全球聚焦：针对RedisTemplate分布式锁实现WatchDog

(资料图片仅供参考)

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)：

/** * 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")@Slf4jpublic 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;        }}

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