165 lines
5.8 KiB
C++
165 lines
5.8 KiB
C++
// Copyright (C) 2011 Júlio Hoffimann.
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// Use, modification and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Message Passing Interface 1.1 -- Section 4.5. Gatherv
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#ifndef BOOST_MPI_GATHERV_HPP
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#define BOOST_MPI_GATHERV_HPP
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#include <boost/mpi/exception.hpp>
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#include <boost/mpi/datatype.hpp>
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#include <vector>
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#include <boost/mpi/packed_oarchive.hpp>
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#include <boost/mpi/packed_iarchive.hpp>
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#include <boost/mpi/detail/point_to_point.hpp>
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#include <boost/mpi/communicator.hpp>
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#include <boost/mpi/environment.hpp>
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#include <boost/assert.hpp>
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namespace boost { namespace mpi {
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namespace detail {
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// We're gathering at the root for a type that has an associated MPI
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// datatype, so we'll use MPI_Gatherv to do all of the work.
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template<typename T>
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void
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gatherv_impl(const communicator& comm, const T* in_values, int in_size,
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T* out_values, const int* sizes, const int* displs, int root, mpl::true_)
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{
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MPI_Datatype type = get_mpi_datatype<T>(*in_values);
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BOOST_MPI_CHECK_RESULT(MPI_Gatherv,
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(const_cast<T*>(in_values), in_size, type,
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out_values, const_cast<int*>(sizes), const_cast<int*>(displs),
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type, root, comm));
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}
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// We're gathering from a non-root for a type that has an associated MPI
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// datatype, so we'll use MPI_Gatherv to do all of the work.
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template<typename T>
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void
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gatherv_impl(const communicator& comm, const T* in_values, int in_size, int root,
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mpl::true_)
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{
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MPI_Datatype type = get_mpi_datatype<T>(*in_values);
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BOOST_MPI_CHECK_RESULT(MPI_Gatherv,
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(const_cast<T*>(in_values), in_size, type,
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0, 0, 0, type, root, comm));
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}
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// We're gathering at the root for a type that does not have an
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// associated MPI datatype, so we'll need to serialize
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// it. Unfortunately, this means that we cannot use MPI_Gatherv, so
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// we'll just have all of the non-root nodes send individual
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// messages to the root.
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template<typename T>
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void
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gatherv_impl(const communicator& comm, const T* in_values, int in_size,
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T* out_values, const int* sizes, const int* displs, int root, mpl::false_)
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{
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int tag = environment::collectives_tag();
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int nprocs = comm.size();
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for (int src = 0; src < nprocs; ++src) {
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if (src == root)
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// Our own values will never be transmitted: just copy them.
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std::copy(in_values, in_values + in_size, out_values + displs[src]);
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else {
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// comm.recv(src, tag, out_values + displs[src], sizes[src]);
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// Receive archive
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packed_iarchive ia(comm);
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MPI_Status status;
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detail::packed_archive_recv(comm, src, tag, ia, status);
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for (int i = 0; i < sizes[src]; ++i)
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ia >> out_values[ displs[src] + i ];
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}
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}
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}
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// We're gathering at a non-root for a type that does not have an
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// associated MPI datatype, so we'll need to serialize
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// it. Unfortunately, this means that we cannot use MPI_Gatherv, so
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// we'll just have all of the non-root nodes send individual
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// messages to the root.
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template<typename T>
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void
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gatherv_impl(const communicator& comm, const T* in_values, int in_size, int root,
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mpl::false_)
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{
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int tag = environment::collectives_tag();
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// comm.send(root, tag, in_values, in_size);
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packed_oarchive oa(comm);
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for (int i = 0; i < in_size; ++i)
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oa << in_values[i];
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detail::packed_archive_send(comm, root, tag, oa);
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}
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} // end namespace detail
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template<typename T>
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void
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gatherv(const communicator& comm, const T* in_values, int in_size,
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T* out_values, const std::vector<int>& sizes, const std::vector<int>& displs,
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int root)
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{
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if (comm.rank() == root)
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detail::gatherv_impl(comm, in_values, in_size,
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out_values, &sizes[0], &displs[0],
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root, is_mpi_datatype<T>());
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else
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detail::gatherv_impl(comm, in_values, in_size, root, is_mpi_datatype<T>());
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}
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template<typename T>
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void
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gatherv(const communicator& comm, const std::vector<T>& in_values,
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T* out_values, const std::vector<int>& sizes, const std::vector<int>& displs,
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int root)
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{
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::boost::mpi::gatherv(comm, &in_values[0], in_values.size(), out_values, sizes, displs, root);
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}
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template<typename T>
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void gatherv(const communicator& comm, const T* in_values, int in_size, int root)
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{
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BOOST_ASSERT(comm.rank() != root);
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detail::gatherv_impl(comm, in_values, in_size, root, is_mpi_datatype<T>());
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}
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template<typename T>
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void gatherv(const communicator& comm, const std::vector<T>& in_values, int root)
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{
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BOOST_ASSERT(comm.rank() != root);
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detail::gatherv_impl(comm, &in_values[0], in_values.size(), root, is_mpi_datatype<T>());
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}
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///////////////////////
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// common use versions
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///////////////////////
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template<typename T>
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void
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gatherv(const communicator& comm, const T* in_values, int in_size,
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T* out_values, const std::vector<int>& sizes, int root)
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{
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int nprocs = comm.size();
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std::vector<int> displs( nprocs );
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for (int rank = 0, aux = 0; rank < nprocs; ++rank) {
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displs[rank] = aux;
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aux += sizes[rank];
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}
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::boost::mpi::gatherv(comm, in_values, in_size, out_values, sizes, displs, root);
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}
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template<typename T>
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void
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gatherv(const communicator& comm, const std::vector<T>& in_values,
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T* out_values, const std::vector<int>& sizes, int root)
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{
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::boost::mpi::gatherv(comm, &in_values[0], in_values.size(), out_values, sizes, root);
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}
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} } // end namespace boost::mpi
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#endif // BOOST_MPI_GATHERV_HPP
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