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"Ускорение сборки большого проекта на Objective-C + Swift" Иван Бондарь (Avito)

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После внедрения Swift в проект значительно увеличилось время сборки, что стало для нас существенным препятствием. В своём докладе я расскажу о том, как мы решили эту проблему, сократив время компиляции более чем в два раза.

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"Ускорение сборки большого проекта на Objective-C + Swift" Иван Бондарь (Avito)

  1. 1. Speed up build time of big project on Objective-C + Swift Ivan Bondar Lead iOS developer in Avito
  2. 2. Build time: 194.803s 75% of build time - Compile Swift files phase Swift: - *.swift files: 626 - LOC: 27264 Project structure Objective-C: - *.m files: 729 - LOC: 45947 - 217 imports in bridging-header
  3. 3. What to do • Tune build settings • Reduce .swift files count • Reduce extensions count • Optimize slow compiling functions • Fix warnings • Apply ccache compiler cache utility
  4. 4. Tune build settings Build Active Architecture Only Enable Objective-C Modules Debug data format - DWARF (no dsym file) Enable Whole module optimization
  5. 5. Tune build settings Debug data format - DWARF (no dsym file) Build time: 191.623s (194.803s before)
  6. 6. Tune build settings Whole module optimization Main target build time: 76.614 s Not suitable for debugging Can’t compile unit test target - segfault or weird errors with Swift-ObjC bridging
  7. 7. Reduce .swift files count Pre-build action - merge all Swift code to one FAT Swift file Not suitable for big projects: - can’t compile with segmentation fault 11 - eliminates «private» modifier - can’t use breakpoints in the original source
  8. 8. Reduce .swift files count Merge different classes/protocols in big .swift files Not suitable for VIPER in general Decided to apply only in certain cases, e.g. put Input and Output protocol declarations in one file
  9. 9. Reduce extensions count 0 10 20 30 40 100 1000 2000 3000 5000 10000 methods extensions * by Dmitry Bespalov https://tech.zalando.com/blog/speeding-up-xcode-builds/
  10. 10. Reduce extensions count class FilterViewController: UIViewController { } // MARK: UITableViewDelegate extension FilterViewController: UITableViewDelegate { } // MARK: UITableViewDataSource extension FilterViewController: UITableViewDataSource { } class FilterViewController: UIViewController, UITableViewDelegate, UITableViewDataSource { // MARK: UITableViewDelegate // MARK: UITableViewDataSource } Changes in code style applied Before: After: Extensions count reduced by 400 Build time: 94.3s (191.623s before)
  11. 11. Optimize slow compiling functions Profile compile time per function, filter by time > 1 ms. xcodebuild ARCHS=arm64 ONLY_ACTIVE_ARCH=NO -workspace App.xcworkspace -scheme App clean build OTHER_SWIFT_FLAGS="-Xfrontend -debug-time-function-bodies" | grep [1-9]. [0-9]ms | sort -nr > culprits.txt
  12. 12. Optimize slow compiling functions What to fix: • Functions with longest compile time • Functions with big number of occurrences 2871.3ms /Users/iyubondar/Projects/avito-ios/Models/Domain/Advertisement/Advertisement/Base/AdvertisementImage.swift:2:5 init(url100x75: String?, url140x105: String?, url240x180: String?, url432x324: String?, url640x480: String?, url1280x960: String?) 932.7ms /Users/iyubondar/Projects/avito-ios/Core/Extensions/UIKitExtensions/UICollectionView/UICollectionView+ChangeAnimations.swift:57:17 final class func changeSet<T : Hashable>(oldArray oldArray: [T], newArray: [T]) -> CollectionViewChangeSet 253.0ms /Users/iyubondar/Projects/avito-ios/Core/Extensions/UIKitExtensions/UICollectionView/UICollectionView+ChangeAnimations.swift:90:17 final class func changeSet<T>(oldArray oldArray: [T], newArray: [T], identityHashFunction: (T) -> Int, identityCheckFunction: (T, T) -> Bool, equalityCheckFunction: (T, T) -> Bool = default) -> CollectionViewChangeSet 136.0ms /Users/iyubondar/Projects/avito-ios/Presentation/Views/Advertisement/AdvertisementView/AdvertisementPresenter.swift:9:26 @objc public override func setModel(model: AnyObject!) 91.4ms/Users/iyubondar/Projects/avito-ios/Presentation/Views/Controls/PullToRefresh/ScrollViewRefresher.swift:251:18 private func handleRefreshingProgressChanged(progress: RefreshingProgress) 84.0ms/Users/iyubondar/Projects/avito-ios/VIPER/SelectCategoryParameters/Validation/SelectFromToValidator.swift:52:25 private final class func findValidRowIndex(valuesToSelect: [SelectCategoryParameterViewModel.Data], inCompareToValues compareValues: [SelectCategoryParameterViewModel.Data]?, selectedRowIndex: Int, iterationOrder: IterationOrder) -> Int 82.5ms/Users/iyubondar/Projects/avito-ios/Presentation/Views/Profile/ProfileViewPresenter.swift:30:10 @objc func notificationsSubtitle() -> String 81.8ms<invalid loc> init?(rawValue: String) currentDate: NSDate, calendar: NSCalendar, todayDateFormatter: NSDateFormatter, yesterdayDateFormatter: NSDateFormatter, weekdayDateFormatter: NSDateFormatter, dayDateFormatter: NSDateFormatter, yearDayDateFormatter: NSDateFormatter, fullDateFormatter: NSDateFormatter) -> String 8659 occurrences found.
  13. 13. Use lazy only when it's necessary 1204 occurrences found Compile time: 1.0 … 11.8 ms Optimize slow compiling functions private lazy var footerLabel: UILabel = { let footerLabel = UILabel() footerLabel.textColor = SpecColors.mainText footerLabel.font = SpecFonts.regular(14) footerLabel.autoresizingMask = .FlexibleWidth footerLabel.lineBreakMode = .ByWordWrapping footerLabel.numberOfLines = 0 footerLabel.textAlignment = .Center footerLabel.shadowColor = UIColor.whiteColor() footerLabel.shadowOffset = CGSize(width: 0, height: -1) return footerLabel }()
  14. 14. Avoid long expressions Compile time: 2871.3ms Optimize slow compiling functions self.thumbnailUrl = url240x180 ?? url140x105 ?? url100x75 ?? nil self.fullImageUrl = url640x480 ?? url432x324 ?? url1280x960 ?? url240x180 ?? url140x105 ?? url100x75 ?? nil self.thumbnailUrl = url240x180 ?? url140x105 ?? url100x75 self.fullImageUrl = url640x480 ?? url432x324 ?? url1280x960 ?? url240x180 ?? url140x105 ?? url100x75 Compile time: 916 ms
  15. 15. Avoid long expressions Optimize slow compiling functions var fullImageUrl: String? { if let url640x480 = url640x480 { return url640x480 } if let url432x324 = url432x324 { return url432x324 } … if let url100x75 = url100x75 { return url100x75 } return nil } Compile time: <1 ms
  16. 16. Use map() and flatMap() with care 1177 occurrences found Compile time: 2.5 … 21.8 ms Optimize slow compiling functions private lazy var tabControllers: [UIViewController] = { var controllers = [UIViewController?](count: Tab.tabsCount, repeatedValue: nil) controllers[Tab.Search.rawValue] = self.categoriesNavigationController() controllers[Tab.Favorites.rawValue] = self.favoritesNavigationController() controllers[Tab.Publish.rawValue] = self.publishNavigationController() controllers[Tab.Messenger.rawValue] = self.channelsRootViewController() controllers[Tab.Profile.rawValue] = self.profileNavigationController() return controllers.flatMap { $0 } }()
  17. 17. Use map() and flatMap() with care Optimize slow compiling functions Original example: http://irace.me/swift-profiling return [CustomType()] + array.map(CustomType.init) + [CustomType()] Compile time: 3158.2 ms and many occurrences
  18. 18. Give «type hints» to the compiler when necessary * example by IMPATHIC http://blog.impathic.com/post/99647568844/debugging-slow-swift-compile-times Optimize slow compiling functions func hangCompiler() { ["A": [ ["B": [ 1, 2, 3, 4, 5 ]], ["C": [ ]], ["D": [ ["A": [ 1 ]] ]] ]] } Build time: 54.249 s func hangCompiler() { ["A": [ ["B": [ 1, 2, 3, 4, 5 ]] as [String: [Int]], ["C": [ ]] as [String: [Int]], ["D": [ ["A": [ 1 ]] as [String: [Int]] ]] ]] } Build time: 1.293 s
  19. 19. Optimize slow compiling functions Build time: 92.5s (94.3s before) No great effect in our case Before: • 8659 functions > 1ms • max time 2871.3мс • median time 1.8ms After: • 2227 functions > 1ms • max time 124.3мс • median time 3.4ms
  20. 20. Fix warnings Swift Compiler Warnings: 64 total Warning type Count Build time after fix Parameters of ... have different optionality 3 92.5s User-defined 2 92.5s Cannot find protocol definition 3 90.481s Overriding instance method parameter with implicitly unwraped optional type 27 warnings 27 90.195s Deprecation 18 93.487s <Some code> will never been executed 1 93.654s Immutable value ... was never used 1 93.152s Pointer is missing nullability specifier 9 80.667s Build time: 80.667s (92.5s before)
  21. 21. Fix warnings But, with 1 warning <Some code> will never been executed, build time is 84.919s Fix all Swift Compiler Warnings to speed up build time!
  22. 22. Apply ccache compiler cache utility Build time: 68.403s (80.667s before) ccache limitations: - no support for Clang modules - no support for precompiled headers - no Swift support ccache applied to project
  23. 23. What was done Before: 194.803 s After: 68.403 s There is no silver bullet :( • Tune build settings - 3s • Reduce .swift files count - 0s • Reduce extensions count - 97s • Optimize slow compiling functions - 2s • Fix warnings - 12s • Apply ccache compiler cache utility -12s
  24. 24. Injection for Xcode plugin: + dynamically inserts new Swift / Objective-C code into a running app + support «tunable parameters» Source: https://github.com/johnno1962/injectionforxcode
  25. 25. Injection for Xcode plugin: Source: https://github.com/johnno1962/injectionforxcode Swift limitations. It’s not possible to: - Make changes to Structs. - Change functions or classes that are marked as final. - Change global functions or variables that are not constrained into a class.
  26. 26. Split app into frameworks with no cyclic dependencies between classes of different frameworks * Plans * idea and image: http://bits.citrusbyte.com/improving-swift-compile-time/
  27. 27. Further legacy code refactoring, remove Swift - Objective C dependencies. Plans
  28. 28. Links • http://bits.citrusbyte.com/improving-swift-compile-time/ • http://stackoverflow.com/questions/25537614/why-is-swift-compile-time-so-slow General: • http://blog.impathic.com/post/99647568844/debugging-slow-swift-compile-times • http://irace.me/swift-profiling Debug slow compile time: • https://tech.zalando.com/blog/speeding-up-xcode-builds/ • https://gist.github.com/lucholaf/e37f4d26e406250a156a Speed up builds: • https://developer.apple.com/videos/play/wwdc2015/409/ • http://useyourloaf.com/blog/swift-whole-module-optimization/ • http://useyourloaf.com/blog/modules-and-precompiled-headers/ • https://labs.spotify.com/2013/11/04/shaving-off-time-from-the-ios-edit-build-test-cycle/ • http://tomj.io/2015/08/29/speed-up-your-swift-test-builds-by-70-percent.html • https://pewpewthespells.com/blog/managing_xcode.html#dep-imp Build settings: • https://pspdfkit.com/blog/2015/ccache-for-fun-and-profit/ • https://ccache.samba.org/manual.html#_configuration ccache utility:
  29. 29. Questions?

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