Merge branch 'operation-cancellation-ios-105'

6 files changed, 40 insertions, 23 deletions

diff --git a/ios/Operations/AsyncBlockOperation.swift b/ios/Operations/AsyncBlockOperation.swift
index e23b138d53..43be9b8275 100644
--- a/ios/Operations/AsyncBlockOperation.swift
+++ b/ios/Operations/AsyncBlockOperation.swift
@@ -74,7 +74,7 @@ public class AsyncBlockOperation: AsyncOperation {
 
     public func addCancellationBlock(_ block: @escaping () -> Void) {
         dispatchQueue.async {
-            if self.isCancelled {
+            if self.isCancelled, self.isExecuting {
                 block()
             } else {
                 self.cancellationBlocks.append(block)
diff --git a/ios/Operations/AsyncOperation.swift b/ios/Operations/AsyncOperation.swift
index 2939f0708e..2ca049030c 100644
--- a/ios/Operations/AsyncOperation.swift
+++ b/ios/Operations/AsyncOperation.swift
@@ -307,8 +307,9 @@ open class AsyncOperation: Operation {
     private func _start() {
         operationLock.lock()
         if _isCancelled {
+            notifyCancellation()
             operationLock.unlock()
-            finish()
+            finish(error: OperationError.cancelled)
         } else {
             state = .executing
 
@@ -326,26 +327,21 @@ open class AsyncOperation: Operation {
     }
 
     override public final func cancel() {
-        var notifyDidCancel = false
-
         operationLock.lock()
         if !_isCancelled {
             _isCancelled = true
-            notifyDidCancel = true
-        }
-        operationLock.unlock()
-
-        super.cancel()
 
-        if notifyDidCancel {
-            dispatchQueue.async {
-                self.operationDidCancel()
-
-                for observer in self.observers {
-                    observer.operationDidCancel(self)
+            // Notify observers only when executing, otherwise `_start()` will take care of doing this as soon
+            // as operation is ready to execute.
+            if state == .executing {
+                dispatchQueue.async {
+                    self.notifyCancellation()
                 }
             }
         }
+        operationLock.unlock()
+
+        super.cancel()
     }
 
     public func finish() {
@@ -399,6 +395,14 @@ open class AsyncOperation: Operation {
         return true
     }
 
+    private func notifyCancellation() {
+        operationDidCancel()
+
+        for observer in _observers {
+            observer.operationDidCancel(self)
+        }
+    }
+
     // MARK: - Subclass overrides
 
     open func operationDidCancel() {
@@ -422,6 +426,17 @@ public protocol OperationBlockObserverSupport {}
 extension AsyncOperation: OperationBlockObserverSupport {}
 
 extension OperationBlockObserverSupport where Self: AsyncOperation {
+    /// Add observer responding to cancellation event.
+    public func onCancel(_ fn: @escaping (Self) -> Void) {
+        addBlockObserver(OperationBlockObserver(didCancel: fn))
+    }
+
+    /// Add observer responding to finish event.
+    public func onFinish(_ fn: @escaping (Self, Error?) -> Void) {
+        addBlockObserver(OperationBlockObserver(didFinish: fn))
+    }
+
+    /// Add block-based observer.
     public func addBlockObserver(_ observer: OperationBlockObserver<Self>) {
         addObserver(observer)
     }
diff --git a/ios/Operations/AsyncOperationQueue.swift b/ios/Operations/AsyncOperationQueue.swift
index 4579546084..d1269a8175 100644
--- a/ios/Operations/AsyncOperationQueue.swift
+++ b/ios/Operations/AsyncOperationQueue.swift
@@ -73,11 +73,9 @@ private final class ExclusivityManager {
 
             operationsByCategory[category] = operations
 
-            let blockObserver = OperationBlockObserver(didFinish: { [weak self] op, error in
+            operation.onFinish { [weak self] op, error in
                 self?.removeOperation(op, categories: categories)
-            })
-
-            operation.addObserver(blockObserver)
+            }
         }
     }
 
diff --git a/ios/Operations/NoFailedDependenciesCondition.swift b/ios/Operations/NoFailedDependenciesCondition.swift
index 2e96a12593..81523e511d 100644
--- a/ios/Operations/NoFailedDependenciesCondition.swift
+++ b/ios/Operations/NoFailedDependenciesCondition.swift
@@ -24,11 +24,15 @@ public final class NoFailedDependenciesCondition: OperationCondition {
 
     public func evaluate(for operation: Operation, completion: @escaping (Bool) -> Void) {
         let satisfy = operation.dependencies.allSatisfy { operation in
-            if let operation = operation as? AsyncOperation, operation.error != nil {
+            let operationError = (operation as? AsyncOperation)?.error
+            let isCancellationError = operationError?.isOperationCancellationError ?? false
+
+            if operationError != nil, !isCancellationError {
                 return false
             }
 
-            if operation.isCancelled, !self.ignoreCancellations {
+            // Treat OperationError.cancelled and isCancelled equally.
+            if operation.isCancelled || isCancellationError, !self.ignoreCancellations {
                 return false
             }
 
diff --git a/ios/Operations/ResultBlockOperation.swift b/ios/Operations/ResultBlockOperation.swift
index 5f21cd202e..5d848b438d 100644
--- a/ios/Operations/ResultBlockOperation.swift
+++ b/ios/Operations/ResultBlockOperation.swift
@@ -88,7 +88,7 @@ public final class ResultBlockOperation<Success>: ResultOperation<Success> {
 
     public func addCancellationBlock(_ block: @escaping () -> Void) {
         dispatchQueue.async {
-            if self.isCancelled {
+            if self.isCancelled, self.isExecuting {
                 block()
             } else {
                 self.cancellationBlocks.append(block)
diff --git a/ios/Operations/TransformOperation.swift b/ios/Operations/TransformOperation.swift
index 0b144707be..609e07896c 100644
--- a/ios/Operations/TransformOperation.swift
+++ b/ios/Operations/TransformOperation.swift
@@ -102,7 +102,7 @@ public final class TransformOperation<Input, Output>: ResultOperation<Output>, I
 
     public func addCancellationBlock(_ block: @escaping () -> Void) {
         dispatchQueue.async {
-            if self.isCancelled {
+            if self.isCancelled, self.isExecuting {
                 block()
             } else {
                 self.cancellationBlocks.append(block)