func ReplicatedDelete(masterNode string, store *storage.Store,
	volumeId storage.VolumeId, n *storage.Needle,
	r *http.Request) (uint32, error) {

	//check JWT
	jwt := security.GetJwt(r)

	ret, err := store.Delete(volumeId, n)
	if err != nil {
		glog.V(0).Infoln("delete error:", err)
		return ret, err
	}

	needToReplicate := !store.HasVolume(volumeId)
	if !needToReplicate && ret > 0 {
		needToReplicate = store.GetVolume(volumeId).NeedToReplicate()
	}
	if needToReplicate { //send to other replica locations
		if r.FormValue("type") != "replicate" {
			if err = distributedOperation(masterNode, store, volumeId, func(location operation.Location) error {
				return util.Delete("http://"+location.Url+r.URL.Path+"?type=replicate", jwt)
			}); err != nil {
				ret = 0
			}
		}
	}
	return ret, err
}
func ReplicatedWrite(masterNode string, s *storage.Store,
	volumeId storage.VolumeId, needle *storage.Needle,
	r *http.Request) (size uint32, errorStatus string) {

	//check JWT
	jwt := security.GetJwt(r)

	ret, err := s.Write(volumeId, needle)
	needToReplicate := !s.HasVolume(volumeId)
	if err != nil {
		errorStatus = "Failed to write to local disk (" + err.Error() + ")"
	} else if ret > 0 {
		needToReplicate = needToReplicate || s.GetVolume(volumeId).NeedToReplicate()
	} else {
		errorStatus = "Failed to write to local disk"
	}
	if !needToReplicate && ret > 0 {
		needToReplicate = s.GetVolume(volumeId).NeedToReplicate()
	}
	if needToReplicate { //send to other replica locations
		if r.FormValue("type") != "replicate" {

			if err = distributedOperation(masterNode, s, volumeId, func(location operation.Location) error {
				u := url.URL{
					Scheme: "http",
					Host:   location.Url,
					Path:   r.URL.Path,
				}
				q := url.Values{
					"type": {"replicate"},
				}
				if needle.LastModified > 0 {
					q.Set("ts", strconv.FormatUint(needle.LastModified, 10))
				}
				if needle.IsChunkedManifest() {
					q.Set("cm", "true")
				}
				u.RawQuery = q.Encode()
				_, err := operation.Upload(u.String(),
					string(needle.Name), bytes.NewReader(needle.Data), needle.IsGzipped(), string(needle.Mime),
					jwt)
				return err
			}); err != nil {
				ret = 0
				errorStatus = fmt.Sprintf("Failed to write to replicas for volume %d: %v", volumeId, err)
			}
		}
	}
	size = ret
	return
}