limiter

Limiter

Motivation

Limiter is designed to facilitate working with rate-limited APIs. It impl a token bucket that will allow a maximum number of function calls within a given interval.

Install

go get github.com/njayp/limiter

Examples

As a basic example, let's send 1000 requests at 200 requests per minute.

l := limiter.NewLimiter(200, time.Minute, 100*time.Millisecond)

for range 1000 {
	go func() {
		// wait for turn
		err := l.Wait(ctx)
		if err != nil {
			// handle error
			return
		}

		// send request
		err = do(ctx)
		if err != nil {
			// handle error
		}
	}()
}

As a more useful example, let's wrap a client and limiter into a limited client. LimitedClient.Do can be used thread-safely to send however many requests are desired without worrying about exceeding the rate limit.

type LimitedClient struct {
	limiter *limiter.Limiter
	client  *Client
}

func NewLimitedClient(limit int, interval time.Duration) *LimitedClient {
	return &LimitedClient{
		limiter: limiter.NewLimiter(limit, interval, 100*time.Millisecond),
		client:  NewClient(),
	}
}

func (lc *LimitedClient) Do(ctx context.Context, req *Request) (*Response, error) {
	err := lc.limiter.Wait(ctx)
	if err != nil {
		return nil, err
	}
	return lc.client.Do(ctx, req)
}