Okioに愛を込めて

OkioはSquareが開発しているjava.ioとjava.nioの取り回しを楽にしてくれるラッパーライブラリです。言わずと知れたOkHttpやMoshiのベースにも使用されているライブラリです。
Kotlinで書き直された2.0.0よりMPP（KMP）対応が行われ、3.0.0でファイルシステム周りの機能が追加されました。
KMP（android, iOS)プロジェクトで実際に使用した私がありがたいと感じた部分についてお話しします。

本セッションでは下記のことを取り扱います。

・標準ライブラリが強力なKotlinでなぜOkioを見直すのか
・KMP実装にIO周辺実装での諸課題
・KMP実装においてもOkioがもたらすメリット
・Okioを使用する際の注意するべき前提

Transcript

1. OkioʹѪΛࠐΊͯ RyuNen344 2024.06.22 Kotlin Fest
2. Today's TL;DR
3. Today's TL;DR ೰ΉͳΒ͍ͬͦOkio
4. • What we get/lost after Kotlinize/KMPnize? • About Okio • Source/Sink/Buffer/Segment • Big Love to ByteString • FileSystem and Path • How much does okio ommit our codes? • Okio? kotlinx-io? Outline
5. What we get after Kotlinize?
6. Null Safety What we get after Kotlinize? એݴΛݟΔ͚ͩͰnullΛ ͱΓ͏Δͷ͔͕Θ͔Δ
7. Immutability What we get after Kotlinize? ෆมΛ༏ઌͱͨ͠APIઃܭ
8. Unboxed Primitive Types What we get after Kotlinize? ΑΓݎ࿚ͳ੩తܕγεςϜ
9. Null Safety What we get after Kotlinize? Immutability Unboxed Primitive Types
10. Null Safety Unboxed Primitive Types Immutability What we get after Kotlinize? ࣦͬͨ΋ͷ͸ͳ͍ɾɾɾʁ
11. What we lost after Kotlinize? Q. Is Kotlin compatible with the Java programming language? A. Yes. Kotlin is 100% interoperable with https://kotlinlang.org/docs/faq.html
12. What we lost after Kotlinize? Q. ຊ౰ʹʁ A. ৚݅෇͖(ݸਓͷҙݟؚΉ)
13. • Primitive Array͸Immutableͱͯ͠એݴ͍ͯͯ͠΋஋ΛมߋͰ͖Δ What we lost after Kotlinize?
14. • ΑΓݎ࿚ͳܕγεςϜʹͳͬͨͨΊNumberͱPrimitiveͳArrayཁૉͷ ҉໧తܕม׵͕ࣦΘΕΔέʔε͕͋Δ • e.g.) Java: byte[]ͱKotlin: ByteArray What we lost after Kotlinize?
15. • ΑΓݎ࿚ͳܕγεςϜʹͳͬͨͨΊNumberͱPrimitiveͳArrayཁૉͷ ҉໧తܕม׵͕ࣦΘΕΔέʔε͕͋Δ What we lost after Kotlinize?
16. • ΑΓݎ࿚ͳܕγεςϜʹͳͬͨͨΊNumberͱPrimitiveͳArrayཁૉͷ ҉໧తܕม׵͕ࣦΘΕΔέʔε͕͋Δ What we lost after Kotlinize? intͱbyteͷ҉໧తͳม׵
17. • ΑΓݎ࿚ͳܕγεςϜʹͳͬͨͨΊNumberͱPrimitiveͳArrayཁૉͷ ҉໧తܕม׵͕ࣦΘΕΔέʔε͕͋Δ What we lost after Kotlinize? Int΋͘͠͸Byte΁ͷ໌ࣔతͳม׵
18. What we lost after KMPnize?
19. What we lost after KMPnize? java.* API ؙͬͱ࢖͑ͳ͍
20. Q. java.* API͕࢖͑ͳ͍ͱͲ͏ͳΔʁ What we lost after KMPnize? A. ࣮૷͕େมʹͳΔύλʔϯ͕͋Δ
21. Q1. java.util.Base64࢖͑ͳ͍͚ͲͲ͏͢Δʁ What we lost after KMPnize? A1. Plan1. expect/actualΛ࢖ͬͯࣗલ࣮૷ Plan2. kotlin.io.encoding.Base64(from Kotlin 1.8)Λ࢖͏
22. Q1. java.util.Base64࢖͑ͳ͍͚ͲͲ͏͢Δʁ What we lost after KMPnize? A1. Plan1. expect/actualΛ࢖ͬͯࣗલ࣮૷ Plan2. kotlin.io.encoding.Base64(from Kotlin 1.8)Λ࢖͏ stdlibʹػೳ͕֦ு͞ΕΕ͹ࣗલͰͳͯ͘Α͍ ʢkotlin.io.encoding.Base64͸platform͝ͱʹ࣮૷͕෼͔ΕΔ͔֬ ఆ͍ͯ͠ͳ͍ͷͰ஫ҙ͢Δඞཁ͸͋Δʣ
23. Q2. java.time API࢖͑ͳ͍͚ͲͲ͏͢Δʁ What we lost after KMPnize? A2. kotlinx-datetimeΛಋೖ͢Δ
24. Q2. java.time API࢖͑ͳ͍͚ͲͲ͏͢Δʁ What we lost after KMPnize? A2. kotlinx-datetimeΛಋೖ͢Δ ެࣜϥΠϒϥϦΛಋೖ͢Δ͜ͱͰղܾ͢ΔͷͰ͋Ε͹ͦΕͰΑ͍
25. Q3. java.io.{Input|Output}Stream͸ʁjava.io.File͸ʁ What we lost after KMPnize? A3.
26. Q3. java.io.{Input|Output}Stream͸ʁjava.io.File͸ʁ What we lost after KMPnize? A3. OkioΛೖΕ·͠ΐ͏ kotlinx-io͋Δ͚Ͳͦͷ࿩͸͋ͱͰ....
27. • Block(چSquare)͕ࣾ؅ཧ͢ΔOSS • ݩʑ͸OkHttpͷҰ෦ͱͯ͠java.io, java.nioͷऔΓճ͠ΛΑ͘͢Δͨ Ίʹ࡞ΒΕ͍ͯͨ • MoshiɺRetro fi tͰ΋core෦෼͸OkioΛ࢖࣮ͬͯ૷͞Ε͍ͯΔ About Okio
28. Source/Sink/Bu ff er/Segment Source/ Sink Buffer/ Segment
29. Source/Sink/Bu ff er/Segment Source/ Sink • {Input|Output}StreamʹରԠ͢ΔOkioಠࣗͷ interface • KtorͳͲͷϥΠϒϥϦ͸ࣗલͰಉ༷ͷ࣮૷Λ ߦͳ͍ͬͯͨΓ͢Δ • KMPʹ͸{Input|Output}Stream͕ͳ͍ͨΊɺ ͜ͷinterface͕KMPͱ࣮ͯ͠૷͞Ε͍ͯΔ͜ͱ ͕͋Γ͕͍ͨ
30. Source/Sink/Bu ff er/Segment Buffer/ Segment • ݩʑ͸java.nio.Bufferͷ֦ுΛ໨తͱͨ͠Ϋϥε • Buffer͸࣮σʔλͷίϯςφͰ͋ΔSegmentͷ॥؀Ϧ ετͰ࣮૷͞Ε͍ͯΔͨΊՄม௕ • σʔλͷҠಈΛSegmentͷ෇͚ସ͑ʹΑ࣮ͬͯݱ͢Δ • ҆શʹσʔλΛ௥ՃͰ͖Δ • ୯ʹByteArrayͷΠϯελϯεΛ৽͘͠࡞੒ͯ͠ί ϐʔ͢ΔΑΓলίετͰ஋ΛҠಈͰ͖Δ
31. Source/Sink/Bu ff er/Segment Buffer/ Segment • ݩʑ͸java.nio.Bufferͷ֦ுΛ໨తͱͨ͠Ϋϥε • Buffer͸࣮σʔλͷίϯςφͰ͋ΔSegmentͷ॥؀Ϧ ετͰ࣮૷͞Ε͍ͯΔͨΊՄม௕ • σʔλͷҠಈΛSegmentͷ෇͚ସ͑ʹΑ࣮ͬͯݱ͢Δ • ҆શʹσʔλΛ௥ՃͰ͖Δ • ୯ʹByteArrayͷΠϯελϯεΛ৽͘͠࡞੒ͯ͠ί ϐʔ͢ΔΑΓলίετͰ஋ΛҠಈͰ͖Δ sizeΛؾʹͨ͠ByteArray࣮૷͕ෆཁͰ͋Γ͕͍ͨ KMPͰ΋ಛੑͦͷ··ͳͷͰ͋Γ͕͍ͨ
32. • Τϯίʔυॲཧ͖ͭByteArray • HEX, UTF-8, Base64, MD5, SHA256, HMAC-SHA͕ϝιουҰͭͰॲ ཧͰ͖Δ • UTF-8ΛΤϯίʔυ͢Δࡍ͸ϝϞϦ্ʹΩϟογϡͯ͘͠ΕΔͷͰ࠶ Τϯίʔυ࣌ͷύϑΥʔϚϯε͕Α͍ Big Love to ByteString
33. • OkioશൠͰUTF-8Λલఏͱͨ͠IF͕૊·Ε͍ͯΔ • Java String͕಺෦తʹUTF-16ͰจࣈྻΛѻ͏ॾ໰୊Λߟྀ͠ͳͯ͘Α ͘ͳΔ • K/N͸Posix APIͰ͋Ε͜ΕΛૢ࡞͢ΔͷͰטΈ߹͍͕ྑ͍ • toString΋ࣗಈͰΤϯίʔυ͞ΕΔͷͰϓϦϯτσόοά͠΍͍͢ • e.g.) [size=0], [size=12, hex=AEADBFF] Big Love to ByteString
34. • OkioશൠͰUTF-8Λલఏͱͨ͠IF͕૊·Ε͍ͯΔ • Java String͕಺෦తʹUTF-16ͰจࣈྻΛѻ͏ॾ໰୊Λߟྀ͠ͳͯ͘Α ͘ͳΔ • K/N͸Posix APIͰ͋Ε͜ΕΛૢ࡞͢ΔͷͰטΈ߹͍͕ྑ͍ • toString΋ࣗಈͰΤϯίʔυ͞ΕΔͷͰϓϦϯτσόοά͠΍͍͢ • e.g.) [size=0], [size=12, hex=AEADBFF] Big Love to ByteString ByteStringલఏͰ࣮૷͢Δͱ ೰ΉՕॴ͕ݮͬͯ͋Γ͕͍ͨ
35. • ͦ΋ͦ΋JVM(android)͚ͩͰ΋ϑΝΠϧͷऔಘɺૢ࡞͸΍Γํ͕͍ͬͺ͍ ͋Δ • ClassLoader, TempDir, CacheDir, Asset, ExternalStorageɾɾɾɾ • ͡Ό͋ଞͷPlatform΋࣮૷͢Δͱͨ͠Βɾɾɾʁ • e.g.) Bundle, NSHomeDirectoryɾɾɾɾ • KotlinͷFileૢ࡞ܥͷAPI͸JVM onlyͷͨΊKMP͸ϑΝΠϧૢ࡞͕ۤखɾɾɾ FileSystem and Path
36. • java.nio. fi le.FileSystemͱjava.nio. fi le.PathʹͦΕͧΕରԠ͢Δokio.FileSystemͱ okio.PathͰߏ੒͞ΕΔ • JVM͸java.io or java.nioɺNative͸Posix APIʹΑΔ࣮૷ • androidͷAssetɺNode΍WASMͳͲ֤Platformઐ༻ͷ֦ு΋༻ҙͯ͋͠Δ • ֤PlatformͷAPIͷ্ʹinterfaceΛ༻ҙ͞Ε͍ͯΔͷͰ • ϢʔβʔಠࣗͷFileSystem࣮૷΋͓खܰͰ͋Γ͕͍ͨ • ςελϏϦςΟ͕޲্ͯ͋͠Γ͕͍ͨ FileSystem and Path
37. • ࣮ࡍʹͲΕ͙Β͍ίʔυ͕ݮΔͷ͔ʁ • ByteStringɿJWS(HS256) • FileSystem,PathɿcommonTestͷڞ௨Ϧιʔε How much does okio ommit our codes? Okioͷ༗ແͰൺֱͯ͠Έ·͠ΐ͏
38. Create JWS(HS256) with Okio eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMj M0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxN TE2MjM5MDIyfQ.kK9JnTXZwzNo3BYNXJT57PGLnQk- Xyu7IBhRWFmc4C0
39. Create JWS(HS256) with Okio eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMj M0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxN TE2MjM5MDIyfQ.kK9JnTXZwzNo3BYNXJT57PGLnQk- Xyu7IBhRWFmc4C0 ${header}.${payload}.${signature}
40. $header = base64url(json) $payload = base64url(json) $signature = base64url(HMAC-SHA256($ {header}.${payload})) $JWS = ${header}.${payload}. ${signature} Create JWS(HS256) with Okio
41. expect/actualͰ࡞Βͳ͖Ό͍͚ͳ͍΋ͷ͸ɾɾɾɾ 1. Base64ɿjava.util.Base64͕ແ͍ 2. HMAC-SHA256ɿjavax.crypto.Mac͕ແ͍ Create JWS(HS256) with Okio
42. Create JWS(HS256) with Okio
43. Create JWS(HS256) with Okio
44. Create JWS(HS256) with Okio
45. Create JWS(HS256) with Okio ७ਮʹ࣮૷͕ଟ͍ Platform͕૿͑Ε͹ͦͷ෼࣮૷΋૿͑Δ
46. Create JWS(HS256) with Okio
47. Create JWS(HS256) with Okio commonίʔυ͚ͩͰ׬݁ͯ͋͠Γ͕͍ͨ ϓϦϯτσόοά΋͠΍ͯ͋͘͢Γ͕͍ͨ
48. Shared CommonTest Resource with Okio • commonTest/resourcesʹ fi xture(json, proto...etc)Λ഑ஔ͢Δ૝ఆ • commonTest/resources഑ԼͷϑΝΠϧΛࢀর͢Δʹ͸Platform͝ͱ ʹ޻෉͕ඞཁ
49. Shared CommonTest Resource with Okio androidUnitTest iosTest current directory project root NSFileManager#currentDirectoryPath /Users/$name/Library/Developer/ CoreSimulator/Devices/$UUID/data resource directory ClassLoaderܦ༝ src/androidUnitTest/resource NSBundle.mainBundle.bundlePath build/bin/ios${arch}/debugTest
50. Shared CommonTest Resource with Okio androidUnitTest iosTest current directory project root NSFileManager#currentDirectoryPath /Users/$name/Library/Developer/ CoreSimulator/Devices/$UUID/data resource directory ClassLoaderܦ༝ src/androidUnitTest/resource NSBundle.mainBundle.bundlePath build/bin/ios${arch}/debugTest android΋iOS΋όϥόϥ😂
51. Shared CommonTest Resource with Okio • commonTest/resourcesͷ fi leΛࢀর͢Δexpect/actualΛ࡞੒͢Δ
52. Shared CommonTest Resource with Okio • commonTest/resourcesͷ fi leΛࢀর͢Δexpect/actualΛ࡞੒͢Δ ϑΝΠϧܾΊଧͪͰ͸औಘͰ͖Δ͕ ϑΝΠϧҰཡΛऔಘ͢Δ౳͕Ͱ͖ͳ͍
53. Shared CommonTest Resource with Okio • commonTest/resourcesͷPathΛฦ٫͢Δexpect/actualΛ࡞੒͢Δ
54. Shared CommonTest Resource with Okio • commonTest/resourcesͷPathΛฦ٫͢Δexpect/actualΛ࡞੒͢Δ
55. Shared CommonTest Resource with Okio • commonTest/resourcesͷPathΛฦ٫͢Δexpect/actualΛ࡞੒͢Δ OkioͷFileSystemͱPathΛ࢖͏͜ͱͰ ֦ுੑߴ͘resourceΛಡΈࠐΊΔΑ͏ʹͳͬͯ͋Γ͕͍ͨ
56. Okio? kotlinx-io? Q. ެࣜϥΠϒϥϦɺͳ͍ͷʁ A. ͋Γ·͢
57. Okio? kotlinx-io? Q. ެࣜϥΠϒϥϦɺͳ͍ͷʁ A. ͋Γ·͢
58. • Kotlin/kotlinx-io • ͠͹Β͘։ൃ͕ࢭ·͍͕ͬͯͨ1೥લ͙Β͍͔Β࠶։͞Εͨ experimentalͳϥΠϒϥϦʔ • جຊίϯηϓτ͸OkioͷSource, Sink, Buffer, Segment, ByteStringͱ ڞ௨ • ktor-io͸kotlinx-ioʹஔ͖׵͍͑ͯ͘༧ఆʢKTOR-6036ʣ Okio? kotlinx-io?
59. • kotlinx-ioͷ։ൃ͕࠶։͞ΕΔͷʹؾ͍ͮͨࣗ෼͕ڻ͍͍ͯΔπΠʔτ ͕ͪΐ͏Ͳ1೥લ͙Β͍Ͱͨ͠ Okio? kotlinx-io? https://twitter.com/RyuNen344/status/1668992754704105480
60. • Base64΍HASHؔ਺पΓ͸࣮૷͞Ε͍ͯͳ͍ • CipherStream౳ͷJVM Speci fi cͳAPI͸࣮૷͞Ε͍ͯͳ͍ • FileSystem͕sealed interfaceͰએݴ͞Ε͍ͯͯಠࣗͷFileSystemΛ࡞ ੒Ͱ͖ͳ͍ • FileSystemͷ࣮૷͕ΑΓPlatform Speci fi cͳAPIʹͳ͍ͬͯΔ • e.g.) iOSͷϑΝΠϧ؅ཧ͸NSFileManagerΛ࢖࣮ͬͯ૷ Okio? kotlinx-io?
61. Summary • KMP͸IO͕ۤख • OkioΛ࢖͏ͱจࣈΤϯίʔυɺόΠτ഑ྻૢ࡞Ͱ೰Ή৔໘͕ݮΔ • kotlinx-io΋։ൃ͞Ε͍ͯΔ͕ݱঢ়͸·ͩOkioΑΓػೳ͕ͳ͍
62. About Me • ଟ෼5೥͘Β͍androidΞϓϦ։ൃऀ • KMP޷͖ • Kodee͘Μͷ͵͍͙ΔΈ͕ཉ͍͠
63. OkioʹIOࠐΊͯ w w 2024.06.22 Kotlin Fest RyuNen344
64. Refs • https://square.github.io/okio/ • https://developer.squareup.com/blog/kotlin-multiplatform-shared- test-resources/ • https://x.com/ttuusskk/status/1722922182475694293/
65. EOF