这才是图文并茂：我写了 1 万多字，就是为了让你了解 AQS 是怎么运行的

static final class Node {
        /** 表示共享模式下等待的Node */
        static final Node SHARED = new Node();
        /** 表示独占模式下等待的mode */
        static final Node EXCLUSIVE = null;

        /** 下面几个为waitStatus的具体值 */
        static final int CANCELLED =  1;
        static final int SIGNAL    = -1;
        static final int CONDITION = -2;
        static final int PROPAGATE = -3;
    
        volatile int waitStatus;
        
         /** 表示前面的结点 */
        volatile Node prev;
         /** 表示后面的结点 */
        volatile Node next;
         /**当前结点装载的线程，初始化时被创建，使用后会置空*/
        volatile Thread thread;
         /**链接到下一个节点的等待条件，用到Condition的时候会使用到*/
        Node nextWaiter;
    
    }



private transient volatile Node head;
private transient volatile Node tail;   



final void lock() {
 if (compareAndSetState(0, 1))
  setExclusiveOwnerThread(Thread.currentThread());
 else
  acquire(1);
}



public final void acquire(int arg) {
 if (!tryAcquire(arg) &&
  acquireQueued(addWaiter(Node.EXCLUSIVE), arg))
  selfInterrupt();
}



protected final boolean tryAcquire(int acquires) {
 return nonfairTryAcquire(acquires);
}

final boolean nonfairTryAcquire(int acquires) {
 final Thread current = Thread.currentThread();
 int c = getState();
 if (c == 0) {
  if (compareAndSetState(0, acquires)) {
   setExclusiveOwnerThread(current);
   return true;
  }
 }
 else if (current == getExclusiveOwnerThread()) {
  int nextc = c + acquires;
  if (nextc < 0) // overflow
   throw new Error("Maximum lock count exceeded");
  setState(nextc);
  return true;
 }
 return false;
}



private Node addWaiter(Node mode) {
 Node node = new Node(Thread.currentThread(), mode);
 // Try the fast path of enq; backup to full enq on failure
 Node pred = tail;
 if (pred != null) {
  node.prev = pred;
  if (compareAndSetTail(pred, node)) {
   pred.next = node;
   return node;
  }
 }
 enq(node);
 return node;
}



private Node enq(final Node node) {
 // CAS"自旋"，直到成功加入队尾
    for (;;) {
        Node t = tail;
        if (t == null) {
         // 队列为空，初始化一个Node结点作为Head结点，并将tail结点也指向它
            if (compareAndSetHead(new Node()))
                tail = head;
        } else {
         // 把当前结点插入队列尾部
            node.prev = t;
            if (compareAndSetTail(t, node)) {
                t.next = node;
                return t;
            }
        }
    }
}



final boolean acquireQueued(final Node node, int arg) {
 boolean failed = true;
 try {
  // 标记是否会被中断
  boolean interrupted = false;
  // CAS自旋
  for (;;) {
   // 获取当前结点的前结点
   final Node p = node.predecessor();
   if (p == head && tryAcquire(arg)) {
    setHead(node);
    p.next = null; // help GC
    failed = false;
    return interrupted;
   }
   if (shouldParkAfterFailedAcquire(p, node) &&
    parkAndCheckInterrupt())
    interrupted = true;
  }
 } finally {
  if (failed)
   // 获取锁失败，则将此线程对应的node的waitStatus改为CANCEL
   cancelAcquire(node);
 }
}
private static boolean shouldParkAfterFailedAcquire(Node pred, Node node) {
 int ws = pred.waitStatus;
 if (ws == Node.SIGNAL)
  // 前驱结点等待状态为"SIGNAL"，那么自己就可以安心等待被唤醒了
  return true;
 if (ws > 0) {
  /*
   * 前驱结点被取消了，通过循环一直往前找，直到找到等待状态有效的结点(等待状态值小于等于0) ，
   * 然后排在他们的后边，至于那些被当前Node强制"靠后"的结点，因为已经被取消了，也没有引用链，
   * 就等着被GC了
   */
  do {
   node.prev = pred = pred.prev;
  } while (pred.waitStatus > 0);
  pred.next = node;
 } else {
  // 如果前驱正常，那就把前驱的状态设置成SIGNAL
  compareAndSetWaitStatus(pred, ws, Node.SIGNAL);
 }
 return false;
}
private final boolean parkAndCheckInterrupt() {
 LockSupport.park(this);
 return Thread.interrupted();
}



public final boolean release(int arg) {
 if (tryRelease(arg)) {
  Node h = head;
  if (h != null && h.waitStatus != 0)
   unparkSuccessor(h);
  return true;
 }
 return false;
}



protected final boolean tryRelease(int releases) {
 int c = getState() - releases;
 if (Thread.currentThread() != getExclusiveOwnerThread())
  throw new IllegalMonitorStateException();
 boolean free = false;
 if (c == 0) {
  free = true;
  setExclusiveOwnerThread(null);
 }
 setState(c);
 return free;
}



private void unparkSuccessor(Node node) {
    int ws = node.waitStatus;
    if (ws < 0)
     //将head结点的状态置为0
        compareAndSetWaitStatus(node, ws, 0);
 //找到下一个需要唤醒的结点s
    Node s = node.next;
    //如果为空或已取消
    if (s == null || s.waitStatus > 0) {
        s = null;
        // 从后向前，直到找到等待状态小于0的结点，前面说了，结点waitStatus小于0时才有效
        for (Node t = tail; t != null && t != node; t = t.prev) 
            if (t.waitStatus <= 0)
                s = t;
    }
    // 找到有效的结点，直接唤醒
    if (s != null)
        LockSupport.unpark(s.thread);//唤醒
}



for (;;) {
 // 获取当前结点的前结点
 final Node p = node.predecessor();
 if (p == head && tryAcquire(arg)) {
  setHead(node);
  p.next = null; // help GC
  failed = false;
  return interrupted;
 }
 if (shouldParkAfterFailedAcquire(p, node) &&
  parkAndCheckInterrupt())
  interrupted = true;
}



public final void acquireShared(int arg) {
 if (tryAcquireShared(arg) < 0)
  doAcquireShared(arg);
}



private void doAcquireShared(int arg) {
 // 加入队列尾部
 final Node node = addWaiter(Node.SHARED);
 boolean failed = true;
 try {
  boolean interrupted = false;
  // CAS自旋
  for (;;) {
   final Node p = node.predecessor();
   // 判断前驱结点是否是head
   if (p == head) {
    // 尝试获取一定数量的锁
    int r = tryAcquireShared(arg);
    if (r >= 0) {
     // 获取锁成功，而且还有剩余资源，就设置当前结点为head，并继续唤醒下一个线程
     setHeadAndPropagate(node, r);
     // 让前驱结点去掉引用链，方便被GC
     p.next = null; // help GC
     if (interrupted)
      selfInterrupt();
     failed = false;
     return;
    }
   }
   // 跟独占模式一样，改前驱结点waitStatus为-1，并且当前线程挂起，等待被唤醒
   if (shouldParkAfterFailedAcquire(p, node) &&
    parkAndCheckInterrupt())
    interrupted = true;
  }
 } finally {
  if (failed)
   cancelAcquire(node);
 }
}

private void setHeadAndPropagate(Node node, int propagate) {
    Node h = head;
    // head指向自己
    setHead(node);
     // 如果还有剩余量，继续唤醒下一个邻居线程
    if (propagate > 0 || h == null || h.waitStatus < 0) {
        Node s = node.next;
        if (s == null || s.isShared())
            doReleaseShared();
    }
}



public final boolean releaseShared(int arg) {
 if (tryReleaseShared(arg)) {
  doReleaseShared();
  return true;
 }
 return false;
}



private void doReleaseShared() {
 for (;;) {
  // 获取等待队列中的head结点
  Node h = head;
  if (h != null && h != tail) {
   int ws = h.waitStatus;
   // head结点waitStatus = -1,唤醒下一个结点对应的线程
   if (ws == Node.SIGNAL) {
    if (!compareAndSetWaitStatus(h, Node.SIGNAL, 0))
     continue;            // loop to recheck cases
    // 唤醒后继结点
    unparkSuccessor(h);
   }
   else if (ws == 0 &&
      !compareAndSetWaitStatus(h, 0, Node.PROPAGATE))
    continue;                // loop on failed CAS
  }
  if (h == head)                   // loop if head changed
   break;
 }
}



public class ConditionDemo {

    public static void main(String[] args) {
        ReentrantLock lock = new ReentrantLock();
        Condition condition = lock.newCondition();
        Thread tA = new Thread(() -> {
            lock.lock();
            try {
                System.out.println("线程A加锁成功");
                System.out.println("线程A执行await被挂起");
                condition.await();
                System.out.println("线程A被唤醒成功");
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                lock.unlock();
                System.out.println("线程A释放锁成功");
            }
        });

        Thread tB = new Thread(() -> {
            lock.lock();
            try {
                System.out.println("线程B加锁成功");
                condition.signal();
                System.out.println("线程B唤醒线程A");
            } finally {
                lock.unlock();
                System.out.println("线程B释放锁成功");
            }
        });
        tA.start();
        tB.start();
    }
}



线程A加锁成功
线程A执行await被挂起
线程B加锁成功
线程B唤醒线程A
线程B释放锁成功
线程A被唤醒成功
线程A释放锁成功



/** First node of condition queue. */
private transient Node firstWaiter;
/** Last node of condition queue. */
private transient Node lastWaiter;



public final void await() throws InterruptedException {
    if (Thread.interrupted())
        throw new InterruptedException();
    // 将当前线程加入到等待队列中
    Node node = addConditionWaiter();
    // 完全释放占有的资源，并返回资源数
    int savedState = fullyRelease(node);
    int interruptMode = 0;
    // 循环判断当前结点是不是在Condition的队列中，是的话挂起
    while (!isOnSyncQueue(node)) {
        LockSupport.park(this);
        if ((interruptMode = checkInterruptWhileWaiting(node)) != 0)
            break;
    }
    if (acquireQueued(node, savedState) && interruptMode != THROW_IE)
        interruptMode = REINTERRUPT;
    if (node.nextWaiter != null) // clean up if cancelled
        unlinkCancelledWaiters();
    if (interruptMode != 0)
        reportInterruptAfterWait(interruptMode);
}



private Node addConditionWaiter() {
    Node t = lastWaiter;
    // If lastWaiter is cancelled, clean out.
    if (t != null && t.waitStatus != Node.CONDITION) {
        unlinkCancelledWaiters();
        t = lastWaiter;
    }
    Node node = new Node(Thread.currentThread(), Node.CONDITION);
    if (t == null)
        firstWaiter = node;
    else
        t.nextWaiter = node;
    lastWaiter = node;
    return node;
}



while (!isOnSyncQueue(node)) {
 LockSupport.park(this);
 if ((interruptMode = checkInterruptWhileWaiting(node)) != 0)
  break;
}



public final void signal() {
    if (!isHeldExclusively())
        throw new IllegalMonitorStateException();
    Node first = firstWaiter;
    if (first != null)
        doSignal(first);
}



private void doSignal(Node first) {
 // 循环，从队列一直往后找不为空的首结点
    do {
        if ( (firstWaiter = first.nextWaiter) == null)
            lastWaiter = null;
        first.nextWaiter = null;
    } while (!transferForSignal(first) &&
             (first = firstWaiter) != null);
}

final boolean transferForSignal(Node node) {
 // CAS循环，将结点的waitStatus改为0
    if (!compareAndSetWaitStatus(node, Node.CONDITION, 0))
        return false;
 // 上面已经分析过，此方法会把当前结点加入到等待队列中，并返回前驱结点
    Node p = enq(node);
    int ws = p.waitStatus;
    if (ws > 0 || !compareAndSetWaitStatus(p, ws, Node.SIGNAL))
        LockSupport.unpark(node.thread);
    return true;
}




while (!isOnSyncQueue(node)) {
        LockSupport.park(this);
        if ((interruptMode = checkInterruptWhileWaiting(node)) != 0)
            break;
    }
    if (acquireQueued(node, savedState) && interruptMode != THROW_IE)
        interruptMode = REINTERRUPT;
    if (node.nextWaiter != null) // clean up if cancelled
        unlinkCancelledWaiters();
    if (interruptMode != 0)
        reportInterruptAfterWait(interruptMode);