Minor fix to google books ratelimit response

googlebooks.go

@@ -126,9 +126,11 @@ func googleBooksGet(uri string) (*http.Response, error) {
 		<-gbSemaphore
 	}()
 
-	// Set a deadline to 1 hour.
+	// Set a deadline to 10 minutes.
+	timeout := 900 * time.Second
 	backoff := 500 * time.Millisecond
-	deadline := time.Now().Add(3600 * time.Second)
+	maxBackoff := 60 * time.Second
+	deadline := time.Now().Add(timeout)
 	for time.Now().Before(deadline) {
 		resp, err := http.Get(uri)
 		if err != nil {
@@ -140,6 +142,9 @@ func googleBooksGet(uri string) (*http.Response, error) {
 			resp.Body.Close()
 			time.Sleep(backoff)
 			backoff += backoff / 2
+			if backoff > maxBackoff {
+				backoff = maxBackoff
+			}
 			continue
 		case 200:
 			return resp, nil