Asynchronous programming

Asynchronous programming

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  ASYNCHRONOUS PROGRAMMING Code Review4/26/13 – Chester Hartin
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  Hopes  Identify whereyou may need asynchronous processing  Implement it with Background workers,Task Parallel Library, or async & await pattern  Learn to refactor synchronous applications into become more responsive
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  Asynchronous vs. Parallel Who remembers my talk about boiling eggs using the parallel extensions?  Concurrency / Boiling several eggs simultaneously  By boiling the eggs in different pots, we are boiling them in parallel to each other.  Now if we do something else while they’re boiling, like cleaning up the kitchen, and we go back to them once they’re done… that task is done asynchronously
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  Asynchronous vs. Parallel Think of parallelism as something that runs independently at the same time as another task  Think of asynchronous operations as something that will let you do things in the meantime while you wait, but once it’s finished, you receive the results
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  Asynchronous  It’s commonto look at asynchronous processes as non-blocking (ie the system won’t lock up, will continue).  So how do we do this?
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  Synchronous Design
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  Asynchronous Design
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  Asynchronous  There areseveral methods  Threads &Thread Pooling  Background workers  Task Parallel Library (TPL)  Asynch & await
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  Example 1 –No threading  lblInfo.Text = ProcessOrder(); private string ProcessOrder() { // really long task that takes for ever }
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  Example 2 –background worker  //ex2  private void bgw_DoWork(object sender, DoWor kEventArgs e)  { e.Result = ProcessOrder(); }  private void bgw_RunWorkerCompleted(object s ender, RunWorkerCompletedEventArgs e)  { lblInfo.Text = e.Result.ToString() ; }
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  Example 3 –TPL (Task Parallel Library )  private void ProcessOrderContinueWith() { var task = newTask<string>(ProcessOrder); task.Start(); task.ContinueWith((parentTask) => { this.Invoke(new Action(() => { lblInfo.Text = parentTask.Result;}));}); lblInfo.Text = "Thinking"; }
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  Example 3 –TPL (cont)  What happens is we’re creating a State machine  This handles everything in the background & keeps track of what task is running & where so it knows where to go back
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  Example 4 --Async & Await private async void ProcessOrderAsync() { var processOrderResult = Task<string>.Factory.StartNew(ProcessOrder); lblInfo.Text = await processOrderResult; }
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  Example 4 --Async & Await  Still a state machine, but way easier to read & implement!
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  Refactoring  Using async& await allows you to utilize most of your existing code