银行受理业务窗口Thread = null
state = 1
Thread = nullwaitState = 0哨兵节点
next
下面虚线是模拟银行的等候区，每个线程就是一个顾客
HeadTail
prev
Thread = ThreadBwaitState = 0
三个顾客来银行办理业务，类似三个线程。ThreadC
窗口每次只能服务一个，初始没人
AQS = state + CLH队列
state = 0
银行受理业务窗口Thread = ThreadA
三个顾客来银行办理业务，类似三个线程。ThreadAThreadBThreadC
Thread = ThreadCwaitState = 0
