.NET CF WinCE上的EventArgs线程安全吗？

Question

I'm trying to maintain some horrible VB to get concurrency.

I want to delegate some Maths code to a thread and have it raise an event with EventArgs which contains a structure with the information with which to update a form. In the UI event handler, I'm using BeginInvoke so as not to block the thread because the UI update takes quite a bit of time, but the thread needs to carry on with the next set of Maths.

The previous programmer implemented a timer to call the Maths code and there are a gnats swarm of global variables which represent the results; no way can I implement data locking, it's too big change. The problem with the timer solution is that the Maths code can't run while the UI is being updated (at a slower rate). I've also considered splitting up the UI code across many timer events but this is also quite irksome to achieve to get a balance across the cycles.

Are the EventArgs thread safe ie if the UI starts to use the passed EventArgs and the thread generates another event, OR should the UI clone a copy before control is transferred to the UI thread ?

I've written some test code which looks like this.

Private Observed As UIDelegatePattern.Observed

Private Delegate Sub ProcessDelegate(ByVal sender As Object, ByVal e As UIDelegatePattern.Observed.ProcessEventArgs)

Private Sub Render(ByVal sender As Object, ByVal e As UIDelegatePattern.Observed.ProcessEventArgs)
    If Me.InvokeRequired Then
        Dim d As ProcessDelegate = New ProcessDelegate(AddressOf Render)

        ' invoke on the UI thread asynchronously
        Me.BeginInvoke(d, New Object() {sender, e})
    Else
        ' prevent event overflow by removing the handler before the long rendering activity
        RemoveHandler Observed.EventHandler, AddressOf Render

        ' simulate many controls updates
        For i As Integer = 0 To 1000
            Me.Label1.Text = e.Message
        Next
        Me.Update()
        Me.Refresh()
        Application.DoEvents()

        ' add the handler back in for next time
        AddHandler Observed.EventHandler, AddressOf Render
    End If
End Sub

Answer 1

You've got a lot of information, and possible some other questions implied, in that post. But to be specific, as long as the class that is raising the event creates a new EventArgs on each notification then you are fine and do not need to copy the EventArgs in the event listener.