Nested And Child Task

using System.Windows.Forms;

namespace NestedAndChildTask
{

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnStartNestedTask_Click(object sender, EventArgs e)
        {
            //create an outer task
            //add to it a couple to nested tasks
            //In Lambda expression (() => { }); represent Action Delegate
            Task ParentTask = Task.Factory.StartNew(() =>
            {
                SetText("Parent task started execution", richTextBox1);
                //Start a task within the parentTask. Such Task is therefore a nested task
                Task innerTask1 = Task.Factory.StartNew(() =>
                    {
                        SetText("Child task1 started execution", richTextBox1);
                        //make this child tasks do something, like spinning
                        for (int i = 1; i <= 10; i++)
                        {
                            System.Threading.Thread.SpinWait(150000000);
                        }
                        SetText("Child task1 Comleting.", richTextBox1);
                    });

                //Another child task 2================
                Task innerTask2 = Task.Factory.StartNew(() =>
                {
                    SetText("Child task2 started execution", richTextBox1);
                    //make this child tasks do something, like spinning
                    for (int i = 1; i <= 10; i++)
                    {
                        System.Threading.Thread.SpinWait(150000000);
                    }
                    SetText("Child task2 Comleting.", richTextBox1);
                });


            });
            ParentTask.ContinueWith(task =>
            {
                //At this point in time the parenttask has completed its work
                SetText("Parent task completing.", richTextBox1);
            });


        }
        //=====================Method to set Text=======================
        //1. define a delegate with same signature as the crosss-threading handling
        // method (the SetText method)
        private delegate void RichTextBoxHandler(string s, RichTextBox rtb);
        private void SetText(string s, RichTextBox rtb)
        {
            if (rtb.InvokeRequired)
            {
                //create a delegate object
                RichTextBoxHandler handler = SetText;
                Invoke(handler, s, rtb);
            }
            else
            {
                rtb.AppendText(s + "\n");
                //scroll down
                rtb.ScrollToCaret();
            }
        }

        private void btnStartChildTask_Click(object sender, EventArgs e)
        {
            Task parentTask = Task.Factory.StartNew(() =>
            {
                SetText("Parent task started execution", richTextBox1);
                //Start a task within the parentTask. Such Task is therefore a nested task
                Task childTask1 = Task.Factory.StartNew(() =>
                {
                    SetText("Child task1 started execution", richTextBox1);
                    //make this child tasks do something, like spinning
                    for (int i = 1; i <= 10; i++)
                    {
                        System.Threading.Thread.SpinWait(150000000);
                    }
                    SetText("Child task1 Comleting.", richTextBox1);
                }, TaskCreationOptions.AttachedToParent);

                //Another child task 2================
                Task childTask2 = Task.Factory.StartNew(() =>
                {
                    SetText("Child task2 started execution", richTextBox1);
                    //make this child tasks do something, like spinning
                    for (int i = 1; i <= 10; i++)
                    {
                        System.Threading.Thread.SpinWait(150000000);
                    }
                    SetText("Child task2 Comleting.", richTextBox1);
                }, TaskCreationOptions.AttachedToParent);


            });//This is added for child task.
            parentTask.ContinueWith(task =>
            {
                //At this point in time the parenttask has completed its work
                SetText("Parent task completing.", richTextBox1);
            });

            //Because both inner tasks are attached to parent
            //both tasks are considered child tasks, which implies that the parent
            //WILL NOT terminate until all of its child tasks completes
        }
    }
}
////msdn.microsoft.com/en-us/library/vstudio/dd997417(v=vs.100).aspx

//Lab Assignment
//Define 2 methods similar to the ones we did before 
//GetTotalofOddRandomValues and GetTotalOfEvenRandomValues (may add them as lambda expression)
//Run each method in a separate tasks (task1 and task2)
//Both tasks should run inside a parent task
//The parent task is to get the return values of both task1 and task2, add them and
//display the result
//
//P.S: the methods should not display anyting. you may add a longer loop to makes each
//method run for few seconds