// Copyright (C) 2005-2006 Douglas Gregor <doug.gregor -at- gmail.com>. // Use, modification and distribution is subject to the Boost Software // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // Message Passing Interface 1.1 -- Section 4.7. Gather-to-all #ifndef BOOST_MPI_ALL_GATHER_HPP #define BOOST_MPI_ALL_GATHER_HPP #include <boost/mpi/exception.hpp> #include <boost/mpi/datatype.hpp> #include <vector> #include <boost/serialization/vector.hpp> // all_gather falls back to gather+broadcast in some cases #include <boost/mpi/collectives/broadcast.hpp> #include <boost/mpi/collectives/gather.hpp> namespace boost { namespace mpi { namespace detail { // We're all-gathering for a type that has an associated MPI // datatype, so we'll use MPI_Gather to do all of the work. template<typename T> void all_gather_impl(const communicator& comm, const T* in_values, int n, T* out_values, mpl::true_) { MPI_Datatype type = boost::mpi::get_mpi_datatype<T>(*in_values); BOOST_MPI_CHECK_RESULT(MPI_Allgather, (const_cast<T*>(in_values), n, type, out_values, n, type, comm)); } // We're all-gathering for a type that has no associated MPI // type. So, we'll do a manual gather followed by a broadcast. template<typename T> void all_gather_impl(const communicator& comm, const T* in_values, int n, T* out_values, mpl::false_) { gather(comm, in_values, n, out_values, 0); broadcast(comm, out_values, comm.size() * n, 0); } } // end namespace detail template<typename T> inline void all_gather(const communicator& comm, const T& in_value, T* out_values) { detail::all_gather_impl(comm, &in_value, 1, out_values, is_mpi_datatype<T>()); } template<typename T> void all_gather(const communicator& comm, const T& in_value, std::vector<T>& out_values) { out_values.resize(comm.size()); ::boost::mpi::all_gather(comm, &in_value, 1, &out_values[0]); } template<typename T> inline void all_gather(const communicator& comm, const T* in_values, int n, T* out_values) { detail::all_gather_impl(comm, in_values, n, out_values, is_mpi_datatype<T>()); } template<typename T> void all_gather(const communicator& comm, const T* in_values, int n, std::vector<T>& out_values) { out_values.resize(comm.size() * n); ::boost::mpi::all_gather(comm, in_values, n, &out_values[0]); } } } // end namespace boost::mpi #endif // BOOST_MPI_ALL_GATHER_HPP