Uncovering the magic behind Android Builds (DevFest Lima 2018)

Durante años el desarrollo de Android se ha venido apoyando en el uso de herramientas que nos ahorran la necesidad de ver el proceso de generación de APKs de forma cruda y pura. En esta charla hablaremos sobre este proceso desde el punto de vista de un Kotlin Developer y qué utilidad tiene conocer sobre ello.

https://devfestlima.com/schedule/2018-10-26?sessionId=324

Transcript

1. Uncovering the magic behind Android builds Armando Picón Android Engineer at Cornershop Inc. armando@cornershopapp.com @devpicon github.com/devpicon medium.com/devpicon
2. Android Engineer at Cornershop Inc. Lifelong learning developer
3. Some time ago…
7. Kotlin
8. Java interoperability
9. How?
10. Wait a minute! Let me give you some context first!
11. Android builds
12. Compilers Sources Libraries Resources Transforms Packaged Resources DX APK
13. Compilers Sources Libraries Resources Transforms Packaged Resources DX APK
14. javac Java source .java Transforms DX Dalvik bytecodes
15. javac Java source .java Transforms DX Dalvik bytecodes Java bytecode
16. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik bytecodes Java bytecode
17. *JVM = Java Virtual Machine
18. Java compatible bytecodes?
19. bytecodes?
20. https://en.wikipedia.org/wiki/Bytecode “Bytecode is a form of instruction set designed for efficient execution by a software interpreter.”
21. https://en.m.wikipedia.org/wiki/Java_bytecode “Java bytecode is the instruction set of the Java Virtual Machine (JVM)”
22. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes Java bytecode (.class)
23. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes Java bytecode (.class)
24. DX
25. Dalvik bytecodes?
26. https://source.android.com/devices/tech/dalvik
27. Java bytecodes != Dalvik bytecodes
28. • Stack-based machine • JVM bytecodes is composed by one or more .class file (each of this contains only one Java class) • JVM runs in almost every platform (except Android) • Each class is dynamically loaded depending of processing requirements • Register-based • Dalvik bytecode is only composed of one .dex file (containing all the classes of application) • DVM (before) and ART (now) runs only in Android • Every classes in the same DEX file are loaded by the same class loader instance Dalvik Bytecode Java Bytecode 
 & Java Compatible Bytecode from Kotlin
29. // access flags 0x11 public final main([Ljava/lang/String;)V @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0 L0 ALOAD 1 LDC "args" INVOKESTATIC kotlin/jvm/internal/ Intrinsics.checkParameterIsNotNull (Ljava/lang/Object;Ljava/ lang/String;)V L1 LINENUMBER 4 L1 ALOAD 0 GETSTATIC Kotlin$main$1.INSTANCE : LKotlin$main$1; CHECKCAST kotlin/jvm/functions/Function1 INVOKESPECIAL Kotlin.load2 (Lkotlin/jvm/functions/ Function1;)V L2 LINENUMBER 5 L2 RETURN L3 LOCALVARIABLE this LKotlin; L0 L3 0 LOCALVARIABLE args [Ljava/lang/String; L0 L3 1 MAXSTACK = 2 MAXLOCALS = 2 # virtual methods .method public final main([Ljava/lang/String;)V .registers 3 .param p1, "args" # [Ljava/lang/String; .annotation build Lorg/jetbrains/annotations/NotNull; .end annotation .end param const-string v0, "args" invoke-static {p1, v0}, Lkotlin/jvm/internal/Intrinsics;- >checkParameterIsNotNull(Ljava/lang/Object;Ljava/lang/ String;)V .line 4 sget-object v0, LKotlin$main$1;->INSTANCE:LKotlin$main$1; check-cast v0, Lkotlin/jvm/functions/Function1; invoke-direct {p0, v0}, LKotlin;->load2(Lkotlin/jvm/ functions/Function1;)V .line 5 return-void .end method Dalvik Bytecode Kotlin Bytecode
31. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes
32. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes
33. Incremental
34. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes Annotation Processing
35. Incremental
36. Incremental
37. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes Annotation Processing
38. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes Annotation Processing Desugaring Proguard rules
39. Desugaring • New java language features require new byte codes & new API • Older devices don’t support these • Developers don’t want to be stuck • Desugar replace new byte codes & language API with older ones
40. javac Java source .java Transforms DX kotlinc Kotlin source .kt Dalvik / Dex bytecodes Desugaring Proguard rules
41. javac Java source .java Transforms D8 kotlinc Kotlin source .kt Dalvik / Dex bytecodes Desugaring Proguard rules
42. D8 • New Dexer • Faster compilation • Smaller code • Better diagnostics
43. javac Java source .java Transforms D8 kotlinc Kotlin source .kt Dalvik / Dex bytecodes Desugaring Proguard rules
44. javac Java source .java Transforms D8 kotlinc Kotlin source .kt Dalvik / Dex bytecodes Desugaring Proguard rules
45. javac Java source .java Transforms R8 kotlinc Kotlin source .kt Dalvik / Dex bytecodes Desugaring Proguard rules
46. R8
47. R8 …Bye bye ProGuard??
48. R8 • New Shrinker & Optimizer • Faster compilation • Smaller code • Better diagnostics • ProGuard Compatible
49. What’s next?
50. • Best practices using compilers in Android Studio
 https://www.youtube.com/watch?v=gGOOkk2y_Ss&t=644s • What’s new in Android Runtime?
 https://www.youtube.com/watch?v=Yi9-BqUxsno&t=446s
51. Uncovering the magic behind Android builds Armando Picón Android Engineer at Cornershop Inc. armando@cornershopapp.com @devpicon github.com/devpicon medium.com/devpicon
52. Tweet with mention to @CornershopChile using hashtags 
 #DevFestLima18 And answer the following question:
53. What is Rubber duck debugging? @CornershopChile #DevFestLima18