1 files changed, 98 insertions, 0 deletions
diff --git a/ios/Operations/AsyncOperationQueue.swift b/ios/Operations/AsyncOperationQueue.swift
new file mode 100644
index 0000000000..1c62038671
--- /dev/null
+++ b/ios/Operations/AsyncOperationQueue.swift
@@ -0,0 +1,98 @@
+//
+//  AsyncOperationQueue.swift
+//  MullvadVPN
+//
+//  Created by pronebird on 30/05/2022.
+//  Copyright © 2022 Mullvad VPN AB. All rights reserved.
+//
+
+import Foundation
+
+public class AsyncOperationQueue: OperationQueue {
+    override public func addOperation(_ operation: Operation) {
+        if let operation = operation as? AsyncOperation {
+            let categories = operation.conditions
+                .filter { condition in
+                    return condition.isMutuallyExclusive
+                }
+                .map { condition in
+                    return condition.name
+                }
+
+            if !categories.isEmpty {
+                ExclusivityManager.shared.addOperation(operation, categories: Set(categories))
+            }
+
+            super.addOperation(operation)
+
+            operation.didEnqueue()
+        } else {
+            super.addOperation(operation)
+        }
+    }
+
+    override public func addOperations(_ operations: [Operation], waitUntilFinished wait: Bool) {
+        for operation in operations {
+            addOperation(operation)
+        }
+
+        if wait {
+            for operation in operations {
+                operation.waitUntilFinished()
+            }
+        }
+    }
+}
+
+private final class ExclusivityManager {
+    static let shared = ExclusivityManager()
+
+    private var operationsByCategory = [String: [Operation]]()
+    private let nslock = NSLock()
+
+    private init() {}
+
+    func addOperation(_ operation: AsyncOperation, categories: Set<String>) {
+        nslock.lock()
+        defer { nslock.unlock() }
+
+        for category in categories {
+            var operations = operationsByCategory[category] ?? []
+
+            if let lastOperation = operations.last {
+                operation.addDependency(lastOperation)
+            }
+
+            operations.append(operation)
+
+            operationsByCategory[category] = operations
+
+            let blockObserver = OperationBlockObserver(didFinish: { [weak self] op, error in
+                self?.removeOperation(op, categories: categories)
+            })
+
+            operation.addObserver(blockObserver)
+        }
+    }
+
+    private func removeOperation(_ operation: Operation, categories: Set<String>) {
+        nslock.lock()
+        defer { nslock.unlock() }
+
+        for category in categories {
+            guard var operations = operationsByCategory[category] else {
+                continue
+            }
+
+            if let index = operations.firstIndex(of: operation) {
+                operations.remove(at: index)
+            }
+
+            if operations.isEmpty {
+                operationsByCategory.removeValue(forKey: category)
+            } else {
+                operationsByCategory[category] = operations
+            }
+        }
+    }
+}