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osrm-backend/routing_algorithms/routing_base.hpp
Patrick Niklaus 019e26dd8e Refactor direct_shortest_path and shortest_path
2015-12-04 23:34:24 +01:00

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/*
Copyright (c) 2015, Project OSRM contributors
All rights reserved.
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this list
of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ROUTING_BASE_HPP
#define ROUTING_BASE_HPP
#include "../algorithms/coordinate_calculation.hpp"
#include "../data_structures/internal_route_result.hpp"
#include "../data_structures/search_engine_data.hpp"
#include "../data_structures/turn_instructions.hpp"
#include <boost/assert.hpp>
#include <stack>
SearchEngineData::SearchEngineHeapPtr SearchEngineData::forward_heap_1;
SearchEngineData::SearchEngineHeapPtr SearchEngineData::reverse_heap_1;
SearchEngineData::SearchEngineHeapPtr SearchEngineData::forward_heap_2;
SearchEngineData::SearchEngineHeapPtr SearchEngineData::reverse_heap_2;
SearchEngineData::SearchEngineHeapPtr SearchEngineData::forward_heap_3;
SearchEngineData::SearchEngineHeapPtr SearchEngineData::reverse_heap_3;
template <class DataFacadeT, class Derived> class BasicRoutingInterface
{
private:
using EdgeData = typename DataFacadeT::EdgeData;
protected:
DataFacadeT *facade;
public:
BasicRoutingInterface() = delete;
BasicRoutingInterface(const BasicRoutingInterface &) = delete;
explicit BasicRoutingInterface(DataFacadeT *facade) : facade(facade) {}
~BasicRoutingInterface() {}
// min_edge_offset is needed in case we use multiple
// nodes as start/target nodes with different (even negative) offsets.
// In that case the termination criterion is not correct
// anymore.
//
// Example:
// forward heap: a(-100), b(0),
// reverse heap: c(0), d(100)
//
// a --- d
// \ /
// / \
// b --- c
//
// This is equivalent to running a bi-directional Dijkstra on the following graph:
//
// a --- d
// / \ / \
// y x z
// \ / \ /
// b --- c
//
// The graph is constructed by inserting nodes y and z that are connected to the initial nodes
// using edges (y, a) with weight -100, (y, b) with weight 0 and,
// (d, z) with weight 100, (c, z) with weight 0 corresponding.
// Since we are dealing with a graph that contains _negative_ edges,
// we need to add an offset to the termination criterion.
void RoutingStep(SearchEngineData::QueryHeap &forward_heap,
SearchEngineData::QueryHeap &reverse_heap,
NodeID &middle_node_id,
int &upper_bound,
int min_edge_offset,
const bool forward_direction,
const bool stalling = true) const
{
const NodeID node = forward_heap.DeleteMin();
const int distance = forward_heap.GetKey(node);
if (reverse_heap.WasInserted(node))
{
const int new_distance = reverse_heap.GetKey(node) + distance;
if (new_distance < upper_bound)
{
if (new_distance >= 0)
{
middle_node_id = node;
upper_bound = new_distance;
}
}
}
// make sure we don't terminate too early if we initialize the distance
// for the nodes in the forward heap with the forward/reverse offset
BOOST_ASSERT(min_edge_offset <= 0);
if (distance + min_edge_offset > upper_bound)
{
forward_heap.DeleteAll();
return;
}
// Stalling
if (stalling)
{
for (const auto edge : facade->GetAdjacentEdgeRange(node))
{
const EdgeData &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 (forward_heap.WasInserted(to))
{
if (forward_heap.GetKey(to) + edge_weight < distance)
{
return;
}
}
}
}
}
for (const auto edge : facade->GetAdjacentEdgeRange(node))
{
const EdgeData &data = facade->GetEdgeData(edge);
bool forward_directionFlag = (forward_direction ? data.forward : data.backward);
if (forward_directionFlag)
{
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 (!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;
forward_heap.DecreaseKey(to, to_distance);
}
}
}
}
template <typename RandomIter>
void UnpackPath(RandomIter packed_path_begin,
RandomIter packed_path_end,
const PhantomNodes &phantom_node_pair,
std::vector<PathData> &unpacked_path) const
{
const bool start_traversed_in_reverse =
(*packed_path_begin != phantom_node_pair.source_phantom.forward_node_id);
const bool target_traversed_in_reverse =
(*std::prev(packed_path_end) != phantom_node_pair.target_phantom.forward_node_id);
const auto packed_path_size = std::distance(packed_path_begin, packed_path_end);
BOOST_ASSERT(packed_path_size > 0);
std::stack<std::pair<NodeID, NodeID>> recursion_stack;
// We have to push the path in reverse order onto the stack because it's LIFO.
for (auto current = std::prev(packed_path_end); current != packed_path_begin;
current = std::prev(current))
{
recursion_stack.emplace(*std::prev(current), *current);
}
std::pair<NodeID, NodeID> edge;
while (!recursion_stack.empty())
{
// edge.first edge.second
// *------------------>*
// edge_id
edge = recursion_stack.top();
recursion_stack.pop();
// facade->FindEdge does not suffice here in case of shortcuts.
// The above explanation unclear? Think!
EdgeID smaller_edge_id = SPECIAL_EDGEID;
int edge_weight = std::numeric_limits<EdgeWeight>::max();
for (const auto edge_id : facade->GetAdjacentEdgeRange(edge.first))
{
const int weight = facade->GetEdgeData(edge_id).distance;
if ((facade->GetTarget(edge_id) == edge.second) && (weight < edge_weight) &&
facade->GetEdgeData(edge_id).forward)
{
smaller_edge_id = edge_id;
edge_weight = weight;
}
}
// edge.first edge.second
// *<------------------*
// edge_id
if (SPECIAL_EDGEID == smaller_edge_id)
{
for (const auto edge_id : facade->GetAdjacentEdgeRange(edge.second))
{
const int weight = facade->GetEdgeData(edge_id).distance;
if ((facade->GetTarget(edge_id) == edge.first) && (weight < edge_weight) &&
facade->GetEdgeData(edge_id).backward)
{
smaller_edge_id = edge_id;
edge_weight = weight;
}
}
}
BOOST_ASSERT_MSG(edge_weight != INVALID_EDGE_WEIGHT, "edge id invalid");
const EdgeData &ed = facade->GetEdgeData(smaller_edge_id);
if (ed.shortcut)
{ // unpack
const NodeID middle_node_id = ed.id;
// again, we need to this in reversed order
recursion_stack.emplace(middle_node_id, edge.second);
recursion_stack.emplace(edge.first, middle_node_id);
}
else
{
BOOST_ASSERT_MSG(!ed.shortcut, "original edge flagged as shortcut");
unsigned name_index = facade->GetNameIndexFromEdgeID(ed.id);
const TurnInstruction turn_instruction = facade->GetTurnInstructionForEdgeID(ed.id);
const TravelMode travel_mode = facade->GetTravelModeForEdgeID(ed.id);
if (!facade->EdgeIsCompressed(ed.id))
{
BOOST_ASSERT(!facade->EdgeIsCompressed(ed.id));
unpacked_path.emplace_back(facade->GetGeometryIndexForEdgeID(ed.id), name_index,
turn_instruction, ed.distance, travel_mode);
}
else
{
std::vector<unsigned> id_vector;
facade->GetUncompressedGeometry(facade->GetGeometryIndexForEdgeID(ed.id),
id_vector);
const std::size_t start_index =
(unpacked_path.empty()
? ((start_traversed_in_reverse)
? id_vector.size() -
phantom_node_pair.source_phantom.fwd_segment_position - 1
: phantom_node_pair.source_phantom.fwd_segment_position)
: 0);
const std::size_t end_index = id_vector.size();
BOOST_ASSERT(start_index >= 0);
BOOST_ASSERT(start_index <= end_index);
for (std::size_t i = start_index; i < end_index; ++i)
{
unpacked_path.emplace_back(id_vector[i], name_index,
TurnInstruction::NoTurn, 0, travel_mode);
}
unpacked_path.back().turn_instruction = turn_instruction;
unpacked_path.back().segment_duration = ed.distance;
}
}
}
if (SPECIAL_EDGEID != phantom_node_pair.target_phantom.packed_geometry_id)
{
std::vector<unsigned> id_vector;
facade->GetUncompressedGeometry(phantom_node_pair.target_phantom.packed_geometry_id,
id_vector);
const bool is_local_path = (phantom_node_pair.source_phantom.packed_geometry_id ==
phantom_node_pair.target_phantom.packed_geometry_id) &&
unpacked_path.empty();
std::size_t start_index = 0;
if (is_local_path)
{
start_index = phantom_node_pair.source_phantom.fwd_segment_position;
if (target_traversed_in_reverse)
{
start_index =
id_vector.size() - phantom_node_pair.source_phantom.fwd_segment_position;
}
}
std::size_t end_index = phantom_node_pair.target_phantom.fwd_segment_position;
if (target_traversed_in_reverse)
{
std::reverse(id_vector.begin(), id_vector.end());
end_index =
id_vector.size() - phantom_node_pair.target_phantom.fwd_segment_position;
}
if (start_index > end_index)
{
start_index = std::min(start_index, id_vector.size() - 1);
}
for (std::size_t i = start_index; i != end_index; (start_index < end_index ? ++i : --i))
{
BOOST_ASSERT(i < id_vector.size());
BOOST_ASSERT(phantom_node_pair.target_phantom.forward_travel_mode > 0);
unpacked_path.emplace_back(PathData{
id_vector[i], phantom_node_pair.target_phantom.name_id, TurnInstruction::NoTurn,
0, phantom_node_pair.target_phantom.forward_travel_mode});
}
}
// there is no equivalent to a node-based node in an edge-expanded graph.
// two equivalent routes may start (or end) at different node-based edges
// as they are added with the offset how much "distance" on the edge
// has already been traversed. Depending on offset one needs to remove
// the last node.
if (unpacked_path.size() > 1)
{
const std::size_t last_index = unpacked_path.size() - 1;
const std::size_t second_to_last_index = last_index - 1;
// looks like a trivially true check but tests for underflow
BOOST_ASSERT(last_index > second_to_last_index);
if (unpacked_path[last_index].node == unpacked_path[second_to_last_index].node)
{
unpacked_path.pop_back();
}
BOOST_ASSERT(!unpacked_path.empty());
}
}
void UnpackEdge(const NodeID s, const NodeID t, std::vector<NodeID> &unpacked_path) const
{
std::stack<std::pair<NodeID, NodeID>> recursion_stack;
recursion_stack.emplace(s, t);
std::pair<NodeID, NodeID> edge;
while (!recursion_stack.empty())
{
edge = recursion_stack.top();
recursion_stack.pop();
EdgeID smaller_edge_id = SPECIAL_EDGEID;
int edge_weight = std::numeric_limits<EdgeWeight>::max();
for (const auto edge_id : facade->GetAdjacentEdgeRange(edge.first))
{
const int weight = facade->GetEdgeData(edge_id).distance;
if ((facade->GetTarget(edge_id) == edge.second) && (weight < edge_weight) &&
facade->GetEdgeData(edge_id).forward)
{
smaller_edge_id = edge_id;
edge_weight = weight;
}
}
if (SPECIAL_EDGEID == smaller_edge_id)
{
for (const auto edge_id : facade->GetAdjacentEdgeRange(edge.second))
{
const int weight = facade->GetEdgeData(edge_id).distance;
if ((facade->GetTarget(edge_id) == edge.first) && (weight < edge_weight) &&
facade->GetEdgeData(edge_id).backward)
{
smaller_edge_id = edge_id;
edge_weight = weight;
}
}
}
BOOST_ASSERT_MSG(edge_weight != std::numeric_limits<EdgeWeight>::max(),
"edge weight invalid");
const EdgeData &ed = facade->GetEdgeData(smaller_edge_id);
if (ed.shortcut)
{ // unpack
const NodeID middle_node_id = ed.id;
// again, we need to this in reversed order
recursion_stack.emplace(middle_node_id, edge.second);
recursion_stack.emplace(edge.first, middle_node_id);
}
else
{
BOOST_ASSERT_MSG(!ed.shortcut, "edge must be shortcut");
unpacked_path.emplace_back(edge.first);
}
}
unpacked_path.emplace_back(t);
}
void RetrievePackedPathFromHeap(const SearchEngineData::QueryHeap &forward_heap,
const SearchEngineData::QueryHeap &reverse_heap,
const NodeID middle_node_id,
std::vector<NodeID> &packed_path) const
{
RetrievePackedPathFromSingleHeap(forward_heap, middle_node_id, packed_path);
std::reverse(packed_path.begin(), packed_path.end());
packed_path.emplace_back(middle_node_id);
RetrievePackedPathFromSingleHeap(reverse_heap, middle_node_id, packed_path);
}
void RetrievePackedPathFromSingleHeap(const SearchEngineData::QueryHeap &search_heap,
const NodeID middle_node_id,
std::vector<NodeID> &packed_path) const
{
NodeID current_node_id = middle_node_id;
while (current_node_id != search_heap.GetData(current_node_id).parent)
{
current_node_id = search_heap.GetData(current_node_id).parent;
packed_path.emplace_back(current_node_id);
}
}
// assumes that heaps are already setup correctly.
void Search(SearchEngineData::QueryHeap &forward_heap,
SearchEngineData::QueryHeap &reverse_heap,
int &distance,
std::vector<NodeID> &packed_leg) const
{
NodeID middle = SPECIAL_NODEID;
// get offset to account for offsets on phantom nodes on compressed edges
const auto min_edge_offset = std::min(0, forward_heap.MinKey());
BOOST_ASSERT(min_edge_offset <= 0);
// we only every insert negative offsets for nodes in the forward heap
BOOST_ASSERT(reverse_heap.MinKey() >= 0);
// run two-Target Dijkstra routing step.
while (0 < (forward_heap.Size() + reverse_heap.Size()))
{
if (!forward_heap.Empty())
{
RoutingStep(forward_heap, reverse_heap, middle, distance, min_edge_offset, true);
}
if (!reverse_heap.Empty())
{
RoutingStep(reverse_heap, forward_heap, middle, distance, min_edge_offset, false);
}
}
// No path found for both target nodes?
if (INVALID_EDGE_WEIGHT == distance || SPECIAL_NODEID == middle)
{
return;
}
// Was a paths over one of the forward/reverse nodes not found?
BOOST_ASSERT_MSG((SPECIAL_NODEID != middle && INVALID_EDGE_WEIGHT != distance),
"no path found");
RetrievePackedPathFromHeap(forward_heap, reverse_heap, middle, packed_leg);
}
// assumes that heaps are already setup correctly.
void SearchWithCore(SearchEngineData::QueryHeap &forward_heap,
SearchEngineData::QueryHeap &reverse_heap,
SearchEngineData::QueryHeap &forward_core_heap,
SearchEngineData::QueryHeap &reverse_core_heap,
int &distance,
std::vector<NodeID> &packed_leg) const
{
NodeID middle = SPECIAL_NODEID;
std::vector<std::pair<NodeID, EdgeWeight>> forward_entry_points;
std::vector<std::pair<NodeID, EdgeWeight>> reverse_entry_points;
// get offset to account for offsets on phantom nodes on compressed edges
const auto min_edge_offset = std::min(0, forward_heap.MinKey());
// we only every insert negative offsets for nodes in the forward heap
BOOST_ASSERT(reverse_heap.MinKey() >= 0);
// run two-Target Dijkstra routing step.
while (0 < (forward_heap.Size() + reverse_heap.Size()))
{
if (!forward_heap.Empty())
{
if (facade->IsCoreNode(forward_heap.Min()))
{
const NodeID node = forward_heap.DeleteMin();
const int key = forward_heap.GetKey(node);
forward_entry_points.emplace_back(node, key);
}
else
{
RoutingStep(forward_heap, reverse_heap, middle, distance, min_edge_offset,
true);
}
}
if (!reverse_heap.Empty())
{
if (facade->IsCoreNode(reverse_heap.Min()))
{
const NodeID node = reverse_heap.DeleteMin();
const int key = reverse_heap.GetKey(node);
reverse_entry_points.emplace_back(node, key);
}
else
{
RoutingStep(reverse_heap, forward_heap, middle, distance, min_edge_offset,
false);
}
}
}
// TODO check if unordered_set might be faster
// sort by id and increasing by distance
auto entry_point_comparator = [](const std::pair<NodeID, EdgeWeight> &lhs,
const std::pair<NodeID, EdgeWeight> &rhs)
{
return lhs.first < rhs.first || (lhs.first == rhs.first && lhs.second < rhs.second);
};
std::sort(forward_entry_points.begin(), forward_entry_points.end(), entry_point_comparator);
std::sort(reverse_entry_points.begin(), reverse_entry_points.end(), entry_point_comparator);
NodeID last_id = SPECIAL_NODEID;
for (const auto p : forward_entry_points)
{
if (p.first == last_id)
{
continue;
}
forward_core_heap.Insert(p.first, p.second, p.first);
last_id = p.first;
}
last_id = SPECIAL_NODEID;
for (const auto p : reverse_entry_points)
{
if (p.first == last_id)
{
continue;
}
reverse_core_heap.Insert(p.first, p.second, p.first);
last_id = p.first;
}
// get offset to account for offsets on phantom nodes on compressed edges
int min_core_edge_offset = 0;
if (forward_core_heap.Size() > 0)
{
min_core_edge_offset = std::min(min_core_edge_offset, forward_core_heap.MinKey());
}
if (reverse_core_heap.Size() > 0 && reverse_core_heap.MinKey() < 0)
{
min_core_edge_offset = std::min(min_core_edge_offset, reverse_core_heap.MinKey());
}
BOOST_ASSERT(min_core_edge_offset <= 0);
// run two-target Dijkstra routing step on core with termination criterion
while (0 < (forward_core_heap.Size() + reverse_core_heap.Size()) &&
distance > (forward_core_heap.MinKey() + reverse_core_heap.MinKey()))
{
if (!forward_core_heap.Empty())
{
RoutingStep(forward_core_heap, reverse_core_heap, middle, distance,
min_core_edge_offset, true, false);
}
if (!reverse_core_heap.Empty())
{
RoutingStep(reverse_core_heap, forward_core_heap, middle, distance,
min_core_edge_offset, false, false);
}
}
// No path found for both target nodes?
if (INVALID_EDGE_WEIGHT == distance || SPECIAL_NODEID == middle)
{
return;
}
// Was a paths over one of the forward/reverse nodes not found?
BOOST_ASSERT_MSG((SPECIAL_NODEID != middle && INVALID_EDGE_WEIGHT != distance),
"no path found");
// we need to unpack sub path from core heaps
if (facade->IsCoreNode(middle))
{
std::vector<NodeID> packed_core_leg;
RetrievePackedPathFromHeap(forward_core_heap, reverse_core_heap, middle,
packed_core_leg);
BOOST_ASSERT(packed_core_leg.size() > 0);
RetrievePackedPathFromSingleHeap(forward_heap, packed_core_leg.front(), packed_leg);
std::reverse(packed_leg.begin(), packed_leg.end());
packed_leg.insert(packed_leg.end(), packed_core_leg.begin(), packed_core_leg.end());
RetrievePackedPathFromSingleHeap(reverse_heap, packed_core_leg.back(), packed_leg);
}
else
{
RetrievePackedPathFromHeap(forward_heap, reverse_heap, middle, packed_leg);
}
}
double get_network_distance(SearchEngineData::QueryHeap &forward_heap,
SearchEngineData::QueryHeap &reverse_heap,
const PhantomNode &source_phantom,
const PhantomNode &target_phantom) const
{
EdgeWeight upper_bound = INVALID_EDGE_WEIGHT;
NodeID middle_node = SPECIAL_NODEID;
EdgeWeight edge_offset = std::min(0, -source_phantom.GetForwardWeightPlusOffset());
edge_offset = std::min(edge_offset, -source_phantom.GetReverseWeightPlusOffset());
if (source_phantom.forward_node_id != SPECIAL_NODEID)
{
forward_heap.Insert(source_phantom.forward_node_id,
-source_phantom.GetForwardWeightPlusOffset(),
source_phantom.forward_node_id);
}
if (source_phantom.reverse_node_id != SPECIAL_NODEID)
{
forward_heap.Insert(source_phantom.reverse_node_id,
-source_phantom.GetReverseWeightPlusOffset(),
source_phantom.reverse_node_id);
}
if (target_phantom.forward_node_id != SPECIAL_NODEID)
{
reverse_heap.Insert(target_phantom.forward_node_id,
target_phantom.GetForwardWeightPlusOffset(),
target_phantom.forward_node_id);
}
if (target_phantom.reverse_node_id != SPECIAL_NODEID)
{
reverse_heap.Insert(target_phantom.reverse_node_id,
target_phantom.GetReverseWeightPlusOffset(),
target_phantom.reverse_node_id);
}
// search from s and t till new_min/(1+epsilon) > length_of_shortest_path
while (0 < (forward_heap.Size() + reverse_heap.Size()))
{
if (0 < forward_heap.Size())
{
RoutingStep(forward_heap, reverse_heap, middle_node, upper_bound, edge_offset,
true);
}
if (0 < reverse_heap.Size())
{
RoutingStep(reverse_heap, forward_heap, middle_node, upper_bound, edge_offset,
false);
}
}
double distance = std::numeric_limits<double>::max();
if (upper_bound != INVALID_EDGE_WEIGHT)
{
std::vector<NodeID> packed_leg;
RetrievePackedPathFromHeap(forward_heap, reverse_heap, middle_node, packed_leg);
std::vector<PathData> unpacked_path;
PhantomNodes nodes;
nodes.source_phantom = source_phantom;
nodes.target_phantom = target_phantom;
UnpackPath(packed_leg.begin(), packed_leg.end(), nodes, unpacked_path);
FixedPointCoordinate previous_coordinate = source_phantom.location;
FixedPointCoordinate current_coordinate;
distance = 0;
for (const auto &p : unpacked_path)
{
current_coordinate = facade->GetCoordinateOfNode(p.node);
distance += coordinate_calculation::haversine_distance(previous_coordinate,
current_coordinate);
previous_coordinate = current_coordinate;
}
distance += coordinate_calculation::haversine_distance(previous_coordinate,
target_phantom.location);
}
return distance;
}
};
#endif // ROUTING_BASE_HPP
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