Handling CancelKeyPress using a CancellationToken

You sometimes need to detect when a console application is closing to perform some cleanup. Console.CancelKeyPress allows registering a callback when a user press Ctrl+C or Ctrl+Break. This event can prevent the application from closing, so you can take a few seconds to perform the cleanup before actually terminating the application. The idea of this post is to use Console.CancelKeyPress to create a CancellationToken that can be used to cancel current asynchronous operations.

public class Program
{
    public static async Task Main(string[] args)
    {
        using var cts = new CancellationTokenSource();
        Console.CancelKeyPress += (sender, e) =>
        {
            // We'll stop the process manually by using the CancellationToken
            e.Cancel = true;

            // Change the state of the CancellationToken to "Canceled"
            // - Set the IsCancellationRequested property to true
            // - Call the registered callbacks
            cts.Cancel();
        };

        await MainAsync(args, cts.Token);
    }

    private static async Task MainAsync(string[] args, CancellationToken cancellationToken)
    {
        try
        {
            // code using the cancellation token
            Console.WriteLine("Waiting");
            await Task.Delay(10_000, cancellationToken);
        }
        catch (OperationCanceledException)
        {
            Console.WriteLine("Operation canceled");
        }
    }
}

If you need to handle more cases than the CancelKeyPress, you can check this post about detecting console closing in .NET. It uses the SetConsoleCtrlHandler method to detect when the console is closing.

Do you have a question or a suggestion about this post? Contact me!