Threads / ExpireSolution problem

Dear all,

I am beginning to play with multi-threading but my understanding of it still being limited, I am facing a problem with the ExpireSolution method. What I am trying to achieve is quite simple: I am triggering a loop on a separate thread so that I can harvest some results, then when a new result is available (in the reality it can take some time) I try to expire the component and to trigger a new solution to update its output.

My problem is that the only way I found to get it to work right now is to use a timer to refresh the component so that it checks if the background task is finished at each interval, but it is a very unpleasant solution since it's forcing the solution of the component everytime. This is why I am trying to use BeginInvoke and Callbacks, as mentioned in older discussions that I found in the forum.

But I suppose I am not doing something correctly, because I still end up triggering solutions when I am not supposed to, and turning everything in ultra-paranoid mode.

I attached a simple vb component that shows the problem.

It's working as follows:

In SolveInstance

If Start Then
 If MyghDoc Is Nothing Then MyghDoc = owner.OnPingDocument
 Dim RunDelegate As AsyncDelegate = AddressOf DoSomeStuff
 RunDelegate.BeginInvoke(AddressOf Callback, Nothing)
 End If
If Reset Then Counter2 = 0
A = Counter2

Outside SolveInstance

Public Delegate Sub AsyncDelegate()
Dim Counter As New Integer
Dim Counter2 As New Integer
Public MyghDoc As GH_Document

Public Sub DoSomeStuff()
 While Counter < 10
  Counter += 1
  Threading.Thread.Sleep(10)
 End While
 Counter = 0
 Counter2 += 1
End Sub

Public Sub Callback(ByVal ar As IAsyncResult)
 If MyghDoc.SolutionState = 0 Then
  owner.ExpireSolution(True)
 Else
  owner.ExpireSolution(False)
 myghdoc.ScheduleSolution(1)
 End If
End Sub

If you start the component and try to pan the canvas, it will force the drawing pipeline to refresh and will trigger the error I am mentioning.

So if some of you have a clue about how to make it thread safe without refreshing all the time... thanks in advance for the help.

T.