@Override
  public E peek() {
    if (count.get() == 0) {
      return null;
    }
    final ReentrantLock takeLock = this.takeLock;
    takeLock.lock();
    try {
      Node<E> first = head.next;
      if (first == null) {
        return null;
      } else {
        return first.item;
      }
    } finally {
      takeLock.unlock();
    }
  }
Inserts the specified element at the tail of this queue if it is possible to do so immediately
without exceeding the queue's capacity, returning {@code true} upon success and {@code false}
if this queue is full. When using a capacity-restricted queue, this method is generally
preferable to method {@link BlockingQueue#add add}, which can fail to insert an element only by
throwing an exception.

@throws NullPointerException if the specified element is null
geode-core/src/main/java/org/apache/geode/internal/cache/ForceableLinkedBlockingQueue.java