faucet: comments and refactor

cmd/faucet/faucet.go

@@ -238,7 +238,7 @@ func newFaucet(genesis *core.Genesis, url string, ks *keystore.KeyStore, index [
 		return nil, err
 	}
 
-	// Allow 1 request per minute with burst of 5, and cache up to 10000 IPs
+	// Allow 1 request per minute with burst of 5, and cache up to 1000 IPs
 	limiter, err := NewIPRateLimiter(rate.Limit(1.0), 5, 1000)
 	if err != nil {
 		return nil, err
@@ -290,8 +290,7 @@ func (f *faucet) apiHandler(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	limiter := f.limiter.GetLimiter(ip)
-	if !limiter.Allow() {
+	if !f.limiter.GetLimiter(ip).Allow() {
 		log.Warn("Too many requests from client: ", "client", ip)
 		http.Error(w, "Too many requests", http.StatusTooManyRequests)
 		return

cmd/faucet/rate_limiter.go

@@ -6,9 +6,10 @@ import (
 )
 
 type IPRateLimiter struct {
-	ips *lru.Cache
-	r   rate.Limit
-	b   int
+	ips *lru.Cache // LRU cache to store IP addresses and their associated rate limiters
+	r   rate.Limit // the rate limit, e.g., 5 requests per second
+	b   int        // the burst size, e.g., allowing a burst of 10 requests at once. The rate limiter gets into action
+	// only after this number exceeds
 }
 
 func NewIPRateLimiter(r rate.Limit, b int, size int) (*IPRateLimiter, error) {
@@ -26,7 +27,7 @@ func NewIPRateLimiter(r rate.Limit, b int, size int) (*IPRateLimiter, error) {
 	return i, nil
 }
 
-func (i *IPRateLimiter) AddIP(ip string) *rate.Limiter {
+func (i *IPRateLimiter) addIP(ip string) *rate.Limiter {
 	limiter := rate.NewLimiter(i.r, i.b)
 
 	i.ips.Add(ip, limiter)
@@ -39,5 +40,5 @@ func (i *IPRateLimiter) GetLimiter(ip string) *rate.Limiter {
 		return limiter.(*rate.Limiter)
 	}
 
-	return i.AddIP(ip)
+	return i.addIP(ip)
 }