osrm-backend/Contractor/Contractor.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 CONTRACTOR_H_INCLUDED
#define CONTRACTOR_H_INCLUDED
#include <algorithm>
#include <limits>
#include <vector>

#include <cfloat>
#include <ctime>

#include <boost/foreach.hpp>
#include <boost/lambda/lambda.hpp>
#include <boost/make_shared.hpp>
#include <boost/shared_ptr.hpp>

#include "TemporaryStorage.h"
#include "../DataStructures/BinaryHeap.h"
#include "../DataStructures/DeallocatingVector.h"
#include "../DataStructures/DynamicGraph.h"
#include "../DataStructures/Percent.h"
#include "../DataStructures/XORFastHash.h"
#include "../DataStructures/XORFastHashStorage.h"
#include "../Util/OpenMPWrapper.h"
#include "../Util/StringUtil.h"

class Contractor {

private:
    struct _ContractorEdgeData {
        _ContractorEdgeData() :
            distance(0), id(0), originalEdges(0), shortcut(0), forward(0), backward(0), originalViaNodeID(false) {}
        _ContractorEdgeData( unsigned _distance, unsigned _originalEdges, unsigned _id, bool _shortcut, bool _forward, bool _backward) :
            distance(_distance), id(_id), originalEdges(std::min((unsigned)1<<28, _originalEdges) ), shortcut(_shortcut), forward(_forward), backward(_backward), originalViaNodeID(false) {}
        unsigned distance;
        unsigned id;
        unsigned originalEdges:28;
        bool shortcut:1;
        bool forward:1;
        bool backward:1;
        bool originalViaNodeID:1;
    } data;

    struct _HeapData {
        short hop;
        bool target;
        _HeapData() : hop(0), target(false) {}
        _HeapData( short h, bool t ) : hop(h), target(t) {}
    };

    typedef DynamicGraph< _ContractorEdgeData > _DynamicGraph;
    //    typedef BinaryHeap< NodeID, NodeID, int, _HeapData, ArrayStorage<NodeID, NodeID> > _Heap;
    typedef BinaryHeap< NodeID, NodeID, int, _HeapData, XORFastHashStorage<NodeID, NodeID> > _Heap;
    typedef _DynamicGraph::InputEdge _ContractorEdge;

    struct _ThreadData {
        _Heap heap;
        std::vector< _ContractorEdge > insertedEdges;
        std::vector< NodeID > neighbours;
        _ThreadData( NodeID nodes ): heap( nodes ) { }
    };

    struct _PriorityData {
        int depth;
        _PriorityData() : depth(0) { }
    };

    struct _ContractionInformation {
        int edgesDeleted;
        int edgesAdded;
        int originalEdgesDeleted;
        int originalEdgesAdded;
        _ContractionInformation() : edgesDeleted(0), edgesAdded(0), originalEdgesDeleted(0), originalEdgesAdded(0) {}
    };

    struct _RemainingNodeData {
        _RemainingNodeData() : id (0), isIndependent(false) {}
        NodeID id:31;
        bool isIndependent:1;
    };

    struct _NodePartitionor {
        inline bool operator()(_RemainingNodeData & nodeData ) const {
            return !nodeData.isIndependent;
        }
    };

public:

    template<class ContainerT >
    Contractor( int nodes, ContainerT& inputEdges) {
        std::vector< _ContractorEdge > edges;
        edges.reserve(inputEdges.size()*2);

        typename ContainerT::deallocation_iterator diter = inputEdges.dbegin();
        typename ContainerT::deallocation_iterator dend  = inputEdges.dend();

        _ContractorEdge newEdge;
        while(diter!=dend) {
            newEdge.source = diter->source();
            newEdge.target = diter->target();
            newEdge.data = _ContractorEdgeData( (std::max)((int)diter->weight(), 1 ),  1,  diter->id(),  false,  diter->isForward(),  diter->isBackward());

            assert( newEdge.data.distance > 0 );
#ifndef NDEBUG
            if ( newEdge.data.distance > 24 * 60 * 60 * 10 ) {
                WARN("Edge weight large -> " << newEdge.data.distance);
            }
#endif
            edges.push_back( newEdge );
            std::swap( newEdge.source, newEdge.target );
            newEdge.data.forward = diter->isBackward();
            newEdge.data.backward = diter->isForward();
            edges.push_back( newEdge );
            ++diter;
        }
        //clear input vector and trim the current set of edges with the well-known swap trick
        inputEdges.clear();
        sort( edges.begin(), edges.end() );
        NodeID edge = 0;
        for ( NodeID i = 0; i < edges.size(); ) {
            const NodeID source = edges[i].source;
            const NodeID target = edges[i].target;
            const NodeID id = edges[i].data.id;
            //remove eigenloops
            if ( source == target ) {
                i++;
                continue;
            }
            _ContractorEdge forwardEdge;
            _ContractorEdge backwardEdge;
            forwardEdge.source = backwardEdge.source = source;
            forwardEdge.target = backwardEdge.target = target;
            forwardEdge.data.forward = backwardEdge.data.backward = true;
            forwardEdge.data.backward = backwardEdge.data.forward = false;
            forwardEdge.data.shortcut = backwardEdge.data.shortcut = false;
            forwardEdge.data.id = backwardEdge.data.id = id;
            forwardEdge.data.originalEdges = backwardEdge.data.originalEdges = 1;
            forwardEdge.data.distance = backwardEdge.data.distance = std::numeric_limits< int >::max();
            //remove parallel edges
            while ( i < edges.size() && edges[i].source == source && edges[i].target == target ) {
                if ( edges[i].data.forward )
                    forwardEdge.data.distance = std::min( edges[i].data.distance, forwardEdge.data.distance );
                if ( edges[i].data.backward )
                    backwardEdge.data.distance = std::min( edges[i].data.distance, backwardEdge.data.distance );
                i++;
            }
            //merge edges (s,t) and (t,s) into bidirectional edge
            if ( forwardEdge.data.distance == backwardEdge.data.distance ) {
                if ( (int)forwardEdge.data.distance != std::numeric_limits< int >::max() ) {
                    forwardEdge.data.backward = true;
                    edges[edge++] = forwardEdge;
                }
            } else { //insert seperate edges
                if ( ((int)forwardEdge.data.distance) != std::numeric_limits< int >::max() ) {
                    edges[edge++] = forwardEdge;
                }
                if ( (int)backwardEdge.data.distance != std::numeric_limits< int >::max() ) {
                    edges[edge++] = backwardEdge;
                }
            }
        }
        std::cout << "merged " << edges.size() - edge << " edges out of " << edges.size() << std::endl;
        edges.resize( edge );
        _graph = boost::make_shared<_DynamicGraph>( nodes, edges );
        edges.clear();
        std::vector<_ContractorEdge>().swap(edges);
        //        unsigned maxdegree = 0;
        //        NodeID highestNode = 0;
        //
        //        for(unsigned i = 0; i < _graph->GetNumberOfNodes(); ++i) {
        //            unsigned degree = _graph->EndEdges(i) - _graph->BeginEdges(i);
        //            if(degree > maxdegree) {
        //                maxdegree = degree;
        //                highestNode = i;
        //            }
        //        }
        //
        //        INFO("edges at node with id " << highestNode << " has degree " << maxdegree);
        //        for(unsigned i = _graph->BeginEdges(highestNode); i < _graph->EndEdges(highestNode); ++i) {
        //            INFO(" ->(" << highestNode << "," << _graph->GetTarget(i) << "); via: " << _graph->GetEdgeData(i).via);
        //        }

        //Create temporary file

        //        GetTemporaryFileName(temporaryEdgeStorageFilename);
        temporaryStorageSlotID = TemporaryStorage::GetInstance().allocateSlot();
        std::cout << "contractor finished initalization" << std::endl;
    }

    ~Contractor() {
        //Delete temporary file
        //        remove(temporaryEdgeStorageFilename.c_str());
        TemporaryStorage::GetInstance().deallocateSlot(temporaryStorageSlotID);
    }

    void Run() {
        const NodeID numberOfNodes = _graph->GetNumberOfNodes();
        Percent p (numberOfNodes);

        const unsigned maxThreads = omp_get_max_threads();
        std::vector < _ThreadData* > threadData;
        for ( unsigned threadNum = 0; threadNum < maxThreads; ++threadNum ) {
            threadData.push_back( new _ThreadData( numberOfNodes ) );
        }
        std::cout << "Contractor is using " << maxThreads << " threads" << std::endl;

        NodeID numberOfContractedNodes = 0;
        std::vector< _RemainingNodeData > remainingNodes( numberOfNodes );
        std::vector< float > nodePriority( numberOfNodes );
        std::vector< _PriorityData > nodeData( numberOfNodes );

        //initialize the variables
#pragma omp parallel for schedule ( guided )
        for ( int x = 0; x < ( int ) numberOfNodes; ++x )
            remainingNodes[x].id = x;

        std::cout << "initializing elimination PQ ..." << std::flush;
#pragma omp parallel
        {
            _ThreadData* data = threadData[omp_get_thread_num()];
#pragma omp parallel for schedule ( guided )
            for ( int x = 0; x < ( int ) numberOfNodes; ++x ) {
                nodePriority[x] = _Evaluate( data, &nodeData[x], x );
            }
        }
        std::cout << "ok" << std::endl << "preprocessing ..." << std::flush;

        bool flushedContractor = false;
        while ( numberOfContractedNodes < numberOfNodes ) {
            if(!flushedContractor && (numberOfContractedNodes > (numberOfNodes*0.65) ) ){
                DeallocatingVector<_ContractorEdge> newSetOfEdges; //this one is not explicitely cleared since it goes out of scope anywa
                std::cout << " [flush " << numberOfContractedNodes << " nodes] " << std::flush;

                //Delete old heap data to free memory that we need for the coming operations
                BOOST_FOREACH(_ThreadData * data, threadData)
                	delete data;
                threadData.clear();


                //Create new priority array
                std::vector<float> newNodePriority(remainingNodes.size());
                //this map gives the old IDs from the new ones, necessary to get a consistent graph at the end of contraction
                oldNodeIDFromNewNodeIDMap.resize(remainingNodes.size());
                //this map gives the new IDs from the old ones, necessary to remap targets from the remaining graph
                std::vector<NodeID> newNodeIDFromOldNodeIDMap(numberOfNodes, UINT_MAX);

                //build forward and backward renumbering map and remap ids in remainingNodes and Priorities.
                for(unsigned newNodeID = 0; newNodeID < remainingNodes.size(); ++newNodeID) {
                    //create renumbering maps in both directions
                    oldNodeIDFromNewNodeIDMap[newNodeID] = remainingNodes[newNodeID].id;
                    newNodeIDFromOldNodeIDMap[remainingNodes[newNodeID].id] = newNodeID;
                    newNodePriority[newNodeID] = nodePriority[remainingNodes[newNodeID].id];
                    remainingNodes[newNodeID].id = newNodeID;
                }
                TemporaryStorage & tempStorage = TemporaryStorage::GetInstance();
                //Write dummy number of edges to temporary file
                //        		std::ofstream temporaryEdgeStorage(temporaryEdgeStorageFilename.c_str(), std::ios::binary);
                long initialFilePosition = tempStorage.tell(temporaryStorageSlotID);
                unsigned numberOfTemporaryEdges = 0;
                tempStorage.writeToSlot(temporaryStorageSlotID, (char*)&numberOfTemporaryEdges, sizeof(unsigned));

                //walk over all nodes
                for(unsigned i = 0; i < _graph->GetNumberOfNodes(); ++i) {
                    //INFO("Restructuring node " << i << "|" << _graph->GetNumberOfNodes());
                    const NodeID start = i;
                    for(_DynamicGraph::EdgeIterator currentEdge = _graph->BeginEdges(start); currentEdge < _graph->EndEdges(start); ++currentEdge) {
                        _DynamicGraph::EdgeData & data = _graph->GetEdgeData(currentEdge);
                        const NodeID target = _graph->GetTarget(currentEdge);
                        if(UINT_MAX == newNodeIDFromOldNodeIDMap[i] ){
                            //Save edges of this node w/o renumbering.
                            tempStorage.writeToSlot(temporaryStorageSlotID, (char*)&start,  sizeof(NodeID));
                            tempStorage.writeToSlot(temporaryStorageSlotID, (char*)&target, sizeof(NodeID));
                            tempStorage.writeToSlot(temporaryStorageSlotID, (char*)&data,   sizeof(_DynamicGraph::EdgeData));
                            ++numberOfTemporaryEdges;
                        }else {
                            //node is not yet contracted.
                            //add (renumbered) outgoing edges to new DynamicGraph.
                            _ContractorEdge newEdge;
                            newEdge.source = newNodeIDFromOldNodeIDMap[start];
                            newEdge.target = newNodeIDFromOldNodeIDMap[target];
                            newEdge.data = data;
                            newEdge.data.originalViaNodeID = true;
                            assert(UINT_MAX != newNodeIDFromOldNodeIDMap[start] );
                            assert(UINT_MAX != newNodeIDFromOldNodeIDMap[target]);
                            newSetOfEdges.push_back(newEdge);
                        }
                    }
                }
                //Note the number of temporarily stored edges
                tempStorage.seek(temporaryStorageSlotID, initialFilePosition);
                tempStorage.writeToSlot(temporaryStorageSlotID, (char*)&numberOfTemporaryEdges, sizeof(unsigned));

                //        		INFO("Flushed " << numberOfTemporaryEdges << " edges to disk");

                //Delete map from old NodeIDs to new ones.
                std::vector<NodeID>().swap(newNodeIDFromOldNodeIDMap);

                //Replace old priorities array by new one
                nodePriority.swap(newNodePriority);
                //Delete old nodePriority vector
                std::vector<float>().swap(newNodePriority);
                //old Graph is removed
                _graph.reset();

                //create new graph
                std::sort(newSetOfEdges.begin(), newSetOfEdges.end());
                _graph = boost::make_shared<_DynamicGraph>(remainingNodes.size(), newSetOfEdges);

                newSetOfEdges.clear();
                flushedContractor = true;

                //INFO: MAKE SURE THIS IS THE LAST OPERATION OF THE FLUSH!
                //reinitialize heaps and ThreadData objects with appropriate size
                for ( unsigned threadNum = 0; threadNum < maxThreads; ++threadNum ) {
                    threadData.push_back( new _ThreadData( _graph->GetNumberOfNodes() ) );
                }
            }

            const int last = ( int ) remainingNodes.size();
#pragma omp parallel
            {
                //determine independent node set
                _ThreadData* const data = threadData[omp_get_thread_num()];
#pragma omp for schedule ( guided )
                for ( int i = 0; i < last; ++i ) {
                    const NodeID node = remainingNodes[i].id;
                    remainingNodes[i].isIndependent = _IsIndependent( nodePriority/*, nodeData*/, data, node );
                }
            }
            _NodePartitionor functor;
            const std::vector < _RemainingNodeData >::const_iterator first = stable_partition( remainingNodes.begin(), remainingNodes.end(), functor );
            const int firstIndependent = first - remainingNodes.begin();
            //contract independent nodes
#pragma omp parallel
            {
                _ThreadData* data = threadData[omp_get_thread_num()];
#pragma omp for schedule ( guided ) nowait
                for ( int position = firstIndependent ; position < last; ++position ) {
                    NodeID x = remainingNodes[position].id;
                    _Contract< false > ( data, x );
                    //nodePriority[x] = -1;
                }

                std::sort( data->insertedEdges.begin(), data->insertedEdges.end() );
            }
#pragma omp parallel
            {
                _ThreadData* data = threadData[omp_get_thread_num()];
#pragma omp for schedule ( guided ) nowait
                for ( int position = firstIndependent ; position < last; ++position ) {
                    NodeID x = remainingNodes[position].id;
                    _DeleteIncomingEdges( data, x );
                }
            }
            //insert new edges
            for ( unsigned threadNum = 0; threadNum < maxThreads; ++threadNum ) {
                _ThreadData& data = *threadData[threadNum];
                BOOST_FOREACH(const _ContractorEdge& edge, data.insertedEdges) {
                    _DynamicGraph::EdgeIterator currentEdgeID = _graph->FindEdge(edge.source, edge.target);
                    if(currentEdgeID < _graph->EndEdges(edge.source) ) {
                        _DynamicGraph::EdgeData & currentEdgeData = _graph->GetEdgeData(currentEdgeID);
                        if( currentEdgeData.shortcut
                                && edge.data.forward == currentEdgeData.forward
                                && edge.data.backward == currentEdgeData.backward ) {
                            currentEdgeData.distance = std::min(currentEdgeData.distance, edge.data.distance);
                            continue;
                        }
                    }
                    _graph->InsertEdge( edge.source, edge.target, edge.data );
                }
                data.insertedEdges.clear();
            }
            //update priorities
#pragma omp parallel
            {
                _ThreadData* data = threadData[omp_get_thread_num()];
#pragma omp for schedule ( guided ) nowait
                for ( int position = firstIndependent ; position < last; ++position ) {
                    NodeID x = remainingNodes[position].id;
                    _UpdateNeighbours( nodePriority, nodeData, data, x );
                }
            }
            //remove contracted nodes from the pool
            numberOfContractedNodes += last - firstIndependent;
            remainingNodes.resize( firstIndependent );
            std::vector< _RemainingNodeData>( remainingNodes ).swap( remainingNodes );
            //            unsigned maxdegree = 0;
            //            unsigned avgdegree = 0;
            //            unsigned mindegree = UINT_MAX;
            //            unsigned quaddegree = 0;
            //
            //            for(unsigned i = 0; i < remainingNodes.size(); ++i) {
            //                unsigned degree = _graph->EndEdges(remainingNodes[i].first) - _graph->BeginEdges(remainingNodes[i].first);
            //                if(degree > maxdegree)
            //                    maxdegree = degree;
            //                if(degree < mindegree)
            //                    mindegree = degree;
            //
            //                avgdegree += degree;
            //                quaddegree += (degree*degree);
            //            }
            //
            //            avgdegree /= std::max((unsigned)1,(unsigned)remainingNodes.size() );
            //            quaddegree /= std::max((unsigned)1,(unsigned)remainingNodes.size() );
            //
            //            INFO("rest: " << remainingNodes.size() << ", max: " << maxdegree << ", min: " << mindegree << ", avg: " << avgdegree << ", quad: " << quaddegree);

            p.printStatus(numberOfContractedNodes);
        }
        BOOST_FOREACH(_ThreadData * data, threadData)
        	delete data;
        threadData.clear();
    }

    template< class Edge >
    inline void GetEdges( DeallocatingVector< Edge >& edges ) {
        Percent p (_graph->GetNumberOfNodes());
        INFO("Getting edges of minimized graph");
        NodeID numberOfNodes = _graph->GetNumberOfNodes();
        if(oldNodeIDFromNewNodeIDMap.size()) {
            for ( NodeID node = 0; node < numberOfNodes; ++node ) {
                p.printStatus(node);
                for ( _DynamicGraph::EdgeIterator edge = _graph->BeginEdges( node ), endEdges = _graph->EndEdges( node ); edge < endEdges; ++edge ) {
                    const NodeID target = _graph->GetTarget( edge );
                    const _DynamicGraph::EdgeData& data = _graph->GetEdgeData( edge );
                    Edge newEdge;
                    newEdge.source = oldNodeIDFromNewNodeIDMap[node];
                    newEdge.target = oldNodeIDFromNewNodeIDMap[target];
                    assert(UINT_MAX != newEdge.source);
                    assert(UINT_MAX != newEdge.target);

                    newEdge.data.distance = data.distance;
                    newEdge.data.shortcut = data.shortcut;
                    if(!data.originalViaNodeID)
                        newEdge.data.id = oldNodeIDFromNewNodeIDMap[data.id];
                    else
                        newEdge.data.id = data.id;

                    assert(newEdge.data.id != UINT_MAX);
                    newEdge.data.forward = data.forward;
                    newEdge.data.backward = data.backward;
                    edges.push_back( newEdge );
                }
            }
        }
        INFO("Renumbered edges of minimized graph, freeing space");
        _graph.reset();
        std::vector<NodeID>().swap(oldNodeIDFromNewNodeIDMap);
        INFO("Loading temporary edges");

        //        std::ifstream temporaryEdgeStorage(temporaryEdgeStorageFilename.c_str(), std::ios::binary);
        TemporaryStorage & tempStorage = TemporaryStorage::GetInstance();
        //Also get the edges from temporary storage
        unsigned numberOfTemporaryEdges = 0;
        tempStorage.readFromSlot(temporaryStorageSlotID, (char*)&numberOfTemporaryEdges, sizeof(unsigned));
        //loads edges of graph before renumbering, no need for further numbering action.
        NodeID start;
        NodeID target;
        //edges.reserve(edges.size()+numberOfTemporaryEdges);
        _DynamicGraph::EdgeData data;
        for(unsigned i = 0; i < numberOfTemporaryEdges; ++i) {
            tempStorage.readFromSlot(temporaryStorageSlotID, (char*)&start,  sizeof(NodeID));
            tempStorage.readFromSlot(temporaryStorageSlotID, (char*)&target, sizeof(NodeID));
            tempStorage.readFromSlot(temporaryStorageSlotID, (char*)&data,   sizeof(_DynamicGraph::EdgeData));
            Edge newEdge;
            newEdge.source =  start;
            newEdge.target = target;
            newEdge.data.distance = data.distance;
            newEdge.data.shortcut = data.shortcut;
            newEdge.data.id = data.id;
            newEdge.data.forward = data.forward;
            newEdge.data.backward = data.backward;
            edges.push_back( newEdge );
        }
        tempStorage.deallocateSlot(temporaryStorageSlotID);
        INFO("Hierarchy has " << edges.size() << " edges");
    }

private:
    inline void _Dijkstra( const int maxDistance, const unsigned numTargets, const int maxNodes, _ThreadData* const data, const NodeID middleNode ){

        _Heap& heap = data->heap;

        int nodes = 0;
        unsigned targetsFound = 0;
        while ( heap.Size() > 0 ) {
            const NodeID node = heap.DeleteMin();
            const int distance = heap.GetKey( node );
            const short currentHop = heap.GetData( node ).hop+1;

            if ( ++nodes > maxNodes )
                return;
            //Destination settled?
            if ( distance > maxDistance )
                return;

            if ( heap.GetData( node ).target ) {
                ++targetsFound;
                if ( targetsFound >= numTargets )
                    return;
            }

            //iterate over all edges of node
            for ( _DynamicGraph::EdgeIterator edge = _graph->BeginEdges( node ), endEdges = _graph->EndEdges( node ); edge != endEdges; ++edge ) {
                const _ContractorEdgeData& data = _graph->GetEdgeData( edge );
                if ( !data.forward )
                    continue;
                const NodeID to = _graph->GetTarget( edge );
                if(middleNode == to)
                    continue;
                const int toDistance = distance + data.distance;

                //New Node discovered -> Add to Heap + Node Info Storage
                if ( !heap.WasInserted( to ) )
                    heap.Insert( to, toDistance, _HeapData(currentHop, false) );

                //Found a shorter Path -> Update distance
                else if ( toDistance < heap.GetKey( to ) ) {
                    heap.DecreaseKey( to, toDistance );
                    heap.GetData( to ).hop = currentHop;
                }
            }
        }
    }

    inline float _Evaluate( _ThreadData* const data, _PriorityData* const nodeData, const NodeID node){
        _ContractionInformation stats;

        //perform simulated contraction
        _Contract< true> ( data, node, &stats );

        // Result will contain the priority
        float result;
        if ( 0 == (stats.edgesDeleted*stats.originalEdgesDeleted) )
            result = 1 * nodeData->depth;
        else
            result =  2 * ((( float ) stats.edgesAdded ) / stats.edgesDeleted ) + 4 * ((( float ) stats.originalEdgesAdded ) / stats.originalEdgesDeleted ) + 1 * nodeData->depth;
        assert( result >= 0 );
        return result;
    }

    template< bool Simulate >
    inline bool _Contract( _ThreadData* data, NodeID node, _ContractionInformation* stats = NULL ) {
        _Heap& heap = data->heap;
        int insertedEdgesSize = data->insertedEdges.size();
        std::vector< _ContractorEdge >& insertedEdges = data->insertedEdges;

        for ( _DynamicGraph::EdgeIterator inEdge = _graph->BeginEdges( node ), endInEdges = _graph->EndEdges( node ); inEdge != endInEdges; ++inEdge ) {
            const _ContractorEdgeData& inData = _graph->GetEdgeData( inEdge );
            const NodeID source = _graph->GetTarget( inEdge );
            if ( Simulate ) {
                assert( stats != NULL );
                ++stats->edgesDeleted;
                stats->originalEdgesDeleted += inData.originalEdges;
            }
            if ( !inData.backward )
                continue;

            heap.Clear();
            heap.Insert( source, 0, _HeapData() );
            int maxDistance = 0;
            unsigned numTargets = 0;

            for ( _DynamicGraph::EdgeIterator outEdge = _graph->BeginEdges( node ), endOutEdges = _graph->EndEdges( node ); outEdge != endOutEdges; ++outEdge ) {
                const _ContractorEdgeData& outData = _graph->GetEdgeData( outEdge );
                if ( !outData.forward )
                    continue;
                const NodeID target = _graph->GetTarget( outEdge );
                const int pathDistance = inData.distance + outData.distance;
                maxDistance = std::max( maxDistance, pathDistance );
                if ( !heap.WasInserted( target ) ) {
                    heap.Insert( target, INT_MAX, _HeapData( 0, true ) );
                    ++numTargets;
                }
            }

            if( Simulate )
                _Dijkstra( maxDistance, numTargets, 1000, data, node );
            else
                _Dijkstra( maxDistance, numTargets, 2000, data, node );

            for ( _DynamicGraph::EdgeIterator outEdge = _graph->BeginEdges( node ), endOutEdges = _graph->EndEdges( node ); outEdge != endOutEdges; ++outEdge ) {
                const _ContractorEdgeData& outData = _graph->GetEdgeData( outEdge );
                if ( !outData.forward )
                    continue;
                const NodeID target = _graph->GetTarget( outEdge );
                const int pathDistance = inData.distance + outData.distance;
                const int distance = heap.GetKey( target );
                if ( pathDistance < distance ) {
                    if ( Simulate ) {
                        assert( stats != NULL );
                        stats->edgesAdded+=2;
                        stats->originalEdgesAdded += 2* ( outData.originalEdges + inData.originalEdges );
                    } else {
                        _ContractorEdge newEdge;
                        newEdge.source = source;
                        newEdge.target = target;
                        newEdge.data = _ContractorEdgeData( pathDistance, outData.originalEdges + inData.originalEdges, node/*, 0, inData.turnInstruction*/, true, true, false);;
                        insertedEdges.push_back( newEdge );
                        std::swap( newEdge.source, newEdge.target );
                        newEdge.data.forward = false;
                        newEdge.data.backward = true;
                        insertedEdges.push_back( newEdge );
                    }
                }
            }
        }
        if ( !Simulate ) {
            for ( int i = insertedEdgesSize, iend = insertedEdges.size(); i < iend; ++i ) {
                bool found = false;
                for ( int other = i + 1 ; other < iend ; ++other ) {
                    if ( insertedEdges[other].source != insertedEdges[i].source )
                        continue;
                    if ( insertedEdges[other].target != insertedEdges[i].target )
                        continue;
                    if ( insertedEdges[other].data.distance != insertedEdges[i].data.distance )
                        continue;
                    if ( insertedEdges[other].data.shortcut != insertedEdges[i].data.shortcut )
                        continue;
                    insertedEdges[other].data.forward |= insertedEdges[i].data.forward;
                    insertedEdges[other].data.backward |= insertedEdges[i].data.backward;
                    found = true;
                    break;
                }
                if ( !found )
                    insertedEdges[insertedEdgesSize++] = insertedEdges[i];
            }
            insertedEdges.resize( insertedEdgesSize );
        }
        return true;
    }

    inline void _DeleteIncomingEdges( _ThreadData* data, const NodeID node ) {
        std::vector< NodeID >& neighbours = data->neighbours;
        neighbours.clear();

        //find all neighbours
        for ( _DynamicGraph::EdgeIterator e = _graph->BeginEdges( node ) ; e < _graph->EndEdges( node ) ; ++e ) {
            const NodeID u = _graph->GetTarget( e );
            if ( u != node )
                neighbours.push_back( u );
        }
        //eliminate duplicate entries ( forward + backward edges )
        std::sort( neighbours.begin(), neighbours.end() );
        neighbours.resize( std::unique( neighbours.begin(), neighbours.end() ) - neighbours.begin() );

        for ( int i = 0, e = ( int ) neighbours.size(); i < e; ++i ) {
            _graph->DeleteEdgesTo( neighbours[i], node );
        }
    }

    inline bool _UpdateNeighbours( std::vector< float > & priorities, std::vector< _PriorityData > & nodeData, _ThreadData* const data, const NodeID node) {
        std::vector< NodeID >& neighbours = data->neighbours;
        neighbours.clear();

        //find all neighbours
        for ( _DynamicGraph::EdgeIterator e = _graph->BeginEdges( node ), endEdges = _graph->EndEdges( node ) ; e < endEdges ; ++e ) {
            const NodeID u = _graph->GetTarget( e );
            if ( u == node )
                continue;
            neighbours.push_back( u );
            nodeData[u].depth = (std::max)(nodeData[node].depth + 1, nodeData[u].depth );
        }
        //eliminate duplicate entries ( forward + backward edges )
        std::sort( neighbours.begin(), neighbours.end() );
        neighbours.resize( std::unique( neighbours.begin(), neighbours.end() ) - neighbours.begin() );

        BOOST_FOREACH(const NodeID u, neighbours) {
            priorities[u] = _Evaluate( data, &( nodeData )[u], u );
        }
        return true;
    }

    inline bool _IsIndependent( const std::vector< float >& priorities/*, const std::vector< _PriorityData >& nodeData*/, _ThreadData* const data, NodeID node ) const {
        const double priority = priorities[node];

        std::vector< NodeID >& neighbours = data->neighbours;
        neighbours.clear();

        for ( _DynamicGraph::EdgeIterator e = _graph->BeginEdges( node ) ; e < _graph->EndEdges( node ) ; ++e ) {
            const NodeID target = _graph->GetTarget( e );
            if(node==target)
                continue;
            const double targetPriority = priorities[target];
            assert( targetPriority >= 0 );
            //found a neighbour with lower priority?
            if ( priority > targetPriority )
                return false;
            //tie breaking
            if ( fabs(priority - targetPriority) < FLT_EPSILON && bias(node, target) ) {
                return false;
            }
            neighbours.push_back( target );
        }

        std::sort( neighbours.begin(), neighbours.end() );
        neighbours.resize( std::unique( neighbours.begin(), neighbours.end() ) - neighbours.begin() );

        //examine all neighbours that are at most 2 hops away
        BOOST_FOREACH(const NodeID u, neighbours) {
            for ( _DynamicGraph::EdgeIterator e = _graph->BeginEdges( u ) ; e < _graph->EndEdges( u ) ; ++e ) {
                const NodeID target = _graph->GetTarget( e );
                if(node==target)
                    continue;

                const double targetPriority = priorities[target];
                assert( targetPriority >= 0 );
                //found a neighbour with lower priority?
                if ( priority > targetPriority)
                    return false;
                //tie breaking
                if ( fabs(priority - targetPriority) < FLT_EPSILON && bias(node, target) ) {
                    return false;
                }
            }
        }
        return true;
    }


    /**
     * This bias function takes up 22 assembly instructions in total on X86
     */
    inline bool bias(const NodeID a, const NodeID b) const {
        unsigned short hasha = fastHash(a);
        unsigned short hashb = fastHash(b);

        //The compiler optimizes that to conditional register flags but without branching statements!
        if(hasha != hashb)
            return hasha < hashb;
        return a < b;
    }

    boost::shared_ptr<_DynamicGraph> _graph;
    std::vector<_DynamicGraph::InputEdge> contractedEdges;
    unsigned temporaryStorageSlotID;
    std::vector<NodeID> oldNodeIDFromNewNodeIDMap;
    XORFastHash fastHash;
};

#endif // CONTRACTOR_H_INCLUDED