C# ThreadPool wait on result

Question

I want to have a function to something similar:

public static V callAsyncAndWait<V>(Func<V> func)
{
    ThreadPool.QueueUserWorkItem(obj => 
    {
        V v = func.Invoke();                 
    });

    return v;
}

Obviously this code doesn't compile. What I want is to run the Func in another thread and return the result. How can I do that?

Answer 1

I recommend you to use the new .NET 4.0 Task class instead. Here is a tutorial on how to return a result from the execution of Task : http://msdn.microsoft.com/en-us/library/dd537613.aspx

Practically you have a very convenient property called Result , which, upon invocation of the getter, will block until the result is available.

Answer 2

That doesn't make too much sense. If the method is supposed to wait for the task to be finished, then you don't need a separate thread at all.

Something like "call async and notify when done" would make more sense:

void CallAsyncAndNotifyWhenDone<T>(Func<T> func, Action<T> callback)
{
    ThreadPool.QueueUserWorkItem(obj => 
    {
        T result = func();         
        callback(result);
    });
}

Answer 3

You can use async patternt to do it:

public static V callAsyncAndWait<V>(Func<V> func)
{
  var asyncResult = func.BeginInvoke(null, null);

  asyncresult.AsyncWaitHandle.WaitOne();

  return func.EndInvoke(asyncResult);
}