How to reduce Android app launch time by scoping your dependencies using Koin DI

Aldo Kelvianto Wachyudi
LINE Indonesia Android Engineer
https://linedevday.linecorp.com/jp/2019/sessions/S2-3

Transcript

1. 2019 DevDay
   How To Reduce Android App
   Launch Time by Scoping Your
   Dependencies Using Koin DI
   > Aldo Kelvianto Wachyudi
   > LINE Indonesia Android Engineer
   

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2. Introduction
   > I've been working on LINE Today App project since 2018
   > LINE Today App version is now v4.1
   > LINE Today features: Read news, watch videos, listen to podcast, give
   comments
   > How do we maintain more features in the future?
   

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4. More
   Features
   More
   Objects
   More
   Modules
   

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5. Dev Day Schedule App
   List of Speakers
   Show News
   

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6. > SpeakerActivity
   > SpeakerModule // 7 objects
   List of Speaker
   News
   > NewsActivity
   > NewsModule // 6 objects
   Features, Activity, Module
   

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7. How To Inject These Modules?
   

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8. What's the Problem?
   > Production app has more than 2 modules and 15 objects
   > If we have 200 objects, it takes ~> 16.7 ms (skipped frame!)
   > Those objects linger in memories, used or not
   > Not ready to scale
   > Hard to maintain the code. Minor changes cause unexpected side-effect
   

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9. How To Improve This?
   > SpeakerActivity don't need NewsActivity objects, vice versa
   > Scope the objects
   "Scope is a fixed duration of time or
   method calls in which an object exists."
   

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10. Injection Result - Unscoped
    // 2 objects from context
    // 7 objects from speaker module
    // 6 objects from news module
    total 15 registered definitions
    load modules in 1.717 milliseconds
    

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11. Injection Result - Scoped
    // 73% faster!
    // Only binds 2 objects (Application and Context)
    total 15 registered definitions
    load modules in 0.448 milliseconds
    

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12. Scoping Benefit
    > Faster app launch time
    > The objects exist only when they're used
    > Ready to scale
    > More maintainable code
    

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13. How To Scope Module?
    Unscoped
    

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14. How To Scope Module?
    Scoped
    

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15. Summary
    > In Koin, Scope can ties to Activity, Fragment, ViewModel, or custom (define
    yourself)
    > It’s a concept, can be applied to any DI framework
    > In Dagger, you can use Scope annotation or Subcomponents
    > Code is available on https://github.com/aldoKelvianto/KoinScopeDemo
    

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