[traffic] Exclude roundabouts from decoded locations (with exceptions)

Signed-off-by: mvglasow <michael -at- vonglasow.com>

data/test_data/traff/DE-RoundaboutEndpoint.xml

@@ -0,0 +1,58 @@
+<!--
+    Test cases for reference points inside a roundabout.
+    If the roundabout itself is included in the decoded location, the message would
+    affect all roads which connect to it, resulting in incorrect routing, especially
+    in the case of closure events. For this reason, we must truncate roundabouts if
+    they occur at the start or end of the decoded location.
+-->
+<feed>
+  <message id="tmc:d.1.12:d.1.13962.p.5,11" receive_time="2018-07-27T10:22:22+02:00" update_time="2018-07-27T08:43:15Z" expiration_time="2018-07-27T09:43:15Z" urgency="URGENT">
+    <location fuzziness="LOW_RES" directionality="BOTH_DIRECTIONS" road_class="SECONDARY" road_ref="L87">
+      <from junction_name="Rheinau-Freistett/B36">+48.661098 +7.936800</from>
+      <to junction_name="Gambsheim (F)">+48.683701 +7.916600</to>
+    </location>
+    <events>
+      <event class="CONSTRUCTION" type="CONSTRUCTION_CONSTRUCTION_WORK">
+      </event>
+      <event class="RESTRICTION" type="RESTRICTION_CLOSED">
+      </event>
+    </events>
+  </message>
+  <message id="tmc:d.1.12:d.1.26212.p.5,11" receive_time="2018-07-27T10:21:49+02:00" update_time="2018-07-27T08:42:41Z" expiration_time="2018-07-27T09:42:41Z" urgency="URGENT">
+    <location fuzziness="LOW_RES" directionality="BOTH_DIRECTIONS" road_class="PRIMARY" road_ref="B428">
+      <from junction_name="Hackenheim">+49.822948 +7.906900</from>
+      <to junction_name="Frei-Laubersheim">+49.803650 +7.901450</to>
+    </location>
+    <events>
+      <event class="CONSTRUCTION" type="CONSTRUCTION_LONGTERM_ROADWORKS">
+      </event>
+      <event class="RESTRICTION" type="RESTRICTION_CLOSED">
+      </event>
+    </events>
+  </message>
+  <message id="tmc:d.1.12:d.1.48638.n.9,11" receive_time="2018-07-27T10:11:06+02:00" update_time="2018-07-27T08:31:43Z" expiration_time="2018-07-27T09:31:43Z" urgency="URGENT">
+    <location fuzziness="LOW_RES" directionality="BOTH_DIRECTIONS" road_class="PRIMARY" road_ref="B272">
+      <from junction_name="Hochstadt">+49.239750 +8.222300</from>
+      <to junction_name="Weingarten">+49.253448 +8.268100</to>
+    </location>
+    <events>
+      <event class="CONSTRUCTION" type="CONSTRUCTION_ROADWORKS">
+      </event>
+      <event class="RESTRICTION" type="RESTRICTION_CLOSED_AHEAD">
+      </event>
+    </events>
+  </message>
+  <message id="tmc:d.1.12:d.1.56576.n.9,11" receive_time="2018-07-27T10:22:53+02:00" update_time="2018-07-27T08:43:45Z" expiration_time="2018-07-27T09:43:45Z" urgency="URGENT">
+    <location fuzziness="LOW_RES" directionality="ONE_DIRECTION" road_class="PRIMARY" road_ref="B417">
+      <from junction_name="Diez">+50.372398 +8.038500</from>
+      <to junction_name="Diez">+50.370850 +8.004050</to>
+    </location>
+    <events>
+      <event class="CONSTRUCTION" type="CONSTRUCTION_RESURFACING_WORK">
+      </event>
+      <event class="RESTRICTION" type="RESTRICTION_CLOSED">
+        <supplementary_info class="VEHICLE" type="S_VEHICLE_THROUGH_TRAFFIC"/>
+      </event>
+    </events>
+  </message>
+</feed>

libs/routing/directions_engine.cpp

@@ -85,6 +85,7 @@ void DirectionsEngine::LoadPathAttributes(FeatureID const & featureId, LoadedPat
   pathSegment.m_isOneWay = m_onewayChecker(types);
 
   pathSegment.m_roadNameInfo.m_isLink = pathSegment.m_isLink;
+  pathSegment.m_roadNameInfo.m_onRoundabout = pathSegment.m_onRoundabout;
   pathSegment.m_roadNameInfo.m_junction_ref = ft->GetMetadata(feature::Metadata::FMD_JUNCTION_REF);
   pathSegment.m_roadNameInfo.m_destination_ref = ft->GetMetadata(feature::Metadata::FMD_DESTINATION_REF);
   pathSegment.m_roadNameInfo.m_destination = ft->GetMetadata(feature::Metadata::FMD_DESTINATION);

libs/routing/route.hpp

@@ -121,6 +121,10 @@ public:
      * @brief Whether the road is of a link type.
      */
     bool m_isLink = false;
+    /**
+     * @brief Whether the road is part of a roundabout.
+     */
+    bool m_onRoundabout = false;
 
     RoadNameInfo() = default;
     RoadNameInfo(std::string name) : m_name(std::move(name)) {}

libs/traffxml/traff_decoder.cpp

@@ -1030,6 +1030,32 @@ void RoutingTraffDecoder::DecodeLocationDirection(traffxml::TraffMessage & messa
 
     TruncateRoute(rsegments, checkpoints);
 
+    /*
+     * `m_onRoundabout` is set only for the first segment after the junction. In order to identify
+     * all roundabout segments, cache the last segment with `m_onRoundabout` set. Any subsequent
+     * segment with the same MWM and feature ID is also a roundabout segment.
+     */
+    routing::Segment lastRoundaboutSegment;
+
+    /*
+     * We usually discard roundabouts, unless the location is a point (`at` point set) or the entire
+     * decoded location is a roundabout.
+     */
+    bool keepRoundabouts = true;
+
+    if (!message.m_location.value().m_at)
+      for (auto & rsegment : rsegments)
+      {
+        if (rsegment.GetRoadNameInfo().m_onRoundabout)
+          lastRoundaboutSegment = rsegment.GetSegment();
+        else if ((rsegment.GetSegment().GetMwmId() != lastRoundaboutSegment.GetMwmId())
+            || (rsegment.GetSegment().GetFeatureId() != lastRoundaboutSegment.GetFeatureId()))
+        {
+          keepRoundabouts = false;
+          break;
+        }
+      }
+
     if (!backwards && message.m_location.value().m_at && !message.m_location.value().m_to)
       // from–at in forward direction, add last segment
       AddDecodedSegment(decoded, rsegments.back().GetSegment());
@@ -1070,6 +1096,19 @@ void RoutingTraffDecoder::DecodeLocationDirection(traffxml::TraffMessage & messa
       {
         routing::Segment & segment = rsegment.GetSegment();
 
+        // Skip roundabouts to avoid side effects on crossing roads
+        if (!keepRoundabouts)
+        {
+          if (rsegment.GetRoadNameInfo().m_onRoundabout)
+          {
+            lastRoundaboutSegment = segment;
+            continue;
+          }
+          else if ((segment.GetMwmId() == lastRoundaboutSegment.GetMwmId())
+              && (segment.GetFeatureId() == lastRoundaboutSegment.GetFeatureId()))
+            continue;
+        }
+
         // If we have more than two checkpoints, fake segments can occur in the middle, skip them.
         if (segment.GetMwmId() == routing::kFakeNumMwmId)
           continue;