Small fixes improving threads synchronization.

Author: peetery

Logic/LogicAPI.cs

@@ -2,13 +2,14 @@
 using System;
 using System.Collections.ObjectModel;
 using System.Numerics;
+using System.Threading;
 
 namespace Logic
 {
     public class LogicAPI : LogicAbstractAPI
     {
         private readonly DataAPI _dataAPI;
-        private CancellationToken _cancellationToken;
+        private CancellationTokenSource _cancellationTokenSource;
         private List<Task> _tasks = new List<Task>();
 
         public override Table table { get; }
@@ -23,44 +24,39 @@ public LogicAPI()
 
         public override void RunSimulation()
         {
-            _cancellationToken = CancellationToken.None;
+            _cancellationTokenSource = new CancellationTokenSource();
             float timeTravel = 0.01f;
 
             foreach (BallLogic ball in balls)
             {
-                Task task = Task.Run(() =>
+                Task task = Task.Run(async () =>
                 {
                     while (true)
                     {
-                        // Thread.Sleep(TimeSpan.FromSeconds(timeTravel));
-                        try
-                        {
-                            _cancellationToken.ThrowIfCancellationRequested();
-                        }
-                        catch (OperationCanceledException)
-                        {
+                        await Task.Delay(TimeSpan.FromSeconds(timeTravel), _cancellationTokenSource.Token);
+                        if (_cancellationTokenSource.Token.IsCancellationRequested)
                             break;
-                        }
                         ball.setPosition();
                     }
-                });
+                }, _cancellationTokenSource.Token);
                 _tasks.Add(task);
             }
         }
 
         public override void StopSimulation()
         {
-            _cancellationToken = new CancellationToken(true);
+            _cancellationTokenSource?.Cancel();
 
-            foreach (Task task in _tasks)
+            try
             {
-                task.Wait();
+                Task.WhenAll(_tasks).Wait();
             }
+            catch (AggregateException) { }
 
             _tasks.Clear();
             balls.Clear();
         }
-        
+
         public override BallLogic createBall(int radius, Vector2 position)
         {
             Vector2 basicVelocity = new Vector2((float)0.01, (float)0.01);

ViewModel/MainWindowViewModel.cs

@@ -63,10 +63,10 @@ public int viewWidth
             get { return _width; }
         }
 
-        private void CreateHandler()
+        private async void CreateHandler()
         {
             ballsGroup = _modelLayer.createBalls(_ballsAmount, 25);
-            _modelLayer.StartSimulation();
+            await Task.Run(() => _modelLayer.StartSimulation());
         }
 
         private void StopHandler()