83 lines
2.6 KiB
C++
83 lines
2.6 KiB
C++
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// Copyright (C) 2005-2006 Douglas Gregor <doug.gregor -at- gmail.com>.
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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 4.7. Gather-to-all
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#ifndef BOOST_MPI_ALL_GATHER_HPP
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#define BOOST_MPI_ALL_GATHER_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/serialization/vector.hpp>
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// all_gather falls back to gather+broadcast in some cases
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#include <boost/mpi/collectives/broadcast.hpp>
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#include <boost/mpi/collectives/gather.hpp>
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namespace boost { namespace mpi {
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namespace detail {
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// We're all-gathering for a type that has an associated MPI
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// datatype, so we'll use MPI_Gather to do all of the work.
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template<typename T>
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void
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all_gather_impl(const communicator& comm, const T* in_values, int n,
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T* out_values, mpl::true_)
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{
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MPI_Datatype type = boost::mpi::get_mpi_datatype<T>(*in_values);
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BOOST_MPI_CHECK_RESULT(MPI_Allgather,
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(const_cast<T*>(in_values), n, type,
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out_values, n, type, comm));
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}
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// We're all-gathering for a type that has no associated MPI
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// type. So, we'll do a manual gather followed by a broadcast.
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template<typename T>
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void
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all_gather_impl(const communicator& comm, const T* in_values, int n,
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T* out_values, mpl::false_)
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{
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gather(comm, in_values, n, out_values, 0);
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broadcast(comm, out_values, comm.size() * n, 0);
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}
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} // end namespace detail
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template<typename T>
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inline void
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all_gather(const communicator& comm, const T& in_value, T* out_values)
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{
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detail::all_gather_impl(comm, &in_value, 1, out_values, is_mpi_datatype<T>());
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}
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template<typename T>
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void
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all_gather(const communicator& comm, const T& in_value,
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std::vector<T>& out_values)
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{
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out_values.resize(comm.size());
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::boost::mpi::all_gather(comm, &in_value, 1, &out_values[0]);
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}
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template<typename T>
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inline void
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all_gather(const communicator& comm, const T* in_values, int n, T* out_values)
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{
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detail::all_gather_impl(comm, in_values, n, out_values, is_mpi_datatype<T>());
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}
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template<typename T>
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void
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all_gather(const communicator& comm, const T* in_values, int n,
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std::vector<T>& out_values)
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{
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out_values.resize(comm.size() * n);
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::boost::mpi::all_gather(comm, in_values, n, &out_values[0]);
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}
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} } // end namespace boost::mpi
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#endif // BOOST_MPI_ALL_GATHER_HPP
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