OSUnfairLock Swift

OSUnfairLock.swift

private final class OSUnfairLock {
    private let pointer: os_unfair_lock_t

    init() {
        self.pointer = .allocate(capacity: 1)
        self.pointer.initialize(to: os_unfair_lock())
    }

    deinit {
        self.pointer.deinitialize(count: 1)
        self.pointer.deallocate()
    }

    func lock() {
        os_unfair_lock_lock(self.pointer)
    }

    func unlock() {
        os_unfair_lock_unlock(self.pointer)
    }
}

final class ThreadSafe<T> {
    private let lock = OSUnfairLock()

    private var _value: T

    init(_ value: T) {
        self._value = value
    }

    var value: T {
        self.lock.lock(); defer { self.lock.unlock() }
        return self._value
    }

    @discardableResult
    func mutate<U>(_ action: (inout T) -> U) -> U {
        self.lock.lock(); defer { self.lock.unlock() }
        return action(&self._value)
    }
}