The document discusses coroutines in Kotlin and how they can be used to write asynchronous non-blocking code. It provides an example of converting imperative synchronous code into coroutine-based asynchronous code by suspending function calls and using continuations to chain asynchronous operations together. Coroutines allow breaking long-running operations into multiple steps that can complete without blocking the main thread.

1. TO B E CO N T I N U E D
K O T L I N C O U R O U T I N E S & P R O J E C T L O O M
A R T U R S KO W R O Ń S K I

4. A N Y B O D Y K O T L I N ?

5. B Y J E T B R A I N S
2 0 1 1

8. K O T L I N 1 . 3
1 0 . 2 0 1 8

9. K O T L I N 1 . 3
1 0 . 2 0 1 8
COROUTINES

10. W I L L T E A C H Y O U H O W C O R O U T I N E S W O R K S

11. W O N ’ T T E A C H Y O U H O W - T O - C O R O U T I N E

13. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

14. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

15. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

16. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

17. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

18. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

19. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

20. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

21. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

22. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

23. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

24. A LT E R N AT I V E S

25. COMPUTABLE FUTURES
fun combineAsync(name1: String, name2: String): CompletableFuture<Image>{
val future1 = CompletableFuture.supplyAsync(name1-> ...)
val future2 = CompletableFuture.supplyAsync(name2-> ...)
return future1.thenCombine(future2){i1,i2 -> ...}
}

26. REACTIVE EXTENSIONS
Observable<String> getTitle() {
return Observable.from(titleList);
}
Observable.just("book1", "book2")
.flatMap(s -> getTitle())
.subscribe(l -> result += l);
assertTrue(result.equals("titletitle"));

27. C O M P L E X I T Y

28. E X C E P T I O N H A N D L I N G I S H A R D

29. O V E R A L L I T ’ S H A R D

30. IMPERATIVE CODE
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

31. C O R O U T I N E S

32. 1 9 5 8

34. 1 9 6 3

35. NATIVE SUPPORT

36. NATIVE?

37. Roman Elizarov

38. IMPERATIVE CODE
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

39. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

40. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

41. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

42. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

43. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

44. BLOCKING
THREAD
Function 1
Function 2

45. SUSPEND
Suspension Point
THREAD
Function 1
Function 2

46. SUSPEND
THREAD
Coroutine 1
Function 2
getLocationsNearKnownPostcode getOpeningHours
Function 3

47. C O N T I N U AT I O N S

48. C O N T I N U AT I O N S

49. DIRECT STYLE CODE
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
ActionResult
Continuation
ACTION + RESULT & CONTINUATION

50. CONTINUATION PASSING STYLE
getLocationsNearKnownPostcode()
.success {location ->
val category = location.classification.category
}
Action
Result

51. CONTINUATION PASSING STYLE
getLocationsNearKnownPostcode()
.success {location ->
val category = location.classification.category
}
Action
Result
FANCY NAME FOR CALLBACKS

52. FROM KOTLIN FILE
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

53. JVM BYTECODE
public final static getLocationsNearKnownPostcode(Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
L0
LINENUMBER 33 L0
LDC "SW8 5YY, UK"
INVOKESTATIC TescoLocationAPIKt.getLocationsNearCoordinates (Ljava/lang/String;)Ljava/util/List;
ARETURN
L1
MAXSTACK = 1
MAXLOCALS = 1
// access flags 0x19
// signature (Ljava/lang/String;Lkotlin/coroutines/Continuation<Ljava/lang/Object;>;)Ljava/lang/Object;
// declaration: getOpeningHours(java.lang.String, kotlin.coroutines.Continuation<java.lang.Object>)
public final static getOpeningHours(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 37 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.getStoreDetails (Ljava/lang/String;)LLocationWrapper;
INVOKEVIRTUAL LocationWrapper.getOpeningHours ()[LLocationOpeningHours;
INVOKESTATIC kotlin/collections/ArraysKt.first ([Ljava/lang/Object;)Ljava/lang/Object;
CHECKCAST LocationOpeningHours
INVOKEVIRTUAL LocationOpeningHours.getStandardOpeningHours ()Ljava/util/HashMap;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2
// access flags 0x19
// signature (Ljava/lang/String;Lkotlin/coroutines/Continuation<Ljava/lang/Object;>;)Ljava/lang/Object;
// declaration: payInvoice(java.lang.String, kotlin.coroutines.Continuation<java.lang.Object>)
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2

54. TAKE A LOOK
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2

55. TAKE A LOOK
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

56. TAKE A LOOK
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

57. CONTINUATION INTERFACE
public interface Continuation<in T> {
public val context: CoroutineContext
public fun resumeWith(result: Result<T>)
}

58. TAKE A LOOK
public final static main()V
L0
LINENUMBER 13 L0
GETSTATIC kotlinx/coroutines/GlobalScope.INSTANCE : Lkotlinx/coroutines/GlobalScope;
CHECKCAST kotlinx/coroutines/CoroutineScope
ACONST_NULL
ACONST_NULL
NEW kotlinx/coroutines/guide/compose01/CoroutineCodeKt$main$1
DUP
ACONST_NULL
INVOKESPECIAL kotlinx/coroutines/guide/compose01/CoroutineCodeKt$main$1.<init> (Lkotlin/coroutines/Continuation;)V
CHECKCAST kotlin/jvm/functions/Function2
ICONST_3
ACONST_NULL
INVOKESTATIC kotlinx/coroutines/BuildersKt.launch$default (Lkotlinx/coroutines/CoroutineScope;Lkotlin/coroutines/CoroutineContext;Lkotlinx/coroutines/
CoroutineStart;Lkotlin/jvm/functions/Function2;ILjava/lang/Object;)Lkotlinx/coroutines/Job;
POP
L1

59. TAKE A LOOK
Coroutine
Stack
Operation 1
Operation 2
Operation 3
SUSPEND FUNCTION
Operation 1
Operation 2
Operation 3
Operation 4
Operation 5
SUSPEND FUNCTION
Operation 4
Operation 5
State
Operation 1
Operation 2
Operation 3

60. P R O J E C T L O O M

61. O P E R AT I N G S Y S T E M S 1 0 1

62. KERNEL SPACE THREADS
P R O C E S S E S
K E R N E L T H R E A D S
OS
PROCESS
PROCESS
THREAD
THREAD
THREAD
THREAD

63. KERNEL SPACE THREADS
C P U S C H E D U L E R
THREAD
Instruction 1
Instruction 2
Instruction 3
Instruction 4
THREAD
Continuation

64. OS
C P U S H E D U L E R
THREAD
THREAD
Instruction 1
Instruction 2
Instruction 3
Instruction 4

65. USER/KERNEL SPACE BORDER
CPU SHEDULER JVM
CONTEXT SWITCH

66. P R O J E C T M E T R O P O L I S

67. P R O J E C T VA L H A L L A

68. P R O J E C T PA N A M A

69. P R O J E C T A M B E R

70. P R O J E C T L O O M

71. USER/KERNEL SPACE BORDER
CPU SCHEDULER JVM
FORKJOINSCHEDULER
THREAD
THREAD
THREAD

72. USER/KERNEL SPACE BORDER
CPU SCHEDULER JVM
FORKJOINSCHEDULER
THREAD
Instruction 1
Instruction 2
Instruction 3
Instruction 4
Coroutines

73. CONTINUATION INTERFACE
public class Continuation implements Runnable {
public Continuation(ContinuationScope s, Runnable r)
public final void run()
public static void yield(ContinuationScope s)
public boolean isDone()
}

74. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

75. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

76. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

77. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

78. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

79. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

80. G E N E R AT O R S

81. ORIGINAL IDEA
SCHEDULER + CONTINUATION
Thread Fiber
Strand

82. NEW APPROACH
COPY AS MANY API AS POSSIBLE
Thread Fiber

83. G A I N S

84. T H R E A D S - ~ 1 M B

85. F I B E R - ~ 1 K B

86. N O M O R E T H R E A D P O O L S

87. L A C K O F C O M M O N A B S T R A C T I O N

88. D R A W B A C K S

89. C U R R E N T T H R E A D P R O B L E M

90. L A C K O F J N I S U P P O R T

91. C A N N O T S U S P E N D U N D E R L O C K

92. T H R E A D L O C A L

93. P R O C E S S O R / S C O P E L O C A L S

95. INITIAL INTERFACE
Fiber.schedule(Executor executor, Callable callable)

96. OBSOLETE
Fiber.schedule(Executor executor, Callable callable)

97. NEW INTERFACE
try (var scope = FiberScope.open()) {
var fiber1 = scope.schedule(task);
var fiber2 = scope.schedule(task);
}

98. S T R U C T U R E D C O N C U R R E N C Y

99. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

100. STRUCTURED CONCURRENCY
try (var scope = FiberScope.open(Option.PROPAGTE_CANCEL)) {
var fiber1 = scope.schedule(task);
var fiber2 = scope.schedule(task);
}

101. STRUCTURED CONCURRENCY
var deadline = Instant.now().plusSeconds(10);
try (var scope = FiberScope.open(deadline)) {
var fiber1 = scope.schedule(task);
var fiber2 = scope.schedule(task);
}

102. STRUCTURED CONCURRENCY
var deadline = Instant.now().plusSeconds(10);
try (var scope = FiberScope.open(deadline)) {
try (var scope2 = FiberScope.open()) {
scope2.schedule(() -> task());
}
}

103. STRUCTURED CONCURRENCY
var deadline = Instant.now().plusSeconds(10);
try (var scope = FiberScope.open(deadline)) {
try (var scope2 = FiberScope.open()) {
scope2.schedule(() -> task());
}
}

104. OBSOLETE (28.10.2019)
var deadline = Instant.now().plusSeconds(10);
try (var scope = FiberScope.open(deadline)) {
try (var scope2 = FiberScope.open()) {
scope2.schedule(() -> task());
}
}

105. D O N E W H E N I T ’ S D O N E

106. INSTALLATION STEPS
ONLY FOR JAVA => 11
hg clone https://github.com/openjdk/loom
cd loom
hg update -r fibers
sh configure
make images

107. OBSOLETE (23.08.2019)
hg clone https://github.com/openjdk/loom
cd loom
hg update -r fibers
sh configure
make images

108. P R O J E C T L O O M O N G I T

109. EARLY ACCESS BUILDS
2019/7/25
hg clone https://github.com/openjdk/loom
cd loom
hg update -r fibers
sh configure
make images

110. EARLY ACCESS BUILDS
2019/7/25

111. D AY B E F O R E M E E T U P

114. S O U R C E S
http://cr.openjdk.java.net/~rpressler/loom/Loom-Proposal.html
https://www.youtube.com/watch?v=YrrUCSi72E8
KOTLINCONF 2017 - DEEP DIVE INTO COROUTINES ON JVM BY ROMAN ELIZAROV
https://www.youtube.com/watch?v=vbGbXUjlRyQ
PROJECT LOOM: FIBERS AND CONTINUATIONS FOR JAVA BY ALAN BATEMAN
PROJECT LOOM: FIBERS AND CONTINUATIONS FOR THE JAVA VIRTUAL MACHINE

115. GQ U E S T I O N S ?