[tracking] Pull request #5526 review fixesbeta-663

2 files changed, 6 insertions, 1 deletions

diff --git a/routing/routing_session.cpp b/routing/routing_session.cpp
index 2e6f65c812..7a613102d9 100644
--- a/routing/routing_session.cpp
+++ b/routing/routing_session.cpp
@@ -447,10 +447,13 @@ traffic::SpeedGroup RoutingSession::MatchTraffic(
   if (!routeMatchingInfo.IsMatched())
     return SpeedGroup::Unknown;
 
-  threads::MutexGuard guard(m_routingSessionMutex);
   size_t const index = routeMatchingInfo.GetIndexInRoute();
+  threads::MutexGuard guard(m_routingSessionMutex);
   vector<traffic::SpeedGroup> const & traffic = m_route->GetTraffic();
 
+  if (traffic.empty())
+    return SpeedGroup::Unknown;
+
   if (index >= traffic.size())
   {
     LOG(LERROR, ("Invalid index", index, "in RouteMatchingInfo, traffic.size():", traffic.size()));
diff --git a/routing/routing_session.hpp b/routing/routing_session.hpp
index 63e8c05af5..a94a102dc3 100644
--- a/routing/routing_session.hpp
+++ b/routing/routing_session.hpp
@@ -126,6 +126,8 @@ public:
 
   void MatchLocationToRoute(location::GpsInfo & location,
                             location::RouteMatchingInfo & routeMatchingInfo) const;
+  // Get traffic speed for the current route position.
+  // Returns SpeedGroup::Unknown if any trouble happens: position doesn't match with route or something else.
   traffic::SpeedGroup MatchTraffic(location::RouteMatchingInfo const & routeMatchingInfo) const;
 
   void SetUserCurrentPosition(m2::PointD const & position);