wait for database files to be released before trying to write in them

LocalServices/Data/CatastrophicPerformancesDatabase.cs

@@ -76,38 +76,38 @@ namespace LocalEndpoint.Data
             return usersData[user].Rates[recipe];
         }
 
-        public async void InsertInUserList(Guid userId, Guid recipeId, uint persAmount)
+        public void InsertInUserList(Guid userId, Guid recipeId, uint persAmount)
         {
             usersData[userId].RecipesList[recipeId] = persAmount;
             Save(USERS_FILENAME, USERS_SERIALIZER, usersData);
         }
 
-        public async void RemoveFromUserList(Guid userId, Guid recipeId)
+        public void RemoveFromUserList(Guid userId, Guid recipeId)
         {
             usersData[userId].RecipesList.Remove(recipeId);
             Save(USERS_FILENAME, USERS_SERIALIZER, usersData);
         }
 
 
-        public async void InsertRecipe(Recipe recipe)
+        public void InsertRecipe(Recipe recipe)
         {
             recipesData[recipe.Info.Id] = new RecipeData(recipe.Info, recipe.Owner.Id, recipe.Ingredients, recipe.Steps);
             Save(RECIPES_FILENAME, RECIPES_SERIALIZER, recipesData);
         }
 
-        public async void InsertUser(User user)
+        public void InsertUser(User user)
         {
             usersData[user.Id] = new UserData(user, new Dictionary<Guid, RecipeRate>(), new Dictionary<Guid, uint>());
             Save(USERS_FILENAME, USERS_SERIALIZER, usersData);
         }
 
-        public async void InsertRate(Guid userId, Guid recipeId, RecipeRate rate)
+        public void InsertRate(Guid userId, Guid recipeId, RecipeRate rate)
         {
             usersData[userId].Rates[recipeId] = rate;
             Save(USERS_FILENAME, USERS_SERIALIZER, usersData);
         }
 
-        public async void RemoveRecipe(Guid id)
+        public void RemoveRecipe(Guid id)
         {
             recipesData.Remove(id);
             Save(RECIPES_FILENAME, RECIPES_SERIALIZER, recipesData);
@@ -154,8 +154,35 @@ namespace LocalEndpoint.Data
         private async void Save<K, T>(string fileName, DataContractSerializer serializer, Dictionary<K, T> dict)
         {
             string json = JsonSerializer.Serialize(dict);
-            File.WriteAllText(dbPath + "/" + fileName, json);
+            using (var stream = WaitForFile(fileName, FileMode.Open, FileAccess.Write, FileShare.Write))
+            {
+                var bytes = Encoding.ASCII.GetBytes(json);
+                await stream.WriteAsync(bytes, 0, bytes.Length);
+            }
+        }
+
+        // This is a workaround function to wait for a file to be released before opening it.
+        // This was to fix the Save method that used to throw sometimes as the file were oftenly being scanned by the androids' antivirus.
+        // Simply wait until the file is released and return it. This function will never return until
+        private static FileStream WaitForFile(string fullPath, FileMode mode, FileAccess access, FileShare share)
+        {
+            for (int attempt = 0 ; attempt < 20; attempt++) //20 attempts equals to 2 seconds of wait
+            {
+                FileStream? fs = null;
+                try
+                {
+                    fs = new FileStream(fullPath, mode, access, share);
+                    return fs;
+                }
+                catch (IOException)
+                {
+                    if (fs != null)
+                        fs.Dispose();
+
+                    Thread.Sleep(100);
+                }
+            }
+            throw new TimeoutException("Could not access file '" + fullPath + "', maximum attempts reached.");
         }
-
     }
 }