Add basic v1.2 snapshot writer

Author: viciious

snapio/snapwrite.go

@@ -0,0 +1,77 @@
+package snapio
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"io"
+
+	"github.com/tinylib/msgp/msgp"
+	"github.com/viciious/go-tarantool"
+)
+
+type SpaceData struct {
+	Space  uint
+	Tuples [][]interface{}
+}
+
+func WriteV12Snapshot(fd io.Writer, data []*SpaceData) error {
+	header := `SNAP
+0.12
+Version: 2.2.1-3-g878e2a42c
+Instance: d31ad582-66a6-4b18-96f7-278a7a33ad20
+VClock: {1: 10001}
+
+`
+
+	w := bufio.NewWriter(fd)
+	defer w.Flush()
+
+	_, err := w.WriteString(header)
+	if err != nil {
+		return err
+	}
+
+	var lsn uint
+	for _, s := range data {
+		space := s.Space
+		if space == 0 {
+			space = 10024
+		}
+		for _, t := range s.Tuples {
+			var arr []byte
+
+			arr = msgp.AppendMapHeader(arr, 1)
+			arr = msgp.AppendUint(arr, tarantool.KeyLSN)
+			arr = msgp.AppendUint(arr, uint(lsn+1))
+
+			arr = msgp.AppendMapHeader(arr, 2)
+			arr = msgp.AppendUint(arr, tarantool.KeySpaceNo)
+			arr = msgp.AppendUint(arr, uint(space))
+			arr = msgp.AppendUint(arr, tarantool.KeyTuple)
+			arr, _ = msgp.AppendIntf(arr, t)
+
+			var lenbuf []byte
+			lenbuf = msgp.AppendUint32(lenbuf, uint32(len(arr)))
+
+			if err = binary.Write(w, binary.BigEndian, uint32(XRowFixedHeaderMagic)); err != nil {
+				return err
+			}
+			if _, err = w.Write(lenbuf); err != nil {
+				return err
+			}
+			if _, err = w.Write(bytes.Repeat([]byte{'\x00'}, XRowFixedHeaderSize-len(lenbuf)-4)); err != nil {
+				return err
+			}
+			if _, err = w.Write(arr); err != nil {
+				return err
+			}
+		}
+	}
+
+	if err = binary.Write(w, binary.BigEndian, uint32(XRowFixedHeaderEof)); err != nil {
+		return err
+	}
+
+	return nil
+}