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osrm-backend/src/engine/plugins/trip.cpp

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#include "engine/plugins/trip.hpp"
#include "engine/api/trip_api.hpp"
#include "engine/api/trip_parameters.hpp"
#include "engine/trip/trip_brute_force.hpp"
#include "engine/trip/trip_farthest_insertion.hpp"
#include "engine/trip/trip_nearest_neighbour.hpp"
#include "util/dist_table_wrapper.hpp" // to access the dist table more easily
#include "util/json_container.hpp"
#include <boost/assert.hpp>
#include <algorithm>
#include <cstdlib>
#include <iterator>
#include <limits>
#include <memory>
#include <string>
#include <utility>
#include <vector>
namespace osrm
{
namespace engine
{
namespace plugins
{
bool IsStronglyConnectedComponent(const util::DistTableWrapper<EdgeWeight> &result_table)
{
return std::find(std::begin(result_table), std::end(result_table), INVALID_EDGE_WEIGHT) ==
std::end(result_table);
}
bool IsSupportedParameterCombination(const bool fixed_start,
const bool fixed_end,
const bool roundtrip)
{
if (fixed_start && fixed_end && !roundtrip)
{
return true;
}
else if (roundtrip)
{
return true;
}
else
{
return false;
}
}
// given the node order in which to visit, compute the actual route (with geometry, travel time and
// so on) and return the result
InternalRouteResult TripPlugin::ComputeRoute(const RoutingAlgorithmsInterface &algorithms,
const std::vector<PhantomNode> &snapped_phantoms,
const std::vector<NodeID> &trip,
const bool roundtrip) const
{
InternalRouteResult min_route;
// given the final trip, compute total duration and return the route and location permutation
PhantomNodes viapoint;
// computes a roundtrip from the nodes in trip
for (auto node = trip.begin(); node < trip.end() - 1; ++node)
{
const auto from_node = *node;
const auto to_node = *std::next(node);
viapoint = PhantomNodes{snapped_phantoms[from_node], snapped_phantoms[to_node]};
min_route.segment_end_coordinates.emplace_back(viapoint);
}
// return back to the first node if it is a round trip
if (roundtrip)
{
viapoint = PhantomNodes{snapped_phantoms[trip.back()], snapped_phantoms[trip.front()]};
min_route.segment_end_coordinates.emplace_back(viapoint);
// trip comes out to be something like 0 1 4 3 2 0
BOOST_ASSERT(min_route.segment_end_coordinates.size() == trip.size());
}
else
{
// trip comes out to be something like 0 1 4 3 2, so the sizes don't match
BOOST_ASSERT(min_route.segment_end_coordinates.size() == trip.size() - 1);
}
min_route = algorithms.ShortestPathSearch(min_route.segment_end_coordinates, {false});
BOOST_ASSERT_MSG(min_route.shortest_path_weight < INVALID_EDGE_WEIGHT, "unroutable route");
return min_route;
}
void ManipulateTableForFSE(const std::size_t source_id,
const std::size_t destination_id,
util::DistTableWrapper<EdgeWeight> &result_table)
{
// ****************** Change Table *************************
// The following code manipulates the table and produces the new table for
// Trip with Fixed Start and End (TFSE). In the example the source is a
// and destination is c. The new table forces the roundtrip to start at
// source and end at destination by virtually squashing them together.
// This way the brute force and the farthest insertion algorithms don't
// have to be modified, and instead we can just pass a modified table to
// return a non-roundtrip "optimal" route from a start node to an end node.
// Original Table // New Table
// a b c d e // a b c d e
// a 0 15 36 34 30 // a 0 15 10000 34 30
// b 15 0 25 30 34 // b 10000 0 25 30 34
// c 36 25 0 18 32 // c 0 10000 0 10000 10000
// d 34 30 18 0 15 // d 10000 30 18 0 15
// e 30 34 32 15 0 // e 10000 34 32 15 0
// change parameters.source column
// set any node to source to impossibly high numbers so it will never
// try to use any node->source in the middle of the "optimal path"
for (std::size_t i = 0; i < result_table.GetNumberOfNodes(); i++)
{
if (i == source_id)
continue;
result_table.SetValue(i, source_id, INVALID_EDGE_WEIGHT);
}
// change parameters.destination row
// set destination to anywhere else to impossibly high numbers so it will
// never try to use destination->any node in the middle of the "optimal path"
for (std::size_t i = 0; i < result_table.GetNumberOfNodes(); i++)
{
if (i == destination_id)
continue;
result_table.SetValue(destination_id, i, INVALID_EDGE_WEIGHT);
}
// set destination->source to zero so roundtrip treats source and
// destination as one location
result_table.SetValue(destination_id, source_id, 0);
// set source->destination as very high number so algorithm is forced
// to find another path to get to destination
result_table.SetValue(source_id, destination_id, INVALID_EDGE_WEIGHT);
//********* End of changes to table *************************************
}
Status TripPlugin::HandleRequest(const RoutingAlgorithmsInterface &algorithms,
const api::TripParameters &parameters,
util::json::Object &json_result) const
{
if (!algorithms.HasShortestPathSearch())
{
return Error("NotImplemented",
"Shortest path search is not implemented for the chosen search algorithm.",
json_result);
}
if (!algorithms.HasManyToManySearch())
{
return Error("NotImplemented",
"Many to many search is not implemented for the chosen search algorithm.",
json_result);
}
BOOST_ASSERT(parameters.IsValid());
const auto number_of_locations = parameters.coordinates.size();
std::size_t source_id = INVALID_INDEX;
std::size_t destination_id = INVALID_INDEX;
if (parameters.source == api::TripParameters::SourceType::First)
{
source_id = 0;
}
if (parameters.destination == api::TripParameters::DestinationType::Last)
{
BOOST_ASSERT(number_of_locations > 0);
destination_id = number_of_locations - 1;
}
bool fixed_start = (source_id == 0);
bool fixed_end = (destination_id == number_of_locations - 1);
if (!IsSupportedParameterCombination(fixed_start, fixed_end, parameters.roundtrip))
{
return Error("NotImplemented", "This request is not supported", json_result);
}
// enforce maximum number of locations for performance reasons
if (max_locations_trip > 0 && static_cast<int>(number_of_locations) > max_locations_trip)
{
return Error("TooBig", "Too many trip coordinates", json_result);
}
if (!CheckAllCoordinates(parameters.coordinates))
{
return Error("InvalidValue", "Invalid coordinate value.", json_result);
}
if (!CheckAlgorithms(parameters, algorithms, json_result))
return Status::Error;
const auto &facade = algorithms.GetFacade();
auto phantom_node_pairs = GetPhantomNodes(facade, parameters);
if (phantom_node_pairs.size() != number_of_locations)
{
return Error("NoSegment",
std::string("Could not find a matching segment for coordinate ") +
std::to_string(phantom_node_pairs.size()),
json_result);
}
BOOST_ASSERT(phantom_node_pairs.size() == number_of_locations);
if (fixed_start && fixed_end && (source_id >= parameters.coordinates.size() ||
destination_id >= parameters.coordinates.size()))
{
return Error("InvalidValue", "Invalid source or destination value.", json_result);
}
auto snapped_phantoms = SnapPhantomNodes(phantom_node_pairs);
BOOST_ASSERT(snapped_phantoms.size() == number_of_locations);
// compute the duration table of all phantom nodes
auto result_duration_table = util::DistTableWrapper<EdgeWeight>(
algorithms
.ManyToManySearch(
snapped_phantoms, {}, {}, /*requestDistance*/ false, /*requestDuration*/ true)
.first,
number_of_locations);
if (result_duration_table.size() == 0)
{
return Status::Error;
}
const constexpr std::size_t BF_MAX_FEASABLE = 10;
BOOST_ASSERT_MSG(result_duration_table.size() == number_of_locations * number_of_locations,
"Distance Table has wrong size");
if (!IsStronglyConnectedComponent(result_duration_table))
{
return Error("NoTrips", "No trip visiting all destinations possible.", json_result);
}
if (fixed_start && fixed_end)
{
ManipulateTableForFSE(source_id, destination_id, result_duration_table);
}
std::vector<NodeID> duration_trip;
duration_trip.reserve(number_of_locations);
// get an optimized order in which the destinations should be visited
if (number_of_locations < BF_MAX_FEASABLE)
{
duration_trip = trip::BruteForceTrip(number_of_locations, result_duration_table);
}
else
{
duration_trip = trip::FarthestInsertionTrip(number_of_locations, result_duration_table);
}
// rotate result such that roundtrip starts at node with index 0
// thist first if covers scenarios: !fixed_end || fixed_start || (fixed_start && fixed_end)
if (!fixed_end || fixed_start)
{
auto desired_start_index = std::find(std::begin(duration_trip), std::end(duration_trip), 0);
BOOST_ASSERT(desired_start_index != std::end(duration_trip));
std::rotate(std::begin(duration_trip), desired_start_index, std::end(duration_trip));
}
else if (fixed_end && !fixed_start && parameters.roundtrip)
{
auto desired_start_index =
std::find(std::begin(duration_trip), std::end(duration_trip), destination_id);
BOOST_ASSERT(desired_start_index != std::end(duration_trip));
std::rotate(std::begin(duration_trip), desired_start_index, std::end(duration_trip));
}
// get the route when visiting all destinations in optimized order
InternalRouteResult route =
ComputeRoute(algorithms, snapped_phantoms, duration_trip, parameters.roundtrip);
// get api response
const std::vector<std::vector<NodeID>> trips = {duration_trip};
const std::vector<InternalRouteResult> routes = {route};
api::TripAPI trip_api{facade, parameters};
trip_api.MakeResponse(trips, routes, snapped_phantoms, json_result);
return Status::Ok;
}
}
}
}
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