func (this *fdfsClient) downloadToBufferByOffset(fileId string, offset int64, downloadSize int64, catInstance cat.Cat) ([]byte, error) {
//split file id to two parts: group name and file name
tmp, err := splitRemoteFileId(fileId)
if err != nil || len(tmp) != 2 {
return nil, err
}
groupName := tmp[0]
fileName := tmp[1]
//query a download server from tracker
storeInfo, err := this.tracker.trackerQueryStorageFetch(groupName, fileName)
if err != nil {
return nil, err
}
if catInstance != nil {
event := catInstance.NewEvent("ImgFromStorage", fmt.Sprintf("%s:%s", storeInfo.groupName, storeInfo.ipAddr))
event.SetStatus("0")
event.Complete()
}
//get a storage client from storage map, if not exist, create a new storage client
storeClient, err := this.getStorage(storeInfo.ipAddr, storeInfo.port)
if err != nil {
return nil, err
}
return storeClient.storageDownload(storeInfo, offset, downloadSize, fileName)
}
func logEvent(cat cat.Cat, title string, name string, data map[string]string) {
event := cat.NewEvent(title, name)
if data != nil {
for k, v := range data {
event.AddData(k, v)
}
}
event.SetStatus("0")
event.Complete()
}