#ifndef ALTERNATIVE_PATH_ROUTING_HPP
#define ALTERNATIVE_PATH_ROUTING_HPP
#include "engine/routing_algorithms/routing_base.hpp"
#include "engine/search_engine_data.hpp"
#include "util/integer_range.hpp"
#include <boost/assert.hpp>
#include <algorithm>
#include <iterator>
#include <unordered_map>
#include <unordered_set>
#include <vector>
namespace osrm
{
namespace engine
{
namespace routing_algorithms
{
const double VIAPATH_ALPHA = 0.10;
const double VIAPATH_EPSILON = 0.15; // alternative at most 15% longer
const double VIAPATH_GAMMA = 0.75; // alternative shares at most 75% with the shortest.
template <class DataFacadeT>
class AlternativeRouting final
: private BasicRoutingInterface<DataFacadeT, AlternativeRouting<DataFacadeT>>
{
using super = BasicRoutingInterface<DataFacadeT, AlternativeRouting<DataFacadeT>>;
using EdgeData = typename DataFacadeT::EdgeData;
using QueryHeap = SearchEngineData::QueryHeap;
using SearchSpaceEdge = std::pair<NodeID, NodeID>;
struct RankedCandidateNode
{
RankedCandidateNode(const NodeID node, const int length, const int sharing)
: node(node), length(length), sharing(sharing)
{
}
NodeID node;
int length;
int sharing;
bool operator<(const RankedCandidateNode &other) const
{
return (2 * length + sharing) < (2 * other.length + other.sharing);
}
};
DataFacadeT *facade;
SearchEngineData &engine_working_data;
public:
AlternativeRouting(DataFacadeT *facade, SearchEngineData &engine_working_data)
: super(facade), facade(facade), engine_working_data(engine_working_data)
{
}
virtual ~AlternativeRouting() {}
void operator()(const PhantomNodes &phantom_node_pair, InternalRouteResult &raw_route_data)
{
std::vector<NodeID> alternative_path;
std::vector<NodeID> via_node_candidate_list;
std::vector<SearchSpaceEdge> forward_search_space;
std::vector<SearchSpaceEdge> reverse_search_space;
// Init queues, semi-expensive because access to TSS invokes a sys-call
engine_working_data.InitializeOrClearFirstThreadLocalStorage(
super::facade->GetNumberOfNodes());
engine_working_data.InitializeOrClearSecondThreadLocalStorage(
super::facade->GetNumberOfNodes());
engine_working_data.InitializeOrClearThirdThreadLocalStorage(
super::facade->GetNumberOfNodes());
QueryHeap &forward_heap1 = *(engine_working_data.forward_heap_1);
QueryHeap &reverse_heap1 = *(engine_working_data.reverse_heap_1);
QueryHeap &forward_heap2 = *(engine_working_data.forward_heap_2);
QueryHeap &reverse_heap2 = *(engine_working_data.reverse_heap_2);
int upper_bound_to_shortest_path_distance = INVALID_EDGE_WEIGHT;
NodeID middle_node = SPECIAL_NODEID;
const EdgeWeight min_edge_offset =
std::min(-phantom_node_pair.source_phantom.GetForwardWeightPlusOffset(),
-phantom_node_pair.source_phantom.GetReverseWeightPlusOffset());
if (phantom_node_pair.source_phantom.forward_node_id != SPECIAL_NODEID)
{
// util::SimpleLogger().Write(logDEBUG) << "fwd-a insert: " <<
// phantom_node_pair.source_phantom.forward_node_id << ", w: " <<
// -phantom_node_pair.source_phantom.GetForwardWeightPlusOffset();
forward_heap1.Insert(phantom_node_pair.source_phantom.forward_node_id,
-phantom_node_pair.source_phantom.GetForwardWeightPlusOffset(),
phantom_node_pair.source_phantom.forward_node_id);
}
if (phantom_node_pair.source_phantom.reverse_node_id != SPECIAL_NODEID)
{
// util::SimpleLogger().Write(logDEBUG) << "fwd-b insert: " <<
// phantom_node_pair.source_phantom.reverse_node_id << ", w: " <<
// -phantom_node_pair.source_phantom.GetReverseWeightPlusOffset();
forward_heap1.Insert(phantom_node_pair.source_phantom.reverse_node_id,
-phantom_node_pair.source_phantom.GetReverseWeightPlusOffset(),
phantom_node_pair.source_phantom.reverse_node_id);
}
if (phantom_node_pair.target_phantom.forward_node_id != SPECIAL_NODEID)
{
// util::SimpleLogger().Write(logDEBUG) << "rev-a insert: " <<
// phantom_node_pair.target_phantom.forward_node_id << ", w: " <<
// phantom_node_pair.target_phantom.GetForwardWeightPlusOffset();
reverse_heap1.Insert(phantom_node_pair.target_phantom.forward_node_id,
phantom_node_pair.target_phantom.GetForwardWeightPlusOffset(),
phantom_node_pair.target_phantom.forward_node_id);
}
if (phantom_node_pair.target_phantom.reverse_node_id != SPECIAL_NODEID)
{
// util::SimpleLogger().Write(logDEBUG) << "rev-b insert: " <<
// phantom_node_pair.target_phantom.reverse_node_id << ", w: " <<
// phantom_node_pair.target_phantom.GetReverseWeightPlusOffset();
reverse_heap1.Insert(phantom_node_pair.target_phantom.reverse_node_id,
phantom_node_pair.target_phantom.GetReverseWeightPlusOffset(),
phantom_node_pair.target_phantom.reverse_node_id);
}
// search from s and t till new_min/(1+epsilon) > length_of_shortest_path
while (0 < (forward_heap1.Size() + reverse_heap1.Size()))
{
if (0 < forward_heap1.Size())
{
AlternativeRoutingStep<true>(forward_heap1, reverse_heap1, &middle_node,
&upper_bound_to_shortest_path_distance,
via_node_candidate_list, forward_search_space,
min_edge_offset);
}
if (0 < reverse_heap1.Size())
{
AlternativeRoutingStep<false>(forward_heap1, reverse_heap1, &middle_node,
&upper_bound_to_shortest_path_distance,
via_node_candidate_list, reverse_search_space,
min_edge_offset);
}
}
if (INVALID_EDGE_WEIGHT == upper_bound_to_shortest_path_distance)
{
return;
}
std::sort(begin(via_node_candidate_list), end(via_node_candidate_list));
auto unique_end = std::unique(begin(via_node_candidate_list), end(via_node_candidate_list));
via_node_candidate_list.resize(unique_end - begin(via_node_candidate_list));
std::vector<NodeID> packed_forward_path;
std::vector<NodeID> packed_reverse_path;
const bool path_is_a_loop =
upper_bound_to_shortest_path_distance !=
forward_heap1.GetKey(middle_node) + reverse_heap1.GetKey(middle_node);
if (path_is_a_loop)
{
// Self Loop
BOOST_ASSERT(forward_heap1.GetData(middle_node).parent == middle_node &&
reverse_heap1.GetData(middle_node).parent == middle_node);
packed_forward_path.push_back(middle_node);
packed_forward_path.push_back(middle_node);
}
else
{
super::RetrievePackedPathFromSingleHeap(forward_heap1, middle_node,
packed_forward_path);
super::RetrievePackedPathFromSingleHeap(reverse_heap1, middle_node,
packed_reverse_path);
}
// this set is is used as an indicator if a node is on the shortest path
std::unordered_set<NodeID> nodes_in_path(packed_forward_path.size() +
packed_reverse_path.size());
nodes_in_path.insert(packed_forward_path.begin(), packed_forward_path.end());
nodes_in_path.insert(middle_node);
nodes_in_path.insert(packed_reverse_path.begin(), packed_reverse_path.end());
std::unordered_map<NodeID, int> approximated_forward_sharing;
std::unordered_map<NodeID, int> approximated_reverse_sharing;
// sweep over search space, compute forward sharing for each current edge (u,v)
for (const SearchSpaceEdge ¤t_edge : forward_search_space)
{
const NodeID u = current_edge.first;
const NodeID v = current_edge.second;
if (nodes_in_path.find(v) != nodes_in_path.end())
{
// current_edge is on shortest path => sharing(v):=queue.GetKey(v);
approximated_forward_sharing.emplace(v, forward_heap1.GetKey(v));
}
else
{
// current edge is not on shortest path. Check if we know a value for the other
// endpoint
const auto sharing_of_u_iterator = approximated_forward_sharing.find(u);
if (sharing_of_u_iterator != approximated_forward_sharing.end())
{
approximated_forward_sharing.emplace(v, sharing_of_u_iterator->second);
}
}
}
// sweep over search space, compute backward sharing
for (const SearchSpaceEdge ¤t_edge : reverse_search_space)
{
const NodeID u = current_edge.first;
const NodeID v = current_edge.second;
if (nodes_in_path.find(v) != nodes_in_path.end())
{
// current_edge is on shortest path => sharing(u):=queue.GetKey(u);
approximated_reverse_sharing.emplace(v, reverse_heap1.GetKey(v));
}
else
{
// current edge is not on shortest path. Check if we know a value for the other
// endpoint
const auto sharing_of_u_iterator = approximated_reverse_sharing.find(u);
if (sharing_of_u_iterator != approximated_reverse_sharing.end())
{
approximated_reverse_sharing.emplace(v, sharing_of_u_iterator->second);
}
}
}
// util::SimpleLogger().Write(logDEBUG) << "fwd_search_space size: " <<
// forward_search_space.size() << ", marked " << approximated_forward_sharing.size() << "
// nodes";
// util::SimpleLogger().Write(logDEBUG) << "rev_search_space size: " <<
// reverse_search_space.size() << ", marked " << approximated_reverse_sharing.size() << "
// nodes";
std::vector<NodeID> preselected_node_list;
for (const NodeID node : via_node_candidate_list)
{
if (node == middle_node)
continue;
const auto fwd_iterator = approximated_forward_sharing.find(node);
const int fwd_sharing =
(fwd_iterator != approximated_forward_sharing.end()) ? fwd_iterator->second : 0;
const auto rev_iterator = approximated_reverse_sharing.find(node);
const int rev_sharing =
(rev_iterator != approximated_reverse_sharing.end()) ? rev_iterator->second : 0;
const int approximated_sharing = fwd_sharing + rev_sharing;
const int approximated_length = forward_heap1.GetKey(node) + reverse_heap1.GetKey(node);
const bool length_passes =
(approximated_length <
upper_bound_to_shortest_path_distance * (1 + VIAPATH_EPSILON));
const bool sharing_passes =
(approximated_sharing <= upper_bound_to_shortest_path_distance * VIAPATH_GAMMA);
const bool stretch_passes =
(approximated_length - approximated_sharing) <
((1. + VIAPATH_ALPHA) *
(upper_bound_to_shortest_path_distance - approximated_sharing));
if (length_passes && sharing_passes && stretch_passes)
{
preselected_node_list.emplace_back(node);
}
}
std::vector<NodeID> &packed_shortest_path = packed_forward_path;
if (!path_is_a_loop)
{
std::reverse(packed_shortest_path.begin(), packed_shortest_path.end());
packed_shortest_path.emplace_back(middle_node);
packed_shortest_path.insert(packed_shortest_path.end(), packed_reverse_path.begin(),
packed_reverse_path.end());
}
std::vector<RankedCandidateNode> ranked_candidates_list;
// prioritizing via nodes for deep inspection
for (const NodeID node : preselected_node_list)
{
int length_of_via_path = 0, sharing_of_via_path = 0;
ComputeLengthAndSharingOfViaPath(node, &length_of_via_path, &sharing_of_via_path,
packed_shortest_path, min_edge_offset);
const int maximum_allowed_sharing =
static_cast<int>(upper_bound_to_shortest_path_distance * VIAPATH_GAMMA);
if (sharing_of_via_path <= maximum_allowed_sharing &&
length_of_via_path <= upper_bound_to_shortest_path_distance * (1 + VIAPATH_EPSILON))
{
ranked_candidates_list.emplace_back(node, length_of_via_path, sharing_of_via_path);
}
}
std::sort(ranked_candidates_list.begin(), ranked_candidates_list.end());
NodeID selected_via_node = SPECIAL_NODEID;
int length_of_via_path = INVALID_EDGE_WEIGHT;
NodeID s_v_middle = SPECIAL_NODEID, v_t_middle = SPECIAL_NODEID;
for (const RankedCandidateNode &candidate : ranked_candidates_list)
{
if (ViaNodeCandidatePassesTTest(
forward_heap1, reverse_heap1, forward_heap2, reverse_heap2, candidate,
upper_bound_to_shortest_path_distance, &length_of_via_path, &s_v_middle,
&v_t_middle, min_edge_offset))
{
// select first admissable
selected_via_node = candidate.node;
break;
}
}
// Unpack shortest path and alternative, if they exist
if (INVALID_EDGE_WEIGHT != upper_bound_to_shortest_path_distance)
{
BOOST_ASSERT(!packed_shortest_path.empty());
raw_route_data.unpacked_path_segments.resize(1);
raw_route_data.source_traversed_in_reverse.push_back(
(packed_shortest_path.front() != phantom_node_pair.source_phantom.forward_node_id));
raw_route_data.target_traversed_in_reverse.push_back(
(packed_shortest_path.back() != phantom_node_pair.target_phantom.forward_node_id));
super::UnpackPath(
// -- packed input
packed_shortest_path.begin(), packed_shortest_path.end(),
// -- start of route
phantom_node_pair,
// -- unpacked output
raw_route_data.unpacked_path_segments.front());
raw_route_data.shortest_path_length = upper_bound_to_shortest_path_distance;
}
if (SPECIAL_NODEID != selected_via_node)
{
std::vector<NodeID> packed_alternate_path;
// retrieve alternate path
RetrievePackedAlternatePath(forward_heap1, reverse_heap1, forward_heap2, reverse_heap2,
s_v_middle, v_t_middle, packed_alternate_path);
raw_route_data.alt_source_traversed_in_reverse.push_back((
packed_alternate_path.front() != phantom_node_pair.source_phantom.forward_node_id));
raw_route_data.alt_target_traversed_in_reverse.push_back(
(packed_alternate_path.back() != phantom_node_pair.target_phantom.forward_node_id));
// unpack the alternate path
super::UnpackPath(packed_alternate_path.begin(), packed_alternate_path.end(),
phantom_node_pair, raw_route_data.unpacked_alternative);
raw_route_data.alternative_path_length = length_of_via_path;
}
else
{
BOOST_ASSERT(raw_route_data.alternative_path_length == INVALID_EDGE_WEIGHT);
}
}
private:
// unpack alternate <s,..,v,..,t> by exploring search spaces from v
void RetrievePackedAlternatePath(const QueryHeap &forward_heap1,
const QueryHeap &reverse_heap1,
const QueryHeap &forward_heap2,
const QueryHeap &reverse_heap2,
const NodeID s_v_middle,
const NodeID v_t_middle,
std::vector<NodeID> &packed_path) const
{
// fetch packed path [s,v)
std::vector<NodeID> packed_v_t_path;
super::RetrievePackedPathFromHeap(forward_heap1, reverse_heap2, s_v_middle, packed_path);
packed_path.pop_back(); // remove middle node. It's in both half-paths
// fetch patched path [v,t]
super::RetrievePackedPathFromHeap(forward_heap2, reverse_heap1, v_t_middle,
packed_v_t_path);
packed_path.insert(packed_path.end(), packed_v_t_path.begin(), packed_v_t_path.end());
}
// TODO: reorder parameters
// compute and unpack <s,..,v> and <v,..,t> by exploring search spaces
// from v and intersecting against queues. only half-searches have to be
// done at this stage
void ComputeLengthAndSharingOfViaPath(const NodeID via_node,
int *real_length_of_via_path,
int *sharing_of_via_path,
const std::vector<NodeID> &packed_shortest_path,
const EdgeWeight min_edge_offset)
{
engine_working_data.InitializeOrClearSecondThreadLocalStorage(
super::facade->GetNumberOfNodes());
QueryHeap &existing_forward_heap = *engine_working_data.forward_heap_1;
QueryHeap &existing_reverse_heap = *engine_working_data.reverse_heap_1;
QueryHeap &new_forward_heap = *engine_working_data.forward_heap_2;
QueryHeap &new_reverse_heap = *engine_working_data.reverse_heap_2;
std::vector<NodeID> packed_s_v_path;
std::vector<NodeID> packed_v_t_path;
std::vector<NodeID> partially_unpacked_shortest_path;
std::vector<NodeID> partially_unpacked_via_path;
NodeID s_v_middle = SPECIAL_NODEID;
int upper_bound_s_v_path_length = INVALID_EDGE_WEIGHT;
new_reverse_heap.Insert(via_node, 0, via_node);
// compute path <s,..,v> by reusing forward search from s
const bool constexpr STALLING_ENABLED = true;
const bool constexpr DO_NOT_FORCE_LOOPS = false;
while (!new_reverse_heap.Empty())
{
super::RoutingStep(new_reverse_heap, existing_forward_heap, s_v_middle,
upper_bound_s_v_path_length, min_edge_offset, false,
STALLING_ENABLED, DO_NOT_FORCE_LOOPS, DO_NOT_FORCE_LOOPS);
}
// compute path <v,..,t> by reusing backward search from node t
NodeID v_t_middle = SPECIAL_NODEID;
int upper_bound_of_v_t_path_length = INVALID_EDGE_WEIGHT;
new_forward_heap.Insert(via_node, 0, via_node);
while (!new_forward_heap.Empty())
{
super::RoutingStep(new_forward_heap, existing_reverse_heap, v_t_middle,
upper_bound_of_v_t_path_length, min_edge_offset, true,
STALLING_ENABLED, DO_NOT_FORCE_LOOPS, DO_NOT_FORCE_LOOPS);
}
*real_length_of_via_path = upper_bound_s_v_path_length + upper_bound_of_v_t_path_length;
if (SPECIAL_NODEID == s_v_middle || SPECIAL_NODEID == v_t_middle)
{
return;
}
// retrieve packed paths
super::RetrievePackedPathFromHeap(existing_forward_heap, new_reverse_heap, s_v_middle,
packed_s_v_path);
super::RetrievePackedPathFromHeap(new_forward_heap, existing_reverse_heap, v_t_middle,
packed_v_t_path);
// partial unpacking, compute sharing
// First partially unpack s-->v until paths deviate, note length of common path.
const int64_t s_v_min_path_size =
static_cast<int64_t>(std::min(packed_s_v_path.size(), packed_shortest_path.size())) - 1;
for (const int64_t current_node : util::irange<int64_t>(0, s_v_min_path_size))
{
if (packed_s_v_path[current_node] == packed_shortest_path[current_node] &&
packed_s_v_path[current_node + 1] == packed_shortest_path[current_node + 1])
{
EdgeID edgeID = facade->FindEdgeInEitherDirection(
packed_s_v_path[current_node], packed_s_v_path[current_node + 1]);
*sharing_of_via_path += facade->GetEdgeData(edgeID).distance;
}
else
{
if (packed_s_v_path[current_node] == packed_shortest_path[current_node])
{
super::UnpackEdge(packed_s_v_path[current_node],
packed_s_v_path[current_node + 1],
partially_unpacked_via_path);
super::UnpackEdge(packed_shortest_path[current_node],
packed_shortest_path[current_node + 1],
partially_unpacked_shortest_path);
break;
}
}
}
// traverse partially unpacked edge and note common prefix
const int64_t packed_path_length =
static_cast<int64_t>(std::min(partially_unpacked_via_path.size(),
partially_unpacked_shortest_path.size())) -
1;
for (int64_t current_node = 0; (current_node < packed_path_length) &&
(partially_unpacked_via_path[current_node] ==
partially_unpacked_shortest_path[current_node] &&
partially_unpacked_via_path[current_node + 1] ==
partially_unpacked_shortest_path[current_node + 1]);
++current_node)
{
EdgeID selected_edge =
facade->FindEdgeInEitherDirection(partially_unpacked_via_path[current_node],
partially_unpacked_via_path[current_node + 1]);
*sharing_of_via_path += facade->GetEdgeData(selected_edge).distance;
}
// Second, partially unpack v-->t in reverse order until paths deviate and note lengths
int64_t via_path_index = static_cast<int64_t>(packed_v_t_path.size()) - 1;
int64_t shortest_path_index = static_cast<int64_t>(packed_shortest_path.size()) - 1;
for (; via_path_index > 0 && shortest_path_index > 0;
--via_path_index, --shortest_path_index)
{
if (packed_v_t_path[via_path_index - 1] ==
packed_shortest_path[shortest_path_index - 1] &&
packed_v_t_path[via_path_index] == packed_shortest_path[shortest_path_index])
{
EdgeID edgeID = facade->FindEdgeInEitherDirection(
packed_v_t_path[via_path_index - 1], packed_v_t_path[via_path_index]);
*sharing_of_via_path += facade->GetEdgeData(edgeID).distance;
}
else
{
if (packed_v_t_path[via_path_index] == packed_shortest_path[shortest_path_index])
{
super::UnpackEdge(packed_v_t_path[via_path_index - 1],
packed_v_t_path[via_path_index], partially_unpacked_via_path);
super::UnpackEdge(packed_shortest_path[shortest_path_index - 1],
packed_shortest_path[shortest_path_index],
partially_unpacked_shortest_path);
break;
}
}
}
via_path_index = partially_unpacked_via_path.size() - 1;
shortest_path_index = partially_unpacked_shortest_path.size() - 1;
for (; via_path_index > 0 && shortest_path_index > 0;
--via_path_index, --shortest_path_index)
{
if (partially_unpacked_via_path[via_path_index - 1] ==
partially_unpacked_shortest_path[shortest_path_index - 1] &&
partially_unpacked_via_path[via_path_index] ==
partially_unpacked_shortest_path[shortest_path_index])
{
EdgeID edgeID = facade->FindEdgeInEitherDirection(
partially_unpacked_via_path[via_path_index - 1],
partially_unpacked_via_path[via_path_index]);
*sharing_of_via_path += facade->GetEdgeData(edgeID).distance;
}
else
{
break;
}
}
// finished partial unpacking spree! Amount of sharing is stored to appropriate pointer
// variable
}
// int approximateAmountOfSharing(
// const NodeID alternate_path_middle_node_id,
// QueryHeap & forward_heap,
// QueryHeap & reverse_heap,
// const std::vector<NodeID> & packed_shortest_path
// ) const {
// std::vector<NodeID> packed_alternate_path;
// super::RetrievePackedPathFromHeap(
// forward_heap,
// reverse_heap,
// alternate_path_middle_node_id,
// packed_alternate_path
// );
// if(packed_shortest_path.size() < 2 || packed_alternate_path.size() < 2) {
// return 0;
// }
// int sharing = 0;
// int aindex = 0;
// //compute forward sharing
// while( (packed_alternate_path[aindex] == packed_shortest_path[aindex]) &&
// (packed_alternate_path[aindex+1] == packed_shortest_path[aindex+1]) ) {
// // util::SimpleLogger().Write() << "retrieving edge (" <<
// packed_alternate_path[aindex] << "," << packed_alternate_path[aindex+1] << ")";
// EdgeID edgeID = facade->FindEdgeInEitherDirection(packed_alternate_path[aindex],
// packed_alternate_path[aindex+1]);
// sharing += facade->GetEdgeData(edgeID).distance;
// ++aindex;
// }
// aindex = packed_alternate_path.size()-1;
// int bindex = packed_shortest_path.size()-1;
// //compute backward sharing
// while( aindex > 0 && bindex > 0 && (packed_alternate_path[aindex] ==
// packed_shortest_path[bindex]) && (packed_alternate_path[aindex-1] ==
// packed_shortest_path[bindex-1]) ) {
// EdgeID edgeID = facade->FindEdgeInEitherDirection(packed_alternate_path[aindex],
// packed_alternate_path[aindex-1]);
// sharing += facade->GetEdgeData(edgeID).distance;
// --aindex; --bindex;
// }
// return sharing;
// }
// todo: reorder parameters
template <bool is_forward_directed>
void AlternativeRoutingStep(QueryHeap &heap1,
QueryHeap &heap2,
NodeID *middle_node,
int *upper_bound_to_shortest_path_distance,
std::vector<NodeID> &search_space_intersection,
std::vector<SearchSpaceEdge> &search_space,
const EdgeWeight min_edge_offset) const
{
QueryHeap &forward_heap = (is_forward_directed ? heap1 : heap2);
QueryHeap &reverse_heap = (is_forward_directed ? heap2 : heap1);
const NodeID node = forward_heap.DeleteMin();
const int distance = forward_heap.GetKey(node);
// const NodeID parentnode = forward_heap.GetData(node).parent;
// util::SimpleLogger().Write() << (is_forward_directed ? "[fwd] " : "[rev] ") << "settled
// edge ("
// << parentnode << "," << node << "), dist: " << distance;
const int scaled_distance =
static_cast<int>((distance + min_edge_offset) / (1. + VIAPATH_EPSILON));
if ((INVALID_EDGE_WEIGHT != *upper_bound_to_shortest_path_distance) &&
(scaled_distance > *upper_bound_to_shortest_path_distance))
{
forward_heap.DeleteAll();
return;
}
search_space.emplace_back(forward_heap.GetData(node).parent, node);
if (reverse_heap.WasInserted(node))
{
search_space_intersection.emplace_back(node);
const int new_distance = reverse_heap.GetKey(node) + distance;
if (new_distance < *upper_bound_to_shortest_path_distance)
{
if (new_distance >= 0)
{
*middle_node = node;
*upper_bound_to_shortest_path_distance = new_distance;
// util::SimpleLogger().Write() << "accepted middle_node " << *middle_node
// << " at
// distance " << new_distance;
// } else {
// util::SimpleLogger().Write() << "discarded middle_node " << *middle_node
// << "
// at distance " << new_distance;
}
else
{
// check whether there is a loop present at the node
const auto loop_distance = super::GetLoopWeight(node);
const int new_distance_with_loop = new_distance + loop_distance;
if (loop_distance != INVALID_EDGE_WEIGHT &&
new_distance_with_loop <= *upper_bound_to_shortest_path_distance)
{
*middle_node = node;
*upper_bound_to_shortest_path_distance = loop_distance;
}
}
}
}
for (auto edge : facade->GetAdjacentEdgeRange(node))
{
const EdgeData &data = facade->GetEdgeData(edge);
const bool edge_is_forward_directed =
(is_forward_directed ? data.forward : data.backward);
if (edge_is_forward_directed)
{
const NodeID to = facade->GetTarget(edge);
const int edge_weight = data.distance;
BOOST_ASSERT(edge_weight > 0);
const int to_distance = distance + edge_weight;
// New Node discovered -> Add to Heap + Node Info Storage
if (!forward_heap.WasInserted(to))
{
forward_heap.Insert(to, to_distance, node);
}
// Found a shorter Path -> Update distance
else if (to_distance < forward_heap.GetKey(to))
{
// new parent
forward_heap.GetData(to).parent = node;
// decreased distance
forward_heap.DecreaseKey(to, to_distance);
}
}
}
}
// conduct T-Test
bool ViaNodeCandidatePassesTTest(QueryHeap &existing_forward_heap,
QueryHeap &existing_reverse_heap,
QueryHeap &new_forward_heap,
QueryHeap &new_reverse_heap,
const RankedCandidateNode &candidate,
const int length_of_shortest_path,
int *length_of_via_path,
NodeID *s_v_middle,
NodeID *v_t_middle,
const EdgeWeight min_edge_offset) const
{
new_forward_heap.Clear();
new_reverse_heap.Clear();
std::vector<NodeID> packed_s_v_path;
std::vector<NodeID> packed_v_t_path;
*s_v_middle = SPECIAL_NODEID;
int upper_bound_s_v_path_length = INVALID_EDGE_WEIGHT;
// compute path <s,..,v> by reusing forward search from s
new_reverse_heap.Insert(candidate.node, 0, candidate.node);
const bool constexpr STALLING_ENABLED = true;
const bool constexpr DO_NOT_FORCE_LOOPS = false;
while (new_reverse_heap.Size() > 0)
{
super::RoutingStep(new_reverse_heap, existing_forward_heap, *s_v_middle,
upper_bound_s_v_path_length, min_edge_offset, false,
STALLING_ENABLED, DO_NOT_FORCE_LOOPS, DO_NOT_FORCE_LOOPS);
}
if (INVALID_EDGE_WEIGHT == upper_bound_s_v_path_length)
{
return false;
}
// compute path <v,..,t> by reusing backward search from t
*v_t_middle = SPECIAL_NODEID;
int upper_bound_of_v_t_path_length = INVALID_EDGE_WEIGHT;
new_forward_heap.Insert(candidate.node, 0, candidate.node);
while (new_forward_heap.Size() > 0)
{
super::RoutingStep(new_forward_heap, existing_reverse_heap, *v_t_middle,
upper_bound_of_v_t_path_length, min_edge_offset, true,
STALLING_ENABLED, DO_NOT_FORCE_LOOPS, DO_NOT_FORCE_LOOPS);
}
if (INVALID_EDGE_WEIGHT == upper_bound_of_v_t_path_length)
{
return false;
}
*length_of_via_path = upper_bound_s_v_path_length + upper_bound_of_v_t_path_length;
// retrieve packed paths
super::RetrievePackedPathFromHeap(existing_forward_heap, new_reverse_heap, *s_v_middle,
packed_s_v_path);
super::RetrievePackedPathFromHeap(new_forward_heap, existing_reverse_heap, *v_t_middle,
packed_v_t_path);
NodeID s_P = *s_v_middle, t_P = *v_t_middle;
if (SPECIAL_NODEID == s_P)
{
return false;
}
if (SPECIAL_NODEID == t_P)
{
return false;
}
const int T_threshold = static_cast<int>(VIAPATH_EPSILON * length_of_shortest_path);
int unpacked_until_distance = 0;
std::stack<SearchSpaceEdge> unpack_stack;
// Traverse path s-->v
for (std::size_t i = packed_s_v_path.size() - 1; (i > 0) && unpack_stack.empty(); --i)
{
const EdgeID current_edge_id =
facade->FindEdgeInEitherDirection(packed_s_v_path[i - 1], packed_s_v_path[i]);
const int length_of_current_edge = facade->GetEdgeData(current_edge_id).distance;
if ((length_of_current_edge + unpacked_until_distance) >= T_threshold)
{
unpack_stack.emplace(packed_s_v_path[i - 1], packed_s_v_path[i]);
}
else
{
unpacked_until_distance += length_of_current_edge;
s_P = packed_s_v_path[i - 1];
}
}
while (!unpack_stack.empty())
{
const SearchSpaceEdge via_path_edge = unpack_stack.top();
unpack_stack.pop();
EdgeID edge_in_via_path_id =
facade->FindEdgeInEitherDirection(via_path_edge.first, via_path_edge.second);
if (SPECIAL_EDGEID == edge_in_via_path_id)
{
return false;
}
const EdgeData ¤t_edge_data = facade->GetEdgeData(edge_in_via_path_id);
const bool current_edge_is_shortcut = current_edge_data.shortcut;
if (current_edge_is_shortcut)
{
const NodeID via_path_middle_node_id = current_edge_data.id;
const EdgeID second_segment_edge_id = facade->FindEdgeInEitherDirection(
via_path_middle_node_id, via_path_edge.second);
const int second_segment_length =
facade->GetEdgeData(second_segment_edge_id).distance;
// attention: !unpacking in reverse!
// Check if second segment is the one to go over treshold? if yes add second segment
// to stack, else push first segment to stack and add distance of second one.
if (unpacked_until_distance + second_segment_length >= T_threshold)
{
unpack_stack.emplace(via_path_middle_node_id, via_path_edge.second);
}
else
{
unpacked_until_distance += second_segment_length;
unpack_stack.emplace(via_path_edge.first, via_path_middle_node_id);
}
}
else
{
// edge is not a shortcut, set the start node for T-Test to end of edge.
unpacked_until_distance += current_edge_data.distance;
s_P = via_path_edge.first;
}
}
int t_test_path_length = unpacked_until_distance;
unpacked_until_distance = 0;
// Traverse path s-->v
BOOST_ASSERT(!packed_v_t_path.empty());
for (unsigned i = 0, packed_path_length = static_cast<unsigned>(packed_v_t_path.size() - 1);
(i < packed_path_length) && unpack_stack.empty(); ++i)
{
const EdgeID edgeID =
facade->FindEdgeInEitherDirection(packed_v_t_path[i], packed_v_t_path[i + 1]);
int length_of_current_edge = facade->GetEdgeData(edgeID).distance;
if (length_of_current_edge + unpacked_until_distance >= T_threshold)
{
unpack_stack.emplace(packed_v_t_path[i], packed_v_t_path[i + 1]);
}
else
{
unpacked_until_distance += length_of_current_edge;
t_P = packed_v_t_path[i + 1];
}
}
while (!unpack_stack.empty())
{
const SearchSpaceEdge via_path_edge = unpack_stack.top();
unpack_stack.pop();
EdgeID edge_in_via_path_id =
facade->FindEdgeInEitherDirection(via_path_edge.first, via_path_edge.second);
if (SPECIAL_EDGEID == edge_in_via_path_id)
{
return false;
}
const EdgeData ¤t_edge_data = facade->GetEdgeData(edge_in_via_path_id);
const bool IsViaEdgeShortCut = current_edge_data.shortcut;
if (IsViaEdgeShortCut)
{
const NodeID middleOfViaPath = current_edge_data.id;
EdgeID edgeIDOfFirstSegment =
facade->FindEdgeInEitherDirection(via_path_edge.first, middleOfViaPath);
int lengthOfFirstSegment = facade->GetEdgeData(edgeIDOfFirstSegment).distance;
// Check if first segment is the one to go over treshold? if yes first segment to
// stack, else push second segment to stack and add distance of first one.
if (unpacked_until_distance + lengthOfFirstSegment >= T_threshold)
{
unpack_stack.emplace(via_path_edge.first, middleOfViaPath);
}
else
{
unpacked_until_distance += lengthOfFirstSegment;
unpack_stack.emplace(middleOfViaPath, via_path_edge.second);
}
}
else
{
// edge is not a shortcut, set the start node for T-Test to end of edge.
unpacked_until_distance += current_edge_data.distance;
t_P = via_path_edge.second;
}
}
t_test_path_length += unpacked_until_distance;
// Run actual T-Test query and compare if distances equal.
engine_working_data.InitializeOrClearThirdThreadLocalStorage(
super::facade->GetNumberOfNodes());
QueryHeap &forward_heap3 = *engine_working_data.forward_heap_3;
QueryHeap &reverse_heap3 = *engine_working_data.reverse_heap_3;
int upper_bound = INVALID_EDGE_WEIGHT;
NodeID middle = SPECIAL_NODEID;
forward_heap3.Insert(s_P, 0, s_P);
reverse_heap3.Insert(t_P, 0, t_P);
// exploration from s and t until deletemin/(1+epsilon) > _lengt_oO_sShortest_path
while ((forward_heap3.Size() + reverse_heap3.Size()) > 0)
{
if (!forward_heap3.Empty())
{
super::RoutingStep(forward_heap3, reverse_heap3, middle, upper_bound,
min_edge_offset, true, STALLING_ENABLED, DO_NOT_FORCE_LOOPS,
DO_NOT_FORCE_LOOPS);
}
if (!reverse_heap3.Empty())
{
super::RoutingStep(reverse_heap3, forward_heap3, middle, upper_bound,
min_edge_offset, false, STALLING_ENABLED, DO_NOT_FORCE_LOOPS,
DO_NOT_FORCE_LOOPS);
}
}
return (upper_bound <= t_test_path_length);
}
};
}
}
}
#endif /* ALTERNATIVE_PATH_ROUTING_HPP */