projectreactor.io reactor3 intro

Transcript

1. None

2. the Agenda

3. 101 Reactive Programming types & operators Reactor 3 and Spring

   Reactor debugging testing and other beasts backpressure and

4. 101 Reactive Programming types & operators Reactor 3 and Spring

   Reactor debugging testing and reactor-netty other beasts backpressure and reactor-kafka...

5. Reactive Programming 101 what does it bring to the table?

6. WHY? because blocking is evil

7. sync/blocking main thread processing resumes I/O BAD ! app does

   nothing

8. async & blocking main thread wait & join ! new

   threads, costly ! complex BAD

9. async & nonblocking “event loop” in non-blocking processing chunks no

   more threads than needed

10. how do you achieve that without losing your mind ?

11. Reactive Programming

12. Composing asynchronous & event-based sequences, using non-blocking operators “ ”

13. without sacrifice

14. without sacrifice Callbacks ? Futures ? easy to block hard

    to compose callback hell ! not readable

15. Pull? Push!

16. Pull? Push!

17. Pull? Push! (or actually a little bit of Both)

18. vs Iterable - Iterator Publisher - Subscriber

19. Data in Flux

20. Publisher Subscriber push events produces consumes feedback

21. interfaces from Reactive Streams spec Publisher Subscriber feedback consumes push

    events produces

22. Publisher Subscriber push events produces consumes feedback Subscriber<T> onNext(T) onComplete();

    onError(Throwable);

23. Publisher Subscriber produces consumes feedback 0..N elements + 0..1 (complete

    | error)

24. Publisher Subscriber push events produces consumes feedback backpressure

25. Publisher Subscriber push events produces consumes feedback can I have

    an API though?

26. Publisher Subscriber push events produces consumes feedback

27. Reactor 3 types and operators

28. Flux<T> for 0..N elements

29. None

30. Mono<T> for at most 1 element

31. None

32. Reactive Streams all the way

33. focus on Java 8

34. focus on Java 8 Duration, CompletableFuture, Streams

35. an Rx-inspired API with a vocabulary of operators similar to

    RxJava...

36. an Rx-inspired API ...but not exactly the same

37. Flux/Mono generator operator operator operator nothing happens until you subscribe

38. Flux/Mono generator Subscriber operator operator operator nothing happens until you

    subscribe

39. Flux/Mono generator Subscriber operator operator operator per Subscription state Sub

    Sub Sub

40. Flux/Mono generator Subscriber operator operator operator data flows Sub Sub

    Sub

41. examples

42. Flux.range Subscriber map filter buffer

43. None
44. None
45. None

46. Flux.range(5, 3) .map(i -> i + 3) .filter(i -> i

    % 2 == 0) .buffer(3)

47. Flux.range Subscriber map filter buffer

48. Flux.range Subscriber map filter buffer

49. Flux.range Subscriber map filter buffer

50. Flux.range Subscriber map filter buffer

51. Flux.range Subscriber map filter buffer

52. Flux.range Subscriber map filter buffer

53. Flux.range Subscriber map filter buffer

54. Flux.range(5, 3) .map(i -> i + 3) .filter(i -> i

    % 2 == 0) .buffer(3) 5, 6, 7 | 8, 9, 10 | 8, 10 | [8,10]|

55. Flux.from Subscriber map filter retry Publisher from HTTP reactive client

56. None

57. Flux.from Subscriber map filter retry Publisher from HTTP reactive client

58. Flux.from Subscriber map filter retry Publisher from HTTP reactive client

    resubscribe

59. go DEEPER! async sub-processes with flatMap

60. None

61. flatMap(user -> tweetStream(user))

62. flatMap(user -> tweetStream(user))

63. flatMap(user -> tweetStream(user))

64. flatMap(user -> tweetStream(user))

65. None

66. & much more...

67. threading contexts

68. Reactor is agnostic

69. however it facilitates switching

70. Schedulers

71. Schedulers elastic, parallel, single, timer...

72. publishOn switch rest of the flux on a thread

73. subscribeOn make the subscription and request happen on a particular

    thread

74. Flux/Mono generator operator subscribeO n operator publishOn operator operator Subscriber

    Sub Sub Sub Sub Sub Sub

75. Flux/Mono generator operator subscribe On operator publish On operator operator

    Subscriber Sub Sub Sub Sub Sub Sub

76. Flux/Mono generator operator subscribeO n operator publishOn operator operator Subscriber

    Sub Sub Sub Sub Sub Sub

77. Flux/Mono generator operator subscribeO n operator publishOn operator operator Subscriber

    Sub Sub Sub Sub Sub Sub

78. Flux/Mono generator operator subscribeO n operator publishOn operator operator Subscriber

    Sub Sub Sub Sub Sub Sub

79. Flux/Mono generator operator subscribeO n operator publishOn operator operator Subscriber

    Sub Sub Sub Sub Sub Sub

80. Testing & Debugging in an asynchronous world

81. Testing a Publisher StepVerifier

82. Testing a Publisher with Virtual Time support

83. Simulate a source TestPublisher

84. Debugging Issues stacktraces get hard to decipher

85. usually just show where Subscription happens

86. java.lang.IndexOutOfBoundsException: Source emitted more than one item at reactor.core.publisher.MonoSingle$SingleSubscriber.onNext(MonoSingle.java:120) at

    reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:314) ... ... at reactor.core.publisher.Mono.subscribeWith(Mono.java:2668) at reactor.core.publisher.Mono.subscribe(Mono.java:2629) at reactor.core.publisher.Mono.subscribe(Mono.java:2604) at reactor.core.publisher.Mono.subscribe(Mono.java:2582) at reactor.guide.GuideTests.debuggingActivated(GuideTests.java:727)

87. Find where the Flux was instantiated (assembly)

88. Checkpoint() or full assembly tracing

89. costly! Checkpoint() or full assembly tracing

90. Assembly trace from producer [reactor.core.publisher.MonoSingle] : reactor.core.publisher.Flux.single(Flux.java:5335) reactor.guide.GuideTests.scatterAndGather(GuideTests.java:689) reactor.guide.GuideTests.populateDebug(GuideTests.java:702)

91. BACKPRESSURE and other beasts

92. Publisher Subscriber subscribe

93. Publisher Subscriber push data as fast as possible

94. Publisher Subscriber subscribe with small request (eg. 1)

95. Publisher Subscriber 1 onNext

96. Publisher Subscriber request more (eg. 2)

97. Publisher Subscriber 2 onNext

98. Publisher Subscriber backpressure

99. other ways of dealing with backpressure eg. drop, buffer...

100. internal optimisations

101. macro FUSION avoids unnecessary request back-and-forth

102. micro FUSION share internal structures for less allocation

103. lock free operators

104. lock free operators and Work Stealing cpu 1 cpu 2

     cpu 3 cpu 4 cpu 5

105. Reactor and Spring

106. Reactor and Spring and do I need Spring to use

     Reactor ?

107. NO philosoraptor you don’t

108. Reactor 3 is a dependency of Spring 5 not the

     other way around

109. 5

110. Java 8 baseline

111. reactive focus

112. new WEB stack WebFlux

113. @RestController(“/user”) public class UserController { @GetMapping(“/{id}”) Mono<User> getUser(String id) {...}

     }

114. functional option for Routing

115. Spring Data reactive repositories

116. @GetMapping(“/{id}”) Mono<User> getUser(String id) { return reactiveRepo.findOne(id); }

117. Reactor and the Network reactor-netty

118. reactor-netty builds on Netty to provide reactive I/O

119. Client / Server

120. TCP or udp

121. Http and WebSockets

122. HttpServer.create(0) .newHandler((in, out) -> out .sendWebsocket((i, o) -> o.options(opt ->

     opt.flushOnEach()) .sendString(Flux.just("test") .delayElementsMillis(100) .repeat()) ) ) .block();

123. still a bit low level

124. still a bit low level

125. reactor-kafka topics as Flux<T>

126. reactive API over Kafka Producer / Consumer

127. send(Flux) into Kafka

128. Flux receive() from Kafka

129. (currently in MILESTONE 1)

130. Credits • Springfield Plant: copyright FOX • Raised Hand: CC0

     (via Pixabay) • Checklist: CC-By Crispy (via Flickr) • Robot Devil: copyright FOX • Volume Knob: CC0 (via Pixabay) • Camel Shape: CC0 (via Pixabay) • Dromedary Shape: CC-By-SA USPN,Whidou (via Wikimedia) • Dam: CC-By-SA Matthew Hatton (via geograph.org.uk) • Cogs: CC0 (via publicdomainpictures.net) • Thread Balls: CC0 (via Pixabay) • The Fortune Teller: Georges de la Tour (public domain) • Microphone: CC0 (via Pexels) • End Sands: CC0 (via Pixabay) • logos: Pivotal, Spring, Twitter and Github logo copyright their respective companies.