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// Copyright 2004, 2005 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: Nick Edmonds
// Andrew Lumsdaine
#ifndef BOOST_GRAPH_DISTRIBUTED_RMAT_GENERATOR_HPP
#define BOOST_GRAPH_DISTRIBUTED_RMAT_GENERATOR_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/assert.hpp>
#include <boost/graph/parallel/algorithm.hpp>
#include <boost/graph/parallel/process_group.hpp>
#include <math.h>
namespace boost {
// Memory-scalable (amount of memory required will scale down
// linearly as the number of processes increases) generator, which
// requires an MPI process group. Run-time is slightly worse than
// the unique rmat generator. Edge list generated is sorted and
// unique.
template<typename ProcessGroup, typename Distribution,
typename RandomGenerator, typename Graph>
class scalable_rmat_iterator
{
typedef typename graph_traits<Graph>::directed_category directed_category;
typedef typename graph_traits<Graph>::vertices_size_type vertices_size_type;
typedef typename graph_traits<Graph>::edges_size_type edges_size_type;
public:
typedef std::input_iterator_tag iterator_category;
typedef std::pair<vertices_size_type, vertices_size_type> value_type;
typedef const value_type& reference;
typedef const value_type* pointer;
typedef void difference_type;
// No argument constructor, set to terminating condition
scalable_rmat_iterator()
: gen(), done(true)
{ }
// Initialize for edge generation
scalable_rmat_iterator(ProcessGroup pg, Distribution distrib,
RandomGenerator& gen, vertices_size_type n,
edges_size_type m, double a, double b, double c,
double d, bool permute_vertices = true)
: gen(), done(false)
{
BOOST_ASSERT(a + b + c + d == 1);
int id = process_id(pg);
this->gen.reset(new uniform_01<RandomGenerator>(gen));
std::vector<vertices_size_type> vertexPermutation;
if (permute_vertices)
generate_permutation_vector(gen, vertexPermutation, n);
int SCALE = int(floor(log(double(n))/log(2.)));
boost::uniform_01<RandomGenerator> prob(gen);
std::map<value_type, bool> edge_map;
edges_size_type generated = 0, local_edges = 0;
do {
edges_size_type tossed = 0;
do {
vertices_size_type u, v;
boost::tie(u, v) = generate_edge(this->gen, n, SCALE, a, b, c, d);
if (permute_vertices) {
u = vertexPermutation[u];
v = vertexPermutation[v];
}
// Lowest vertex number always comes first (this
// means we don't have to worry about i->j and j->i
// being in the edge list)
if (u > v && is_same<directed_category, undirected_tag>::value)
std::swap(u, v);
if (distrib(u) == id || distrib(v) == id) {
if (edge_map.find(std::make_pair(u, v)) == edge_map.end()) {
edge_map[std::make_pair(u, v)] = true;
local_edges++;
} else {
tossed++;
// special case - if both u and v are on same
// proc, ++ twice, since we divide by two (to
// cover the two process case)
if (distrib(u) == id && distrib(v) == id)
tossed++;
}
}
generated++;
} while (generated < m);
tossed = all_reduce(pg, tossed, boost::parallel::sum<vertices_size_type>());
generated -= (tossed / 2);
} while (generated < m);
// NGE - Asking for more than n^2 edges will result in an infinite loop here
// Asking for a value too close to n^2 edges may as well
values.reserve(local_edges);
typename std::map<value_type, bool>::reverse_iterator em_end = edge_map.rend();
for (typename std::map<value_type, bool>::reverse_iterator em_i = edge_map.rbegin();
em_i != em_end ;
++em_i) {
values.push_back(em_i->first);
}
current = values.back();
values.pop_back();
}
reference operator*() const { return current; }
pointer operator->() const { return ¤t; }
scalable_rmat_iterator& operator++()
{
if (!values.empty()) {
current = values.back();
values.pop_back();
} else
done = true;
return *this;
}
scalable_rmat_iterator operator++(int)
{
scalable_rmat_iterator temp(*this);
++(*this);
return temp;
}
bool operator==(const scalable_rmat_iterator& other) const
{
return values.empty() && other.values.empty() && done && other.done;
}
bool operator!=(const scalable_rmat_iterator& other) const
{ return !(*this == other); }
private:
// Parameters
shared_ptr<uniform_01<RandomGenerator> > gen;
// Internal data structures
std::vector<value_type> values;
value_type current;
bool done;
};
} // end namespace boost
#endif // BOOST_GRAPH_DISTRIBUTED_RMAT_GENERATOR_HPP
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