Rate Limits

retry() {
  local url=$1
  for attempt in 1 2 3 4 5; do
    response=$(curl -sS -D /tmp/hdr -o /tmp/body -w "%{http_code}" "$url" \
      -H "Authorization: DPoP $ANTON_ACCESS_TOKEN")
    if [ "$response" != "429" ]; then
      cat /tmp/body
      return 0
    fi
    retry_after=$(grep -i '^retry-after:' /tmp/hdr | awk '{print $2}' | tr -d '\r')
    sleep "${retry_after:-1}"
  done
  echo "rate limit: retry budget exhausted" >&2
  return 1
}

async function requestWithBackoff(url, init = {}, attempt = 1) {
  const response = await fetch(url, init);
  if (response.status !== 429) return response;

  if (attempt > 5) throw new Error("rate limit: retry budget exhausted");

  const retryAfter = Number(response.headers.get("retry-after")) || 1;
  const jitter = Math.random() * 500;
  await new Promise((r) => setTimeout(r, retryAfter * 1000 + jitter));

  return requestWithBackoff(url, init, attempt + 1);
}

function requestWithBackoff(string $url, array $opts, int $attempt = 1): string {
    $ch = curl_init($url);
    curl_setopt_array($ch, $opts + [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_HEADER => true,
    ]);
    $raw = curl_exec($ch);
    $status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if ($status !== 429) return $raw;
    if ($attempt > 5) throw new RuntimeException("rate limit: retry budget exhausted");

    preg_match('/retry-after:\s*(\d+)/i', $raw, $m);
    $wait = ((int)($m[1] ?? 1)) + (mt_rand(0, 500) / 1000);
    usleep((int)($wait * 1_000_000));

    return requestWithBackoff($url, $opts, $attempt + 1);
}

func DoWithBackoff(req *http.Request) (*http.Response, error) {
    for attempt := 1; attempt <= 5; attempt++ {
        resp, err := http.DefaultClient.Do(req)
        if err != nil {
            return nil, err
        }
        if resp.StatusCode != http.StatusTooManyRequests {
            return resp, nil
        }
        retryAfter, _ := strconv.Atoi(resp.Header.Get("Retry-After"))
        if retryAfter < 1 {
            retryAfter = 1
        }
        resp.Body.Close()
        jitter := time.Duration(rand.Intn(500)) * time.Millisecond
        time.Sleep(time.Duration(retryAfter)*time.Second + jitter)
    }
    return nil, errors.New("rate limit: retry budget exhausted")
}