broadcast.cpp
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// Copyright 2005 Douglas Gregor.
// 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 4.4. Broadcast
#include <boost/mpi/config.hpp>
#include <boost/mpi/collectives/broadcast.hpp>
#include <boost/mpi/skeleton_and_content.hpp>
#include <boost/mpi/detail/point_to_point.hpp>
#include <boost/mpi/environment.hpp>
#include <cassert>
namespace boost { namespace mpi {
template<>
void
broadcast<const packed_oarchive>(const communicator& comm,
const packed_oarchive& oa,
int root)
{
// Only the root can broadcast the packed_oarchive
assert(comm.rank() == root);
int size = comm.size();
if (size < 2) return;
// Determine maximum tag value
int tag = environment::collectives_tag();
// Broadcast data to all nodes
std::vector<request> requests(size-1);
std::vector<request>::iterator it = requests.begin();
for (int dest = 0; dest < size; ++dest) {
if (dest != root) {
*it++ = detail::packed_archive_isend(comm, dest, tag, oa);
}
}
wait_all(requests.begin(), requests.end());
}
template<>
void
broadcast<packed_oarchive>(const communicator& comm, packed_oarchive& oa,
int root)
{
broadcast(comm, const_cast<const packed_oarchive&>(oa), root);
}
template<>
void
broadcast<packed_iarchive>(const communicator& comm, packed_iarchive& ia,
int root)
{
int size = comm.size();
if (size < 2) return;
// Determine maximum tag value
int tag = environment::collectives_tag();
// Receive data from the root.
if (comm.rank() != root) {
MPI_Status status;
detail::packed_archive_recv(comm, root, tag, ia, status);
} else {
// Broadcast data to all nodes
std::vector<request> requests(size-1);
std::vector<request>::iterator it = requests.begin();
for (int dest = 0; dest < size; ++dest) {
if (dest != root) {
*it++ = detail::packed_archive_isend(comm, dest, tag, ia);
}
}
wait_all(requests.begin(), requests.end());
}
}
template<>
void
broadcast<const packed_skeleton_oarchive>(const communicator& comm,
const packed_skeleton_oarchive& oa,
int root)
{
broadcast(comm, oa.get_skeleton(), root);
}
template<>
void
broadcast<packed_skeleton_oarchive>(const communicator& comm,
packed_skeleton_oarchive& oa, int root)
{
broadcast(comm, oa.get_skeleton(), root);
}
template<>
void
broadcast<packed_skeleton_iarchive>(const communicator& comm,
packed_skeleton_iarchive& ia, int root)
{
broadcast(comm, ia.get_skeleton(), root);
}
template<>
void broadcast<content>(const communicator& comm, content& c, int root)
{
broadcast(comm, const_cast<const content&>(c), root);
}
template<>
void broadcast<const content>(const communicator& comm, const content& c,
int root)
{
#if defined(BOOST_MPI_BCAST_BOTTOM_WORKS_FINE)
BOOST_MPI_CHECK_RESULT(MPI_Bcast,
(MPI_BOTTOM, 1, c.get_mpi_datatype(),
root, comm));
#else
if (comm.size() < 2)
return;
// Some versions of LAM/MPI behave badly when broadcasting using
// MPI_BOTTOM, so we'll instead use manual send/recv operations.
if (comm.rank() == root) {
for (int p = 0; p < comm.size(); ++p) {
if (p != root) {
BOOST_MPI_CHECK_RESULT(MPI_Send,
(MPI_BOTTOM, 1, c.get_mpi_datatype(),
p, environment::collectives_tag(), comm));
}
}
} else {
BOOST_MPI_CHECK_RESULT(MPI_Recv,
(MPI_BOTTOM, 1, c.get_mpi_datatype(),
root, environment::collectives_tag(),
comm, MPI_STATUS_IGNORE));
}
#endif
}
} } // end namespace boost::mpi