94 lines
2.0 KiB
Go
94 lines
2.0 KiB
Go
package snap
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import (
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"encoding/json"
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"errors"
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"fmt"
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"hash/crc32"
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"io/ioutil"
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"log"
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"os"
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"path"
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"sort"
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"github.com/coreos/etcd/raft"
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)
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var (
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ErrNoSnapshot = errors.New("snap: no available snapshot")
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ErrCRCMismatch = errors.New("snap: crc mismatch")
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crcTable = crc32.MakeTable(crc32.Castagnoli)
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)
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type Snapshotter struct {
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dir string
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}
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func New(dir string) *Snapshotter {
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return &Snapshotter{
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dir: dir,
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}
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}
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func (s *Snapshotter) Save(snapshot *raft.Snapshot) error {
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fname := fmt.Sprintf("%016x-%016x-%016x.snap", snapshot.ClusterId, snapshot.Term, snapshot.Index)
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// TODO(xiangli): make raft.Snapshot a protobuf type
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b, err := json.Marshal(snapshot)
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if err != nil {
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panic(err)
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}
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crc := crc32.Update(0, crcTable, b)
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snap := Snapshot{Crc: crc, Data: b}
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d, err := snap.Marshal()
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if err != nil {
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return err
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}
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return ioutil.WriteFile(path.Join(s.dir, fname), d, 0666)
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}
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func (s *Snapshotter) Load() (*raft.Snapshot, error) {
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dir, err := os.Open(s.dir)
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if err != nil {
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return nil, err
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}
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defer dir.Close()
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names, err := dir.Readdirnames(-1)
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if err != nil {
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return nil, err
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}
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if len(names) == 0 {
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return nil, ErrNoSnapshot
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}
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sort.Sort(sort.Reverse(sort.StringSlice(names)))
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var snap raft.Snapshot
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var serializedSnap Snapshot
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var b []byte
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for _, name := range names {
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b, err = ioutil.ReadFile(path.Join(s.dir, name))
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if err != nil {
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log.Printf("Snapshotter cannot read file %v: %v", name, err)
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continue
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}
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if err = serializedSnap.Unmarshal(b); err != nil {
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log.Printf("Corrupted snapshot file %v: %v", name, err)
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continue
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}
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crc := crc32.Update(0, crcTable, serializedSnap.Data)
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if crc != serializedSnap.Crc {
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log.Printf("Corrupted snapshot file %v: crc mismatch", name)
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err = ErrCRCMismatch
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continue
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}
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if err = json.Unmarshal(serializedSnap.Data, &snap); err != nil {
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log.Printf("Corrupted snapshot file %v: %v", name, err)
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continue
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}
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break
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}
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if err != nil {
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return nil, err
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}
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return &snap, nil
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}
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