diff options
| -rw-r--r-- | ios/MullvadVPN/Operations/AsyncOperation.swift | 45 |
1 files changed, 29 insertions, 16 deletions
diff --git a/ios/MullvadVPN/Operations/AsyncOperation.swift b/ios/MullvadVPN/Operations/AsyncOperation.swift index 98a5f8aa39..7edd3bbdd4 100644 --- a/ios/MullvadVPN/Operations/AsyncOperation.swift +++ b/ios/MullvadVPN/Operations/AsyncOperation.swift @@ -11,9 +11,16 @@ import Foundation /// A base implementation of an asynchronous operation class AsyncOperation: Operation, OperationProtocol { + /// A state transaction lock used to perform critical sections of code within `start`, `cancel` + /// and `finish` calls. + fileprivate let transactionLock = NSRecursiveLock() + /// A state lock used for manipulating the operation state flags in a thread safe fashion. fileprivate let stateLock = NSRecursiveLock() + /// The operation observers. + fileprivate var observers: [AnyOperationObserver<AsyncOperation>] = [] + /// Operation state flags. private var _isExecuting = false private var _isFinished = false @@ -36,8 +43,8 @@ class AsyncOperation: Operation, OperationProtocol { } final override func start() { - stateLock.withCriticalBlock { - if self._isCancelled { + transactionLock.withCriticalBlock { + if self.isCancelled { self.finish() } else { self.setExecuting(true) @@ -53,11 +60,17 @@ class AsyncOperation: Operation, OperationProtocol { /// Cancel operation /// Subclasses should override `operationDidCancel` instead final override func cancel() { - stateLock.withCriticalBlock { - if !self._isCancelled { + transactionLock.withCriticalBlock { + if self.isCancelled { + super.cancel() + } else { self.setCancelled(true) - if self._isExecuting { + super.cancel() + + // Only notify the operation about cancellation when it is already running, + // otherwise the call to `start` should automatically `finish()` the operation. + if self.isExecuting { self.operationDidCancel() } } @@ -71,17 +84,20 @@ class AsyncOperation: Operation, OperationProtocol { } final func finish() { - stateLock.withCriticalBlock { - if !self._isFinished { + transactionLock.withCriticalBlock { + guard !self.isFinished else { return } + + self.stateLock.withCriticalBlock { self.observers.forEach { $0.operationWillFinish(self) } } - if self._isExecuting { + if self.isExecuting { self.setExecuting(false) } - if !self._isFinished { - self.setFinished(true) + self.setFinished(true) + + self.stateLock.withCriticalBlock { self.observers.forEach { $0.operationDidFinish(self) } } } @@ -89,27 +105,24 @@ class AsyncOperation: Operation, OperationProtocol { private func setExecuting(_ value: Bool) { willChangeValue(for: \.isExecuting) - _isExecuting = value + stateLock.withCriticalBlock { _isExecuting = value } didChangeValue(for: \.isExecuting) } private func setFinished(_ value: Bool) { willChangeValue(for: \.isFinished) - _isFinished = value + stateLock.withCriticalBlock { _isFinished = value } didChangeValue(for: \.isFinished) } private func setCancelled(_ value: Bool) { willChangeValue(for: \.isCancelled) - _isCancelled = value + stateLock.withCriticalBlock { _isCancelled = value } didChangeValue(for: \.isCancelled) } // MARK: - Observation - /// The operation observers. - fileprivate var observers: [AnyOperationObserver<AsyncOperation>] = [] - /// Add type-erased operation observer fileprivate func addAnyObserver(_ observer: AnyOperationObserver<AsyncOperation>) { stateLock.withCriticalBlock { |