Asynchronous programming 20180607
- 1. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA YIFAN XING - 2018 ASYNCHRONOUS PROGRAMMING Yifan Xing SCALA.CONCURRENT AND MONIX! @yifan_xing_e
- 2. 01 Synchronous vs. Asynchronous Differences Futures & Promises Debugging Async Programs Monix A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA 02 03 04 05Overview ASYNCHRONOUS PROGRAMMING: SCALA.CONCURRENT AND MONIX!
- 3. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Concurrency Synchronous Asynchronous Single-threaded Multi-threaded YIFAN XING - 2018 @yifan_xing_e
- 4. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Synchronous: Single-threaded YIFAN XING - 2018 Task 1 Task 2 Task 3 @yifan_xing_e
- 5. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Synchronous: Multi-threaded YIFAN XING - 2018 Task 1 Task 2 Task 3 @yifan_xing_e
- 6. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Asynchronous: Single-threaded YIFAN XING - 2018 Task 1 Task 2 Task 3 @yifan_xing_e
- 7. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Asynchronous: Multi-threaded YIFAN XING - 2018 Task 1 Task 2 Task 3 @yifan_xing_e
- 9. YIFAN XING - 2018 Scala.concurrent: Future Computation Incomplete: Computation Completed: Future is not completed Future is completed: with a Value => Success Future is completed: with an Exception => Failure An object holding a value which may become available at some point Immutable A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALAA TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e Future
- 10. YIFAN XING - 2018 Example: Callbacks Multiple callbacks may be registered; NO guarantee that they will be executed in a particular order. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e
- 11. YIFAN XING - 2018 Example: Callbacks Chain callbacks Allow one to enforce callbacks to be executed in a specified order. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e
- 12. YIFAN XING - 2018 Example: Callbacks A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e Exception in callback: NOT propagated to the subsequent andThen callbacks.
- 13. YIFAN XING - 2018 Example: Transformations A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e
- 14. YIFAN XING - 2018 Example: Transformations More generic & flexible A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e
- 15. YIFAN XING - 2018 Example: Transformations If no match cases or original future contains a valid result: New future will contain the same result as the original one. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALAA TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e Evaluated only after a Failure
- 16. YIFAN XING - 2018 Example: Transformations If both futures failed, the resulting future holds the throwable object of the first future. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e
- 17. YIFAN XING - 2018 Scala.concurrent: Promises A writable, single-assignment container Can create a Future Can complete a Future, only ONCE A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e Promise:
- 18. YIFAN XING - 2018 Example: Promises A Promise can be completed at most ONCE. If the promise has already been fulfilled, failed or has timed out, calling this method will throw an IllegalStateException. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e
- 19. YIFAN XING - 2018 Example: Promises If the promise has already been completed returns false, or true otherwise. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA @yifan_xing_e
- 20. YIFAN XING - 2018 A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Problem in A Client-facing Interface @yifan_xing_e
- 21. YIFAN XING - 2018 A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA p.future Problem in A Client-facing Interface @yifan_xing_e
- 23. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA What is Monix? Asynchronous, event-based programs Data type: Task, etc. "Factory" of Future instances Lazy & asynchronous computations YIFAN XING - 2018 @yifan_xing_e
- 24. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Monix: Task YIFAN XING - 2018 Lazily evaluated Evaluated when call runAsync Trigger side effects @yifan_xing_e
- 25. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Monix: Task Callback YIFAN XING - 2018 Eagerly evaluate task Register callbacks Similar to Future#onComplete @yifan_xing_e
- 26. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Monix: Eager/ Lazy YIFAN XING - 2018 Evaluate eagerly Equivalent to Future#successful Defer eager evaluation Similar to Task#eval @yifan_xing_e
- 27. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Monix: Memoization YIFAN XING - 2018 Evaluated lazily Not memoized, recompute each time the Task is executed. Evaluate lazily Evaluated exactly ONCE Result is memoized @yifan_xing_e
- 28. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Monix: MemoizeOnSuccess YIFAN XING - 2018 Exceptions are not cached. Only cache the first successful result @yifan_xing_e
- 29. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Monix: Alternative Thread Pool YIFAN XING - 2018 Overrides default scheduler Overriding the "default" scheduler can only happen ONCE Task is immutable @yifan_xing_e
- 30. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Monix: CancelableFuture YIFAN XING - 2018 Calling it multiple times has the same side- effect as calling it only once. @yifan_xing_e
- 31. - A value - Executed when constructed - Eager evaluation - ExecutionContext needed whenever use operators A function - Execution controllable by user - Lazy evaluation - ExecutionScheduler needed whenever - use runAsync MonixFuture Eager/Lazy A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA
- 32. - Memoized by default - Evaluated once - Store result Explicitly use memoization operators - Evaluated whenever needed - Referential transparency - MonixFuture Memoization A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA
- 33. - Sometimes errors are not propagated Scheduler.reportFailure - Defaults to System.err - Allow customized logging tools - MonixFuture ErrorHandling A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA
- 34. Future Monix A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA
- 35. FutureMonix A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA
- 36. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Debugging BEST PRACTICES In Asynchronous Programs @yifan_xing_e
- 37. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA
- 38. Writing Async Code 1. Rethink before adding more code 2. Adding more code to fix problems will usually add more bugs D e b u g 1. Test code in isolation 2. Observe what is happening 3. Confirm behavior before moving on T e s t
- 39. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Using Await & Print YIFAN XING - 2018 @yifan_xing_e TimeoutException if after waiting for the specified time awaitable is still not ready atMost may be: A finite positive duration Negative (no waiting is done) Duration.Inf for unbounded waiting
- 40. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA ScalaTest: ScalaFutures YIFAN XING - 2018 @yifan_xing_e Default timeout 150ms TestFailedException if not finished after timeout
- 41. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Resources: Async Debugger & Capture YIFAN XING - 2018 @yifan_xing_e IntelliJ Capture (2017): Iulian Dragos - Async Debugger in Scala IDE IntelliJ IDEA 2017.1 EAP Extends Debugger with Async Stacktraces Developer's Explanation Debugging Tutorial Async Stacktraces Stack Retention Scala IDE Doc Demo: Jamie Allen Rethink the Debugger: Scala Days 2014
- 42. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA Using Async Debugger / Capture YIFAN XING - 2018 @yifan_xing_e Substituting its parts related to the asynchronous code execution with where it was called Sender: Async code executor Receiver: executed code Config exact signatures of methods of the async code Stores the stack and variables info in a map (1000 stacks), where the key is a parameter with the specified number.
- 43. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA YIFAN XING - 2018 @yifan_xing_e ( Sorry Alex :P )
- 44. A TOUR OF ASYNCHRONOUS PROGRAMMING IN SCALA YIFAN XING - 2018 @yifan_xing_e
- 45. T H A N K Y O U @yifan_xing_e