need help in waiting for async webclient post response

Question

Hi i am posting to a url using following method. it works fine for me. i have created five task inside this.

private async Task CreateMultipleTasksAsync(string url, ExtendedWebClient oExtendedWebClient, string sParam)
        {

            try
            {
                Task<string> download1 = oExtendedWebClient.ProcessURLAsync(url, oExtendedWebClient, sParam);
                Task<string> download2 = oExtendedWebClient.ProcessURLAsync(url, oExtendedWebClient, sParam);
                Task<string> download3 = oExtendedWebClient.ProcessURLAsync(url, oExtendedWebClient, sParam);
                Task<string> download4 = oExtendedWebClient.ProcessURLAsync(url, oExtendedWebClient, sParam);
                Task<string> download5 = oExtendedWebClient.ProcessURLAsync(url, oExtendedWebClient, sParam);
                lst_tasks1.Add(download1);
                lst_tasks2.Add(download2);
                lst_tasks3.Add(download3);
                lst_tasks4.Add(download4);
                lst_tasks5.Add(download5);

                // Await each task.
                 Result1 = await download1;
                 Result2 = await download2;
                 Result3 = await download3;
                 Result4 = await download4;
                 Result5 = await download5;

            }
            catch (Exception ex)
            {
                ErrorLog.createLog("ex.StackTrace = " + ex.StackTrace + " ex.tostring = " + ex.ToString());
            }

        }

what i need to achieve is if any task returns string containing "START" word stop waiting and continue ..

The way i am doing this is as follows :

   Task.WaitAll(lst_tasks1.ToArray());
if (Result1.ToLower().Contains("START") && !Result1.Contains(sTextSearch))
{
    goto call2;
}
else
{

worker.ReportProgress(0, "Waiting for tasks2");
Task.WaitAll(lst_tasks2.ToArray());

and so on waitng up to task 5. is there any way to do this code using Task.waitany please suggest

Answer 1

You could try using the solution given in this post

You will need to pass your condition to this method as a predicate.

Assuming lst_tasks contains all the tasks, you could do something like this.

await WhenAny(lst_tasks, s => s == "START");

This will stop waiting once any task returns START.