osrm-backend/src/extractor/graph_compressor.cpp
2016-08-24 10:34:07 +02:00

236 lines
9.7 KiB
C++

#include "extractor/graph_compressor.hpp"
#include "extractor/compressed_edge_container.hpp"
#include "extractor/restriction_map.hpp"
#include "util/dynamic_graph.hpp"
#include "util/node_based_graph.hpp"
#include "util/percent.hpp"
#include "util/simple_logger.hpp"
namespace osrm
{
namespace extractor
{
void GraphCompressor::Compress(const std::unordered_set<NodeID> &barrier_nodes,
const std::unordered_set<NodeID> &traffic_lights,
RestrictionMap &restriction_map,
util::NodeBasedDynamicGraph &graph,
CompressedEdgeContainer &geometry_compressor)
{
const unsigned original_number_of_nodes = graph.GetNumberOfNodes();
const unsigned original_number_of_edges = graph.GetNumberOfEdges();
util::Percent progress(original_number_of_nodes);
for (const NodeID node_v : util::irange(0u, original_number_of_nodes))
{
progress.PrintStatus(node_v);
// only contract degree 2 vertices
if (2 != graph.GetOutDegree(node_v))
{
continue;
}
// don't contract barrier node
if (barrier_nodes.end() != barrier_nodes.find(node_v))
{
continue;
}
// check if v is a via node for a turn restriction, i.e. a 'directed' barrier node
if (restriction_map.IsViaNode(node_v))
{
continue;
}
// reverse_e2 forward_e2
// u <---------- v -----------> w
// ----------> <-----------
// forward_e1 reverse_e1
//
// Will be compressed to:
//
// reverse_e1
// u <---------- w
// ---------->
// forward_e1
//
// If the edges are compatible.
const bool reverse_edge_order = graph.GetEdgeData(graph.BeginEdges(node_v)).reversed;
const EdgeID forward_e2 = graph.BeginEdges(node_v) + reverse_edge_order;
BOOST_ASSERT(SPECIAL_EDGEID != forward_e2);
BOOST_ASSERT(forward_e2 >= graph.BeginEdges(node_v) && forward_e2 < graph.EndEdges(node_v));
const EdgeID reverse_e2 = graph.BeginEdges(node_v) + 1 - reverse_edge_order;
BOOST_ASSERT(SPECIAL_EDGEID != reverse_e2);
BOOST_ASSERT(reverse_e2 >= graph.BeginEdges(node_v) && reverse_e2 < graph.EndEdges(node_v));
const EdgeData &fwd_edge_data2 = graph.GetEdgeData(forward_e2);
const EdgeData &rev_edge_data2 = graph.GetEdgeData(reverse_e2);
const NodeID node_w = graph.GetTarget(forward_e2);
BOOST_ASSERT(SPECIAL_NODEID != node_w);
BOOST_ASSERT(node_v != node_w);
const NodeID node_u = graph.GetTarget(reverse_e2);
BOOST_ASSERT(SPECIAL_NODEID != node_u);
BOOST_ASSERT(node_u != node_v);
const EdgeID forward_e1 = graph.FindEdge(node_u, node_v);
BOOST_ASSERT(SPECIAL_EDGEID != forward_e1);
BOOST_ASSERT(node_v == graph.GetTarget(forward_e1));
const EdgeID reverse_e1 = graph.FindEdge(node_w, node_v);
BOOST_ASSERT(SPECIAL_EDGEID != reverse_e1);
BOOST_ASSERT(node_v == graph.GetTarget(reverse_e1));
const EdgeData &fwd_edge_data1 = graph.GetEdgeData(forward_e1);
const EdgeData &rev_edge_data1 = graph.GetEdgeData(reverse_e1);
if (graph.FindEdgeInEitherDirection(node_u, node_w) != SPECIAL_EDGEID)
{
continue;
}
// this case can happen if two ways with different names overlap
if (fwd_edge_data1.name_id != rev_edge_data1.name_id ||
fwd_edge_data2.name_id != rev_edge_data2.name_id)
{
continue;
}
if (fwd_edge_data1.CanCombineWith(fwd_edge_data2) &&
rev_edge_data1.CanCombineWith(rev_edge_data2))
{
BOOST_ASSERT(graph.GetEdgeData(forward_e1).name_id ==
graph.GetEdgeData(reverse_e1).name_id);
BOOST_ASSERT(graph.GetEdgeData(forward_e2).name_id ==
graph.GetEdgeData(reverse_e2).name_id);
// Do not compress edge if it crosses a traffic signal.
// This can't be done in CanCombineWith, becase we only store the
// traffic signals in the `traffic_lights` list, which EdgeData
// doesn't have access to.
const bool has_node_penalty = traffic_lights.find(node_v) != traffic_lights.end();
if (has_node_penalty)
continue;
// Get distances before graph is modified
const int forward_weight1 = graph.GetEdgeData(forward_e1).distance;
const int forward_weight2 = graph.GetEdgeData(forward_e2).distance;
BOOST_ASSERT(0 != forward_weight1);
BOOST_ASSERT(0 != forward_weight2);
const int reverse_weight1 = graph.GetEdgeData(reverse_e1).distance;
const int reverse_weight2 = graph.GetEdgeData(reverse_e2).distance;
BOOST_ASSERT(0 != reverse_weight1);
BOOST_ASSERT(0 != reverse_weight2);
// add weight of e2's to e1
graph.GetEdgeData(forward_e1).distance += fwd_edge_data2.distance;
graph.GetEdgeData(reverse_e1).distance += rev_edge_data2.distance;
// extend e1's to targets of e2's
graph.SetTarget(forward_e1, node_w);
graph.SetTarget(reverse_e1, node_u);
/*
* Remember Lane Data for compressed parts. This handles scenarios where lane-data is
* only kept up until a traffic light.
*
* | |
* ---------------- |
* -^ | |
* ----------- |
* -v | |
* --------------- |
* | |
*
* u ------- v ---- w
*
* Since the edge is compressable, we can transfer:
* "left|right" (uv) and "" (uw) into a string with "left|right" (uw) for the compressed
* edge.
* Doing so, we might mess up the point from where the lanes are shown. It should be
* reasonable, since the announcements have to come early anyhow. So there is a
* potential danger in here, but it saves us from adding a lot of additional edges for
* turn-lanes. Without this,we would have to treat any turn-lane beginning/ending just
* like a barrier.
*/
const auto selectLaneID = [](const LaneDescriptionID front,
const LaneDescriptionID back) {
// A lane has tags: u - (front) - v - (back) - w
// During contraction, we keep only one of the tags. Usually the one closer to the
// intersection is preferred. If its empty, however, we keep the non-empty one
if (back == INVALID_LANE_DESCRIPTIONID)
return front;
return back;
};
graph.GetEdgeData(forward_e1).lane_description_id =
selectLaneID(graph.GetEdgeData(forward_e1).lane_description_id,
fwd_edge_data2.lane_description_id);
graph.GetEdgeData(reverse_e1).lane_description_id =
selectLaneID(graph.GetEdgeData(reverse_e1).lane_description_id,
rev_edge_data2.lane_description_id);
// remove e2's (if bidir, otherwise only one)
graph.DeleteEdge(node_v, forward_e2);
graph.DeleteEdge(node_v, reverse_e2);
// update any involved turn restrictions
restriction_map.FixupStartingTurnRestriction(node_u, node_v, node_w);
restriction_map.FixupArrivingTurnRestriction(node_u, node_v, node_w, graph);
restriction_map.FixupStartingTurnRestriction(node_w, node_v, node_u);
restriction_map.FixupArrivingTurnRestriction(node_w, node_v, node_u, graph);
// store compressed geometry in container
geometry_compressor.CompressEdge(
forward_e1, forward_e2, node_v, node_w, forward_weight1, forward_weight2);
geometry_compressor.CompressEdge(
reverse_e1, reverse_e2, node_v, node_u, reverse_weight1, reverse_weight2);
}
}
PrintStatistics(original_number_of_nodes, original_number_of_edges, graph);
// Repeate the loop, but now add all edges as uncompressed values.
// The function AddUncompressedEdge does nothing if the edge is already
// in the CompressedEdgeContainer.
for (const NodeID node_u : util::irange(0u, original_number_of_nodes))
{
for (const auto edge_id : util::irange(graph.BeginEdges(node_u), graph.EndEdges(node_u)))
{
const EdgeData &data = graph.GetEdgeData(edge_id);
const NodeID target = graph.GetTarget(edge_id);
geometry_compressor.AddUncompressedEdge(edge_id, target, data.distance);
}
}
}
void GraphCompressor::PrintStatistics(unsigned original_number_of_nodes,
unsigned original_number_of_edges,
const util::NodeBasedDynamicGraph &graph) const
{
unsigned new_node_count = 0;
unsigned new_edge_count = 0;
for (const auto i : util::irange(0u, graph.GetNumberOfNodes()))
{
if (graph.GetOutDegree(i) > 0)
{
++new_node_count;
new_edge_count += (graph.EndEdges(i) - graph.BeginEdges(i));
}
}
util::SimpleLogger().Write() << "Node compression ratio: "
<< new_node_count / (double)original_number_of_nodes;
util::SimpleLogger().Write() << "Edge compression ratio: "
<< new_edge_count / (double)original_number_of_edges;
}
}
}