feat: add cache helpers

cache/retry.go

@@ -0,0 +1,42 @@
+package cache
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+type retry struct {
+	transport http.RoundTripper
+	retry     int
+}
+
+func (t *retry) RoundTrip(req *http.Request) (*http.Response, error) {
+	var body []byte
+	if req.Body != nil {
+		body, _ = io.ReadAll(req.Body)
+	}
+
+	for count := 0; count < t.retry; count++ {
+		req.Body = io.NopCloser(bytes.NewBuffer(body))
+		res, err := t.transport.RoundTrip(req)
+		if err != nil {
+			return nil, err
+		}
+		if t.check(res) {
+			if res.Body != nil {
+				io.Copy(io.Discard, res.Body)
+				res.Body.Close()
+			}
+			continue
+		}
+		return res, err
+	}
+
+	return nil, fmt.Errorf("too many retries")
+}
+
+func (t *retry) check(res *http.Response) bool {
+	return res.StatusCode > 399
+}