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redis分布式锁
/**
* @author yujianjian 2019-08-28 17:28
* redis分布式锁实现
*/
@Slf4j
@Service
public class RedisLock {
@Autowired
private StringRedisTemplate redisTemplate;
@Autowired
private DefaultRedisScript<Long> redisScript;
private static final Long SUCCESS = 1L;
/**
* 尝试获取锁,只获取一次
*
* @param lockKey key
* @param value value
* @param expireTime 过期时间-秒
* @return 获取锁的结果
*/
public boolean tryLock(String lockKey, String value, int expireTime) {
try {
return redisTemplate.opsForValue().setIfAbsent(lockKey, value, expireTime, TimeUnit.SECONDS);
// String script = "if redis.call('setNx',KEYS[1],ARGV[1]) then if redis.call('get',KEYS[1])==ARGV[1] then return redis.call('expire',KEYS[1],ARGV[2]) else return 0 end end";
} catch (Exception e) {
log.error("RedisLock|tryLock fail lockKey={}|value={}|expireTime={}", lockKey, value, expireTime, e);
}
return false;
}
/**
* 加锁(指定最大尝试次数)
*
* @param lockKey key
* @param value value
* @param expireTime 过期时间-秒
* @param tryTimes 最大尝试次数
* @param sleepMillis 每两次尝试之间的休眠时间(毫秒)
* @return 获取锁的结果
*/
public boolean getLock(String lockKey, String value, int expireTime, int tryTimes, long sleepMillis) {
boolean result = false;
int count = 0;
while (!result && count <= tryTimes) {
count++;
result = tryLock(lockKey, value, expireTime);
try {
TimeUnit.MILLISECONDS.sleep(sleepMillis);
} catch (InterruptedException e) {
log.error("getLock fail", e);
}
}
return result;
}
/**
* 释放锁
*
* @param lockKey key
* @param value value
* @return 释放锁的结果
*/
public boolean releaseLock(String lockKey, String value) {
try {
String script = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
Long result = redisTemplate.execute(redisScript, Arrays.asList(lockKey, value));
return SUCCESS.equals(result);
} catch (Exception e) {
log.error("RedisLock|releaseLock fail lockKey={}|value={}", lockKey, value, e);
}
return false;
}
@Bean
public DefaultRedisScript<Long> defaultRedisScript() {
DefaultRedisScript<Long> defaultRedisScript = new DefaultRedisScript<>();
defaultRedisScript.setResultType(Long.class);
defaultRedisScript.setScriptText("if redis.call('get', KEYS[1]) == KEYS[2] then return redis.call('del', KEYS[1]) else return 0 end");
return defaultRedisScript;
}
}
zk分布式锁
zk分布式锁实现原理图
zk-dispatcher-lock.png
pom中添加依赖
<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-recipes</artifactId>
<version>4.0.1</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-framework</artifactId>
<version>4.0.1</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
properties添加配置信息
curator:
# 重试次数
retryCount: 5
# 重试间隔时间
elapsedTimeMs: 5000
# zk地址
connectString: 127.0.0.1:2181
# session超时时间
sessionTimeoutMs: 60000
# 连接超时时间
connectionTimeoutMs: 5000
代码中增加连接信息
@Configuration
public class CuratorConfig {
@Value("${curator.retryCount}")
private int retryCount;
@Value("${curator.elapsedTimeMs}")
private int elapsedTimeMs;
@Value("${curator.connectString}")
private String connectString;
@Value("${curator.sessionTimeoutMs}")
private int sessionTimeoutMs;
@Value("${curator.connectionTimeoutMs}")
private int connectionTimeoutMs;
@Bean(initMethod = "start")
public CuratorFramework curatorFramework() {
return CuratorFrameworkFactory.newClient(
connectString,
sessionTimeoutMs,
connectionTimeoutMs,
new RetryNTimes(retryCount, elapsedTimeMs));
}
}
锁的代码实现
/**
* @author yujianjian 2019-08-29 09:44
*/
@Service
@Slf4j
public class DistributedLockByCurator implements InitializingBean {
// zk下的创建的目录
private final static String ROOT_PATH_LOCK = "rootlock";
private CountDownLatch cdl = new CountDownLatch(1);
@Autowired
private CuratorFramework curatorFramework;
/**
* 获取分布式锁
*/
public void acquireLock(String path) {
String keyPath = "/" + ROOT_PATH_LOCK + "/" + path;
while (true) {
try {
curatorFramework
.create()
.creatingParentsIfNeeded()
.withMode(CreateMode.EPHEMERAL)
.withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
.forPath(keyPath);
log.info("acquireLock|success to acquire lock for path:{}", keyPath);
break;
} catch (Exception e) {
log.info("acquireLock|failed to acquire lock for path:{}", keyPath);
log.info("acquireLock|while try again ...");
try {
if (cdl.getCount() <= 0) {
cdl = new CountDownLatch(1);
}
cdl.await();
} catch (InterruptedException e1) {
e1.printStackTrace();
}
}
}
}
/**
* 释放分布式锁
*/
public boolean releaseLock(String path) {
try {
String keyPath = "/" + ROOT_PATH_LOCK + "/" + path;
if (curatorFramework.checkExists().forPath(keyPath) != null) {
curatorFramework.delete().forPath(keyPath);
}
} catch (Exception e) {
log.error("releaseLock|failed to release lock|path:{}", path, e);
return false;
}
return true;
}
/**
* 创建 watcher 事件
*/
private void addWatch(String path) throws Exception {
String keyPath;
if (path.equals(ROOT_PATH_LOCK)) {
keyPath = "/" + path;
} else {
keyPath = "/" + ROOT_PATH_LOCK + "/" + path;
}
final PathChildrenCache cache = new PathChildrenCache(curatorFramework, keyPath, false);
cache.start(PathChildrenCache.StartMode.POST_INITIALIZED_EVENT);
cache.getListenable().addListener((client, event) -> {
if (event.getType().equals(PathChildrenCacheEvent.Type.CHILD_REMOVED)) {
String oldPath = event.getData().getPath();
log.info("addWatch|success to release lock for path:{}", oldPath);
if (oldPath.contains(path)) {
//释放计数器，让当前的请求获取锁
cdl.countDown();
}
}
});
}
//创建父节点，并创建永久节点
@Override
public void afterPropertiesSet() throws Exception {
curatorFramework = curatorFramework.usingNamespace("lock-namespace");
String path = "/" + ROOT_PATH_LOCK;
try {
if (curatorFramework.checkExists().forPath(path) == null) {
curatorFramework.create()
.creatingParentsIfNeeded()
.withMode(CreateMode.PERSISTENT)
.withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
.forPath(path);
}
addWatch(ROOT_PATH_LOCK);
log.info("root path 的 watcher 事件创建成功");
} catch (Exception e) {
log.error("connect zookeeper fail,please check the log >> {}", e.getMessage(), e);
}
}
}
测试代码
// docker exec -it zk /bin/bash 进入zk容器
// 在bin下执行 zkCli.sh 进入zk终端
// 执行 ls /name-space/rootlock,将看到下面有没有加锁的目录,能看到锁释放的时候下面的目录会被删除
@Autowired
private DistributedLockByCurator distributedLockByCurator;
@Test
public void getZkLock() throws Exception{
distributedLockByCurator.acquireLock("test1");
Thread.sleep(60000);
boolean result = distributedLockByCurator.releaseLock("test1");
System.out.println("释放锁1的结果 = " + result);
distributedLockByCurator.acquireLock("lock2");
Thread.sleep(60000);
boolean result2 = distributedLockByCurator.releaseLock("lock2");
System.out.println("释放锁2的结果 = " + result2);
}
