VB.NET Two different approaches to generic cross-threaded operations; which is better?

Posted by BASnappl on Stack Overflow See other posts from Stack Overflow or by BASnappl
Published on 2011-02-15T00:01:10Z Indexed on 2011/02/15 23:25 UTC
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VB.NET 2010, .NET 4

Hello,

I recently read about using SynchronizationContext objects to control the execution thread for some code. I have been using a generic subroutine to handle (possibly) cross-thread calls for things like updating UI controls that utilizes Invoke. I'm an amateur and have a hard time understanding the pros and cons of any particular approach. I am looking for some insight on which approach might be preferable and why.

Update: This question is motivated, in part, by statements such as the following from the MSDN page on Control.InvokeRequired.

An even better solution is to use the SynchronizationContext returned by SynchronizationContext rather than a control for cross-thread marshaling.

Method 1:

Public Sub InvokeControl(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of T))
    If Control.InvokeRequired Then
        Control.Invoke(New Action(Of T, Action(Of T))(AddressOf InvokeControl), New Object() {Control, Action})
    Else
        Action(Control)
    End If
End Sub

Method 2:

Public Sub UIAction(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of Control))
    SyncContext.Send(New Threading.SendOrPostCallback(Sub() Action(Control)), Nothing)
End Sub

Where SyncContext is a Threading.SynchronizationContext object defined in the constructor of my UI form:

Public Sub New()
    InitializeComponent()
    SyncContext = WindowsFormsSynchronizationContext.Current
End Sub

Then, if I wanted to update a control (e.g., Label1) on the UI form, I would do:

InvokeControl(Label1, Sub(x) x.Text = "hello")

or

UIAction(Label1, Sub(x) x.Text = "hello")

So, what do y'all think? Is one way preferred or does it depend on the context? If you have the time, verbosity would be appreciated!

Thanks in advance,
Brian

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