Chris@16: // Copyright (C) 2005-2006 Douglas Gregor <doug.gregor -at- gmail.com>.
Chris@16: 
Chris@16: // Use, modification and distribution is subject to the Boost Software
Chris@16: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: // Message Passing Interface 1.1 -- Section 4.7. Gather-to-all
Chris@16: #ifndef BOOST_MPI_ALL_GATHER_HPP
Chris@16: #define BOOST_MPI_ALL_GATHER_HPP
Chris@16: 
Chris@16: #include <boost/mpi/exception.hpp>
Chris@16: #include <boost/mpi/datatype.hpp>
Chris@16: #include <vector>
Chris@16: #include <boost/serialization/vector.hpp>
Chris@16: 
Chris@16: // all_gather falls back to gather+broadcast in some cases
Chris@16: #include <boost/mpi/collectives/broadcast.hpp>
Chris@16: #include <boost/mpi/collectives/gather.hpp>
Chris@16: 
Chris@16: namespace boost { namespace mpi {
Chris@16: 
Chris@16: namespace detail {
Chris@16:   // We're all-gathering for a type that has an associated MPI
Chris@16:   // datatype, so we'll use MPI_Gather to do all of the work.
Chris@16:   template<typename T>
Chris@16:   void
Chris@16:   all_gather_impl(const communicator& comm, const T* in_values, int n, 
Chris@16:                   T* out_values, mpl::true_)
Chris@16:   {
Chris@16:     MPI_Datatype type = boost::mpi::get_mpi_datatype<T>(*in_values);
Chris@16:     BOOST_MPI_CHECK_RESULT(MPI_Allgather,
Chris@16:                            (const_cast<T*>(in_values), n, type,
Chris@16:                             out_values, n, type, comm));
Chris@16:   }
Chris@16: 
Chris@16:   // We're all-gathering for a type that has no associated MPI
Chris@16:   // type. So, we'll do a manual gather followed by a broadcast.
Chris@16:   template<typename T>
Chris@16:   void
Chris@16:   all_gather_impl(const communicator& comm, const T* in_values, int n, 
Chris@16:                   T* out_values, mpl::false_)
Chris@16:   {
Chris@16:     gather(comm, in_values, n, out_values, 0);
Chris@16:     broadcast(comm, out_values, comm.size() * n, 0);
Chris@16:   }
Chris@16: } // end namespace detail
Chris@16: 
Chris@16: template<typename T>
Chris@16: inline void
Chris@16: all_gather(const communicator& comm, const T& in_value, T* out_values)
Chris@16: {
Chris@16:   detail::all_gather_impl(comm, &in_value, 1, out_values, is_mpi_datatype<T>());
Chris@16: }
Chris@16: 
Chris@16: template<typename T>
Chris@16: void
Chris@16: all_gather(const communicator& comm, const T& in_value, 
Chris@16:            std::vector<T>& out_values)
Chris@16: {
Chris@16:   out_values.resize(comm.size());
Chris@16:   ::boost::mpi::all_gather(comm, &in_value, 1, &out_values[0]);
Chris@16: }
Chris@16: 
Chris@16: template<typename T>
Chris@16: inline void
Chris@16: all_gather(const communicator& comm, const T* in_values, int n, T* out_values)
Chris@16: {
Chris@16:   detail::all_gather_impl(comm, in_values, n, out_values, is_mpi_datatype<T>());
Chris@16: }
Chris@16: 
Chris@16: template<typename T>
Chris@16: void
Chris@16: all_gather(const communicator& comm, const T* in_values, int n,
Chris@16:            std::vector<T>& out_values)
Chris@16: {
Chris@16:   out_values.resize(comm.size() * n);
Chris@16:   ::boost::mpi::all_gather(comm, in_values, n, &out_values[0]);
Chris@16: }
Chris@16: 
Chris@16: } } // end namespace boost::mpi
Chris@16: 
Chris@16: #endif // BOOST_MPI_ALL_GATHER_HPP