osrm-backend/include/engine/routing_algorithms/routing_base_mld.hpp
Michael Bell 5d468f2897
Make edge metrics strongly typed (#6421)
This change takes the existing typedefs for weight, duration and
distance, and makes them proper types, using the existing Alias
functionality.

Primarily this is to prevent bugs where the metrics are switched,
but it also adds additional documentation. For example, it now
makes it clear (despite the naming of variables) that most of the
trip algorithm is running on the duration metric.

I've not made any changes to the casts performed between metrics
and numeric types, they now just more explicit.
2022-10-28 15:16:12 +01:00

664 lines
27 KiB
C++

#ifndef OSRM_ENGINE_ROUTING_BASE_MLD_HPP
#define OSRM_ENGINE_ROUTING_BASE_MLD_HPP
#include "engine/algorithm.hpp"
#include "engine/datafacade.hpp"
#include "engine/routing_algorithms/routing_base.hpp"
#include "engine/search_engine_data.hpp"
#include "util/typedefs.hpp"
#include <boost/assert.hpp>
#include <algorithm>
#include <iterator>
#include <limits>
#include <tuple>
#include <vector>
namespace osrm
{
namespace engine
{
namespace routing_algorithms
{
namespace mld
{
namespace
{
// Unrestricted search (Args is const PhantomNodes &):
// * use partition.GetQueryLevel to find the node query level based on source and target phantoms
// * allow to traverse all cells
template <typename MultiLevelPartition>
inline LevelID getNodeQueryLevel(const MultiLevelPartition &partition,
NodeID node,
const PhantomNode &source,
const PhantomNode &target)
{
auto level = [&partition, node](const SegmentID &source, const SegmentID &target) {
if (source.enabled && target.enabled)
return partition.GetQueryLevel(source.id, target.id, node);
return INVALID_LEVEL_ID;
};
return std::min(std::min(level(source.forward_segment_id, target.forward_segment_id),
level(source.forward_segment_id, target.reverse_segment_id)),
std::min(level(source.reverse_segment_id, target.forward_segment_id),
level(source.reverse_segment_id, target.reverse_segment_id)));
}
template <typename MultiLevelPartition>
inline LevelID getNodeQueryLevel(const MultiLevelPartition &partition,
NodeID node,
const PhantomEndpoints &endpoints)
{
return getNodeQueryLevel(partition, node, endpoints.source_phantom, endpoints.target_phantom);
}
template <typename MultiLevelPartition>
inline LevelID getNodeQueryLevel(const MultiLevelPartition &partition,
NodeID node,
const PhantomCandidatesToTarget &endpoint_candidates)
{
auto min_level = std::accumulate(
endpoint_candidates.source_phantoms.begin(),
endpoint_candidates.source_phantoms.end(),
INVALID_LEVEL_ID,
[&](LevelID current_level, const PhantomNode &source) {
return std::min(
current_level,
getNodeQueryLevel(partition, node, source, endpoint_candidates.target_phantom));
});
return min_level;
}
template <typename MultiLevelPartition>
inline LevelID getNodeQueryLevel(const MultiLevelPartition &partition,
NodeID node,
const PhantomEndpointCandidates &endpoint_candidates)
{
auto min_level = std::accumulate(
endpoint_candidates.source_phantoms.begin(),
endpoint_candidates.source_phantoms.end(),
INVALID_LEVEL_ID,
[&](LevelID level_1, const PhantomNode &source) {
return std::min(
level_1,
std::accumulate(endpoint_candidates.target_phantoms.begin(),
endpoint_candidates.target_phantoms.end(),
level_1,
[&](LevelID level_2, const PhantomNode &target) {
return std::min(
level_2,
getNodeQueryLevel(partition, node, source, target));
}));
});
return min_level;
}
template <typename PhantomCandidateT>
inline bool checkParentCellRestriction(CellID, const PhantomCandidateT &)
{
return true;
}
// Restricted search (Args is LevelID, CellID):
// * use the fixed level for queries
// * check if the node cell is the same as the specified parent
template <typename MultiLevelPartition>
inline LevelID getNodeQueryLevel(const MultiLevelPartition &, NodeID, LevelID level, CellID)
{
return level;
}
inline bool checkParentCellRestriction(CellID cell, LevelID, CellID parent)
{
return cell == parent;
}
// Unrestricted search with a single phantom node (Args is const PhantomNode &):
// * use partition.GetQueryLevel to find the node query level
// * allow to traverse all cells
template <typename MultiLevelPartition>
inline LevelID getNodeQueryLevel(const MultiLevelPartition &partition,
const NodeID node,
const PhantomNodeCandidates &candidates)
{
auto highest_different_level = [&partition, node](const SegmentID &segment) {
return segment.enabled ? partition.GetHighestDifferentLevel(segment.id, node)
: INVALID_LEVEL_ID;
};
auto node_level =
std::accumulate(candidates.begin(),
candidates.end(),
INVALID_LEVEL_ID,
[&](LevelID current_level, const PhantomNode &phantom_node) {
auto highest_level =
std::min(highest_different_level(phantom_node.forward_segment_id),
highest_different_level(phantom_node.reverse_segment_id));
return std::min(current_level, highest_level);
});
return node_level;
}
// Unrestricted search with a single phantom node and a vector of phantom nodes:
// * use partition.GetQueryLevel to find the node query level
// * allow to traverse all cells
template <typename MultiLevelPartition>
inline LevelID getNodeQueryLevel(const MultiLevelPartition &partition,
NodeID node,
const std::vector<PhantomNodeCandidates> &candidates_list,
const std::size_t phantom_index,
const std::vector<std::size_t> &phantom_indices)
{
// Get minimum level over all phantoms of the highest different level with respect to node
// This is equivalent to min_{∀ source, target} partition.GetQueryLevel(source, node, target)
auto init = getNodeQueryLevel(partition, node, candidates_list[phantom_index]);
auto result = std::accumulate(
phantom_indices.begin(), phantom_indices.end(), init, [&](LevelID level, size_t index) {
return std::min(level, getNodeQueryLevel(partition, node, candidates_list[index]));
});
return result;
}
} // namespace
// Heaps only record for each node its predecessor ("parent") on the shortest path.
// For re-constructing the actual path we need to trace back all parent "pointers".
// In contrast to the CH code MLD needs to know the edges (with clique arc property).
using PackedEdge = std::tuple</*from*/ NodeID, /*to*/ NodeID, /*from_clique_arc*/ bool>;
using PackedPath = std::vector<PackedEdge>;
template <bool DIRECTION, typename OutIter>
inline void retrievePackedPathFromSingleManyToManyHeap(
const SearchEngineData<Algorithm>::ManyToManyQueryHeap &heap, const NodeID middle, OutIter out)
{
NodeID current = middle;
NodeID parent = heap.GetData(current).parent;
while (current != parent)
{
const auto &data = heap.GetData(current);
if (DIRECTION == FORWARD_DIRECTION)
{
*out = std::make_tuple(parent, current, data.from_clique_arc);
++out;
}
else if (DIRECTION == REVERSE_DIRECTION)
{
*out = std::make_tuple(current, parent, data.from_clique_arc);
++out;
}
current = parent;
parent = heap.GetData(parent).parent;
}
}
template <bool DIRECTION>
inline PackedPath retrievePackedPathFromSingleManyToManyHeap(
const SearchEngineData<Algorithm>::ManyToManyQueryHeap &heap, const NodeID middle)
{
PackedPath packed_path;
retrievePackedPathFromSingleManyToManyHeap<DIRECTION>(
heap, middle, std::back_inserter(packed_path));
return packed_path;
}
template <bool DIRECTION, typename OutIter>
inline void retrievePackedPathFromSingleHeap(const SearchEngineData<Algorithm>::QueryHeap &heap,
const NodeID middle,
OutIter out)
{
NodeID current = middle;
NodeID parent = heap.GetData(current).parent;
while (current != parent)
{
const auto &data = heap.GetData(current);
if (DIRECTION == FORWARD_DIRECTION)
{
*out = std::make_tuple(parent, current, data.from_clique_arc);
++out;
}
else if (DIRECTION == REVERSE_DIRECTION)
{
*out = std::make_tuple(current, parent, data.from_clique_arc);
++out;
}
current = parent;
parent = heap.GetData(parent).parent;
}
}
template <bool DIRECTION>
inline PackedPath
retrievePackedPathFromSingleHeap(const SearchEngineData<Algorithm>::QueryHeap &heap,
const NodeID middle)
{
PackedPath packed_path;
retrievePackedPathFromSingleHeap<DIRECTION>(heap, middle, std::back_inserter(packed_path));
return packed_path;
}
// Trace path from middle to start in the forward search space (in reverse)
// and from middle to end in the reverse search space. Middle connects paths.
inline PackedPath
retrievePackedPathFromHeap(const SearchEngineData<Algorithm>::QueryHeap &forward_heap,
const SearchEngineData<Algorithm>::QueryHeap &reverse_heap,
const NodeID middle)
{
// Retrieve start -> middle. Is in reverse order since tracing back starts from middle.
auto packed_path = retrievePackedPathFromSingleHeap<FORWARD_DIRECTION>(forward_heap, middle);
std::reverse(begin(packed_path), end(packed_path));
// Retrieve middle -> end. Is already in correct order, tracing starts from middle.
auto into = std::back_inserter(packed_path);
retrievePackedPathFromSingleHeap<REVERSE_DIRECTION>(reverse_heap, middle, into);
return packed_path;
}
template <bool DIRECTION, typename Algorithm, typename... Args>
void relaxOutgoingEdges(const DataFacade<Algorithm> &facade,
typename SearchEngineData<Algorithm>::QueryHeap &forward_heap,
const typename SearchEngineData<Algorithm>::QueryHeap::HeapNode &heapNode,
const Args &... args)
{
const auto &partition = facade.GetMultiLevelPartition();
const auto &cells = facade.GetCellStorage();
const auto &metric = facade.GetCellMetric();
const auto level = getNodeQueryLevel(partition, heapNode.node, args...);
if (level >= 1 && !heapNode.data.from_clique_arc)
{
if (DIRECTION == FORWARD_DIRECTION)
{
// Shortcuts in forward direction
const auto &cell =
cells.GetCell(metric, level, partition.GetCell(level, heapNode.node));
auto destination = cell.GetDestinationNodes().begin();
for (auto shortcut_weight : cell.GetOutWeight(heapNode.node))
{
BOOST_ASSERT(destination != cell.GetDestinationNodes().end());
const NodeID to = *destination;
if (shortcut_weight != INVALID_EDGE_WEIGHT && heapNode.node != to)
{
const EdgeWeight to_weight = heapNode.weight + shortcut_weight;
BOOST_ASSERT(to_weight >= heapNode.weight);
const auto toHeapNode = forward_heap.GetHeapNodeIfWasInserted(to);
if (!toHeapNode)
{
forward_heap.Insert(to, to_weight, {heapNode.node, true});
}
else if (to_weight < toHeapNode->weight)
{
toHeapNode->data = {heapNode.node, true};
toHeapNode->weight = to_weight;
forward_heap.DecreaseKey(*toHeapNode);
}
}
++destination;
}
}
else
{
// Shortcuts in backward direction
const auto &cell =
cells.GetCell(metric, level, partition.GetCell(level, heapNode.node));
auto source = cell.GetSourceNodes().begin();
for (auto shortcut_weight : cell.GetInWeight(heapNode.node))
{
BOOST_ASSERT(source != cell.GetSourceNodes().end());
const NodeID to = *source;
if (shortcut_weight != INVALID_EDGE_WEIGHT && heapNode.node != to)
{
const EdgeWeight to_weight = heapNode.weight + shortcut_weight;
BOOST_ASSERT(to_weight >= heapNode.weight);
const auto toHeapNode = forward_heap.GetHeapNodeIfWasInserted(to);
if (!toHeapNode)
{
forward_heap.Insert(to, to_weight, {heapNode.node, true});
}
else if (to_weight < toHeapNode->weight)
{
toHeapNode->data = {heapNode.node, true};
toHeapNode->weight = to_weight;
forward_heap.DecreaseKey(*toHeapNode);
}
}
++source;
}
}
}
// Boundary edges
for (const auto edge : facade.GetBorderEdgeRange(level, heapNode.node))
{
const auto &edge_data = facade.GetEdgeData(edge);
if ((DIRECTION == FORWARD_DIRECTION) ? facade.IsForwardEdge(edge)
: facade.IsBackwardEdge(edge))
{
const NodeID to = facade.GetTarget(edge);
if (!facade.ExcludeNode(to) &&
checkParentCellRestriction(partition.GetCell(level + 1, to), args...))
{
const auto node_weight =
facade.GetNodeWeight(DIRECTION == FORWARD_DIRECTION ? heapNode.node : to);
const auto turn_penalty = facade.GetWeightPenaltyForEdgeID(edge_data.turn_id);
// TODO: BOOST_ASSERT(edge_data.weight == node_weight + turn_penalty);
const EdgeWeight to_weight =
heapNode.weight + node_weight + alias_cast<EdgeWeight>(turn_penalty);
const auto toHeapNode = forward_heap.GetHeapNodeIfWasInserted(to);
if (!toHeapNode)
{
forward_heap.Insert(to, to_weight, {heapNode.node, false});
}
else if (to_weight < toHeapNode->weight)
{
toHeapNode->data = {heapNode.node, false};
toHeapNode->weight = to_weight;
forward_heap.DecreaseKey(*toHeapNode);
}
}
}
}
}
template <bool DIRECTION, typename Algorithm, typename... Args>
void routingStep(const DataFacade<Algorithm> &facade,
typename SearchEngineData<Algorithm>::QueryHeap &forward_heap,
typename SearchEngineData<Algorithm>::QueryHeap &reverse_heap,
NodeID &middle_node,
EdgeWeight &path_upper_bound,
const std::vector<NodeID> &force_loop_forward_nodes,
const std::vector<NodeID> &force_loop_reverse_nodes,
const Args &... args)
{
const auto heapNode = forward_heap.DeleteMinGetHeapNode();
const auto weight = heapNode.weight;
BOOST_ASSERT(!facade.ExcludeNode(heapNode.node));
// Upper bound for the path source -> target with
// weight(source -> node) = weight weight(to -> target) ≤ reverse_weight
// is weight + reverse_weight
// More tighter upper bound requires additional condition reverse_heap.WasRemoved(to)
// with weight(to -> target) = reverse_weight and all weights ≥ 0
const auto reverseHeapNode = reverse_heap.GetHeapNodeIfWasInserted(heapNode.node);
if (reverseHeapNode)
{
auto reverse_weight = reverseHeapNode->weight;
auto path_weight = weight + reverse_weight;
// MLD uses loops forcing only to prune single node paths in forward and/or
// backward direction (there is no need to force loops in MLD but in CH)
if (!force_loop(force_loop_forward_nodes, heapNode) &&
!force_loop(force_loop_reverse_nodes, heapNode) && (path_weight >= EdgeWeight{0}) &&
(path_weight < path_upper_bound))
{
middle_node = heapNode.node;
path_upper_bound = path_weight;
}
}
// Relax outgoing edges from node
relaxOutgoingEdges<DIRECTION>(facade, forward_heap, heapNode, args...);
}
// With (s, middle, t) we trace back the paths middle -> s and middle -> t.
// This gives us a packed path (node ids) from the base graph around s and t,
// and overlay node ids otherwise. We then have to unpack the overlay clique
// edges by recursively descending unpacking the path down to the base graph.
using UnpackedNodes = std::vector<NodeID>;
using UnpackedEdges = std::vector<EdgeID>;
using UnpackedPath = std::tuple<EdgeWeight, UnpackedNodes, UnpackedEdges>;
template <typename Algorithm, typename... Args>
UnpackedPath search(SearchEngineData<Algorithm> &engine_working_data,
const DataFacade<Algorithm> &facade,
typename SearchEngineData<Algorithm>::QueryHeap &forward_heap,
typename SearchEngineData<Algorithm>::QueryHeap &reverse_heap,
const std::vector<NodeID> &force_loop_forward_nodes,
const std::vector<NodeID> &force_loop_reverse_nodes,
EdgeWeight weight_upper_bound,
const Args &... args)
{
if (forward_heap.Empty() || reverse_heap.Empty())
{
return std::make_tuple(INVALID_EDGE_WEIGHT, std::vector<NodeID>(), std::vector<EdgeID>());
}
const auto &partition = facade.GetMultiLevelPartition();
BOOST_ASSERT(!forward_heap.Empty() && forward_heap.MinKey() < INVALID_EDGE_WEIGHT);
BOOST_ASSERT(!reverse_heap.Empty() && reverse_heap.MinKey() < INVALID_EDGE_WEIGHT);
// run two-Target Dijkstra routing step.
NodeID middle = SPECIAL_NODEID;
EdgeWeight weight = weight_upper_bound;
EdgeWeight forward_heap_min = forward_heap.MinKey();
EdgeWeight reverse_heap_min = reverse_heap.MinKey();
while (forward_heap.Size() + reverse_heap.Size() > 0 &&
forward_heap_min + reverse_heap_min < weight)
{
if (!forward_heap.Empty())
{
routingStep<FORWARD_DIRECTION>(facade,
forward_heap,
reverse_heap,
middle,
weight,
force_loop_forward_nodes,
force_loop_reverse_nodes,
args...);
if (!forward_heap.Empty())
forward_heap_min = forward_heap.MinKey();
}
if (!reverse_heap.Empty())
{
routingStep<REVERSE_DIRECTION>(facade,
reverse_heap,
forward_heap,
middle,
weight,
force_loop_reverse_nodes,
force_loop_forward_nodes,
args...);
if (!reverse_heap.Empty())
reverse_heap_min = reverse_heap.MinKey();
}
};
// No path found for both target nodes?
if (weight >= weight_upper_bound || SPECIAL_NODEID == middle)
{
return std::make_tuple(INVALID_EDGE_WEIGHT, std::vector<NodeID>(), std::vector<EdgeID>());
}
// Get packed path as edges {from node ID, to node ID, from_clique_arc}
auto packed_path = retrievePackedPathFromHeap(forward_heap, reverse_heap, middle);
// Beware the edge case when start, middle, end are all the same.
// In this case we return a single node, no edges. We also don't unpack.
const NodeID source_node = !packed_path.empty() ? std::get<0>(packed_path.front()) : middle;
// Unpack path
std::vector<NodeID> unpacked_nodes;
std::vector<EdgeID> unpacked_edges;
unpacked_nodes.reserve(packed_path.size());
unpacked_edges.reserve(packed_path.size());
unpacked_nodes.push_back(source_node);
for (auto const &packed_edge : packed_path)
{
NodeID source, target;
bool overlay_edge;
std::tie(source, target, overlay_edge) = packed_edge;
if (!overlay_edge)
{ // a base graph edge
unpacked_nodes.push_back(target);
unpacked_edges.push_back(facade.FindEdge(source, target));
}
else
{ // an overlay graph edge
LevelID level = getNodeQueryLevel(partition, source, args...);
CellID parent_cell_id = partition.GetCell(level, source);
BOOST_ASSERT(parent_cell_id == partition.GetCell(level, target));
LevelID sublevel = level - 1;
// Here heaps can be reused, let's go deeper!
forward_heap.Clear();
reverse_heap.Clear();
forward_heap.Insert(source, {0}, {source});
reverse_heap.Insert(target, {0}, {target});
// TODO: when structured bindings will be allowed change to
// auto [subpath_weight, subpath_source, subpath_target, subpath] = ...
EdgeWeight subpath_weight;
std::vector<NodeID> subpath_nodes;
std::vector<EdgeID> subpath_edges;
std::tie(subpath_weight, subpath_nodes, subpath_edges) =
search(engine_working_data,
facade,
forward_heap,
reverse_heap,
force_loop_forward_nodes,
force_loop_reverse_nodes,
INVALID_EDGE_WEIGHT,
sublevel,
parent_cell_id);
BOOST_ASSERT(!subpath_edges.empty());
BOOST_ASSERT(subpath_nodes.size() > 1);
BOOST_ASSERT(subpath_nodes.front() == source);
BOOST_ASSERT(subpath_nodes.back() == target);
unpacked_nodes.insert(
unpacked_nodes.end(), std::next(subpath_nodes.begin()), subpath_nodes.end());
unpacked_edges.insert(unpacked_edges.end(), subpath_edges.begin(), subpath_edges.end());
}
}
return std::make_tuple(weight, std::move(unpacked_nodes), std::move(unpacked_edges));
}
// Alias to be compatible with the CH-based search
template <typename Algorithm, typename PhantomEndpointT>
inline void search(SearchEngineData<Algorithm> &engine_working_data,
const DataFacade<Algorithm> &facade,
typename SearchEngineData<Algorithm>::QueryHeap &forward_heap,
typename SearchEngineData<Algorithm>::QueryHeap &reverse_heap,
EdgeWeight &weight,
std::vector<NodeID> &unpacked_nodes,
const std::vector<NodeID> &force_loop_forward_node,
const std::vector<NodeID> &force_loop_reverse_node,
const PhantomEndpointT &endpoints,
const EdgeWeight weight_upper_bound = INVALID_EDGE_WEIGHT)
{
// TODO: change search calling interface to use unpacked_edges result
std::tie(weight, unpacked_nodes, std::ignore) = search(engine_working_data,
facade,
forward_heap,
reverse_heap,
force_loop_forward_node,
force_loop_reverse_node,
weight_upper_bound,
endpoints);
}
// TODO: refactor CH-related stub to use unpacked_edges
template <typename RandomIter, typename FacadeT>
void unpackPath(const FacadeT &facade,
RandomIter packed_path_begin,
RandomIter packed_path_end,
const PhantomEndpoints &route_endpoints,
std::vector<PathData> &unpacked_path)
{
const auto nodes_number = std::distance(packed_path_begin, packed_path_end);
BOOST_ASSERT(nodes_number > 0);
std::vector<NodeID> unpacked_nodes;
std::vector<EdgeID> unpacked_edges;
unpacked_nodes.reserve(nodes_number);
unpacked_edges.reserve(nodes_number);
unpacked_nodes.push_back(*packed_path_begin);
if (nodes_number > 1)
{
util::for_each_pair(
packed_path_begin,
packed_path_end,
[&facade, &unpacked_nodes, &unpacked_edges](const auto from, const auto to) {
unpacked_nodes.push_back(to);
unpacked_edges.push_back(facade.FindEdge(from, to));
});
}
annotatePath(facade, route_endpoints, unpacked_nodes, unpacked_edges, unpacked_path);
}
template <typename Algorithm>
double getNetworkDistance(SearchEngineData<Algorithm> &engine_working_data,
const DataFacade<Algorithm> &facade,
typename SearchEngineData<Algorithm>::QueryHeap &forward_heap,
typename SearchEngineData<Algorithm>::QueryHeap &reverse_heap,
const PhantomNode &source_phantom,
const PhantomNode &target_phantom,
EdgeWeight weight_upper_bound = INVALID_EDGE_WEIGHT)
{
forward_heap.Clear();
reverse_heap.Clear();
const PhantomEndpoints endpoints{source_phantom, target_phantom};
insertNodesInHeaps(forward_heap, reverse_heap, endpoints);
EdgeWeight weight = INVALID_EDGE_WEIGHT;
std::vector<NodeID> unpacked_nodes;
std::vector<EdgeID> unpacked_edges;
std::tie(weight, unpacked_nodes, unpacked_edges) = search(engine_working_data,
facade,
forward_heap,
reverse_heap,
{},
{},
weight_upper_bound,
endpoints);
if (weight == INVALID_EDGE_WEIGHT)
{
return std::numeric_limits<double>::max();
}
std::vector<PathData> unpacked_path;
annotatePath(facade, endpoints, unpacked_nodes, unpacked_edges, unpacked_path);
return getPathDistance(facade, unpacked_path, source_phantom, target_phantom);
}
} // namespace mld
} // namespace routing_algorithms
} // namespace engine
} // namespace osrm
#endif // OSRM_ENGINE_ROUTING_BASE_MLD_HPP