记一次 "排它锁" 和 "自旋锁" 的简单实现

记一次排它锁和自旋锁的简单实现

• 定义一个lock接口

  public interface PutMessageLock {
      void lock();
  
      void unlock();
  }
  

• 排它锁实现

  • 使用java自带的 ReentrantLock即可

  public class PutMessageReentrantLock implements PutMessageLock {
      private ReentrantLock putMessageNormalLock = new ReentrantLock(); // NonfairSync
  
      @Override
      public void lock() {
          putMessageNormalLock.lock();
      }
  
      @Override
      public void unlock() {
          putMessageNormalLock.unlock();
      }
  }
  

• 自旋锁实现

  • 使用 cas + 循环 来实现

  public class PutMessageSpinLock implements PutMessageLock {
      //true: Can lock, false : in lock.
      private AtomicBoolean putMessageSpinLock = new AtomicBoolean(true);
  
      @Override
      public void lock() {
          boolean flag;
          do {
              flag = this.putMessageSpinLock.compareAndSet(true, false);
          }
          while (!flag);
      }
  
      @Override
      public void unlock() {
          this.putMessageSpinLock.compareAndSet(false, true);
      }
  }
  

----------------------------------------- 广告时间 -----------------------------------------

各位看官,  欢迎关注公众号，每天推送有意思的小东西哦！！！