Stop hanging synchronous method

Question

There is a method HTTP_actions.put_import() in XenAPI, which is synchronous and it supports cancellation via its delegate.

I have the following method:

private void UploadImage(.., Func<bool> isTaskCancelled)
{
    try
    {
        HTTP_actions.put_import(
            cancellingDelegate: () => isTaskCancelled(),
            ...);
    }
    catch (HTTP.CancelledException exception)
    {
    }
}

It so happens that in some cases this method HTTP_actions.put_import hangs and doesn't react to isTaskCancelled(). In that case the whole application also hangs.

I can run this method in a separate thread and kill it forcefully once I receive cancellation signal, but this method doesn't always hang and sometimes I want to gracefully cancel this method. Only when this method is really hanging, I want to kill it myself.

What is the best way to handle such situation?

Answer 1

Wrote blog post for below : http://pranayamr.blogspot.in/2017/12/abortcancel-task.html

Tried lot of solution since last 2 hr for you and I come up with below working solution , please have try it out

class Program
{
   //capture request running that , which need to be cancel in case
   // it take more time 
    static Thread threadToCancel = null;
    static async Task<string> DoWork(CancellationToken token)
    {
        var tcs = new TaskCompletionSource<string>();
        //enable this for your use
    //await Task.Factory.StartNew(() =>
    //{
    //    //Capture the thread
    //    threadToCancel = Thread.CurrentThread;
    //    HTTP_actions.put_import(...); 
    //});
    //tcs.SetResult("Completed");
    //return tcs.Task.Result;

    //comment this whole this is just used for testing 
        await Task.Factory.StartNew(() =>
        {
            //Capture the thread
            threadToCancel = Thread.CurrentThread;

            //Simulate work (usually from 3rd party code)
            for (int i = 0; i < 100000; i++)
            {
                Console.WriteLine($"value {i}");
            }

            Console.WriteLine("Task finished!");
        });

        tcs.SetResult("Completed");
        return tcs.Task.Result;
    }


    public static void Main()
    {
        var source = new CancellationTokenSource();
        CancellationToken token = source.Token;
        DoWork(token);
        Task.Factory.StartNew(()=>
        {
            while(true)
            {
                if (token.IsCancellationRequested && threadToCancel!=null)
                {
                    threadToCancel.Abort();
                    Console.WriteLine("Thread aborted");
                }
            }
        });
        ///here 1000 can be replace by miliseconds after which you want to 
        // abort thread which calling your long running method 
        source.CancelAfter(1000);
        Console.ReadLine();   
    }
}