Add support for watch in transactions.

commands.go

@@ -1,6 +1,7 @@
 package redis
 
 import (
+	"fmt"
 	"strconv"
 )
 
@@ -857,11 +858,123 @@ func (c *Client) Publish(channel, message string) *IntReq {
 
 //------------------------------------------------------------------------------
 
-func (c *Client) Multi() *Client {
+func (c *Client) PipelineClient() (*Client, error) {
 	return &Client{
 		ConnPool: c.ConnPool,
 		InitConn: c.InitConn,
-
-		reqs: make([]Req, 0),
-	}
+		reqs:     make([]Req, 0),
+	}, nil
+}
+
+//------------------------------------------------------------------------------
+
+func (c *Client) MultiClient() (*Client, error) {
+	return &Client{
+		ConnPool: NewSingleConnPool(c.ConnPool),
+		InitConn: c.InitConn,
+	}, nil
+}
+
+func (c *Client) Multi() {
+	c.reqs = make([]Req, 0)
+}
+
+func (c *Client) Watch(keys ...string) *StatusReq {
+	args := append([]string{"WATCH"}, keys...)
+	req := NewStatusReq(args...)
+	c.Process(req)
+	return req
+}
+
+func (c *Client) Unwatch(keys ...string) *StatusReq {
+	args := append([]string{"UNWATCH"}, keys...)
+	req := NewStatusReq(args...)
+	c.Process(req)
+	return req
+}
+
+func (c *Client) Discard() {
+	c.mtx.Lock()
+	c.reqs = c.reqs[:0]
+	c.mtx.Unlock()
+}
+
+func (c *Client) Exec() ([]Req, error) {
+	c.mtx.Lock()
+	if len(c.reqs) == 0 {
+		c.mtx.Unlock()
+		return c.reqs, nil
+	}
+	reqs := c.reqs
+	c.reqs = nil
+	c.mtx.Unlock()
+
+	conn, err := c.conn()
+	if err != nil {
+		return nil, err
+	}
+
+	err = c.ExecReqs(reqs, conn)
+	if err != nil {
+		c.ConnPool.Remove(conn)
+		return nil, err
+	}
+
+	c.ConnPool.Add(conn)
+	return reqs, nil
+}
+
+func (c *Client) ExecReqs(reqs []Req, conn *Conn) error {
+	multiReq := make([]byte, 0, 1024)
+	multiReq = append(multiReq, PackReq([]string{"MULTI"})...)
+	for _, req := range reqs {
+		multiReq = append(multiReq, req.Req()...)
+	}
+	multiReq = append(multiReq, PackReq([]string{"EXEC"})...)
+
+	err := c.WriteReq(multiReq, conn)
+	if err != nil {
+		return err
+	}
+
+	statusReq := NewStatusReq()
+
+	// Parse MULTI command reply.
+	_, err = statusReq.ParseReply(conn.Rd)
+	if err != nil {
+		return err
+	}
+
+	// Parse queued replies.
+	for _ = range reqs {
+		_, err = statusReq.ParseReply(conn.Rd)
+		if err != nil {
+			return err
+		}
+	}
+
+	// Parse number of replies.
+	line, err := readLine(conn.Rd)
+	if err != nil {
+		return err
+	}
+	if line[0] != '*' {
+		return fmt.Errorf("Expected '*', but got line %q", line)
+	}
+	if isNilReplies(line) {
+		return Nil
+	}
+
+	// Parse replies.
+	for i := 0; i < len(reqs); i++ {
+		req := reqs[i]
+		val, err := req.ParseReply(conn.Rd)
+		if err != nil {
+			req.SetErr(err)
+		} else {
+			req.SetVal(val)
+		}
+	}
+
+	return nil
 }