initial commit of api

cmd/api/http/middleware.go

@@ -0,0 +1,37 @@
+package http
+
+import (
+	"context"
+	"errors"
+	"math/rand"
+	"net/http"
+)
+
+func (s *Server) rateLimiter(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		token, err := s.RateLimiter.Acquire()
+		if err != nil {
+			panic(err)
+		}
+		ctx := context.WithValue(r.Context(), "rate-limit-token", token)
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+}
+
+func (s *Server) faulty(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		rlExceedPerc := s.RateLimiter.LimitExceededPerc()
+		// Faults will scale to the percentage of requests that are above the limit.
+		// When 2x volume is exceeded all requests should fail.
+		if rlExceedPerc > 0.0 {
+			check := rand.Float32()
+			if rlExceedPerc > float32(check) {
+				s.respondError(w, http.StatusInternalServerError, errors.New("application error"))
+				// Transaction failed so release the token.
+				s.RateLimiter.Release(r.Context().Value("rate-limit-token").(*Token))
+				return
+			}
+		}
+		next.ServeHTTP(w, r)
+	})
+}