289 lines
11 KiB
C++
289 lines
11 KiB
C++
#ifndef OSRM_ENGINE_ROUTING_BASE_MLD_HPP
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#define OSRM_ENGINE_ROUTING_BASE_MLD_HPP
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#include "engine/algorithm.hpp"
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#include "engine/datafacade/contiguous_internalmem_datafacade.hpp"
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#include "engine/routing_algorithms/routing_base.hpp"
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#include "engine/search_engine_data.hpp"
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#include "util/typedefs.hpp"
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#include <boost/assert.hpp>
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namespace osrm
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{
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namespace engine
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{
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namespace routing_algorithms
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{
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namespace mld
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{
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namespace
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{
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// Unrestricted search (Args is const PhantomNodes &):
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// * use partition.GetQueryLevel to find the node query level based on source and target phantoms
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// * allow to traverse all cells
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LevelID getNodeQureyLevel(const partition::MultiLevelPartitionView &partition,
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NodeID node,
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const PhantomNodes &phantom_nodes)
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{
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auto level = [&partition, node](const SegmentID &source, const SegmentID &target) {
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if (source.enabled && target.enabled)
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return partition.GetQueryLevel(source.id, target.id, node);
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return INVALID_LEVEL_ID;
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};
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return std::min(std::min(level(phantom_nodes.source_phantom.forward_segment_id,
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phantom_nodes.target_phantom.forward_segment_id),
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level(phantom_nodes.source_phantom.forward_segment_id,
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phantom_nodes.target_phantom.reverse_segment_id)),
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std::min(level(phantom_nodes.source_phantom.reverse_segment_id,
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phantom_nodes.target_phantom.forward_segment_id),
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level(phantom_nodes.source_phantom.reverse_segment_id,
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phantom_nodes.target_phantom.reverse_segment_id)));
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}
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bool checkParentCellRestriction(CellID, const PhantomNodes &) { return true; }
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// Restricted search (Args is LevelID, CellID):
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// * use the fixed level for queries
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// * check if the node cell is the same as the specified parent onr
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LevelID getNodeQureyLevel(const partition::MultiLevelPartitionView &, NodeID, LevelID level, CellID)
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{
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return level;
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}
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bool checkParentCellRestriction(CellID cell, LevelID, CellID parent) { return cell == parent; }
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}
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template <bool DIRECTION, typename... Args>
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void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm::MLD> &facade,
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SearchEngineData::MultiLayerDijkstraHeap &forward_heap,
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SearchEngineData::MultiLayerDijkstraHeap &reverse_heap,
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NodeID &middle_node,
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EdgeWeight &path_upper_bound,
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Args... args)
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{
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const auto &partition = facade.GetMultiLevelPartition();
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const auto &cells = facade.GetCellStorage();
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const auto node = forward_heap.DeleteMin();
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const auto weight = forward_heap.GetKey(node);
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// Upper bound for the path source -> target with
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// weight(source -> node) = weight weight(to -> target) ≤ reverse_weight
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// is weight + reverse_weight
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// More tighter upper bound requires additional condition reverse_heap.WasRemoved(to)
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// with weight(to -> target) = reverse_weight and all weights ≥ 0
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if (reverse_heap.WasInserted(node))
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{
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auto reverse_weight = reverse_heap.GetKey(node);
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auto path_weight = weight + reverse_weight;
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if (path_weight >= 0 && path_weight < path_upper_bound)
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{
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middle_node = node;
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path_upper_bound = path_weight;
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}
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}
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const auto level = getNodeQureyLevel(partition, node, args...);
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if (level >= 1 && !forward_heap.GetData(node).from_clique_arc)
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{
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if (DIRECTION == FORWARD_DIRECTION)
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{
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// Shortcuts in forward direction
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const auto &cell = cells.GetCell(level, partition.GetCell(level, node));
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auto destination = cell.GetDestinationNodes().begin();
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for (auto shortcut_weight : cell.GetOutWeight(node))
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{
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BOOST_ASSERT(destination != cell.GetDestinationNodes().end());
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const NodeID to = *destination;
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if (shortcut_weight != INVALID_EDGE_WEIGHT && node != to)
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{
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const EdgeWeight to_weight = weight + shortcut_weight;
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if (!forward_heap.WasInserted(to))
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{
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forward_heap.Insert(to, to_weight, {node, true});
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}
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else if (to_weight < forward_heap.GetKey(to))
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{
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forward_heap.GetData(to) = {node, true};
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forward_heap.DecreaseKey(to, to_weight);
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}
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}
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++destination;
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}
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}
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else
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{
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// Shortcuts in backward direction
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const auto &cell = cells.GetCell(level, partition.GetCell(level, node));
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auto source = cell.GetSourceNodes().begin();
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for (auto shortcut_weight : cell.GetInWeight(node))
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{
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BOOST_ASSERT(source != cell.GetSourceNodes().end());
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const NodeID to = *source;
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if (shortcut_weight != INVALID_EDGE_WEIGHT && node != to)
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{
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const EdgeWeight to_weight = weight + shortcut_weight;
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if (!forward_heap.WasInserted(to))
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{
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forward_heap.Insert(to, to_weight, {node, true});
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}
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else if (to_weight < forward_heap.GetKey(to))
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{
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forward_heap.GetData(to) = {node, true};
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forward_heap.DecreaseKey(to, to_weight);
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}
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}
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++source;
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}
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}
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}
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// Boundary edges
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for (const auto edge : facade.GetAdjacentEdgeRange(node))
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{
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const auto &edge_data = facade.GetEdgeData(edge);
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if (DIRECTION == FORWARD_DIRECTION ? edge_data.forward : edge_data.backward)
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{
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const NodeID to = facade.GetTarget(edge);
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if (checkParentCellRestriction(partition.GetCell(level + 1, to), args...) &&
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partition.GetHighestDifferentLevel(node, to) >= level)
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{
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BOOST_ASSERT_MSG(edge_data.weight > 0, "edge_weight invalid");
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const EdgeWeight to_weight = weight + edge_data.weight;
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if (!forward_heap.WasInserted(to))
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{
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forward_heap.Insert(to, to_weight, {node, false});
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}
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else if (to_weight < forward_heap.GetKey(to))
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{
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forward_heap.GetData(to) = {node, false};
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forward_heap.DecreaseKey(to, to_weight);
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}
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}
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}
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}
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}
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template <typename... Args>
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std::tuple<EdgeWeight, NodeID, NodeID, std::vector<EdgeID>>
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search(const datafacade::ContiguousInternalMemoryDataFacade<algorithm::MLD> &facade,
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SearchEngineData::MultiLayerDijkstraHeap &forward_heap,
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SearchEngineData::MultiLayerDijkstraHeap &reverse_heap,
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Args... args)
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{
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const auto &partition = facade.GetMultiLevelPartition();
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BOOST_ASSERT(!forward_heap.Empty() && forward_heap.MinKey() < INVALID_EDGE_WEIGHT);
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BOOST_ASSERT(!reverse_heap.Empty() && reverse_heap.MinKey() < INVALID_EDGE_WEIGHT);
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// run two-Target Dijkstra routing step.
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NodeID middle = SPECIAL_NODEID;
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EdgeWeight weight = INVALID_EDGE_WEIGHT;
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EdgeWeight forward_heap_min = forward_heap.MinKey();
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EdgeWeight reverse_heap_min = reverse_heap.MinKey();
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while (forward_heap.Size() + reverse_heap.Size() > 0 &&
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forward_heap_min + reverse_heap_min < weight)
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{
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if (!forward_heap.Empty())
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{
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routingStep<FORWARD_DIRECTION>(
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facade, forward_heap, reverse_heap, middle, weight, args...);
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if (!forward_heap.Empty())
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forward_heap_min = forward_heap.MinKey();
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}
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if (!reverse_heap.Empty())
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{
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routingStep<REVERSE_DIRECTION>(
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facade, reverse_heap, forward_heap, middle, weight, args...);
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if (!reverse_heap.Empty())
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reverse_heap_min = reverse_heap.MinKey();
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}
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};
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// No path found for both target nodes?
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if (weight == INVALID_EDGE_WEIGHT || SPECIAL_NODEID == middle)
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{
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return std::make_tuple(
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INVALID_EDGE_WEIGHT, SPECIAL_NODEID, SPECIAL_NODEID, std::vector<EdgeID>());
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}
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// Get packed path as edges {from node ID, to node ID, edge ID}
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std::vector<std::tuple<NodeID, NodeID, bool>> packed_path;
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NodeID current_node = middle, parent_node = forward_heap.GetData(middle).parent;
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while (parent_node != current_node)
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{
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const auto &data = forward_heap.GetData(current_node);
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packed_path.push_back(std::make_tuple(parent_node, current_node, data.from_clique_arc));
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current_node = parent_node;
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parent_node = forward_heap.GetData(parent_node).parent;
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}
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std::reverse(std::begin(packed_path), std::end(packed_path));
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const NodeID source_node = current_node;
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current_node = middle, parent_node = reverse_heap.GetData(middle).parent;
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while (parent_node != current_node)
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{
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const auto &data = reverse_heap.GetData(current_node);
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packed_path.push_back(std::make_tuple(current_node, parent_node, data.from_clique_arc));
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current_node = parent_node;
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parent_node = reverse_heap.GetData(parent_node).parent;
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}
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const NodeID target_node = current_node;
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// Unpack path
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std::vector<EdgeID> unpacked_path;
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unpacked_path.reserve(packed_path.size());
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for (auto const &packed_edge : packed_path)
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{
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NodeID source, target;
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bool overlay_edge;
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std::tie(source, target, overlay_edge) = packed_edge;
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if (!overlay_edge)
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{ // a base graph edge
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unpacked_path.push_back(facade.FindEdge(source, target));
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}
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else
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{ // an overlay graph edge
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LevelID level = getNodeQureyLevel(partition, source, args...);
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CellID parent_cell_id = partition.GetCell(level, source);
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BOOST_ASSERT(parent_cell_id == partition.GetCell(level, target));
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LevelID sublevel = level - 1;
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// Here heaps can be reused, let's go deeper!
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forward_heap.Clear();
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reverse_heap.Clear();
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forward_heap.Insert(source, 0, {source});
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reverse_heap.Insert(target, 0, {target});
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// TODO: when structured bindings will be allowed change to
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// auto [subpath_weight, subpath_source, subpath_target, subpath] = ...
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EdgeWeight subpath_weight;
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NodeID subpath_source, subpath_target;
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std::vector<EdgeID> subpath;
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std::tie(subpath_weight, subpath_source, subpath_target, subpath) =
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search(facade, forward_heap, reverse_heap, sublevel, parent_cell_id);
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BOOST_ASSERT(!subpath.empty());
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BOOST_ASSERT(subpath_source == source);
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BOOST_ASSERT(subpath_target == target);
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unpacked_path.insert(unpacked_path.end(), subpath.begin(), subpath.end());
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}
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}
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return std::make_tuple(weight, source_node, target_node, std::move(unpacked_path));
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}
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} // namespace mld
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} // namespace routing_algorithms
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} // namespace engine
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} // namespace osrm
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#endif // OSRM_ENGINE_ROUTING_BASE_MLD_HPP
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