给定一个Task实例，我可以告诉它是否已调用ContinueWith吗？

Question

Given a Task instance, how can I tell if ContinueWith has been called on it? I want to know if I'm the last task executing in a chain.

Task task = Task.FromResult();
void SomeMethod(var x) {
   task = task.ContinueWith(previous => {
       if (task.ContinueWith is called) return;
       // do something with x...
   }
}

Answer 1

If you meant multiple continuations. A possible solution may be like this.

class Program
    {
        public class TaskState
        {
            public bool Ended { get; set; }
        }

        static void Main(string[] args)
        {
            var task = Task.FromResult("Stackoverflow");
            var state = new TaskState();
            task.ContinueWith((result, continuationState) =>
            {
                Console.WriteLine("in first");


            }, state).ContinueWith((result, continuationState) =>
            {
                if (!state.Ended)
                    Console.WriteLine("in second");
                state.Ended = true;

            }, state).ContinueWith((result, continuationState) =>
            {
                if (!state.Ended)
                    Console.WriteLine("in third");
                state.Ended = true;

            }, state);
            Console.ReadLine();
        }

    }

Answer 2

You can have a static variable (a dictionary object) declared on the parent and update it with unique keyvalues when your Tasks are triggered. You can monitor this static variable to see if all the other threads has completed the execution or not.