ceph/src/boost/boost/mpi/collectives/gatherv.hpp

   1 // Copyright (C) 2011 Júlio Hoffimann.
   2
   3 // Use, modification and distribution is subject to the Boost Software
   4 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6
   7 // Message Passing Interface 1.1 -- Section 4.5. Gatherv
   8 #ifndef BOOST_MPI_GATHERV_HPP
   9 #define BOOST_MPI_GATHERV_HPP
  10
  11 #include <boost/mpi/exception.hpp>
  12 #include <boost/mpi/datatype.hpp>
  13 #include <vector>
  14 #include <boost/mpi/packed_oarchive.hpp>
  15 #include <boost/mpi/packed_iarchive.hpp>
  16 #include <boost/mpi/detail/point_to_point.hpp>
  17 #include <boost/mpi/communicator.hpp>
  18 #include <boost/mpi/environment.hpp>
  19 #include <boost/assert.hpp>
  20
  21 namespace boost { namespace mpi {
  22
  23 namespace detail {
  24   // We're gathering at the root for a type that has an associated MPI
  25   // datatype, so we'll use MPI_Gatherv to do all of the work.
  26   template<typename T>
  27   void
  28   gatherv_impl(const communicator& comm, const T* in_values, int in_size,
  29                T* out_values, const int* sizes, const int* displs, int root, mpl::true_)
  30   {
  31     MPI_Datatype type = get_mpi_datatype<T>(*in_values);
  32     BOOST_MPI_CHECK_RESULT(MPI_Gatherv,
  33                            (const_cast<T*>(in_values), in_size, type,
  34                             out_values, const_cast<int*>(sizes), const_cast<int*>(displs),
  35                             type, root, comm));
  36   }
  37
  38   // We're gathering from a non-root for a type that has an associated MPI
  39   // datatype, so we'll use MPI_Gatherv to do all of the work.
  40   template<typename T>
  41   void
  42   gatherv_impl(const communicator& comm, const T* in_values, int in_size, int root,
  43               mpl::true_)
  44   {
  45     MPI_Datatype type = get_mpi_datatype<T>(*in_values);
  46     BOOST_MPI_CHECK_RESULT(MPI_Gatherv,
  47                            (const_cast<T*>(in_values), in_size, type,
  48                             0, 0, 0, type, root, comm));
  49   }
  50
  51   // We're gathering at the root for a type that does not have an
  52   // associated MPI datatype, so we'll need to serialize
  53   // it. Unfortunately, this means that we cannot use MPI_Gatherv, so
  54   // we'll just have all of the non-root nodes send individual
  55   // messages to the root.
  56   template<typename T>
  57   void
  58   gatherv_impl(const communicator& comm, const T* in_values, int in_size,
  59                T* out_values, const int* sizes, const int* displs, int root, mpl::false_)
  60   {
  61     int tag = environment::collectives_tag();
  62     int nprocs = comm.size();
  63
  64     for (int src = 0; src < nprocs; ++src) {
  65       if (src == root)
  66         // Our own values will never be transmitted: just copy them.
  67         std::copy(in_values, in_values + in_size, out_values + displs[src]);
  68       else {
  69 //        comm.recv(src, tag, out_values + displs[src], sizes[src]);
  70         // Receive archive
  71         packed_iarchive ia(comm);
  72         MPI_Status status;
  73         detail::packed_archive_recv(comm, src, tag, ia, status);
  74         for (int i = 0; i < sizes[src]; ++i)
  75           ia >> out_values[ displs[src] + i ];
  76       }
  77     }
  78   }
  79
  80   // We're gathering at a non-root for a type that does not have an
  81   // associated MPI datatype, so we'll need to serialize
  82   // it. Unfortunately, this means that we cannot use MPI_Gatherv, so
  83   // we'll just have all of the non-root nodes send individual
  84   // messages to the root.
  85   template<typename T>
  86   void
  87   gatherv_impl(const communicator& comm, const T* in_values, int in_size, int root,
  88               mpl::false_)
  89   {
  90     int tag = environment::collectives_tag();
  91 //    comm.send(root, tag, in_values, in_size);
  92     packed_oarchive oa(comm);
  93     for (int i = 0; i < in_size; ++i)
  94       oa << in_values[i];
  95     detail::packed_archive_send(comm, root, tag, oa);
  96   }
  97 } // end namespace detail
  98
  99 template<typename T>
 100 void
 101 gatherv(const communicator& comm, const T* in_values, int in_size,
 102         T* out_values, const std::vector<int>& sizes, const std::vector<int>& displs,
 103         int root)
 104 {
 105   if (comm.rank() == root)
 106     detail::gatherv_impl(comm, in_values, in_size,
 107                          out_values, &sizes[0], &displs[0],
 108                          root, is_mpi_datatype<T>());
 109   else
 110     detail::gatherv_impl(comm, in_values, in_size, root, is_mpi_datatype<T>());
 111 }
 112
 113 template<typename T>
 114 void
 115 gatherv(const communicator& comm, const std::vector<T>& in_values,
 116         T* out_values, const std::vector<int>& sizes, const std::vector<int>& displs,
 117         int root)
 118 {
 119   ::boost::mpi::gatherv(comm, &in_values[0], in_values.size(), out_values, sizes, displs, root);
 120 }
 121
 122 template<typename T>
 123 void gatherv(const communicator& comm, const T* in_values, int in_size, int root)
 124 {
 125   BOOST_ASSERT(comm.rank() != root);
 126   detail::gatherv_impl(comm, in_values, in_size, root, is_mpi_datatype<T>());
 127 }
 128
 129 template<typename T>
 130 void gatherv(const communicator& comm, const std::vector<T>& in_values, int root)
 131 {
 132   BOOST_ASSERT(comm.rank() != root);
 133   detail::gatherv_impl(comm, &in_values[0], in_values.size(), root, is_mpi_datatype<T>());
 134 }
 135
 136 ///////////////////////
 137 // common use versions
 138 ///////////////////////
 139 template<typename T>
 140 void
 141 gatherv(const communicator& comm, const T* in_values, int in_size,
 142         T* out_values, const std::vector<int>& sizes, int root)
 143 {
 144   int nprocs = comm.size();
 145
 146   std::vector<int> displs( nprocs );
 147   for (int rank = 0, aux = 0; rank < nprocs; ++rank) {
 148     displs[rank] = aux;
 149     aux += sizes[rank];
 150   }
 151   ::boost::mpi::gatherv(comm, in_values, in_size, out_values, sizes, displs, root);
 152 }
 153
 154 template<typename T>
 155 void
 156 gatherv(const communicator& comm, const std::vector<T>& in_values,
 157         T* out_values, const std::vector<int>& sizes, int root)
 158 {
 159   ::boost::mpi::gatherv(comm, &in_values[0], in_values.size(), out_values, sizes, root);
 160 }
 161
 162 } } // end namespace boost::mpi
 163
 164 #endif // BOOST_MPI_GATHERV_HPP