Using TaskFactory to manage easily dependencies between threads.

With the new TaskFactory class from .Net 4.0 it has become incredibly easy to manage dependencies between multiple tasks.
In below code sample, the TaskFactory receive 6 tasks to execute. Additional logic is added as:
- Task A will only be run when Task B and C are completed.
- Task C will only be run when Task F, E or D is completed.

If you are confused with the ‘=>’ have a look at lambda expression.

using System;
using System.Threading;
using System.Threading.Tasks;

namespace TasksDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            UseTask demoTask = new UseTask();
            Console.ReadKey();
        }
    }

    class UseTask
    {
        public UseTask()
        {
            // Set the TaskFactory - Create and schedule objects
            var tf = new TaskFactory(
                TaskCreationOptions.AttachedToParent,
                TaskContinuationOptions.AttachedToParent);

            var F = tf.StartNew(() => DoSomething(‘F’));
            var E = tf.StartNew(() => DoSomething(‘E’));
            var D = tf.StartNew(() => DoSomething(‘D’));

            // C will be started only when F, E or D has been completed
            var C = tf.ContinueWhenAny(new Task[]{F, E, D}, tasks => DoSomething(‘C’)); 

            var B = tf.StartNew(() => DoSomething(‘B’));

            // A will only happens once B and C are completed.
            var A = tf.ContinueWhenAll(new Task[] {B, C}, tasks => DoSomething(‘A’));
        }

        private void DoSomething(char @char)
        {
            Console.WriteLine(“DoSomething called - {0}”, @char);
            Random rd = new Random();
            Thread.Sleep(rd.Next(1000, 3000));
            Console.WriteLine(“DoSomething called - {0} - DONE”, @char);
        }
    }
}

Isn’t that beautiful?