/**
* Insert the specified {@link QueueElement} element into the queue.
*
* @param queueElement the {@link QueueElement} element to add.
* @param ignoreSize if the queue is bound to a maximum size and the maximum size is reached, this
* parameter (if set to <tt>true</tt>) allows to ignore the maximum size and add the element
* to the queue.
* @return <tt>true</tt> if the element has been inserted, <tt>false</tt> if the element was not
* inserted (the queue has reached its maximum size).
* @throws NullPointerException if the specified element is null
*/
boolean offer(QueueElement<E> queueElement, boolean ignoreSize) {
if (queueElement == null) {
throw new NullPointerException("queueElement is NULL");
}
if (queueElement.getPriority() < 0 || queueElement.getPriority() >= priorities) {
throw new IllegalArgumentException("priority out of range: " + queueElement);
}
if (queueElement.inQueue) {
throw new IllegalStateException("queueElement already in a queue: " + queueElement);
}
if (!ignoreSize && currentSize != null && currentSize.get() >= maxSize) {
return false;
}
boolean accepted;
lock.lock();
try {
accepted = queues[queueElement.getPriority()].offer(queueElement);
debug(
"offer([{0}]), to P[{1}] delay[{2}ms] accepted[{3}]",
queueElement.getElement().toString(),
queueElement.getPriority(),
queueElement.getDelay(TimeUnit.MILLISECONDS),
accepted);
if (accepted) {
if (currentSize != null) {
currentSize.incrementAndGet();
}
queueElement.inQueue = true;
}
} finally {
lock.unlock();
}
return accepted;
}
/**
* Retrieve and remove the head of this queue, or return <tt>null</tt> if this queue has no
* elements with an expired delay.
*
* <p>The retrieved element is the oldest one from the highest priority sub-queue.
*
* <p>Invocations to this method run the anti-starvation (once every interval check).
*
* @return the head of this queue, or <tt>null</tt> if this queue has no elements with an expired
* delay.
*/
@Override
public QueueElement<E> poll() {
lock.lock();
try {
antiStarvation();
QueueElement<E> e = null;
int i = priorities;
for (; e == null && i > 0; i--) {
e = queues[i - 1].poll();
}
if (e != null) {
if (currentSize != null) {
currentSize.decrementAndGet();
}
e.inQueue = false;
debug("poll(): [{0}], from P[{1}]", e.getElement().toString(), i);
}
return e;
} finally {
lock.unlock();
}
}