var limit struct {
	count int
	cycle time.Duration
}

func init() {
	limit.count = 2
	limit.cycle = 3 * time.Second
}

func ratelimit() func(c *gin.Context) {
	return func(c *gin.Context) {

		// 獲取客戶端IP
		clientIP := c.ClientIP()
		// 不包括參數(shù)
		path := c.Request.URL.Path
		key := clientIP + path
        
		valStr, err := rdb.Get(c, key).Result()
		if err != nil {
			// 根據(jù)業(yè)務處理(放行/攔截)
		}
		val, _ := strconv.Atoi(valStr)
		if val >= limit.count {
			c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{
				"code": 1,
				"msg":  "請求過于頻繁",
			})
			return
		}
		count, err := rdb.Incr(context.Background(), key).Result()
		if err != nil {
			// 根據(jù)業(yè)務處理(放行/攔截)
		}
		if count == 1 {
			err = rdb.Expire(context.Background(), key, limit.cycle).Err()
			if err != nil {
				// 刪除key或者重試
			}
		}
		if int(count) > limit.count {
			c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{
				"code": 1,
				"msg":  "請求過于頻繁",
			})
			return
		}
	}
}

var limit struct {
	count int64
	cycle int64 // 單位s
}

func init() {
	limit.count = 2
	limit.cycle = 3
}

func ratelimit() func(c *gin.Context) {
	return func(c *gin.Context) {

		clientIp := c.ClientIP()
		path := c.Request.URL.Path
		key := clientIp + path

		t := time.Now().Unix()
		has, _ := rdb.Exists(context.Background(), key).Result()
		count, _ := rdb.ZCount(context.Background(), key, fmt.Sprintf("%d", t-limit.cycle), "+inf").Result()
		if has == 0 { // 如果是第一次創(chuàng)建，最長時間不超過1小時
			rdb.Expire(context.Background(), key, 1*time.Hour) // 從功能上來說，此處不管是否設置成功，都不影響限流功能
		}
		if count >= limit.count { // 超出次數(shù)，限制
			c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{
				"code": 1,
				"msg":  "請求過于頻繁",
			})
			return
		}
		
		rdb.ZAdd(context.Background(), key, &redis.Z{Score: float64(t), Member: strconv.Itoa(int(t))})
		// 刪除窗口外的數(shù)據(jù)
		go func() {
			memberToRemove, _ := rdb.ZRangeByScore(context.Background(), key, &redis.ZRangeBy{
				Max: strconv.Itoa(int(t - limit.cycle)),
				Min: "0",
			}).Result()
			if len(memberToRemove) > 0 {
				rdb.ZRem(context.Background(), key, memberToRemove)
			}
		}()
	}
}

import (
	"fmt"
	"time"

	"go.uber.org/ratelimit"
)

func main() {
    rl := ratelimit.New(100) // 每秒多少次

    prev := time.Now()
    for i := 0; i < 10; i++ {
        now := rl.Take()	// 平均時間
        fmt.Println(i, now.Sub(prev))
        prev = now
    }

    // Output:
    // 0 0
    // 1 10ms
    // 2 10ms
    // 3 10ms
    // 4 10ms
    // 5 10ms
    // 6 10ms
    // 7 10ms
    // 8 10ms
    // 9 10ms
}

import (
	"github.com/gin-gonic/gin"
	"go.uber.org/ratelimit"
	"sync"
	"time"
)

var limiters sync.Map

func ratelimitMiddleware() func(c *gin.Context) {
	return func(c *gin.Context) {

		clientIp := c.ClientIP()
		path := c.Request.URL.Path
		key := clientIp + path

		var rl ratelimit.Limiter
		if limiterVal, ok := limiters.Load(key); ok {
			rl = limiterVal.(ratelimit.Limiter)
		} else {
			newLimiter := ratelimit.New(1)	// 每秒只能請求1次
			limiters.Store(key, newLimiter)
			rl = newLimiter
			go func(string) { // 簡易回收key，防止limiters 無限增大
				time.Sleep(1 * time.Hour)
				limiters.Delete(key)
			}(key)
		}

		rl.Take() // 超過請求次數(shù)會進行阻塞，直到放行或放棄請求

	}
}

limiter := rate.NewLimiter(10, 2)

func (lim *Limiter) Wait(ctx context.Context) (err error)
func (lim *Limiter) WaitN(ctx context.Context, n int) (err error)

func (lim *Limiter) Allow() bool
func (lim *Limiter) AllowN(now time.Time, n int) bool 

func (lim *Limiter) Reserve() *Reservation
func (lim *Limiter) ReserveN(now time.Time, n int) *Reservation

func ratelimitMiddleware() func(gin.Context) {
	return func(c gin.Context) {

		client := c.ClientIP()
		path := c.Request.URL.Path
		key := client + path

		var rl *rate.Limiter
		if limitersVal, ok := limiters.Load(key); ok {
			rl = limitersVal.(*rate.Limiter)
		} else {
			newLimiter := rate.NewLimiter(1, 10)
			limiters.Store(key, newLimiter)
			rl = newLimiter
			go func(string2 string) {
				time.Sleep(1 * time.Second)
				limiters.Delete(key)
			}(key)
		}
		if !rl.Allow() {
			c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{
				"code": 1,
				"msg":  "請求過于頻繁",
			})
		}
	}
}