Need help on Backgroundworker

Question

*Note:Rephrasing my question based on user's comments.

Need help on how to use .Net's Backgroundworker thread for the following purpose to increase UI responsiveness and performance in my .Net winforms application. When user clicks "Calculate" button in UI form,I'm doing this:

1.Get a list of categories C from database[this is typically around 10]

2.For each category C, do the following:

a.Call a third-party library, do some processing and calculate category price.

b.Get a list of products[This is typically around 800].

c.For each product, calculate its price using its category price from above.

d.Update this price of each product back in the database using a stored proc.

3.Update the progress back[or report any error message] to a form in UI.

FYI,I want to use Backgroundworker for steps #c and #d above.

I tried using Backgroundworker in my method.I put calls to InitializeBackgroundworker() and RunWorkerAsync() in the outermost loop[ie. step 2].But looks like, Backgroundworker is getting invoked only for the first category.What am I missing here?

So my question is, where do I make a call to InitializeBackgroundworker() and RunWorkerAsync()? And how do I make sure these 2 methods get called for each category?

Thanks for reading.

Answer 1

See the example here:

http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx

Answer 2

Try something like this for a start.

BackgroundWorker worker = new BackgroundWorker();

void SomeForm_Load(object sender, EventArgs e)
{
  // setup the BackgroundWorker 
  worker.WorkerReportsProgress = true;
  worker.DoWork += new DoWorkEventHandler(worker_DoWork);
  worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
  worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_Completed);
}

void SomeControl_Click(object sender, EventArgs e)
  List<Category> categories = DataBase.GetSomeCategories(); // [1] get Category list
  // start the BackgroundWorker passing in the categories list.
  worker.RunWorkerAsync(categories);
}

void worker_DoWork(object sender, DoWorkEventArgs e)
{
  int progress = 0;
  var categories = e.Argument as List<Category>;       
  categories.ForEach(category =>                         // [2] process each Category
  {
    ThirdPartyControl.DoSomeProcessing(category);        // [2.a]
    var categoryPrice = CalculateCategoryPrice(category);
    var products = GetListOfProducts(category);          // [2.b] 
    products.ForEach(product =>                          // [2.c] process each Product
    {          
      var productPrice = CalcProductPrice(categoryPrice); 
      DataBase.UpdateProduct(product, productPrice);     // [2.d]
      progress = //...calculate progress...
      worker.ReportProgress(progress);                   // [3]
    });
    progress = //...calculate progress...
    worker.ReportProgress(progress);                     // [3]
  });
  worker.ReportProgress(100);
}

void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
  //...update some UI stuff...
  progressBar.Value = e.ProgressPercentage;
}

void worker_Completed(object sender, RunWorkerCompletedEventArgs e)
{
  //...all done...
}

You can always break it into multiple BackgroundWorkers as your understanding increases.