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package storage
import (
"fmt"
"io"
"io/ioutil"
"net/url"
"os"
"sort"
"strconv"
"github.com/chrislusf/seaweedfs/go/glog"
"github.com/chrislusf/seaweedfs/go/operation"
"github.com/chrislusf/seaweedfs/go/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 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(); 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 []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 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 := LoadNeedleMap(slaveIdxFile)
if err != nil {
return fmt.Errorf("Load volume %d index file: %v", v.Id, err)
}
var delta []NeedleValue
if err := masterMap.Visit(func(needleValue 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 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 CompactMap, lastOffset uint64, compactRevision uint16, err error) {
m = 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 != 0 {
m.Set(Key(key), offset, size)
} else {
m.Delete(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 Key) {
n := new(Needle)
n.Id = uint64(key)
v.delete(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 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
})
}
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