java中PriorityBlockingQueue的入队

public void put(E e) {

    offer(e); // never need to block

}

public boolean offer(E e) {

    //判断是否为空

    if (e == null)

        throw new NullPointerException();

    //显示锁

    final ReentrantLock lock = this.lock;

    lock.lock();

    //定义临时对象

    int n, cap;

    Object[] array;

    //判断数组是否满了

    while ((n = size) >= (cap = (array = queue).length))

        //数组扩容

        tryGrow(array, cap);

    try {

        //拿到比较器

        Comparator<? super E> cmp = comparator;

        //判断是否有自定义比较器

        if (cmp == null)

            //堆上浮

            siftUpComparable(n, e, array);

        else

            //使用自定义比较器进行堆上浮

            siftUpUsingComparator(n, e, array, cmp);

        //队列长度 +1

        size = n + 1;

        //唤醒休眠的出队线程

        notEmpty.signal();

    } finally {

        //释放锁

        lock.unlock();

    }

    return true;

}