Set progress as cancelled if MultipartUpload is cancelled.

Observe `totalUnitCount` changes on master progress, for faster feedback and default progress.totalUnitCount to 0 (to correctly indicate indeterminate state.)
Synchronize access to setting and removing observers to prevent race conditions in `UploadOperation`.

Author: Ruben Nine

FilestackSDK/Internal/Operations/UploadOperation.swift

@@ -37,6 +37,7 @@ class UploadOperation: BaseOperation<JSONResponse> {
 
     private let masterProgress = Progress()
     private var masterProgressObservers: [NSKeyValueObservation] = []
+    private let lockQueue = DispatchQueue(label: "com.filestack.FilestackSDK.upload-operation-lock-queue")
 
     // MARK: - Lifecycle
 
@@ -76,17 +77,21 @@ extension UploadOperation {
 
 private extension UploadOperation {
     func setupProgressObservers() {
-        masterProgressObservers.append(masterProgress.observe(\.totalUnitCount, options: [.new]) { progress, _ in
-            self.progress.totalUnitCount = progress.totalUnitCount
-        })
+        lockQueue.sync {
+            guard !isCancelled else { return }
 
-        masterProgressObservers.append(masterProgress.observe(\.fractionCompleted, options: [.new]) { progress, _ in
-            self.progress.completedUnitCount = Int64(progress.fractionCompleted * Double(progress.totalUnitCount))
-        })
+            masterProgressObservers.append(masterProgress.observe(\.totalUnitCount) { progress, _ in
+                self.progress.totalUnitCount = progress.totalUnitCount
+            })
+
+            masterProgressObservers.append(masterProgress.observe(\.fractionCompleted) { progress, _ in
+                self.progress.completedUnitCount = Int64(progress.fractionCompleted * Double(progress.totalUnitCount))
+            })
+        }
     }
 
     func removeProgressObservers() {
-        masterProgressObservers.removeAll()
+        lockQueue.sync { masterProgressObservers.removeAll() }
     }
 
     func upload() {

FilestackSDK/Internal/Uploaders/MultipartUpload.swift

@@ -26,7 +26,7 @@ class MultipartUpload: Uploader, DeferredAdd {
 
         progress.kind = .file
         progress.fileOperationKind = .copying
-        progress.totalUnitCount = -1 // indeterminate
+        progress.totalUnitCount = 0 // indeterminate
 
         return progress
     }()
@@ -61,7 +61,13 @@ class MultipartUpload: Uploader, DeferredAdd {
 
     // MARK: - Uploadable Protocol Implementation
 
-    private(set) var state: UploadState = .notStarted
+    private(set) var state: UploadState = .notStarted {
+        didSet {
+            if state == .cancelled {
+                progress.cancel()
+            }
+        }
+    }
 
     @discardableResult func cancel() -> Bool {
         guard state != .cancelled else { return false }
@@ -122,10 +128,14 @@ private extension MultipartUpload {
 
         var results: [JSONResponse] = []
 
+        // Observe changes in `progress.totalUnitCount`.
+        progressObservers.append(masterProgress.observe(\.totalUnitCount) { progress, _ in
+            self.progress.totalUnitCount = progress.totalUnitCount
+        })
+
         // Observe changes in `progress.fractionCompleted`.
-        progressObservers.append(masterProgress.observe(\.fractionCompleted, options: [.new]) { progress, _ in
+        progressObservers.append(masterProgress.observe(\.fractionCompleted) { progress, _ in
             self.progress.completedUnitCount = Int64(progress.fractionCompleted * Double(progress.totalUnitCount))
-            self.progress.totalUnitCount = progress.totalUnitCount
 
             self.queue.async {
                 self.uploadProgress?(self.progress)

FilestackSDK/Public/Operations/BaseOperation.swift

@@ -23,7 +23,7 @@ open class BaseOperation<Success>: Operation {
 
     // MARK: - Private Properties
 
-    private var lockQueue = DispatchQueue(label: "com.filestack.FilestackSDK.operation-lock-queue")
+    private let lockQueue = DispatchQueue(label: "com.filestack.FilestackSDK.operation-lock-queue")
 
     private var _result: Result = .failure(.custom("Result not unavailable."))