[traffic] Cache routing session state, introduce IsObserverInhibited()

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

libs/map/traffic_manager.cpp

@@ -206,8 +206,7 @@ void TrafficManager::OnChangeRoutingSessionState(routing::SessionState previous,
   LOG(LINFO, ("Routing session state changed from", previous, "to", current));
   LOG(LINFO, ("Running on thread", std::this_thread::get_id()));
 
-  m_observerInhibited = ((current == routing::SessionState::RouteBuilding)
+  m_routingSessionState = current;
-                         || (current == routing::SessionState::RouteRebuilding));
 
   /*
    * Filter based on session state (see routing_callbacks.hpp for states and transitions).
@@ -806,7 +805,7 @@ void TrafficManager::OnTrafficDataUpdate()
     auto const storageAge = currentTime - m_lastStorageUpdate;
     notifyDrape = (drapeAge >= kDrapeUpdateInterval);
     updateStorage = (storageAge >= kStorageUpdateInterval);
-    if (!m_observerInhibited)
+    if (!IsObserverInhibited())
     {
       /*
        * To avoid resetting the route over and over again while building, inhibit periodic updates

libs/map/traffic_manager.hpp

@@ -533,6 +533,20 @@ private:
     std::for_each(activeMwms.begin(), activeMwms.end(), std::forward<F>(f));
   }
 
+  /**
+   * @brief Whether updates to the observer are currently inhibited.
+   *
+   * Updates are inhibited while a route calculation is in progress. In this state, the observer
+   * receives traffic updates only if the queue has run empty, not if nore locations are waiting
+   * to be decoded.
+   *
+   * Inhibtiting the observer is necessary as traffic updates during route calculation will cause
+   * it to restart from scratch. Once the route has been calculated, updates will trigger a
+   * recalculation, which is much faster (seconds or less).
+   */
+  bool IsObserverInhibited() const { return (m_routingSessionState == routing::SessionState::RouteBuilding)
+      || (m_routingSessionState == routing::SessionState::RouteRebuilding); }
+
   DataSource & m_dataSource;
   CountryInfoGetterFn m_countryInfoGetterFn;
   CountryParentNameGetterFn m_countryParentNameGetterFn;
@@ -546,6 +560,14 @@ private:
    */
   routing::RoutingSession & m_routingSession;
 
+  /**
+   * @brief Cached state of the routing session.
+   *
+   * `m_routingSession` methods which query the state may only be called from the GUI thread,
+   * therefore we are caching this value when we get notified of a change.
+   */
+  routing::SessionState m_routingSessionState = routing::SessionState::NoValidRoute;
+
   df::DrapeEngineSafePtr m_drapeEngine;
   std::atomic<int64_t> m_currentDataVersion;
 
@@ -651,19 +673,6 @@ private:
    */
   std::chrono::time_point<std::chrono::steady_clock> m_lastObserverUpdate;
 
-  /**
-   * @brief Whether updates to the observer are currently inhibited.
-   *
-   * Updates are inhibited while a route calculation is in progress. In this state, the observer
-   * receives traffic updates only if the queue has run empty, not if nore locations are waiting
-   * to be decoded.
-   *
-   * Inhibtiting the observer is necessary as traffic updates during route calculation will cause
-   * it to restart from scratch. Once the route has been calculated, updates will trigger a
-   * recalculation, which is much faster (seconds or less).
-   */
-  bool m_observerInhibited = false;
-
   /**
    * @brief When the cache file was last updated.
    */