// Copyright 2004 The Trustees of Indiana University. // 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) // Authors: Douglas Gregor // Andrew Lumsdaine #ifndef BOOST_GRAPH_PARALLEL_BFS_HPP #define BOOST_GRAPH_PARALLEL_BFS_HPP #ifndef BOOST_GRAPH_USE_MPI #error "Parallel BGL files should not be included unless <boost/graph/use_mpi.hpp> has been included" #endif #include <boost/graph/breadth_first_search.hpp> #include <boost/graph/overloading.hpp> #include <boost/graph/distributed/concepts.hpp> #include <boost/graph/distributed/detail/filtered_queue.hpp> #include <boost/graph/distributed/queue.hpp> #include <boost/dynamic_bitset.hpp> #include <boost/pending/queue.hpp> #include <boost/graph/parallel/properties.hpp> #include <boost/graph/parallel/container_traits.hpp> namespace boost { namespace detail { /** @brief A unary predicate that decides when to push into a * breadth-first search queue. * * This predicate stores a color map that is used to determine * when to push. If it is provided with a key for which the color * is white, it darkens the color to gray and returns true (so * that the value will be pushed appropriately); if the color is * not white, it returns false so that the vertex will be * ignored. */ template<typename ColorMap> struct darken_and_push { typedef typename property_traits<ColorMap>::key_type argument_type; typedef bool result_type; explicit darken_and_push(const ColorMap& color) : color(color) { } bool operator()(const argument_type& value) const { typedef color_traits<typename property_traits<ColorMap>::value_type> Color; if (get(color, value) == Color::white()) { put(color, value, Color::gray()); return true; } else { return false; } } ColorMap color; }; template<typename IndexMap> struct has_not_been_seen { typedef bool result_type; has_not_been_seen() { } has_not_been_seen(std::size_t n, IndexMap index_map) : seen(n), index_map(index_map) {} template<typename Key> result_type operator()(Key key) { bool result = seen[get(index_map, key)]; seen[get(index_map, key)] = true; return !result; } void swap(has_not_been_seen& other) { using std::swap; swap(seen, other.seen); swap(index_map, other.index_map); } private: dynamic_bitset<> seen; IndexMap index_map; }; template<typename IndexMap> inline void swap(has_not_been_seen<IndexMap>& x, has_not_been_seen<IndexMap>& y) { x.swap(y); } template <class DistributedGraph, class ColorMap, class BFSVisitor, class BufferRef, class VertexIndexMap> inline void parallel_bfs_helper (DistributedGraph& g, typename graph_traits<DistributedGraph>::vertex_descriptor s, ColorMap color, BFSVisitor vis, BufferRef Q, VertexIndexMap) { set_property_map_role(vertex_color, color); color.set_consistency_model(0); breadth_first_search(g, s, Q.ref, vis, color); } template <class DistributedGraph, class ColorMap, class BFSVisitor, class VertexIndexMap> void parallel_bfs_helper (DistributedGraph& g, typename graph_traits<DistributedGraph>::vertex_descriptor s, ColorMap color, BFSVisitor vis, boost::param_not_found, VertexIndexMap vertex_index) { using boost::graph::parallel::process_group; typedef graph_traits<DistributedGraph> Traits; typedef typename Traits::vertex_descriptor Vertex; typedef typename boost::graph::parallel::process_group_type<DistributedGraph>::type process_group_type; set_property_map_role(vertex_color, color); color.set_consistency_model(0); // Buffer default typedef typename property_map<DistributedGraph, vertex_owner_t> ::const_type vertex_owner_map; typedef boost::graph::distributed::distributed_queue< process_group_type, vertex_owner_map, queue<Vertex>, detail::darken_and_push<ColorMap> > queue_t; queue_t Q(process_group(g), get(vertex_owner, g), detail::darken_and_push<ColorMap>(color)); breadth_first_search(g, s, Q, vis, color); } template <class DistributedGraph, class ColorMap, class BFSVisitor, class P, class T, class R> void bfs_helper (DistributedGraph& g, typename graph_traits<DistributedGraph>::vertex_descriptor s, ColorMap color, BFSVisitor vis, const bgl_named_params<P, T, R>& params, BOOST_GRAPH_ENABLE_IF_MODELS(DistributedGraph, distributed_graph_tag, void)*) { parallel_bfs_helper (g, s, color, vis, get_param(params, buffer_param_t()), choose_const_pmap(get_param(params, vertex_index), g, vertex_index)); } } } #endif // BOOST_GRAPH_PARALLEL_BFS_HPP