Kotlin Coroutines and Flow.

코틀린 코루틴과 플로우에 대한 설명을 포함

Transcript

1. Coroutines
   Taehwan
   

   View Slide

2. য়ט ঌইࠅ ղਊ
   • ࢎਊߨ਷ ݒ਋ рױ೤פ׮.
   
   • ࢎਊߨࠁױ ղࠗ ௏٘ܳ ా೧ ௏ܖ౯ਸ ઑӘ ؊ ࢓ಝࠇפ׮.
   
   • ҃೷࢚ ԙ ঌইفݶ જਸ ղਊਸ ୶о೤פ׮.
   

   View Slide

3. Subroutine
   

   View Slide

4. Subroutine
   • In computer programming, a subroutine is a sequence of program
   instructions that performs a speci
   fi
   c task, packaged as a unit
   
   • In di
   ff
   erent programming languages, a subroutine may be called a
   procedure, a function, a routine, a method, or a subprogram. The generic
   term callable unit is sometimes used.
   

   View Slide

5. Subroutine
   fun runTest() fun MutableList.sum()
   mutableList().sum()
   return sumValue
   +1
   
   
   +2
   
   
   .
   
   
   .
   
   
   .
   

   View Slide

6. Coroutines
   

   View Slide

7. Coroutines
   • According to Donald Knuth, Melvin Conway coined the term coroutine in
   1958 when he applied it to construction of an assembly program.
   
   • The
   fi
   rst published explanation of the coroutine appeared later, in 1963
   

   View Slide

8. Coroutines
   • Coroutines are computer-program components that
   generalize subroutines for non-preemptive multitasking, by allowing
   multiple entry points for suspending and resuming execution at certain
   locations.
   
   • Coroutines are well-suited for implementing familiar program components
   such as cooperative tasks, exceptions, event loops, iterators, in
   fi
   nite
   lists and pipes.
   ୹୊ : https://en.wikipedia.org/wiki/Coroutine
   

   View Slide

9. Coroutines
   Run routine fun Int.sum()
   Loop
   fun Int.sum()
   Loop
   fun Int.sum()
   Loop
   fun Int.sum()
   Loop
   10.sum()
   .
   
   .
   
   .
   Entry point ৈ۞ ѐ ೲਊ
   

   View Slide

10. Kotlin Coroutines
    

    View Slide

11. Kotlin Coroutines
    • Asynchronous or non-blocking programming is an important part of the
    development landscape. When creating server-side, desktop, or mobile
    applications, it's important to provide an experience that is not only
    fl
    uid
    from the user's perspective, but also scalable when needed.
    
    • Kotlin solves this problem in a
    fl
    exible way by providing coroutine support
    at the language level and delegating most of the functionality to libraries.
    
    • In addition to opening the doors to asynchronous programming,
    coroutines also provide a wealth of other possibilities, such as
    concurrency and actors.
    

    View Slide

12. Kotlin Coroutines
    Default :
    dependencies {
    implementation(“org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.1”)
    }
    Android :
    dependencies {
    implementation(“org.jetbrains.kotlinx:kotlinx-coroutines-android:1.5.1”)
    }
    repository {
    mavenCentral()
    }
    Androidীࢲח dependencies ࢎਊ द coroutines-androidܳ ӝࠄਵ۽ ഝਊೞݶ ؾפ׮. উ٘۽੉٘৬ ޖҙೠ ݽٕ۽ ഝਊೡ Ѫ੉ۄݶ
    coroutines-coreܳ ഝਊೞݶ ؾפ׮.
    

    View Slide

13. Kotlin Coroutines
    class MainViewModel : ViewModel() {
    init {
    viewModelScope.launch(Dispatchers.IO) {
    Log.i("TEMP", getMessage())
    }
    Log.i("TEMP", "Hello")
    }
    private suspend fun getMessage(): String {
    delay(1_000L)
    return "World!"
    }
    }
    AAC-ViewModelਸ ഝਊೡ ҃਋੄ ௏ܖ౯ ࢎਊߨ੉ݴ, launch ز੘द ࢎਊೡ ӝࠄ झா઴۞ܳ Dispatchersਸ IO۽ ߸҃೤פ׮.
    

    View Slide

14. Kotlin Coroutines
    public val ViewModel.viewModelScope: CoroutineScope
    get() {
    val scope: CoroutineScope? = this.getTag(JOB_KEY)
    if (scope != null) {
    return scope
    }
    return setTagIfAbsent(
    JOB_KEY,
    CloseableCoroutineScope(SupervisorJob() + Dispatchers.Main.immediate)
    )
    }
    internal class CloseableCoroutineScope(context: CoroutineContext) : Closeable, CoroutineScope {
    override val coroutineContext: CoroutineContext = context
    override fun close() {
    coroutineContext.cancel()
    }
    }
    AAC-ViewModel੄ ഛ੢ ೣࣻ۽ viewModelScope੄ ղࠗ ௏٘ੑפ׮. CoroutineScopeਸ ղࠗ੸ਵ۽ ࢎਊೞҊ, cancel दఃӝ ਤೠ
    Closable ࢚ࣘ ௿ېझо ҳഅغয ੓णפ׮. AAC-ViewModel destroy द ೣԋ ઙܐೞب۾ ٜ݅যઉ੓Ҋ, SupervisorJob()җ Mainਸ ӝ
    ࠄਵ۽ ࢎਊ೤פ׮.
    

    View Slide

15. ੉ ௏٘۽ ঌইࠅ ղਊ
    • CoroutinesScope(GlobalScope਷ ૑ন)
    
    • Coroutines ز੘ೞӝ ਤೠ launch
    
    • CoroutineContext(SupervisorJob, Dispatchers)
    
    • suspend function
    
    • Coroutine ઙܐ ୊ܻ
    

    View Slide

16. CoroutinesScope
    

    View Slide

17. CoroutinesScope
    public interface CoroutineScope {
    /**
    * The context of this scope.
    * Context is encapsulated by the scope and used for implementation of coroutine
    builders that are extensions on the scope.
    * Accessing this property in general code is not recommended for any purposes except
    accessing the [Job] instance for advanced usages.
    *
    * By convention, should contain an instance of a [job][Job] to enforce structured
    concurrency.
    */
    public val coroutineContext: CoroutineContext
    }
    CoroutineScope੄ ୭࢚ਤ interface ੿੄ੑפ׮.
    

    View Slide

18. CoroutinesScope ৉ೡ
    • Coroutine ੿੄ܳ ਤೠ Scope ઁҕ
    
    • CoroutineContext ഋకܳ ૑੿
    
    • Default, IO, Android Main
    
    • launch, async ١ਸ ా೧ coroutine प೯ ഋకܳ ੿੄
    

    View Slide

19. Coroutines ز੘ೞӝ ਤೠ launch
    

    View Slide

20. Coroutines ز੘ೞӝ ਤೠ launch
    class MainViewModel : ViewModel() {
    init {
    viewModelScope.launch(Dispatchers.IO) {
    // 생략
    }
    }
    }
    

    View Slide

21. Coroutines ز੘ೞӝ ਤೠ launch
    public fun CoroutineScope.launch(
    context: CoroutineContext = EmptyCoroutineContext,
    start: CoroutineStart = CoroutineStart.DEFAULT,
    block: suspend CoroutineScope.() -> Unit
    ): Job {
    val newContext = newCoroutineContext(context)
    val coroutine = if (start.isLazy)
    LazyStandaloneCoroutine(newContext, block) else
    StandaloneCoroutine(newContext, active = true)
    coroutine.start(start, coroutine, block)
    return coroutine
    }
    launch੄ start ӝࠄ ز੘਷ CoroutineStart.DEFAULT۽ ૊द प೯ਸ ӝࠄਵ۽ ೠ׮.
    
    
    LAZY۽ ߸҃ द return ೠ Jobਸ ੉ਊ೧ lazy start() ೡ ࣻ ੓׮.
    
    
    contextח ߹ب۽ ૑੿ೞ૑ ঋਵݶ EmptyCoroutineContext੉ݴ, newCoroutineContext۽ parent CoroutineScope੄ context৬ ೤
    ࢿೠ׮.
    newCoroutineContext(context)
    start: CoroutineStart = CoroutineStart.DEFAULT,
    context: CoroutineContext = EmptyCoroutineContext,
    : Job
    CoroutineScope.launch
    

    View Slide

22. Coroutines ز੘ೞӝ ਤೠ launch
    • CoroutineScopeਸ प೯ೞӝ ਤೠ launch, async/await ١੉ ੓׮
    
    • launch ࢎਊद ೦࢚ ࢚ਤ Context + ࢜۽਍ Conextܳ ೤୛ newContext() ࢤࢿ
    
    • launch੄ ӝࠄ ز੘਷ ૊द प೯੉׮.
    
    • launch੄ return ч਷ Jobਸ ߈ജ, प೯ Ѿҗܳ ঳Ҋ र׮ݶ async/await ഝਊ
    

    View Slide

23. CoroutineStart
    • DEFAULT : ૊द प೯, ݽٚ ௏ܖ౯਷ DEFAULTо ӝࠄ
    
    • LAZY : וܻӝ प೯, job ё୓ܳ ੉ਊ start()ܳ ഐ୹೧઻ঠ ೠ׮
    

    View Slide

24. Coroutines ز੘ೞӝ ਤೠ launch
    class MainViewModel : ViewModel() {
    init {
    val job = viewModelScope.launch(start = CoroutineStart.LAZY, context = Dispatchers.IO) {
    // 생략
    }
    job.start()
    }
    }
    launchо lazy۽ ز੘ೞӝ ਤ೧ࢲח startী ২࣌ਸ ୶оೞҊ, launch ز੘द ߹ب੄ contextо ೙ਃೞ׮ݶ Dispatchers.IOܳ ૑੿೤פ׮.
    
    
    Lazy दীח jobীࢲ start()ܳ ഐ୹೤פ׮.
    

    View Slide

25. CoroutineContext
    

    SupervisorJob, Dispatchers, Etc
    

    View Slide

26. CoroutineContext
    • CoroutineContextח ௏ܖ౯੄ ز੘, ҙܻܳ ୊ܻೞӝ ਤೠ Contextܳ ઁҕ
    

    View Slide

27. CoroutineContext
    CloseableCoroutineScope(SupervisorJob() + Dispatchers.Main.immediate)
    Job Dispatchers
    CoroutinesContextח + ো࢑ਵ۽ ੉যࠢ੉ӝ оמ
    

    View Slide

28. Dispatchers
    • Default : JVM झۨ٘ shared pool ӝળਵ۽ ز੘, CPU ௏য ࣻ৬ زੌೞ૑݅ ୭
    ࣗ 2ѐܳ ࢎਊ ( RxJava : Schedulers.computation() )
    
    • IO : Thread ҕਬ ಽ۽ ز੘ ( RxJava : Schedulers.io() )
    
    • Main : Android UI ୊ܻ ( RxJava : Android.main )
    
    • Uncon
    fi
    ned : ౠ੿ झۨ٘ী ઁೠغ૑ ঋח ௏ܖ౯
    

    View Slide

29. Job
    • Job() : ೞա੄ ੘স੉ۄب લਵݶ ੹୓ ઙܐ
    
    • SupervisorJob() : ೞա੄ ੘স੉ ઙܐغযب ׮ܲ ੘স(child/parent)ী ৔ೱਸ ޷
    ஖૑ ঋ਺
    

    View Slide

30. Job
    

    View Slide

31. Job
    • ӝࠄ ؀ӝ
    
    • join() : scope ز੘੉ ՘զ ٸө૑ ؀ӝೞݴ, CoroutinScope উীࢲ ഐ୹ оמ
    
    • प೯
    
    • start() : Scope ࢚కܳ ഛੋೞݴ, ই૒ द੘ೞ૑ ঋওਸ ҃਋ start
    
    • ஂࣗ
    
    • cancelAndJoin() : ઙܐ റ ઙܐ ؀ӝ
    
    • cancel() : ੘স ઺ੋ ز੘ਸ ઙܐ ਬب
    
    • cancelChildren() : Children ੟ী ؀ೠ ઙܐ ਬب
    

    View Slide

32. CoroutineName
    • ز੘ ઺ੋ Coroutine ੉ܴਸ ૑੿ೡ ࣻ ੓׮
    .launch(CoroutineName("Name"))
    

    View Slide

33. CoroutineExceptionHandler
    • CoroutineExceptionHandler
    
    • CoroutinesScope੉ о૑ݶ ݽٚ ೞਤ job ٜ੄ Exceptionਸ ҙܻ
    
    • launchо о૑ݶ launch ੘স ߂ ೞਤ job ٜ੄ exceptionਸ ҙܻ
    
    • try/catch or kotlin.runCatching ࢎਊ द ૒੽ ҙܻೠ׮ח ੄޷
    

    View Slide

34. CoroutineContext
    @Test
    fun test() = runBlocking {
    val coroutineException = CoroutineExceptionHandler { coroutineContext, throwable ->
    val name = coroutineContext[CoroutineName.Key]
    println("name $name + throwable ${throwable.message}")
    }
    val job = CoroutineScope(Dispatchers.IO).launch(coroutineException + CoroutineName("Name")) {
    kotlin.runCatching {
    throw Exception("runCatching")
    }.onFailure {
    println("throwable runCatching ${it.message}")
    }
    throw Exception("Out")
    }
    job.join()
    }
    coroutineExceptionਸ launchী ನೣೞҊ, CoroutineNameਸ ૑੿ೞ৓णפ׮. coroutineExceptionীࢲח CoroutineNameਵ۽ যځ
    ೠ ز੘ীࢲ য়ܨо ߊࢤೞ৓ח૑ ҳ࠙ೡ ࣻ ੓ѱ ؾפ׮.
    
    
    runCatchingਸ ࢎਊೞݶ ૒੽ য়ܨܳ ҙܻೣਸ ڷೞҊ, ݅ড ҕా੄ য়ܨܳ ୶о۽ ੟ইঠ ೠ׮ݶ throwܳ ୶о۽ ߊࢤदఃݶ ؾפ׮.
    

    View Slide

35. CoroutineContext
    public interface CoroutineContext {
    public operator fun plus(context: CoroutineContext): CoroutineContext =
    if (context === EmptyCoroutineContext) this else // fast path -- avoid lambda creation
    context.fold(this) { acc, element ->
    val removed = acc.minusKey(element.key)
    if (removed === EmptyCoroutineContext) element else {
    // make sure interceptor is always last in the context (and thus is fast to get when present)
    val interceptor = removed[ContinuationInterceptor]
    if (interceptor == null) CombinedContext(removed, element) else {
    val left = removed.minusKey(ContinuationInterceptor)
    if (left === EmptyCoroutineContext) CombinedContext(element, interceptor) else
    CombinedContext(CombinedContext(left, element), interceptor)
    }
    }
    }
    }
    CoroutineContext੄ ղࠗ ௏٘ ઺ plus ࠗ࠙ੑפ׮.
    

    View Slide

36. suspend function
    

    View Slide

37. suspend function
    • suspend ఃਕ٘ܳ ୶оೞৈ ೣࣻ ࠙ೡ
    
    • suspend ೣࣻח CoroutineScope ղীࢲ ࢎਊ оמ
    

    View Slide

38. suspend function ٣ஹ౵ੌ
    private final Object getMessage(Continuation $completion) {
    return "World!";
    }
    private open class StandaloneCoroutine(
    parentContext: CoroutineContext,
    active: Boolean
    ) : AbstractCoroutine(parentContext, initParentJob = true, active = active)
    public abstract class AbstractCoroutine(
    parentContext: CoroutineContext,
    initParentJob: Boolean,
    active: Boolean
    ) : JobSupport(active), Job, Continuation, CoroutineScope
    suspend function੄ ٣ஹ౵ੌ ௏٘ח getMessage() ࠗ࠙ੑפ׮. suspendܳ ನೣೡ ҃਋ Continuationਸ ౵ۄ޷ఠ۽ ߉חؘ, ੉۽ ੋ೧
    CoroutineScope ղীࢲ ௏٘о प೯غযঠ ೣਸ ੄޷೤פ׮. launch੄ ղࠗ ௏٘ܳ ୶੸೧ࠁݶ StandaloneCoroutine ղࠗ੄
    AbstractCoroutine੉ ੓Ҋ, ೠ ߣ ؊ ୶੸ೞݶ Continuationܳ ࢚ࣘ߉Ҋ ੓਺ਸ ഛੋ೧ࠅ ࣻ ੓णפ׮. * ٣ஹ౵ੌ Ѿҗח ׳ۄ૕ ࣻ ੓
    ਵפ ױࣽ ଵҊ݅ ೞࣁਃ.
    

    View Slide

39. suspend function
    public interface Continuation {
    /**
    * The context of the coroutine that corresponds to this continuation.
    */
    public val context: CoroutineContext
    /**
    * Resumes the execution of the corresponding coroutine passing a successful or failed [result] as the
    * return value of the last suspension point.
    */
    public fun resumeWith(result: Result)
    }
    suspend ٣ஹ౵ੌ द ֢୹ػ Continuation interfaceח resumeWith()ਸ ನೣ೤פ׮. Continuationীࢲ ੉੹ਵ۽ ࠂӈೡ ٸח
    resumeWith()ਸ ഐ୹೧ чਸ ֈѹ઱ݶ ੉੹੄ ࢚క۽ جইцפ׮.
    

    View Slide

40. Coroutine ઙܐ ୊ܻ
    

    View Slide

41. Coroutine ઙܐ ୊ܻ
    • ઙܐ ୊ܻ ߑߨ
    
    • Coroutine ୡӝച दী ੸ਊೠ Job ژח CoroutineContext ੉ਊೠ ઙܐ
    
    • пп੄ launch੄ return jobਸ ੉ਊೠ ઙܐ
    
    • ઙܐೞ૑ ޅೞח ࢚ട
    
    • for ܖ೐ীࢲח ௏ܖ౯ cancel()ਸ ೞ؊ۄب ઙܐೞ૑ ޅೠ׮ (׮਺੢ ଵઑ)
    
    • ܖ೐ীࢲ ௏ܖ౯ ઙܐܳ ਤೠ ߹ب੄ ୊ܻ ೙ਃ
    

    View Slide

42. Coroutine ઙܐ ୊ܻ
    @Test
    fun testList() = runBlocking {
    val scope = CoroutineScope(Dispatchers.IO)
    val job = scope.launch {
    (0..1_000).forEach {
    println("data $it")
    }
    }
    scope.launch {
    delay(5)
    println("Call cancel”)
    job.cancel()
    }
    job.join()
    println("run!")
    }
    data 0
    data 1
    …
    data 33
    Call cancel
    data 34
    …
    data 1000
    run!
    ੉ ௏٘ח forEach {}۽ 0ࠗఠ 1_000ө૑ ܖ೐ܳ ز੘೤פ׮. 5ms റ cancel()ਸ ೮૑݅ Ѿҗח data 1000ө૑ ݽف ୹۱ റ ઙܐؾפ׮.
    
    
    ੉ ௏٘ח cancel()ਸ ೞ؊ۄب ઙܐೡ ߑߨ੉ হणפ׮.
    

    View Slide

43. Coroutine ઙܐ ୊ܻ - isActive ࢚క۽ ഛੋ
    @Test
    fun testList() = runBlocking {
    val scope = CoroutineScope(Dispatchers.IO)
    val job = scope.launch {
    (0..1_000).forEach {
    if (isActive) {
    println("data $it")
    } else {
    cancel()
    }
    }
    }
    scope.launch {
    delay(5)
    println("Call cancel")
    job.cancel()
    }
    job.join()
    println("run!")
    }
    data 0
    data 1
    …
    data 82
    Call cancel
    data 83
    …
    data 104
    run!
    cancel੉ ز੘ೞѱ ٜ݅۰ݶ isActive ࢚కܳ ୓௼ೞҊ, ੉ܳ ੿૑ೡ ࣻ ੓ب۾ ୶о ੘স੉ ೙ਃ೤פ׮. ੉ ࢠ೒ীࢲח isActive ࢚కо ইפۄ
    ݶ cancel()ਸ ୊ܻ೤פ׮.
    
    
    forEach {} ղী cancel()ਸ ୶оೞ৓ӝী, 0~1_000ө૑о ইצ 5ms റ ઙܐ೤פ׮.
    

    View Slide

44. Coroutine ઙܐ ୊ܻ - asFlow, cancellable
    @Test
    fun testList() = runBlocking {
    val scope = CoroutineScope(Dispatchers.IO)
    val job = scope.launch {
    (0..1_000).asFlow().cancellable().collect {
    println("data $it")
    }
    }
    scope.launch {
    delay(5)
    println("Call cancel")
    job.cancel()
    }
    job.join()
    println("run!")
    }
    data 0
    data 1
    …
    data 31
    Call cancel
    data 32
    …
    data 40
    run!
    asFlow()۽ ߸҃ೞҊ, cancellable()ਸ ୊ܻೞח ߑߨب ੓णפ׮. ੉ ࠗ࠙਷ ޙࢲী ੜ ա৬੓ਵפ ޙࢲܳ ଵҊೞࣁਃ.
    

    View Slide

45. Flow
    

    View Slide

46. Flow
    • Flow : ColdFlow
    
    • чਸ ࣽର੸ਵ۽ ൗ۰ࠁմ׮.
    
    • collect {}ਸ ೧ঠ ز੘
    
    • map,
    fi
    lter, take, zip ١җ э਷ ൒ܴ੄ ઺р ো࢑੗ܳ ઁҕ
    

    View Slide

47. Flow
    @Test
    fun testFlow() = runBlocking {
    flow {
    (1..100).forEach {
    emit(it)
    }
    }
    .filter { it < 50 }
    .flowOn(Dispatchers.IO)
    .collect {
    println("data $it")
    }
    }
    fl
    ow ࢠ೒ ௏٘۽ 1ࠗఠ 100ө૑ ܖ೐ܳ ز੘ೞҊ, ࣽࢲ؀۽
    fi
    lter৬ collect{}ীࢲ ୹۱ೞח ௏٘ੑפ׮.
    

    View Slide

48. Flow + combine
    @Test
    fun testFlowZip() = runBlocking {
    val flowTest = flow {
    (1..10).forEach {
    emit(it)
    }
    }
    flowOf(2).combine(flowTest) { a, b ->
    a * b
    }
    .collect {
    println("it $it")
    }
    }
    fl
    owOf۽ ೦࢚ 2৬ combineਵ۽
    fl
    owTest੄ 1ࠗఠ 10ө૑੄ чਸ ൗ۰ղ݀פ׮. ੉ٸ a * bܳ ୊ܻ೤פ׮.
    

    View Slide

49. Flow
    •
    fl
    owח
    fl
    ow {} উীࢲ emit ೧ঠ ೠ׮. (RxJava create)
    
    •
    fl
    owOf()ח 1ഥ ࢿ ؘ੉ఠী ഝਊೡ ࣻ ੓׮. (RxJava just)
    
    •
    fl
    owOn੄ ز੘਷ Dispatcher ੸ਊҗ زदী ׮਺
    fl
    owOn੉ য়ӝ ੹ө૑ زੌೠ झ
    ா઴۞ীࢲ ز੘ೠ׮. (RxJava subscribeOn, observeOn)
    
    • Collect ೣࣻח suspend function੉ݴ, CoroutineScope ղীࢲ ز੘ೠ׮.
    (RxJava subscribe)
    
    • Error ୊ܻח Coroutineীࢲ ࢎਊೞ؍ ߑधҗ زੌ(try/catch or
    CoroutineExceptionHandler)
    

    View Slide

50. Callback ؘ੉ఠܳ Flow۽
    • ৻ࠗ CallbackEventܳ Flow۽ ੹ജೞח ߑߨ
    
    • callbackFlowܳ ഝਊ
    
    • ଵҊ ੗ܐ
    
    • https://thdev.tech/kotlin/2020/12/07/Coroutines-Flow-Callback/
    
    • https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/
    kotlinx.coroutines.
    fl
    ow/callback-
    fl
    ow.html
    

    View Slide

51. Callback ؘ੉ఠܳ Flow۽
    class FlowMotionEvent {
    fun createMotionEvent(event: View): Flow = callbackFlow {
    val callback = View.OnTouchListener { _, p1 ->
    trySendBlocking(p1)
    true
    }
    event.setOnTouchListener(callback)
    awaitClose {
    event.setOnTouchListener(null)
    }
    }
    }
    awaitClose ೙ࣻ
    ௏٘ blocking হח ҃਋ী݅!
    

    View Slide

52. Callback ؘ੉ఠܳ Flow۽
    public fun SendChannel.trySendBlocking(element: E): ChannelResult {
    /*
    * Sent successfully -- bail out.
    * But failure may indicate either that the channel it full or that
    * it is close. Go to slow path on failure to simplify the successful path and
    * to materialize default exception.
    */
    trySend(element).onSuccess { return ChannelResult.success(Unit) }
    return runBlocking {
    val r = runCatching { send(element) }
    if (r.isSuccess) ChannelResult.success(Unit)
    else ChannelResult.closed(r.exceptionOrNull())
    }
    }
    trySendBlocking੄ ղࠗ ௏٘ীࢲ ঌ ࣻ ੓૑݅ runBlockingਸ ഝਊೞҊ ੓णפ׮. runBlocking਷ UIী ؀ೠ lock੉ ߊࢤೡ ࣻ ੓ӝ ٸޙ
    ী trySendBlocking ௏٘੄ ࢎਊ द UI৬ ޖҙೠ Ҕীࢲ ࢎਊ੉ ೙ਃೞפ ઱੄೧ࢲ ࢎਊ೧ঠ ೤פ׮.
    

    View Slide

53. SharedFlow
    

    View Slide

54. SharedFlow
    • SharedFlow
    
    • HotFlow
    
    • Broadcast ߑधਵ۽ ؘ੉ఠܳ ҕਬ
    
    • ҕਬ ൒ܴ਷ ഝࢿ ੋझఢझо collect৬ ة݀੸ਵ۽ ઓ੤
    

    View Slide

55. MutableSharedFlow
    • ৈ۞ Ҕীࢲ ਽׹ਸ ߉ইঠ ೡ ҃਋ ਬਊ
    
    • replay(0), extraBu
    ff
    erCapacity(0), Bu
    ff
    erOverFlow(Suspend) ࢚కܳ Ѿ੿ оמ
    
    • launchInਸ ݃૑݄ী ੸য઱য collect{} হ੉ ز੘ оמ
    

    View Slide

56. MutableSharedFlow - ClickEvent
    private val mutableSharedFlow = MutableSharedFlow(
    extraBufferCapacity = 1,
    onBufferOverflow = BufferOverflow.DROP_OLDEST
    )
    init {
    mutableSharedFlow
    .onEach {
    Log.e("TEMP", "clickCount $it")
    }
    .flowOn(Dispatchers.Main)
    .launchIn(viewModelScope)
    }
    private var count = 0
    fun clickEvent() {
    mutableSharedFlow.tryEmit(count++)
    }
    MutableSharedFlowܳ ੉ਊೠ clickEvent ୊ܻ ࠗ࠙ੑפ׮. ௿ܼ ੉߮౟ח extraBufferܳ 1ѐܳ ୶оೞҊ, Over
    fl
    owܳ Drop oldest۽
    ୊ܻ೧ સפ׮.
    
    
    tryEmit()ਵ۽ countܳ োࣘ੸ਵ۽ ֈӝחؘ, 0, 1, 2, …ਸ ୊ܻ೤פ׮.
    

    View Slide

57. MutableSharedFlow - ClickEvent
    public fun Flow.launchIn(scope: CoroutineScope): Job = scope.launch {
    collect() // tail-call
    }
    ଵҊ۽ launchIn੄ ղࠗ ௏٘ੑפ׮. ֈѹ߉਷ scopeਸ ੉ਊ೧ launchܳ ୊ܻೞҊ, collect()ਸ ഐ୹೤פ׮.
    

    View Slide

58. StateFlow
    

    View Slide

59. StateFlow
    • ݃૑݄ ࢚క чਸ ӝর೧ঠ ೡ ҃਋ ਬਊ
    
    • ୡӝച чਸ ೣԋ ֈѹঠ ೠ׮
    
    • زੌೠ ч਷ ޖदೠ׮
    
    • ੑ۱ೠ ч਷ Read-only۽ ز੘ೠ׮
    

    View Slide

60. StateFlow
    private val stateFlow = MutableStateFlow(true)
    init {
    stateFlow
    .onEach {
    Log.e("TEMP", "value change $it")
    }
    .flowOn(Dispatchers.IO)
    .launchIn(viewModelScope)
    }
    fun clickEvent() {
    stateFlow.value = stateFlow.value.not()
    }
    MutableStateFlow۽ ୡӝച чਸ ೣԋ ֈѹસפ׮. StateFlowח زੌೠ ч੉ 1ഥ ੉࢚ ٜযয়ݶ ղࠗ੸ਵ۽ ޖदೞѱ ؾפ׮.
    
    
    ੉ ௏٘ীࢲ trueܳ 1ߣ ੉࢚ ֈӝݶ ୐ ߣ૩ value݅ streamਵ۽ ղ۰оҊ, ف ߣ૩ trueח ޖद೤פ׮.
    

    View Slide

61. Coroutines Flow test
    
    
    Turbin
    

    View Slide

62. Coroutines Flow test
    https://github.com/cashapp/turbine
    testImplementation("app.cash.turbine:turbine:0.5.2")
    Flow పझ౟ܳ ਤೠ turbineਸ ഝਊೡ ࣻ ੓णפ׮.
    

    View Slide

63. Coroutines Flow test
    @OptIn(ExperimentalTime::class)
    @Test
    fun test() = runBlocking {
    flowOf("one", "two").test {
    Assert.assertEquals("one", expectItem())
    Assert.assertEquals("two", expectItem())
    expectComplete()
    }
    }
    test{}ח runBlocking {} উীࢲ ഐ୹೧ঠ ೞݴ,
    fl
    ow੄ ҃਋ ೦࢚ expectComplete()ܳ ഐ୹೧ ઱যঠ ೤פ׮.
    

    View Slide

64. Coroutines SharedFlow test
    @ExperimentalTime
    @Test
    fun testSharedFlow() = runBlocking {
    val mutableSharedFlow = MutableSharedFlow(replay = 0)
    mutableSharedFlow.emit(1)
    mutableSharedFlow.test {
    Assert.assertEquals(expectItem(), 1)
    cancelAndConsumeRemainingEvents()
    }
    }
    MutableSharedFlowب turbinਸ ഝਊೡ ࣻ ੓णפ׮. SharedFlow੄ ҃਋ ݃૑݄ী cancelAndConsumeRemainingEvents()ܳ ഐ୹
    ೧ঠ ઙܐо ؾפ׮.
    

    View Slide

65. RxJava > Flow or Coroutines
    

    View Slide

66. RxJava vs Flow
    RxJava Flow
    ੿੄ Flowable, Observable, Single ١
    fl
    ow, SharedFlow, StateFlow
    ੹୓ झாે۞ ૑੿ subscribeOn(schedulers.io())
    fl
    owOnী ٮۄ ز੘
    झாે۞ ߸҃ observeOn(schedulers.io())
    fl
    owOn(CoroutineContext)
    झாે۞ ߧਤ observeOnীࢲ ੿੄ೠ ׮਺ࠗఠ ݽف ੸ਊ ׮਺
    fl
    owOn੄ ੿੄о য়ӝ ੹ө૑ زੌೞѱ ୊ܻ
    द੘ subscribe ੿੄о ੓যঠ ز੘
    collectী ٮۄ ز੘
    
    CoroutineScope ղীࢲ ز੘
    

    View Slide

67. RxJava > Flow or Coroutines
    • RxJava੄ ௏٘ܳ ׼੢ ѥযղӝ য۵׮ݶ Coroutines rx2
    
    • https://github.com/Kotlin/kotlinx.coroutines/tree/master/reactive/
    kotlinx-coroutines-rx2
    
    • ӝઓ Repository੄ RxJavaܳ ߸҃ೠ׮ݶ Flowܳ ࢎਊ೧ ߸҃ оמ
    

    View Slide