How to call event before Environment.Exit()?

Question

I have a console application in C#. If something goes wrong, I call Environment.Exit() to close my application. I need to disconnect from the server and close some files before the application ends.

In Java, I can implement a shutdown hook and register it via Runtime.getRuntime().addShutdownHook(). How can I achieve the same in C#?

Krieg

Answer 1

You can attach an event handler to the current application domain's ProcessExit event:

using System;
class Program
{
    static void Main(string[] args)
    {
        AppDomain.CurrentDomain.ProcessExit += (s, e) => Console.WriteLine("Process exiting");
        Environment.Exit(0);
    }
}

Flanigan

Answer 2

Hook AppDomain events:

private static void Main(string[] args)
{
    var domain = AppDomain.CurrentDomain;
    domain.UnhandledException += new UnhandledExceptionEventHandler(MyHandler);
    domain.ProcessExit += new EventHandler(domain_ProcessExit);
    domain.DomainUnload += new EventHandler(domain_DomainUnload);
}
static void MyHandler(object sender, UnhandledExceptionEventArgs args)
{
    Exception e = (Exception)args.ExceptionObject;
    Console.WriteLine("MyHandler caught: " + e.Message);
}

static void domain_ProcessExit(object sender, EventArgs e)
{
}
static void domain_DomainUnload(object sender, EventArgs e)
{
}

Bilek

Answer 3

I'd recommend wrapping the call to Environment.Exit() in your own method and using that throughout. Something like this:

internal static void MyExit(int exitCode){
    // disconnect from network streams
    // ensure file connections are disposed
    // etc.
    Environment.Exit(exitCode);
}

Insanity

-1: This significantly increases Coupling when there are other easy ways to make things work without this: en.wikipedia.org/wiki/Coupling_(computer_science) – Villainage

how would it increase coupling? The question is asking about how to tackle this within a Console application, so calling Environment.Exit would be a valid action. Granted using the events would be easier, but they are going against the AppDomain, not the process. – Insanity

If you need to do some cleanup for resource A when it's done being used, keep the cleanup local to A. Don't require A, B, C, and D to make special accomodations for it. – Villainage

One case where this may not make the cut is in case of unhandled exceptions which can lead to application exit, in which case MyExit wont be called. Still a valid answer. Dont think this deserve a downvote – Bifocals