func()

in client/client.go [147:209]

• 53 lines of code
• 16 McCabe index (conditional complexity)

func (hs *httpSource) Index(ctx context.Context) (_ DBIndex, err error) {
	defer derrors.Wrap(&err, "Index()")

	var cachedIndex DBIndex
	var cachedIndexRetrieved *time.Time

	if hs.cache != nil {
		index, retrieved, err := hs.cache.ReadIndex(hs.dbName)
		if err != nil {
			return nil, err
		}

		cachedIndex = index
		if cachedIndex != nil {
			if time.Since(retrieved) < time.Hour*2 {
				return cachedIndex, nil
			}

			cachedIndexRetrieved = &retrieved
		}
	}

	req, err := http.NewRequestWithContext(ctx, "GET", fmt.Sprintf("%s/index.json", hs.url), nil)
	if err != nil {
		return nil, err
	}
	if cachedIndexRetrieved != nil {
		req.Header.Add("If-Modified-Since", cachedIndexRetrieved.Format(http.TimeFormat))
	}
	resp, err := hs.c.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if cachedIndexRetrieved != nil && resp.StatusCode == http.StatusNotModified {
		// If status has not been modified, this is equivalent to returning the
		// same index. We update the timestamp so the next cache index read does
		// not require a roundtrip to the server.
		if err = hs.cache.WriteIndex(hs.dbName, cachedIndex, time.Now()); err != nil {
			return nil, err
		}
		return cachedIndex, nil
	}
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
	}
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	var index DBIndex
	if err = json.Unmarshal(b, &index); err != nil {
		return nil, err
	}

	if hs.cache != nil {
		if err = hs.cache.WriteIndex(hs.dbName, index, time.Now()); err != nil {
			return nil, err
		}
	}

	return index, nil
}