Add SetRange command

ds/str/str.go

@@ -25,7 +25,7 @@ func (s *String) Set(v []byte) {
 	s.V = v
 }
 
-// GetSet
+// GetSet set the value and return the old value
 func (s *String) GetSet(v []byte) []byte {
 	old := s.V
 	s.V = v
@@ -217,6 +217,22 @@ func (s *String) Strlen() int64 {
 	return int64(len(s.V))
 }
 
+// SetRange sets the value at the offset
+func (s *String) SetRange(offset int64, data []byte) int64 {
+	if offset < 0 {
+		return 0
+	}
+	vLen := int64(len(s.V))
+	if offset > vLen {
+		s.V = append(s.V, make([]byte, offset-vLen...)...)
+	}
+	if offset+vLen > vLen {
+		s.V = append(s.V, make([]byte, offset+vLen-vLen...)...)
+	}
+	copy(s.V[offset:], data)
+	return int64(len(s.V))
+}
+
 // GetValue the string to bytes
 func (s *String) GetValue() []byte {
 	return s.V

handler.go

@@ -99,6 +99,8 @@ func getCommand(name string) func(n *Nodis, conn *redis.Conn, cmd redis.Command)
 		return getSet
 	case "MGET":
 		return mGet
+	case "SETRANGE":
+		return setRange
 	case "GETRANGE":
 		return getRange
 	case "STRLEN":
@@ -879,6 +881,23 @@ func mGet(n *Nodis, conn *redis.Conn, cmd redis.Command) {
 	})
 }
 
+func setRange(n *Nodis, conn *redis.Conn, cmd redis.Command) {
+	if len(cmd.Args) < 3 {
+		conn.WriteError("SETRANGE requires at least three arguments")
+		return
+	}
+	key := cmd.Args[0]
+	offset, err := strconv.ParseInt(cmd.Args[1], 10, 64)
+	if err != nil {
+		conn.WriteError("ERR offset value is not an integer or out of range")
+		return
+	}
+	value := []byte(cmd.Args[2])
+	execCommand(conn, func() {
+		conn.WriteInteger(n.SetRange(key, offset, value))
+	})
+}
+
 func getRange(n *Nodis, conn *redis.Conn, cmd redis.Command) {
 	if len(cmd.Args) < 3 {
 		conn.WriteError("GETRANGE requires at least three arguments")

str.go

@@ -284,6 +284,19 @@ func (n *Nodis) StrLen(key string) int64 {
 	return v
 }
 
+// SetRange overwrite part of a string at key starting at the specified offset
+func (n *Nodis) SetRange(key string, offset int64, value []byte) int64 {
+	var v int64
+	_ = n.exec(func(tx *Tx) error {
+		meta := tx.writeKey(key, n.newStr)
+		k := meta.ds.(*str.String)
+		v = k.SetRange(offset, value)
+		n.notify(pb.NewOp(pb.OpType_Set, key).Value(k.Get()))
+		return nil
+	})
+	return v
+}
+
 // MSet sets the given keys to their respective values
 func (n *Nodis) MSet(pairs ...string) {
 	if len(pairs)%2 != 0 {