Efficient Async Coding in Kotlin Coroutines - BoJUG

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Rivu Chakraborty Efficient Async Coding in Kotlin Coroutines 1 Bangalore JAVA User Group (BoJUG) - Year’s First Meetup - Full Day - Informatica - Jan, 19, 2019 19/01/19

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Rivu Chakraborty BYJU’S @rivuchakraborty Efficient Async Coding in Kotlin Coroutines 2

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Rivu Chakraborty BYJU’S @rivuchakraborty About Me ● Sr Software Engineer (Android) - BYJU’S ● Instructor - Caster.io ● Google Certified Associate Android Developer ● DroidJam Speaker ● Author - Reactive Programming in Kotlin ● Author - Functional Kotlin ● Author - Coroutines for Android Developers (WIP)

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@rivuchakraborty

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Books https://www.packtpub.com/application-de velopment/reactive-programming-kotlin https://www.packtpub.com/application-dev elopment/functional-kotlin https://leanpub.com/coroutines-for-androi d-developers Work in Progress

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Efficient Async Coding in Kotlin Coroutines Async => Concurrency

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Concurrency ● Ability to execute multiple code blocks at the same time @rivuchakraborty

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Concurrency ● Ability to execute multiple code blocks at the same time ● Not only for Android Developers @rivuchakraborty

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Concurrency ● Ability to execute multiple code blocks at the same time ● Not only for Android Developers ● JavaScript - Promise ● JVM, Android - Threads @rivuchakraborty

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10 Concurrency in Android and/or JVM ● AsyncTask (Android only) ● CompletableFuture (Android - API 24+, JVM 1.8) ● Runnable / Thread (Custom Threadpool) ● Rx ● Counting... @rivuchakraborty

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11 Concurrency in Android ● Runnable / Thread @rivuchakraborty

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12 Concurrency in Android ● Rx @rivuchakraborty

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13 Concurrency in Android ● Rx @rivuchakraborty If you’re using Rx only for concurrency, sorry pal, you’re doing it wrong.

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14 ● Coroutines @rivuchakraborty Let’s you write non-blocking asynchronous code in your choice of Style - Sequentially, in Functional Style or whatever you prefer.

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15 ● Coroutines @rivuchakraborty Let’s you write non-blocking asynchronous code in your choice of Style - Sequentially, in Functional Style or whatever you prefer. A Language level feature, managed by the Kotlin team itself.

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16 ● Coroutines @rivuchakraborty ● Let’s you write non-blocking asynchronous code in your choice of Style - Sequentially, in Functional Style or whatever you prefer. ● A Language level feature, managed by the Kotlin team itself. You can add Coroutines dependency to your Kotlin project by following the instructions in GitHub ReadMe - https://github.com/kotlin/kotlinx.coroutines/blob/master/README.md#u sing-in-your-projects

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Coroutines 17 @rivuchakraborty Light-Weight Threads Thread 1 Thread 2 Thread 3 Coroutine 1 Coroutine 2 Coroutine 3 With Coroutines, Threads are still used (for JVM).

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Coroutines 18 @rivuchakraborty Light-Weight Threads Thread 1 Thread 2 Thread 3 Coroutine 1 Coroutine 2 C 3 C 4 C 5 C 6 C 7 C 8 C N But a single Thread can run multiple coroutines.

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Coroutines 19 @rivuchakraborty Easy to Use

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Suspension & Continuation Builders Suspending Functions End Coroutines Components Scope & Dispatchers @rivuchakraborty

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Coroutines 21 @rivuchakraborty Suspending vs Blocking

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Coroutines 22 @rivuchakraborty Suspending vs Blocking

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Coroutines 23 @rivuchakraborty Suspending vs Blocking

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Coroutines 24 @rivuchakraborty Suspending vs Blocking

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Launch a Coroutine 25 @rivuchakraborty

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Get the Job done or cancel it, your choice. :) 26 @rivuchakraborty

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Compute Async(hrounously) 27 @rivuchakraborty

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Deferred 28 @rivuchakraborty ● Deferred Extends Job ● Wrapper around your data

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Suspending Function 29 @rivuchakraborty ● suspend is a Keyword in Kotlin

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Suspending Function 30 @rivuchakraborty ● suspend is a Keyword in Kotlin ● Compiler level restriction - can’t call suspend function outside CoroutineScope

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Suspending Function 31 @rivuchakraborty ● suspend is a Keyword in Kotlin ● Compiler level restriction - can’t call suspend function outside CoroutineScope ● Suspends execution of current coroutine

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Coroutine Scope 32 @rivuchakraborty ● Container of CoroutineContext

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Coroutine Scope 33 @rivuchakraborty ● Container of CoroutineContext ● Every Coroutine Builder is an extension over CoroutineScope, and thus inherits its CoroutineContext

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Coroutine Scope 34 @rivuchakraborty ● Container of CoroutineContext ● Every Coroutine Builder is an extension over CoroutineScope, and thus inherits its CoroutineContext ● All Coroutines must be launched within a CoroutineScope

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Coroutine Scope 35 @rivuchakraborty

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Dispatchers 36 @rivuchakraborty ● Determines which Thread / ThreadPool, the coroutine will run on. ● Similar to the Rx Schedulers

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Let’s Build for Android

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Repository 38 @rivuchakraborty

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API (Retrofit) 39 @rivuchakraborty

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Activity 40 @rivuchakraborty

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Call it 41 @rivuchakraborty

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Handle Exception (Gracefully) :) 42 @rivuchakraborty

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Rivu Chakraborty @rivuchakraborty Resources https://caster.io/courses/kotlin-coroutines-fundamental s ● http://bit.ly/CodeLabCoroutines (Codelab) ● http://bit.ly/CoroutinesAndroid (Article) ● http://bit.ly/DroidCoroutines (Book, yet to be published) ● http://bit.ly/CoroutinesGuide (Official Guide) ● https://www.meetup.com/BlrKotlin/ (Bangalore Kotlin User Group) 43

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Rivu Chakraborty @rivuchakraborty Thank you! 44