Asynchronous image decoding

.editorconfig

@@ -0,0 +1,8 @@
+[*.swift]
+indent_style = space
+indent_size = 4
+tab_width = 4
+end_of_line = crlf
+insert_final_newline = false
+max_line_length = 120
+trim_trailing_whitespace = true

Nuke.xcodeproj/project.pbxproj

@@ -128,6 +128,7 @@
 		0CDB92801DAF9BB900002905 /* CHANGELOG.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = CHANGELOG.md; sourceTree = "<group>"; };
 		0CDB92821DAF9BC600002905 /* README.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 		0CDB92831DAF9BCB00002905 /* Package.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Package.swift; sourceTree = "<group>"; };
+		207CFF4E2F92C1F8007289D8 /* .editorconfig */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = .editorconfig; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFileSystemSynchronizedBuildFileExceptionSet section */
@@ -275,6 +276,7 @@
 		0C9174861BAE99EE004A7905 = {
 			isa = PBXGroup;
 			children = (
+				207CFF4E2F92C1F8007289D8 /* .editorconfig */,
 				0C096C7B1BAE9ADD007FE380 /* Sources */,
 				0C7C06551BCA87EC00089D7F /* Tests */,
 				0C9174911BAE99EE004A7905 /* Products */,

Sources/Nuke/Decoding/ImageDecoderRegistry.swift

@@ -9,7 +9,7 @@ public final class ImageDecoderRegistry: @unchecked Sendable {
     /// A shared registry.
     public static let shared = ImageDecoderRegistry()
 
-    private var matches = [(ImageDecodingContext) -> (any ImageDecoding)?]()
+    private var matches = [(ImageDecodingContext) -> (any BaseImageDecoding)?]()
     private let lock = NSLock()
 
     /// Initializes a custom registry.
@@ -18,7 +18,7 @@ public final class ImageDecoderRegistry: @unchecked Sendable {
     }
 
     /// Returns a decoder that matches the given context.
-    public func decoder(for context: ImageDecodingContext) -> (any ImageDecoding)? {
+    public func decoder(for context: ImageDecodingContext) -> (any BaseImageDecoding)? {
         for match in matches.reversed() {
             if let decoder = match(context) {
                 return decoder
@@ -34,7 +34,7 @@ public final class ImageDecoderRegistry: @unchecked Sendable {
     /// The decoder is created once and is used for the entire decoding session,
     /// including progressively decoded images. If the decoder doesn't support
     /// progressive decoding, return `nil` when `isCompleted` is `false`.
-    public func register(_ match: @escaping (ImageDecodingContext) -> (any ImageDecoding)?) {
+    public func register(_ match: @escaping (ImageDecodingContext) -> (any BaseImageDecoding)?) {
         lock.withLock { matches.append(match) }
     }
 

Sources/Nuke/Decoding/ImageDecoding.swift

@@ -4,13 +4,15 @@
 
 import Foundation
 
+public protocol BaseImageDecoding: Sendable {}
+
 /// An image decoder.
 ///
 /// A decoder is a one-shot object created for a single image decoding session.
 ///
 /// - note: If you need additional information in the decoder, you can pass
 /// anything that you might need from the ``ImageDecodingContext``.
-public protocol ImageDecoding: Sendable {
+public protocol ImageDecoding: BaseImageDecoding {
     /// Returns `true` if you want the decoding to be performed on the decoding
     /// queue (see ``ImagePipeline/Configuration-swift.struct/imageDecodingQueue``). If `false`, the decoding will be
     /// performed synchronously on the pipeline operation queue. By default, `true`.
@@ -36,6 +38,24 @@ extension ImageDecoding {
     public func decodePartiallyDownloadedData(_ data: Data) -> ImageContainer? { nil }
 }
 
+public protocol AsyncImageDecoding: BaseImageDecoding {
+    /// Produces an image from the given image data.
+    func decode(_ data: Data) async throws -> ImageContainer
+
+    /// Produces an image from the given partially downloaded image data.
+    /// This method might be called multiple times during a single decoding
+    /// session. When the image download is complete, ``decode(_:)`` method is called.
+    ///
+    /// - returns: nil by default.
+    func decodePartiallyDownloadedData(_ data: Data) async -> ImageContainer?
+}
+
+extension AsyncImageDecoding {
+    /// The default implementation which simply returns `nil` (no progressive
+    /// decoding available).
+    public func decodePartiallyDownloadedData(_ data: Data) async -> ImageContainer? { nil }
+}
+
 public enum ImageDecodingError: Error, CustomStringConvertible, Sendable {
     case unknown
 
@@ -62,3 +82,26 @@ extension ImageDecoding {
         return ImageResponse(container: container, request: context.request, urlResponse: context.urlResponse, cacheType: context.cacheType)
     }
 }
+
+extension AsyncImageDecoding {
+    func decode(_ context: ImageDecodingContext) async throws -> ImageResponse {
+        // autoreleasepool does not support async-await
+        let container: ImageContainer = try await {
+            if context.isCompleted {
+                return try await decode(context.data)
+            } else {
+                if let preview = await decodePartiallyDownloadedData(context.data) {
+                    return preview
+                }
+                throw ImageDecodingError.unknown
+            }
+        }()
+
+#if !os(macOS)
+        if container.userInfo[.isThumbnailKey] == nil && !container.isPreview {
+            ImageDecompression.setDecompressionNeeded(true, for: container.image)
+        }
+#endif
+        return ImageResponse(container: container, request: context.request, urlResponse: context.urlResponse, cacheType: context.cacheType)
+    }
+}

Sources/Nuke/Internal/Log.swift

@@ -24,6 +24,17 @@ func signpost<T>(_ name: StaticString, _ work: () throws -> T) rethrows -> T {
     return result
 }
 
+func signpost<T>(_ name: StaticString, _ work: () async throws -> T) async rethrows -> T {
+    guard ImagePipeline.Configuration.isSignpostLoggingEnabled else { return try await work() }
+
+    let log = log.value
+    let signpostId = OSSignpostID(log: log)
+    os_signpost(.begin, log: log, name: name, signpostID: signpostId)
+    let result = try await work()
+    os_signpost(.end, log: log, name: name, signpostID: signpostId)
+    return result
+}
+
 private let log = Mutex(value: OSLog(subsystem: "com.github.kean.Nuke.ImagePipeline", category: "Image Loading"))
 
 enum Formatter {

Sources/Nuke/Pipeline/ImagePipeline+Cache.swift

@@ -49,15 +49,15 @@ extension ImagePipeline.Cache {
     ///   - request: The request. Make sure to remove the processors if you want
     ///   to retrieve an original image (if it's stored).
     ///   - caches: `[.all]`, by default.
-    public func cachedImage(for request: ImageRequest, caches: Caches = [.all]) -> ImageContainer? {
+    public func cachedImage(for request: ImageRequest, caches: Caches = [.all]) async -> ImageContainer? {
         if caches.contains(.memory) {
             if let image = cachedImageFromMemoryCache(for: request) {
                 return image
             }
         }
         if caches.contains(.disk) {
             if let data = cachedData(for: request),
-               let image = decodeImageData(data, for: request) {
+               let image = await decodeImageData(data, for: request) {
                 return image
             }
         }
@@ -222,12 +222,20 @@ extension ImagePipeline.Cache {
 
     // MARK: Private
 
-    private func decodeImageData(_ data: Data, for request: ImageRequest) -> ImageContainer? {
+    private func decodeImageData(_ data: Data, for request: ImageRequest) async -> ImageContainer? {
         let context = ImageDecodingContext(request: request, data: data, cacheType: .disk)
         guard let decoder = pipeline.delegate.imageDecoder(for: context, pipeline: pipeline) else {
             return nil
         }
-        return (try? decoder.decode(context))?.container
+
+        switch decoder {
+            case let decoder as ImageDecoding:
+                return (try? decoder.decode(context))?.container
+            case let decoder as AsyncImageDecoding:
+                return (try? await decoder.decode(context))?.container
+            default:
+                fatalError("Invalid BaseImageDecoding Implementation")
+        }
     }
 
     private func encodeImage(_ image: ImageContainer, for request: ImageRequest) -> Data? {

Sources/Nuke/Pipeline/ImagePipeline+Configuration.swift

@@ -30,7 +30,7 @@ extension ImagePipeline {
 
         /// Default implementation uses shared ``ImageDecoderRegistry`` to create
         /// a decoder that matches the context.
-        public var makeImageDecoder: @Sendable (ImageDecodingContext) -> (any ImageDecoding)? = {
+        public var makeImageDecoder: @Sendable (ImageDecodingContext) -> (any BaseImageDecoding)? = {
             ImageDecoderRegistry.shared.decoder(for: $0)
         }
 

Sources/Nuke/Pipeline/ImagePipeline+Delegate.swift

@@ -13,7 +13,7 @@ extension ImagePipeline {
         // MARK: Misc
 
         /// Returns image decoder for the given context.
-        func imageDecoder(for context: ImageDecodingContext, pipeline: ImagePipeline) -> (any ImageDecoding)?
+        func imageDecoder(for context: ImageDecodingContext, pipeline: ImagePipeline) -> (any BaseImageDecoding)?
 
         /// Returns image encoder for the given context.
         func imageEncoder(for context: ImageEncodingContext, pipeline: ImagePipeline) -> any ImageEncoding
@@ -126,7 +126,7 @@ extension ImagePipeline.Delegate {
         pipeline.configuration.dataCache
     }
 
-    public func imageDecoder(for context: ImageDecodingContext, pipeline: ImagePipeline) -> (any ImageDecoding)? {
+    public func imageDecoder(for context: ImageDecodingContext, pipeline: ImagePipeline) -> (any BaseImageDecoding)? {
         pipeline.configuration.makeImageDecoder(context)
     }
 

Sources/Nuke/Pipeline/ImagePipeline+Error.swift

@@ -19,7 +19,7 @@ extension ImagePipeline {
         /// By default, the pipeline uses ``ImageDecoders/Default`` as a catch-all.
         case decoderNotRegistered(context: ImageDecodingContext)
         /// Decoder failed to produce a final image.
-        case decodingFailed(decoder: any ImageDecoding, context: ImageDecodingContext, error: Swift.Error)
+        case decodingFailed(decoder: any BaseImageDecoding, context: ImageDecodingContext, error: Swift.Error)
         /// Processor failed to produce a final image.
         case processingFailed(processor: any ImageProcessing, context: ImageProcessingContext, error: Swift.Error)
         /// Load image method was called with no image request or no URL.

Sources/Nuke/Tasks/AsyncPipelineTask.swift

@@ -39,20 +39,63 @@ extension AsyncPipelineTask: ImageTaskSubscribers {
 }
 
 extension AsyncPipelineTask {
-    /// Decodes the data on the dedicated queue and calls the completion
-    /// on the pipeline's internal queue.
-    func decode(_ context: ImageDecodingContext, decoder: any ImageDecoding, _ completion: @escaping @ImagePipelineActor (Result<ImageResponse, ImagePipeline.Error>) -> Void) {
-        @Sendable func decode() -> Result<ImageResponse, ImagePipeline.Error> {
-            signpost(context.isCompleted ? "DecodeImageData" : "DecodeProgressiveImageData") {
-                Result { try decoder.decode(context) }
-                    .mapError { .decodingFailed(decoder: decoder, context: context, error: $0) }
-            }
+    @Sendable nonisolated func decode(
+        _ context: ImageDecodingContext,
+        using decoder: any ImageDecoding
+    ) -> Result<ImageResponse, ImagePipeline.Error> {
+        signpost(context.isCompleted ? "DecodeImageData" : "DecodeProgressiveImageData") {
+            Result { try decoder.decode(context) }
+                .mapError { .decodingFailed(decoder: decoder, context: context, error: $0) }
         }
-        guard decoder.isAsynchronous else {
-            return completion(decode())
+    }
+
+    @Sendable nonisolated func decode(
+        _ context: ImageDecodingContext,
+        using decoder: any AsyncImageDecoding
+    ) async -> Result<ImageResponse, ImagePipeline.Error> {
+        await signpost(context.isCompleted ? "DecodeImageData" : "DecodeProgressiveImageData") {
+            do {
+                return .success(try await decoder.decode(context))
+            } catch {
+                let mappedError = ImagePipeline.Error.decodingFailed(
+                    decoder: decoder,
+                    context: context,
+                    error: error
+                )
+
+                return .failure(mappedError)
+            }
         }
-        operation = pipeline.configuration.imageDecodingQueue.add {
-            completion(await performInBackground(decode))
+    }
+
+    /// Decodes the data on the dedicated queue and calls the completion
+    /// on the pipeline's internal queue.
+    func decode(
+        _ context: ImageDecodingContext,
+        decoder: any BaseImageDecoding,
+        _ completion: @escaping @ImagePipelineActor (Result<ImageResponse, ImagePipeline.Error>) -> Void
+    ) {
+        switch decoder {
+            case let decoder as ImageDecoding where decoder.isAsynchronous:
+                return completion(decode(context, using: decoder))
+
+            case let decoder as ImageDecoding:
+                operation = pipeline.configuration.imageDecodingQueue.add {
+                    let imageContainer = await performInBackground {
+                        self.decode(context, using: decoder)
+                    }
+
+                    completion(imageContainer)
+                }
+
+            case let decoder as AsyncImageDecoding:
+                operation = pipeline.configuration.imageDecodingQueue.add {
+                    let imageContainer = await self.decode(context, using: decoder)
+                    completion(imageContainer)
+                }
+
+            default:
+                fatalError("Invalid BaseImageDecoding Implementation")
         }
     }
 }

Sources/Nuke/Tasks/TaskFetchOriginalImage.swift

@@ -6,7 +6,7 @@ import Foundation
 
 /// Receives data from ``TaskLoadImageData`` and decodes it as it arrives.
 final class TaskFetchOriginalImage: AsyncPipelineTask<ImageResponse>, @unchecked Sendable {
-    private var decoder: (any ImageDecoding)?
+    private var decoder: (any BaseImageDecoding)?
     private var lastPreviewTime: CFAbsoluteTime?
 
     override func start() {
@@ -76,7 +76,7 @@ final class TaskFetchOriginalImage: AsyncPipelineTask<ImageResponse>, @unchecked
     }
 
     // Lazily creates decoding for task
-    private func getDecoder(for context: ImageDecodingContext) -> (any ImageDecoding)? {
+    private func getDecoder(for context: ImageDecodingContext) -> (any BaseImageDecoding)? {
         // Return the existing processor in case it has already been created.
         if let decoder {
             return decoder