浅谈Java(SpringBoot)基于zookeeper的分布式锁实现

Z时代
2024-01-10
分类：综合

通过zookeeper实现分布式锁

1、创建zookeeper的client

首先通过CuratorFrameworkFactory创建一个连接zookeeper的连接CuratorFramework client


public class CuratorFactoryBean implements FactoryBean<CuratorFramework>, InitializingBean, DisposableBean {
 private static final Logger LOGGER = LoggerFactory.getLogger(ContractFileInfoController.class);
 private String connectionString;
 private int sessionTimeoutMs;
 private int connectionTimeoutMs;
 private RetryPolicy retryPolicy;
 private CuratorFramework client;
 public CuratorFactoryBean(String connectionString) {
  this(connectionString, 500, 500);
 }
 public CuratorFactoryBean(String connectionString, int sessionTimeoutMs, int connectionTimeoutMs) {
  this.connectionString = connectionString;
  this.sessionTimeoutMs = sessionTimeoutMs;
  this.connectionTimeoutMs = connectionTimeoutMs;
 }
 @Override
 public void destroy() throws Exception {
  LOGGER.info("Closing curator framework...");
  this.client.close();
  LOGGER.info("Closed curator framework.");
 }
 @Override
 public CuratorFramework getObject() throws Exception {
  return this.client;
 }
 @Override
 public Class<?> getObjectType() {
   return this.client != null ? this.client.getClass() : CuratorFramework.class;
 }
 @Override
 public boolean isSingleton() {
  return true;
 }
 @Override
 public void afterPropertiesSet() throws Exception {
  if (StringUtils.isEmpty(this.connectionString)) {
   throw new IllegalStateException("connectionString can not be empty.");
  } else {
   if (this.retryPolicy == null) {
    this.retryPolicy = new ExponentialBackoffRetry(1000, 2147483647, 180000);
   }
   this.client = CuratorFrameworkFactory.newClient(this.connectionString, this.sessionTimeoutMs, this.connectionTimeoutMs, this.retryPolicy);
   this.client.start();
   this.client.blockUntilConnected(30, TimeUnit.MILLISECONDS);
  }
 }
 public void setConnectionString(String connectionString) {
  this.connectionString = connectionString;
 }
 public void setSessionTimeoutMs(int sessionTimeoutMs) {
  this.sessionTimeoutMs = sessionTimeoutMs;
 }
 public void setConnectionTimeoutMs(int connectionTimeoutMs) {
  this.connectionTimeoutMs = connectionTimeoutMs;
 }
 public void setRetryPolicy(RetryPolicy retryPolicy) {
  this.retryPolicy = retryPolicy;
 }
 public void setClient(CuratorFramework client) {
  this.client = client;
 }
}

2、封装分布式锁

根据CuratorFramework创建InterProcessMutex（分布式可重入排它锁）对一行数据进行上锁


 public InterProcessMutex(CuratorFramework client, String path) {
  this(client, path, new StandardLockInternalsDriver());
 }

使用 acquire方法

1、acquire() :入参为空，调用该方法后，会一直堵塞，直到抢夺到锁资源，或者zookeeper连接中断后，上抛异常。

2、acquire(long time, TimeUnit unit)：入参传入超时时间、单位，抢夺时，如果出现堵塞，会在超过该时间后，返回false。


 public void acquire() throws Exception {
  if (!this.internalLock(-1L, (TimeUnit)null)) {
   throw new IOException("Lost connection while trying to acquire lock: " + this.basePath);
  }
 }
 public boolean acquire(long time, TimeUnit unit) throws Exception {
  return this.internalLock(time, unit);
 }

释放锁 mutex.release();


public void release() throws Exception {
  Thread currentThread = Thread.currentThread();
  InterProcessMutex.LockData lockData = (InterProcessMutex.LockData)this.threadData.get(currentThread);
  if (lockData == null) {
   throw new IllegalMonitorStateException("You do not own the lock: " + this.basePath);
  } else {
   int newLockCount = lockData.lockCount.decrementAndGet();
   if (newLockCount <= 0) {
    if (newLockCount < 0) {
     throw new IllegalMonitorStateException("Lock count has gone negative for lock: " + this.basePath);
    } else {
     try {
      this.internals.releaseLock(lockData.lockPath);
     } finally {
      this.threadData.remove(currentThread);
     }
    }
   }
  }
 }

封装后的DLock代码

1、调用InterProcessMutex processMutex = dLock.mutex(path);

2、手动释放锁processMutex.release();

3、需要手动删除路径dLock.del(path);

推荐使用：

都是函数式编程

在业务代码执行完毕后会释放锁和删除path

1、这个有返回结果

public T mutex(String path, ZkLockCallback zkLockCallback, long time, TimeUnit timeUnit)

2、这个无返回结果

public void mutex(String path, ZkVoidCallBack zkLockCallback, long time, TimeUnit timeUnit)


public class DLock {
 private final Logger logger;
 private static final long TIMEOUT_D = 100L;
 private static final String ROOT_PATH_D = "/dLock";
 private String lockRootPath;
 private CuratorFramework client;
 public DLock(CuratorFramework client) {
  this("/dLock", client);
 }
 public DLock(String lockRootPath, CuratorFramework client) {
  this.logger = LoggerFactory.getLogger(DLock.class);
  this.lockRootPath = lockRootPath;
  this.client = client;
 }
 public InterProcessMutex mutex(String path) {
  if (!StringUtils.startsWith(path, "/")) {
   path = Constant.keyBuilder(new Object[]{"/", path});
  }
  return new InterProcessMutex(this.client, Constant.keyBuilder(new Object[]{this.lockRootPath, "", path}));
 }
 public <T> T mutex(String path, ZkLockCallback<T> zkLockCallback) throws ZkLockException {
  return this.mutex(path, zkLockCallback, 100L, TimeUnit.MILLISECONDS);
 }
 public <T> T mutex(String path, ZkLockCallback<T> zkLockCallback, long time, TimeUnit timeUnit) throws ZkLockException {
  String finalPath = this.getLockPath(path);
  InterProcessMutex mutex = new InterProcessMutex(this.client, finalPath);
  try {
   if (!mutex.acquire(time, timeUnit)) {
    throw new ZkLockException("acquire zk lock return false");
   }
  } catch (Exception var13) {
   throw new ZkLockException("acquire zk lock failed.", var13);
  }
  T var8;
  try {
   var8 = zkLockCallback.doInLock();
  } finally {
   this.releaseLock(finalPath, mutex);
  }
  return var8;
 }
 private void releaseLock(String finalPath, InterProcessMutex mutex) {
  try {
   mutex.release();
   this.logger.info("delete zk node path:{}", finalPath);
   this.deleteInternal(finalPath);
  } catch (Exception var4) {
   this.logger.error("dlock", "release lock failed, path:{}", finalPath, var4);
//   LogUtil.error(this.logger, "dlock", "release lock failed, path:{}", new Object[]{finalPath, var4});
  }
 }
 public void mutex(String path, ZkVoidCallBack zkLockCallback, long time, TimeUnit timeUnit) throws ZkLockException {
  String finalPath = this.getLockPath(path);
  InterProcessMutex mutex = new InterProcessMutex(this.client, finalPath);
  try {
   if (!mutex.acquire(time, timeUnit)) {
    throw new ZkLockException("acquire zk lock return false");
   }
  } catch (Exception var13) {
   throw new ZkLockException("acquire zk lock failed.", var13);
  }
  try {
   zkLockCallback.response();
  } finally {
   this.releaseLock(finalPath, mutex);
  }
 }
 public String getLockPath(String customPath) {
  if (!StringUtils.startsWith(customPath, "/")) {
   customPath = Constant.keyBuilder(new Object[]{"/", customPath});
  }
  String finalPath = Constant.keyBuilder(new Object[]{this.lockRootPath, "", customPath});
  return finalPath;
 }
 private void deleteInternal(String finalPath) {
  try {
   ((ErrorListenerPathable)this.client.delete().inBackground()).forPath(finalPath);
  } catch (Exception var3) {
   this.logger.info("delete zk node path:{} failed", finalPath);
  }
 }
 public void del(String customPath) {
  String lockPath = "";
  try {
   lockPath = this.getLockPath(customPath);
   ((ErrorListenerPathable)this.client.delete().inBackground()).forPath(lockPath);
  } catch (Exception var4) {
   this.logger.info("delete zk node path:{} failed", lockPath);
  }
 }
}


@FunctionalInterface
public interface ZkLockCallback<T> {
 T doInLock();
}
@FunctionalInterface
public interface ZkVoidCallBack {
 void response();
}
public class ZkLockException extends Exception {
 public ZkLockException() {
 }
 public ZkLockException(String message) {
  super(message);
 }
 public ZkLockException(String message, Throwable cause) {
  super(message, cause);
 }
}

配置CuratorConfig


@Configuration
public class CuratorConfig {
 @Value("${zk.connectionString}")
 private String connectionString;
 @Value("${zk.sessionTimeoutMs:500}")
 private int sessionTimeoutMs;
 @Value("${zk.connectionTimeoutMs:500}")
 private int connectionTimeoutMs;
 @Value("${zk.dLockRoot:/dLock}")
 private String dLockRoot;
 @Bean
 public CuratorFactoryBean curatorFactoryBean() {
  return new CuratorFactoryBean(connectionString, sessionTimeoutMs, connectionTimeoutMs);
 }
 @Bean
 @Autowired
 public DLock dLock(CuratorFramework client) {
  return new DLock(dLockRoot, client);
 }
}

测试代码


@RestController
@RequestMapping("/dLock")
public class LockController {
 @Autowired
 private DLock dLock;
 @RequestMapping("/lock")
 public Map testDLock(String no){
  final String path = Constant.keyBuilder("/test/no/", no);
  Long mutex=0l;
  try {
   System.out.println("在拿锁："+path+System.currentTimeMillis());
    mutex = dLock.mutex(path, () -> {
    try {
     System.out.println("拿到锁了" + System.currentTimeMillis());
     Thread.sleep(10000);
     System.out.println("操作完成了" + System.currentTimeMillis());
    } finally {
     return System.currentTimeMillis();
    }
   }, 1000, TimeUnit.MILLISECONDS);
  } catch (ZkLockException e) {
   System.out.println("拿不到锁呀"+System.currentTimeMillis());
  }
  return Collections.singletonMap("ret",mutex);
 }
 @RequestMapping("/dlock")
 public Map testDLock1(String no){
  final String path = Constant.keyBuilder("/test/no/", no);
  Long mutex=0l;
  try {
   System.out.println("在拿锁："+path+System.currentTimeMillis());
   InterProcessMutex processMutex = dLock.mutex(path);
   processMutex.acquire();
   System.out.println("拿到锁了" + System.currentTimeMillis());
   Thread.sleep(10000);
   processMutex.release();
   System.out.println("操作完成了" + System.currentTimeMillis());
  } catch (ZkLockException e) {
   System.out.println("拿不到锁呀"+System.currentTimeMillis());
   e.printStackTrace();
  }catch (Exception e){
   e.printStackTrace();
  }
  return Collections.singletonMap("ret",mutex);
 }
 @RequestMapping("/del")
 public Map delDLock(String no){
  final String path = Constant.keyBuilder("/test/no/", no);
  dLock.del(path);
  return Collections.singletonMap("ret",1);
 }
}