Question

I have been playing around with methods of calling of calling a method safely in threadsafe manner in .net 2.0.

My treeview is populated from a call to a database on a separate thread;

Below is my attempt to use my InvokeFunction method ( shown below) …it works, but I was hoping that there was a nicer way to write this…any thoughts on this?

InvokeFunction(delegate() { TreeView1.Nodes.Clear(); });



delegate void FunctionDelegate();
private delegate void ThreadSafeProcess(FunctionDelegate func);
private void InvokeFunction(FunctionDelegate func)
{
  if (this.InvokeRequired)
  {
    ThreadSafeProcess d = new ThreadSafeProcess(InvokeFunction);
    this.Invoke(d, new object[] { func });
  }
  else
  {
    func();
  }
}

Answer 1

BackgroundWorker is a cleaner solution in .NET 2.0.
It will create a thread for you and take care of synchronization.

You add BackgroundWorker component to you Form in the design mode.
You subscribe to DoWork event. The method subscribed to this will be execute in a background thread when you call backgroundWorker.RunWorkerAsync() in your UI thread.

When you need to interact with UI thread from your background thread you call backgroundWorker.ReportProgress.
This will trigger ProgressChanged event. ProgressChanged event is always executed in UI thread.
You can use userState parameter of backgroundWorker.ReportProgress to pass any data to UI thread. For example in your case the data that is needed to add new TreeView nodes.
You will actually add new nodes inside of ProgressChanged event handler.

Here is the link to MSDN: http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx.

Keep in mind you don’t have to use percentProgress parameter of the method ReportProgress method. Although it is convenient when you have a progress bar to reflect background work progress.