snap: expose GetDBFilePathByID() as a class function

snap/db.go

@@ -15,6 +15,7 @@
 package snap
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -24,6 +25,8 @@ import (
 	"github.com/coreos/etcd/pkg/fileutil"
 )
 
+var ErrDBSnapFileNotFound = errors.New("snap: db snapshot file doesn't exist")
+
 // SaveDBFrom saves snapshot of the database from the given reader. It
 // guarantees the save operation is atomic.
 func (s *Snapshotter) SaveDBFrom(r io.Reader, id uint64) (int64, error) {
@@ -52,23 +55,26 @@ func (s *Snapshotter) SaveDBFrom(r io.Reader, id uint64) (int64, error) {
 		return n, err
 	}
 
-	plog.Infof("saved database snapshot to disk [total bytes: %d]", n)
-
+	plog.Infof("saved database snapshot %s to disk [total bytes: %d]", fn, n)
 	return n, nil
 }
 
 // DBFilePath returns the file path for the snapshot of the database with
 // given id. If the snapshot does not exist, it returns error.
 func (s *Snapshotter) DBFilePath(id uint64) (string, error) {
-	fns, err := fileutil.ReadDir(s.dir)
+	return GetDBFilePathByID(s.dir, id)
+}
+
+func GetDBFilePathByID(snapDir string, id uint64) (string, error) {
+	fns, err := fileutil.ReadDir(snapDir)
 	if err != nil {
 		return "", err
 	}
 	wfn := fmt.Sprintf("%016x.snap.db", id)
 	for _, fn := range fns {
 		if fn == wfn {
-			return filepath.Join(s.dir, fn), nil
+			return filepath.Join(snapDir, fn), nil
 		}
 	}
-	return "", fmt.Errorf("snap: snapshot file doesn't exist")
+	return "", ErrDBSnapFileNotFound
 }