// Copyright (C) 2004-2008 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: Douglas Gregor
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// Andrew Lumsdaine
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#ifndef BOOST_GRAPH_DISTRIBUTED_DFS_HPP
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#define BOOST_GRAPH_DISTRIBUTED_DFS_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/graph/graph_traits.hpp>
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#include <boost/property_map/property_map.hpp>
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#include <boost/graph/overloading.hpp>
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#include <boost/graph/properties.hpp>
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#include <boost/graph/distributed/concepts.hpp>
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#include <boost/static_assert.hpp>
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#include <boost/assert.hpp>
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#include <boost/graph/parallel/process_group.hpp>
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#include <boost/graph/parallel/container_traits.hpp>
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namespace boost {
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namespace graph { namespace distributed { namespace detail {
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template<typename DistributedGraph, typename ColorMap, typename ParentMap,
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typename ExploreMap, typename VertexIndexMap, typename DFSVisitor>
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class parallel_dfs
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{
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typedef typename graph_traits<DistributedGraph>::vertex_iterator
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vertex_iterator;
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typedef typename graph_traits<DistributedGraph>::vertex_descriptor
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vertex_descriptor;
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typedef typename graph_traits<DistributedGraph>::out_edge_iterator
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out_edge_iterator;
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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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/**
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* The first vertex in the pair is the local node (i) and the
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* second vertex in the pair is the (possibly remote) node (j).
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*/
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typedef boost::parallel::detail::untracked_pair<vertex_descriptor, vertex_descriptor> vertex_pair;
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typedef typename property_traits<ColorMap>::value_type color_type;
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typedef color_traits<color_type> Color;
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// Message types
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enum { discover_msg = 10, return_msg = 50, visited_msg = 100 , done_msg = 150};
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public:
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parallel_dfs(const DistributedGraph& g, ColorMap color,
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ParentMap parent, ExploreMap explore,
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VertexIndexMap index_map, DFSVisitor vis)
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: g(g), color(color), parent(parent), explore(explore),
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index_map(index_map), vis(vis), pg(process_group(g)),
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owner(get(vertex_owner, g)), next_out_edge(num_vertices(g))
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{ }
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void run(vertex_descriptor s)
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{
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vertex_iterator vi, vi_end;
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for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi) {
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put(color, *vi, Color::white());
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put(parent, *vi, *vi);
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put(explore, *vi, *vi);
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next_out_edge[get(index_map, *vi)] = out_edges(*vi, g).first;
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vis.initialize_vertex(*vi, g);
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}
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vis.start_vertex(s, g);
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if (get(owner, s) == process_id(pg)) {
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send_oob(pg, get(owner, s), discover_msg, vertex_pair(s, s));
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}
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bool done = false;
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while (!done) {
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std::pair<process_id_type, int> msg = *pg.poll(true);
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switch (msg.second) {
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case discover_msg:
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{
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vertex_pair p;
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receive_oob(pg, msg.first, msg.second, p);
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if (p.first != p.second) {
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// delete j from nomessage(j)
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if (get(color, p.second) != Color::black())
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local_put(color, p.second, Color::gray());
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if (recover(p)) break;
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}
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if (get(color, p.first) == Color::white()) {
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put(color, p.first, Color::gray());
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put(parent, p.first, p.second);
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vis.discover_vertex(p.first, g);
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if (shift_center_of_activity(p.first)) break;
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out_edge_iterator ei, ei_end;
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for (boost::tie(ei,ei_end) = out_edges(p.first, g); ei != ei_end; ++ei)
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{
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// Notify everyone who may not know that the source
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// vertex has been visited. They can then mark the
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// corresponding color map entry gray.
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if (get(parent, p.first) != target(*ei, g)
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&& get(explore, p.first) != target(*ei, g)) {
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vertex_pair visit(target(*ei, g), p.first);
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send_oob(pg, get(owner, target(*ei, g)), visited_msg, visit);
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}
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}
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}
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}
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break;
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case visited_msg:
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{
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vertex_pair p;
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receive_oob(pg, msg.first, msg.second, p);
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// delete j from nomessage(j)
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if (get(color, p.second) != Color::black())
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local_put(color, p.second, Color::gray());
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recover(p);
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}
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break;
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case return_msg:
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{
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vertex_pair p;
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receive_oob(pg, msg.first, msg.second, p);
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// delete j from nomessage(i)
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local_put(color, p.second, Color::black());
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shift_center_of_activity(p.first);
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}
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break;
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case done_msg:
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{
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receive_oob(pg, msg.first, msg.second, done);
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// Propagate done message downward in tree
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done = true;
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process_id_type id = process_id(pg);
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process_id_type left = 2*id + 1;
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process_id_type right = left + 1;
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if (left < num_processes(pg))
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send_oob(pg, left, done_msg, done);
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if (right < num_processes(pg))
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send_oob(pg, right, done_msg, done);
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}
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break;
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default:
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BOOST_ASSERT(false);
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}
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}
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}
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private:
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bool recover(const vertex_pair& p)
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{
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if (get(explore, p.first) == p.second) {
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return shift_center_of_activity(p.first);
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}
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else
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return false;
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}
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bool shift_center_of_activity(vertex_descriptor i)
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{
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for (out_edge_iterator ei = next_out_edge[get(index_map, i)],
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ei_end = out_edges(i, g).second;
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ei != ei_end; ++ei) {
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vis.examine_edge(*ei, g);
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vertex_descriptor k = target(*ei, g);
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color_type target_color = get(color, k);
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if (target_color == Color::black()) vis.forward_or_cross_edge(*ei, g);
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else if (target_color == Color::gray()) vis.back_edge(*ei, g);
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else {
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put(explore, i, k);
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vis.tree_edge(*ei, g);
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vertex_pair p(k, i);
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send_oob(pg, get(owner, k), discover_msg, p);
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next_out_edge[get(index_map, i)] = ++ei;
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return false;
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}
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}
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next_out_edge[get(index_map, i)] = out_edges(i, g).second;
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put(explore, i, i);
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put(color, i, Color::black());
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vis.finish_vertex(i, g);
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if (get(parent, i) == i) {
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send_oob(pg, 0, done_msg, true);
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return true;
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}
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else {
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vertex_pair ret(get(parent, i), i);
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send_oob(pg, get(owner, ret.first), return_msg, ret);
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}
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return false;
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}
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const DistributedGraph& g;
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ColorMap color;
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ParentMap parent;
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ExploreMap explore;
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VertexIndexMap index_map;
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DFSVisitor vis;
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process_group_type pg;
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typename property_map<DistributedGraph, vertex_owner_t>::const_type owner;
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std::vector<out_edge_iterator> next_out_edge;
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};
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} // end namespace detail
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template<typename DistributedGraph, typename ColorMap, typename ParentMap,
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typename ExploreMap, typename VertexIndexMap, typename DFSVisitor>
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void
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tsin_depth_first_visit
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(const DistributedGraph& g,
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typename graph_traits<DistributedGraph>::vertex_descriptor s,
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DFSVisitor vis, ColorMap color, ParentMap parent, ExploreMap explore,
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VertexIndexMap index_map)
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{
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typedef typename graph_traits<DistributedGraph>::directed_category
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directed_category;
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BOOST_STATIC_ASSERT(
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(is_convertible<directed_category, undirected_tag>::value));
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set_property_map_role(vertex_color, color);
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graph::distributed::detail::parallel_dfs
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<DistributedGraph, ColorMap, ParentMap, ExploreMap, VertexIndexMap,
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DFSVisitor> do_dfs(g, color, parent, explore, index_map, vis);
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do_dfs.run(s);
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using boost::graph::parallel::process_group;
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synchronize(process_group(g));
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}
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template<typename DistributedGraph, typename DFSVisitor,
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typename VertexIndexMap>
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void
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tsin_depth_first_visit
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(const DistributedGraph& g,
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typename graph_traits<DistributedGraph>::vertex_descriptor s,
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DFSVisitor vis,
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VertexIndexMap index_map)
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{
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typedef typename graph_traits<DistributedGraph>::vertex_descriptor
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vertex_descriptor;
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std::vector<default_color_type> colors(num_vertices(g));
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std::vector<vertex_descriptor> parent(num_vertices(g));
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std::vector<vertex_descriptor> explore(num_vertices(g));
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tsin_depth_first_visit
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(g, s,
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vis,
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make_iterator_property_map(colors.begin(), index_map),
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make_iterator_property_map(parent.begin(), index_map),
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make_iterator_property_map(explore.begin(), index_map),
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index_map);
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}
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template<typename DistributedGraph, typename DFSVisitor,
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typename VertexIndexMap>
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void
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tsin_depth_first_visit
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(const DistributedGraph& g,
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typename graph_traits<DistributedGraph>::vertex_descriptor s,
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DFSVisitor vis)
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{
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tsin_depth_first_visit(g, s, vis, get(vertex_index, g));
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}
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} // end namespace distributed
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using distributed::tsin_depth_first_visit;
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} // end namespace graph
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template<typename DistributedGraph, typename DFSVisitor>
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void
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depth_first_visit
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(const DistributedGraph& g,
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typename graph_traits<DistributedGraph>::vertex_descriptor s,
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DFSVisitor vis)
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{
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graph::tsin_depth_first_visit(g, s, vis, get(vertex_index, g));
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}
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} // end namespace boost
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#endif // BOOST_GRAPH_DISTRIBUTED_DFS_HPP
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