How to start a long running process in a separate thread

Question

ok here we go last part almost done! one error to go hmmmmm. This is using the suggestion and is complaining about delegates i think.

using System;


    public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        pictureBox2.Visible = false;    
    }

    private void button1_Click(object sender, EventArgs e)
    {

        Task t = new Task(() => GetsalesFigures(accCollection.Text));

        t.Start();  
    }

    private void SetPictureBoxVisibility(bool IsVisible)
    {
        if (pictureBox2.InvokeRequired)
        {
            pictureBox2.Invoke(new Action<bool>(SetPictureBoxVisibility), new Object[] { IsVisible });
        }
        else
        {
            pictureBox2.Visible = IsVisible;
        }
    }

    private void SetCheckBoxValue(bool IsChecked)
    {
        if (checkBox1.InvokeRequired)
        {
            pictureBox2.Invoke(new Action<bool>(SetCheckBoxValue), new Object[] { IsChecked });
        }
        else
        {
            checkBox1.Checked = IsChecked;
        }
    }

    private void AddItem(string value)
    {
        if (accCollection.InvokeRequired)
        {
            accCollection.Invoke(new Action<string>(AddItem), new Object[] { value });
        }
        else
        {
            accCollection.Items.Add(value);
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        AutofillAccounts();
    }


    private void GetsalesFigures(string Acct)
    {
        try
        {
            string myConn = "Server=af" +
                            "Database=sdfta;" +
                            "uid=busdf4;" +
                            "pwd=drsdft;" +
                            "Connect Tisdf=120;";

            string acct;// test using 1560
            SqlConnection conn = new SqlConnection(myConn);
            SqlCommand Pareto = new SqlCommand();
            BindingSource bindme = new BindingSource();
            SqlDataAdapter adapt1 = new SqlDataAdapter(Pareto);
            DataSet dataSet1 = new DataSet();
            DataTable table1 = new DataTable();

           //CREATE THE THREAD

            //acct = accCollection.Text;
            acct = Acct;

            string fromDate = this.dateTimePicker1.Value.ToString("MM/dd/yyyy");
            string tooDate = this.dateTimePicker2.Value.ToString("MM/dd/yyyy");

            Pareto.Connection = conn;
            Pareto.CommandType = CommandType.StoredProcedure;
            Pareto.CommandText = "dbo.GetSalesParetotemp";
            Pareto.CommandTimeout = 120;

            Pareto.Parameters.AddWithValue("@acct", acct);
            Pareto.Parameters.AddWithValue("@from", fromDate);
            Pareto.Parameters.AddWithValue("@too", tooDate);


            //pictureBox2.Visible = true;
            //checkBox1.Checked = true;
            SetCheckBoxValue(true);
            SetPictureBoxVisibility(true);

            adapt1.Fill(dataSet1, "Pareto");
            //checkBox1.Checked = false;
            //pictureBox2.Visible = false;
            SetCheckBoxValue(false);
            SetPictureBoxVisibility(true);

            this.dataGridView1.AutoGenerateColumns = true;
            this.dataGridView1.DataSource = dataSet1;
            this.dataGridView1.DataMember = "Pareto";

            dataGridView1.AutoResizeColumns(
                DataGridViewAutoSizeColumnsMode.AllCells);

            SetPictureBoxVisibility(true);
            acct = Acct;

        }
        catch (Exception execc)
        {
            MessageBox.Show("Whoops! Seems we couldnt connect to the server!"
                            + " information:\n\n" + execc.Message + execc.StackTrace,
                            "Fatal Error", MessageBoxButtons.OK, MessageBoxIcon.Stop);
        } 
    }

    private void AutofillAccounts()
    {
        //get customers list and fill combo box on form load.
        try
        {
            string myConn1 = "Server=sdf33;" +
                                "Database=sdft;" +
                                "uid=bdf4;" +
                                "pwd=ddft;" +
                                "Connect Timeout=6000;";
            SqlConnection conn1 = new SqlConnection(myConn1);
            conn1.Open();
            SqlCommand accountFill = new SqlCommand("SELECT keycode FROM dbo.Customer", conn1);

            SqlDataReader readacc = accountFill.ExecuteReader();

            while (readacc.Read())
            {
                AddItem(readacc.GetString(0).ToString());
            }
            conn1.Close();
        }
        catch(Exception exc1)
        {
            MessageBox.Show("Whoops! Seems we couldnt connect to the server!"
                            + " information:\n\n" + exc1.Message + exc1.StackTrace,
                            "Fatal Error", MessageBoxButtons.OK, MessageBoxIcon.Stop);
        }
    }
}

}

not sure where the changes should be made, shouldnt it be in the account method now?

Answer 1

Fixed some minor spelling errors, didn't have a compiler at hand back then. To your last error: Just provide the accCollection.Text as parameter to your method. See the updated button1_Click() and GetsalesFigures(String Acct). This is how my Partial Class : Form looks like

  public Form1()
{
  InitializeComponent();
  pictureBox2.Visible = false;
}
private void Form1_Load(object sender, EventArgs e) 
{ 
  AutofillAccounts(); 
}  
private void button1_Click(object sender, EventArgs e)
{
  checkBox1.Checked = true;
  string acct = accCollection.Text;
  Task t = new Task(() => GetsalesFigures(acct)); 
  t.Start();
}
private void GetsalesFigures(String Acct)
{
  // (...)
  //pictureBox2.Visible = true; use SetPictureBoxVisibility
  SetPictureBoxVisibility(true);
  //checkBox1.Checked = true; use SetCheckBoxValue
  SetCheckBoxValue(true);
  // (...)
  SetCheckBoxValue(false);
  SetPictureBoxVisibility(false); 
  // (...)
  acct = Acct;
 // (...)
 SetDataGrid(true, dataSet1, "Pareto", DataGridViewAutoSizeColumnsMode.AllCells);
}
private void AutofillAccounts()
{
   // (...)
   while (readacc.Read())             
    {                 
      AddItem(readacc.GetString(0).ToString());             
    }
}
private void SetCheckBoxValue(bool IsChecked)
{
  if (checkBox1.InvokeRequired)
  {
    pictureBox2.Invoke(new Action<bool>(SetCheckBoxValue), new Object[] { IsChecked });
  }
  else
  {
    checkBox1.Checked = IsChecked;
  }
}
private void SetPictureBoxVisibility(bool IsVisible)
{
  if (pictureBox2.InvokeRequired)
  {
    pictureBox2.Invoke(new Action<bool>(SetPictureBoxVisibility), new Object[] { IsVisible });
  }
  else
  {
    pictureBox2.Visible = IsVisible;
  }
}
// Your latest comment
 private void AddItem(string value)
 {
  if (accCollection.InvokeRequired)
  {
    accCollection.Invoke(new Action<string>(AddItem), new Object[] {   value });
  }
  else
  {
    accCollection.Items.Add(value);
  }
}
private void SetDataGrid(bool AutoGenerateColumns, Object DataSource, String DataMember, DataGridViewAutoSizeColumnsMode Mode)
{
  if (this.dataGridView1.InvokeRequired)
  {
    this.dataGridView1.Invoke(new Action<bool, Object, String,   DataGridViewAutoSizeColumnsMode>(SetDataGrid),
                              AutoGenerateColumns, DataSource, DataMember, Mode);
  }
  else
  {
    this.dataGridView1.AutoGenerateColumns = AutoGenerateColumns;
    this.dataGridView1.DataSource = DataSource;
    this.dataGridView1.DataMember = DataMember;
    dataGridView1.AutoResizeColumns(Mode);
  }
}

And Program.cs

 static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
  Application.EnableVisualStyles();
  Application.SetCompatibleTextRenderingDefault(false);
  Application.Run(new Form1());
}

To summary your problem: You have to encapsulate all control-related updates you want to call from another thread than the main thread just like I did it with the two controls.

Some ressources you might want to check for multithreading / tasks http://msdn.microsoft.com/en-us/library/system.threading.tasks.task.aspx http://blogs.msdn.com/b/pfxteam/archive/2009/06/30/9809774.aspx

Answer 2

You have many problems in your code:

• The call to Application.Run() is a blocking call. It won't return until you close your form. So your thread starts when your application is about to exit.

  Just start your thread before calling Run():

  Thread aniSql = new Thread(new ThreadStart(getSalesFigures));
  aniSql.Start();
  Application.Run(new Form1());
  

  A Tip: Start using the debugger and step through your code. You would have noticed that your thread function is never reached.

• You create a second instance of Form1 in the function GetSalesFigures. You have to use the existing instance when polling the state of the checkbox.

• Your thread will perform only a single check and then it returns. You have to write some code in GetSalesFigures to wait for the user to check the checkbox. Otherwise nothing will happen. You can use a ManualResetEvent for waiting on an event:

  ManualResetEvent mre = new ManualResetEvent(false);
  
  void YourThreadFunc() {
      // Wait until someone signals mre
      mre.WaiteOne();
      // start sql
      ...
  }
  

  In your form:

  private void button1_Click(object sender, EventArgs e)
  {
      // trigger the WaitHandle to signal the waiting thread
      mre.Set();
  }