How to kill an asynchronous delegate?

[Stewart]

Hey Group,

Hoping someone can help me out. I have some code which starts up some
asynchronous code using a delegate. The code is below. Basically my
main code (not shown) calls ServerThreadSta rt.StartServer to start the
server running asynchronously. This works fine. Shouldn't be any
problems here.

My question is how can I get my code to kill this code running
asynchronously? There is a dlgtServer.Remo ve(Delegate, Delegate)
command but there seems to be little of value in MSDN to help you
determine the two parameters.

Hope you can help,

Stewart



Friend Delegate Sub ListenForConnec tionDelegate(By Val PortNo As Int16)

Friend Class ServerThreadSta rter

Friend Shared Sub StartServer(ByV al PortNo As Int16)
Dim ar As IAsyncResult
Dim dlgtServer As New ListenForConnec tionDelegate(Ad dressOf
ServerThread.Li stenForConnecti on)

ar = dlgtServer.Begi nInvoke(PortNo, AddressOf
CallbackFromSer verThread, dlgtServer)

ar = Nothing
dlgtServer = Nothing
End Sub

Private Shared Sub CallbackFromSer verThread(ByVal ar As
IAsyncResult)
' Retrieve the delegate
Dim dlgt As ListenForConnec tionDelegate = CType(ar.AsyncS tate,
ListenForConnec tionDelegate)
' Call EndInvoke
dlgt.EndInvoke( ar)
dlgt = Nothing
End Sub
End Class

Friend Class ServerThread
Friend Shared Sub ListenForConnec tion(ByVal PortNo As Int16)
...
End Sub
End Class

[cecil@ceciltech.com]

Re: How to kill an asynchronous delegate?

Stewart,[color=blue]
>From the looks of what you are doing you would be better off using[/color]
the Thread class to spawn your worker thread. By using a delegate's
BeginInvoke method you are making use of a thread from the thread pool.
This method of multithreading is optimized for shorter running tasks
and has no built in way to allow you to kill the thread. I am sure it
could be done, but it would be a hack. If you use the Thread class you
have much greater control including the ability to kill the thread.
The method you start the thread with can not take any methods so remove
portno from the args of your listen method and make it a private field
of the class that is set in the constructor and make the listen method
an instance method instead of shared.

Hope this helps

Cecil Howell MCSD, MCAD.Net, MCT


Stewart wrote:[color=blue]
> Hey Group,
>
> Hoping someone can help me out. I have some code which starts up[/color]
some[color=blue]
> asynchronous code using a delegate. The code is below. Basically my
> main code (not shown) calls ServerThreadSta rt.StartServer to start[/color]
the[color=blue]
> server running asynchronously. This works fine. Shouldn't be any
> problems here.
>
> My question is how can I get my code to kill this code running
> asynchronously? There is a dlgtServer.Remo ve(Delegate, Delegate)
> command but there seems to be little of value in MSDN to help you
> determine the two parameters.
>
> Hope you can help,
>
> Stewart
>
>
>
> Friend Delegate Sub ListenForConnec tionDelegate(By Val PortNo As[/color]
Int16)[color=blue]
>
> Friend Class ServerThreadSta rter
>
> Friend Shared Sub StartServer(ByV al PortNo As Int16)
> Dim ar As IAsyncResult
> Dim dlgtServer As New ListenForConnec tionDelegate(Ad dressOf
> ServerThread.Li stenForConnecti on)
>
> ar = dlgtServer.Begi nInvoke(PortNo, AddressOf
> CallbackFromSer verThread, dlgtServer)
>
> ar = Nothing
> dlgtServer = Nothing
> End Sub
>
> Private Shared Sub CallbackFromSer verThread(ByVal ar As
> IAsyncResult)
> ' Retrieve the delegate
> Dim dlgt As ListenForConnec tionDelegate =[/color]
CType(ar.AsyncS tate,[color=blue]
> ListenForConnec tionDelegate)
> ' Call EndInvoke
> dlgt.EndInvoke( ar)
> dlgt = Nothing
> End Sub
> End Class
>
> Friend Class ServerThread
> Friend Shared Sub ListenForConnec tion(ByVal PortNo As Int16)
> ...
> End Sub
> End Class[/color]

[windsurfing_stew@yahoo.com.au]

Re: How to kill an asynchronous delegate?

Thanks for your help. I've updated this code to work with the
Threading object rather than using delegates. Notice I've added a
StopServer method.

Friend Class ServerThreadSta rter

Private Shared thrd As Thread

Friend Shared Sub StartServer(ByV al PortNo As Int16)
Dim svr As ServerThread

svr.PortNo = 8989
If thrd Is Nothing Then
thrd = New Thread(AddressO f svr.ListenForCo nnection)
thrd.Start()
End If
End Sub

Friend Shared Sub StopServer()
If Not thrd Is Nothing Then
thrd.Abort()
thrd.Join()
End If
End Sub

End Class

[Herfried K. Wagner [MVP]]

Re: How to kill an asynchronous delegate?

<windsurfing_st ew@yahoo.com.au > schrieb[color=blue]
> thrd.Abort()[/color]

If you have control over the thread's implementation/work:

How To Stop a Thread in .NET (and Why 'Thread.Abort' is Evil)
<URL:http://www.interact-sw.co.uk/iangblog/2004/11/12/cancellation>

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>