Treat Forced Update Slightly Differently, ST-Apps#15

Only allow a timed update if we have not just executed a forced update.
Added a mutex as well that will bail out of either update if we are
currently running an update.

PokemonGo-UWP/ViewModels/GameManagerViewModel.cs

@@ -24,6 +24,7 @@
 using Template10.Mvvm;
 using Template10.Services.NavigationService;
 using Universal_Authenticator_v2.Views;
+using System.Threading;
 
 namespace PokemonGo_UWP.ViewModels
 {
@@ -166,6 +167,16 @@ public override async Task OnNavigatingFromAsync(NavigatingEventArgs args)
         /// </summary>
         private ThreadPoolTimer _updateDataTimer;
 
+        /// <summary>
+        /// Mutex to secure the parallel access to the data update
+        /// </summary>
+        private Mutex _updateDataMutex = new Mutex();
+
+        /// <summary>
+        /// If a forced refresh caused an update we should skip the next update
+        /// </summary>
+        private bool _skipNextUpdate = false;
+
         #endregion
 
         #region Bindable Game Vars
@@ -340,8 +351,20 @@ public async Task InitGame(bool hadAuthTokenStored = false)
                     _updateDataTimer = ThreadPoolTimer.CreatePeriodicTimer(t =>
                     {
                         if (_stopUpdatingMap) return;
-                        Logger.Write("Updating map");
-                        UpdateMapData(false);
+                        if (_updateDataMutex.WaitOne(0))
+                        {
+                            if (_skipNextUpdate)
+                            {
+                                _skipNextUpdate = false;
+                            }
+                            else
+                            {
+                                Logger.Write("Updating map");
+                                UpdateMapData(false);
+                            }
+
+                            _updateDataMutex.ReleaseMutex();
+                        }
                     }, TimeSpan.FromSeconds(15));
                 }
             }
@@ -450,6 +473,16 @@ private async void HandleException()
                     });
         }
 
+        private void ForcedUpdateMapData()
+        {
+            if (_updateDataMutex.WaitOne(0))
+            {
+                _skipNextUpdate = true;
+                UpdateMapData(true);
+                _updateDataMutex.ReleaseMutex();
+            }                
+        }
+
         /// <summary>
         ///     Retrieves data for the current position
         /// </summary>
@@ -605,7 +638,7 @@ await Dispatcher.DispatchAsync(() =>
                 {
                     // Encounter failed, probably the Pokemon ran away
                     await new MessageDialog("Pokemon ran away, sorry :(").ShowAsyncQueue();
-                    UpdateMapData();
+                    ForcedUpdateMapData();
                 }
             }, pokemon => true)
             );
@@ -658,7 +691,7 @@ private async Task ThrowPokeball()
                     CurrentCaptureScore = caughtPokemonResponse.Scores;
                     Logger.Write($"We caught {CurrentPokemon.PokemonId}");
                     CatchSuccess?.Invoke(this, null);
-                    UpdateMapData();
+                    ForcedUpdateMapData();
                     UpdateInventory();
                     UpdatePlayerData();
                     break;
@@ -667,15 +700,15 @@ private async Task ThrowPokeball()
                     Logger.Write($"{CurrentPokemon.PokemonId} escaped");
                     CatchEscape?.Invoke(this, null);
                     await new MessageDialog($"{CurrentPokemon.PokemonId} escaped").ShowAsyncQueue();
-                    UpdateMapData();
+                    ForcedUpdateMapData();
                     UpdateInventory();
                     UpdatePlayerData();
                     break;
                 case CatchPokemonResponse.Types.CatchStatus.CatchFlee:
                     Logger.Write($"{CurrentPokemon.PokemonId} fleed");
                     CatchEscape?.Invoke(this, null);
                     await new MessageDialog($"{CurrentPokemon.PokemonId} fleed").ShowAsyncQueue();
-                    UpdateMapData();
+                    ForcedUpdateMapData();
                     UpdateInventory();
                     ReturnToGameScreen.Execute();
                     break;