support multi transaction

interface/redis/client.go

@@ -5,9 +5,17 @@ type Connection interface {
 	Write([]byte) error
 	SetPassword(string)
 	GetPassword() string
+
 	// client should keep its subscribing channels
 	Subscribe(channel string)
 	UnSubscribe(channel string)
 	SubsCount() int
 	GetChannels() []string
+
+	// used for `Multi` command
+	InMultiState() bool
+	SetMultiState(bool)
+	GetQueuedCmdLine() [][][]byte
+	EnqueueCmd([][]byte)
+	ClearQueuedCmds()
 }