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 <vector>
  12
  13 #include <boost/mpi/exception.hpp>
  14 #include <boost/mpi/datatype.hpp>
  15 #include <boost/mpi/packed_oarchive.hpp>
  16 #include <boost/mpi/packed_iarchive.hpp>
  17 #include <boost/mpi/detail/point_to_point.hpp>
  18 #include <boost/mpi/communicator.hpp>
  19 #include <boost/mpi/environment.hpp>
  20 #include <boost/mpi/detail/offsets.hpp>
  21 #include <boost/assert.hpp>
  22 #include <boost/scoped_array.hpp>
  23
  24 namespace boost { namespace mpi {
  25
  26 namespace detail {
  27   // We're gathering at the root for a type that has an associated MPI
  28   // datatype, so we'll use MPI_Gatherv to do all of the work.
  29   template<typename T>
  30   void
  31   gatherv_impl(const communicator& comm, const T* in_values, int in_size,
  32                T* out_values, const int* sizes, const int* displs, int root, mpl::true_)
  33   {
  34     MPI_Datatype type = get_mpi_datatype<T>(*in_values);
  35     BOOST_MPI_CHECK_RESULT(MPI_Gatherv,
  36                            (const_cast<T*>(in_values), in_size, type,
  37                             out_values, const_cast<int*>(sizes), const_cast<int*>(displs),
  38                             type, root, comm));
  39   }
  40
  41   // We're gathering from a non-root for a type that has an associated MPI
  42   // datatype, so we'll use MPI_Gatherv to do all of the work.
  43   template<typename T>
  44   void
  45   gatherv_impl(const communicator& comm, const T* in_values, int in_size, int root,
  46               mpl::true_)
  47   {
  48     MPI_Datatype type = get_mpi_datatype<T>(*in_values);
  49     BOOST_MPI_CHECK_RESULT(MPI_Gatherv,
  50                            (const_cast<T*>(in_values), in_size, type,
  51                             0, 0, 0, type, root, comm));
  52   }
  53
  54   // We're gathering at the root for a type that does not have an
  55   // associated MPI datatype, so we'll need to serialize
  56   // it. Unfortunately, this means that we cannot use MPI_Gatherv, so
  57   // we'll just have all of the non-root nodes send individual
  58   // messages to the root.
  59   template<typename T>
  60   void
  61   gatherv_impl(const communicator& comm, const T* in_values, int in_size,
  62                T* out_values, const int* sizes, const int* displs, int root, mpl::false_)
  63   {
  64     // convert displacement to offsets to skip
  65     scoped_array<int> skipped(make_skipped_slots(comm, sizes, displs, root));
  66     gather_impl(comm, in_values, in_size, out_values, sizes, skipped.get(), root, mpl::false_());
  67   }
  68
  69   // We're gathering at a non-root for a type that does not have an
  70   // associated MPI datatype, so we'll need to serialize
  71   // it.
  72   template<typename T>
  73   void
  74   gatherv_impl(const communicator& comm, const T* in_values, int in_size, int root,
  75               mpl::false_)
  76   {
  77     gather_impl(comm, in_values, in_size, (T*)0,(int const*)0,(int const*)0, root,
  78                 mpl::false_());
  79   }
  80 } // end namespace detail
  81
  82 template<typename T>
  83 void
  84 gatherv(const communicator& comm, const T* in_values, int in_size,
  85         T* out_values, const std::vector<int>& sizes, const std::vector<int>& displs,
  86         int root)
  87 {
  88   if (comm.rank() == root)
  89     detail::gatherv_impl(comm, in_values, in_size,
  90                          out_values, &sizes[0], &displs[0],
  91                          root, is_mpi_datatype<T>());
  92   else
  93     detail::gatherv_impl(comm, in_values, in_size, root, is_mpi_datatype<T>());
  94 }
  95
  96 template<typename T>
  97 void
  98 gatherv(const communicator& comm, const std::vector<T>& in_values,
  99         T* out_values, const std::vector<int>& sizes, const std::vector<int>& displs,
 100         int root)
 101 {
 102   ::boost::mpi::gatherv(comm, &in_values[0], in_values.size(), out_values, sizes, displs, root);
 103 }
 104
 105 template<typename T>
 106 void gatherv(const communicator& comm, const T* in_values, int in_size, int root)
 107 {
 108   BOOST_ASSERT(comm.rank() != root);
 109   detail::gatherv_impl(comm, in_values, in_size, root, is_mpi_datatype<T>());
 110 }
 111
 112 template<typename T>
 113 void gatherv(const communicator& comm, const std::vector<T>& in_values, int root)
 114 {
 115   BOOST_ASSERT(comm.rank() != root);
 116   detail::gatherv_impl(comm, &in_values[0], in_values.size(), root, is_mpi_datatype<T>());
 117 }
 118
 119 ///////////////////////
 120 // common use versions
 121 ///////////////////////
 122 template<typename T>
 123 void
 124 gatherv(const communicator& comm, const T* in_values, int in_size,
 125         T* out_values, const std::vector<int>& sizes, int root)
 126 {
 127   int nprocs = comm.size();
 128
 129   std::vector<int> displs( nprocs );
 130   for (int rank = 0, aux = 0; rank < nprocs; ++rank) {
 131     displs[rank] = aux;
 132     aux += sizes[rank];
 133   }
 134   ::boost::mpi::gatherv(comm, in_values, in_size, out_values, sizes, displs, root);
 135 }
 136
 137 template<typename T>
 138 void
 139 gatherv(const communicator& comm, const std::vector<T>& in_values,
 140         T* out_values, const std::vector<int>& sizes, int root)
 141 {
 142   ::boost::mpi::gatherv(comm, &in_values[0], in_values.size(), out_values, sizes, root);
 143 }
 144
 145 } } // end namespace boost::mpi
 146
 147 #endif // BOOST_MPI_GATHERV_HPP