[Maintenance] Add SerialExecutor for synchronously calling asynchronous jobs in order

Author: bo2themax

Sources/Utils/SerialExecutor.swift

@@ -0,0 +1,30 @@
+//
+//  SerialExecutor.swift
+//  AsyncBluetooth
+//
+//  Created by luca on 20.08.2025.
+//
+
+/// An executor that guarantees the async job order
+final class SerialExecutor: Sendable {
+    private let continuation: AsyncStream<() async -> Void>.Continuation
+
+    init() {
+        var c: AsyncStream<() async -> Void>.Continuation!
+        let stream = AsyncStream<() async -> Void> { cont in
+            c = cont
+        }
+        continuation = c
+
+        // Single task consuming jobs in FIFO order
+        Task {
+            for await job in stream {
+                await job()
+            }
+        }
+    }
+
+    func enqueue(_ job: @escaping () async -> Void) {
+        continuation.yield(job)   // sync, ordered
+    }
+}

Sources/Utils/ThreadSafeArray.swift

@@ -4,7 +4,7 @@ import Foundation
 
 actor ThreadSafeArray<Element> {
 
-    private var array: [Element]
+    private(set) var array: [Element]
 
     init(array: [Element] = []) {
         self.array = array

Tests/ThreadSafeArrayTest.swift

@@ -0,0 +1,23 @@
+//
+//  ThreadSafeArrayTest.swift
+//  AsyncBluetooth
+//
+//  Created by luca on 20.08.2025.
+//
+
+import Testing
+@testable import AsyncBluetooth
+
+@Test
+func orderTest() async throws {
+    let array: ThreadSafeArray<Int> = []
+    let executor = SerialExecutor()
+    for i in 1...1000 {
+        executor.enqueue {
+            await array.append(i)
+        }
+    }
+
+    try await Task.sleep(nanoseconds: UInt64(1e6))
+    try await #require(array.array == Array(1...1000))
+}