AtomicReference İle Stack Gerçekleştirimi

Örnek

Şöyle yaparız. Burada bir Stack gerçekleştirimi var ve head ve next değerleri atanıyor

public class MyConcurrentStack<T> {

  private AtomicReference<Node> head = new AtomicReference<Node>();

  public void push(T t) {
    if (t == null) {
      return;
    }
    Node<T> n = new Node<T>(t);
    Node<T> current;

    do {
      current = head.get();
      n.setNext(current);
    } while (!head.compareAndSet(current, n));
  }

  public T pop() {
    Node<T> currentHead = null;
    Node<T> futureHead = null;
    do {
      currentHead = head.get();
      if (currentHead == null) {
        return null;
      }
      futureHead = currentHead.next;
    } while (!head.compareAndSet(currentHead, futureHead));

    return currentHead.data;
  }
  
}

Örnek

Elimizde şöyle bir kod olsun

public class StackNode<T> {
  T data;
  StackNode next;

  public StackNode(T t) {
    data = t;
    next = null;
  }
}

Şöyle yaparız

public class AtomicStack<T> {
  private final AtomicReference<StackNode<T>> head = new AtomicReference<>();
  private final AtomicInteger count = new AtomicInteger(0);

  public int getCount() {
    return count.get();
  }
  public T pop() {
    StackNode<T> currentStackHead;
    StackNode<T> newStackHead;
    while(true) {
      currentStackHead =  head.get();
      if(currentStackHead == null){
        break;
      }
      newStackHead = currentStackHead.next;
      if(head.compareAndSet(currentStackHead, newStackHead)) {
        break;
      } else {
        LockSupport.parkNanos(1);
      }
    }
    count.decrementAndGet();
    return currentStackHead != null ? currentStackHead.data: null;
  }
  public void push(T obj) {
    StackNode<T> newStackNode = new StackNode<>(obj);
    while (true) {
      StackNode<T> currentHead = head.get();
      newStackNode.next = currentHead;
      if (head.compareAndSet(currentHead, newStackNode)) {
        break;
      } else {
        LockSupport.parkNanos(1);
      }
    }
    count.incrementAndGet();
  }
}