Method Map

worker/restore_map.go:685–714

Map reads the backup, converts the keys and values to the required format, and loads them to the given badger DB. The set of predicates is used to avoid restoring values from predicates no longer assigned to this group. If restoreTs is greater than zero, the key-value pairs will be written with that

(r io.Reader, in *loadBackupInput)

// Otherwise, the original value is used.
// TODO(DGRAPH-1234): Check whether restoreTs can be removed.
func (m *mapper) Map(r io.Reader, in *loadBackupInput) error {
	br := bufio.NewReaderSize(r, 16<<10)
	zbuf := z.NewBuffer(bufSz, "Restore.Map")

	for {
		var sz uint64
		err := binary.Read(br, binary.LittleEndian, &sz)
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}

		m.szHist.Update(int64(sz))
		buf := zbuf.SliceAllocate(int(sz))
		if _, err = io.ReadFull(br, buf); err != nil {
			return err
		}

		if zbuf.LenNoPadding() > bufSoftLimit {
			atomic.AddUint64(&m.bytesRead, uint64(zbuf.LenNoPadding()))
			glog.Infof("Sending req of size: %s\n", humanize.IBytes(uint64(zbuf.LenNoPadding())))
			m.reqCh <- listReq{zbuf, in}
			zbuf = z.NewBuffer(bufSz, "Restore.Map")
		}
	}
	m.reqCh <- listReq{zbuf, in}
	return nil
}

type mapResult struct {
	maxUid uint64