Merge pull request #5 from jhickson/stoprace

Fixed a race condition when stopping very soon after starting.

Author: Jos Hickson

Winton.Extensions.Threading.Actor/Internal/StateMachine/ActiveActorState.cs

@@ -64,6 +64,8 @@ protected override void StopImpl()
 
         protected override void EnterImpl()
         {
+            Context.StartCompletionSource.SetResult(true);
+
             foreach (var task in Context.InitialWorkQueue)
             {
                 Context.StartTask(task);

Winton.Extensions.Threading.Actor/Internal/StateMachine/ActorContext.cs

@@ -25,6 +25,8 @@ public ActorContext(IActorTaskFactory actorTaskFactory)
 
         public List<Task> InitialWorkQueue { get; } = new List<Task>();
 
+        public List<Task> InitialWorkToBeCancelledQueue { get; } = new List<Task>();
+
         public IActorTaskFactory ActorTaskFactory { get; }
 
         public ActorStartWork StartWork

Winton.Extensions.Threading.Actor/Internal/StateMachine/InitialActorState.cs

@@ -19,7 +19,6 @@ protected override void StartImpl()
             }
             else
             {
-                Context.StartCompletionSource.SetResult(true);
                 Context.SetState<ActiveActorState>();
             }
         }

Winton.Extensions.Threading.Actor/Internal/StateMachine/StartingActorState.cs

@@ -34,7 +34,6 @@ protected override void EnterImpl()
                          {
                              await task.ConfigureAwait(false);
 
-                             Context.StartCompletionSource.SetResult(true);
                              Context.SetState<ActiveActorState>();
 
                              if (ReceivedStopSignal)
@@ -62,7 +61,14 @@ protected override void EnterImpl()
 
         protected override void ScheduleImpl(Task task)
         {
-            Context.InitialWorkQueue.Add(task);
+            if (!ReceivedStopSignal)
+            {
+                Context.InitialWorkQueue.Add(task);
+            }
+            else
+            {
+                Context.InitialWorkToBeCancelledQueue.Add(task);
+            }
         }
 
         private bool ReceivedStopSignal { get; set; } = false;

Winton.Extensions.Threading.Actor/Internal/StateMachine/StoppedActorState.cs

@@ -1,3 +1,4 @@
+using System.Linq;
 using System.Threading.Tasks;
 
 namespace Winton.Extensions.Threading.Actor.Internal.StateMachine
@@ -24,12 +25,13 @@ protected override void StopImpl()
 
         protected override void EnterImpl()
         {
-            foreach (var task in Context.InitialWorkQueue)
+            foreach (var task in Context.InitialWorkQueue.Concat(Context.InitialWorkToBeCancelledQueue))
             {
                 task.Cancel();
             }
 
             Context.InitialWorkQueue.Clear();
+            Context.InitialWorkToBeCancelledQueue.Clear();
         }
     }
 }