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// 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::mpl::true_)
{
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
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