exclusive-access.swift

import Foundation

struct Node {
    var childs: [String] = []
       
    init() {}
    
    mutating func clearChilds() {
        if childs.isEmpty {
            childs.removeAll()
        }
    }
}

var node = Node()
var lock = NSRecursiveLock()
DispatchQueue(label: "queue.test.exclusive-access").async {
    lock.lock()
    node.clearChilds()
    lock.unlock()
}

DispatchQueue(label: "queue.test.exclusive-access.other").async {
    lock.lock()
    node.clearChilds()
    lock.unlock()
}

print("Everything is OK now \\o/")