Golang wal.Open函数代码示例

func readWAL(waldir string, snap walpb.Snapshot) (w *wal.WAL, id, cid types.ID, st raftpb.HardState, ents []raftpb.Entry) {
	var (
		err       error
		wmetadata []byte
	)

	repaired := false
	for {
		if w, err = wal.Open(waldir, snap); err != nil {
			plog.Fatalf("open wal error: %v", err)
		}
		if wmetadata, st, ents, err = w.ReadAll(); err != nil {
			w.Close()
			// we can only repair ErrUnexpectedEOF and we never repair twice.
			if repaired || err != io.ErrUnexpectedEOF {
				plog.Fatalf("read wal error (%v) and cannot be repaired", err)
			}
			if !wal.Repair(waldir) {
				plog.Fatalf("WAL error (%v) cannot be repaired", err)
			} else {
				plog.Infof("repaired WAL error (%v)", err)
				repaired = true
			}
			continue
		}
		break
	}
	var metadata pb.Metadata
	pbutil.MustUnmarshal(&metadata, wmetadata)
	id = types.ID(metadata.NodeID)
	cid = types.ID(metadata.ClusterID)
	return
}

// Open returns a new WAL object with the given encrypters and decrypters.
func (wc walCryptor) Open(dirpath string, snap walpb.Snapshot) (WAL, error) {
	w, err := wal.Open(dirpath, snap)
	if err != nil {
		return nil, err
	}
	return &wrappedWAL{
		WAL:       w,
		encrypter: wc.encrypter,
		decrypter: wc.decrypter,
	}, nil
}

func readWAL(waldir string, index uint64) (w *wal.WAL, id, cid types.ID, st raftpb.HardState, ents []raftpb.Entry) {
	var err error
	if w, err = wal.Open(waldir, index); err != nil {
		log.Fatalf("etcdserver: open wal error: %v", err)
	}
	var wmetadata []byte
	if wmetadata, st, ents, err = w.ReadAll(); err != nil {
		log.Fatalf("etcdserver: read wal error: %v", err)
	}
	var metadata pb.Metadata
	pbutil.MustUnmarshal(&metadata, wmetadata)
	id = types.ID(metadata.NodeID)
	cid = types.ID(metadata.ClusterID)
	return
}

func dump5(dataDir string) ([]raftpb.Entry, error) {
	wd5 := walDir5(dataDir)
	if !wal.Exist(wd5) {
		return nil, fmt.Errorf("No wal exists at %s", wd5)
	}

	w, err := wal.Open(wd5, walpb.Snapshot{})
	if err != nil {
		return nil, err
	}
	defer w.Close()

	_, _, ents, err := w.ReadAll()
	return ents, err
}

// openWAL returns a WAL ready for reading.
func (rc *raftNode) openWAL() *wal.WAL {
	if wal.Exist(rc.waldir) == false {
		if err := os.Mkdir(rc.waldir, 0750); err != nil {
			log.Fatalf("raftexample: cannot create dir for wal (%v)", err)
		}

		w, err := wal.Create(rc.waldir, nil)
		if err != nil {
			log.Fatalf("raftexample: create wal error (%v)", err)
		}
		w.Close()
	}

	w, err := wal.Open(rc.waldir, walpb.Snapshot{})
	if err != nil {
		log.Fatalf("raftexample: error loading wal (%v)", err)
	}

	return w
}

func main() {
	from := flag.String("data-dir", "", "")
	flag.Parse()
	if *from == "" {
		log.Fatal("Must provide -data-dir flag")
	}

	ss := snap.New(snapDir(*from))
	snapshot, err := ss.Load()
	var walsnap walpb.Snapshot
	switch err {
	case nil:
		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
		nodes := genIDSlice(snapshot.Metadata.ConfState.Nodes)
		fmt.Printf("Snapshot:\nterm=%d index=%d nodes=%s\n",
			walsnap.Term, walsnap.Index, nodes)
	case snap.ErrNoSnapshot:
		fmt.Printf("Snapshot:\nempty\n")
	default:
		log.Fatalf("Failed loading snapshot: %v", err)
	}

	w, err := wal.Open(walDir(*from), walsnap)
	if err != nil {
		log.Fatalf("Failed opening WAL: %v", err)
	}
	wmetadata, state, ents, err := w.ReadAll()
	w.Close()
	if err != nil {
		log.Fatalf("Failed reading WAL: %v", err)
	}
	id, cid := parseWALMetadata(wmetadata)
	vid := types.ID(state.Vote)
	fmt.Printf("WAL metadata:\nnodeID=%s clusterID=%s term=%d commitIndex=%d vote=%s\n",
		id, cid, state.Term, state.Commit, vid)

	fmt.Printf("WAL entries:\n")
	fmt.Printf("lastIndex=%d\n", ents[len(ents)-1].Index)
	fmt.Printf("%4s\t%10s\ttype\tdata\n", "term", "index")
	for _, e := range ents {
		msg := fmt.Sprintf("%4d\t%10d", e.Term, e.Index)
		switch e.Type {
		case raftpb.EntryNormal:
			msg = fmt.Sprintf("%s\tnorm", msg)
			var r etcdserverpb.Request
			if err := r.Unmarshal(e.Data); err != nil {
				msg = fmt.Sprintf("%s\t???", msg)
				break
			}
			switch r.Method {
			case "":
				msg = fmt.Sprintf("%s\tnoop", msg)
			case "SYNC":
				msg = fmt.Sprintf("%s\tmethod=SYNC time=%q", msg, time.Unix(0, r.Time))
			case "QGET", "DELETE":
				msg = fmt.Sprintf("%s\tmethod=%s path=%s", msg, r.Method, excerpt(r.Path, 64, 64))
			default:
				msg = fmt.Sprintf("%s\tmethod=%s path=%s val=%s", msg, r.Method, excerpt(r.Path, 64, 64), excerpt(r.Val, 128, 0))
			}
		case raftpb.EntryConfChange:
			msg = fmt.Sprintf("%s\tconf", msg)
			var r raftpb.ConfChange
			if err := r.Unmarshal(e.Data); err != nil {
				msg = fmt.Sprintf("%s\t???", msg)
			} else {
				msg = fmt.Sprintf("%s\tmethod=%s id=%s", msg, r.Type, types.ID(r.NodeID))
			}
		}
		fmt.Println(msg)
	}
}

func (n *Node) readWAL(ctx context.Context, snapshot *raftpb.Snapshot, forceNewCluster bool) (err error) {
	var (
		walsnap  walpb.Snapshot
		metadata []byte
		st       raftpb.HardState
		ents     []raftpb.Entry
	)

	if snapshot != nil {
		walsnap.Index = snapshot.Metadata.Index
		walsnap.Term = snapshot.Metadata.Term
	}

	repaired := false
	for {
		if n.wal, err = wal.Open(n.walDir(), walsnap); err != nil {
			return fmt.Errorf("open wal error: %v", err)
		}
		if metadata, st, ents, err = n.wal.ReadAll(); err != nil {
			if err := n.wal.Close(); err != nil {
				return err
			}
			// we can only repair ErrUnexpectedEOF and we never repair twice.
			if repaired || err != io.ErrUnexpectedEOF {
				return fmt.Errorf("read wal error (%v) and cannot be repaired", err)
			}
			if !wal.Repair(n.walDir()) {
				return fmt.Errorf("WAL error (%v) cannot be repaired", err)
			}
			log.G(ctx).Infof("repaired WAL error (%v)", err)
			repaired = true
			continue
		}
		break
	}

	defer func() {
		if err != nil {
			if walErr := n.wal.Close(); walErr != nil {
				n.Config.Logger.Errorf("error closing raft WAL: %v", walErr)
			}
		}
	}()

	var raftNode api.RaftMember
	if err := raftNode.Unmarshal(metadata); err != nil {
		return fmt.Errorf("error unmarshalling wal metadata: %v", err)
	}
	n.Config.ID = raftNode.RaftID

	if forceNewCluster {
		// discard the previously uncommitted entries
		for i, ent := range ents {
			if ent.Index > st.Commit {
				log.G(context.Background()).Infof("discarding %d uncommitted WAL entries ", len(ents)-i)
				ents = ents[:i]
				break
			}
		}

		// force append the configuration change entries
		toAppEnts := createConfigChangeEnts(getIDs(snapshot, ents), uint64(n.Config.ID), st.Term, st.Commit)
		ents = append(ents, toAppEnts...)

		// force commit newly appended entries
		err := n.wal.Save(st, toAppEnts)
		if err != nil {
			log.G(context.Background()).Fatalf("%v", err)
		}
		if len(toAppEnts) != 0 {
			st.Commit = toAppEnts[len(toAppEnts)-1].Index
		}
	}

	if snapshot != nil {
		if err := n.raftStore.ApplySnapshot(*snapshot); err != nil {
			return err
		}
	}
	if err := n.raftStore.SetHardState(st); err != nil {
		return err
	}
	if err := n.raftStore.Append(ents); err != nil {
		return err
	}

	return nil
}

func main() {
	from := flag.String("data-dir", "", "")
	snapfile := flag.String("start-snap", "", "The base name of snapshot file to start dumping")
	index := flag.Uint64("start-index", 0, "The index to start dumping")
	flag.Parse()
	if *from == "" {
		log.Fatal("Must provide -data-dir flag.")
	}
	if *snapfile != "" && *index != 0 {
		log.Fatal("start-snap and start-index flags cannot be used together.")
	}

	var (
		walsnap  walpb.Snapshot
		snapshot *raftpb.Snapshot
		err      error
	)

	isIndex := *index != 0

	if isIndex {
		fmt.Printf("Start dumping log entries from index %d.\n", *index)
		walsnap.Index = *index
	} else {
		if *snapfile == "" {
			ss := snap.New(snapDir(*from))
			snapshot, err = ss.Load()
		} else {
			snapshot, err = snap.Read(path.Join(snapDir(*from), *snapfile))
		}

		switch err {
		case nil:
			walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
			nodes := genIDSlice(snapshot.Metadata.ConfState.Nodes)
			fmt.Printf("Snapshot:\nterm=%d index=%d nodes=%s\n",
				walsnap.Term, walsnap.Index, nodes)
		case snap.ErrNoSnapshot:
			fmt.Printf("Snapshot:\nempty\n")
		default:
			log.Fatalf("Failed loading snapshot: %v", err)
		}
		fmt.Println("Start dupmping log entries from snapshot.")
	}

	w, err := wal.Open(walDir(*from), walsnap)
	if err != nil {
		log.Fatalf("Failed opening WAL: %v", err)
	}
	wmetadata, state, ents, err := w.ReadAll()
	w.Close()
	if err != nil && (!isIndex || err != wal.ErrSnapshotNotFound) {
		log.Fatalf("Failed reading WAL: %v", err)
	}
	id, cid := parseWALMetadata(wmetadata)
	vid := types.ID(state.Vote)
	fmt.Printf("WAL metadata:\nnodeID=%s clusterID=%s term=%d commitIndex=%d vote=%s\n",
		id, cid, state.Term, state.Commit, vid)

	fmt.Printf("WAL entries:\n")
	fmt.Printf("lastIndex=%d\n", ents[len(ents)-1].Index)
	fmt.Printf("%4s\t%10s\ttype\tdata\n", "term", "index")
	for _, e := range ents {
		msg := fmt.Sprintf("%4d\t%10d", e.Term, e.Index)
		switch e.Type {
		case raftpb.EntryNormal:
			msg = fmt.Sprintf("%s\tnorm", msg)
			var r etcdserverpb.Request
			if err := r.Unmarshal(e.Data); err != nil {
				msg = fmt.Sprintf("%s\t???", msg)
				break
			}
			switch r.Method {
			case "":
				msg = fmt.Sprintf("%s\tnoop", msg)
			case "SYNC":
				msg = fmt.Sprintf("%s\tmethod=SYNC time=%q", msg, time.Unix(0, r.Time))
			case "QGET", "DELETE":
				msg = fmt.Sprintf("%s\tmethod=%s path=%s", msg, r.Method, excerpt(r.Path, 64, 64))
			default:
				msg = fmt.Sprintf("%s\tmethod=%s path=%s val=%s", msg, r.Method, excerpt(r.Path, 64, 64), excerpt(r.Val, 128, 0))
			}
		case raftpb.EntryConfChange:
			msg = fmt.Sprintf("%s\tconf", msg)
			var r raftpb.ConfChange
			if err := r.Unmarshal(e.Data); err != nil {
				msg = fmt.Sprintf("%s\t???", msg)
			} else {
				msg = fmt.Sprintf("%s\tmethod=%s id=%s", msg, r.Type, types.ID(r.NodeID))
			}
		}
		fmt.Println(msg)
	}
}