comparison DEPENDENCIES/generic/include/boost/mpi/collectives/scatter.hpp @ 16:2665513ce2d3

Add boost headers

+// Copyright (C) 2005, 2006 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 4.6. Scatter
+#ifndef BOOST_MPI_SCATTER_HPP
+#define BOOST_MPI_SCATTER_HPP
+
+#include <boost/mpi/exception.hpp>
+#include <boost/mpi/datatype.hpp>
+#include <vector>
+#include <boost/mpi/packed_oarchive.hpp>
+#include <boost/mpi/packed_iarchive.hpp>
+#include <boost/mpi/detail/point_to_point.hpp>
+#include <boost/mpi/communicator.hpp>
+#include <boost/mpi/environment.hpp>
+#include <boost/assert.hpp>
+
+namespace boost { namespace mpi {
+
+namespace detail {
+  // We're scattering from the root for a type that has an associated MPI
+  // datatype, so we'll use MPI_Scatter to do all of the work.
+  template<typename T>
+  void
+  scatter_impl(const communicator& comm, const T* in_values, T* out_values, 
+               int n, int root, mpl::true_)
+  {
+    MPI_Datatype type = get_mpi_datatype<T>(*in_values);
+    BOOST_MPI_CHECK_RESULT(MPI_Scatter,
+                           (const_cast<T*>(in_values), n, type,
+                            out_values, n, type, root, comm));
+  }
+
+  // We're scattering from a non-root for a type that has an associated MPI
+  // datatype, so we'll use MPI_Scatter to do all of the work.
+  template<typename T>
+  void
+  scatter_impl(const communicator& comm, T* out_values, int n, int root, 
+               mpl::true_)
+  {
+    MPI_Datatype type = get_mpi_datatype<T>(*out_values);
+    BOOST_MPI_CHECK_RESULT(MPI_Scatter,
+                           (0, n, type,
+                            out_values, n, type,
+                            root, comm));
+  }
+
+  // We're scattering from the root for a type that does not have an
+  // associated MPI datatype, so we'll need to serialize
+  // it. Unfortunately, this means that we cannot use MPI_Scatter, so
+  // we'll just have the root send individual messages to the other
+  // processes.
+  template<typename T>
+  void
+  scatter_impl(const communicator& comm, const T* in_values, T* out_values, 
+               int n, int root, mpl::false_)
+  {
+    int tag = environment::collectives_tag();
+    int size = comm.size();
+
+    for (int dest = 0; dest < size; ++dest) {
+      if (dest == root) {
+        // Our own values will never be transmitted: just copy them.
+        std::copy(in_values + dest * n, in_values + (dest + 1) * n, out_values);
+      } else {
+        // Send archive
+        packed_oarchive oa(comm);
+        for (int i = 0; i < n; ++i)
+          oa << in_values[dest * n + i];
+        detail::packed_archive_send(comm, dest, tag, oa);
+      }
+    }
+  }
+
+  // We're scattering to a non-root for a type that does not have an
+  // associated MPI datatype, so we'll need to de-serialize
+  // it. Unfortunately, this means that we cannot use MPI_Scatter, so
+  // we'll just have all of the non-root nodes send individual
+  // messages to the root.
+  template<typename T>
+  void
+  scatter_impl(const communicator& comm, T* out_values, int n, int root, 
+               mpl::false_)
+  {
+    int tag = environment::collectives_tag();
+
+    packed_iarchive ia(comm);
+    MPI_Status status;
+    detail::packed_archive_recv(comm, root, tag, ia, status);
+    for (int i = 0; i < n; ++i)
+      ia >> out_values[i];
+  }
+} // end namespace detail
+
+template<typename T>
+void
+scatter(const communicator& comm, const T* in_values, T& out_value, int root)
+{
+  if (comm.rank() == root)
+    detail::scatter_impl(comm, in_values, &out_value, 1, root, 
+                         is_mpi_datatype<T>());
+  else
+    detail::scatter_impl(comm, &out_value, 1, root, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void
+scatter(const communicator& comm, const std::vector<T>& in_values, T& out_value,
+        int root)
+{
+  if (comm.rank() == root)
+    ::boost::mpi::scatter<T>(comm, &in_values[0], out_value, root);
+  else
+    ::boost::mpi::scatter<T>(comm, static_cast<const T*>(0), out_value, 
+                             root);
+}
+
+template<typename T>
+void scatter(const communicator& comm, T& out_value, int root)
+{
+  BOOST_ASSERT(comm.rank() != root);
+  detail::scatter_impl(comm, &out_value, 1, root, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void
+scatter(const communicator& comm, const T* in_values, T* out_values, int n,
+        int root)
+{
+  if (comm.rank() == root)
+    detail::scatter_impl(comm, in_values, out_values, n, root,
+                         is_mpi_datatype<T>());
+  else
+    detail::scatter_impl(comm, out_values, n, root, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void
+scatter(const communicator& comm, const std::vector<T>& in_values, 
+        T* out_values, int n, int root)
+{
+  if (comm.rank() == root)
+    ::boost::mpi::scatter(comm, &in_values[0], out_values, n, root);
+  else
+    ::boost::mpi::scatter(comm, static_cast<const T*>(0), out_values, 
+                                    n, root);
+}
+
+template<typename T>
+void scatter(const communicator& comm, T* out_values, int n, int root)
+{
+  BOOST_ASSERT(comm.rank() != root);
+  detail::scatter_impl(comm, out_values, n, root, is_mpi_datatype<T>());
+}
+
+} } // end namespace boost::mpi
+
+#endif // BOOST_MPI_SCATTER_HPP