ceph/src/boost/boost/property_map/parallel/global_index_map.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 #ifndef BOOST_PARALLEL_GLOBAL_INDEX_MAP_HPP
  10 #define BOOST_PARALLEL_GLOBAL_INDEX_MAP_HPP
  11
  12 #include <boost/property_map/property_map.hpp>
  13 #include <vector>
  14 #include <boost/shared_ptr.hpp>
  15
  16 namespace boost { namespace parallel {
  17
  18 template<typename IndexMap, typename GlobalMap>
  19 class global_index_map
  20 {
  21 public:
  22   typedef typename property_traits<IndexMap>::key_type key_type;
  23   typedef typename property_traits<IndexMap>::value_type value_type;
  24   typedef value_type reference;
  25   typedef readable_property_map_tag category;
  26
  27   template<typename ProcessGroup>
  28   global_index_map(ProcessGroup pg, value_type num_local_indices,
  29                    IndexMap index_map, GlobalMap global)
  30     : index_map(index_map), global(global)
  31   {
  32     typedef typename ProcessGroup::process_id_type process_id_type;
  33     starting_index.reset(new std::vector<value_type>(num_processes(pg) + 1));
  34     send(pg, 0, 0, num_local_indices);
  35     synchronize(pg);
  36
  37     // Populate starting_index in all processes
  38     if (process_id(pg) == 0) {
  39       (*starting_index)[0] = 0;
  40       for (process_id_type src = 0; src < num_processes(pg); ++src) {
  41         value_type n;
  42         receive(pg, src, 0, n);
  43         (*starting_index)[src + 1] = (*starting_index)[src] + n;
  44       }
  45       for (process_id_type dest = 1; dest < num_processes(pg); ++dest)
  46         send(pg, dest, 1, &starting_index->front(), num_processes(pg));
  47       synchronize(pg);
  48     } else {
  49       synchronize(pg);
  50       receive(pg, 0, 1, &starting_index->front(), num_processes(pg));
  51     }
  52   }
  53
  54   friend inline value_type
  55   get(const global_index_map& gim, const key_type& x)
  56   {
  57     using boost::get;
  58     return (*gim.starting_index)[get(gim.global, x).first]
  59            + get(gim.index_map, x);
  60   }
  61
  62 private:
  63   shared_ptr<std::vector<value_type> > starting_index;
  64   IndexMap index_map;
  65   GlobalMap global;
  66 };
  67
  68 } } // end namespace boost::parallel
  69
  70 #endif // BOOST_PARALLEL_GLOBAL_INDEX_MAP_HPP