Dissecting Coroutines Library

Transcript

1. Mohit Sarveiya Dissecting Coroutines Library @heyitsmohit
2. Dissecting Coroutines Library • Context • Channels • Flows • Shared Mutable State
3. Dissecting Coroutines Library • Implementation • Use cases
4. Context
5. val scope = CoroutineScope(Dispatchers.IO) scope.launch { }
6. val scope = CoroutineScope(Dispatchers.IO) fun CoroutineScope(context: CoroutineContext)
7. interface CoroutineContext { interface Key<E : Element> interface Element }
8. interface CoroutineContext { interface Key<E : Element> interface Element }
9. interface CoroutineContext { operator fun get(key: Key<E>): E? operator fun plus(context: CoroutineContext): CoroutineContext }
10. interface CoroutineContext { operator fun get(key: Key<E>): E? operator fun plus(context: CoroutineContext) }
11. Context Elements • Job • Coroutine Name • Dispatcher
12. val scope = CoroutineScope( CoroutineName("My Coroutine") + Dispatchers.IO )
13. val scope = CoroutineScope( CoroutineName("My Coroutine") + Dispatchers.IO ) operator fun plus(context: CoroutineContext)
14. val scope = CoroutineScope( CoroutineName("My Coroutine") + Dispatchers.IO ) scope.coroutineContext[CoroutineName]
15. val scope = CoroutineScope( CoroutineName("My Coroutine") + Dispatchers.IO ) scope.coroutineContext[CoroutineName] / / CoroutineName(My Coroutine)
16. val scope = CoroutineScope( CoroutineName("My Coroutine") + Dispatchers.IO ) scope.coroutineContext[ContinuationInterceptor]
17. val job = Job() val scope = CoroutineScope( CoroutineName("My Coroutine") + job + Dispatchers.IO )
18. val job = Job() val scope = CoroutineScope( CoroutineName("My Coroutine") + job + Dispatchers.IO )
19. val job = Job() val scope = CoroutineScope( CoroutineName("My Coroutine") + job + Dispatchers.IO ) scope.coroutineContext[Job] / / JobImpl{Active}
20. Custom Context Use Cases • Dispatcher Provider (Dispatch) • Thread Local (krotoPlus) • Database Transactions (Room)
21. RBusarow/Dispatch Code ! Issues Pull Requests Dispatch Bazel Build passing Gradle Build passing Utilities for kotlinx.coroutines which make them type-safe, easier to test, and more expressive.
22. Scopes • IOScope • DefaultScope • UnDispatchedScope
23. class DefaultDispatcherProvider { val default: CoroutineDispatcher = Dispatchers.Default val io: CoroutineDispatcher = Dispatchers.IO val main: CoroutineDispatcher = Dispatchers.Main }
24. interface DispatcherProvider : CoroutineContext.Element { override val key: CoroutineContext.Key < * > get() = Key companion object Key : CoroutineContext.Key<DispatcherProvider> }
25. fun IOCoroutineScope(dispatcherProvider = DefaultDispatcherProvider()) { override val coroutineContext = job + dispatcherProvider.io + dispatcherProvider }
26. Resources • Custom Coroutine Context Use Cases • Dispatch
27. Channels
28. Coroutine Coroutine Channel
29. Coroutine Coroutine Data Channel
30. interface Channel<E> { suspend fun send(element: E) suspend fun receive(): E } Channel
31. Channel Types • Rendezvous • Buffered • Unlimited
32. fun <E> Channel(capacity: Int = RENDEZVOUS) = when (capacity) { RENDEZVOUS - > RendezvousChannel() UNLIMITED - > LinkedListChannel() CONFLATED - > ConflatedChannel() BUFFERED - > ArrayChannel(CHANNEL_DEFAULT_CAPACITY) else - > ArrayChannel(capacity) }
33. Channel Types • Rendezvous • Buffered • Unlimited
34. runBlocking { 
 val channel = Channel<Int>() launch { channel.send(1) } val num = channel.receive() }
35. runBlocking { 
 val channel = Channel<Int>() launch { channel.send(1) } val num = channel.receive() }
36. runBlocking { 
 val channel = Channel<Int>() launch { channel.send(1) } val num = channel.receive() }
37. runBlocking { 
 val channel = Channel<Int>() launch { channel.send(1) } val num = channel.receive() } SUSPEND
38. runBlocking { 
 val channel = Channel<Int>() launch { channel.send(1) } val num = channel.receive() }
39. Channel Types • Rendezvous • Buffered • Unlimited
40. runBlocking { 
 val channel = Channel<Int>(10) launch { channel.send(1) } val num = channel.receive() }
41. runBlocking { 
 val channel = Channel<Int>(10) launch { channel.send(1) channel.send(2) channel.send(3) } }
42. Channel Types • Rendezvous • Buffered • Unlimited
43. runBlocking { 
 val channel = Channel<Int>(Channel.UNLIMITED) launch { channel.send(1) channel.send(2) channel.send(3) } }
44. runBlocking { 
 val channel = Channel<Int>(Channel.UNLIMITED) launch { channel.send(1) channel.send(2) channel.send(3) } }
45. Channel Types • Rendezvous • Buffered • Unlimited
46. Papers
47. Channel State • Queue • Optional Buffer
48. Channel Queue States • Empty • Send Queued • Send Buffered • Closed
49. Channel Queue States Lock Free Linked List Node Empty Queue Send Buffered Send Queued Closed
50. val channel = Channel<Int>() Queue Empty Queue
51. val channel = Channel<Int>() channel.send(1)
52. class SendElement( val data: Any?, val cont: CancellableContinuation<Unit> ) : LockFreeLinkedListNode()
53. val channel = Channel<Int>() channel.send(1) Queue Send Element(1)
54. val channel = Channel<Int>() channel.send(1) channel.receive() Queue Empty Queue
55. val channel = Channel<Int>() channel.send(1) println(channel)
56. val channel = Channel<Int>() channel.send(1) println(channel) / / RendezvousChannel{SendQueued}
57. class AbstractSendChannel { fun toString() = {$queueDebugStateString}$bufferDebugString” } Query Channel State
58. class AbstractSendChannel { fun toString() = {$queueDebugStateString}$bufferDebugString” } Query Channel State
59. $queueDebugStateString get() { 
 when (head) { 
 is Closed < * > - > head.toString() 
 is Receive < * > - > "ReceiveQueued" 
 is Send - > "SendQueued" else - > "UNEXPECTED:$head" } } Query Channel State
60. $queueDebugStateString get() { 
 when (head) { 
 is Closed < * > - > head.toString() 
 is Receive < * > - > "ReceiveQueued" 
 is Send - > "SendQueued" else - > "UNEXPECTED:$head" } } Query Channel State
61. $queueDebugStateString get() { 
 when (head) { 
 is Closed < * > - > head.toString() 
 is Receive < * > - > "ReceiveQueued" 
 is Send - > "SendQueued" else - > "UNEXPECTED:$head" } } Query Channel State
62. $queueDebugStateString get() { 
 when (head) { 
 is Closed < * > - > head.toString() 
 is Receive < * > - > "ReceiveQueued" 
 is Send - > "SendQueued" else - > "UNEXPECTED:$head" } } Query Channel State
63. $queueDebugStateString get() { 
 when (head) { 
 is Closed < * > - > head.toString() 
 is Receive < * > - > "ReceiveQueued" 
 is Send - > "SendQueued" else - > "UNEXPECTED:$head" } } Query Channel State
64. val channel = Channel<Int>() channel.send(1) println(channel) / / RendezvousChannel{SendQueued} Query Channel State
65. runBlocking { 
 val channel = Channel<Int>(10) launch { channel.send(1) channel.send(2) channel.send(3) } }
66. runBlocking { 
 val channel = Channel<Int>(10) launch { channel.send(1) channel.send(2) channel.send(3) println(channel) } }
67. runBlocking { 
 val channel = Channel<Int>(10) launch { channel.send(1) channel.send(2) channel.send(3) println(channel) } } / / BufferedChannel{SendQueued}{3}
68. fun CoroutineScope.producer(): ReceiveChannel<Int> = 
 produce { for (i in 1 . . 5) { send(i) } }
69. fun CoroutineScope.producer(): ReceiveChannel<Int> = 
 produce { for (i in 1 . . 5) { send(i) } }
70. fun CoroutineScope.producer(): ReceiveChannel<Int> = 
 produce { for (i in 1 . . 5) { send(i) } close() }
71. runBlocking { 
 val channel: ReceiveChannel<Int> = producer() for (num in channel) { calculate(num) } }
72. runBlocking { 
 val channel: ReceiveChannel<Int> = producer() for (num in channel) { } }
73. interface ChannelIterator<out E> { suspend fun hasNextSuspend(): E fun next(): E } Channel Iterator
74. Coroutine A EmptyQueue Channel Queue Coroutine B
75. Coroutine A SendElement(1) Channel Queue Coroutine B 1
76. Coroutine A SendElement(1) Channel Queue Coroutine B 1 hasNext()
77. Coroutine A SendElement(1) Channel Queue Coroutine B 1 next()
78. Coroutine A SendElement(1) Channel Queue Coroutine B 1 next()
79. Coroutine A SendElement(1) Channel Queue Coroutine B 1 next() 2 3
80. Coroutine A SendElement(1) Channel Queue Coroutine B 1 2 3 X
81. runBlocking { 
 val channel: ReceiveChannel<Int> = producer() for (num in channel) { } }
82. Papers
83. Channels • Implementation • Use cases
84. marcoferrer/kroto-plus Code ! Issues Pull Requests Kroto-Plus+ - An RPC library and framework Bazel Build passing Gradle Build passing A Kotlin/JVM implementation of gRPC: A high performance, open source, general RPC framework that puts mobile and HTTP/2 first.
85. Server gRPC
86. Server gRPC service
87. Server(Go) gRPC service Client(Java) Client(Python) Client(Javascript) service service service
88. Server(Go) gRPC service Client(Java) Client(Python) Client(Javascript)
89. Server(Go) gRPC service Client(Java) Client(Python) Client(Javascript) call call call
90. Server(Go) gRPC service Client(Java) Client(Python) Client(Javascript) call call call HTTP 2
91. Channels with gRPC Client Server Scope (Dispatcher) Request Send Channel Receive Channel
92. Client Server Scope (Dispatcher) Request Send Channel Receive Channel Channels with gRPC
93. Client Server Scope (Dispatcher) Response Send Channel Receive Channel Channels with gRPC
94. Resources • Lock-free algorithms for Kotln Corotuines (Part 1) • Lock-free algorithms for Kotln Corotuines (Part 2) • gRPC with Kotlin Coroutines
95. Flows
96. Coroutine Coroutine Flow
97. Coroutine Coroutine Flow
98. val flow = flowOf(1,2,3)
99. val flow = flowOf(1,2,3) flow.collect { println(it) }
100. val flow = flow { emit(1) delay(2000) emit(1) }
101. flow .filter { } .map { } .combine(flow2) { }
102. flow .filter { } .map { } .combine(flow2) { } .flowOn(Dispatchers.IO)
103. flow.collect { }
104. flow.launchIn(scope)
105. fun Flow<T>.launchIn(scope: CoroutineScope): Job = scope.launch { collect() }
106. val value = flow.single()
107. Bridge to Flow
108. apollographql/apollo-android Code ! Issues Pull Requests Apollo Android Bazel Build passing Gradle Build passing Apollo Android is a GraphQL client that generates Java and Kotlin models from GraphQL queries.
109. val client = ApolloClient.builder() .serverUrl(“url") .build()
110. client.query(query).enqueue( object : ApolloCall.Callback() { override fun onResponse(response: Response) { } override fun onFailure(e: ApolloException) { } override fun onStatusEvent(event: ApolloCall.StatusEvent) { } })
111. client.query(query).enqueue( object : ApolloCall.Callback() { override fun onResponse(response: Response) { } override fun onFailure(e: ApolloException) { } override fun onStatusEvent(event: ApolloCall.StatusEvent) { } })
112. Callback Flow • Coroutine on Produce Scope • Provides a channel to send
113. callbackFlow { }
114. callbackFlow { enqueue( object : ApolloCall.Callback<T>() { override fun onResponse(response: Response<T>) { offer(response) } override fun onFailure(e: ApolloException) { close(e) } override fun onStatusEvent(event: ApolloCall.StatusEvent) { if (event = = ApolloCall.StatusEvent.COMPLETED) { close() } }
115. callbackFlow { enqueue( object : ApolloCall.Callback<T>() { override fun onResponse(response: Response<T>) { offer(response) } override fun onFailure(e: ApolloException) { close(e) } override fun onStatusEvent(event: ApolloCall.StatusEvent) { if (event = = ApolloCall.StatusEvent.COMPLETED) { close() } }
116. callbackFlow { enqueue( object : ApolloCall.Callback<T>() { override fun onResponse(response: Response<T>) { offer(response) } override fun onFailure(e: ApolloException) { close(e) } override fun onStatusEvent(event: ApolloCall.StatusEvent) { if (event = = ApolloCall.StatusEvent.COMPLETED) { close() } }
117. callbackFlow { enqueue( object : ApolloCall.Callback<T>() { override fun onResponse(response: Response<T>) { offer(response) } override fun onFailure(e: ApolloException) { close(e) } override fun onStatusEvent(event: ApolloCall.StatusEvent) { if (event = = ApolloCall.StatusEvent.COMPLETED) { close() } }
118. callbackFlow { 
 enqueue( . . . ) 
 awaitClose { cancel() } }
119. fun <T> ApolloCall<T>.toFlow() { callbackFlow { 
 enqueue( . . . ) 
 awaitClose { this@toFlow.cancel() } } }
120. val flow = client.query(query).toFlow()
121. Combine
122. 1 2 3 1s 1s
123. 1 2 3 1s 1s val numbersFlow = flowOf(1,2,3) .onEach { delay(1000) }
124. A B C 2s 2s
125. A B C 2s 2s val lettersFlow = flowOf("A", “B","C") .onEach { delay(2000) }
126. 1 2 3 A B C 1s 1s 2s 2s Combine
127. numbersFlow.combine(lettersFlow) { number, letter - > }
128. numbersFlow.combine(lettersFlow) { number, letter - > "$number$letter" }
129. 1 2 3 A B C 1s 1s 2s 2s 1A 2A 3C 3A 3B
130. numbersFlow.combine(lettersFlow) { number, letter - > "$number$letter" }.collect { println(it) }
131. numbersFlow.combine(lettersFlow) { number, letter - > "$number$letter" }.collect { print(it) } HelloWorld.kt 1A 2A 3A 3B 3C
132. 1 2 3 A B C 1s 1s 2s 2s How did combine work?
133. 1.4.x 1.3.x Zip, Combine Implementation Evolution Selectors New Version
134. Selectors
135. Send Send Channel A Channel B
136. Send Send Channel A Channel B
137. Send Send Channel A Channel B Receive
138. Send Channel A Channel B Send Receive
139. Channel B Send Receive Channel A Send Receive Read simultaneously from both channels?
140. fun CoroutineScope.hello() = produce { while (true) { delay(300) send("Hello") } } Send Hello
141. fun CoroutineScope.world() = produce { while (true) { delay(500) send("World!") } } Send World!
142. val receiveChannel = hello() 
 fun CoroutineScope.hello() = produce { while (true) { delay(300) send("Hello") } } Send Hello
143. val receiveChannel = hello() receiveChannel.receive() 
 fun CoroutineScope.hello() = produce { while (true) { delay(300) send("Hello") } } Send Receive
144. Channel B Send Receive Channel A Send Receive Read simultaneously from both channels?
145. suspend fun selectHelloWorld(channelA, channelB) { }
146. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { } } Selector
147. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { } } Return
148. interface ReceiveChannel { onReceive: SelectClause1 val onReceiveOrNull: SelectClause1 onReceiveOrClosed: SelectClause1 }
149. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { channelA.onReceive { value - > } } }
150. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { channelA.onReceive { value - > } channelB.onReceive { value - > } } }
151. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { channelA.onReceive { value - > println(value) } channelB.onReceive { value - > println(value) } } }
152. val channelA = hello() val channelB = world() selectHelloWorld(channelA, channelB)
153. fun CoroutineScope.hello() = produce { while (true) { delay(300) send("Hello") } } selectHelloWorld(channelA, channelB)
154. fun CoroutineScope.hello() = produce { while (true) { delay(300) send("Hello") } } selectHelloWorld(channelA, channelB)
155. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { channelA.onReceive { value - > println(value) } channelB.onReceive { value - > println(value) } } } / / Hello
156. val channelA = hello() val channelB = world() selectHelloWorld(channelA, channelB) selectHelloWorld(channelA, channelB)
157. fun CoroutineScope.world() = produce { while (true) { delay(500) send("World!") } } selectHelloWorld(channelA, channelB)
158. fun CoroutineScope.world() = produce { while (true) { delay(500) send("World!") } } selectHelloWorld(channelA, channelB)
159. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { channelA.onReceive { value - > println(value) } channelB.onReceive { value - > println(value) } } } / / World!
160. val channelA = hello() val channelB = world() Close
161. interface ReceiveChannel { onReceive: SelectClause1 val onReceiveOrNull: SelectClause1 onReceiveOrClosed: SelectClause1 }
162. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { channelA.onReceiveOrNull { value - > } channelB.onReceiveOrNull { value - > } } }
163. suspend fun selectHelloWorld(channelA, channelB) { select<Unit> { channelA.onReceiveOrNull { value - > } channelB.onReceiveOrNull { value - > } } } Null when channelA closed
164. Channel B Send Receive Channel A Send Receive Read simultaneously from both channels Selectors
165. 1 2 3 A B C 1s 1s 2s 2s Combine
166. 1 2 3 Send Channel A
167. 1 2 3 Send Channel A
168. A B C Send Channel B
169. A B C Send Channel B
170. Send Channel B Send Channel A Selector A 1
171. Send Channel B Send Channel A Selector A 1
172. Send Channel B Send Channel A Selector A 1 Transform
173. Send Channel B Send Channel A Selector A 1
174. 1 2 3 A B C 1A 2A
175. Send Channel B Send Channel A Selector A
176. 1 2 3 A B C 1A 2A
177. Send Channel B Send Channel A Selector A
178. Send Channel B Send Channel A Selector A 2
179. Send Channel B Send Channel A Selector A 2
180. Send Channel B Send Channel A Selector A 2
181. suspend fun combine( first: Flow<T1>, second: Flow<T2>, transform: suspend FlowCollector<R>.(a: T1, b: T2) - > Unit ) { }
182. suspend fun combine( first: Flow<T1>, second: Flow<T2>, transform: suspend FlowCollector<R>.(a: T1, b: T2) - > Unit ) { }
183. suspend fun combine( . . . ) { val firstChannel = createChannel(firstFlow) val secondChannel = createChannel(secondFlow) }
184. suspend fun combine( . . . ) { val firstChannel = createChannel(firstFlow) val secondChannel = createChannel(secondFlow) var firstValue: Any? = null var secondValue: Any? = null }
185. suspend fun combine( . . . ) { val firstChannel = createChannel(firstFlow) val secondChannel = createChannel(secondFlow) var firstValue: Any? = null var secondValue: Any? = null var firstIsClosed = false var secondIsClosed = false }
186. suspend fun combine( . . . ) { while (!firstIsClosed | | !secondIsClosed) { } }
187. suspend fun combine( . . . ) { while (!firstIsClosed | | !secondIsClosed) { select<Unit> { } } }
188. select<Unit> { channelA.onReceive { value - > firstValue = value if (secondValue ! = = null) { transform( . . . ) } } channelB.onReceive { value - > secondValue = value if (secondValue ! = = null) { transform( . . . ) } }
189. select<Unit> { channelA.onReceive { value - > firstValue = value if (secondValue ! = = null) { transform( . . . ) } } channelB.onReceive { value - > secondValue = value if (firstValue ! = = null) { transform( . . . ) } }
190. 1 2 3 A B C 1s 1s 2s 2s Combine
191. Shared Flow
192. val channel = ConflatedBroadcastChannel(10)
193. val channel = ConflatedBroadcastChannel(10) channel.send(1) channel.send(2) / / Conflate previously sent
194. val channel = ConflatedBroadcastChannel(10) channel.send(1) channel.send(2) / / Conflate previously sent channel.close()
195. Shared Flow • Mutable State Flow • Mutable Shared Flow
196. View View Model State
197. class MyViewModel(): ViewModel() { } Jetpack View Model
198. val ViewModel.viewModelScope: CoroutineScope get() { return setTagIfAbsent(JOB_KEY, CloseableCoroutineScope( 
 SupervisorJob() + Dispatchers.Main.immediate) 
 ) }
199. class MyViewModel(): ViewModel() { val states = MutableStateFlow(State()) } State Flow
200. class MyViewModel(): ViewModel() { val states = MutableStateFlow(State()) fun updateState() { flowOfData .map { mapToState(data) } .onEach { state - > states.value = state } .launchIn(viewModelScope) } }
201. class MyViewModel(): ViewModel() { val states = MutableStateFlow(State()) fun updateState() { flowOfData .map { mapToState(data) } .onEach { state - > states.value = state } .launchIn(viewModelScope) } }
202. class MyViewModel(): ViewModel() { val states = MutableStateFlow(State()) fun updateState() { flowOfData .map { mapToState(data) } .onEach { state - > states.value = state } .launchIn(viewModelScope) } }
203. class MyViewModel(): ViewModel() { val states = MutableStateFlow(State()) fun updateState() { flowOfData .map { mapToState(data) } .collect { state - > 
 states.value = state } / / logic after collect will run after it finishes } } Suspending
204. class MyViewModel(): ViewModel() { val states = MutableStateFlow(State()) fun updateState() { flowOfData .map { mapToState(data) } .onEach { state - > states.value = state } .launchIn(viewModelScope) } }
205. class MyViewModel(): ViewModel() { val states = MutableSharedFlow() fun updateState() { flowOfData .map { mapToState(data) } .onEach { state - > states.value = state } .launchIn(viewModelScope) } }
206. class MyViewModel(): ViewModel() { val states = MutableSharedFlow() fun updateState() { flowOfData .map { mapToState(data) } .onEach { state - > states.emit(data) } .launchIn(viewModelScope) } }
207. Mutable State
208. State
209. State Coroutine Coroutine Coroutine
210. State Coroutine Coroutine Coroutine
211. Mutable State • Mutex • Actor
212. var counter = 0 suspend fun CoroutineScope.updateState() { }
213. var counter = 0 suspend fun CoroutineScope.updateState() { val jobs = List(100) { launch { } } }
214. var counter = 0 suspend fun CoroutineScope.updateState() { val jobs = List(100) { launch { repeat(1000) { counter + + } } } }
215. var counter = 0 updateState()
216. var counter = 0 updateState() println(counter) / / 71906
217. var counter = 0 updateState() println(counter) / / 56467
218. Mutex
219. public interface Mutex { val isLocked: Boolean suspend fun lock() fun unlock() }
220. var counter = 0 suspend fun CoroutineScope.updateState() { val jobs = List(100) { launch { repeat(1000) { counter + + } } } }
221. var mutext = Mutex() var counter = 0 suspend fun CoroutineScope.updateState() { val jobs = List(100) { launch { repeat(1000) { counter + + } } } }
222. var mutext = Mutex() var counter = 0 suspend fun CoroutineScope.updateState() { 
 val jobs = List(100) { launch { repeat(1000) { mutext.lock() counter + + } } } }
223. var mutext = Mutex() var counter = 0 suspend fun CoroutineScope.updateState() { 
 val jobs = List(100) { launch { repeat(1000) { mutext.lock() try { counter + + } finally { mutext.unlock() } }
224. var mutext = Mutex() var counter = 0 suspend fun CoroutineScope.updateState() { List(100) { launch { repeat(1000) { mutext.lock() try { counter + + } finally { mutext.unlock() } }
225. fun <T> Mutex.withLock(owner, action: () - > T): T { lock(owner) try { return action() } finally { unlock(owner) } }
226. var mutext = Mutex() var counter = 0 suspend fun CoroutineScope.updateState() { List(100) { launch { repeat(1000) { mutext.withLock { counter + + } 
 } } }
227. Actor
228. Actor
229. Actor State
230. Mailbox State Actor
231. Actor Mailbox Coroutine State
232. State Actor Mailbox Coroutine Event
233. State Actor Mailbox Coroutine Event
234. State Actor Mailbox Coroutine Event
235. sealed class CounterEvents { }
236. sealed class CounterEvents { object IncCounter : CounterEvents() }
237. sealed class CounterEvents { object IncCounter : CounterEvents() class GetCounter( val response: CompletableDeferred<Int> ): CounterEvents() }
238. fun CoroutineScope.counterActor() = actor<CounterEvents> { }
239. fun CoroutineScope.counterActor() = actor<CounterEvents> { var counter = 0 }
240. fun CoroutineScope.counterActor() = actor<CounterEvents> { var counter = 0 for (event in channel) { } }
241. fun CoroutineScope.counterActor() = actor<CounterEvents> { var counter = 0 for (event in channel) { when (event) { } } }
242. fun CoroutineScope.counterActor() = actor<CounterEvents> { var counter = 0 for (event in channel) { when (event) { is IncCounter - > counter + + } } }
243. fun CoroutineScope.counterActor() = actor<CounterEvents> { var counter = 0 for (event in channel) { when (event) { is IncCounter - > counter + + is GetCounter - > event.response.complete(counter) } } }
244. val actor = counterActor()
245. val actor = counterActor() suspend fun CoroutineScope.updateState() { List(100) { launch { repeat(1000) { actor.send(IncCounter()) 
 } } }
246. val actor = counterActor() val response = CompletableDeferred<Int>()
247. val actor = counterActor() val response = CompletableDeferred<Int>() actor.send(GetCounter(response))
248. val actor = counterActor() val response = CompletableDeferred<Int>() actor.send(GetCounter(response)) println(response.await())
249. Mutable State • Mutex • Actor
250. Resources • Articles on testing flows, coroutine, context and more! 
 
 https: / / codingwithmohit.com/posts/ • Talk on corotutines! 
 
 https: / / codingwithmohit.com/talks/
251. Thank You! www.codingwithmohit.com @heyitsmohit