Extract Event/AsyncContext handling in a separate method

Sources/Nuke/ImageTask.swift

@@ -207,11 +207,26 @@ public final class ImageTask: Hashable, CustomStringConvertible, @unchecked Send
     // MARK: Events
 
     func process(_ event: Event) {
+        switch event {
+        case .progress(let progress):
+            currentProgress = progress
+        case .finished:
+            // TODO: do we need to check state?
+            _ = setState(.completed)
+        default:
+            break
+        }
+
         let context = sync { _context }
+        process(event, in: context)
+        onEvent?(event, self)
+        pipeline?.imageTask(self, didProcessEvent: event)
+    }
+
+    private func process(_ event: Event, in context: AsyncContext) {
         context.events?.1.yield(event)
         switch event {
         case .progress(let progress):
-            currentProgress = progress
             context.progress?.1.yield(progress)
         case .preview(let response):
             context.stream?.1.yield(response)
@@ -221,16 +236,12 @@ public final class ImageTask: Hashable, CustomStringConvertible, @unchecked Send
             context.stream?.1.finish(throwing: CancellationError())
             continuation?.resume(throwing: CancellationError())
         case .finished(let result):
-            _ = setState(.completed)
             let result = result.mapError { $0 as Error }
             context.events?.1.finish()
             context.progress?.1.finish()
             context.stream?.1.yield(with: result)
             continuation?.resume(with: result)
         }
-
-        onEvent?(event, self)
-        pipeline?.imageTask(self, didProcessEvent: event)
     }
 
     /// An event produced during the runetime of the task.

Sources/Nuke/Pipeline/ImagePipeline.swift

@@ -288,6 +288,7 @@ public final class ImagePipeline: @unchecked Sendable {
     private func makeStartedImageTask(with request: ImageRequest, isDataTask: Bool = false) -> ImageTask {
         let task = ImageTask(taskId: nextTaskId, request: request, isDataTask: isDataTask)
         task.pipeline = self
+        // TODO: we've added a dealy to startImageTask and that can be a problem
         task.task = Task {
             try await withUnsafeThrowingContinuation { continuation in
                 queue.async {
@@ -305,6 +306,10 @@ public final class ImagePipeline: @unchecked Sendable {
             return task.process(.finished(.failure(.pipelineInvalidated)))
         }
         // TODO: Check this and other .cancelled callbacks
+        // The problem is that if cancelled is called before that
+        // `startImageTask` is called, then the tasks[task] is empty
+        // in `ImageTask` callback and cancelation logic fails to run
+        // This can happen if the task is cancelled from `imageTaskCreated`
         guard task.state != .cancelled else {
             return task.process(.cancelled)
         }