osrm-backend/RoutingAlgorithms/ShortestPathRouting.h

/*
    open source routing machine
    Copyright (C) Dennis Luxen, others 2010

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU AFFERO General Public License as published by
the Free Software Foundation; either version 3 of the License, or
any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
or see http://www.gnu.org/licenses/agpl.txt.
 */



#ifndef SHORTESTPATHROUTING_H_
#define SHORTESTPATHROUTING_H_

#include <boost/assert.hpp>

#include "BasicRoutingInterface.h"
#include "../DataStructures/SearchEngineData.h"

template<class DataFacadeT>
class ShortestPathRouting : public BasicRoutingInterface<DataFacadeT>{
    typedef BasicRoutingInterface<DataFacadeT> super;
    typedef SearchEngineData::QueryHeap QueryHeap;
    SearchEngineData & engine_working_data;

public:
    ShortestPathRouting(
        DataFacadeT * facade,
        SearchEngineData & engine_working_data
    ) :
        super(facade),
        engine_working_data(engine_working_data)
    {}

    ~ShortestPathRouting() {}

    void operator()(
        std::vector<PhantomNodes> & phantom_nodes_vector,
        RawRouteData & raw_route_data
    ) const {
        BOOST_FOREACH(
            const PhantomNodes & phantom_node_pair,
            phantom_nodes_vector
        ){
            if(!phantom_node_pair.AtLeastOnePhantomNodeIsUINTMAX()) {
                raw_route_data.lengthOfShortestPath = INT_MAX;
                raw_route_data.lengthOfAlternativePath = INT_MAX;
                return;
            }
        }
        int distance1 = 0;
        int distance2 = 0;

        bool search_from_1st_node = true;
        bool search_from_2nd_node = true;
        NodeID middle1 = UINT_MAX;
        NodeID middle2 = UINT_MAX;
        std::vector<NodeID> packed_path1;
        std::vector<NodeID> packed_path2;

        engine_working_data.InitializeOrClearFirstThreadLocalStorage(
            super::facade->GetNumberOfNodes()
        );
        engine_working_data.InitializeOrClearSecondThreadLocalStorage(
            super::facade->GetNumberOfNodes()
        );
        engine_working_data.InitializeOrClearThirdThreadLocalStorage(
            super::facade->GetNumberOfNodes()
        );

        QueryHeap & forward_heap1 = *(engine_working_data.forwardHeap);
        QueryHeap & reverse_heap1 = *(engine_working_data.backwardHeap);
        QueryHeap & forward_heap2 = *(engine_working_data.forwardHeap2);
        QueryHeap & reverse_heap2 = *(engine_working_data.backwardHeap2);

        //Get distance to next pair of target nodes.
        BOOST_FOREACH(
            const PhantomNodes & phantom_node_pair,
            phantom_nodes_vector
        ){
            forward_heap1.Clear();	forward_heap2.Clear();
            reverse_heap1.Clear();	reverse_heap2.Clear();
            int local_upper_bound1 = INT_MAX;
            int local_upper_bound2 = INT_MAX;

            middle1 = UINT_MAX;
            middle2 = UINT_MAX;

            //insert new starting nodes into forward heap, adjusted by previous distances.
            if(search_from_1st_node) {
                forward_heap1.Insert(
                    phantom_node_pair.startPhantom.edgeBasedNode,
                    -phantom_node_pair.startPhantom.weight1,
                    phantom_node_pair.startPhantom.edgeBasedNode
                );
                // INFO("fw1: " << phantom_node_pair.startPhantom.edgeBasedNode << "´, w: " << -phantom_node_pair.startPhantom.weight1);
                forward_heap2.Insert(
                    phantom_node_pair.startPhantom.edgeBasedNode,
                    -phantom_node_pair.startPhantom.weight1,
                    phantom_node_pair.startPhantom.edgeBasedNode
                );
                // INFO("fw2: " << phantom_node_pair.startPhantom.edgeBasedNode << "´, w: " << -phantom_node_pair.startPhantom.weight1);
           }
            if(phantom_node_pair.startPhantom.isBidirected() && search_from_2nd_node) {
                forward_heap1.Insert(
                    phantom_node_pair.startPhantom.edgeBasedNode+1,
                    -phantom_node_pair.startPhantom.weight2,
                    phantom_node_pair.startPhantom.edgeBasedNode+1
                );
                // INFO("fw1: " << phantom_node_pair.startPhantom.edgeBasedNode+1 << "´, w: " << -phantom_node_pair.startPhantom.weight2);
                forward_heap2.Insert(
                    phantom_node_pair.startPhantom.edgeBasedNode+1,
                    -phantom_node_pair.startPhantom.weight2,
                    phantom_node_pair.startPhantom.edgeBasedNode+1
                );
                // INFO("fw2: " << phantom_node_pair.startPhantom.edgeBasedNode+1 << "´, w: " << -phantom_node_pair.startPhantom.weight2);
            }

            //insert new backward nodes into backward heap, unadjusted.
            reverse_heap1.Insert(
                phantom_node_pair.targetPhantom.edgeBasedNode,
                phantom_node_pair.targetPhantom.weight1,
                phantom_node_pair.targetPhantom.edgeBasedNode
            );
            // INFO("rv1: " << phantom_node_pair.targetPhantom.edgeBasedNode << ", w;" << phantom_node_pair.targetPhantom.weight1 );
            if(phantom_node_pair.targetPhantom.isBidirected() ) {
                reverse_heap2.Insert(
                    phantom_node_pair.targetPhantom.edgeBasedNode+1,
                    phantom_node_pair.targetPhantom.weight2,
                    phantom_node_pair.targetPhantom.edgeBasedNode+1
                );
                // INFO("rv2: " << phantom_node_pair.targetPhantom.edgeBasedNode+1 << ", w;" << phantom_node_pair.targetPhantom.weight2 );
           }
            const int forward_offset =  super::ComputeEdgeOffset(
                                            phantom_node_pair.startPhantom
                                        );
            const int reverse_offset =  super::ComputeEdgeOffset(
                                            phantom_node_pair.targetPhantom
                                        );

            //run two-Target Dijkstra routing step.
            while(0 < (forward_heap1.Size() + reverse_heap1.Size() )){
                if( !forward_heap1.Empty()){
                    super::RoutingStep(
                        forward_heap1,
                        reverse_heap1,
                        &middle1,
                        &local_upper_bound1,
                        forward_offset,
                        true
                    );
                }
                if( !reverse_heap1.Empty() ){
                    super::RoutingStep(
                        reverse_heap1,
                        forward_heap1,
                        &middle1,
                        &local_upper_bound1,
                        reverse_offset,
                        false
                    );
                }
            }
            if( !reverse_heap2.Empty() ) {
                while(0 < (forward_heap2.Size() + reverse_heap2.Size() )){
                    if( !forward_heap2.Empty() ){
                        super::RoutingStep(
                            forward_heap2,
                            reverse_heap2,
                            &middle2,
                            &local_upper_bound2,
                            forward_offset,
                            true
                        );
                    }
                    if( !reverse_heap2.Empty() ){
                        super::RoutingStep(
                            reverse_heap2,
                            forward_heap2,
                            &middle2,
                            &local_upper_bound2,
                            reverse_offset,
                            false
                        );
                    }
                }
            }

            //No path found for both target nodes?
            if(
                (INT_MAX == local_upper_bound1) &&
                (INT_MAX == local_upper_bound2)
            ) {
                raw_route_data.lengthOfShortestPath = INT_MAX;
                raw_route_data.lengthOfAlternativePath = INT_MAX;
                return;
            }
            if(UINT_MAX == middle1) {
                search_from_1st_node = false;
            }
            if(UINT_MAX == middle2) {
                search_from_2nd_node = false;
            }

            //Was at most one of the two paths not found?
            BOOST_ASSERT_MSG(
                (INT_MAX != distance1 || INT_MAX != distance2),
                "no path found"
            );

            //Unpack paths if they exist
            std::vector<NodeID> temporary_packed_path1;
            std::vector<NodeID> temporary_packed_path2;
            if(INT_MAX != local_upper_bound1) {
                super::RetrievePackedPathFromHeap(
                    forward_heap1,
                    reverse_heap1,
                    middle1,
                    temporary_packed_path1
                );
            }

            if(INT_MAX != local_upper_bound2) {
                super::RetrievePackedPathFromHeap(
                    forward_heap2,
                    reverse_heap2,
                    middle2,
                    temporary_packed_path2
                );
            }

            //if one of the paths was not found, replace it with the other one.
            if( temporary_packed_path1.empty() ) {
                temporary_packed_path1.insert(
                    temporary_packed_path1.end(),
                    temporary_packed_path2.begin(),
                    temporary_packed_path2.end()
                );
                local_upper_bound1 = local_upper_bound2;
            }
            if( temporary_packed_path2.empty() ) {
                temporary_packed_path2.insert(
                    temporary_packed_path2.end(),
                    temporary_packed_path1.begin(),
                    temporary_packed_path1.end()
                );
                local_upper_bound2 = local_upper_bound1;
            }

            BOOST_ASSERT_MSG(
                temporary_packed_path1.empty() &&
                temporary_packed_path2.empty(),
                "tempory packed paths not empty"
            );

            //Plug paths together, s.t. end of packed path is begin of temporary packed path
            if( !packed_path1.empty() && !packed_path2.empty() ) {
                if(
                    temporary_packed_path1.front() ==
                    temporary_packed_path2.front()
                ) {
                    //both new route segments start with the same node
                    //thus, one of the packedPath must go.
                    BOOST_ASSERT_MSG(
                        (packed_path1.size() == packed_path2.size() ) ||
                        (packed_path1.back() != packed_path2.back() ),
                        "packed paths must be different"
                    );

                    if( packed_path1.back() == temporary_packed_path1.front()) {
                        packed_path2.clear();
                        packed_path2.insert(
                            packed_path2.end(),
                            packed_path1.begin(),
                            packed_path1.end()
                        );
                        distance2 = distance1;
                    } else {
                        packed_path1.clear();
                        packed_path1.insert(
                            packed_path1.end(),
                            packed_path2.begin(),
                            packed_path2.end()
                        );
                        distance1 = distance2;
                    }
                } else  {
                    //packed paths 1 and 2 may need to switch.
                    if( packed_path1.back() != temporary_packed_path1.front()) {
                        packed_path1.swap(packed_path2);
                        std::swap(distance1, distance2);
                    }
                }
            }
            packed_path1.insert(
                packed_path1.end(),
                temporary_packed_path1.begin(),
                temporary_packed_path1.end()
            );
            packed_path2.insert(
                packed_path2.end(),
                temporary_packed_path2.begin(),
                temporary_packed_path2.end()
            );

            if(
                (packed_path1.back() == packed_path2.back()) &&
                phantom_node_pair.targetPhantom.isBidirected()
            ) {
                const NodeID last_node_id = packed_path2.back();
                search_from_1st_node &= !(last_node_id == phantom_node_pair.targetPhantom.edgeBasedNode+1);
                search_from_2nd_node &= !(last_node_id == phantom_node_pair.targetPhantom.edgeBasedNode);
            }

            distance1 += local_upper_bound1;
            distance2 += local_upper_bound2;
        }

        if( distance1 > distance2 ) {
            std::swap( packed_path1, packed_path2 );
        }
        remove_consecutive_duplicates_from_vector(packed_path1);
        super::UnpackPath(packed_path1, raw_route_data.computedShortestPath);
        raw_route_data.lengthOfShortestPath = std::min(distance1, distance2);
    }
};

#endif /* SHORTESTPATHROUTING_H_ */