osrm-backend/plugins/round_trip.hpp

/*

Copyright (c) 2015, Project OSRM contributors
All rights reserved.

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are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list
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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
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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;
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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
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*/

#ifndef ROUND_TRIP_HPP
#define ROUND_TRIP_HPP

#include "plugin_base.hpp"

#include "../algorithms/object_encoder.hpp"
#include "../algorithms/tarjan_scc.hpp"
#include "../routing_algorithms/tsp_nearest_neighbour.hpp"
#include "../routing_algorithms/tsp_farthest_insertion.hpp"
#include "../routing_algorithms/tsp_brute_force.hpp"
#include "../data_structures/query_edge.hpp"
#include "../data_structures/search_engine.hpp"
#include "../data_structures/matrix_graph_wrapper.hpp"
#include "../data_structures/restriction.hpp"
#include "../data_structures/restriction_map.hpp"
#include "../descriptors/descriptor_base.hpp"
#include "../descriptors/json_descriptor.hpp"
#include "../util/json_renderer.hpp"
#include "../util/make_unique.hpp"
#include "../util/string_util.hpp"
#include "../util/timing_util.hpp"
#include "../util/simple_logger.hpp"
#include "../util/dist_table_wrapper.hpp"

#include <osrm/json_container.hpp>
#include <boost/assert.hpp>

#include <cstdlib>
#include <algorithm>
#include <memory>
#include <unordered_map>
#include <string>
#include <utility>
#include <vector>
#include <limits>
#include <map>
#include <iterator>

#include <iostream>

template <class DataFacadeT> class RoundTripPlugin final : public BasePlugin
{
  private:
    std::string descriptor_string;
    DataFacadeT *facade;
    std::unique_ptr<SearchEngine<DataFacadeT>> search_engine_ptr;

  public:
    explicit RoundTripPlugin(DataFacadeT *facade)
        : descriptor_string("trip"), facade(facade)
    {
        search_engine_ptr = osrm::make_unique<SearchEngine<DataFacadeT>>(facade);
    }

    const std::string GetDescriptor() const override final { return descriptor_string; }

    void GetPhantomNodes(const RouteParameters &route_parameters, PhantomNodeArray & phantom_node_vector) {
        const bool checksum_OK = (route_parameters.check_sum == facade->GetCheckSum());

        // find phantom nodes for all input coords
        for (const auto i : osrm::irange<std::size_t>(0, route_parameters.coordinates.size())) {
            // if client hints are helpful, encode hints
            if (checksum_OK && i < route_parameters.hints.size() &&
                !route_parameters.hints[i].empty()) {
                PhantomNode current_phantom_node;
                ObjectEncoder::DecodeFromBase64(route_parameters.hints[i], current_phantom_node);
                if (current_phantom_node.is_valid(facade->GetNumberOfNodes()))
                {
                    phantom_node_vector[i].emplace_back(std::move(current_phantom_node));
                    continue;
                }
            }
            facade->IncrementalFindPhantomNodeForCoordinate(route_parameters.coordinates[i],
                                                            phantom_node_vector[i], 1);
            if (phantom_node_vector[i].size() > 1) {
                phantom_node_vector[i].erase(std::begin(phantom_node_vector[i]));
            }
            BOOST_ASSERT(phantom_node_vector[i].front().is_valid(facade->GetNumberOfNodes()));
        }
    }

    struct SCC_Component{
        SCC_Component(std::vector<NodeID> in_component,
                      std::vector<size_t> in_component_range)
                      : component(in_component), component_range(in_component_range) {
                        component_range.push_back(in_component.size());
                      };

        SCC_Component(std::vector<NodeID> in_component)
                      : component(in_component), component_range({0, in_component.size()}) {
                      };

        std::size_t GetNumberOfComponents() const{
            return component_range.size() - 1;
        }

        const std::vector<NodeID> component;
        std::vector<size_t> component_range;
    };

    SCC_Component SplitUnaccessibleLocations(const std::size_t number_of_locations,
                                    const DistTableWrapper<EdgeWeight> & result_table) {

        // Run TarjanSCC
        auto wrapper = std::make_shared<MatrixGraphWrapper<EdgeWeight>>(result_table.GetTable(), number_of_locations);
        auto scc = TarjanSCC<MatrixGraphWrapper<EdgeWeight>>(wrapper);
        scc.run();

        std::vector<size_t> range_insertion;
        std::vector<size_t> component_range;
        range_insertion.reserve(scc.get_number_of_components());
        component_range.reserve(scc.get_number_of_components());

        std::vector<NodeID> components(number_of_locations, 0);

        auto prefix = 0;
        for (size_t j = 0; j < scc.get_number_of_components(); ++j){
            range_insertion.push_back(prefix);
            component_range.push_back(prefix);
            prefix += scc.get_component_size(j);
        }

        for (size_t i = 0; i < number_of_locations; ++i) {
            components[range_insertion[scc.get_component_id(i)]] = i;
            ++range_insertion[scc.get_component_id(i)];
        }

        return SCC_Component(components, component_range);
    }

    void SetLocPermutationOutput(const std::vector<NodeID> & loc_permutation, osrm::json::Object & json_result){
        osrm::json::Array json_loc_permutation;
        json_loc_permutation.values.insert(std::end(json_loc_permutation.values), std::begin(loc_permutation), std::end(loc_permutation));
        json_result.values["loc_permutation"] = json_loc_permutation;
    }

    void SetDistanceOutput(const int distance, osrm::json::Object & json_result) {
        json_result.values["distance"] = distance;
    }
    void SetRuntimeOutput(const float runtime, osrm::json::Object & json_result) {
        json_result.values["runtime"] = runtime;
    }

    void SetGeometry(const RouteParameters &route_parameters,
                     const InternalRouteResult & min_route,
                     osrm::json::Object & json_result) {
        // return geometry result to json
        std::unique_ptr<BaseDescriptor<DataFacadeT>> descriptor;
        descriptor = osrm::make_unique<JSONDescriptor<DataFacadeT>>(facade);

        descriptor->SetConfig(route_parameters);
        descriptor->Run(min_route, json_result);
    }

    void ComputeRoute(const PhantomNodeArray & phantom_node_vector,
                      const RouteParameters & route_parameters,
                      const std::vector<NodeID> & trip,
                      InternalRouteResult & min_route) {
        // given he final trip, compute total distance and return the route and location permutation
        PhantomNodes viapoint;
        for (auto it = std::begin(trip); it != std::end(trip); ++it) {
            const auto from_node = *it;
            const auto to_node = std::next(it) != std::end(trip) ? *std::next(it) : *std::begin(trip);
            viapoint = PhantomNodes{phantom_node_vector[from_node][0], phantom_node_vector[to_node][0]};
            min_route.segment_end_coordinates.emplace_back(viapoint);
        }

        search_engine_ptr->shortest_path(min_route.segment_end_coordinates, route_parameters.uturns, min_route);
    }

    int HandleRequest(const RouteParameters &route_parameters,
                      osrm::json::Object &json_result) override final
    {
        // check if all inputs are coordinates
        if (!check_all_coordinates(route_parameters.coordinates)) {
            return 400;
        }

        // get phantom nodes
        PhantomNodeArray phantom_node_vector(route_parameters.coordinates.size());
        GetPhantomNodes(route_parameters, phantom_node_vector);
        auto number_of_locations = phantom_node_vector.size();

        // compute the distance table of all phantom nodes
        const auto result_table = DistTableWrapper<EdgeWeight>(*search_engine_ptr->distance_table(phantom_node_vector),
                                                               number_of_locations);
        if (result_table.size() == 0){
            return 400;
        }

        const constexpr std::size_t BF_MAX_FEASABLE = 10;
        BOOST_ASSERT_MSG(result_table.size() > 0, "Distance Table is empty.");

        // get scc components
        SCC_Component scc = [&](){
            if (*std::max_element(result_table.begin(), result_table.end()) == INVALID_EDGE_WEIGHT) {
                // compute all scc with tarjan
                return SplitUnaccessibleLocations(number_of_locations, result_table);
            } else {
                // whole graph is one scc
                std::vector<NodeID> location_ids(number_of_locations);
                std::iota(std::begin(location_ids), std::end(location_ids), 0);
                return SCC_Component(location_ids);
            }
        }();


        using NodeIDIterator = typename std::vector<NodeID>::const_iterator;

        std::vector<std::vector<NodeID>> res_route;
        TIMER_START(tsp);
        //run TSP computation for every SCC
        for(auto k = 0; k < scc.GetNumberOfComponents(); ++k) {
            const auto component_size = scc.component_range[k+1] - scc.component_range[k];
            if (component_size > 1) {
                std::vector<NodeID> scc_route;
                NodeIDIterator start = std::begin(scc.component) + scc.component_range[k];
                NodeIDIterator end = std::begin(scc.component) + scc.component_range[k+1];

                // Compute the TSP with the given algorithm
                if (route_parameters.tsp_algo == "BF" && route_parameters.coordinates.size() < BF_MAX_FEASABLE) {
                    SimpleLogger().Write() << "Running brute force";
                    scc_route = osrm::tsp::BruteForceTSP(start, end, number_of_locations, result_table);
                    res_route.push_back(scc_route);
                } else if (route_parameters.tsp_algo == "NN") {
                    SimpleLogger().Write() << "Running nearest neighbour";
                    scc_route = osrm::tsp::NearestNeighbourTSP(start, end, number_of_locations, result_table);
                    res_route.push_back(scc_route);
                } else if (route_parameters.tsp_algo == "FI") {
                    SimpleLogger().Write() << "Running farthest insertion";
                    scc_route = osrm::tsp::FarthestInsertionTSP(start, end, number_of_locations, result_table);
                    res_route.push_back(scc_route);
                } else{
                    SimpleLogger().Write() << "Running farthest insertion";
                    scc_route = osrm::tsp::FarthestInsertionTSP(start, end, number_of_locations, result_table);
                    res_route.push_back(scc_route);
                }

                SimpleLogger().Write() << "Route #"
                                       << k << ": "
                                       << [&scc_route](){
                                               std::string s = "";
                                               for (auto x : scc_route) {
                                                   s += std::to_string(x) + " ";
                                               }
                                               return s;
                                           }();
            }
        }
        std::vector<InternalRouteResult> comp_route (res_route.size());
        for (auto r = 0; r < res_route.size(); ++r) {
            ComputeRoute(phantom_node_vector, route_parameters, res_route[r], comp_route[r]);
        }
        TIMER_STOP(tsp);

        SetRuntimeOutput(TIMER_MSEC(tsp), json_result);
        //TODO
        SetLocPermutationOutput(res_route[0], json_result);

        std::unique_ptr<BaseDescriptor<DataFacadeT>> descriptor;
        descriptor = osrm::make_unique<JSONDescriptor<DataFacadeT>>(facade);
        descriptor->SetConfig(route_parameters);
        auto dist = 0;
        for (auto r : comp_route) {
            dist += r.shortest_path_length;
            // SetGeometry(route_parameters, r, json_result);
            descriptor->Run(r, json_result);
        }
        SetDistanceOutput(dist, json_result);



        return 200;
    }

};

#endif // ROUND_TRIP_HPP