Golang Data.UnmarshalBinary方法代碼示例

// MetastoreBackup returns a snapshot of the meta store.
func (c *Client) MetastoreBackup() (*meta.Data, error) {
	req := &Request{
		Type: RequestMetastoreBackup,
	}

	b, err := c.doRequest(req)
	if err != nil {
		return nil, err
	}

	// Check the magic.
	magic := binary.BigEndian.Uint64(b[:8])
	if magic != BackupMagicHeader {
		return nil, errors.New("invalid metadata received")
	}
	i := 8

	// Size of the meta store bytes.
	length := int(binary.BigEndian.Uint64(b[i : i+8]))
	i += 8
	metaBytes := b[i : i+length]
	i += int(length)

	// Unpack meta data.
	var data meta.Data
	if err := data.UnmarshalBinary(metaBytes); err != nil {
		return nil, fmt.Errorf("unmarshal: %s", err)
	}

	return &data, nil
}

// unpackMeta reads the metadata from the backup directory and initializes a raft
// cluster and replaces the root metadata.
func (cmd *Command) unpackMeta() error {
	// find the meta file
	metaFiles, err := filepath.Glob(filepath.Join(cmd.backupFilesPath, backup.Metafile+".*"))
	if err != nil {
		return err
	}

	if len(metaFiles) == 0 {
		return fmt.Errorf("no metastore backups in %s", cmd.backupFilesPath)
	}

	latest := metaFiles[len(metaFiles)-1]

	fmt.Fprintf(cmd.Stdout, "Using metastore snapshot: %v\n", latest)
	// Read the metastore backup
	f, err := os.Open(latest)
	if err != nil {
		return err
	}

	var buf bytes.Buffer
	if _, err := io.Copy(&buf, f); err != nil {
		return fmt.Errorf("copy: %s", err)
	}

	b := buf.Bytes()
	var i int

	// Make sure the file is actually a meta store backup file
	magic := binary.BigEndian.Uint64(b[:8])
	if magic != snapshotter.BackupMagicHeader {
		return fmt.Errorf("invalid metadata file")
	}
	i += 8

	// Size of the meta store bytes
	length := int(binary.BigEndian.Uint64(b[i : i+8]))
	i += 8
	metaBytes := b[i : i+length]
	i += int(length)

	// Size of the node.json bytes
	length = int(binary.BigEndian.Uint64(b[i : i+8]))
	i += 8
	nodeBytes := b[i:]

	// Unpack into metadata.
	var data meta.Data
	if err := data.UnmarshalBinary(metaBytes); err != nil {
		return fmt.Errorf("unmarshal: %s", err)
	}

	// Copy meta config and remove peers so it starts in single mode.
	c := cmd.MetaConfig
	c.Dir = cmd.metadir

	// Create the meta dir
	if os.MkdirAll(c.Dir, 0700); err != nil {
		return err
	}

	// Write node.json back to meta dir
	if err := ioutil.WriteFile(filepath.Join(c.Dir, "node.json"), nodeBytes, 0655); err != nil {
		return err
	}

	client := meta.NewClient(c)
	client.SetLogger(log.New(ioutil.Discard, "", 0))
	if err := client.Open(); err != nil {
		return err
	}
	defer client.Close()

	// Force set the full metadata.
	if err := client.SetData(&data); err != nil {
		return fmt.Errorf("set data: %s", err)
	}

	// remove the raft.db file if it exists
	err = os.Remove(filepath.Join(cmd.metadir, "raft.db"))
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}

	// remove the node.json file if it exists
	err = os.Remove(filepath.Join(cmd.metadir, "node.json"))
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}

	return nil
}

// unpackMeta reads the metadata from the backup directory and initializes a raft
// cluster and replaces the root metadata.
func (cmd *Command) unpackMeta() error {
	// find the meta file
	metaFiles, err := filepath.Glob(filepath.Join(cmd.backupFilesPath, backup.Metafile+".*"))
	if err != nil {
		return err
	}

	if len(metaFiles) == 0 {
		return fmt.Errorf("no metastore backups in %s", cmd.backupFilesPath)
	}

	latest := metaFiles[len(metaFiles)-1]

	fmt.Fprintf(cmd.Stdout, "Using metastore snapshot: %v\n", latest)
	// Read the metastore backup
	f, err := os.Open(latest)
	if err != nil {
		return err
	}

	var buf bytes.Buffer
	if _, err := io.Copy(&buf, f); err != nil {
		return fmt.Errorf("copy: %s", err)
	}

	b := buf.Bytes()
	var i int

	// Make sure the file is actually a meta store backup file
	magic := btou64(b[:8])
	if magic != snapshotter.BackupMagicHeader {
		return fmt.Errorf("invalid metadata file")
	}
	i += 8

	// Size of the meta store bytes
	length := int(btou64(b[i : i+8]))
	i += 8
	metaBytes := b[i : i+length]
	i += int(length)

	// Size of the node.json bytes
	length = int(btou64(b[i : i+8]))
	i += 8
	nodeBytes := b[i:]

	// Unpack into metadata.
	var data meta.Data
	if err := data.UnmarshalBinary(metaBytes); err != nil {
		return fmt.Errorf("unmarshal: %s", err)
	}

	// Copy meta config and remove peers so it starts in single mode.
	c := cmd.MetaConfig
	c.JoinPeers = nil
	c.LoggingEnabled = false

	// Create the meta dir
	if os.MkdirAll(c.Dir, 0700); err != nil {
		return err
	}

	// Write node.json back to meta dir
	if err := ioutil.WriteFile(filepath.Join(c.Dir, "node.json"), nodeBytes, 0655); err != nil {
		return err
	}

	// Initialize meta store.
	store := meta.NewService(c)
	store.RaftListener = newNopListener()

	// Open the meta store.
	if err := store.Open(); err != nil {
		return fmt.Errorf("open store: %s", err)
	}
	defer store.Close()

	// Wait for the store to be ready or error.
	select {
	case err := <-store.Err():
		return err
	default:
	}

	client := meta.NewClient([]string{store.HTTPAddr()}, false)
	client.SetLogger(log.New(ioutil.Discard, "", 0))
	if err := client.Open(); err != nil {
		return err
	}
	defer client.Close()

	// Force set the full metadata.
	if err := client.SetData(&data); err != nil {
		return fmt.Errorf("set data: %s", err)
	}
	return nil
}