Asynchronous Programming in Kotlin with Coroutines
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This document summarizes a meetup about asynchronous programming in Kotlin using coroutines. It discusses how coroutines allow direct-style asynchronous code by suspending coroutines instead of blocking threads. Coroutines appear like regular blocking code but are lightweight like threads. Suspending functions can pause and return values later. Demos show using coroutines with builders, contexts, and channels for asynchronous programming compared to callbacks and RxJava.
Asynchronous Programming in Kotlin with Coroutines
- 1. 1 •• Rhein-Neckar Dev Meetup #1
- 2. 2 •• Asynchronous progamming in Kotlin with Coroutines 🍕 🍕 🍕 Tensorflowing like a pro - without a clue
- 3. 3 •• Coroutines Asynchronous programming in Kotlin
- 4. 4 •• How programming works Intro Do something (create a resource) ↓ Wait (for completion) ↓ Do something (send it to backend) ↓ Wait (for the response) ↓ Do something (process response or try again) ↓ …
- 5. 5 •• Dealing with long running tasks Asynchronicity - Direct style - max 16 ms - Blocking the main Thread - Callback - Error Handling - Callback Hell - Futures (RxJava, Promises, …) - Idea: we wrap the result - Pro: nice code, errors, good looking - cons: complex - Coroutines - Direct style
- 6. 6 •• What is a Coroutine? - It’s an instance of a suspendable computation - General concept was already created in 1958 - Similar to a very lightweight Thread – cheap in creation - Looks like regular blocking code - Coroutines give us a way to write code that feels imperative, even if it is asynchronous.
- 7. 7 •• •• Suspend functions - A function ‘super powers’ - It’s a function which can suspend and return a value later on
- 8. 8 •• •• Suspend functions II - Suspension points - Many things work out-of-the box - Loops - Exceptions - Higher-Order-Functions - …
- 9. 9 •• suspension functions are designed to imitate sequential behavior by default
- 10. 10 •• Setup
- 11. 11 •• Demo I - Sample + Performance
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- 20. 20 •• Reuse closure / state object State Machine vs Callbacks Easier loop
- 21. 21 •• Suspending functions cannot be invoked from regular functions • launch (fire and forget) • async (and await) • Returns a Deferred • runBlocking • Not keywords but functions! Coroutine Builder
- 22. 22 •• Demo II – Coroutine Builders
- 23. 23 •• Coroutine Context - *without* - UI - CommonPool - Unconfined
- 24. 24 •• Demo III – Channels and Actors - Comparison RX
- 26. 26 •• Links & References - Coroutines guide Informal - https://github.com/Kotlin/kotlin-coroutines/blob/master/kotlin-coroutines-informal.md - Coroutine guide reactive - https://github.com/Kotlin/kotlinx.coroutines/blob/master/reactive/coroutines-guide-reactive.md - Deep dive into Coroutines on JVM, KotlinConf 2017 – Roman Elizarov https://www.slideshare.net/elizarov/deep-dive-into-coroutines-on-jvm-kotlinconf-2017 - Images from https://www.pexels.com