Async Examples

asyncexamples.cs

using System;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Net;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace AysncWinForms
{
    public partial class Form1 : Form
    {
        private TextBox textBox1;

        public Form1()
        {
            InitializeComponent();

            this.ClientSize = new System.Drawing.Size(647, 454);

            CreateTextBox();

            Button b1 = new Button();
            b1.Text = "Wait5scs";
            b1.Click += async (sender, e) =>
                {
                    Stopwatch sw = Stopwatch.StartNew();
                    await Task.Delay(TimeSpan.FromSeconds(5));
                    sw.Stop();
                    textBox1.Text = "Elapsed milliseconds: " + sw.ElapsedMilliseconds;
                };

            this.Controls.Add(b1);

            Button b2 = new Button();
            b2.Text = "CntTo10";
            b2.Location = new Point(0, 50);
            b2.Click += async (sender, e) =>
            {
                var count = await CountToTen();

                textBox1.Text = count.ToString();
            };

            this.Controls.Add(b2);

            Button b3 = new Button();
            b3.Text = "Dwld Bing";
            b3.Location = new Point(0, 100);
            b3.Click += (sender, e) =>
            {
                var webRequest = WebRequest.Create("http://www.google.com");
                webRequest.BeginGetResponse(new AsyncCallback(responseResult =>
                {
                    var response = webRequest.EndGetResponse(responseResult);
                    StreamReader reader = new StreamReader(response.GetResponseStream());
                    textBox1.Text = reader.ReadLine();
                }), null);
            };

            this.Controls.Add(b3);


            Button b4 = new Button();
            b4.Text = "DwldBingAsync";
            b4.Location = new Point(0, 150);
            b4.Click += async(sender, e) =>
            {
                var webRequest = WebRequest.Create("http://www.google.com");
                var response = await webRequest.GetResponseAsync();

                StreamReader reader = new StreamReader(response.GetResponseStream());
                textBox1.Text = reader.ReadLine();
            };

            this.Controls.Add(b4);


            Button b5 = new Button();
            b5.Text = "DeadLock";
            b5.Location = new Point(0, 200);
            b5.Click += (sender, e) =>
            {
                var t = CountToTen();

                t.Wait();

                textBox1.Text = "Delayed 5 seconds";
            };

            this.Controls.Add(b5);


            Button b6 = new Button();
            b6.Text = "NoDeadLock";
            b6.Location = new Point(0, 250);
            b6.Click += (sender, e) =>
            {
                var t = CountToTenWithoutSyncContext();

                t.Wait();

                textBox1.Text = "Delayed 5 seconds";
            };

            this.Controls.Add(b6);

            Button b7 = new Button();
            b7.Text = "AsyncImpl";
            b7.Location = new Point(0, 300);
            b7.Click += async (sender, e) =>
            {
                var str = await this.DownloadStringAsync("http://db.gamefaqs.com/computer/doswin/file/fallout_new_vegas_a.txt");

                textBox1.Text = str;
            };

            this.Controls.Add(b7);
        }

        private void CreateTextBox()
        {
            this.textBox1 = new System.Windows.Forms.TextBox();
            // 
            // textBox1
            // 
            this.textBox1.Dock = System.Windows.Forms.DockStyle.Right;
            this.textBox1.Location = new System.Drawing.Point(311, 0);
            this.textBox1.Multiline = true;
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(336, 454);
            this.textBox1.TabIndex = 0;

            this.Controls.Add(this.textBox1);
        }

        public async Task<int> CountToTenWithoutSyncContext()
        {
            int count = 1;
            for (int i = 0; i < 10; i++)
            {
                var t = Task.Delay(500);
                await t.ConfigureAwait(false);
                count += i;
            }

            return count;
        }

        public async Task<int> CountToTen()
        {
            int count = 1;
            for (int i = 0; i < 10; i++)
            {
                await Task.Delay(500);
                count += i;
            }

            return count;
        }

        public void PrintCountToTen()
        {
            var task = CountToTen();

            System.Runtime.CompilerServices.TaskAwaiter<int> taskAwaiter = task.GetAwaiter();

            taskAwaiter.OnCompleted(() => Console.WriteLine(taskAwaiter.GetResult()));
        }

        private Task<String> DownloadStringAsync(string uri)
        {
            var webclient = new WebClient();

            var downloadTaskCompletionSource = new TaskCompletionSource<String>();
            var downloadTask = downloadTaskCompletionSource.Task;

            webclient.DownloadStringCompleted += (sender, e) =>
                {
                    downloadTaskCompletionSource.SetResult(e.Result);
                };

            webclient.DownloadStringAsync( new Uri(uri));
            return downloadTask;
        }
    }
}