/** {@inheritDoc} */
@Override
protected Collection<E> dequeue0(int cnt) {
WindowHolder tup = ref.get();
AtomicInteger size = tup.size();
Collection<T> evts = tup.collection();
Collection<E> resCol = new ArrayList<>(cnt);
while (true) {
int curSize = size.get();
if (curSize > 0) {
if (size.compareAndSet(curSize, curSize - 1)) {
E res = pollInternal(evts, tup.set());
if (res != null) {
resCol.add(res);
if (resCol.size() >= cnt) return resCol;
} else {
size.incrementAndGet();
return resCol;
}
}
} else return resCol;
}
}
/**
* Poll evicted internal implementation.
*
* @return Evicted element.
*/
@Nullable
private E pollEvictedInternal() {
WindowHolder tup = ref.get();
AtomicInteger size = tup.size();
while (true) {
int curSize = size.get();
if (curSize > maxSize) {
if (size.compareAndSet(curSize, curSize - 1)) {
E evt = pollInternal(tup.collection(), tup.set());
if (evt != null) return evt;
else {
// No actual events in queue, it means that other thread is just adding event.
// return null as it is a concurrent add call.
size.incrementAndGet();
return null;
}
}
} else return null;
}
}