Async await how to use return values

Question

I have a windows service that I have inherited from another developer, it runs very slow and has numerous slow call to the eBay API. I wish to speed it up without too much refac

Answer 1

Try this code:

public async Task ProcessAdditionalProductDetialsAsync(ItemType oItem) { 
    String additionalProductDetails = await Task.Run(() => {
       if (oItem.ItemSpecifics.Count > 0) {
          foreach (NameValueListType nvl in oItem.ItemSpecifics) { 
             if (nvl.Value.Count > 0) {
                 string retval = String.Empty;

                 foreach (string s in nvl.Value) {
                     retval += "
" 
                       + nvl.Name + ": " + s + "
";
                 }
             }
          }
       }
       return retval;
     }
     return additionalProductDetails;
 }

Usage:

private async void GetAdditionalProductDetailsAsync(Action callback) {
   string apd = await ProcessAdditionalProductDetialsAsync();
   callback(apd);
}

private void AdditionalProductDetailsRetrieved(string apd) {
    // do anything with apd
}