七周七并发模型笔记

class ConcurrentSortedList {
	private class Node {
		int value;
		Node prev;
		Node next;
		ReentrantLock lock = new ReentrantLock();

		Node() {}

		Node(int value, Node prev, Node next) {
			this.value = value; this.prev = prev; this.next = next;
		}
	}

	private final Node head;
	private final Node tail;

	public ConcurrentSortedList() {
		head = new Node(); tail = new Node();
		head.next = tail; tail.prev = head;
	}

	public void insert(int value) {
		Node current = head;
		current.lock.lock();
		Node next = current.next;
		try {
			while (true) {
				next.lock.lock();
				try {
					if (next == tail || next.value < value) {
						Node node = new Node(value, current, next);
						next.prev = node;
						current.next = node;
						return;
					}
				} finally { current.lock.unlock(); }
				current = next;
				next = current.next;
			}
		} finally { next.lock.unlock(); }
	}
}

public int size() {
  Node current = tail;
  int count = 0;

  while (current.prev != head) {
    ReentrantLock lock = current.lock;
    lock.lock();
    try {
      ++count;
      current = current.prev;
  } finally { lock.unlock(); }
}

return count;
}

B.prev = C  //(1)
C.prev = A

C.prev = A   // (1)
B.prev = C   // (2)