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Handles distinction of no-route vs invalid-route in mld alternatives

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The viaroute plugin always expects a route to be there potentially
with invalid edge weight to represent no-route-found. By switching
to the many-route-result for the mld alternatives algorithm we might
return an empty many-route-result invalidating the post-condition.
This commit is contained in:
Daniel J. Hofmann 2017-07-22 12:36:53 +02:00
parent 58811d8f5c
commit f7c8bac3fd
2 changed files with 12 additions and 2 deletions
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5
src/engine/plugins/viaroute.cpp
View File

@ -120,9 +120,12 @@ Status ViaRoutePlugin::HandleRequest(const RoutingAlgorithmsInterface &algorithm
routes = algorithms.ShortestPathSearch(start_end_nodes, route_parameters.continue_straight); routes = algorithms.ShortestPathSearch(start_end_nodes, route_parameters.continue_straight);
} }
// The post condition for all path searches is we have at least one route in our result.
// This route might be invalid by means of INVALID_EDGE_WEIGHT as shortest path weight.
BOOST_ASSERT(!routes.routes.empty());
// we can only know this after the fact, different SCC ids still // we can only know this after the fact, different SCC ids still
// allow for connection in one direction. // allow for connection in one direction.
BOOST_ASSERT(!routes.routes.empty());
if (routes.routes[0].is_valid()) if (routes.routes[0].is_valid())
{ {

9
src/engine/routing_algorithms/alternative_path_mld.cpp
View File

@ -792,8 +792,15 @@ InternalManyRoutesResult alternativePathSearch(SearchEngineData<Algorithm> &sear
shortest_path_via_it->node != SPECIAL_NODEID && shortest_path_via_it->node != SPECIAL_NODEID &&
shortest_path_via_it->weight != INVALID_EDGE_WEIGHT; shortest_path_via_it->weight != INVALID_EDGE_WEIGHT;
// Care needs to be taken to meet the call sites post condition.
// We must return at least one route, even if it's an invalid one.
if (!has_shortest_path) if (!has_shortest_path)
return InternalManyRoutesResult{}; {
InternalRouteResult invalid;
invalid.shortest_path_weight = INVALID_EDGE_WEIGHT;
invalid.segment_end_coordinates = {phantom_node_pair};
return invalid;
}
NodeID shortest_path_via = shortest_path_via_it->node; NodeID shortest_path_via = shortest_path_via_it->node;
EdgeWeight shortest_path_weight = shortest_path_via_it->weight; EdgeWeight shortest_path_weight = shortest_path_via_it->weight;