再谈 Spring Boot + Redis 实现分布式锁

/** * 线程池，每个 JVM 使用一个线程去维护 keyAliveTime，定时执行 runnable */private static final ScheduledExecutorService SCHEDULER =new ScheduledThreadPoolExecutor(1,new BasicThreadFactory.Builder().namingPattern("redisLock-schedule-pool").daemon(true).build());static {    SCHEDULER.scheduleAtFixedRate(() -> {        // do something to extend time    }, 0,  2, TimeUnit.SECONDS);}

public enum RedisLockTypeEnum {    /**     * 自定义 key 前缀     */    ONE("Business1", "Test1"),
    TWO("Business2", "Test2");    private String code;    private String desc;    RedisLockTypeEnum(String code, String desc) {        this.code = code;        this.desc = desc;    }    public String getCode() {        return code;    }    public String getDesc() {        return desc;    }    public String getUniqueKey(String key) {        return String.format("%s:%s", this.getCode(), key);    }}

public class RedisLockDefinitionHolder {    /**     * 业务唯一 key     */    private String businessKey;    /**     * 加锁时间 (秒 s)     */    private Long lockTime;    /**     * 上次更新时间（ms）     */    private Long lastModifyTime;    /**     * 保存当前线程     */    private Thread currentTread;    /**     * 总共尝试次数     */    private int tryCount;    /**     * 当前尝试次数     */    private int currentCount;    /**     * 更新的时间周期（毫秒）,公式 = 加锁时间（转成毫秒） / 3     */    private Long modifyPeriod;    public RedisLockDefinitionHolder(String businessKey, Long lockTime, Long lastModifyTime, Thread currentTread, int tryCount) {        this.businessKey = businessKey;        this.lockTime = lockTime;        this.lastModifyTime = lastModifyTime;        this.currentTread = currentTread;        this.tryCount = tryCount;        this.modifyPeriod = lockTime * 1000 / 3;    }}

@Retention(RetentionPolicy.RUNTIME)@Target({ElementType.METHOD, ElementType.TYPE})public @interface RedisLockAnnotation {    /**     * 特定参数识别，默认取第 0 个下标     */    int lockFiled() default 0;    /**     * 超时重试次数     */    int tryCount() default 3;    /**     * 自定义加锁类型     */    RedisLockTypeEnum typeEnum();    /**     * 释放时间，秒 s 单位     */    long lockTime() default 30;}

/** * @annotation 中的路径表示拦截特定注解 */@Pointcut("@annotation(cn.sevenyuan.demo.aop.lock.RedisLockAnnotation)")public void redisLockPC() {}

@Around(value = "redisLockPC()")public Object around(ProceedingJoinPoint pjp) throws Throwable {    // 解析参数    Method method = resolveMethod(pjp);    RedisLockAnnotation annotation = method.getAnnotation(RedisLockAnnotation.class);    RedisLockTypeEnum typeEnum = annotation.typeEnum();    Object[] params = pjp.getArgs();    String ukString = params[annotation.lockFiled()].toString();    // 省略很多参数校验和判空    String businessKey = typeEnum.getUniqueKey(ukString);    String uniqueValue = UUID.randomUUID().toString();    // 加锁    Object result = null;    try {        boolean isSuccess = redisTemplate.opsForValue().setIfAbsent(businessKey, uniqueValue);        if (!isSuccess) {            throw new Exception("You can't do it，because another has get the lock =-=");        }        redisTemplate.expire(businessKey, annotation.lockTime(), TimeUnit.SECONDS);        Thread currentThread = Thread.currentThread();        // 将本次 Task 信息加入「延时」队列中        holderList.add(new RedisLockDefinitionHolder(businessKey, annotation.lockTime(), System.currentTimeMillis(),                currentThread, annotation.tryCount()));        // 执行业务操作        result = pjp.proceed();        // 线程被中断，抛出异常，中断此次请求        if (currentThread.isInterrupted()) {            throw new InterruptedException("You had been interrupted =-=");        }    } catch (InterruptedException e ) {        log.error("Interrupt exception, rollback transaction", e);        throw new Exception("Interrupt exception, please send request again");    } catch (Exception e) {        log.error("has some error, please check again", e);    } finally {        // 请求结束后，强制删掉 key，释放锁        redisTemplate.delete(businessKey);        log.info("release the lock, businessKey is [" + businessKey + "]");    }    return result;}

// 扫描的任务队列private static ConcurrentLinkedQueue<RedisLockDefinitionHolder> holderList = new ConcurrentLinkedQueue();/** * 线程池，维护keyAliveTime */private static final ScheduledExecutorService SCHEDULER = new ScheduledThreadPoolExecutor(1,        new BasicThreadFactory.Builder().namingPattern("redisLock-schedule-pool").daemon(true).build());{    // 两秒执行一次「续时」操作    SCHEDULER.scheduleAtFixedRate(() -> {        // 这里记得加 try-catch，否者报错后定时任务将不会再执行=-=        Iterator<RedisLockDefinitionHolder> iterator = holderList.iterator();        while (iterator.hasNext()) {            RedisLockDefinitionHolder holder = iterator.next();            // 判空            if (holder == null) {                iterator.remove();                continue;            }            // 判断 key 是否还有效，无效的话进行移除            if (redisTemplate.opsForValue().get(holder.getBusinessKey()) == null) {                iterator.remove();                continue;            }            // 超时重试次数，超过时给线程设定中断            if (holder.getCurrentCount() > holder.getTryCount()) {                holder.getCurrentTread().interrupt();                iterator.remove();                continue;            }            // 判断是否进入最后三分之一时间            long curTime = System.currentTimeMillis();            boolean shouldExtend = (holder.getLastModifyTime() + holder.getModifyPeriod()) <= curTime;            if (shouldExtend) {                holder.setLastModifyTime(curTime);                redisTemplate.expire(holder.getBusinessKey(), holder.getLockTime(), TimeUnit.SECONDS);                log.info("businessKey : [" + holder.getBusinessKey() + "], try count : " + holder.getCurrentCount());                holder.setCurrentCount(holder.getCurrentCount() + 1);            }        }    }, 0, 2, TimeUnit.SECONDS);}

@GetMapping("/testRedisLock")@RedisLockAnnotation(typeEnum = RedisLockTypeEnum.ONE, lockTime = 3)public Book testRedisLock(@RequestParam("userId") Long userId) {    try {        log.info("睡眠执行前");        Thread.sleep(10000);        log.info("睡眠执行后");    } catch (Exception e) {        // log error        log.info("has some error", e);    }    return null;}

2020-04-04 14:55:50.864  INFO 9326 --- [nio-8081-exec-1] c.s.demo.controller.BookController       : 睡眠执行前2020-04-04 14:55:52.855  INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect        : businessKey : [Business1:1024], try count : 02020-04-04 14:55:54.851  INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect        : businessKey : [Business1:1024], try count : 12020-04-04 14:55:56.851  INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect        : businessKey : [Business1:1024], try count : 22020-04-04 14:55:58.852  INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect        : businessKey : [Business1:1024], try count : 32020-04-04 14:56:00.857  INFO 9326 --- [nio-8081-exec-1] c.s.demo.controller.BookController       : has some errorjava.lang.InterruptedException: sleep interrupted at java.lang.Thread.sleep(Native Method) [na:1.8.0_221]