Go 限流落地：从 x/time/rate 单机令牌桶到 Redis 分布式限流演进与性能实测

package main

import (
	"context"
	"fmt"
	"time"

	"golang.org/x/time/rate"
)

func main() {
	// 每秒生成 10 个令牌，桶容量为 20（允许突发 20 QPS）
	limiter := rate.NewLimiter(rate.Limit(10), 20)

	ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
	defer cancel()

	// 1. 阻塞等待：适合消息消费
	if err := limiter.Wait(ctx); err != nil {
		fmt.Println("Wait 超时或被取消:", err)
	}

	// 2. 非阻塞判断：适合 HTTP 接口直接拒绝 (429 Too Many Requests)
	if limiter.Allow() {
		fmt.Println("放行请求")
	} else {
		fmt.Println("触发限流")
	}
}

goos: darwin
goarch: arm64
pkg: demo/ratelimit
BenchmarkRateLimiter_Allow-8         13842159        86.42 ns/op        0 B/op        0 allocs/op
BenchmarkUberRateLimit_Take-8        24183742        49.31 ns/op        0 B/op        0 allocs/op

local key = KEYS[1]
local now = tonumber(ARGV[1])
local window = tonumber(ARGV[2])
local limit = tonumber(ARGV[3])

-- 清理窗口外的过期数据
redis.call('ZREMRANGEBYSCORE', key, '-inf', now - window)

-- 获取当前窗口内的请求数
local current_requests = redis.call('ZCARD', key)

if current_requests < limit then
    -- 写入当前请求的时间戳作为 score 和 member
    redis.call('ZADD', key, now, now)
    -- 设置 key 过期时间，防止冷数据常驻
    redis.call('EXPIRE', key, math.ceil(window / 1000))
    return 1
else
    return 0
end

package main

import (
	"context"
	"fmt"
	"time"

	"github.com/redis/go-redis/v9"
)

var slidingWindowLua = redis.NewScript(`
local key = KEYS[1]
local now = tonumber(ARGV[1])
local window = tonumber(ARGV[2])
local limit = tonumber(ARGV[3])

redis.call('ZREMRANGEBYSCORE', key, '-inf', now - window)
local current = redis.call('ZCARD', key)

if current < limit then
    redis.call('ZADD', key, now, now)
    redis.call('EXPIRE', key, math.ceil(window / 1000))
    return 1
else
    return 0
end
`)

type RedisLimiter struct {
	client *redis.Client
}

func (r *RedisLimiter) Allow(ctx context.Context, key string, window time.Duration, limit int64) (bool, error) {
	now := time.Now().UnixMilli()
	windowMs := window.Milliseconds()

	res, err := slidingWindowLua.Run(ctx, r.client, []string{key}, now, windowMs, limit).Result()
	if err != nil {
		return false, err
	}

	return res.(int64) == 1, nil
}