gitbase: implement encode and decode for commitFileIndexKey

Signed-off-by: Miguel Molina <miguel@erizocosmi.co>

Author: erizocosmico

commit_files.go

@@ -1,6 +1,7 @@
 package gitbase
 
 import (
+	"bytes"
 	"io"
 
 	"github.com/sirupsen/logrus"
@@ -291,6 +292,71 @@ type commitFileIndexKey struct {
 	Commit     string
 }
 
+func (k *commitFileIndexKey) encode() ([]byte, error) {
+	var buf bytes.Buffer
+	writeString(&buf, k.Repository)
+	if err := writeHash(&buf, k.Packfile); err != nil {
+		return nil, err
+	}
+
+	if err := writeHash(&buf, k.Hash); err != nil {
+		return nil, err
+	}
+
+	writeInt64(&buf, k.Offset)
+	writeString(&buf, k.Name)
+	writeInt64(&buf, k.Mode)
+
+	if err := writeHash(&buf, k.Tree); err != nil {
+		return nil, err
+	}
+
+	if err := writeHash(&buf, k.Commit); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (k *commitFileIndexKey) decode(data []byte) error {
+	var buf = bytes.NewBuffer(data)
+	var err error
+
+	if k.Repository, err = readString(buf); err != nil {
+		return err
+	}
+
+	if k.Packfile, err = readHash(buf); err != nil {
+		return err
+	}
+
+	if k.Hash, err = readHash(buf); err != nil {
+		return err
+	}
+
+	if k.Offset, err = readInt64(buf); err != nil {
+		return err
+	}
+
+	if k.Name, err = readString(buf); err != nil {
+		return err
+	}
+
+	if k.Mode, err = readInt64(buf); err != nil {
+		return err
+	}
+
+	if k.Tree, err = readHash(buf); err != nil {
+		return err
+	}
+
+	if k.Commit, err = readHash(buf); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 type commitFilesKeyValueIter struct {
 	pool    *RepositoryPool
 	repo    *Repository
@@ -369,7 +435,7 @@ func (i *commitFilesKeyValueIter) Next() ([]interface{}, []byte, error) {
 			return nil, nil, err
 		}
 
-		key, err := encodeIndexKey(commitFileIndexKey{
+		key, err := encodeIndexKey(&commitFileIndexKey{
 			Repository: i.repo.ID,
 			Packfile:   packfile.String(),
 			Hash:       f.Blob.Hash.String(),

commit_files_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"gopkg.in/src-d/go-git.v4/plumbing"
 	"gopkg.in/src-d/go-mysql-server.v0/sql"
 	"gopkg.in/src-d/go-mysql-server.v0/sql/expression"
 )
@@ -78,3 +79,26 @@ func TestCommitFilesIndex(t *testing.T) {
 		)},
 	)
 }
+
+func TestEncodeCommitFileIndexKey(t *testing.T) {
+	require := require.New(t)
+
+	k := commitFileIndexKey{
+		Repository: "repo1",
+		Packfile:   plumbing.ZeroHash.String(),
+		Offset:     1234,
+		Hash:       plumbing.ZeroHash.String(),
+		Name:       "foo/bar.md",
+		Mode:       5,
+		Tree:       plumbing.ZeroHash.String(),
+		Commit:     plumbing.ZeroHash.String(),
+	}
+
+	data, err := k.encode()
+	require.NoError(err)
+
+	var k2 commitFileIndexKey
+	require.NoError(k2.decode(data))
+
+	require.Equal(k, k2)
+}

index.go

@@ -2,6 +2,7 @@ package gitbase
 
 import (
 	"bytes"
+	"crypto/sha1"
 	"encoding/binary"
 	"fmt"
 	"io"
@@ -218,6 +219,7 @@ func writeInt64(buf *bytes.Buffer, n int64) {
 	if n < 0 {
 		ux = ^ux
 	}
+
 	var bs = make([]byte, 8)
 	binary.LittleEndian.PutUint64(bs, ux)
 	buf.Write(bs)
@@ -229,19 +231,22 @@ func writeString(buf *bytes.Buffer, s string) {
 	buf.Write(bs)
 }
 
-var errInvalidHashSize = errors.NewKind("invalid hash size: %d, expecting 40 bytes")
+var (
+	hashSize           = 2 * sha1.Size
+	errInvalidHashSize = errors.NewKind("invalid hash size: %d, expecting 40 bytes")
+)
 
 func writeHash(buf *bytes.Buffer, s string) error {
 	bs := []byte(s)
-	if len(bs) != 40 {
+	if len(bs) != hashSize {
 		return errInvalidHashSize.New(len(bs))
 	}
 	buf.Write(bs)
 	return nil
 }
 
 func readHash(buf *bytes.Buffer) (string, error) {
-	bs := make([]byte, 40)
+	bs := make([]byte, hashSize)
 	n, err := io.ReadFull(buf, bs)
 	if err != nil {
 		return "", fmt.Errorf("can't read hash, only read %d: %s", n, err)