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Asynchronous Programming in Kotlin with Coroutines
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 DevMeetup #1
- 2. 2 •• Asynchronous progammingin Kotlin with Coroutines 🍕 🍕 🍕 Tensorflowing like a pro - without a clue
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- 4. 4 •• How programmingworks 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 withlong 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 isa 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 •• •• Suspendfunctions - A function ‘super powers’ - It’s a function which can suspend and return a value later on
- 8. 8 •• •• Suspendfunctions II - Suspension points - Many things work out-of-the box - Loops - Exceptions - Higher-Order-Functions - …
- 9. 9 •• suspension functionsare designed to imitate sequential behavior by default
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- 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 functionscannot 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
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- 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