Question

In C#, how do you make a program only process one thing at a time? I’ve been working on a patching system, and I think I have the coding all correct but can’t test it because a lot of the functions are trying to process all at once when they need to be processing in an order. The program doesn’t even let the display shown up before it starts trying to process everything. Because none of them return a value other then the main function all the functions are set to void. I thought about maybe using a return value inside of a loop to make sure the program is finished with that step first before moving on but it still leaves the problem of the program not even showing up until everything is done processing which its suppose to show the progress of everything. Any suggestions of tips?

Edit: I don’t know what to post in the code, so im posting all the main functions:

    public void DSP_Load(object sender, EventArgs e)
    {
        if (v1 >= v2)
        {
            File_Progress_Title.Text = "100%";
            Update_Status.Text = "Divine Shadows is currently up to date.";
            Application.DoEvents();
            Process.Start("Divine Shadows.exe");
            Close();
        }
        else
        {
            Update_Status.Text = "Checking For Updates...";
            Application.DoEvents();

            if (!Directory.Exists(tempFilePath))
            {
                Directory.CreateDirectory(tempFilePath);
            }

            using (SqlCon = new MySqlConnection(connString))
            {
                SqlCon.Open();
                string command = "SELECT * FROM version where version > '" + v1 + "' ORDER BY version LIMIT 1";
                MySqlCommand GetLatestVersion = new MySqlCommand(command, SqlCon);

                using (MySqlDataReader DR = GetLatestVersion.ExecuteReader())
                {
                    while(DR.Read())
                    {
                        do
                        {
                            string LatestVersion = Convert.ToString(DR.GetValue(1));
                            string WebURL = Convert.ToString(DR.GetValue(2));
                            update.DownloadFileAsync(new Uri(WebURL), tempFilePath + "patch" + LatestVersion + ".zip");
                            update.DownloadProgressChanged += new DownloadProgressChangedEventHandler(download);
                            update.DownloadFileCompleted += new AsyncCompletedEventHandler(extration);
                            Application.Restart();
                        }
                        while (v1 < v2);
                        Process.Start("Divine Shadows.exe");
                        Close();
                    }
                }
            }
        }
    }

    public void download(object sender, DownloadProgressChangedEventArgs e)
    {
        if (v1 >= v2)
        {
            File_Progress_Title.Text = "100%";
            Update_Status.Text = "Divine Shadows is currently up to date.";
            Application.DoEvents();
            Process.Start("Divine Shadows.exe");
            Close();
        }
        else
        {
            Update_Status.Text = "Downloading Updates...";
            Application.DoEvents();
            File_Progress_Display.Value = e.ProgressPercentage;
            File_Progress_Title.Text = Convert.ToString(e.ProgressPercentage) + "%";
        }
    }

    public void extration(object sender, AsyncCompletedEventArgs e)
    {
        if (v1 >= v2)
        {
            File_Progress_Title.Text = "100%";
            Update_Status.Text = "Divine Shadows is currently up to date.";
            Application.DoEvents();
            Process.Start("Divine Shadows.exe");
            Close();
        }
        else
        {
            Update_Status.Text = "Installing Updates, Please Wait...";
            Application.DoEvents();
            UnzipFile(extactFile, extractLocation);
        }
    }

    public static void UnzipFile(string extactFile, string extractLocation)
    {
        try
        {
            FastZip fastZip = new FastZip();
            fastZip.CreateEmptyDirectories = false;
            fastZip.ExtractZip(extactFile, extractLocation, FastZip.Overwrite.Always, null, null, null, false); 
        }
        catch (Exception ex)
        {
            throw new Exception("Error unzipping file \"" + extactFile + "\"", ex);
        }
        File.Delete(extactFile);
    }

Answer 1

Your problem is not WebClient() specific, its about how your application is working with threads.

In general, winforms applications have one GUI Thread. This thread is used to executed your methods and also updating the user interface. If you start a long term process, the gui thread gets locked till the operation is finished. Thats the reason why your display is not shown.

You can solve that problem by implementing the BackgroundWorker. On that website you can also find an example how to implement it. Let the BackgroundWorker do your patching process and use events inside the BackgroundWorker.RunWorkerAsync() method to update your GUI.