Activating timer from another thread - vb.net

Question

So the purpose of it is to check the connection of the ftp server and if the ftp is up then enable timer1. I've read that threads don't work as synchonized and that is causing the problem. Without the thread it works fine, but the program hangs and stops responding constantly.
How can i activate a timer from another thread?
Maybe invoking and delegating would work? But i don't know how to do that.
Public Function CanPortOpen(ByVal HostName As String, ByVal Port As Integer) As Boolean
Dim TCP As New System.Net.Sockets.TcpClient
Try
TCP.Connect(HostName, Port)
Catch
End Try
If TCP.Connected = True Then
CanPortOpen = True
TCP.Close()
Timer1.Enabled = True
Else
CanPortOpen = False
TCP.Close()
Timer1.Enabled = False
FTPup.Abort()
End If
End Function
Public Sub CheckConnection()
CanPortOpen("HostName", Port)
End Sub
Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
TestFTP = New System.Threading.Thread(AddressOf CheckConnection)
TestFTP.IsBackground = True
TestFTP.Priority = Threading.ThreadPriority.AboveNormal
TestFTP.Start()
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
FTPup = New System.Threading.Thread(AddressOf UploadToFTP)
FTPup.IsBackground = True
FTPup.Priority = Threading.ThreadPriority.AboveNormal
FTPup.Start()
End Sub

Answer 1

I think before you start getting in too deep with threads you should start by looking at the BackgroundWorker component. You can find it on your toolbar in the designer and can drop it on your form. It gives you several events
DoWork - hook up this event with whatever you want done in a background thread
RunWorkerCompleted - hook up this event to run code in the main (UI) thread, triggered when the thread completes. Code here can interact with UI objects as normal.
There are other events that allow you to report progress to your main thread, etc. The purpose of the BackgroundWorker component is to make simple multithreading tasks like this easier.
Documentation is -> here
See -> here for examples of how to pass data from the worker thread to the main thread using EventArgs.
Alternatively, if you just want to run the timer from your thread you can do it like this :
'Declare an appropriate delegate
Delegate Sub dlgTimerEnable(ByVal enable as Boolean)
'the delegate should match the method signature
Private Sub TimerEnable(ByVal enable as Boolean)
Timer1.Enabled = enable
End Sub
and then in your thread procedure
Public Function CanPortOpen(ByVal HostName As String, ByVal Port As Integer) As Boolean
Dim TCP As New System.Net.Sockets.TcpClient
Try
TCP.Connect(HostName, Port)
Catch
End Try
If TCP.Connected = True Then
CanPortOpen = True
TCP.Close()
Me.Invoke(New dlgTimerEnable(AddressOf TimerEnable), New Object() {True})
Else
CanPortOpen = False
TCP.Close()
Me.Invoke(New dlgTimerEnable(AddressOf TimerEnable), New Object() {False})
FTPup.Abort()
End If
End Function
Here Invoke causes the method to be executed on the thread that owns Timer1 (assuming this is a method in your form where Me would refer to your form). The arguments are passed as an object.
You can even do this as a general way to work with any timer, for example :
Delegate Sub dlgTimerEnable(ByRef tmr As Timer, ByVal enable As Boolean)
Private Sub TimerEnable(ByRef tmr As Timer, ByVal enable As Boolean)
tmr.Enabled = enable
End Sub
and then :
Me.Invoke(New dlgTimerEnable(AddressOf TimerEnable), New Object() {Timer1, True})
This makes your delegate general - you can pass it any timer and enable/disable it.