/*
此api实现复制写入操作 步骤如下:
1.先写入本地
2. 如果需要复制则 将消息投递replicate到master
3. 如果2操作成功完成则返回
4. 如果2失败,则删除本地副本并投递删除消息到master
5. 返回4的结果
同理删除
*/
func ReplicatedWrite(masterNode string, s *storage.Store, volumeId storage.VolumeId, needle *storage.Needle, r *http.Request) (size uint32, errorStatus string) {
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 { //写入成功
needToReplicate = needToReplicate || s.GetVolume(volumeId).NeedToReplicate()
} else {
errorStatus = "Failed to write to local disk"
}
//??? --lewgun
if !needToReplicate && ret > 0 {
needToReplicate = s.GetVolume(volumeId).NeedToReplicate()
}
if needToReplicate { //send to other replica locations
if r.FormValue("type") != "replicate" { //只有最原始的才会执行distributedOperation
//向master复制
if !distributedOperation(masterNode,
s,
volumeId,
func(location operation.Location) bool {
_, err := operation.Upload(
"http://"+location.Url+r.URL.Path+"?type=replicate&ts="+strconv.FormatUint(needle.LastModified, 10),
string(needle.Name),
bytes.NewReader(needle.Data),
needle.IsGzipped(),
string(needle.Mime))
return err == nil
})
{
ret = 0
errorStatus = "Failed to write to replicas for volume " + volumeId.String()
}// if !distributedOperation(masterNode,
} // if r.FormValue("type") != "replicate" {
}
//复制失败,删除本地副本
if errorStatus != "" {
if _, err = s.Delete(volumeId, needle); err != nil {
errorStatus += "\nCannot delete " + strconv.FormatUint(needle.Id, 10) + " from " +
volumeId.String() + ": " + err.Error()
} else {
distributedOperation(
masterNode,
s,
volumeId,
func(location operation.Location) bool {
return nil == util.Delete("http://"+location.Url+r.URL.Path+"?type=replicate")
}
) // distributedOperation(...)
} // if errorStatus != "" {
}
size = ret
return
}
func submitForClientHandler(w http.ResponseWriter, r *http.Request, masterUrl string) {
m := make(map[string]interface{})
if r.Method != "POST" {
m["error"] = "Only submit via POST!"
writeJsonQuiet(w, r, m)
return
}
debug("parsing upload file...")
//解析上传文件
fname, data, mimeType, isGzipped, lastModified, _, pe := storage.ParseUpload(r)
if pe != nil {
writeJsonError(w, r, pe)
return
}
debug("assigning file id for", fname)
//为文件分配id
assignResult, ae := operation.Assign(masterUrl, 1, r.FormValue("replication"), r.FormValue("collection"), r.FormValue("ttl"))
if ae != nil {
writeJsonError(w, r, ae)
return
}
url := "http://" + assignResult.PublicUrl + "/" + assignResult.Fid
if lastModified != 0 {
url = url + "?ts=" + strconv.FormatUint(lastModified, 10)
}
debug("upload file to store", url)
//上传文件
uploadResult, err := operation.Upload(url, fname, bytes.NewReader(data), isGzipped, mimeType)
if err != nil {
writeJsonError(w, r, err)
return
}
//返回成功后的处理消息
m["fileName"] = fname
m["fid"] = assignResult.Fid
m["fileUrl"] = assignResult.PublicUrl + "/" + assignResult.Fid
m["size"] = uploadResult.Size
writeJsonQuiet(w, r, m)
return
}