C++ communicator::size方法代码示例

void
all_to_all_test(const communicator& comm, Generator generator,
                const char* kind)
{
  typedef typename Generator::result_type value_type;

  using boost::mpi::all_to_all;

  std::vector<value_type> in_values;
  for (int p = 0; p < comm.size(); ++p)
    in_values.push_back(generator((p + 1) * (comm.rank() + 1)));

  if (comm.rank() == 0) {
    std::cout << "Performing all-to-all operation on " << kind << "...";
    std::cout.flush();
  }
  std::vector<value_type> out_values;
  all_to_all(comm, in_values, out_values);

  for (int p = 0; p < comm.size(); ++p) {
    BOOST_CHECK(out_values[p] == generator((p + 1) * (comm.rank() + 1)));
  }

  if (comm.rank() == 0) {
    std::cout << " done." << std::endl;
  }

  (comm.barrier)();
}

    static void gather(const communicator& comm, const std::vector<T>& in, std::vector< std::vector<T> >& out, int root)
    {
      std::vector<int>  counts(comm.size());
      Collectives<int,void*>::gather(comm, (int) in.size(), counts, root);

      std::vector<int>  offsets(comm.size(), 0);
      for (unsigned i = 1; i < offsets.size(); ++i)
        offsets[i] = offsets[i-1] + counts[i-1];

      std::vector<T> buffer(offsets.back() + counts.back());
      MPI_Gatherv(Datatype::address(const_cast<T&>(in[0])),
                  in.size(),
                  Datatype::datatype(),
                  Datatype::address(buffer[0]),
                  &counts[0],
                  &offsets[0],
                  Datatype::datatype(),
                  root, comm);

      out.resize(comm.size());
      size_t cur = 0;
      for (unsigned i = 0; i < (unsigned)comm.size(); ++i)
      {
          out[i].reserve(counts[i]);
          for (unsigned j = 0; j < (unsigned)counts[i]; ++j)
              out[i].push_back(buffer[cur++]);
      }
    }

void
gather_test(const communicator& comm, Generator generator,
            const char* kind, int root = -1)
{
  typedef typename Generator::result_type value_type;
  value_type value = generator(comm.rank());

  if (root == -1) {
    for (root = 0; root < comm.size(); ++root)
      gather_test(comm, generator, kind, root);
  } else {
    using boost::mpi::gather;

    std::vector<value_type> values;
    if (comm.rank() == root) {
      std::cout << "Gathering " << kind << " from root "
                << root << "..." << std::endl;
    }

    gather(comm, value, values, root);

    if (comm.rank() == root) {
      std::vector<value_type> expected_values;
      for (int p = 0; p < comm.size(); ++p)
        expected_values.push_back(generator(p));
      BOOST_CHECK(values == expected_values);
    } else {
      BOOST_CHECK(values.empty());
    }
  }

  (comm.barrier)();
}

void
scatter_test(const communicator& comm, Generator generator,
            const char* kind, int root = -1)
{
  typedef typename Generator::result_type value_type;

  if (root == -1) {
    for (root = 0; root < comm.size(); ++root)
      scatter_test(comm, generator, kind, root);
  } else {
    using boost::mpi::scatter;

    value_type value;

    if (comm.rank() == root) {
      std::vector<value_type> values;

      for (int p = 0; p < comm.size(); ++p)
        values.push_back(generator(p));

      if (comm.rank() == root) {
        std::cout << "Scattering " << kind << " from root " << root << "...";
        std::cout.flush();
      }

      scatter(comm, values, value, root);
    } else {
      scatter(comm, value, root);
    }

    BOOST_CHECK(value == generator(comm.rank()));
  }

  (comm.barrier)();
}

object all_to_all(const communicator& comm, object in_values)
{
  // Build input values
  std::vector<object> in_values_vec(comm.size());
  object iterator = object(handle<>(PyObject_GetIter(in_values.ptr())));
  for (int i = 0; i < comm.size(); ++i)
    in_values_vec[i] = object(handle<>(PyIter_Next(iterator.ptr())));

  std::vector<object> out_values_vec(comm.size());
  boost::mpi::all_to_all(comm, in_values_vec, out_values_vec);

  boost::python::list l;
  for (int i = 0; i < comm.size(); ++i)
    l.append(out_values_vec[i]);
  return boost::python::tuple(l);
}

object scatter(const communicator& comm, object values, int root)
{
  object result;

  if (comm.rank() == root) {
    std::vector<object> values_vec(comm.size());
    object iterator = object(handle<>(PyObject_GetIter(values.ptr())));
    for (int i = 0; i < comm.size(); ++i)
      values_vec[i] = object(handle<>(PyIter_Next(iterator.ptr())));

    boost::mpi::scatter(comm, values_vec, result, root);
  } else {
    boost::mpi::scatter(comm, result, root);
  }
  return result;
}

void
broadcast_test(const communicator& comm, const T& bc_value,
               const char* kind, int root = -1)
{
  if (root == -1) {
    for (root = 0; root < comm.size(); ++root)
      broadcast_test(comm, bc_value, kind, root);
  } else {
    using boost::mpi::broadcast;

    T value;
    if (comm.rank() == root) {
      value = bc_value;
      std::cout << "Broadcasting " << kind << " from root " << root << "...";
      std::cout.flush();
    }

    broadcast(comm, value, root);
    BOOST_CHECK(value == bc_value);
    if (comm.rank() == root && value == bc_value)
      std::cout << "OK." << std::endl;
  }

  (comm.barrier)();
}

void
ring_array_test(const communicator& comm, const T* pass_values,
                int n, const char* kind, int root = 0)
{
  T* transferred_values = new T[n];
  int rank = comm.rank();
  int size = comm.size();

  if (rank == root) {

    std::cout << "Passing " << kind << " array around a ring from root "
              << root  << "...";
    comm.send((rank + 1) % size, 0, pass_values, n);
    comm.recv((rank + size - 1) % size, 0, transferred_values, n);
    bool okay = std::equal(pass_values, pass_values + n,
                           transferred_values);
    BOOST_CHECK(okay);
    if (okay) std::cout << " OK." << std::endl;
  } else {
    status stat = comm.probe(boost::mpi::any_source, 0);
    boost::optional<int> num_values = stat.template count<T>();
    if (boost::mpi::is_mpi_datatype<T>())
      BOOST_CHECK(num_values && *num_values == n);
    else
      BOOST_CHECK(!num_values || *num_values == n);     
    comm.recv(stat.source(), 0, transferred_values, n);
    BOOST_CHECK(std::equal(pass_values, pass_values + n,
                           transferred_values));
    comm.send((rank + 1) % size, 0, transferred_values, n);
  }
  (comm.barrier)();
  delete [] transferred_values;
}

 template <typename T> std::vector<T> mpi_scatter(std::vector<T> const &a, communicator c, int root, std::true_type) {
  auto slow_size = a.size();
  auto sendcounts = std::vector<int>(c.size());
  auto displs = std::vector<int>(c.size() + 1, 0);
  int recvcount = slice_length(slow_size - 1, c.size(), c.rank());
  std::vector<T> b(recvcount);

  for (int r = 0; r < c.size(); ++r) {
   sendcounts[r] = slice_length(slow_size - 1, c.size(), r);
   displs[r + 1] = sendcounts[r] + displs[r];
  }

  MPI_Scatterv((void *)a.data(), &sendcounts[0], &displs[0], mpi_datatype<T>(), (void *)b.data(), recvcount, mpi_datatype<T>(),
               root, c.get());
  return b;
 }

 void all_gather(const communicator& comm, const T& in_val, std::vector<T>& out_vals) {
     out_vals.resize(comm.size());
     MPI_Allgather((void*)&in_val, 1, detail::mpi_type<T>(),
                   &out_vals.front(), 1, detail::mpi_type<T>(),
                   comm);
     // throw std::logic_error(std::string("all_gather() is not implemented, called for type T=")
     //                        +typeid(T).name());
 }

object all_gather(const communicator& comm, object value)
{
  std::vector<object> values;
  boost::mpi::all_gather(comm, value, values);

  boost::python::list l;
  for (int i = 0; i < comm.size(); ++i)
    l.append(values[i]);
  return boost::python::tuple(l);
}

void
gatherv_test(const communicator& comm, Generator generator,
             const char* kind, int root = -1)
{
  typedef typename Generator::result_type value_type;

  if (root == -1) {
    for (root = 0; root < comm.size(); ++root)
      gatherv_test(comm, generator, kind, root);
  } else {
    using boost::mpi::gatherv;

    int mysize = comm.rank() + 1;
    int nprocs = comm.size();

    // process p will send p+1 identical generator(p) elements
    std::vector<value_type> myvalues(mysize, generator(comm.rank()));

    if (comm.rank() == root) {
      std::vector<value_type> values((nprocs*(nprocs+1))/2);
      std::vector<int> sizes(comm.size());
      for (int p = 0; p < comm.size(); ++p)
        sizes[p] = p + 1;

      std::cout << "Gatheringv " << kind << " from root "
                << root << "..." << std::endl;

      gatherv(comm, myvalues, &values[0], sizes, root);

      std::vector<value_type> expected_values;
      for (int p = 0; p < comm.size(); ++p)
        for (int i = 0; i < p+1; ++i)
          expected_values.push_back(generator(p));

      BOOST_CHECK(values == expected_values);
    } else {
      gatherv(comm, myvalues, root);
    }
  }

  (comm.barrier)();
}

void
gather(const communicator& comm, const T* in_values, int n, 
       std::vector<T>& out_values, int root)
{
  if (comm.rank() == root) {
    out_values.resize(comm.size() * n);
    ::boost::mpi::gather(comm, in_values, n, &out_values[0], root);
  } 
  else
    ::boost::mpi::gather(comm, in_values, n, root);
}

object gather(const communicator& comm, object value, int root)
{
  if (comm.rank() == root) {
    std::vector<object> values;
    boost::mpi::gather(comm, value, values, root);

    boost::python::list l;
    for (int i = 0; i < comm.size(); ++i)
      l.append(values[i]);
    return boost::python::tuple(l);
  } else {
    boost::mpi::gather(comm, value, root);
    return object();
  }
}

void
all_gather_impl(const communicator& comm, const T* in_values, int n, 
                T* out_values, int const* sizes, int const* skips, mpl::false_)
{
  int nproc = comm.size();
  // first, gather all size, these size can be different for
  // each process
  packed_oarchive oa(comm);
  for (int i = 0; i < n; ++i) {
    oa << in_values[i];
  }
  std::vector<int> oasizes(nproc);
  int oasize = oa.size();
  BOOST_MPI_CHECK_RESULT(MPI_Allgather,
                         (&oasize, 1, MPI_INTEGER,
                          c_data(oasizes), 1, MPI_INTEGER, 
                          MPI_Comm(comm)));
  // Gather the archives, which can be of different sizes, so
  // we need to use allgatherv.
  // Every thing is contiguous, so the offsets can be
  // deduced from the collected sizes.
  std::vector<int> offsets(nproc);
  sizes2offsets(oasizes, offsets);
  packed_iarchive::buffer_type recv_buffer(std::accumulate(oasizes.begin(), oasizes.end(), 0));
  BOOST_MPI_CHECK_RESULT(MPI_Allgatherv,
                         (const_cast<void*>(oa.address()), int(oa.size()), MPI_BYTE,
                          c_data(recv_buffer), c_data(oasizes), c_data(offsets), MPI_BYTE, 
                          MPI_Comm(comm)));
  for (int src = 0; src < nproc; ++src) {
    int nb   = sizes ? sizes[src] : n;
    int skip = skips ? skips[src] : 0;
    std::advance(out_values, skip);
    if (src == comm.rank()) { // this is our local data
      for (int i = 0; i < nb; ++i) {
        *out_values++ = *in_values++;
      }
    } else {
      packed_iarchive ia(comm,  recv_buffer, boost::archive::no_header, offsets[src]);
      for (int i = 0; i < nb; ++i) {
        ia >> *out_values++;
      }
    }
  }
}