Added boost header

test/external/boost/mpi/collectives/gather.hpp

@@ -0,0 +1,147 @@
+// 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 4.5. Gather
+#ifndef BOOST_MPI_GATHER_HPP
+#define BOOST_MPI_GATHER_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 gathering at the root 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
+  gather_impl(const communicator& comm, const T* in_values, int n, 
+              T* out_values, int root, mpl::true_)
+  {
+    MPI_Datatype type = get_mpi_datatype<T>(*in_values);
+    BOOST_MPI_CHECK_RESULT(MPI_Gather,
+                           (const_cast<T*>(in_values), n, type,
+                            out_values, n, type, root, comm));
+  }
+
+  // We're gathering from a non-root 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
+  gather_impl(const communicator& comm, const T* in_values, int n, int root, 
+              mpl::true_)
+  {
+    MPI_Datatype type = get_mpi_datatype<T>(*in_values);
+    BOOST_MPI_CHECK_RESULT(MPI_Gather,
+                           (const_cast<T*>(in_values), n, type,
+                            0, n, type, root, comm));
+  }
+
+  // We're gathering at 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_Gather, so
+  // we'll just have all of the non-root nodes send individual
+  // messages to the root.
+  template<typename T>
+  void
+  gather_impl(const communicator& comm, const T* in_values, int n, 
+              T* out_values, int root, mpl::false_)
+  {
+    int tag = environment::collectives_tag();
+    int size = comm.size();
+
+    for (int src = 0; src < size; ++src) {
+      if (src == root)
+        std::copy(in_values, in_values + n, out_values + n * src);
+      else
+        comm.recv(src, tag, out_values + n * src, n);
+    }
+  }
+
+  // We're gathering at a non-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_Gather, so
+  // we'll just have all of the non-root nodes send individual
+  // messages to the root.
+  template<typename T>
+  void
+  gather_impl(const communicator& comm, const T* in_values, int n, int root, 
+              mpl::false_)
+  {
+    int tag = environment::collectives_tag();
+    comm.send(root, tag, in_values, n);
+  }
+} // end namespace detail
+
+template<typename T>
+void
+gather(const communicator& comm, const T& in_value, T* out_values, int root)
+{
+  if (comm.rank() == root)
+    detail::gather_impl(comm, &in_value, 1, out_values, root, 
+                        is_mpi_datatype<T>());
+  else
+    detail::gather_impl(comm, &in_value, 1, root, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void gather(const communicator& comm, const T& in_value, int root)
+{
+  BOOST_ASSERT(comm.rank() != root);
+  detail::gather_impl(comm, &in_value, 1, root, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void
+gather(const communicator& comm, const T& in_value, std::vector<T>& out_values,
+       int root)
+{
+  if (comm.rank() == root) {
+    out_values.resize(comm.size());
+    ::boost::mpi::gather(comm, in_value, &out_values[0], root);
+  } else {
+    ::boost::mpi::gather(comm, in_value, root);
+  }
+}
+
+template<typename T>
+void
+gather(const communicator& comm, const T* in_values, int n, T* out_values, 
+       int root)
+{
+  if (comm.rank() == root)
+    detail::gather_impl(comm, in_values, n, out_values, root, 
+                        is_mpi_datatype<T>());
+  else
+    detail::gather_impl(comm, in_values, n, root, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void
+gather(const communicator& comm, const T* in_values, int n, 
+       std::vector<T>& out_values, int root)
+{
+  ::boost::mpi::gather(comm, in_values, n, &out_values[0], root);
+}
+
+template<typename T>
+void gather(const communicator& comm, const T* in_values, int n, int root)
+{
+  BOOST_ASSERT(comm.rank() != root);
+  detail::gather_impl(comm, in_values, n, root, is_mpi_datatype<T>());
+}
+
+
+} } // end namespace boost::mpi
+
+#endif // BOOST_MPI_GATHER_HPP