chmike · December 18, 2023 15:31 · Dec 18, 2023
diff --git a/simpleRateLimiter.go b/simpleRateLimiter.go
@@ -0,0 +1,43 @@
+// NewRateLimiter returns a rate limiter function returning false 
+// when the event must be rejected, and true when it must be accepted. 
+// The rate is expressed in Hz (events/seconds). It simply ensures that
+// the time interval between two accept satisfies the rate criteria. It
+// is equivalent to the token bucket algorithm with a bucket size of one.
+func NewRateLimiter(rate float64) func() bool {
+	var stamp time.Time // time stamp of last accepted event
+	return func() bool {
+		now := time.Now()
+		if now.Sub(stamp).Seconds() *rate < 1. {
+			return false
+		}
+		stamp = now
+		return true
+	}
+}
+
+// The following is a usage example with a rate limiting middelware.
+func rateLimiter(rate float64, f http.HandlerFunc) http.HandlerFunc {
+  rl := NewRateLimiter(rate)
+  return func(w http.ResponseWriter, r *http.Request) {
+    if !rl() {
+      http.Error(w, "too many requests, retry later", http.StatusTooManyRequests)
+      return
+    }
+    f(w, r)
+  }
+}
+
+// some example server action
+func hello(w http.ResponseWriter, r *http.Request) {
+  fmt.Fprintln(w, "hello !")
+}
+
+func main() {
+  http.HandleFunc("/", rateLimiter(1, hello)) // accept at most one request per second
+  http.ListenAndServe(":8080", nil)
+}
+
+
+
+
+