package storage import ( "fmt" "io" "io/ioutil" "net/url" "os" "sort" "strconv" "github.com/chrislusf/seaweedfs/weed/glog" "github.com/chrislusf/seaweedfs/weed/operation" "github.com/chrislusf/seaweedfs/weed/storage/needle" "github.com/chrislusf/seaweedfs/weed/util" ) // The volume sync with a master volume via 2 steps: // 1. The slave checks master side to find subscription checkpoint // to setup the replication. // 2. The slave receives the updates from master /* Assume the slave volume needs to follow the master volume. The master volume could be compacted, and could be many files ahead of slave volume. Step 1: The slave volume will ask the master volume for a snapshot of (existing file entries, last offset, number of compacted times). For each entry x in master existing file entries: if x does not exist locally: add x locally For each entry y in local slave existing file entries: if y does not exist on master: delete y locally Step 2: After this, use the last offset and number of compacted times to request the master volume to send a new file, and keep looping. If the number of compacted times is changed, go back to step 1 (very likely this can be optimized more later). */ func (v *Volume) Synchronize(volumeServer string) (err error) { var lastCompactRevision uint16 = 0 var compactRevision uint16 = 0 var masterMap *needle.CompactMap for i := 0; i < 3; i++ { if masterMap, _, compactRevision, err = fetchVolumeFileEntries(volumeServer, v.Id); err != nil { return fmt.Errorf("Failed to sync volume %d entries with %s: %v", v.Id, volumeServer, err) } if lastCompactRevision != compactRevision && lastCompactRevision != 0 { if err = v.Compact(0); err != nil { return fmt.Errorf("Compact Volume before synchronizing %v", err) } if err = v.commitCompact(); err != nil { return fmt.Errorf("Commit Compact before synchronizing %v", err) } } lastCompactRevision = compactRevision if err = v.trySynchronizing(volumeServer, masterMap, compactRevision); err == nil { return } } return } type ByOffset []needle.NeedleValue func (a ByOffset) Len() int { return len(a) } func (a ByOffset) Swap(i, j int) { a[i], a[j] = a[j], a[i] } func (a ByOffset) Less(i, j int) bool { return a[i].Offset < a[j].Offset } // trySynchronizing sync with remote volume server incrementally by // make up the local and remote delta. func (v *Volume) trySynchronizing(volumeServer string, masterMap *needle.CompactMap, compactRevision uint16) error { slaveIdxFile, err := os.Open(v.nm.IndexFileName()) if err != nil { return fmt.Errorf("Open volume %d index file: %v", v.Id, err) } defer slaveIdxFile.Close() slaveMap, err := LoadBtreeNeedleMap(slaveIdxFile) if err != nil { return fmt.Errorf("Load volume %d index file: %v", v.Id, err) } var delta []needle.NeedleValue if err := masterMap.Visit(func(needleValue needle.NeedleValue) error { if needleValue.Key == 0 { return nil } if _, ok := slaveMap.Get(uint64(needleValue.Key)); ok { return nil // skip intersection } delta = append(delta, needleValue) return nil }); err != nil { return fmt.Errorf("Add master entry: %v", err) } if err := slaveMap.m.Visit(func(needleValue needle.NeedleValue) error { if needleValue.Key == 0 { return nil } if _, ok := masterMap.Get(needleValue.Key); ok { return nil // skip intersection } needleValue.Size = 0 delta = append(delta, needleValue) return nil }); err != nil { return fmt.Errorf("Remove local entry: %v", err) } // simulate to same ordering of remote .dat file needle entries sort.Sort(ByOffset(delta)) // make up the delta fetchCount := 0 volumeDataContentHandlerUrl := "http://" + volumeServer + "/admin/sync/data" for _, needleValue := range delta { if needleValue.Size == 0 { // remove file entry from local v.removeNeedle(needleValue.Key) continue } // add master file entry to local data file if err := v.fetchNeedle(volumeDataContentHandlerUrl, needleValue, compactRevision); err != nil { glog.V(0).Infof("Fetch needle %v from %s: %v", needleValue, volumeServer, err) return err } fetchCount++ } glog.V(1).Infof("Fetched %d needles from %s", fetchCount, volumeServer) return nil } func fetchVolumeFileEntries(volumeServer string, vid VolumeId) (m *needle.CompactMap, lastOffset uint64, compactRevision uint16, err error) { m = needle.NewCompactMap() syncStatus, err := operation.GetVolumeSyncStatus(volumeServer, vid.String()) if err != nil { return m, 0, 0, err } total := 0 err = operation.GetVolumeIdxEntries(volumeServer, vid.String(), func(key uint64, offset, size uint32) { // println("remote key", key, "offset", offset*NeedlePaddingSize, "size", size) if offset > 0 && size != TombstoneFileSize { m.Set(needle.Key(key), offset, size) } else { m.Delete(needle.Key(key)) } total++ }) glog.V(2).Infof("server %s volume %d, entries %d, last offset %d, revision %d", volumeServer, vid, total, syncStatus.TailOffset, syncStatus.CompactRevision) return m, syncStatus.TailOffset, syncStatus.CompactRevision, err } func (v *Volume) GetVolumeSyncStatus() operation.SyncVolumeResponse { var syncStatus = operation.SyncVolumeResponse{} if stat, err := v.dataFile.Stat(); err == nil { syncStatus.TailOffset = uint64(stat.Size()) } syncStatus.IdxFileSize = v.nm.IndexFileSize() syncStatus.CompactRevision = v.SuperBlock.CompactRevision syncStatus.Ttl = v.SuperBlock.Ttl.String() syncStatus.Replication = v.SuperBlock.ReplicaPlacement.String() return syncStatus } func (v *Volume) IndexFileContent() ([]byte, error) { return v.nm.IndexFileContent() } // removeNeedle removes one needle by needle key func (v *Volume) removeNeedle(key needle.Key) { n := new(Needle) n.Id = uint64(key) v.deleteNeedle(n) } // fetchNeedle fetches a remote volume needle by vid, id, offset // The compact revision is checked first in case the remote volume // is compacted and the offset is invalid any more. func (v *Volume) fetchNeedle(volumeDataContentHandlerUrl string, needleValue needle.NeedleValue, compactRevision uint16) error { // add master file entry to local data file values := make(url.Values) values.Add("revision", strconv.Itoa(int(compactRevision))) values.Add("volume", v.Id.String()) values.Add("id", needleValue.Key.String()) values.Add("offset", strconv.FormatUint(uint64(needleValue.Offset), 10)) values.Add("size", strconv.FormatUint(uint64(needleValue.Size), 10)) glog.V(4).Infof("Fetch %+v", needleValue) return util.GetUrlStream(volumeDataContentHandlerUrl, values, func(r io.Reader) error { b, err := ioutil.ReadAll(r) if err != nil { return fmt.Errorf("Reading from %s error: %v", volumeDataContentHandlerUrl, err) } offset, err := v.AppendBlob(b) if err != nil { return fmt.Errorf("Appending volume %d error: %v", v.Id, err) } // println("add key", needleValue.Key, "offset", offset, "size", needleValue.Size) v.nm.Put(uint64(needleValue.Key), uint32(offset/NeedlePaddingSize), needleValue.Size) return nil }) }