threading in a Custom Collection

[Juvil John]

Hi All, I'd like to make a separate thread in inserting of data into the Custom Collection I have and fires an event when its done so it would be bound to a grid. Is it possible? here is my example code.

public class Details : List<Details.Detail>
{
    public delegate void \_WorkComplete();
    public event \_WorkComplete WorkComplete;

    public void AddDataSource(object value)
    {
        Thread worker = new Thread(new ParameterizedThreadStart(dowork));
        worker.Start(value);
    }

    private void dowork(object value)
    {
        ArrayList list = (ArrayList)value;
        foreach (Item item in list)
        {
            this.Add(new Detail { FIELD1 = item.Code1, FIELD2 = item.Code2 });
        }
        if (WorkComplete != null) WorkComplete();
    }

    public class Detail
    {
        private string field1;
        private string field2;

        public Detail()
        {
            field1 = string.Empty;
            field2 = string.Empty;
        }

        public string FIELD1
        {
            get { return field1; }
            set { field1 = value; }
        }

        public string FIELD2
        {
            get { return field2; }
            set { field2 = value; }
        }
    }
}

so in the UI side i could do

private Details details = new Details();

protected void Page_Load(object sender, EventArgs e)
{
details.OnWorkComplete += new Details._WorkComplete(details_AddComplete);
details.AddDataSource(source1);
details.AddDataSource(source2);
}

void details_AddComplete()
{
grid1.DataSource = details;
grid1.DataBind();
}

[Lost User]

Search in google for cross-thread-exception. You cannot change something in control from another thread. "grid1.DataSource = details;" -> Cross Thread Exception

void details_AddComplete()
{
Invoke(new MethodInvoker(AddComplete));
}

void AddComplete()
{
grid1.DataSource = details;
grid1.DataBind();
}

[Juvil John]

that does not fire an error the "details" is created on the same thread. as the "grid1". not the comment I expected but thanks for the reply.

modified on Wednesday, August 12, 2009 5:07 AM

[Nicholas Butler]

Assuming you add all your sources in Page_Load, you could do this: In AddDataSource, just add the source to a collection inside Details. Add a method Details.StartProcessing() which starts the background work. So Page_Load would look like:

details.AddDataSource( source1 );
details.AddDataSource( source2 );
details.StartProcessing();
}

As Stan said, your event will be fired on the background thread. Either use a BackgroundWorker instead of a Thread, or use Invoke before you update the grid. Nick

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