| package com.cnblogs.yjmyzz.redisdistributionlock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.util.StringUtils;
import java.util.UUID;
import java.util.concurrent.TimeUnit;
/**
* 利用redis获取分布式锁
*
* @author 菩提树下的杨过
* @blog http://yjmyzz.cnblogs.com/
*/
public class RedisLock {
private StringRedisTemplate redisTemplate;
private Logger logger = LoggerFactory.getLogger(this.getClass());
/**
* simple lock尝试获取锅的次数
*/
private int retryCount = 3;
/**
* 每次尝试获取锁的重试间隔毫秒数
*/
private int waitIntervalInMS = 100;
public RedisLock(StringRedisTemplate redisTemplate) {
this.redisTemplate = redisTemplate;
}
/**
* 利用redis获取分布式锁(未获取锁的请求，允许丢弃!)
*
* @param redisKey 锁的key值
* @param expireInSecond 锁的自动释放时间(秒)
* @return
* @throws DistributionLockException
*/
public String simpleLock(final String redisKey, final int expireInSecond) throws DistributionLockException {
String lockValue = UUID.randomUUID().toString();
boolean flag = false;
if (StringUtils.isEmpty(redisKey)) {
throw new DistributionLockException("key is empty!");
}
if (expireInSecond <= 0) {
throw new DistributionLockException("expireInSecond must be bigger than 0");
}
try {
for (int i = 0; i < retryCount; i++) {
boolean success = redisTemplate.opsForValue().setIfAbsent(redisKey, lockValue, expireInSecond, TimeUnit.SECONDS);
if (success) {
flag = true;
break;
}
try {
TimeUnit.MILLISECONDS.sleep(waitIntervalInMS);
} catch (Exception ignore) {
logger.warn("redis lock fail: " + ignore.getMessage());
}
}
if (!flag) {
throw new DistributionLockException(Thread.currentThread().getName() + " cannot acquire lock now ...");
}
return lockValue;
} catch (DistributionLockException be) {
throw be;
} catch (Exception e) {
logger.warn("get redis lock error, exception: " + e.getMessage());
throw e;
}
}
/**
* 利用redis获取分布式锁(未获取锁的请求，将在timeoutSecond时间范围内，一直等待重试)
*
* @param redisKey 锁的key值
* @param expireInSecond 锁的自动释放时间(秒)
* @param timeoutSecond 未获取到锁的请求，尝试重试的最久等待时间(秒)
* @return
* @throws DistributionLockException
*/
public String lock(final String redisKey, final int expireInSecond, final int timeoutSecond) throws DistributionLockException {
String lockValue = UUID.randomUUID().toString();
boolean flag = false;
if (StringUtils.isEmpty(redisKey)) {
throw new DistributionLockException("key is empty!");
}
if (expireInSecond <= 0) {
throw new DistributionLockException("expireInSecond must be greater than 0");
}
if (timeoutSecond <= 0) {
throw new DistributionLockException("timeoutSecond must be greater than 0");
}
if (timeoutSecond >= expireInSecond) {
throw new DistributionLockException("timeoutSecond must be less than expireInSecond");
}
try {
long timeoutAt = System.currentTimeMillis() + timeoutSecond * 1000;
while (true) {
boolean success = redisTemplate.opsForValue().setIfAbsent(redisKey, lockValue, expireInSecond, TimeUnit.SECONDS);
if (success) {
flag = true;
break;
}
if (System.currentTimeMillis() >= timeoutAt) {
break;
}
try {
TimeUnit.MILLISECONDS.sleep(waitIntervalInMS);
} catch (Exception ignore) {
logger.warn("redis lock fail: " + ignore.getMessage());
}
}
if (!flag) {
throw new DistributionLockException(Thread.currentThread().getName() + " cannot acquire lock now ...");
}
return lockValue;
} catch (DistributionLockException be) {
throw be;
} catch (Exception e) {
logger.warn("get redis lock error, exception: " + e.getMessage());
throw e;
}
}
/**
* 锁释放
*
* @param redisKey
* @param lockValue
*/
public void unlock(final String redisKey, final String lockValue) {
if (StringUtils.isEmpty(redisKey)) {
return;
}
if (StringUtils.isEmpty(lockValue)) {
return;
}
try {
String currLockVal = redisTemplate.opsForValue().get(redisKey);
if (currLockVal != null && currLockVal.equals(lockValue)) {
boolean result = redisTemplate.delete(redisKey);
if (!result) {
logger.warn(Thread.currentThread().getName() + " unlock redis lock fail");
} else {
logger.info(Thread.currentThread().getName() + " unlock redis lock:" + redisKey + " successfully!");
}
}
} catch (Exception je) {
logger.warn(Thread.currentThread().getName() + " unlock redis lock error:" + je.getMessage());
}
}
}
|
