Refactor: let 'time' module do the math

Enhance/Fix: handle second variant of 'retry-after' header

Signed-off-by: Jiri Vrba <[email protected]>

src/pkg/reg/adapter/dockerhub/adapter.go

@@ -147,20 +147,27 @@ func (a *adapter) limitAwareDo(method string, path string, body io.Reader) (*htt
 			if reqsLeft < 8 {
 				resetTSC, err := strconv.ParseInt(clientResp.Header.Get("x-ratelimit-reset"), 10, 64)
 				if err == nil {
-					seconds := resetTSC - time.Now().Unix()
-					log.Infof("Ratelimit exhaustion eminent, sleeping for %d seconds", seconds)
-					time.Sleep(time.Duration(seconds) * time.Second)
+					dur := time.Until(time.Unix(resetTSC, 0))
+					log.Infof("Rate-limit exhaustion eminent, sleeping for %.1f seconds", dur.Seconds())
+					time.Sleep(dur)
 					log.Info("Sleep finished, resuming operation")
 				}
+				return clientResp, clientErr
 			}
-			return clientResp, clientErr
 		}
+		var dur = time.Duration(0)
 		seconds, err := strconv.ParseInt(clientResp.Header.Get("retry-after"), 10, 64)
 		if err != nil {
-			return nil, errors.New("blocked by dockerhub rate-limit and missing retry-after header")
+			expireTime, err := http.ParseTime(clientResp.Header.Get("retry-after"))
+			if err != nil {
+				return nil, errors.New("blocked by dockerhub rate-limit and missing retry-after header")
+			}
+			dur = time.Until(expireTime)
+		} else {
+			dur = time.Duration(seconds) * time.Second
 		}
-		log.Infof("Ratelimit exhausted, sleeping for %d seconds", seconds)
-		time.Sleep(time.Duration(seconds) * time.Second)
+		log.Infof("Rate-limit exhausted, sleeping for %.1f seconds", dur.Seconds())
+		time.Sleep(dur)
 		log.Info("Sleep finished, resuming operation")
 		attemptsLeft--
 	}