func fetchFromUpstream(h *fasthttp.RequestHeader, key []byte) *ybc.Item {
upstreamUrl := fmt.Sprintf("%s://%s%s", *upstreamProtocol, *upstreamHost, h.RequestURI())
var req fasthttp.Request
req.SetRequestURI(upstreamUrl)
var resp fasthttp.Response
err := upstreamClient.Do(&req, &resp)
if err != nil {
logRequestError(h, "Cannot make request for [%s]: [%s]", key, err)
return nil
}
if resp.StatusCode() != fasthttp.StatusOK {
logRequestError(h, "Unexpected status code=%d for the response [%s]", resp.StatusCode(), key)
return nil
}
contentType := string(resp.Header.ContentType())
if contentType == "" {
contentType = "application/octet-stream"
}
body := resp.Body()
contentLength := len(body)
itemSize := contentLength + len(contentType) + 1
txn, err := cache.NewSetTxn(key, itemSize, ybc.MaxTtl)
if err != nil {
logRequestError(h, "Cannot start set txn for response [%s], itemSize=%d: [%s]", key, itemSize, err)
return nil
}
if err = storeContentType(h, txn, contentType); err != nil {
txn.Rollback()
return nil
}
n, err := txn.Write(body)
if err != nil {
logRequestError(h, "Cannot read response [%s] body with size=%d to cache: [%s]", key, contentLength, err)
txn.Rollback()
return nil
}
if n != contentLength {
logRequestError(h, "Unexpected number of bytes copied=%d from response [%s] to cache. Expected %d", n, key, contentLength)
txn.Rollback()
return nil
}
item, err := txn.CommitItem()
if err != nil {
logRequestError(h, "Cannot commit set txn for response [%s], size=%d: [%s]", key, contentLength, err)
return nil
}
atomic.AddInt64(&stats.BytesReadFromUpstream, int64(n))
return item
}
func logRequestError(h *fasthttp.RequestHeader, format string, args ...interface{}) {
msg := fmt.Sprintf(format, args...)
logMessage("%s - %s - %s. %s", h.RequestURI(), h.Referer(), h.UserAgent(), msg)
}