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| public E next() { final E e = nextItem; if (e == null) throw new NoSuchElementException(); final ReentrantLock lock = ArrayBlockingQueue.this.lock; lock.lock(); try { if (!isDetached()) { incorporateDequeues(); } lastRet = nextIndex; final int cursor = this.cursor; if (cursor >= 0) { nextItem = itemAt(nextIndex = cursor); this.cursor = incCursor(cursor); } else { nextIndex = NONE; nextItem = null; if (lastRet == REMOVED) { detach(); } } } finally { lock.unlock(); } return e; }
private void detach() { if (prevTakeIndex >= 0) { prevTakeIndex = DETACHED; itrs.doSomeSweeping(true); } }
private void incorporateDequeues() { final int cycles = itrs.cycles; final int takeIndex = ArrayBlockingQueue.this.takeIndex; final int prevCycles = this.prevCycles; final int prevTakeIndex = this.prevTakeIndex;
if (cycles != prevCycles || takeIndex != prevTakeIndex) { final int len = items.length; long dequeues = (long) (cycles - prevCycles) * len + (takeIndex - prevTakeIndex);
if (invalidated(lastRet, prevTakeIndex, dequeues, len)) { lastRet = REMOVED; } if (invalidated(nextIndex, prevTakeIndex, dequeues, len)) { nextIndex = REMOVED; } if (invalidated(cursor, prevTakeIndex, dequeues, len)) { cursor = takeIndex; } if (cursor < 0 && nextIndex < 0 && lastRet < 0) { detach(); } else { this.prevCycles = cycles; this.prevTakeIndex = takeIndex; } }
private boolean invalidated(int index, int prevTakeIndex, long dequeues, int length) { if (index < 0) { return false; } int distance = index - prevTakeIndex; if (distance < 0) { distance += length; } return dequeues > distance; }
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