Golang微服务如何设计API限流方案 实现令牌桶与漏桶算法

type TokenBucket struct {
    capacity  int64 // 桶的最大容量
    tokens    int64 // 当前令牌数
    rate      int64 // 每秒添加多少个令牌
    lastTime  time.Time
    mu        sync.Mutex
}

func (tb *TokenBucket) Allow() bool {
    tb.mu.Lock()
    defer tb.mu.Unlock()

    now := time.Now()
    elapsed := now.Sub(tb.lastTime).Seconds()
    tb.lastTime = now

    newTokens := int64(elapsed * float64(tb.rate))
    tb.tokens += newTokens
    if tb.tokens > tb.capacity {
        tb.tokens = tb.capacity
    }

    if tb.tokens < 1 {
        return false
    }

    tb.tokens--
    return true
}

type LeakyBucket struct {
    capacity   int       // 桶的总容量
    water      int       // 当前水量
    rate       int       // 每秒排水量
    lastLeakAt time.Time
    mu         sync.Mutex
}

func (lb *LeakyBucket) Allow() bool {
    lb.mu.Lock()
    defer lb.mu.Unlock()

    now := time.Now()
    diff := now.Sub(lb.lastLeakAt).Seconds()
    lb.lastLeakAt = now

    lb.water = max(0, lb.water - int(diff)*lb.rate)

    if lb.water+1 > lb.capacity {
        return false
    }

    lb.water++
    return true
}

func RateLimitMiddleware(bucket *TokenBucket) gin.HandlerFunc {
    return func(c *gin.Context) {
        if !bucket.Allow() {
            c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{"error": "rate limit exceeded"})
            return
        }
        c.Next()
    }
}