虽然很少和AQS直接打交道，但是Java并发工具的底层基础，所以还是要了解队列同步器的运行机制

直接看源代码

AbstractQueuedSynchronizer 内部有两个内部类:Node和ConditionObject,是aqs的基石。

  1. public abstract class AbstractQueuedSynchronizer extends AbstractOwnableSynchronizer {
  3.     public class ConditionObject implements Condition {
  4.          private transient Node firstWaiter;
  5.          private transient Node lastWaiter;
  7.     }
  9.     static final class Node {
  10.         static final Node SHARED = new Node();
  11.         volatile int waitStatus;
  12.         volatile Node prev;
  13.         volatile Node next;
  14.         volatile Thread thread;
  15.         Node nextWaiter;
  17.         Node() {    // Used to establish initial head or SHARED marker
  18.         }
  20.         Node(Thread thread, Node mode) {     // Used by addWaiter
  21.             this.nextWaiter = mode;
  22.             this.thread = thread;
  23.         }
  25.         Node(Thread thread, int waitStatus) { // Used by Condition
  26.             this.waitStatus = waitStatus;
  27.             this.thread = thread;
  28.         }
  29.     }
  37. }