在此之前，去看了下Redission的实现原理，不过在开发中，原本的代码使用RedistTemplate实现的，也不太想换，所以我想了下，不如自己实现要给WatchDog。
我的想法是，在用户加上锁的时候开启个定时任务线程，并且在定时任务中，判断原线程isAlive状态进行“续命”。
下面是代码(在这里面为了方便，未使用的是HuTool.CornUtil来实现动态定时任务)：
代码语言：javascript复制/**
* Title
*
* @ClassName: LockUtil
* @Description:锁工具类,通过内部枚举类实现单例，防止反射攻击
* @author: Karos
* @date: 2023/1/4 0:17
* @Blog: https://www.wzl1.top/
*/
package cn.katool.lock;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.ObjectUtil;
import cn.hutool.cron.CronUtil;
import cn.hutool.cron.task.Task;
import cn.katool.Config.LockConfig;
import cn.katool.Exception.ErrorCode;
import cn.katool.Exception.KaToolException;
import cn.katool.other.MethodIntefaceUtil;
import com.qiniu.util.StringUtils;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Scope;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import org.springframework.util.ObjectUtils;
import javax.annotation.Resource;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
@Component
@Scope("prototype")
@Slf4j
public class LockUtil {
@Resource
RedisTemplate redisTemplate;
private LockUtil(){
}
private static boolean isOpenCorn=false;
/**
* 带看门狗机制上锁
* @param lockObj
* @return
*/
public boolean DistributedLock(Object lockObj){
try {
return DistributedLock(lockObj,null,null);
} catch (KaToolException e) {
throw new RuntimeException(e);
}
}
@Resource
LockConfig lockConfig;
//加锁
/**
* 无看门狗机制上锁
* @param obj
* @param exptime
* @param timeUnit
* @return
* @throws KaToolException
*/
public boolean DistributedLock(Object obj,Long exptime,TimeUnit timeUnit) throws KaToolException {
if (ObjectUtil.isEmpty(obj)){
throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空");
}
Boolean isDelay=false;
if (ObjectUtil.isAllEmpty(exptime,timeUnit)){
isDelay=true;
}
if(ObjectUtil.isEmpty(exptime)){
exptime= lockConfig.getInternalLockLeaseTime();;
}
if (ObjectUtils.isEmpty(timeUnit)){
timeUnit=lockConfig.getTimeUnit();
}
//线程被锁住了，就一直等待
DistributedAssert(obj);
Boolean aBoolean = redisTemplate.opsForValue().setIfAbsent("Lock:" obj.toString(), "1", exptime, timeUnit);
log.info("katool=> LockUntil => DistributedLock:{} value:{} extime:{} timeUnit:{}",obj.toString(), "1", exptime, timeUnit);
//实现看门狗
if (isDelay){
if (LockUtil.isOpenCorn==false){
//如果同一个项目之前打开过，那么先关闭，避免重复启动
CronUtil.stop();
//支持秒级别定时任务
CronUtil.setMatchSecond(true);
//定时服务启动
CronUtil.start();
LockUtil.isOpenCorn=true;
}
Thread thread = Thread.currentThread();
TimeUnit finalTimeUnit = timeUnit;
Long finalExptime = exptime;
class TempClass{
public String scheduleId;
}
final TempClass tempClass = new TempClass();
tempClass.scheduleId=CronUtil.schedule("0/30 * * * * ?", new Task() {
@SneakyThrows
@Override
public void execute() {
boolean alive = thread.isAlive();
if (alive) {
delayDistributedLock(obj, finalExptime>=3?(finalExptime / 3):finalExptime, finalTimeUnit);
return;
} else {
if (tempClass.scheduleId==null||"".equals(tempClass.scheduleId)){
return;
}
CronUtil.remove(tempClass.scheduleId);
DistributedUnLock(obj);
return;
}
}
});
}
return BooleanUtil.isTrue(aBoolean);
}
//检锁
public void DistributedAssert(Object obj) throws KaToolException {
if (ObjectUtils.isEmpty(obj)){
throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空");
}
while(true){
Object o = redisTemplate.opsForValue().get("Lock:" obj.toString());
if (ObjectUtils.isEmpty(o))return;
}
}
//延期
public boolean delayDistributedLock(Object obj,Long exptime,TimeUnit timeUnit) throws KaToolException {
if (ObjectUtils.isEmpty(obj)){
throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空");
}
Boolean aBoolean = redisTemplate.opsForValue().setIfPresent("Lock:" obj.toString(), "1", exptime, timeUnit);
log.info("katool=> LockUntil => delayDistributedLock:{} value:{} extime:{} timeUnit:{}",obj.toString(), "1", exptime, timeUnit);
return BooleanUtil.isTrue(aBoolean);
}
//释放锁
public boolean DistributedUnLock(Object obj) throws KaToolException {
if (ObjectUtils.isEmpty(obj)){
throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空");
}
Boolean aBoolean = redisTemplate.delete("Lock:" obj.toString());
log.info("katool=> LockUntil => unDistributedLock:{} isdelete:{} ",obj.toString(),true);
return BooleanUtil.isTrue(aBoolean);
}
//利用枚举类实现单例模式，枚举类属性为静态的
private enum SingletonFactory{
Singleton;
LockUtil lockUtil;
private SingletonFactory(){
lockUtil=new LockUtil();
}
public LockUtil getInstance(){
return lockUtil;
}
}
@Bean("LockUtil")
public static LockUtil getInstance(){
return SingletonFactory.Singleton.lockUtil;
}
}
