update sources to v12.2.3

[ceph.git] / ceph / src / boost / boost / mpi / collectives / all_to_all.hpp

diff --git a/ceph/src/boost/boost/mpi/collectives/all_to_all.hpp b/ceph/src/boost/boost/mpi/collectives/all_to_all.hpp
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+// 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 4.8. All-to-all
+#ifndef BOOST_MPI_ALL_TO_ALL_HPP
+#define BOOST_MPI_ALL_TO_ALL_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/communicator.hpp>
+#include <boost/mpi/environment.hpp>
+#include <boost/assert.hpp>
+#include <boost/mpi/collectives_fwd.hpp>
+#include <boost/mpi/allocator.hpp>
+
+namespace boost { namespace mpi {
+          
+namespace detail {
+  // We're performaing an all-to-all with a type that has an
+  // associated MPI datatype, so we'll use MPI_Alltoall to do all of
+  // the work.
+  template<typename T>
+  void
+  all_to_all_impl(const communicator& comm, const T* in_values, int n, 
+                  T* out_values, mpl::true_)
+  {
+    MPI_Datatype type = get_mpi_datatype<T>(*in_values);
+    BOOST_MPI_CHECK_RESULT(MPI_Alltoall,
+                           (const_cast<T*>(in_values), n, type,
+                            out_values, n, type, comm));
+  }
+
+  // We're performing an all-to-all with 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_Alltoall, so
+  // we'll just have to send individual messages to the other
+  // processes.
+  template<typename T>
+  void
+  all_to_all_impl(const communicator& comm, const T* in_values, int n,
+                  T* out_values, mpl::false_)
+  {
+    int size = comm.size();
+    int rank = comm.rank();
+
+    // The amount of data to be sent to each process
+    std::vector<int> send_sizes(size);
+
+    // The displacements for each outgoing value.
+    std::vector<int> send_disps(size);
+
+    // The buffer that will store all of the outgoing values
+    std::vector<char, allocator<char> > outgoing;
+
+    // Pack the buffer with all of the outgoing values.
+    for (int dest = 0; dest < size; ++dest) {
+      // Keep track of the displacements
+      send_disps[dest] = outgoing.size();
+
+      // Our own value will never be transmitted, so don't pack it.
+      if (dest != rank) {
+        packed_oarchive oa(comm, outgoing);
+        for (int i = 0; i < n; ++i)
+          oa << in_values[dest * n + i];
+      }
+
+      // Keep track of the sizes
+      send_sizes[dest] = outgoing.size() - send_disps[dest];
+    }
+
+    // Determine how much data each process will receive.
+    std::vector<int> recv_sizes(size);
+    all_to_all(comm, send_sizes, recv_sizes);
+
+    // Prepare a buffer to receive the incoming data.
+    std::vector<int> recv_disps(size);
+    int sum = 0;
+    for (int src = 0; src < size; ++src) {
+      recv_disps[src] = sum;
+      sum += recv_sizes[src];
+    }
+    std::vector<char, allocator<char> > incoming(sum > 0? sum : 1);
+
+    // Make sure we don't try to reference an empty vector
+    if (outgoing.empty())
+      outgoing.push_back(0);
+
+    // Transmit the actual data
+    BOOST_MPI_CHECK_RESULT(MPI_Alltoallv,
+                           (&outgoing[0], &send_sizes[0],
+                            &send_disps[0], MPI_PACKED,
+                            &incoming[0], &recv_sizes[0],
+                            &recv_disps[0], MPI_PACKED,
+                            comm));
+
+    // Deserialize data from the iarchive
+    for (int src = 0; src < size; ++src) {
+      if (src == rank) 
+        std::copy(in_values + src * n, in_values + (src + 1) * n, 
+                  out_values + src * n);
+      else {
+        packed_iarchive ia(comm, incoming, boost::archive::no_header,
+                           recv_disps[src]);
+        for (int i = 0; i < n; ++i)
+          ia >> out_values[src * n + i];
+      }
+    }
+  }
+} // end namespace detail
+
+template<typename T>
+inline void
+all_to_all(const communicator& comm, const T* in_values, T* out_values)
+{
+  detail::all_to_all_impl(comm, in_values, 1, out_values, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void
+all_to_all(const communicator& comm, const std::vector<T>& in_values,
+           std::vector<T>& out_values)
+{
+  BOOST_ASSERT((int)in_values.size() == comm.size());
+  out_values.resize(comm.size());
+  ::boost::mpi::all_to_all(comm, &in_values[0], &out_values[0]);
+}
+
+template<typename T>
+inline void
+all_to_all(const communicator& comm, const T* in_values, int n, T* out_values)
+{
+  detail::all_to_all_impl(comm, in_values, n, out_values, is_mpi_datatype<T>());
+}
+
+template<typename T>
+void
+all_to_all(const communicator& comm, const std::vector<T>& in_values, int n,
+           std::vector<T>& out_values)
+{
+  BOOST_ASSERT((int)in_values.size() == comm.size() * n);
+  out_values.resize(comm.size() * n);
+  ::boost::mpi::all_to_all(comm, &in_values[0], n, &out_values[0]);
+}
+
+} } // end namespace boost::mpi
+
+#endif // BOOST_MPI_ALL_TO_ALL_HPP