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本文主要研究一下PowerJob的UseCacheLock

UseCacheLock

tech/powerjob/server/core/lock/UseCacheLock.java

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface UseCacheLock {

    String type();

    String key();

    int concurrencyLevel();
}

UseCacheLock注解定义了type、key、concurrencyLevel属性

UseCacheLockAspect

tech/powerjob/server/core/lock/UseCacheLockAspect.java

@Slf4j
@Aspect
@Component
@Order(1)
@RequiredArgsConstructor
public class UseCacheLockAspect {

    private final MonitorService monitorService;

    private final Map<String, Cache<String, ReentrantLock>> lockContainer = Maps.newConcurrentMap();

    private static final long SLOW_THRESHOLD = 100;

    @Around(value = "@annotation(useCacheLock))")
    public Object execute(ProceedingJoinPoint point, UseCacheLock useCacheLock) throws Throwable {
        Cache<String, ReentrantLock> lockCache = lockContainer.computeIfAbsent(useCacheLock.type(), ignore -> {
            int concurrencyLevel = useCacheLock.concurrencyLevel();
            log.info("[UseSegmentLockAspect] create Lock Cache for [{}] with concurrencyLevel: {}", useCacheLock.type(), concurrencyLevel);
            return CacheBuilder.newBuilder()
                    .initialCapacity(300000)
                    .maximumSize(500000)
                    .concurrencyLevel(concurrencyLevel)
                    .expireAfterWrite(30, TimeUnit.MINUTES)
                    .build();
        });
        final Method method = AOPUtils.parseMethod(point);
        Long key = AOPUtils.parseSpEl(method, point.getArgs(), useCacheLock.key(), Long.class, 1L);
        final ReentrantLock reentrantLock = lockCache.get(String.valueOf(key), ReentrantLock::new);
        long start = System.currentTimeMillis();
        reentrantLock.lockInterruptibly();
        try {
            long timeCost = System.currentTimeMillis() - start;
            if (timeCost > SLOW_THRESHOLD) {

                final SlowLockEvent slowLockEvent = new SlowLockEvent()
                        .setType(SlowLockEvent.Type.LOCAL)
                        .setLockType(useCacheLock.type())
                        .setLockKey(String.valueOf(key))
                        .setCallerService(method.getDeclaringClass().getSimpleName())
                        .setCallerMethod(method.getName())
                        .setCost(timeCost);

                monitorService.monitor(slowLockEvent);

                log.warn("[UseSegmentLockAspect] wait lock for method({}#{}) cost {} ms! key = '{}', args = {}, ", method.getDeclaringClass().getSimpleName(), method.getName(), timeCost,
                        key,
                        JSON.toJSONString(point.getArgs()));
            }
            return point.proceed();
        } finally {
            reentrantLock.unlock();
        }
    }
}

UseCacheLockAspect拦截@UseCacheLock注解，它定义了lockContainer维护了useCacheLock.type()与Cache的关系；Cache采用的guava的Cache，其initialCapacity为300000，maximumSize为500000，expireAfterWrite为30分钟；Cache的key为lock key，value为ReentrantLock；其execute方法主要是先执行reentrantLock.lockInterruptibly()，然后执行point.proceed()，最后reentrantLock.unlock()；执行point.proceed()之前还判断了一下加锁耗时，若超过SLOW_THRESHOLD(100ms)则通过monitorService.monitor上报SlowLockEvent

示例

    @UseCacheLock(type = "processJobInstance", key = "#instanceId", concurrencyLevel = 1024)
    public void redispatchAsync(Long instanceId, int originStatus) {
        // 将状态重置为等待派发
        instanceInfoRepository.updateStatusAndGmtModifiedByInstanceIdAndOriginStatus(instanceId, originStatus, InstanceStatus.WAITING_DISPATCH.getV(), new Date());
    }

key支持SpEl

小结

PowerJob的UseCacheLock注解定义了type、key、concurrencyLevel属性；UseCacheLockAspect拦截@UseCacheLock注解，它定义了lockContainer维护了useCacheLock.type()与Cache的关系；而Cache的key为lock key，value为ReentrantLock，最后是通过reentrantLock.lockInterruptibly()加锁。