/*
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 ReplicatedDelete(masterNode string, store *storage.Store, volumeId storage.VolumeId, n *storage.Needle, r *http.Request) (ret uint32) {
ret, err := store.Delete(volumeId, n)
if err != nil {
glog.V(0).Infoln("delete error:", err)
return
}
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 !distributedOperation(masterNode, store, volumeId, func(location operation.Location) bool {
return nil == util.Delete("http://"+location.Url+r.URL.Path+"?type=replicate")
}) {
ret = 0
}
}
}
return
}