Kotlin Multiplatform Architecture

Discussing building shared architecture apps with Kotlin, mostly native mobile (Android & iOS). Talk about libraries currently available, why Jetbrains has a different threading model, where the ecosystem is at and where I think it's going.

Transcript

1. Kotlin Multiplatform Architecture Kevin Galligan
3. Touchlab
4. Community community!
6. SHARED ARHICTECTURE
7. Mobile & Web Architecture, not UI
8. Shared UI == Failure!
9. Shared Loigc == Computers
11. Web is more difficult No SQL :(
12. Advocate for new standards I want SQL again
13. https://hacks.mozilla.org/
14. mobile is MUCH simpler
15. Why Kotlin?
17. Modern Language
19. Community Excitement
20. Best Tools
21. Smooth Interop
22. Optional Sharing Low risk. No Big Decisions.
23. “Everything Should Be Made as Simple as Possible, But Not Simpler” - Albert Einstein Maybe?
24. Status
25. Q3 Q2 Q4 Q1 Q2 2018 2019 0 .6 v0.7 v0.8 v0.8.2 v0.9.3 IDE tooling! Coroutines?
26. Q3 Q2 Q4 Q1 Q2 2018 2019 0 .6 v0.7 v0.8 v0.8.2 v0.9.3 IDE tooling! Coroutines? K/N 1.0, Kotlin 1.3 Gradle 4.10+ Android Studio
27. Q3 Q2 Q4 Q1 Q2 2018 2019 0 .6 v0.7 v0.8 v0.8.2 v0.9.3 IDE tooling! Coroutines? K/N 1.0, Kotlin 1.3 Gradle 4.10+ Android Studio MT Coroutines! Other samples/libraries Production deployments
28. Q3 Q2 Q4 Q1 Q2 2018 2019 0 .6 v0.7 v0.8 v0.8.2 v0.9.3 IDE tooling! Coroutines? K/N 1.0, Kotlin 1.3 Gradle 4.10+ Android Studio MT Coroutines! Other samples/libraries Production deployments Paid license/debugger Reactive Library Big Production Apps Webassembly stuff?
29. SHARED CODE FOR ANDROID & IOS
30. Common
31. Common mainThread?
32. expect val mainThread:Boolean
33. expect val mainThread:Boolean actual val mainThread: Boolean get() = Looper.myLooper() === Looper.getMainLooper()
34. expect val mainThread:Boolean actual val mainThread: Boolean get() = Looper.myLooper() === Looper.getMainLooper() actual val mainThread: Boolean get() = NSThread.isMainThread()
35. expect val mainThread:Boolean actual val mainThread: Boolean get() = Looper.myLooper() === Looper.getMainLooper() actual val mainThread: Boolean get() = NSThread.isMainThread() actual val mainThread: Boolean = true
36. expect fun currentTimeMillis():Long expect fun <B> backgroundTask(backJob:()-> B, mainJob:(B) -> Unit) expect fun backgroundTask(backJob:()->Unit) expect fun networkBackgroundTask(backJob:()->Unit) expect fun initContext():NativeOpenHelperFactory expect fun <T> goFreeze(a:T):T expect fun <T> T.freeze2(): T expect fun simpleGet(url:String):String expect fun logException(t:Throwable) expect fun settingsFactory(): Settings.Factory expect fun createUuid():String
37. expect class Date { fun toLongMillis():Long } expect class DateFormatHelper(format:String){ fun toDate(s:String):Date fun format(d:Date):String }
38. actual class Date(val date:java.util.Date) { actual fun toLongMillis(): Long = date.time } actual class DateFormatHelper actual constructor(format: String) { val dateFormatter = object : ThreadLocal<DateFormat>(){ override fun initialValue(): DateFormat = SimpleDateFormat(format) } actual fun toDate(s: String): Date = Date(dateFormatter.get()!!.parse(s)) actual fun format(d: Date): String = dateFormatter.get()!!.format(d.date) }
39. fun initPlatformClient( staticFileLoader: (filePrefix: String, fileType: String) -> String?, analyticsCallback: (name: String, params: Map<String, Any>) -> Unit, clLogCallback: (s: String) -> Unit) {
40. fun initPlatformClient( staticFileLoader: (filePrefix: String, fileType: String) -> String?, analyticsCallback: (name: String, params: Map<String, Any>) -> Unit, clLogCallback: (s: String) -> Unit) { AppContext.initPlatformClient ({filePrefix, fileType -> loadAsset("${filePrefix}.${fileType}")}, {name: String, params: Map<String, Any> -> val event = CustomEvent(name) //Loop Answers.getInstance().logCustom(event) }, { Log.w("MainApp", it) })
41. let appContext = AppContext() appContext.doInitPlatformClient(staticFileLoader: loadAsset, analyticsCallback: analyticsCallback, clLogCallback: csLog) func loadAsset(filePrefix:String, fileType:String) -> String?{ do{ let bundleFile = Bundle.main.path(forResource: filePrefix, ofType: fileType) return try String(contentsOfFile: bundleFile!) } catch { return nil } }
42. Common
43. JVM Native Common
44. JVM Native Common Framework
45. JVM Native Common Framework
46. JVM Native Common Android Stuff Framework iOS Stuff
47. JVM Native Common
48. JVM Native Common Ktor-JVM Ktor-Native Ktor
49. More Info and Tutorials https://github.com/touchlab/KotlinMultiplatformStuff
50. DROIDCON WITH KOTLIN MULTIPLATFORM
51. Funky Code Testbed
52. Funky Code Testbed Kotlin in 2014!
53. Droidcon NYC & SF
54. SQLite Knarch.db Android iOS
55. SQLite Knarch.db SQLDelight Android iOS
56. SQLite Knarch.db SQLDelight Logic! Reactive (LiveData) Android iOS
57. SQLite Knarch.db SQLDelight Logic! Reactive (LiveData) Android iOS
58. SQLite Knarch.db SQLDelight MP Settings Logic! Reactive (LiveData) Android iOS
59. val evenLiveData:EventLiveData init { val query = goFreeze(AppContext.dbHelper. queryWrapper.sessionQueries. sessionById(sessionId)) evenLiveData = EventLiveData(query) } fun shutDown(){ evenLiveData.removeListener() }
60. val evenLiveData:EventLiveData init { val query = goFreeze(AppContext.dbHelper. queryWrapper.sessionQueries. sessionById(sessionId)) evenLiveData = EventLiveData(query) } fun shutDown(){ evenLiveData.removeListener() }
61. override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? { eventViewModel.eventModel.evenLiveData. observe(viewLifecycleOwner, Observer { dataRefresh(it) }) return initView(inflater, container) }
62. override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? { eventViewModel.eventModel.evenLiveData. observe(viewLifecycleOwner, Observer { dataRefresh(it) }) return initView(inflater, container) }
63. fun registerForChanges(proc:(sessionInfo:SessionInfo)->Unit){ eventObserver = object : Observer<SessionInfo>{ override fun onChanged(t: SessionInfo?){ if(t != null) proc(t) } } eventModel.evenLiveData.observeForever(eventObserver!!) }
64. viewModel = EventViewModel(sessionId: sessionId) viewModel.registerForChanges(proc: updateUi)
65. viewModel = EventViewModel(sessionId: sessionId) viewModel.registerForChanges(proc: updateUi) func updateUi(sessionInfo:SessionInfo) -> KotlinUnit{ self.sessionInfo = sessionInfo styleButton() updateAllUi() return KotlinUnit() }
66. Droidcon App Kotlin Multiplatform https://www.youtube.com/watch?v=YAeDK3Ei0Lk https://github.com/touchlab/DroidconKotlin/ Now with 0.9.3!
67. KOTLINCONF WITH KOTLIN MULTIPLATFORM (OBV)
68. Settings Android iOS Ktor
69. Settings Android iOS Ktor DataRepository
70. Settings Android iOS Ktor DataRepository SessionDetailsPresenter
71. Settings Android iOS Ktor DataRepository SessionDetailsPresenter SessionDetailsView
72. interface SessionDetailsView : BaseView { fun updateView(isFavorite: Boolean, session: SessionModel) fun setupRatingButtons(rating: SessionRating?) fun setRatingClickable(clickable: Boolean) } override fun updateView(isFavorite: Boolean, session: SessionModel) { collapsingToolbar.title = session.title speakersTextView.text = session.speakers.joinToString(separator = ", ") { it.fullName } timeTextView.text = session.timeString detailsTextView.text = listOfNotNull(session.roomText, session.category).joinToString(", ") descriptionTextView.text = session.descriptionText val online = context?.let { it.isConnected?.and(!it.isAirplaneModeOn) } ?: false for (button in listOf(votingButtonsLayout, favoriteButton)) { func updateView(isFavorite: Bool, session: SessionModel) { titleLabel.text = session.title let startsAt = session.startsAt let endsAt = session.endsAt if (startsAt != nil && endsAt != nil) { timeLabel.text = KotlinPair(first: startsAt, second: endsAt).toReadableString() } let image = UIImage(named: isFavorite ? "star_full" : "star_empty")! favoriteButton.image = image
73. Settings Android iOS Ktor DataRepository SessionDetailsPresenter SessionDetailsView
74. KotlinConf App https://github.com/JetBrains/kotlinconf-app
75. Which?
76. STATE
77. 3 Ecosystems JVM, JS, and Native
78. Kotlin/Native State Rules
79. Rule #1 Live state belongs to 1 thread
80. Rule #2 Frozen state can be shared by threads
81. No threading primitives No “synchronized”, “volatile”, etc
82. Runtime Safety Kotlin/Native can verify safe mutability
83. JVM/JS? See Kotlinconf keynote
84. Short term pain Tradeoff for future
85. How does Kotlin know?!
86. FROZEN!
87. FROZEN!
88. Runtime Designation AKA a flag
89. all the code you’ve ever written not frozen frozen
90. all the code you’ve ever written not frozen frozen
91. One-way operation No unfreeze()
92. Freezes everything
93. class TalkExamples{ var justCountingStuff:Int = 0 init { backgroundCall { //do something justCountingStuff++ }.freeze() } }
94. class TalkExamples{ var justCountingStuff:Int = 0 init { backgroundCall { //do something justCountingStuff++ }.freeze() } }
95. Usually OK Data objects should be immutable
96. Global state more difficult Service object, large memory state
97. Passing State
98. DetachedObjectGraph(TransferMode.SAFE) { ListData("asdf") }
99. val data = ListData("asdf") DetachedObjectGraph(TransferMode.SAFE) { data }
100. private val stateBox: AtomicReference<DetachedObjectGraph<Any>> = AtomicReference( DetachedObjectGraph(mode = TransferMode.SAFE, producer = { mutableListOf<E>() as Any }) ) private val lock = NSLock() internal fun withLockDetached(proc: (MutableList<E>) -> MutableList<E>) { lock.lock() try { stateBox.value = DetachedObjectGraph(mode = TransferMode.SAFE, producer = { val dataList = stateBox.value.attach() as MutableList<E> proc(dataList) as Any }) } finally { lock.unlock() } }
101. Atomics! Mutable immutable
102. AtomicInt/AtomicLong
103. AtomicReference Update with frozen objects
104. val lambdas = AtomicReference<PlatformLambdas?>(null) fun initPlatformClient( staticFileLoader: (filePrefix: String, fileType: String) -> String?, analyticsCallback: (name: String, params: Map<String, Any>) -> Unit, clLogCallback: (s: String) -> Unit) { lambdas.value = PlatformLambdas( staticFileLoader, analyticsCallback, clLogCallback).freeze() }
105. data class FrozenData( val someCount:AtomicInt, val someString:String, val someOtherState:AtomicReference<OtherState> ) data class OtherState( val otherCount:Int, val otherString:String )
106. val frozenData = FrozenData( AtomicInt(1), "asdf", AtomicReference( OtherState( 1, "qwert") ) ).freeze()
107. val frozenData = FrozenData( AtomicInt(1), "asdf", AtomicReference( OtherState( 1, "qwert") ) ).freeze()
108. fun update(frozenData: FrozenData){ frozenData.someCount.increment() val otherState = frozenData.someOtherState.value val updated = otherState.copy(otherCount = otherState.otherCount+1) frozenData.someOtherState.value = updated.freeze() }
109. Stately! v0.3.1~ish
110. Multiplatform Definitions • freeze() method and frozen info • Atomics (Int, Long, Reference) • K/N state-related annotations (@ThreadLocal/ @SharedImmutable)
111. Multithreaded Collections Built on atomics
112. val cowList = frozenCopyOnWriteList<SampleData>() val sharedList = frozenLinkedList<SampleData>() val coiSharedList = frozenLinkedList<SampleData>(stableIterator = true) val sharedMap = frozenHashMap<String, SampleData>() val lruRemovedCount = AtomicInt(0) val lruCache = frozenLruCache<String, SampleData>(5) { lruRemovedCount.increment() }
113. Why? If you have to ask…
115. Changing Architectures Coroutines, libraries, best practices
116. THREADING
117. Workers like Executor
118. Passing State similar to DetachedObjectGraph
119. Until Coroutines MT coroutines will largely replace Worker
120. Coroutines and State? we’ll see
121. LIBRARIES
122. Jetbrains • Ktor • Kotlinx.Coroutines • Kotlinx.io • Atomic-fu
123. Community • Sqldelight • Knarch.db • Multiplatform Settings • Stately • OKIO2 (developing)
124. GETTING STARTED
125. Intellij EAP Sample project templates!
127. Build Samples Conference apps, several others
128. Kotlin/Native Docs Learn threads and state
129. Join the Kotlin Slack
130. Kotlinconf Videos list on KotlinMultiplatformStuff
131. For Libraries? Check out Stately
132. check out yours!
134. kevin@touchlab.co @kpgalligan
135. kevin@touchlab.co @kpgalligan Join the team !