Re: Thread termination

From: Jon Skeet [C# MVP] (skeet_at_pobox.com)
Date: 02/28/04 

Date: Sat, 28 Feb 2004 20:57:12 -0000

ice88 <ian_edwards@ntlworld.com> wrote:
> I would like to execute some code when a thread terminates, in the
> context of that thread - I guess similar to an ExitThread handler - is
> it possible in a C# .NET application?
>
> I can see a way to execute code when a thread is thrown away - by
> having per-thread static attributes that are themselves objects, when
> the thread object associated with that static value is garbage
> collected, the destructor for the object is driven - but that happens
> on another thread, I need the execution to happen on the thread that
> is ending (because I'm going to make a call to unmanaged code to clear
> up some things which the unmanaged code has associated with the
> thread)...
>
> I would like to believe that the framework does provide for a 'thread
> is about to be deleted' class, which implements some interface - but I
> cannot find it - unless IDisposable does it?

It strikes me that the easiest way of doing this in a general way would
be something like:

public delegate void ThreadFinish();

public class ThreadStarterWithFinish
{
    public event ThreadFinish Finish;

    ThreadStart starter;

    public ThreadStarterWithFinish (ThreadStart starter)
    {
        this.starter = starter;
    }

    public void Run()
    {
        try
        {
             starter();
        }
        finally
        {
             if (Finish != null)
             {
                 Finish();
             }
        }
    }
    
    public void StartThread()
    {
        new Thread (new ThreadStart(Run)).Start();
    }
}

Here's a test program to demonstrate its use:

public class Test
{
    static void Main()
    {
        ThreadStarterWithFinish tswf = new
            ThreadStarterWithFinish (new ThreadStart(Normal));
        
        tswf.Finish += new ThreadFinish (OnFinish);
        
        tswf.StartThread();
    }
    
    static void Normal()
    {
        Console.WriteLine ("Normal");
    }
      
    static void OnFinish()
    {
        Console.WriteLine ("OnFinish");
    }
}

For a non-general solution, just put a try/finally block in the
appropriate ThreadStart-compatible method. 

-- 
Jon Skeet - <skeet@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

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