Supporting Continuous Skyline Queries in Dynamically Weighted Road Networks

Algorithm 2

Compute the distance between two vertices in a hub graph.

input source vertex s and destination vertex t

output d(s,t)

Steps:

to reducer:

S.include(s); // define set S,add s to S

T=V-S; // set V include all vertices in the road network

while(T)

R=GetNeighborRoute(s,S,T); // find all routes between s and neighbor vertices of S in T as R

foreach r in R

if r. ConVedgeNum>=2

R.delete(r); // if r contains more than 2 adjacent virtual edges, delete r from R

continue();

else if r. VedgeNum>=1

r. Vedges.get(); // if r contains virtual edge,sent this virtual edge into input cache of mapper

r.length.compute(); // compute length of r

r=R.GetShortest(); // pick the shortest route,add its ends to S

S.include(r.end);

T.delete(r.end);

if(r.end==t) // return result when reaches destination t

return r.length;

to mapper:

Vedge.get(); // get virtual edges from input cache

Vedge.length=GetLength(Vedge.id);

Vedge.sent(); // sent length of virtual edges into output cache