Add demo for CLH

src/main/java/threaddemo/lock/CLH.java

@@ -0,0 +1,30 @@
+package threaddemo.lock;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * demo class for CLH. code from
+ * <a href="https://mp.weixin.qq.com/s/jEx-4XhNGOFdCo4Nou5tqg">Java AQS 核心数据结构-CLH 锁</a>
+ * This is only for demo, do not run the code this node class is not workable
+ */
+public class CLH {
+    private final ThreadLocal<Node> node = ThreadLocal.withInitial(Node::new);
+    private final AtomicReference<Node> tail = new AtomicReference<>(new Node());
+
+    private static class Node {
+        private volatile boolean locked;
+    }
+
+    private void lock() {
+        Node node = this.node.get();
+        node.locked = true;
+        Node pre = this.tail.getAndSet(node);
+        while (!pre.locked) ;
+    }
+
+    private void unlock() {
+        final Node node = this.node.get();
+        node.locked = false;
+        this.node.set(new Node());
+    }
+}