projectreactor.io reactor3 intro

Transcript

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
30. Mono<T> for at most 1 element
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
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
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
61. flatMap(user -> tweetStream(user))
62. flatMap(user -> tweetStream(user))
63. flatMap(user -> tweetStream(user))
64. flatMap(user -> tweetStream(user))
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.