5.切点前进行加锁,任务执行后进行删除 key
/** * 堆代码 duidaima.com * 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); }三. 设计方案
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); } }任务队列保存参数
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 */ privateint tryCount; /** * 当前尝试次数 */ privateint 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; } }设定被拦截的注解名字
@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; }核心切面拦截的操作
/** * @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 前后进行加锁和释放锁
@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) { thrownew 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()) { thrownew InterruptedException("You had been interrupted =-="); } } catch (InterruptedException e ) { log.error("Interrupt exception, rollback transaction", e); thrownew 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; }上述流程简单总结一下:
// 扫描的任务队列 privatestatic ConcurrentLinkedQueue<RedisLockDefinitionHolder> holderList = new ConcurrentLinkedQueue(); /** * 线程池,维护keyAliveTime */ privatestaticfinal 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); }这段代码,用来实现设计图中虚线框的思想,避免一个请求十分耗时,导致提前释放了锁。这里加了「线程中断」Thread#interrupt,希望超过重试次数后,能让线程中断(未经严谨测试,仅供参考哈哈哈哈)。不过建议如果遇到这么耗时的请求,还是能够从根源上查找,分析耗时路径,进行业务优化或其它处理,避免这些耗时操作。所以记得多打点 Log,分析问题时可以更快一点。记录项目日志,一个注解搞定。
@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; }使用时,在方法上添加该注解,然后设定相应参数即可,根据 typeEnum 可以区分多种业务,限制该业务被同时操作。
2025-01-04 14:55:50.864 INFO 9326 --- [nio-8081-exec-1] c.s.demo.controller.BookController : 睡眠执行前 2025-01-04 14:55:52.855 INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect : businessKey : [Business1:1024], try count : 0 2025-01-04 14:55:54.851 INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect : businessKey : [Business1:1024], try count : 1 2025-01-04 14:55:56.851 INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect : businessKey : [Business1:1024], try count : 2 2025-01-04 14:55:58.852 INFO 9326 --- [k-schedule-pool] c.s.demo.aop.lock.RedisLockAspect : businessKey : [Business1:1024], try count : 3 2025-01-04 14:56:00.857 INFO 9326 --- [nio-8081-exec-1] c.s.demo.controller.BookController : has some error java.lang.InterruptedException: sleep interrupted at java.lang.Thread.sleep(Native Method) [na:1.8.0_221]我这里测试的是重试次数过多,失败的场景,如果减少睡眠时间,就能让业务正常执行。如果同时请求,你将会发现以下错误信息: