csharp-trap-ctrl-c.md

csharp trap ctrl+c

Notes:

• if pass cts.Token to Task.Delay then the operation "listen" for cancellation and interrupt delay immediately if ctrl+c issued ( or SIGINT )
• there is the need to try/catch the OperationCanceledException when passing cts.Token in order to handle the case of interruption
• for example the following code will generate an exception if insert cts.Token on the Task.Run or Task.Wait methods but for the purpose we don't need to interrupt the task itself neither its waiting because the inner loop closes regularly thanks to while (!cts.IsCancellationRequested)

namespace example;

class Program
{
    static void Main(string[] args)
    {
        System.Console.WriteLine($"start");

        var cts = new CancellationTokenSource();

        Console.CancelKeyPress += (a, b) =>
        {
            b.Cancel = true;
            cts.Cancel();
            System.Console.WriteLine($"application shutdown requested");
        };
        
        Task.Run(async () =>
        {
            while (!cts.IsCancellationRequested)
            {
                try
                {
                    await Task.Delay(1000, cts.Token);
                }
                catch (OperationCanceledException)
                {
                }
            }
        }).Wait();

        System.Console.WriteLine($"application ended");
    }
}