osrm-backend/include/engine/routing_algorithms/many_to_many.hpp
2016-10-06 14:06:19 +02:00

293 lines
10 KiB
C++

#ifndef MANY_TO_MANY_ROUTING_HPP
#define MANY_TO_MANY_ROUTING_HPP
#include "engine/routing_algorithms/routing_base.hpp"
#include "engine/search_engine_data.hpp"
#include "util/typedefs.hpp"
#include <boost/assert.hpp>
#include <limits>
#include <memory>
#include <unordered_map>
#include <vector>
namespace osrm
{
namespace engine
{
namespace routing_algorithms
{
template <class DataFacadeT>
class ManyToManyRouting final
: public BasicRoutingInterface<DataFacadeT, ManyToManyRouting<DataFacadeT>>
{
using super = BasicRoutingInterface<DataFacadeT, ManyToManyRouting<DataFacadeT>>;
using QueryHeap = SearchEngineData::QueryHeap;
SearchEngineData &engine_working_data;
struct NodeBucket
{
unsigned target_id; // essentially a row in the distance matrix
EdgeWeight distance;
NodeBucket(const unsigned target_id, const EdgeWeight distance)
: target_id(target_id), distance(distance)
{
}
};
// FIXME This should be replaced by an std::unordered_multimap, though this needs benchmarking
using SearchSpaceWithBuckets = std::unordered_map<NodeID, std::vector<NodeBucket>>;
public:
ManyToManyRouting(SearchEngineData &engine_working_data)
: engine_working_data(engine_working_data)
{
}
std::vector<EdgeWeight> operator()(const DataFacadeT &facade,
const std::vector<PhantomNode> &phantom_nodes,
const std::vector<std::size_t> &source_indices,
const std::vector<std::size_t> &target_indices) const
{
const auto number_of_sources =
source_indices.empty() ? phantom_nodes.size() : source_indices.size();
const auto number_of_targets =
target_indices.empty() ? phantom_nodes.size() : target_indices.size();
const auto number_of_entries = number_of_sources * number_of_targets;
std::vector<EdgeWeight> result_table(number_of_entries,
std::numeric_limits<EdgeWeight>::max());
engine_working_data.InitializeOrClearFirstThreadLocalStorage(facade.GetNumberOfNodes());
QueryHeap &query_heap = *(engine_working_data.forward_heap_1);
SearchSpaceWithBuckets search_space_with_buckets;
unsigned column_idx = 0;
const auto search_target_phantom = [&](const PhantomNode &phantom) {
query_heap.Clear();
// insert target(s) at distance 0
if (phantom.forward_segment_id.enabled)
{
query_heap.Insert(phantom.forward_segment_id.id,
phantom.GetForwardWeightPlusOffset(),
phantom.forward_segment_id.id);
}
if (phantom.reverse_segment_id.enabled)
{
query_heap.Insert(phantom.reverse_segment_id.id,
phantom.GetReverseWeightPlusOffset(),
phantom.reverse_segment_id.id);
}
// explore search space
while (!query_heap.Empty())
{
BackwardRoutingStep(facade, column_idx, query_heap, search_space_with_buckets);
}
++column_idx;
};
// for each source do forward search
unsigned row_idx = 0;
const auto search_source_phantom = [&](const PhantomNode &phantom) {
query_heap.Clear();
// insert target(s) at distance 0
if (phantom.forward_segment_id.enabled)
{
query_heap.Insert(phantom.forward_segment_id.id,
-phantom.GetForwardWeightPlusOffset(),
phantom.forward_segment_id.id);
}
if (phantom.reverse_segment_id.enabled)
{
query_heap.Insert(phantom.reverse_segment_id.id,
-phantom.GetReverseWeightPlusOffset(),
phantom.reverse_segment_id.id);
}
// explore search space
while (!query_heap.Empty())
{
ForwardRoutingStep(facade,
row_idx,
number_of_targets,
query_heap,
search_space_with_buckets,
result_table);
}
++row_idx;
};
if (target_indices.empty())
{
for (const auto &phantom : phantom_nodes)
{
search_target_phantom(phantom);
}
}
else
{
for (const auto index : target_indices)
{
const auto &phantom = phantom_nodes[index];
search_target_phantom(phantom);
}
}
if (source_indices.empty())
{
for (const auto &phantom : phantom_nodes)
{
search_source_phantom(phantom);
}
}
else
{
for (const auto index : source_indices)
{
const auto &phantom = phantom_nodes[index];
search_source_phantom(phantom);
}
}
return result_table;
}
void ForwardRoutingStep(const DataFacadeT &facade,
const unsigned row_idx,
const unsigned number_of_targets,
QueryHeap &query_heap,
const SearchSpaceWithBuckets &search_space_with_buckets,
std::vector<EdgeWeight> &result_table) const
{
const NodeID node = query_heap.DeleteMin();
const int source_distance = query_heap.GetKey(node);
// check if each encountered node has an entry
const auto bucket_iterator = search_space_with_buckets.find(node);
// iterate bucket if there exists one
if (bucket_iterator != search_space_with_buckets.end())
{
const std::vector<NodeBucket> &bucket_list = bucket_iterator->second;
for (const NodeBucket &current_bucket : bucket_list)
{
// get target id from bucket entry
const unsigned column_idx = current_bucket.target_id;
const int target_distance = current_bucket.distance;
auto &current_distance = result_table[row_idx * number_of_targets + column_idx];
// check if new distance is better
const EdgeWeight new_distance = source_distance + target_distance;
if (new_distance < 0)
{
const EdgeWeight loop_weight = super::GetLoopWeight(facade, node);
const int new_distance_with_loop = new_distance + loop_weight;
if (loop_weight != INVALID_EDGE_WEIGHT && new_distance_with_loop >= 0)
{
current_distance = std::min(current_distance, new_distance_with_loop);
}
}
else if (new_distance < current_distance)
{
result_table[row_idx * number_of_targets + column_idx] = new_distance;
}
}
}
if (StallAtNode<true>(facade, node, source_distance, query_heap))
{
return;
}
RelaxOutgoingEdges<true>(facade, node, source_distance, query_heap);
}
void BackwardRoutingStep(const DataFacadeT &facade,
const unsigned column_idx,
QueryHeap &query_heap,
SearchSpaceWithBuckets &search_space_with_buckets) const
{
const NodeID node = query_heap.DeleteMin();
const int target_distance = query_heap.GetKey(node);
// store settled nodes in search space bucket
search_space_with_buckets[node].emplace_back(column_idx, target_distance);
if (StallAtNode<false>(facade, node, target_distance, query_heap))
{
return;
}
RelaxOutgoingEdges<false>(facade, node, target_distance, query_heap);
}
template <bool forward_direction>
inline void RelaxOutgoingEdges(const DataFacadeT &facade,
const NodeID node,
const EdgeWeight distance,
QueryHeap &query_heap) const
{
for (auto edge : facade.GetAdjacentEdgeRange(node))
{
const auto &data = facade.GetEdgeData(edge);
const bool direction_flag = (forward_direction ? data.forward : data.backward);
if (direction_flag)
{
const NodeID to = facade.GetTarget(edge);
const int edge_weight = data.distance;
BOOST_ASSERT_MSG(edge_weight > 0, "edge_weight invalid");
const int to_distance = distance + edge_weight;
// New Node discovered -> Add to Heap + Node Info Storage
if (!query_heap.WasInserted(to))
{
query_heap.Insert(to, to_distance, node);
}
// Found a shorter Path -> Update distance
else if (to_distance < query_heap.GetKey(to))
{
// new parent
query_heap.GetData(to).parent = node;
query_heap.DecreaseKey(to, to_distance);
}
}
}
}
// Stalling
template <bool forward_direction>
inline bool StallAtNode(const DataFacadeT &facade,
const NodeID node,
const EdgeWeight distance,
QueryHeap &query_heap) const
{
for (auto edge : facade.GetAdjacentEdgeRange(node))
{
const auto &data = facade.GetEdgeData(edge);
const bool reverse_flag = ((!forward_direction) ? data.forward : data.backward);
if (reverse_flag)
{
const NodeID to = facade.GetTarget(edge);
const int edge_weight = data.distance;
BOOST_ASSERT_MSG(edge_weight > 0, "edge_weight invalid");
if (query_heap.WasInserted(to))
{
if (query_heap.GetKey(to) + edge_weight < distance)
{
return true;
}
}
}
}
return false;
}
};
}
}
}
#endif