Synchronous Code

Tue, 19 May 2026 00:00:00 +0000

Synchronous Code

Most RawCull code uses async/await, actors, and task groups. Some Apple framework work is still fundamentally synchronous: ImageIO thumbnail decode, CoreImage RAW rendering, JPEG encoding, and direct binary MakerNote parsing. This page explains where that work lives and how the app keeps it from freezing the UI or starving Swift’s cooperative executor.

Source Map

Area	Files
Cancellation-aware blocking bridge	`RawParserKit/Sources/RawParserKit/CancellableImageIOWork.swift`
Thumbnail extraction	`SonyThumbnailExtractor.swift`, `NikonThumbnailExtractor.swift`
Embedded JPEG extraction	`JPGSonyARWExtractor.swift`, `JPGNikonNEFExtractor.swift`, `SonyRAWJPEGCreator.swift`
MakerNote parsing	`SonyMakerNoteParser.swift`, `NikonMakerNoteParser.swift`
App callers	`RequestThumbnail.swift`, `ScanAndCreateThumbnails.swift`, `ExtractAndSaveJPGs.swift`, `ScanAndExtractJPGs.swift`, `ZoomPreviewHandler.swift`
Sharpness scoring	`FocusMaskEngine+Scoring.swift`, `FocusMaskEngine+MaskGeneration.swift`

Why Blocking Work Matters

Swift’s cooperative thread pool expects async tasks to suspend instead of occupying threads for long periods. ImageIO and CoreImage calls often do not suspend; they block until decode/render work is done.

Blocking on RawCull

Synchronous Code

Synchronous Code

Source Map

Why Blocking Work Matters