Added TOUCH support

memcache/memcache.go

@@ -105,6 +105,7 @@ var (
 	resultNotFound  = []byte("NOT_FOUND\r\n")
 	resultDeleted   = []byte("DELETED\r\n")
 	resultEnd       = []byte("END\r\n")
+	resultTouched	= []byte("TOUCHED\r\n")
 
 	resultClientErrorPrefix = []byte("CLIENT_ERROR ")
 )
@@ -178,7 +179,7 @@ func (cn *conn) extendDeadline() {
 }
 
 // condRelease releases this connection if the error pointed to by err
-// is is nil (not an error) or is only a protocol level error (e.g. a
+// is nil (not an error) or is only a protocol level error (e.g. a
 // cache miss).  The purpose is to not recycle TCP connections that
 // are bad.
 func (cn *conn) condRelease(err *error) {
@@ -310,6 +311,12 @@ func (c *Client) Get(key string) (item *Item, err error) {
 	return
 }
 
+func (c *Client) Touch(key string, seconds int32) (err error) {
+	return c.withKeyAddr(key, func(addr net.Addr) error {
+		return c.touchFromAddr(addr, []string{key}, seconds)
+	}) 
+}
+
 func (c *Client) withKeyAddr(key string, fn func(net.Addr) error) (err error) {
 	if !legalKey(key) {
 		return ErrMalformedKey
@@ -351,6 +358,32 @@ func (c *Client) getFromAddr(addr net.Addr, keys []string, cb func(*Item)) error
 	})
 }
 
+func (c *Client) touchFromAddr(addr net.Addr, keys []string, expiration int32) error {
+	return c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
+		for _, key := range keys {
+			if _, err := fmt.Fprintf(rw, "touch %s %d\r\n", key, expiration); err != nil {
+				return err
+			}
+			if err := rw.Flush(); err != nil {
+				return err
+			}
+			line, err := rw.ReadSlice('\n')
+			if err != nil {
+				return err
+			}
+			switch {
+			case bytes.Equal(line, resultTouched):
+				break
+			case bytes.Equal(line, resultNotFound):
+				return ErrCacheMiss
+			default:
+				return fmt.Errorf("memcache: unexpected response line from touch: %q", string(line))
+			}
+		}
+		return nil
+	})
+}
+
 // GetMulti is a batch version of Get. The returned map from keys to
 // items may have fewer elements than the input slice, due to memcache
 // cache misses. Each key must be at most 250 bytes in length.