ratelimiter

Go universal rate limiter with easy to use API.

Package provides methods to rate limit any type of requests (not only http). Use builtin Bottlenecks or write your own for custom bottle neck logic.

Compares to most popular solutions

go.uber.org/ratelimit

• go.uber.org/ratelimit does not support burst option
• go.uber.org/ratelimit cannot cancel request or shrink queue

x/time/rate

• x/time/rate cannot cancel request or shrink queue

github.com/reugn/equalizer

• github.com/reugn/equalizer does not support burst option

Benchmarks

Overhead of each Take()/Wait() request with infinity rate:

$ # RegularBottleneck lies on memory usage because uses slice of int64 with length of required RPS
$ go test -bench=. -benchmem -benchtime=10000000x
warning: GOPATH set to GOROOT (/home/user/go) has no effect
goos: linux
goarch: amd64
pkg: github.com/alexdyukov/ratelimiter/v2
cpu: AMD Ryzen 7 8845H w/ Radeon 780M Graphics
BenchmarkRegularBottleneck-16           10000000               228.6 ns/op             0 B/op          0 allocs/op
BenchmarkValveBottleneck-16             10000000               163.0 ns/op             0 B/op          0 allocs/op
BenchmarkEqualizerBottleneck-16         10000000               229.3 ns/op             0 B/op          0 allocs/op
PASS
ok      github.com/alexdyukov/ratelimiter/v2    11.662s

Example

package main

import (
        "io/ioutil"
        "net/http"

        "github.com/alexdyukov/ratelimiter/v2"
        "github.com/alexdyukov/ratelimiter/v2/bottleneck"
)

func main() {
        rps := 100
        burst := 25

        bn := bottleneck.NewRegular(rps, burst)
        rl := ratelimiter.New(bn)

        echo := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
                if !rl.Take(r.Context()) {
                        w.Header().Add("Retry-After", "60")
                        http.Error(w, "Try again later", http.StatusServiceUnavailable)
                        return
                }
                data, _ := ioutil.ReadAll(r.Body)
                w.Write(data)
        })

        http.ListenAndServe(":8080", echo)
}

License

MIT licensed. See the included LICENSE file for details.