Is it possible / how to create an empty Future, set the necessary callbacks for its completion, and then set its result at a different point in time? In pseudocode (uncompilable) that would look like the following: val future: Future[Int] = Future.empty() future.onComplete { case Failure(exception) => println(s"Exception: $exception") case Success(value) => println(s"Done: $value") }… Read More Creating an empty Scala Future to be completed externally

I’d like to understand whether a function that may take time to execute will delay the execution of the function after it. Let me share the code: First, we have a function that calculates an average value based on. This should be almost instant if the user has a few habits, but if the user… Read More Are functions in Swift called in parallel by default or does the first one need to finish execution before the next is called?

let task = Task { await function(parameter: 2) } I would like to run this function inside the task some other time in the future. Is it possible to achieve this in Swift? Currently, function is executed immediately. My reason to do this is: pass multiple tasks to a function and run all of them… Read More Is it possible to define a Task and not run it immediately?

Why are most SwiftUI types (like Color or Text) non-sendable? Is there a specific reason for this? Isn’t that kind of the point of SwiftUI views? Or am I missing something? struct Test: Sendable { let color: Color // Warning: Stored property ‘color’ of ‘Sendable’-conforming struct ‘Test’ has non-sendable type ‘Color’ } I want to… Read More Why are most SwiftUI Views non-sendable?

Familiarizing myself with concurrency, so started writing a simple ping cli with concurrent calls (let’s ignore that I’m not really measuring pings). Problem is, I can’t close the channel properly for the range loop while also waiting for all the goroutines to finish. If I want to concurrently call the ping function, I can’t synchronize… Read More Go concurrency, goroutine synchronization and closing channels

I am very new to Scala and following the Scala Book Concurrency section (from docs.scala-lang.org). Based off of the example they give in the book, I wrote a very simple code block to test using Futures: import scala.concurrent.Future import scala.concurrent.ExecutionContext.Implicits.global import scala.util.{Failure, Success} object Main { def main(args: Array[String]): Unit = { val a =… Read More Waiting on main thread for callback methods

I am trying to implement retry-mechanism using a recursive method. Although the method already returned the list, the consecutive lines of code are executed as well. I am sure I am missing something very obvious which a trained eye can spot in a second. How can I rework the recursion, so I get rid of… Read More Code is executed after return in recursive method

While testing concurrency, I found something unexpected. Concurrency was controlled using concurrentHashMap and AtomicLong. public class HumanRepository { private final static Map<Long, Human> STORE = new ConcurrentHashMap<>(); private AtomicLong sequence = new AtomicLong(); public void save(Human human) { STORE.put(sequence.incrementAndGet(), human); } public int size() { return STORE.size(); } public Long getSeq() { return sequence.get(); }… Read More Java unexpected concurrent result