Merge pull request #4539 from xiang90/snap

*: record the number of bytes of snapshot sent/received

etcdserver/snapshot_merge.go

@@ -60,7 +60,10 @@ func (s *EtcdServer) createMergedSnapshotMessage(m raftpb.Message, snapi uint64,
 func newSnapshotReaderCloser(snapshot backend.Snapshot) io.ReadCloser {
 	pr, pw := io.Pipe()
 	go func() {
-		_, err := snapshot.WriteTo(pw)
+		n, err := snapshot.WriteTo(pw)
+		if err == nil {
+			plog.Infof("wrote database snapshot out [total bytes: %d]", n)
+		}
 		pw.CloseWithError(err)
 		snapshot.Close()
 	}()

snap/db.go

@@ -31,7 +31,8 @@ func (s *Snapshotter) SaveDBFrom(r io.Reader, id uint64) error {
 	if err != nil {
 		return err
 	}
-	_, err = io.Copy(f, r)
+	var n int64
+	n, err = io.Copy(f, r)
 	if err == nil {
 		err = f.Sync()
 	}
@@ -50,6 +51,9 @@ func (s *Snapshotter) SaveDBFrom(r io.Reader, id uint64) error {
 		os.Remove(f.Name())
 		return err
 	}
+
+	plog.Infof("saved database snapshot to disk [total bytes: %d]", n)
+
 	return nil
 }