPI_CHAR, &size);

          str.resize(size);
          MPI_Request req;
          MPI_Irecv(&str[0], size, MPI_CHAR, status.MPI_SOURCE, status.MPI_TAG, comm, &req);

          return req;
        }) };
    }


  protected:

    // free unused buffers
    void check_buffers() const
    {
      using Buffers = std::decay_t<decltype(buffers_)>;

      std::list<typename Buffers::iterator> remove;
      for (auto it = buffers_.begin(); it != buffers_.end(); ++it) {
        int flag;
        MPI_Request_get_status(it->first, &flag, MPI_STATUS_IGNORE);
        if (flag != 0)
          remove.push_back(it);
      }

      for (auto it : remove)
        buffers_.erase(it);
    }


    std::pair<MPI_Request, std::string>& make_buffer(MPI_Status status, std::size_t len) const
    {
      auto it = buffers_.emplace(buffers_.end(), MPI_Request{}, std::string(len,' '));
      buffers_iterators_[{status.MPI_SOURCE, status.MPI_TAG}] = it;
      return buffers_.back();
    }

    std::pair<MPI_Request, std::string>& get_buffer(MPI_Status status) const
    {
      auto it = buffers_iterators_[{status.MPI_SOURCE, status.MPI_TAG}];
      return *it;
    }

  protected:

    MPI_Comm comm_;

    int rank_ = 0;
    int size_ = 1;

    std::vector<char> buffer_;

    using BufferList = std::list< std::pair<MPI_Request, std::string> >;
    mutable BufferList buffers_;

    using BufferIter = BufferList::iterator;
    mutable std::map<std::pair<int,int>, BufferIter> buffers_iterators_;
  };

}} // end namespace AMDiS::Mpi

#endif // HAVE_MPI

#include <amdis/common/parallel/Communicator.inc.hpp>