fix(stands): fix concurrency issues with stand assignments (#311)

There are potential crash points due to lack of concurrency checking. fix #310
VATSIM-UK · Aug 6, 2021 · 35b9e2a · 35b9e2a
1 parent b309c37
commit 35b9e2a
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Showing 2 changed files with 19 additions and 9 deletions.
diff --git a/src/plugin/stands/StandEventHandler.cpp b/src/plugin/stands/StandEventHandler.cpp
@@ -75,6 +75,7 @@ namespace UKControllerPlugin {
                 [](unsigned char c) { return std::toupper(c); }
             );
 
+            auto mapLock = this->LockStandMap();
             std::string callsign = aircraft->GetCallsign();
             // If no stand is selected, delete the current assignment if there is one
             if (
@@ -121,11 +122,6 @@ namespace UKControllerPlugin {
             }
         }
 
-        size_t StandEventHandler::CountStands(void) const
-        {
-            return this->stands.size();
-        }
-
         size_t StandEventHandler::CountStandAssignments(void) const
         {
             return this->standAssignments.size();
@@ -258,6 +254,7 @@ namespace UKControllerPlugin {
 
             // If a stand is assigned, set the starting text to be the stand identifier
             std::string startingText = "";
+            auto mapLock = this->LockStandMap();
             auto assignedStand = this->standAssignments.find(flightplan.GetCallsign());
             if (
                 assignedStand != this->standAssignments.cend() &&
@@ -294,6 +291,7 @@ namespace UKControllerPlugin {
         */
         void StandEventHandler::SetTagItemData(UKControllerPlugin::Tag::TagData& tagData)
         {
+            auto mapLock = this->LockStandMap();
             if (
                 this->standAssignments.count(tagData.flightPlan.GetCallsign())
             ) {
@@ -373,6 +371,7 @@ namespace UKControllerPlugin {
             EuroScopeCFlightPlanInterface& flightPlan,
             EuroScopeCRadarTargetInterface& radarTarget
         ) {
+            auto mapLock = this->LockStandMap();
             if (!this->standAssignments.count(flightPlan.GetCallsign())) {
                 return;
             }
@@ -413,6 +412,7 @@ namespace UKControllerPlugin {
                     }
 
                     // Delete all existing assignments
+                    auto mapLock = this->LockStandMap();
                     this->standAssignments.clear();
 
                     for (
@@ -444,6 +444,7 @@ namespace UKControllerPlugin {
         */
         void StandEventHandler::ProcessPushEvent(const Push::PushEvent& message)
         {
+            auto mapLock = this->LockStandMap();
             if (message.event == "App\\Events\\StandAssignedEvent") {
                 // If a stand has been assigned, assign it here
                 if (!AssignmentMessageValid(message.data)) {
@@ -455,6 +456,7 @@ namespace UKControllerPlugin {
                     message.data.at("callsign").get<std::string>(),
                     message.data.at("stand_id").get<int>()
                 );
+
                 this->standAssignments[message.data.at("callsign").get<std::string>()] =
                     message.data.at("stand_id").get<int>();
                 LogInfo(
@@ -485,5 +487,10 @@ namespace UKControllerPlugin {
                 }
             };
         }
+
+        std::lock_guard<std::mutex> StandEventHandler::LockStandMap()
+        {
+            return std::lock_guard(this->mapMutex);
+        }
     }  // namespace Stands
 }  // namespace UKControllerPlugin
diff --git a/src/plugin/stands/StandEventHandler.h b/src/plugin/stands/StandEventHandler.h
@@ -12,12 +12,12 @@
 namespace UKControllerPlugin {
     namespace Stands {
         /*
-            A new class
+            Handles events related to stands.
         */
         class StandEventHandler: public UKControllerPlugin::Tag::TagItemInterface,
                                  public Push::PushEventProcessorInterface,
-            public UKControllerPlugin::Flightplan::FlightPlanEventHandlerInterface,
-            public UKControllerPlugin::Integration::ExternalMessageHandlerInterface
+                                 public UKControllerPlugin::Flightplan::FlightPlanEventHandlerInterface,
+                                 public UKControllerPlugin::Integration::ExternalMessageHandlerInterface
         {
             public:
                 StandEventHandler(
@@ -36,7 +36,6 @@ namespace UKControllerPlugin {
                     std::string identifier
                 );
 
-                size_t CountStands(void) const;
                 size_t CountStandAssignments(void) const;
                 void DisplayStandSelectionMenu(
                     UKControllerPlugin::Euroscope::EuroScopeCFlightPlanInterface& flightplan,
@@ -105,6 +104,7 @@ namespace UKControllerPlugin {
                 std::string GetAirfieldForStandAssignment(
                     UKControllerPlugin::Euroscope::EuroScopeCFlightPlanInterface& flightplan
                 );
+                std::lock_guard<std::mutex> LockStandMap();
 
                 // The last airfield that was used to populate the stand menu, used when we receive the callback
                 std::string lastAirfieldUsed = "";
@@ -123,6 +123,9 @@ namespace UKControllerPlugin {
 
                 // The currently assigned stands and who they are assigned to
                 std::map<std::string, int> standAssignments;
+
+                // Locks the stand assignments map to prevent concurrent edits
+                std::mutex mapMutex;
             };
     }  // namespace Stands
 }  // namespace UKControllerPlugin