Task-based asynchronous programming (C#)

Programming paradigm, using Task<T> objects

• similar to futures/promises
• async keyword is used to declare an asynchronous function, which runs alongside the caller
  • can return a Task, Task<T> or void (async event handler, I guess background work where you don't need a response)
  • useful for possibly blocking routines (like something that must wait for a response over a network)
  • an async function runs until it has no more work to do (awaiting some data to return back)
  • as soon as the awaited data is ready, resume the async function and compute/set the result in its Task, marking it completed
• await unwraps a Task<T> object, while giving control back to the caller
• for I/O bound code, await an async operation that returns a Task<T>
• for CPU-bound code, await an operation which was started on a background thread with Task.Run
• Task.Run takes a Func<Task>
  • Func<TResult> is just a lambda (in this case it can be used as a closure)
  • delegate keyword can be used to declare a type (class?) which can point to a function
  • Func<bool> methodCall = a.mymethod; is an example of defining a delegate without the delegate keyword