// Copyright (C) 2004-2006 The Trustees of Indiana University.
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// Use, modification and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Authors: Nick Edmonds
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// Douglas Gregor
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// Andrew Lumsdaine
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#ifndef BOOST_GRAPH_PARALLEL_CC_HPP
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#define BOOST_GRAPH_PARALLEL_CC_HPP
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#ifndef BOOST_GRAPH_USE_MPI
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#error "Parallel BGL files should not be included unless <boost/graph/use_mpi.hpp> has been included"
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#endif
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#include <boost/detail/is_sorted.hpp>
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#include <boost/assert.hpp>
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#include <boost/property_map/property_map.hpp>
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#include <boost/property_map/parallel/caching_property_map.hpp>
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#include <boost/graph/parallel/algorithm.hpp>
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#include <boost/pending/indirect_cmp.hpp>
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#include <boost/graph/graph_traits.hpp>
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#include <boost/graph/overloading.hpp>
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#include <boost/graph/distributed/concepts.hpp>
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#include <boost/graph/parallel/properties.hpp>
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#include <boost/graph/distributed/local_subgraph.hpp>
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#include <boost/graph/connected_components.hpp>
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#include <boost/graph/named_function_params.hpp>
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#include <boost/graph/parallel/process_group.hpp>
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#include <boost/optional.hpp>
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#include <functional>
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#include <algorithm>
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#include <vector>
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#include <list>
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#include <boost/graph/parallel/container_traits.hpp>
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#include <boost/graph/iteration_macros.hpp>
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#define PBGL_IN_PLACE_MERGE /* In place merge instead of sorting */
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//#define PBGL_SORT_ASSERT /* Assert sorted for in place merge */
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/* Explicit sychronization in pointer doubling step? */
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#define PBGL_EXPLICIT_SYNCH
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//#define PBGL_CONSTRUCT_METAGRAPH
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#ifdef PBGL_CONSTRUCT_METAGRAPH
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# define MAX_VERTICES_IN_METAGRAPH 10000
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#endif
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namespace boost { namespace graph { namespace distributed {
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namespace cc_detail {
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enum connected_components_message {
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edges_msg, req_parents_msg, parents_msg, root_adj_msg
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};
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template <typename Vertex>
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struct metaVertex {
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metaVertex() {}
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metaVertex(const Vertex& v) : name(v) {}
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template<typename Archiver>
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void serialize(Archiver& ar, const unsigned int /*version*/)
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{
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ar & name;
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}
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Vertex name;
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};
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#ifdef PBGL_CONSTRUCT_METAGRAPH
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// Build meta-graph on result of local connected components
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template <typename Graph, typename ParentMap, typename RootIterator,
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typename AdjacencyMap>
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void
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build_local_metagraph(const Graph& g, ParentMap p, RootIterator r,
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RootIterator r_end, AdjacencyMap& adj)
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{
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// TODO: Static assert that AdjacencyMap::value_type is std::vector<vertex_descriptor>
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typedef typename boost::graph::parallel::process_group_type<Graph>::type
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process_group_type;
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typedef typename process_group_type::process_id_type process_id_type;
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typedef typename graph_traits<Graph>::vertex_descriptor vertex_descriptor;
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BOOST_STATIC_ASSERT((is_same<typename AdjacencyMap::mapped_type,
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std::vector<vertex_descriptor> >::value));
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using boost::graph::parallel::process_group;
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process_group_type pg = process_group(g);
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process_id_type id = process_id(pg);
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if (id != 0) {
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// Send component roots and their associated edges to P0
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for ( ; r != r_end; ++r ) {
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std::vector<vertex_descriptor> adjs(1, *r); // Root
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adjs.reserve(adjs.size() + adj[*r].size());
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for (typename std::vector<vertex_descriptor>::iterator iter = adj[*r].begin();
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iter != adj[*r].end(); ++iter)
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adjs.push_back(get(p, *iter)); // Adjacencies
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send(pg, 0, root_adj_msg, adjs);
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}
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}
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synchronize(pg);
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if (id == 0) {
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typedef metaVertex<vertex_descriptor> VertexProperties;
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typedef boost::adjacency_list<vecS, vecS, undirectedS,
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VertexProperties> metaGraph;
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typedef typename graph_traits<metaGraph>::vertex_descriptor
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meta_vertex_descriptor;
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std::map<vertex_descriptor, meta_vertex_descriptor> vertex_map;
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std::vector<std::pair<vertex_descriptor, vertex_descriptor> > edges;
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// Receive remote roots and edges
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while (optional<std::pair<process_id_type, int> > m = probe(pg)) {
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BOOST_ASSERT(m->second == root_adj_msg);
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std::vector<vertex_descriptor> adjs;
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receive(pg, m->first, m->second, adjs);
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vertex_map[adjs[0]] = graph_traits<metaGraph>::null_vertex();
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for (typename std::vector<vertex_descriptor>::iterator iter
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= ++adjs.begin(); iter != adjs.end(); ++iter)
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edges.push_back(std::make_pair(adjs[0], *iter));
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}
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// Add local roots and edges
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for ( ; r != r_end; ++r ) {
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vertex_map[*r] = graph_traits<metaGraph>::null_vertex();
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edges.reserve(edges.size() + adj[*r].size());
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for (typename std::vector<vertex_descriptor>::iterator iter = adj[*r].begin();
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iter != adj[*r].end(); ++iter)
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edges.push_back(std::make_pair(*r, get(p, *iter)));
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}
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// Build local meta-graph
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metaGraph mg;
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// Add vertices with property to map back to distributed graph vertex
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for (typename std::map<vertex_descriptor, meta_vertex_descriptor>::iterator
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iter = vertex_map.begin(); iter != vertex_map.end(); ++iter)
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vertex_map[iter->first]
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= add_vertex(metaVertex<vertex_descriptor>(iter->first), mg);
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// Build meta-vertex map
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typename property_map<metaGraph, vertex_descriptor VertexProperties::*>::type
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metaVertexMap = get(&VertexProperties::name, mg);
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typename std::vector<std::pair<vertex_descriptor, vertex_descriptor> >
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::iterator edge_iter = edges.begin();
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for ( ; edge_iter != edges.end(); ++edge_iter)
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add_edge(vertex_map[edge_iter->first], vertex_map[edge_iter->second], mg);
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edges.clear();
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// Call connected_components on it
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typedef typename property_map<metaGraph, vertex_index_t>::type
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meta_index_map_type;
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meta_index_map_type meta_index = get(vertex_index, mg);
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std::vector<std::size_t> mg_component_vec(num_vertices(mg));
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typedef iterator_property_map<std::vector<std::size_t>::iterator,
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meta_index_map_type>
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meta_components_map_type;
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meta_components_map_type mg_component(mg_component_vec.begin(),
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meta_index);
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std::size_t num_comp = connected_components(mg, mg_component);
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// Update Parent pointers
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std::vector<meta_vertex_descriptor> roots(num_comp, graph_traits<metaGraph>::null_vertex());
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BGL_FORALL_VERTICES_T(v, mg, metaGraph) {
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size_t component = get(mg_component, v);
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if (roots[component] == graph_traits<metaGraph>::null_vertex() ||
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get(meta_index, v) < get(meta_index, roots[component]))
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roots[component] = v;
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}
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// Set all the local parent pointers
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BGL_FORALL_VERTICES_T(v, mg, metaGraph) {
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// Problem in value being put (3rd parameter)
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put(p, get(metaVertexMap, v), get(metaVertexMap, roots[get(mg_component, v)]));
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}
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}
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synchronize(p);
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}
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#endif
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/* Function object used to remove internal vertices and vertices >
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the current vertex from the adjacent vertex lists at each
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root */
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template <typename Vertex, typename ParentMap>
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class cull_adjacency_list
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{
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public:
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cull_adjacency_list(const Vertex v, const ParentMap p) : v(v), p(p) {}
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bool operator() (const Vertex x) { return (get(p, x) == v || x == v); }
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private:
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const Vertex v;
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const ParentMap p;
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};
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/* Comparison operator used to choose targets for hooking s.t. vertices
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that are hooked to are evenly distributed across processors */
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template <typename OwnerMap, typename LocalMap>
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class hashed_vertex_compare
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{
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public:
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hashed_vertex_compare (const OwnerMap& o, const LocalMap& l)
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: owner(o), local(l) { }
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template <typename Vertex>
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bool operator() (const Vertex x, const Vertex y)
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{
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if (get(local, x) < get(local, y))
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return true;
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else if (get(local, x) == get(local, y))
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return (get(owner, x) < get(owner, y));
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return false;
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}
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private:
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OwnerMap owner;
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LocalMap local;
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};
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#ifdef PBGL_EXPLICIT_SYNCH
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template <typename Graph, typename ParentMap, typename VertexList>
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void
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request_parent_map_entries(const Graph& g, ParentMap p,
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std::vector<VertexList>& parent_requests)
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{
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typedef typename boost::graph::parallel::process_group_type<Graph>
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::type process_group_type;
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typedef typename process_group_type::process_id_type process_id_type;
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typedef typename graph_traits<Graph>::vertex_descriptor
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vertex_descriptor;
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process_group_type pg = process_group(g);
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/*
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This should probably be send_oob_with_reply, especially when Dave
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finishes prefetch-batching
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*/
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// Send root requests
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for (process_id_type i = 0; i < num_processes(pg); ++i) {
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if (!parent_requests[i].empty()) {
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std::vector<vertex_descriptor> reqs(parent_requests[i].begin(),
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parent_requests[i].end());
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send(pg, i, req_parents_msg, reqs);
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}
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}
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synchronize(pg);
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// Receive root requests and reply to them
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while (optional<std::pair<process_id_type, int> > m = probe(pg)) {
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std::vector<vertex_descriptor> requests;
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receive(pg, m->first, m->second, requests);
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for (std::size_t i = 0; i < requests.size(); ++i)
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requests[i] = get(p, requests[i]);
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send(pg, m->first, parents_msg, requests);
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}
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synchronize(pg);
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// Receive requested parents
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std::vector<vertex_descriptor> responses;
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for (process_id_type i = 0; i < num_processes(pg); ++i) {
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if (!parent_requests[i].empty()) {
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receive(pg, i, parents_msg, responses);
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std::size_t parent_idx = 0;
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for (typename VertexList::iterator v = parent_requests[i].begin();
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v != parent_requests[i].end(); ++v, ++parent_idx)
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put(p, *v, responses[parent_idx]);
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}
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}
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}
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#endif
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template<typename DistributedGraph, typename ParentMap>
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void
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parallel_connected_components(DistributedGraph& g, ParentMap p)
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{
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using boost::connected_components;
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typedef typename graph_traits<DistributedGraph>::adjacency_iterator
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adjacency_iterator;
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typedef typename graph_traits<DistributedGraph>::vertex_descriptor
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vertex_descriptor;
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typedef typename boost::graph::parallel::process_group_type<DistributedGraph>
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::type process_group_type;
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typedef typename process_group_type::process_id_type process_id_type;
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using boost::graph::parallel::process_group;
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process_group_type pg = process_group(g);
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process_id_type id = process_id(pg);
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// TODO (NGE): Should old_roots, roots, and completed_roots be std::list
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adjacency_iterator av1, av2;
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std::vector<vertex_descriptor> old_roots;
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typename std::vector<vertex_descriptor>::iterator liter;
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typename std::vector<vertex_descriptor>::iterator aliter;
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typename std::map<vertex_descriptor,
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std::vector<vertex_descriptor> > adj;
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typedef typename property_map<DistributedGraph, vertex_owner_t>::const_type
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OwnerMap;
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OwnerMap owner = get(vertex_owner, g);
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typedef typename property_map<DistributedGraph, vertex_local_t>::const_type
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LocalMap;
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LocalMap local = get(vertex_local, g);
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// We need to hold on to all of the parent pointers
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p.set_max_ghost_cells(0);
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//
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// STAGE 1 : Compute local components
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//
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local_subgraph<const DistributedGraph> ls(g);
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typedef typename property_map<local_subgraph<const DistributedGraph>,
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vertex_index_t>::type local_index_map_type;
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local_index_map_type local_index = get(vertex_index, ls);
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// Compute local connected components
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std::vector<std::size_t> ls_components_vec(num_vertices(ls));
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typedef iterator_property_map<std::vector<std::size_t>::iterator,
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local_index_map_type>
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ls_components_map_type;
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ls_components_map_type ls_component(ls_components_vec.begin(),
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local_index);
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std::size_t num_comp = connected_components(ls, ls_component);
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std::vector<vertex_descriptor>
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roots(num_comp, graph_traits<DistributedGraph>::null_vertex());
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BGL_FORALL_VERTICES_T(v, g, DistributedGraph) {
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size_t component = get(ls_component, v);
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if (roots[component] == graph_traits<DistributedGraph>::null_vertex() ||
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get(local_index, v) < get(local_index, roots[component]))
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roots[component] = v;
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}
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// Set all the local parent pointers
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BGL_FORALL_VERTICES_T(v, g, DistributedGraph) {
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put(p, v, roots[get(ls_component, v)]);
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}
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if (num_processes(pg) == 1) return;
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// Build adjacency list for all roots
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BGL_FORALL_VERTICES_T(v, g, DistributedGraph) {
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std::vector<vertex_descriptor>& my_adj = adj[get(p, v)];
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for (boost::tie(av1, av2) = adjacent_vertices(v, g);
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av1 != av2; ++av1) {
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if (get(owner, *av1) != id) my_adj.push_back(*av1);
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}
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}
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// For all vertices adjacent to a local vertex get p(v)
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for ( liter = roots.begin(); liter != roots.end(); ++liter ) {
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std::vector<vertex_descriptor>& my_adj = adj[*liter];
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for ( aliter = my_adj.begin(); aliter != my_adj.end(); ++aliter )
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request(p, *aliter);
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}
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synchronize(p);
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// Update adjacency list at root to make sure all adjacent
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// vertices are roots of remote components
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for ( liter = roots.begin(); liter != roots.end(); ++liter )
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{
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std::vector<vertex_descriptor>& my_adj = adj[*liter];
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for ( aliter = my_adj.begin(); aliter != my_adj.end(); ++aliter )
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*aliter = get(p, *aliter);
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my_adj.erase
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(std::remove_if(my_adj.begin(), my_adj.end(),
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cull_adjacency_list<vertex_descriptor,
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ParentMap>(*liter, p) ),
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my_adj.end());
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// This sort needs to be here to make sure the initial
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// adjacency list is sorted
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std::sort(my_adj.begin(), my_adj.end(), std::less<vertex_descriptor>());
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my_adj.erase(std::unique(my_adj.begin(), my_adj.end()), my_adj.end());
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}
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// Get p(v) for the new adjacent roots
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p.clear();
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for ( liter = roots.begin(); liter != roots.end(); ++liter ) {
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std::vector<vertex_descriptor>& my_adj = adj[*liter];
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for ( aliter = my_adj.begin(); aliter != my_adj.end(); ++aliter )
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request(p, *aliter);
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}
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#ifdef PBGL_EXPLICIT_SYNCH
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synchronize(p);
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#endif
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// Lastly, remove roots with no adjacent vertices, this is
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// unnecessary but will speed up sparse graphs
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for ( liter = roots.begin(); liter != roots.end(); /*in loop*/)
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{
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if ( adj[*liter].empty() )
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liter = roots.erase(liter);
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else
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++liter;
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}
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#ifdef PBGL_CONSTRUCT_METAGRAPH
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/* TODO: If the number of roots is sufficiently small, we can
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use a 'problem folding' approach like we do in MST
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to gather all the roots and their adjacencies on one proc
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and solve for the connected components of the meta-graph */
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using boost::parallel::all_reduce;
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std::size_t num_roots = all_reduce(pg, roots.size(), std::plus<std::size_t>());
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if (num_roots < MAX_VERTICES_IN_METAGRAPH) {
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build_local_metagraph(g, p, roots.begin(), roots.end(), adj);
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// For each vertex in g, p(v) = p(p(v)), assign parent of leaf
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// vertices from first step to final parent
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BGL_FORALL_VERTICES_T(v, g, DistributedGraph) {
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put(p, v, get(p, get(p, v)));
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}
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synchronize(p);
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return;
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}
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#endif
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//
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// Parallel Phase
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//
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std::vector<vertex_descriptor> completed_roots;
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hashed_vertex_compare<OwnerMap, LocalMap> v_compare(owner, local);
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bool any_hooked;
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vertex_descriptor new_root;
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std::size_t steps = 0;
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do {
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++steps;
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// Pull in new parents for hooking phase
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synchronize(p);
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//
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// Hooking
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//
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bool hooked = false;
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completed_roots.clear();
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for ( liter = roots.begin(); liter != roots.end(); )
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{
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new_root = graph_traits<DistributedGraph>::null_vertex();
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std::vector<vertex_descriptor>& my_adj = adj[*liter];
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for ( aliter = my_adj.begin(); aliter != my_adj.end(); ++aliter )
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// try to hook to better adjacent vertex
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if ( v_compare( get(p, *aliter), *liter ) )
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new_root = get(p, *aliter);
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if ( new_root != graph_traits<DistributedGraph>::null_vertex() )
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{
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hooked = true;
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put(p, *liter, new_root);
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old_roots.push_back(*liter);
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completed_roots.push_back(*liter);
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liter = roots.erase(liter);
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}
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else
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++liter;
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}
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//
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// Pointer jumping, perform until new roots determined
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//
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// TODO: Implement cycle reduction rules to reduce this from
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// O(n) to O(log n) [n = cycle length]
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bool all_done;
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std::size_t parent_root_count;
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std::size_t double_steps = 0;
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do {
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++double_steps;
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#ifndef PBGL_EXPLICIT_SYNCH
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// Get p(p(v)) for all old roots, and p(v) for all current roots
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for ( liter = old_roots.begin(); liter != old_roots.end(); ++liter )
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request(p, get(p, *liter));
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synchronize(p);
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#else
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// Build root requests
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typedef std::set<vertex_descriptor> VertexSet;
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std::vector<VertexSet> parent_requests(num_processes(pg));
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for ( liter = old_roots.begin(); liter != old_roots.end(); ++liter )
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{
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vertex_descriptor p1 = *liter;
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if (get(owner, p1) != id) parent_requests[get(owner, p1)].insert(p1);
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vertex_descriptor p2 = get(p, p1);
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if (get(owner, p2) != id) parent_requests[get(owner, p2)].insert(p2);
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}
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request_parent_map_entries(g, p, parent_requests);
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#endif
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// Perform a pointer jumping step on all old roots
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for ( liter = old_roots.begin(); liter != old_roots.end(); ++liter )
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put(p, *liter, get(p, get(p, *liter)));
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// make sure the parent of all old roots is itself a root
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parent_root_count = 0;
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for ( liter = old_roots.begin(); liter != old_roots.end(); ++liter )
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if ( get(p, *liter) == get(p, get(p, *liter)) )
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parent_root_count++;
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bool done = parent_root_count == old_roots.size();
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all_reduce(pg, &done, &done+1, &all_done,
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std::logical_and<bool>());
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} while ( !all_done );
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#ifdef PARALLEL_BGL_DEBUG
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if (id == 0) std::cerr << double_steps << " doubling steps.\n";
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#endif
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//
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// Add adjacent vertices of just completed roots to adjacent
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// vertex list at new parent
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//
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typename std::vector<vertex_descriptor> outgoing_edges;
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for ( liter = completed_roots.begin(); liter != completed_roots.end();
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++liter )
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{
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vertex_descriptor new_parent = get(p, *liter);
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if ( get(owner, new_parent) == id )
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{
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std::vector<vertex_descriptor>& my_adj = adj[new_parent];
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my_adj.reserve(my_adj.size() + adj[*liter].size());
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my_adj.insert( my_adj.end(),
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adj[*liter].begin(), adj[*liter].end() );
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#ifdef PBGL_IN_PLACE_MERGE
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#ifdef PBGL_SORT_ASSERT
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BOOST_ASSERT(::boost::detail::is_sorted(my_adj.begin(),
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my_adj.end() - adj[*liter].size(),
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std::less<vertex_descriptor>()));
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BOOST_ASSERT(::boost::detail::is_sorted(my_adj.end() - adj[*liter].size(),
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my_adj.end(),
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std::less<vertex_descriptor>()));
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#endif
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std::inplace_merge(my_adj.begin(),
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my_adj.end() - adj[*liter].size(),
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my_adj.end(),
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std::less<vertex_descriptor>());
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#endif
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}
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else if ( adj[*liter].begin() != adj[*liter].end() )
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{
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outgoing_edges.clear();
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outgoing_edges.reserve(adj[*liter].size() + 1);
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// First element is the destination of the adjacency list
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outgoing_edges.push_back(new_parent);
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outgoing_edges.insert(outgoing_edges.end(),
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adj[*liter].begin(), adj[*liter].end() );
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send(pg, get(owner, new_parent), edges_msg, outgoing_edges);
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adj[*liter].clear();
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}
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}
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synchronize(pg);
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// Receive edges sent by remote nodes and add them to the
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// indicated vertex's adjacency list
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while (optional<std::pair<process_id_type, int> > m
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= probe(pg))
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{
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std::vector<vertex_descriptor> incoming_edges;
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receive(pg, m->first, edges_msg, incoming_edges);
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typename std::vector<vertex_descriptor>::iterator aviter
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= incoming_edges.begin();
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++aviter;
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std::vector<vertex_descriptor>& my_adj = adj[incoming_edges[0]];
|
|
my_adj.reserve(my_adj.size() + incoming_edges.size() - 1);
|
my_adj.insert( my_adj.end(), aviter, incoming_edges.end() );
|
|
#ifdef PBGL_IN_PLACE_MERGE
|
std::size_t num_incoming_edges = incoming_edges.size();
|
#ifdef PBGL_SORT_ASSERT
|
BOOST_ASSERT(::boost::detail::is_sorted(my_adj.begin(),
|
my_adj.end() - (num_incoming_edges-1),
|
std::less<vertex_descriptor>()));
|
BOOST_ASSERT(::boost::detail::is_sorted(my_adj.end() - (num_incoming_edges-1),
|
my_adj.end(),
|
std::less<vertex_descriptor>()));
|
#endif
|
std::inplace_merge(my_adj.begin(),
|
my_adj.end() - (num_incoming_edges - 1),
|
my_adj.end(),
|
std::less<vertex_descriptor>());
|
#endif
|
|
}
|
|
|
// Remove any adjacent vertices that are in the same component
|
// as a root from that root's list
|
for ( liter = roots.begin(); liter != roots.end(); ++liter )
|
{
|
// We can probably get away without sorting and removing
|
// duplicates Though sorting *may* cause root
|
// determination to occur faster by choosing the root with
|
// the most potential to hook to at each step
|
std::vector<vertex_descriptor>& my_adj = adj[*liter];
|
my_adj.erase
|
(std::remove_if(my_adj.begin(), my_adj.end(),
|
cull_adjacency_list<vertex_descriptor,
|
ParentMap>(*liter, p) ),
|
my_adj.end());
|
#ifndef PBGL_IN_PLACE_MERGE
|
std::sort(my_adj.begin(), my_adj.end(),
|
std::less<vertex_descriptor>() );
|
#endif
|
my_adj.erase(std::unique(my_adj.begin(), my_adj.end()), my_adj.end());
|
}
|
|
// Reduce result of empty root list test
|
all_reduce(pg, &hooked, &hooked+1, &any_hooked,
|
std::logical_or<bool>());
|
} while ( any_hooked );
|
#ifdef PARALLEL_BGL_DEBUG
|
if (id == 0) std::cerr << steps << " iterations.\n";
|
#endif
|
//
|
// Finalize
|
//
|
|
// For each vertex in g, p(v) = p(p(v)), assign parent of leaf
|
// vertices from first step to final parent
|
BGL_FORALL_VERTICES_T(v, g, DistributedGraph) {
|
put(p, v, get(p, get(p, v)));
|
}
|
|
synchronize(p);
|
}
|
|
} // end namespace cc_detail
|
|
template<typename Graph, typename ParentMap, typename ComponentMap>
|
typename property_traits<ComponentMap>::value_type
|
number_components_from_parents(const Graph& g, ParentMap p, ComponentMap c)
|
{
|
typedef typename graph_traits<Graph>::vertex_descriptor
|
vertex_descriptor;
|
typedef typename boost::graph::parallel::process_group_type<Graph>::type
|
process_group_type;
|
typedef typename property_traits<ComponentMap>::value_type
|
ComponentMapType;
|
|
process_group_type pg = process_group(g);
|
|
/* Build list of roots */
|
std::vector<vertex_descriptor> my_roots, all_roots;
|
|
BGL_FORALL_VERTICES_T(v, g, Graph) {
|
if( std::find( my_roots.begin(), my_roots.end(), get(p, v) )
|
== my_roots.end() )
|
my_roots.push_back( get(p, v) );
|
}
|
|
all_gather(pg, my_roots.begin(), my_roots.end(), all_roots);
|
|
/* Number components */
|
std::map<vertex_descriptor, ComponentMapType> comp_numbers;
|
ComponentMapType c_num = 0;
|
|
// Compute component numbers
|
for (std::size_t i = 0; i < all_roots.size(); i++ )
|
if ( comp_numbers.count(all_roots[i]) == 0 )
|
comp_numbers[all_roots[i]] = c_num++;
|
|
// Broadcast component numbers
|
BGL_FORALL_VERTICES_T(v, g, Graph) {
|
put( c, v, comp_numbers[get(p, v)] );
|
}
|
|
// Broadcast number of components
|
if (process_id(pg) == 0) {
|
typedef typename process_group_type::process_size_type
|
process_size_type;
|
for (process_size_type dest = 1, n = num_processes(pg);
|
dest != n; ++dest)
|
send(pg, dest, 0, c_num);
|
}
|
synchronize(pg);
|
|
if (process_id(pg) != 0) receive(pg, 0, 0, c_num);
|
|
synchronize(c);
|
|
return c_num;
|
}
|
|
template<typename Graph, typename ParentMap>
|
int
|
number_components_from_parents(const Graph& g, ParentMap p,
|
dummy_property_map)
|
{
|
using boost::parallel::all_reduce;
|
|
// Count local roots.
|
int num_roots = 0;
|
BGL_FORALL_VERTICES_T(v, g, Graph)
|
if (get(p, v) == v) ++num_roots;
|
return all_reduce(g.process_group(), num_roots, std::plus<int>());
|
}
|
|
template<typename Graph, typename ComponentMap, typename ParentMap>
|
typename property_traits<ComponentMap>::value_type
|
connected_components
|
(const Graph& g, ComponentMap c, ParentMap p
|
BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, distributed_graph_tag))
|
{
|
cc_detail::parallel_connected_components(g, p);
|
return number_components_from_parents(g, p, c);
|
}
|
|
/* Construct ParentMap by default */
|
template<typename Graph, typename ComponentMap>
|
typename property_traits<ComponentMap>::value_type
|
connected_components
|
( const Graph& g, ComponentMap c
|
BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, distributed_graph_tag) )
|
{
|
typedef typename graph_traits<Graph>::vertex_descriptor vertex_descriptor;
|
|
std::vector<vertex_descriptor> x(num_vertices(g));
|
|
return connected_components
|
(g, c,
|
make_iterator_property_map(x.begin(), get(vertex_index, g)));
|
}
|
} // end namespace distributed
|
|
using distributed::connected_components;
|
} // end namespace graph
|
|
using graph::distributed::connected_components;
|
} // end namespace boost
|
|
#endif // BOOST_GRAPH_PARALLEL_CC_HPP
|
