Android engineering for scale at SoundCloud

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Subtitle STRATEGY

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Subtitle ├── com │ └── soundcloud │ ├── android │ │ ├── stream │ │ │ ├── StreamAdapter.java │ │ │ ├── StreamFragment.java │ │ │ ├── StreamModule.java │ │ │ ├── StreamOperations.java │ │ │ ├── StreamStorage.java │ │ │ └── StreamItemPresenter.java

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if (flags.isEnabled(Feature.SECRET_PROJECT)) { return “Secret project”; } else { return “Nothing here”; }

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<> branch <> master <> origin/master

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master abstraction layer <> <>

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master abstraction layer <>

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master <>

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master feature-B .isEnabled() .isEnabled() feature-A .isEnabled() feature-C

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Subtitle public MainActivity() { SoundCloudApplication.getObjectGraph().inject(this); addLifeCycleComponent(playerController); addLifeCycleComponent(adPlayerController); presenter.attach(this); }

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@Inject public PlayerController( EventBus eventBus, TrackPagerAdapter adapter, PlayerPresenter presenter, PlayQueueManager playQueueManager) { [...] }

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BETA

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iOS Android

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API Mobile

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Subtitle { "id":612849, "kind":"user", "permalink":"bazan", "username":"David Bazan", "uri":"https://api.soundcloud.com/users/612849", "permalink_url":"http://soundcloud.com/bazan", "avatar_url":"https://i1.sndcdn.com/avatars-000030728315- oe5uld-large.jpg?e76cf77", "country":"United States", "first_name":"David", "last_name":"Bazan", "full_name":"David Bazan", "description":"Known for his work fronting the enigmatic rock band Pedro the Lion, David Bazan\u2019s emotionally charged narratives, eye for telling detail, and mournful voice have more in common with J.D. Salinger\u2019s \u201cNine Stories\u201d or Flannery O\u2019Connor\u2019s \u201cWise Blood\u201d than with the usual lyrical slant of popular music. Bazan is a gifted storyteller, weaving parables of spiritual conflict, suburban ennui, and personal surrender into magnetic, well-crafted songs.\r\n\r\nHis debut solo full-length album, Curse Your Branches (out now on Barsuk), is a masterwork by a modern American poet at the height of his powers. Paste Magazine called him one of the \u201c100 Best Living Songwriters\u201d. This record is the deepest and most explicit exploration of his struggles with faith and a meditation on all things passed between the generations.", "city":"Seattle", "discogs_name":null, "myspace_name":"davidbazan", "website":"http://www.davidbazan.com", "website_title":"", "online":false, "track_count":32, { "collection":[ "hip hop", "chill", "electronic", "deep house", "party", "love", "rap", "happy", "study", "techno", "indie rock", "dubstep", "r&b", "relax", "country", "pop", "edm", "reggae", "house", "workout", "soundtrack", "reggaeton", "piano", "dance", "remix", "alternative", "summer", "instrumental", "rock", "morning", "funk", "classical", "punk", "electro", "trap", "club", "acoustic", "motivation", "jazz",

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bazooka scale -r 934e08c -n 30 -e PROD

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Subtitle @Provides PlayerController providePlayerController(Flags flags) { if (flags.isEnabled(Feature.VISUAL_PLAYER)) { return new SlidingPlayerController(); } else { return new LegacyPlayerController(); } }

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... ... ...

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Reactive!

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public final class EventQueue { public static final Queue PLAYBACK_STATE; public static final Queue PLAYBACK_PROGRESS; public static final Queue PLAYABLE_CHANGED; [...] }

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Subtitle eventBus.queue(EventQueue.PLAYABLE_CHANGE) .filter(PlayableEvent.IS_TRACK_FILTER) .doOnNext(invalidateUICache) .observeOn(AndroidSchedulers.mainThread())

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Subtitle Observable.combineLatest( eventBus.queue(EventQueue.PLAY_QUEUE_TRACK), eventBus.queue(EventQueue.PLAYER_UI), combineStates) .doOnNext(setTrackHasBeenSeen)