[請(qǐng)求入口] → [指紋生成器] → [防抖決策引擎] 
                   ↓              ↑
                [Redis集群] ← [動(dòng)態(tài)規(guī)則配置中心]

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Debounce {
    // 冷卻時(shí)間（動(dòng)態(tài)基準(zhǔn)值）
    long baseTime() default 3000;
    // 最大冷卻時(shí)間
    long maxTime() default 10000;
    // 時(shí)間單位
    TimeUnit unit() default TimeUnit.MILLISECONDS;
    // 防抖維度（用戶/設(shè)備/全局）
    ScopeType scope() default ScopeType.USER;
}


public enum ScopeType {
    GLOBAL, USER, DEVICE
}

public class RequestFingerprintGenerator {
    private static final Hashing MURMUR3 = Hashing.murmur3_128();


    public String generate(HttpServletRequest request, Object[] args) {
        String paramHash = Arrays.stream(args)
                .map(JacksonUtil::toJson)
                .collect(Collectors.joining());


        String userInfo = Optional.ofNullable(SecurityContextHolder.getContext())
                .map(SecurityContext::getAuthentication)
                .map(Authentication::getName)
                .orElse("ANONYMOUS");


        String deviceId = request.getHeader("X-Device-ID");


        return MURMUR3.hashUnencodedChars(
            paramHash + userInfo + deviceId
        ).toString();
    }
}

@Aspect
@Component
@Slf4j
public class DebounceAspect {
    private final RedissonClient redisson;
    private final Cache<String, Long> localCache;


    @Around("@annotation(debounce)")
    public Object around(ProceedingJoinPoint pjp, Debounce debounce) throws Throwable {
        String fingerprint = generateFingerprint(pjp);
        Long lastTime = getLastRequestTime(fingerprint);


        long waitTime = calculateWaitTime(lastTime, debounce);
        if (waitTime > 0) {
            throw new DebounceException("請(qǐng)求過于頻繁，請(qǐng)"+waitTime+"ms后重試");
        }


        updateRequestTime(fingerprint, debounce);
        return pjp.proceed();
    }


    private long calculateWaitTime(Long lastTime, Debounce debounce) {
        if (lastTime == null) return 0;


        long elapsed = System.currentTimeMillis() - lastTime;
        long base = debounce.unit().toMillis(debounce.baseTime());
        long max = debounce.unit().toMillis(debounce.maxTime());


        // 動(dòng)態(tài)冷卻算法：指數(shù)退避
        long coolTime = Math.min(base * (1 << retryCount), max);
        return coolTime - elapsed;
    }


    private void updateRequestTime(String key, Debounce debounce) {
        RLock lock = redisson.getLock(key);
        try {
            lock.lock();
            long expire = debounce.unit().toMillis(debounce.maxTime());
            redisTemplate.opsForValue().set(key, System.currentTimeMillis(), expire);
            localCache.put(key, System.currentTimeMillis());
        } finally {
            lock.unlock();
        }
    }
}

// Caffeine本地緩存配置
@Bean
public Cache<String, Long> localDebounceCache() {
    return Caffeine.newBuilder()
            .maximumSize(10_000)
            .expireAfterWrite(1, TimeUnit.MINUTES)
            .build();
}


// 防抖查詢優(yōu)化
private Long getLastRequestTime(String key) {
    Long localTime = localCache.getIfPresent(key);
    if (localTime != null) {
        return localTime;
    }
    return (Long) redisTemplate.opsForValue().get(key);
}

// 基于QPS的冷卻時(shí)間動(dòng)態(tài)調(diào)整
private void adjustCoolTime(String key) {
    RateLimiter limiter = RateLimiter.create(10); // 初始10 QPS
    while (true) {
        double qps = limiter.getRate();
        long newCoolTime = (long)(1000 / qps);
        updateCoolTimeConfig(key, newCoolTime);
        Thread.sleep(5000);
    }
}

// 解決熱點(diǎn)Key問題
private String getStorageKey(String fingerprint) {
    int shard = Hashing.consistentHash(
        Hashing.sha256().hashString(fingerprint), 
        SHARD_COUNT
    );
    return "debounce:shard_" + shard + ":" + fingerprint;
}

resilience4j:
  circuitbreaker:
    instances:
      debounce:
        failureRateThreshold: 50
        minimumNumberOfCalls: 10
        automaticTransitionFromOpenToHalfOpenEnabled: true