Comparative Asynchronous Programming

Presented at Playgrounds Conf: http://www.playgroundscon.com/

Transcript

1. Comparative
   Asynchronous
   Programming
   

   View Slide

2. View Slide

3. Agenda
   1. Asynchronous programming is hard.
   2. Swift already supports a few async methodologies.
   3. Swift supports some other paradigms.
   4. But lacks support for others.
   

   View Slide

4. Asynchronous Programming:
   Difficult and Subjective
   

   View Slide

5. “Normal” programming
   

   View Slide

6. let returnValue = someFunctionCall()
   

   View Slide

7. Asynchronous programming
   

   View Slide

8. Development is all about tradeoffs
   

   View Slide

9. let file = readFile()
   ...
   readFile() { file in
   ...
   }
   

   View Slide

10. Embrace Tradeoffs
    

    View Slide

11. Swift Has Async Built-in. Sorta.
    

    View Slide

12. Built-in Async Approaches
    

    View Slide

13. Grand Central Dispatch
    

    View Slide

14. NSOperationQueue /
    DRBOperationTree
    

    View Slide

15. POSIX Threads
    

    View Slide

16. Target / Action
    

    View Slide

17. Callbacks / Completion Handlers
    

    View Slide

18. logIn(with: credentials) { result in
    // Handle login success or failure
    }
    

    View Slide

19. Callback Hell
    

    View Slide

20. getCredentialsFromUser() { credentials in
    logIn(with: credentials) { result in
    // Handle login success or failure
    }
    }
    

    View Slide

21. getCredentialsFromUser() { credentials, error in
    if credentials {
    logIn(with: credentials) { login, error in
    if login {
    // Handle login success
    } else {
    // Handle error
    }
    }
    } else {
    // Handle error
    }
    }
    

    View Slide

22. (credentials: Credentials?) -> Void
    (credentials: Credentials?, error: Error?) -> Void
    (result: Result) -> Void
    

    View Slide

23. enum Result {
    case success(T)
    case error(Error)
    }
    

    View Slide

24. Callback Heaven
    

    View Slide

25. Some Async Abstractions are
    Supported in Swift
    

    View Slide

26. Promises & Futures
    

    View Slide

27. getCredentialsFromUser()
    .flatMap { credentials in
    return login(with: credentials)
    }
    .onSuccess { login in
    // Handle login success
    }
    .onFailure { error in
    // Handle login error
    }
    

    View Slide

28. Functional Reactive Programming
    

    View Slide

29. getCredentialsFromUser()
    .flatMap { credentials in
    return login(with: credentials)
    }
    .on(next: { login in
    // Handle login success
    }, error: { error in
    // Handle login error
    })
    

    View Slide

30. View Slide

31. gerstureRecognizer.rx
    .event
    .map { recognizer in
    return recognizer.location(in: recognizer.view)
    }
    .bind(to: circle.rx.center)
    

    View Slide

32. Actor Model
    

    View Slide

33. View Slide

34. Actor Model
    

    View Slide

35. Some Async Abstractions are
    Impossible in Swift
    

    View Slide

36. Async / Await
    

    View Slide

37. async func logIn() -> Login {
    let credentials = await getCredentialsFromUser()
    return await logIn(with: credentials)
    }
    

    View Slide

38. Coroutines and Generator Functions
    

    View Slide

39. func fibGenerator*() -> Int {
    var i = 0, j = 1
    repeat {
    let next = i + j
    yield next
    (i, j) = (j, next)
    } while true
    }
    fibGenerator() // returns 1
    fibGenerator() // returns 2
    fibGenerator() // returns 3
    fibGenerator() // returns 5
    

    View Slide

40. Wrap Up
    1. There’s no “right way” to do async programming.
    2. Asynchronous abstractions built into Swift aren’t great.
    3. There are some cool things you can do in Swift.
    4. There are other cool things that you can’t do in Swift.
    

    View Slide

41. View Slide