Async/Await functions in Ruby

## What’s takeaway of this session

- The basic use of Promise and Fiber
- The combination of Promise and Fiber performs like Async/Await syntax
- The naive Async/Await syntax sadly does NOT work efficiently in Graphql-ruby

Transcript

1. Async/Await functions in Ruby Sat, Dec. 14th, 2019 @平成Ruby会議01
2. @sat0yu - Software engineer at - Building microservices with gRPC and GraphQL - Three years of
3. What’s takeaway of this session 1. The basic use of Promise and Fiber 2. ★ The combination of Promise and Fiber performs like Async/Await syntax 3. ★★ The naive Async/Await syntax sadly does NOT work efficiently in ★: hard for @sat0yu to explain
4. GraphQL as an integrator *Note: just a part of the whole Quipper services
5. N+1 problems with GraphQL
7. ref. https://github.com/rmosolgo/graphql-ruby/blob/master/guides/schema/lazy_execution.md
8. How to use Graphql-batch - Build a loader so as inherit GraphQL::Batch::Loader - which need implementing perform(...)fetching data in bulk - Generate field values through the loader X.rb Y.rb ref. https://github.com/Shopify/graphql-batch
9. Nested loaders ref. https://github.com/Shopify/graphql-batch
10. “Promise” in Graphql-batch ref. https://github.com/Shopify/graphql-batch
11. - A representation of an eventual value - The value won’t be calculated until evaluating it (lazy-evaluation) - Chain-able with other promises through .then(...) What is “Promise”? fulfill reject pending fulfilled rejected ※ .load(...) returns a promise
12. Async/Await syntax with Promise and Genarator JavaScript
13. Async/Await in JavaScript - Declared in ES2017(ES8); Almost all browsers have compatibility - Convenient to write async processing with a synchronized-ish syntax JavaScript
14. Pause and Resume for promises - Declared in ES2017(ES8); Almost all browsers have compatibility - Convenient to write async processing with a synchronized-ish syntax sleeping... Pause Resume JavaScript
15. Promise + Generator ≈ Async/Await ≈ JavaScript
16. Generator pretends Pause and Resume JavaScript
17. Generator pretends Pause and Resume JavaScript How can we use Pause & Resume in Ruby?
18. Generator pretends Pause and Resume JavaScript Fiber (1.9~)
19. What is “Fiber”? ⏸
20. ⏩ What is “Fiber”?
21. ⏩ What is “Fiber”?
22. ⏩ What is “Fiber”?
23. ⏸ What is “Fiber”?
24. ⏩ What is “Fiber”?
25. ⏩ What is “Fiber”?
26. ⏩ What is “Fiber”?
27. ⏸ What is “Fiber”?
28. Async/Await syntax with Promise and Genarator Fiber
29. 2. Rewrite nested loaders with Fiber 1. Nested loaders implementation 3. Rewrite nested “resume”s
30. 1. Nested loaders implementation 2. Rewrite nested loaders with Fiber 3. Rewrite nested “resume”s
31. 1. Nested loaders implementation
32. 1. Nested loaders implementation
33. 1. Nested loaders implementation
34. 1. Nested loaders implementation
35. 1. Nested loaders implementation 2. Rewrite nested loaders with Fiber 3. Rewrite nested “resume”s
36. 2. Rewrite nested loaders with Fiber
37. ⏸ 2. Rewrite nested loaders with Fiber
38. ⏩ 2. Rewrite nested loaders with Fiber
39. ⏩ p1 2. Rewrite nested loaders with Fiber
40. ⏸ p1 next p1 2. Rewrite nested loaders with Fiber
41. ⏸ p1 next p1 2. Rewrite nested loaders with Fiber
42. ⏩ p1 next p1 2. Rewrite nested loaders with Fiber
43. ⏩ p1 next p1 p2 2. Rewrite nested loaders with Fiber
44. ⏸ p1 next p1 p2 next p2 2. Rewrite nested loaders with Fiber
45. ⏸ p1 next p1 p2 next p2 2. Rewrite nested loaders with Fiber
46. ⏩ p1 next p1 p2 next p2 2. Rewrite nested loaders with Fiber
47. p1 next p1 p2 next p2 X 2. Rewrite nested loaders with Fiber
48. p1 next p1 p2 next p2 X 2. Rewrite nested loaders with Fiber
49. Looks working 2. Rewrite nested loaders with Fiber
50. 1. Nested loaders implementation 2. Rewrite nested loaders with Fiber 3. Rewrite nested “resume”s
51. 3. Rewrite nested “resume”s
52. 3. Rewrite nested “resume”s
53. 3. Rewrite nested “resume”s
54. 3. Rewrite nested “resume”s
55. 3. Rewrite nested “resume”s
56. 3. Rewrite nested “resume”s
57. 3. Rewrite nested “resume”s
58. Looks working 3. Rewrite nested “resume”s
59. Let’s apply the naive Async/Await syntax to xx
60. Async/Await in
61. When fetching A and B fields
62. When fetching C and D fields N+1…
63. What’s wrong with the naive Async/Await? The naive Async/Await impl. returns a value, not a promise as a result Graphql-batch allows fields to return a promise in place of a value
64. Is it possible to fix it? - It makes me feel it’s do-able… but it does not work even if modifying it as returning a promise - The main difficulty comes from the difference in the promise life-cycle between Graphql-batch and the handcrafted Async/Await implementation
65. Summary - Explained the basic usage of Promise and Fiber - Confirmed the combination of Promise and Fiber works as Async/Await syntax - Observed that the naive impl. is not enough to work along with Graphql-batch - Code available: https://github.com/sat0yu/heisei-ruby-kaigi01 Thank you for your time and attention
66. appendix
67. Promise + Generator = Async/Await https://hackernoon.com/async-await-generators-promises-51f1a6ceede2 JavaScript
68. What is “Fiber”? https://www.slideshare.net/KoichiSasada/rubys-concurrency-management-now-and-future
69. Graphql-batch gives an example with concurrent-ruby https://github.com/Shopify/graphql-batch/blob/master/examples/http_loader.rb