Question regardingThreading

[archana]

Hi all,

I am having application in c# with on main form and other 3 classes.

Say suppose i have class1, class2.

I have progressbar in main form which i have to update.

I have one method in main class which is my thread procedure.

In thread procedure i am calling method of class1. In method of class
one i am calling method of class2.

And in method of class2 i am raising one event with parameter as
percengate which i am trapping in class1. and again in class1 i am
raising that event which is getting trapped in main form.

This whole process is in thread.

My question is what i am doing as said above is write or not. Means
whether i am updating UI thread properly or not by raising event.

Please correct me if i am wrong.

Thanks in advance.
Archana.

 

[Jon Skeet [C# MVP]]

I am having application in c# with on main form and other 3 classes.

Say suppose i have class1, class2.

I have progressbar in main form which i have to update.

I have one method in main class which is my thread procedure.

In thread procedure i am calling method of class1. In method of class
one i am calling method of class2.

And in method of class2 i am raising one event with parameter as
percengate which i am trapping in class1. and again in class1 i am
raising that event which is getting trapped in main form.

This whole process is in thread.

My question is what i am doing as said above is write or not. Means
whether i am updating UI thread properly or not by raising event.

No. Event handlers (by default, anyway) execute in whatever thread
raises the event. When you update the main form, you should use
Control.Invoke/BeginInvoke to make sure you're accessing the UI in the
appropriate thread.

Jon

 

[archana]

Hi,
thanks for your reply.

Here i am posting my code :-
namespace class1
{

public delegate void ProgressEventHandler( object sender,
CustomEventArg e );

public class DataReaderWriter : IDisposable
{
public event ProgressEventHandler OnProgress;
private DataClient dcReader;

public DataReaderWriter()
{
this.dcReader.ChangedPercentage
+= new CustomEventHandler(this.InsertProgress);

}
public void InsertProgress(object
sender, CustomEventArg e)
{
OnProgress(sender,e);
}
public void StartProcess()
{
this.dcreader.StartProcess1();

}

}

}


Public classs DataClient()
{

public delegate void CustomEventHandler( object sender, CustomEventArg
ev );
public event CustomEventHandler ChangedPercentage;

Publiv void StartProcess1();
{
CustomEventArg args = new CustomEventArg();
args.StatusOfProcess = precentage;
args.FileName = this.fileName;
if( ChangedPercentage != null )
{
ChangedPercentage( this, args );
}
}

}

And code in my main form is like :-

On button click:-

this.dbFileReader.OnProgress += new
ProgressEventHandler(this.ProgressStepChange);
workerMatchThread = new Thread(new ThreadStart(StartProcess3));
workerMatchThread.Start();


public void StartProess3()
{
This.dbreader. StartProcess
}

private void ProgressStepChange(object sender,CustomEventArg e)
{
if(e.StatusOfProcess < 100)
{
this.pgr.Value = e.StatusOfProcess;
this.txtFileName.Text = e.FileName;
}
}


Please tell me If i am wrong.

Thanks in advance.

 

[Ravi Ambros Wallau]

Hi,
I didn't read all of your post, but I believe that a progress should be
update once in a second, or even in a larger period.
With this in mind, I would create a timer in the form to update your
controls - this timer should access some property on your thread that
indicates the progress. This is really light. I think that's the easier
solution...

 

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,


At some point you need to send the event to the UI thread. as you have a
link of calls when only at the end you update your UI you need to use
InvokeRequired to check if you need to invoke or not.

alternatively you can use control.invoke in the procedure that started the
thread and do all the other calls right in the UI thread, unless that the
methods you call do a long processing you should consider this approach.

 

[Jon Skeet [C# MVP]]

Please tell me If i am wrong.

Yes - you've got no calls to Control.BeginInvoke/Invoke, so you're
accessing the UI from the wrong thread. See
http://www.pobox.com/~skeet/csharp/threads/winforms.shtml
for more information.