boost/mpi/collectives/scatterv.hpp
// Copyright (C) 2011 Júlio Hoffimann.
// 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 4.6. Scatterv
#ifndef BOOST_MPI_SCATTERV_HPP
#define BOOST_MPI_SCATTERV_HPP
#include <boost/scoped_array.hpp>
#include <boost/mpi/collectives/scatter.hpp>
#include <boost/mpi/detail/offsets.hpp>
#include <boost/mpi/detail/antiques.hpp>
namespace boost { namespace mpi {
namespace detail {
//////////////////////////////////////////////
/// Implementation for MPI primitive types ///
//////////////////////////////////////////////
// We're scattering from the root for a type that has an associated MPI
// datatype, so we'll use MPI_Scatterv to do all of the work.
template<typename T>
void
scatterv_impl(const communicator& comm, const T* in_values, T* out_values, int out_size,
const int* sizes, const int* displs, int root, mpl::true_)
{
assert(!sizes || out_size == sizes[comm.rank()]);
assert(bool(sizes) == bool(in_values));
scoped_array<int> new_offsets_mem(make_offsets(comm, sizes, displs, root));
if (new_offsets_mem) displs = new_offsets_mem.get();
MPI_Datatype type = get_mpi_datatype<T>(*in_values);
BOOST_MPI_CHECK_RESULT(MPI_Scatterv,
(const_cast<T*>(in_values), const_cast<int*>(sizes),
const_cast<int*>(displs), type,
out_values, out_size, type, root, comm));
}
// We're scattering from a non-root for a type that has an associated MPI
// datatype, so we'll use MPI_Scatterv to do all of the work.
template<typename T>
void
scatterv_impl(const communicator& comm, T* out_values, int out_size, int root,
mpl::true_ is_mpi_type)
{
scatterv_impl(comm, (T const*)0, out_values, out_size,
(const int*)0, (const int*)0, root, is_mpi_type);
}
//////////////////////////////////////////////////
/// Implementation for non MPI primitive types ///
//////////////////////////////////////////////////
// We're scattering from the root for a type that does not have an
// associated MPI datatype, so we'll need to serialize it.
template<typename T>
void
scatterv_impl(const communicator& comm, const T* in_values, T* out_values, int out_size,
int const* sizes, int const* displs, int root, mpl::false_)
{
packed_oarchive::buffer_type sendbuf;
bool is_root = comm.rank() == root;
int nproc = comm.size();
std::vector<int> archsizes;
if (is_root) {
assert(out_size == sizes[comm.rank()]);
archsizes.resize(nproc);
std::vector<int> skipped;
if (displs) {
skipped.resize(nproc);
offsets2skipped(sizes, displs, c_data(skipped), nproc);
displs = c_data(skipped);
}
fill_scatter_sendbuf(comm, in_values, sizes, (int const*)0, sendbuf, archsizes);
}
dispatch_scatter_sendbuf(comm, sendbuf, archsizes, (T const*)0, out_values, out_size, root);
}
// We're scattering to a non-root for a type that does not have an
// associated MPI datatype. input data not needed.
// it.
template<typename T>
void
scatterv_impl(const communicator& comm, T* out_values, int n, int root,
mpl::false_ isnt_mpi_type)
{
assert(root != comm.rank());
scatterv_impl(comm, (T const*)0, out_values, n, (int const*)0, (int const*)0, root, isnt_mpi_type);
}
} // end namespace detail
template<typename T>
void
scatterv(const communicator& comm, const T* in_values,
const std::vector<int>& sizes, const std::vector<int>& displs,
T* out_values, int out_size, int root)
{
using detail::c_data;
detail::scatterv_impl(comm, in_values, out_values, out_size, c_data(sizes), c_data(displs),
root, is_mpi_datatype<T>());
}
template<typename T>
void
scatterv(const communicator& comm, const std::vector<T>& in_values,
const std::vector<int>& sizes, const std::vector<int>& displs,
T* out_values, int out_size, int root)
{
using detail::c_data;
::boost::mpi::scatterv(comm, c_data(in_values), sizes, displs,
out_values, out_size, root);
}
template<typename T>
void scatterv(const communicator& comm, T* out_values, int out_size, int root)
{
BOOST_ASSERT(comm.rank() != root);
detail::scatterv_impl(comm, out_values, out_size, root, is_mpi_datatype<T>());
}
///////////////////////
// common use versions
///////////////////////
template<typename T>
void
scatterv(const communicator& comm, const T* in_values,
const std::vector<int>& sizes, T* out_values, int root)
{
using detail::c_data;
detail::scatterv_impl(comm, in_values, out_values, sizes[comm.rank()],
c_data(sizes), (int const*)0,
root, is_mpi_datatype<T>());
}
template<typename T>
void
scatterv(const communicator& comm, const std::vector<T>& in_values,
const std::vector<int>& sizes, T* out_values, int root)
{
::boost::mpi::scatterv(comm, &in_values[0], sizes, out_values, root);
}
template<typename T>
void
scatterv(const communicator& comm, const T* in_values,
T* out_values, int n, int root)
{
detail::scatterv_impl(comm, in_values, out_values, n, (int const*)0, (int const*)0,
root, is_mpi_datatype<T>());
}
template<typename T>
void
scatterv(const communicator& comm, const std::vector<T>& in_values,
T* out_values, int out_size, int root)
{
::boost::mpi::scatterv(comm, &in_values[0], out_values, out_size, root);
}
} } // end namespace boost::mpi
#endif // BOOST_MPI_SCATTERV_HPP