ratelimit an operation based on id tokens
Package ratelimiter enables rate limiting of operations based on id tokens
$ go get github.com/m90/go-ratelimiterCreate a new Limiter instance using New(limit time.Duration, cache GetSetter) Throttler:
limiter := ratelimiter.New(time.Second, cache)
for {
// this will only run every second
<-limiter.Throttle("never ending for loop")
fmt.Println("one second has passed")
}The passed cache needs to implement GetSetter:
type GetSetter interface {
Get(key string) (interface{}, bool)
Set(key string, value interface{}, expiry time.Duration)
}go-cache works out of the box.
Each call to Throttle(id string) <-chan Result returns information on the resulting delay or possible errors:
limiter := ratelimiter.New(time.Second, cache)
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
id := r.URL.Query().Get("id")
throttling := <-limiter.Throttle(id)
if throttling.Error != nil {
fmt.Println("Error rate limiting")
}
if throttling.Delay > 0 {
fmt.Printf("Delayed next request for %s by %s\n", id, throttling.Delay.String())
}
})If you want to fulfill Throttler without any rate limiting taking place, you can use NewNoopRateLimiter() Throttler:
limiter := ratelimiter.NewNoopRateLimiter()
for {
// this will only run every second
<-limiter.Throttle("never ending for loop")
fmt.Println("this will run without any interruption")
}MIT © Frederik Ring