ceph/src/boost/libs/graph_parallel/include/boost/graph/parallel/detail/inplace_all_to_all.hpp

   1 // Copyright 2005 The Trustees of Indiana University.
   2
   3 // Use, modification and distribution is subject to the Boost Software
   4 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6
   7 //  Authors: Douglas Gregor
   8 //           Andrew Lumsdaine
   9
  10 #ifndef BOOST_GRAPH_PARALLEL_INPLACE_ALL_TO_ALL_HPP
  11 #define BOOST_GRAPH_PARALLEL_INPLACE_ALL_TO_ALL_HPP
  12
  13 #ifndef BOOST_GRAPH_USE_MPI
  14 #error "Parallel BGL files should not be included unless <boost/graph/use_mpi.hpp> has been included"
  15 #endif
  16
  17 //
  18 // Implements the inplace all-to-all communication algorithm.
  19 //
  20 #include <vector>
  21 #include <iterator>
  22
  23 namespace boost { namespace parallel {
  24
  25 template<typename ProcessGroup, typename T>
  26 // where {LinearProcessGroup<ProcessGroup>, MessagingProcessGroup<ProcessGroup>}
  27 void
  28 inplace_all_to_all(ProcessGroup pg,
  29                    const std::vector<std::vector<T> >& outgoing,
  30                    std::vector<std::vector<T> >& incoming)
  31 {
  32   typedef typename std::vector<T>::size_type size_type;
  33
  34   typedef typename ProcessGroup::process_size_type process_size_type;
  35   typedef typename ProcessGroup::process_id_type process_id_type;
  36
  37   process_size_type p = num_processes(pg);
  38
  39   // Make sure there are no straggling messages
  40   synchronize(pg);
  41
  42   // Send along the count (always) and the data (if count > 0)
  43   for (process_id_type dest = 0; dest < p; ++dest) {
  44     if (dest != process_id(pg)) {
  45       send(pg, dest, 0, outgoing[dest].size());
  46       if (!outgoing[dest].empty())
  47         send(pg, dest, 1, &outgoing[dest].front(), outgoing[dest].size());
  48     }
  49   }
  50
  51   // Make sure all of the data gets transferred
  52   synchronize(pg);
  53
  54   // Receive the sizes and data
  55   for (process_id_type source = 0; source < p; ++source) {
  56     if (source != process_id(pg)) {
  57       size_type size;
  58       receive(pg, source, 0, size);
  59       incoming[source].resize(size);
  60       if (size > 0)
  61         receive(pg, source, 1, &incoming[source].front(), size);
  62     } else if (&incoming != &outgoing) {
  63       incoming[source] = outgoing[source];
  64     }
  65   }
  66 }
  67
  68 template<typename ProcessGroup, typename T>
  69 // where {LinearProcessGroup<ProcessGroup>, MessagingProcessGroup<ProcessGroup>}
  70 void
  71 inplace_all_to_all(ProcessGroup pg, std::vector<std::vector<T> >& data)
  72 {
  73   inplace_all_to_all(pg, data, data);
  74 }
  75
  76 } } // end namespace boost::parallel
  77
  78 #endif // BOOST_GRAPH_PARALLEL_INPLACE_ALL_TO_ALL_HPP