Add isAsynchronous option to ImageDecoding

b9software · Jun 3, 2021 · ca3df01 · ca3df01
1 parent 6374195
commit ca3df01
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Showing 7 changed files with 39 additions and 30 deletions.
diff --git a/Sources/Core/ImageDecoding.swift b/Sources/Core/ImageDecoding.swift
@@ -21,6 +21,11 @@ import WatchKit
 /// - note: If you need additional information in the decoder, you can pass
 /// anything that you might need from the `ImageDecodingContext`.
 public protocol ImageDecoding {
+    /// Return `true` if you want the decoding to be performed on the decoding
+    /// queue (see `imageDecodingQueue`). If `false`, the decoding will be
+    /// performed synchronously on the pipeline operation queue. By default, `true`.
+    var isAsynchronous: Bool { get }
+
     /// Produces an image from the given image data.
     func decode(_ data: Data) -> ImageContainer?
 
@@ -32,10 +37,15 @@ public protocol ImageDecoding {
     func decodePartiallyDownloadedData(_ data: Data) -> ImageContainer?
 }
 
-public extension ImageDecoding {
+extension ImageDecoding {
+    /// Returns `true` by default.
+    public var isAsynchronous: Bool {
+        true
+    }
+
     /// The default implementation which simply returns `nil` (no progressive
     /// decoding available).
-    func decodePartiallyDownloadedData(_ data: Data) -> ImageContainer? {
+    public func decodePartiallyDownloadedData(_ data: Data) -> ImageContainer? {
         nil
     }
 }
@@ -85,6 +95,10 @@ extension ImageDecoders {
 
         public init() { }
 
+        public var isAsynchronous: Bool {
+            false
+        }
+
         public init?(data: Data, context: ImageDecodingContext) {
             guard let container = _decode(data) else {
                 return nil
@@ -201,6 +215,10 @@ extension ImageDecoders {
     public struct Empty: ImageDecoding {
         public let isProgressive: Bool
 
+        public var isAsynchronous: Bool {
+            false
+        }
+
         /// - parameter isProgressive: If `false`, returns nil for every progressive
         /// scan. `false` by default.
         public init(isProgressive: Bool = false) {

diff --git a/Sources/Core/ImagePipelineConfiguration.swift b/Sources/Core/ImagePipelineConfiguration.swift
@@ -206,8 +206,6 @@ extension ImagePipeline {
             }
         }
 
-        static var isFastTrackDecodingEnabled = true
-
         private var isCustomImageCacheProvided = false
 
         var debugIsSyncImageEncoding = false
@@ -242,12 +240,3 @@ extension ImagePipeline {
         }
     }
 }
-
-// MARK: - Helpers
-
-extension ImagePipeline.Configuration {
-    /// Fast-track decoding isn't performed on the operation queue.
-    static func isFastTrackDecodingEnabled(for decoder: ImageDecoding) -> Bool {
-        isFastTrackDecodingEnabled && (decoder is ImageDecoders.Default || decoder is ImageDecoders.Empty)
-    }
-}
diff --git a/Sources/Internal/Tasks/TaskFetchDecodedImage.swift b/Sources/Internal/Tasks/TaskFetchDecodedImage.swift
@@ -50,7 +50,7 @@ final class TaskFetchDecodedImage: ImagePipelineTask<ImageResponse> {
                 decoder.decode(data, urlResponse: urlResponse, isCompleted: isCompleted, cacheType: nil)
             }
         }
-        if ImagePipeline.Configuration.isFastTrackDecodingEnabled(for: decoder) {
+        if !decoder.isAsynchronous {
             self.sendResponse(decode(), isCompleted: isCompleted)
         } else {
             operation = pipeline.configuration.imageDecodingQueue.add { [weak self] in

diff --git a/Sources/Internal/Tasks/TaskLoadImage.swift b/Sources/Internal/Tasks/TaskLoadImage.swift
@@ -63,7 +63,7 @@ final class TaskLoadImage: ImagePipelineTask<ImageResponse> {
                 decoder.decode(data, urlResponse: nil, isCompleted: true, cacheType: .disk)
             }
         }
-        if ImagePipeline.Configuration.isFastTrackDecodingEnabled(for: decoder) {
+        if !decoder.isAsynchronous {
             didDecodeCachedData(decode())
         } else {
             operation = pipeline.configuration.imageDecodingQueue.add { [weak self] in

diff --git a/Tests/ImagePipelineTests/ImagePipelineProgressiveDecodingTests.swift b/Tests/ImagePipelineTests/ImagePipelineProgressiveDecodingTests.swift
@@ -35,12 +35,6 @@ class ImagePipelineProgressiveDecodingTests: XCTestCase {
             $0.isStoringPreviewsInMemoryCache = true
             $0.imageProcessingQueue.maxConcurrentOperationCount = 1
         }
-
-        ImagePipeline.Configuration.isFastTrackDecodingEnabled = false
-    }
-
-    override func tearDown() {
-        ImagePipeline.Configuration.isFastTrackDecodingEnabled = true
     }
 
     // MARK: - Basics
@@ -288,6 +282,11 @@ class ImagePipelineProgressiveDecodingTests: XCTestCase {
     // MARK: Back Pressure
 
     func testBackpressureImageDecoding() {
+        // GIVEN
+        pipeline = pipeline.reconfigured {
+            $0.makeImageDecoder = { _ in MockImageDecoder(name: "a") }
+        }
+
         let queue = pipeline.configuration.imageDecodingQueue
 
         // When we receive progressive image data at a higher rate that we can

diff --git a/Tests/ImagePipelineTests/ImagePipelineTests.swift b/Tests/ImagePipelineTests/ImagePipelineTests.swift
@@ -17,12 +17,6 @@ class ImagePipelineTests: XCTestCase {
             $0.dataLoader = dataLoader
             $0.imageCache = nil
         }
-
-        ImagePipeline.Configuration.isFastTrackDecodingEnabled = false
-    }
-
-    override func tearDown() {
-        ImagePipeline.Configuration.isFastTrackDecodingEnabled = true
     }
 
     // MARK: - Completion
@@ -185,6 +179,10 @@ class ImagePipelineTests: XCTestCase {
 
     func testDecodingPriorityUpdated() {
         // Given
+        pipeline = pipeline.reconfigured {
+            $0.makeImageDecoder = { _ in MockImageDecoder(name: "test") }
+        }
+
         let queue = pipeline.configuration.imageDecodingQueue
         queue.isSuspended = true
 
@@ -246,7 +244,11 @@ class ImagePipelineTests: XCTestCase {
     }
 
     func testDecodingOperationCancelled() {
-        // Given
+        // GIVEN
+        pipeline = pipeline.reconfigured {
+            $0.makeImageDecoder = { _ in MockImageDecoder(name: "test") }
+        }
+
         let queue = pipeline.configuration.imageDecodingQueue
         queue.isSuspended = true
 

diff --git a/Tests/MemoryManagementTests/ImagePipelineMemoryTests.swift b/Tests/MemoryManagementTests/ImagePipelineMemoryTests.swift
@@ -73,8 +73,9 @@ class ImagePipelineMemoryTests: XCTestCase {
 
     func testDecodingOperationCancelled() {
         expectDeinit {
-            ImagePipeline.Configuration.isFastTrackDecodingEnabled = false
-            defer { ImagePipeline.Configuration.isFastTrackDecodingEnabled = true }
+            pipeline = pipeline.reconfigured {
+                $0.makeImageDecoder = { _ in MockImageDecoder(name: "test") }
+            }
 
             // Given
             let queue = pipeline.configuration.imageDecodingQueue