The Subtle Bliss of Coroutines @mambo_bryan 01

02 Design Centric Engineer Brian Odhiambo Dishwasher @ Baobab Circle Co-organizer @ KotlinKenya Maintaining @ KotlinBits Yeah am all about that UI/UX & Kotlin

HOW How to use coroutines WHY Why use coroutines The World of Concurrency 03 WHAT What are coroutines synchronous! asynchronous! structured!

The WHAT? What are coroutines

Works concurrently with the rest of the code Similar to threads but lightweight Is not tied to any thread Expressed in a structured way What are coroutines? An instance of suspendable computation

An Example Coroutines marked with suspend import kotlinx.coroutines.* suspend fun main() { println("Starting Work") doWork() } suspend fun doWork(){ delay(1000) println("Finished Work") } Starting Work Finished Work 06

The WHY? Why coroutines

Prevents the callback hell problem Easily maintainable & scalable Gives you more control of how you handle jobs Less resource intensive than JVM threads (2mb) Why Coroutines ? sendRequest( onSuccess = { sendAnotherRequest( onSuccess = {...}, onFailure = {...}, ) }, onFailure = {...} )

Why Coroutines ? FROM : sendRequest( onSuccess = { sendAnotherRequest( onSuccess = {...}, onFailure = {...}, ) }, onFailure = {...} ) TO : val result = sendRequest() if(response != null){ val result = sendAnotherResponse() ... } ...

The HOW? How do you coroutine

Example custom coroutine marked with suspend import kotlinx.coroutines.* fun main() { println("Starting Work") GlobalScope.launch { doWork() } Thread.sleep(2000) } suspend fun doWork(){ delay(1000) println("Finished Work") } Starting Work Finished Work 11

Example II custom coroutine marked with suspend import kotlinx.coroutines.* fun main() { println("Starting Work | ${Thread.currentThread().name}") GlobalScope.launch { doWork("1") } CoroutineScope(Dispatchers.IO).launch { doWork("2") } Thread.sleep(3000) } suspend fun doWork(name: String){ delay(1000) println("Finished Work $name | ${Thread.currentThread().name}") } Starting Work | main Finished Work 1 | DefaultDispatcher-worker-2 @coroutine#1 Finished Work 2 | DefaultDispatcher-worker-2 @coroutine#2 12

Next Session Advanced Coroutine Concepts

Jobs What are Jobs and what is their lifecycle... Builders How can you use builders to create coroutines Advanced Coroutine Concepts 14 Contexts What are contexts and what is context switching and so much more!

One Last Thing For the community

KotlinBits 😎 A fun and easy way to learn Kotlin in small bits and pieces. React, Comment & Share kotlinbits.vercel.app

16 mambo_bryan MamboBryan Thank you! Have a nice Kotlin KotlinBits kotlinbits.vercel.app