How to stop the execution of a method after a specific time?

问题

I need to stop the execution of a method if it has not completed within a limited period of time.

To do this work I can use the Thread.Abort method in this way:

void RunWithTimeout(ThreadStart entryPoint, int timeout)
{
    var thread = new Thread(() =>
    {
        try
        {
            entryPoint();
        }
        catch (ThreadAbortException)
        {   }

    }) { IsBackground = true };

    thread.Start();

    if (!thread.Join(timeout))
        thread.Abort();
}

Given that I'm using .NET 3.5, is there a better way?

Edit: following the comments here my entryPoint, but I'm looking for a good way for any entryPoint.

void entryPoint()
{
   // I can't use ReceiveTimeout property
   // there is not a ReceiveTimeout for the Compact Framework
   socket.Receive(...);
}

回答1:

Answer depends on 'the work'. If work is something that can be safely stopped (i.e. not some I/O blocking operation) - use Backgroundworker.CancelAsync(...)

If you do have to cut hard - I'd consider using a Process, in which case the Aborting process is cleaner - and process.WaitForExit(timeout) is your friend.

Suggested TPL is great but unfortunately does not exist in .Net 3.5.

EDIT: You can use Reactive Extensions to follow Jan de Vaan's suggestion.

Here is my 'action timeout' snip - it's mainly here for others to comment on:

    public static bool WaitforExit(this Action act, int timeout)
    {
        var cts = new CancellationTokenSource();
        var task = Task.Factory.StartNew(act, cts.Token);
        if (Task.WaitAny(new[] { task }, TimeSpan.FromMilliseconds(timeout)) < 0)
        { // timeout
            cts.Cancel();
            return false;
        }
        else if (task.Exception != null)
        { // exception
            cts.Cancel();
            throw task.Exception;
        }
        return true;
    }

EDIT: Apparently this isn't exactly what OP wanted. Here's my attempt to devise a 'cancelable' socket receiver:

public static class Ext
{
    public static object RunWithTimeout<T>(Func<T,object> act, int timeout, T obj) where T : IDisposable
    {
        object result = null;
        Thread thread = new Thread(() => { 
            try { result = act(obj); }
            catch {}    // this is where we end after timeout...
        });

        thread.Start();
        if (!thread.Join(timeout))
        {
            obj.Dispose();
            thread.Join();
        }
        return result;
    }       
}

class Test
{
    public void SocketTimeout(int timeout)
    {
        using (var sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp))
        {
            Object res = Ext.RunWithTimeout(EntryPoint, timeout, sock);
        }
    }

    private object EntryPoint(Socket sock)
    {
        var buf = new byte[256];
        sock.Receive(buf);
        return buf;
    }
}

回答2:

Thread.Abort is usually a bad solution. You should use a flag indicating if the operation is canceled and check it inside your entryPoint function.

 class Program
    {
        static void Main(string[] args)
        {
            RunWithTimeout((token) =>
                               {
                                   Thread.Sleep(2000);
                                   if (token.Cancel)
                                   {
                                       Console.WriteLine("Canceled");
                                   }
                               }, 1000);

            Console.ReadLine();
        }

        private class Token
        {
            public bool Cancel { get; set; }
        }

        static void RunWithTimeout(Action<Token> entryPoint, int timeout)
        {

            Token token = new Token();

            var thread = new Thread(() => entryPoint(token)) { IsBackground = true };

            thread.Start();

            if (!thread.Join(timeout))
                token.Cancel = true;
        }
    }

来源：https://stackoverflow.com/questions/13279362/how-to-stop-the-execution-of-a-method-after-a-specific-time

标签

c#-3.0