How do I use the TIMER for slowing down a FOR

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2.33/5 (3 votes)

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Hello all,

My problem is that I have this method and I don't know how to use the Timer class to slow down the FOR. At the moment I am using the Thread.Sleep but I really hate it because it makes the interface "dead" until the script is done.

How can I change the script in such a way to use the Timer Class instead of the Thread.Sleep so that I can use the UI while the script is still running?

C#

private void ProcessCsvFile(string pFileContent)
       {
           //set the delimiters for string seperation
           string[] stringSeparators = new string[] { "\r\n" };
           //now the file content gets split into an array where each line of the .csv-file gets into on element of the array
           string[] dataLines = pFileContent.Split(stringSeparators, StringSplitOptions.None);

           // X = counter for how many orders have been sent
           int x = 0;
           //Check if there is a Session ID
           string CookieID = textBox1.Text;
           if (string.IsNullOrEmpty(CookieID))
           {
              SystemSounds.Beep.Play();
              MessageBox.Show("Please provide a session ID!");
           }
           else
           {
               //loop over all of the lines
               for (int i = 0; i < dataLines.Length; i++)
               {

                   //dont process the first line, since its the description line
                   if (i != 0 && dataLines[i] != "")
                   {
                       x++;
                       //split line by ;
                       string[] csvColumns = dataLines[i].Split(',');

                       label3.Text = x.ToString();
                       label3.Refresh();

                       // Send order based on ID, Count and Price
                       Send_BuyOrder(csvColumns[0], csvColumns[1], csvColumns[2]);
                       // Write in the data grid
                       dataGridView1.Rows.Add(csvColumns[0], csvColumns[1], csvColumns[2], "Done");
                       dataGridView1.Refresh();
                       // Sleep for 4seconds
                       if (x < dataLines.Length -1)
                       {
                           Thread.Sleep(4300);
                       }

                   }
               }
               SystemSounds.Beep.Play();
               MessageBox.Show(x + " orders have been set!");
           }
       }

Posted 28-Aug-14 9:30am

Arthfael

Updated 28-Aug-14 9:35am

v2

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Comments

Richard MacCutchan 28-Aug-14 15:32pm

And your question is ... ?

[no name] 28-Aug-14 15:34pm

You don't.

Sergey Alexandrovich Kryukov 28-Aug-14 15:36pm

The whole idea of "slowing down for" with a timer looks really bad. I don't say you don't need to "slow down" — maybe you need to. If you explain your ultimate goal, the behavior you want to have, not how, I'll be able to help you, almost certainly.
Short hint: forget timer, use an extra thread.
—SA

Arthfael 28-Aug-14 15:40pm

Well, I have a CSV file that has ID's / Count and Price for a couple of products that I buy on a daily basis. The method parses the file and sends a HTTP POST request every 4.3seconds but because I am using the Thread.Sleep, the UI is blocked until the script is done. (it takes 5-10minutes to process and send all the requests)

Sergey Alexandrovich Kryukov 28-Aug-14 15:47pm

Certainly, use a separate thread. 100% certainly. I would also question the need of regular POST, but the alternative would be using server push, not a very usual stuff.
—SA

Arthfael 28-Aug-14 15:50pm

Thank you Sergey. I will try to do it with a separate thread.

Sergey Alexandrovich Kryukov 28-Aug-14 16:01pm

Great. Ask your questions if you face any problems.
—SA

2 solutions

Solution 1

To keep the UI responsive during busy processes you can use the Application.DoEvents method

http://msdn.microsoft.com/en-us/library/system.windows.forms.application.doevents(v=vs.110).aspx[^]

Posted 28-Aug-14 9:40am

ZurdoDev

Comments

Sergey Alexandrovich Kryukov 28-Aug-14 15:45pm

Ryan, this is a really, really bad approach which can cause many problems. A real (and even the simplest way) would be using an extra thread.
I did not answer because I wanted to wait OP's explanation of the purpose.
—SA

ZurdoDev 28-Aug-14 15:50pm

Extra thread is another option. More complicated but still an option.

DoEvents() is still supported in .Net 4.5 so Microsoft must not think it is too bad of an option. It's certainly easier than multiple threads. :)

Sergey Alexandrovich Kryukov 28-Aug-14 16:00pm

I disagree. No, an extra thread is less complicated... DoEvents works, but is a source of troubles. :-)
—SA

ZurdoDev 28-Aug-14 16:02pm

Out of curiosity, what kind of troubles? I used it many years ago but have been doing web since.

Sergey Alexandrovich Kryukov 28-Aug-14 16:06pm

Hard to answer quickly, as I was careful to avoid it for a long time. But, basically, it potentially makes UI thread not responsive, because it can be hard to guarantee that the time slices between DoEvents are small enough. Worse, it can create infinite recursion, and broken order of execution, because some calls between DoEvents may also invoke events. It can become a bomb of deferred action...
—SA

Dave Kreskowiak 28-Aug-14 16:39pm

Rentering event handlers while they are still executing is one of those problems.

DoEvents is good for "simple" things, not the one described by the OP.

In order to use DoEvents, you must be VERY careful about preventing non-reentrant code from executing again, for example, a button click that starts a long-running process can be clicked again if you're not careful.

I say DoEvents is a method of last resort and prefer to use Tasks and Threads over anything else.

ZurdoDev 28-Aug-14 16:40pm

Fair enough.

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PIEBALDconsult · Accepted Answer · 2014-08-28T10:44:00

I agree with using a Thread rather than a Timer.

Unlike Sleep, Join "Blocks the calling thread until a thread terminates, while continuing to perform standard COM and SendMessage pumping."

http://msdn.microsoft.com/en-us/library/95hbf2ta(v=vs.110).aspx[^]

So here's a simple little experiment in wrapping a Sleep in a Thread and then Joining on it:

C#

public static void
SleepWalk
(
  int millisecondsTimeout
)
{
  System.Threading.Thread t = new System.Threading.Thread
  (
    delegate() { System.Threading.Thread.Sleep ( millisecondsTimeout ) ; }
  )
  {
    IsBackground = true
  ,
    Priority = System.Threading.ThreadPriority.Lowest
  } ;

  t.Start() ;

  t.Join() ;

  return ;
}

It seems to work.

I also agree that maybe you need to rethink your design.