Sequence x Iterable em Kotlin

Nessa apresentação trouxe a diferença do processamento de coleções em Kotlin entre Iterable e Sequence.
Além da comparação da performance entre as duas formas utilizando Jetpack Benchmark library.

Transcript

1. Sequence x Iterable em Kotlin Comparação de performance com Jetpack Benchmark
2. Hello! Angélica Oliveira Android Developer @ThoughtWorks Twitter: @AngOliveiraa Linkedin: @angelica-oliv 2
3. Listas 1.
4. Aplicativos quase sempre tem listas Timelines, listas de eventos, afazeres. Opções de filtragem, ordenação.. 4
5. Listas em Java x Listas em Kotlin 2.
6. Vamos imaginar uma lista de itens To-do Precisamos de um método que retorne apenas os itens marcados como feitos ordenados pelo nome 6
7. 7 List<TodoItem> getDoneItemOrderedTitle() { List<TodoItem> resultList = new ArrayList<>(); for(TodoItem todoItem: todoItemList) { if(todoItem.getDone()) { resultList.add(todoItem); } } Collections.sort(resultList, new Comparator<TodoItem>() { @Override public int compare(TodoItem todoItem1, TodoItem todoItem2) { return todoItem1.getName().compareTo(todoItem2.getName()); } }); return resultList; }
8. 8 fun getDoneItemOrderedTitle(): List<TodoItem> = todoItemList .filter { it.done } .sortedBy { it.name }
9. Diferença entre Sequence e Iterable 3.
10. 10 val list = listOf(0, 1, 2, 3) val sequence = sequenceOf(0, 1, 2, 3)
11. Iterable Diferentes formas de executar operações Sequence 11
12. Iterable ▪ Cada operação retorna uma lista intermediária Diferentes formas de executar operações Sequence ▪ Collection retornada apenas na operação final 12
13. Iterable ▪ Cada operação retorna uma lista intermediária ▪ Todas as operações são executadas na lista completa Diferentes formas de executar operações Sequence ▪ Collection retornada apenas na operação final ▪ Todas operações são executadas, um item por vez 13
14. 14 fun getFirstFromList() { LIST .map { println("map $it"); it * 5 } .filter { println("filter $it"); it % 2 == 0 } .take(1) .forEach { println("list $it") } }
15. 15 0 1 2
16. 16 0 1 2 map
17. 17 0 1 2 map
18. 18 0 1 2 map
19. 19 0 5 10 filter
20. 20 0 5 10 filter
21. 21 0 5 10 filter
22. 22 0 take 10
23. 23 fun getFirstFromList() { LIST .map { println("map $it"); it * 5 } .filter { println("filter $it"); it % 2 == 0 } .take(1) .forEach { println("list $it") } }
24. 24 fun getFirstFromSequence() { SEQUENCE .map { println("map $it"); it * 5 } .filter { println("filter $it"); it % 2 == 0 } .take(1) .forEach { println("sequence $it") } }
25. 25 0 1 2 map
26. 26 0 1 2 filter
27. 27 0 1 take 2
28. 28 fun getFirstFromSequence() { SEQUENCE .map { println("map $it"); it * 5 } .filter { println("filter $it"); it % 2 == 0 } .take(1) .forEach { println("sequence $it") } }
29. Vamos comparar a performance? 4.
30. Jetpack Benchmark ▪ Comparação de performance de código de aplicativos Android 30
31. Jetpack Benchmark ▪ Comparação de performance de código de aplicativos Android ▪ Execução de testes instrumentados 31
32. Jetpack Benchmark ▪ Comparação de performance de código de aplicativos Android ▪ Execução de testes instrumentados ▪ Resultados no output do Android Studio 32
33. Criar um módulo de Benchmark no projeto File -> New -> New Module 33
34. Implementar testes instrumentados 34 private val LARGE_LIST = (0..1000) private val LARGE_SEQUENCE = LARGE_LIST.asSequence()
35. Implementar testes instrumentados 35 @RunWith(AndroidJUnit4::class) class CompareIterableSequenceBenchmarkTest { @get:Rule val benchmarkRule = BenchmarkRule() @Test fun benchmarkListOperations() = benchmarkRule.measureRepeated { getFirstFromList(LARGE_LIST) } @Test fun benchmarkSequenceOperations() = benchmarkRule.measureRepeated { getFirstFromSequence(LARGE_SEQUENCE) } }
36. Resultados: 36 Lista com 1000 elementos
37. Resultados: 37 Lista com 3 elementos
38. Conclusões 5.
39. However, the lazy nature of sequences adds some overhead which may be significant when processing smaller collections or doing simpler computations. Hence, you should consider both Sequence and Iterable and decide which one is better for your case. 39
40. Conclusões ▪ Se tiver dúvida do que usar: 40
41. Conclusões ▪ Se tiver dúvida do que usar: □ Meça e compare 41
42. Conclusões ▪ Se tiver dúvida do que usar: □ Meça e compare ▪ Você pode usar a biblioteca Jetpack Benchmark pra isso! 42
43. Fontes ▪ Livro Effective Kotlin (Marcin Moskala) ▪ Documentação oficial Kotlin e Android Developers ▪ Template da apresentação SlidesCarnival 43
44. Quer saber mais? ▪ Medium ▪ Github sample project 44
45. Obrigada! Alguma pergunta? Você pode me achar em: ▪ Twitter: @AngOliveiraa ▪ Linkedin: @angelica-oliv 45
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47. Instructions for use EDIT IN POWERPOINT® Click on the button under the presentation preview that says "Download as PowerPoint template". You will get a .pptx file that you can edit in PowerPoint. Remember to download and install the fonts used in this presentation (you’ll find the links to the font files needed in the Presentation design slide) More info on how to use this template at www.slidescarnival.com/help-use-presentation-template This template is free to use under Creative Commons Attribution license. You can keep the Credits slide or mention SlidesCarnival and other resources used in a slide footer. EDIT IN GOOGLE SLIDES Click on the button under the presentation preview that says "Use as Google Slides Theme". You will get a copy of this document on your Google Drive and will be able to edit, add or delete slides. You have to be signed into your Google account. 47
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62. Let’s review some concepts Yellow Is the color of gold, butter and ripe lemons. In the spectrum of visible light, yellow is found between green and orange. Blue Is the colour of the clear sky and the deep sea. It is located between violet and green on the optical spectrum. Red Is the color of blood, and because of this it has historically been associated with sacrifice, danger and courage. Yellow Is the color of gold, butter and ripe lemons. In the spectrum of visible light, yellow is found between green and orange. Blue Is the colour of the clear sky and the deep sea. It is located between violet and green on the optical spectrum. Red Is the color of blood, and because of this it has historically been associated with sacrifice, danger and courage. 62
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