ratelimit

README

Distributed rate-limit library based on Redis

---

Overview

The goal of this library is to be able to implement distributed rate limit functions simply and rudely. Similar to the usage of the ID generator, the client takes back the data from Redis - batch data (just a value here), as long as it Is not consumed.it doesn't exceed rate-limit.

• 中文 README

Advantage

• Less dependencies, only rely on Redis, no special services required
• use Redis own clock, The clients no need to have the same clock
• Thread (coroutine) security
• Low system overhead and little pressure on redis

Notice

Different types of limiters may have different redis-key data types in redis. So different types of limiters cannot use same name redis-key.

For example

127.0.0.1:6379> type key:leaky
string
127.0.0.1:6379> type key:token
hash
127.0.0.1:6379> hgetall key:token

"token_count"
"0"
"updateTime"
"1613805726567122"
127.0.0.1:6379> get key:leaky
"1613807035353864"

How to get

go get github.com/vearne/ratelimit

Usage

1. create redis.Client

with "github.com/redis/go-redis"
Supports both redis master-slave mode and cluster mode

	client := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Password: "xxx", // no password set
		DB:       0,  // use default DB
	})

	client := redis.NewClusterClient(&redis.ClusterOptions{
		Addrs:    []string{"127.0.0.1:6379"},
		Password: "xxxx",
	})

2. create RateLimiter

limiter, err := ratelimit.NewTokenBucketRateLimiter(ctx, client,                
        "push", time.Second, 200, 20, 5)

Indicates that 200 operations per second are allowed.

	limiter, err := ratelimit.NewTokenBucketRateLimiter(client, 
	        ctx, "push", time.Minute, 200, 20, 5)

Indicates that 200 operations per minute are allowed.

2.1 Counter algorithm

func NewCounterRateLimiter(ctx context.Context, client redis.Cmdable, key string, duration time.Duration,
	throughput int,
	batchSize int) (Limiter, error)

parameter	Description
key	Key in Redis
duration	Indicates that the operation throughput is allowed in the duration time interval
throughput	Indicates that the operation throughput is allowed in the duration time interval
batchSize	The number of available operations each time retrieved from redis

2.2 Token bucket algorithm

func NewTokenBucketRateLimiter(ctx context.Context, client redis.Cmdable, key string, duration time.Duration,
	throughput int, maxCapacity int,
	batchSize int) (Limiter, error)

parameter	Description
key	Key in Redis
duration	Indicates that the operation throughput is allowed in the duration time interval
throughput	Indicates that the operation throughput is allowed in the duration time interval
maxCapacity	The maximum number of tokens that can be stored in the token bucket
batchSize	The number of available operations each time retrieved from redis

2.3 Leaky bucket algorithm

func NewLeakyBucketLimiter(ctx context.Context, client redis.Cmdable, key string, duration time.Duration,
	throughput int) (Limiter, error) 

parameter	Description
key	Key in Redis
duration	Indicates that the operation throughput is allowed in the duration time interval
throughput	Indicates that the operation throughput is allowed in the duration time interval

2.4 sliding time window

NewSlideTimeWindowLimiter(throught int, duration time.Duration, windowBuckets int) (Limiter, error)

parameter	Description
duration	Indicates that the operation throughput is allowed in the duration time interval
throughput	Indicates that the operation throughput is allowed in the duration time interval
windowBuckets	Indicates that windowBuckets buckets will be created for duration, and the time range represented by each bucket is duration/windowBuckets

Note: This limiter is based on memory and does not rely on Redis, so it may not be used in distributed frequency limiting scenarios.

example

more example

package main

import (
	"context"
	"fmt"
	"github.com/redis/go-redis/v9"
	"github.com/vearne/ratelimit"
	"github.com/vearne/ratelimit/counter"
	"github.com/vearne/ratelimit/tokenbucket"
	slog "github.com/vearne/simplelog"
	"sync"
	"time"
)

func consume(r ratelimit.Limiter, group *sync.WaitGroup,
	c *counter.Counter, targetCount int) {
	defer group.Done()
	var ok bool
	for {
		ok = true
		err := r.Wait(context.Background())
		slog.Debug("r.Wait:%v", err)
		if err != nil {
			ok = false
			slog.Error("error:%v", err)
		}
		if ok {
			value := c.Incr()
			slog.Debug("---value--:%v", value)
			if value >= targetCount {
				break
			}
		}
	}
}

func main() {
	client := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Password: "xxeQl*@nFE", // password set
		DB:       0,            // use default DB
	})

	limiter, err := tokenbucket.NewTokenBucketRateLimiter(
		context.Background(),
		client,
		"key:token",
		time.Second,
		10,
		5,
		2)

	if err != nil {
		fmt.Println("error", err)
		return
	}

	var wg sync.WaitGroup
	total := 50
	counter := counter.NewCounter()
	start := time.Now()
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go consume(limiter, &wg, counter, total)
	}
	wg.Wait()
	cost := time.Since(start)
	fmt.Println("cost", time.Since(start), "rate", float64(total)/cost.Seconds())
}

Dependency

redis/go-redis

Thanks

The development of the module was inspired by the Reference 1.

Reference

1. Performance million/s: Tencent lightweight global flow control program

Thanks

Documentation

Index

• Constants
• Variables
• type BaseRateLimiter
• type Limiter

Constants

const (
	TokenBucketAlg = iota
	CounterAlg
	LeakyBucketAlg
)

const LeakyBucketScript = `` /* 473-byte string literal not displayed */

	key Type:  string

    // updateTime
	key -> {lastUpdateTime}* 1000000  +  {microsecond}

const TokenBucketScript = `` /* 959-byte string literal not displayed */

Variables

var (
	AlgMap map[int]string
)

Types

type BaseRateLimiter

type BaseRateLimiter struct {
	sync.Mutex
	ScriptSHA1  string
	Key         string
	RedisClient redis.Cmdable
	// For interval between requests,the smallest unit of duration is one microseconds.
	Interval time.Duration
}

nolint: govet

type Limiter

type Limiter interface {
	Take(ctx context.Context) (bool, error)
	Wait(ctx context.Context) (err error)
}