isenwald2022's questions

我正在阅读这个博客，因为我有一个类似的用例：https://kelvas09.github.io/blog/posts/closure-delegate-to-async/

我注意到以下片段：

actor BluetoothLEScanWrapper {

enum BluetoothLEScanError: Error {
    case bluetoothNotAvailable
}

private let bluetoothLEDelegate: BluetoothLEDelegate = BluetoothLEDelegate()
private var activeTask: Task<[BluetoothLEDevice], Error>?

func scan(for seconds: Double = 3.0) async throws -> [BluetoothLEDevice] {

    if let existingTask = activeTask {
        return try await existingTask.value
    }

    let task = Task<[BluetoothLEDevice], Error> {
        guard bluetoothLEDelegate.bluetoothIsOn else {
            activeTask = nil
            throw BluetoothLEScanError.bluetoothNotAvailable
        }

        self.bluetoothLEDelegate.central.scanForPeripherals(withServices: nil)

        try await Task.sleep(nanoseconds: (UInt64(seconds) * 1_000_000_000))

        let devices = bluetoothLEDelegate.foundPeripheral.compactMap { BluetoothLEDevice(peripheral: $0) }

        bluetoothLEDelegate.central.stopScan()
        bluetoothLEDelegate.foundPeripheral = []

        activeTask = nil

        return devices
    }

    activeTask = task

    return try await task.value

}
...

作者特别呼吁注意演员的使用​​。据我了解，这是为了避免重复调用activeTask时的数据竞争scan()。我的理解正确吗？谢谢您的帮助。