How to use

AbstractNodeQueue$Node

in

akka.dispatch

public final void add(final T value) {
  final Node<T> n = new Node<T>(value);
  getAndSet(n).setNext(n);
}

/**
 * Pull one item from the queue, returning it within a queue node.
 * 
 * Use this method only from the consumer thread!
 * 
 * @return queue node with element inside if there was one, or null if there was none
 */
@SuppressWarnings("unchecked")
public final Node<T> pollNode() {
 final Node<T> tail = (Node<T>) Unsafe.instance.getObjectVolatile(this, tailOffset);
 Node<T> next = tail.next();
 if (next == null && get() != tail) {
   // if tail != head this is not going to change until producer makes progress
   // we can avoid reading the head and just spin on next until it shows up
   do {
     next = tail.next();
   } while (next == null);
 }
 if (next == null) return null;
 else {
  tail.value = next.value;
  next.value = null;
  Unsafe.instance.putOrderedObject(this, tailOffset, next);
  tail.setNext(null);
  return tail;
 }
}

/**
 * Pull one item from the queue, returning it within a queue node.
 * 
 * Use this method only from the consumer thread!
 * 
 * @return queue node with element inside if there was one, or null if there was none
 */
@SuppressWarnings("unchecked")
public final Node<T> pollNode() {
 final Node<T> tail = (Node<T>) Unsafe.instance.getObjectVolatile(this, tailOffset);
 Node<T> next = tail.next();
 if (next == null && get() != tail) {
   // if tail != head this is not going to change until producer makes progress
   // we can avoid reading the head and just spin on next until it shows up
   do {
     next = tail.next();
   } while (next == null);
 }
 if (next == null) return null;
 else {
  tail.value = next.value;
  next.value = null;
  Unsafe.instance.putOrderedObject(this, tailOffset, next);
  tail.setNext(null);
  return tail;
 }
}

/**
 * This method returns an upper bound on the queue size at the time it
 * starts executing. It may spuriously return smaller values (including
 * zero) if the consumer pulls items out concurrently.
 * 
 * This method can be used from any thread.
 * 
 * @return an upper bound on queue length at some time in the past
 */
@SuppressWarnings("unchecked")
public final int count() {
  int count = 0;
  final Node<T> head = get();
  for(Node<T> n = ((Node<T>) Unsafe.instance.getObjectVolatile(this, tailOffset)).next();
    n != null && count < Integer.MAX_VALUE; 
    n = n.next()) {
   ++count;
   // only iterate up to the point where head was when starting: this is a moving queue!
   if (n == head) break;
  }
  return count;
}

/**
 * This method returns an upper bound on the queue size at the time it
 * starts executing. It may spuriously return smaller values (including
 * zero) if the consumer pulls items out concurrently.
 * 
 * This method can be used from any thread.
 * 
 * @return an upper bound on queue length at some time in the past
 */
@SuppressWarnings("unchecked")
public final int count() {
  int count = 0;
  final Node<T> head = get();
  for(Node<T> n = ((Node<T>) Unsafe.instance.getObjectVolatile(this, tailOffset)).next();
    n != null && count < Integer.MAX_VALUE; 
    n = n.next()) {
   ++count;
   // only iterate up to the point where head was when starting: this is a moving queue!
   if (n == head) break;
  }
  return count;
}

@SuppressWarnings("unchecked")
public final Node<T> pollNode() {
 Node<T> tail;
 Node<T> next;
 for(;;) {
  tail = ((Node<T>)Unsafe.instance.getObjectVolatile(this, tailOffset));
  next = tail.next();
  if (next != null || get() == tail)
   break;
 }
 if (next == null) return null;
 else {
  tail.value = next.value;
  next.value = null;
  Unsafe.instance.putOrderedObject(this, tailOffset, next);
  return tail;
 }
}

@SuppressWarnings("unchecked")
public final Node<T> pollNode() {
 Node<T> tail;
 Node<T> next;
 for(;;) {
  tail = ((Node<T>)Unsafe.instance.getObjectVolatile(this, tailOffset));
  next = tail.next();
  if (next != null || get() == tail)
   break;
 }
 if (next == null) return null;
 else {
  tail.value = next.value;
  next.value = null;
  Unsafe.instance.putOrderedObject(this, tailOffset, next);
  return tail;
 }
}

/**
 * Query the queue tail for the next element without dequeuing it.
 * 
 * Use this method only from the consumer thread!
 * 
 * !!! There is a copy of this code in pollNode() !!!
 * 
 * @return queue node with element inside if there was one, or null if there was none
 */
@SuppressWarnings("unchecked")
protected final Node<T> peekNode() {
  for(;;) {
   final Node<T> tail = ((Node<T>)Unsafe.instance.getObjectVolatile(this, tailOffset));
   final Node<T> next = tail.next();
   if (next != null || get() == tail)
    return next;
  }
}

/**
 * Query the queue tail for the next element without dequeuing it.
 * 
 * Use this method only from the consumer thread!
 * 
 * !!! There is a copy of this code in pollNode() !!!
 * 
 * @return queue node with element inside if there was one, or null if there was none
 */
@SuppressWarnings("unchecked")
protected final Node<T> peekNode() {
  for(;;) {
   final Node<T> tail = ((Node<T>)Unsafe.instance.getObjectVolatile(this, tailOffset));
   final Node<T> next = tail.next();
   if (next != null || get() == tail)
    return next;
  }
}

public final void addNode(final Node<T> n) {
  n.setNext(null);
  getAndSet(n).setNext(n);
}

public final void addNode(final Node<T> n) {
  n.setNext(null);
  getAndSet(n).setNext(n);
}

/**
 * Add an element to the head of the queue, providing the queue node to be used.
 * 
 * This method can be used from any thread.
 * 
 * @param n the node containing the element to be added; both must not be null
 */
public final void addNode(final Node<T> n) {
  n.setNext(null);
  getAndSet(n).setNext(n);
}

protected AbstractNodeQueue() {
  final Node<T> n = new Node<T>();
  _tailDoNotCallMeDirectly = n;
  set(n);
}

@SuppressWarnings("unchecked")
protected final Node<T> peekNode() {
  for(;;) {
   final Node<T> tail = ((Node<T>)Unsafe.instance.getObjectVolatile(this, tailOffset));
   final Node<T> next = tail.next();
   if (next != null || get() == tail)
    return next;
  }
}

/**
 * Add an element to the head of the queue, providing the queue node to be used.
 * 
 * This method can be used from any thread.
 * 
 * @param n the node containing the element to be added; both must not be null
 */
public final void addNode(final Node<T> n) {
  n.setNext(null);
  getAndSet(n).setNext(n);
}

protected AbstractNodeQueue() {
  final Node<T> n = new Node<T>();
  _tailDoNotCallMeDirectly = n;
  set(n);
}

/**
 * Add an element to the head of the queue.
 * 
 * This method can be used from any thread.
 * 
 * @param value the element to be added; must not be null
 */
public final void add(final T value) {
  final Node<T> n = new Node<T>(value);
  getAndSet(n).setNext(n);
}

@SuppressWarnings("unchecked")
protected final Node<T> peekNode() {
  for(;;) {
   final Node<T> tail = ((Node<T>)Unsafe.instance.getObjectVolatile(this, tailOffset));
   final Node<T> next = tail.next();
   if (next != null || get() == tail)
    return next;
  }
}

protected AbstractNodeQueue() {
  final Node<T> n = new Node<T>();
  _tailDoNotCallMeDirectly = n;
  set(n);
}

protected AbstractNodeQueue() {
  final Node<T> n = new Node<T>();
  _tailDoNotCallMeDirectly = n;
  set(n);
}