Merge pull request #7 from yunify/refine_test_connection

refine test connection logic

LICENSE

@@ -17,3 +17,23 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+Copyright (c) 2018 Yunify
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

backends/metad/client.go

@@ -26,20 +26,6 @@ type Connection struct {
 	errTimes   uint32
 }
 
-func (c *Connection) testConnection() error {
-	var err error
-	maxTime := 15 * time.Second
-
-	for i := 1 * time.Second; i < maxTime; i *= time.Duration(2) {
-		if _, err = c.makeMetaDataRequest("/"); err == nil {
-			return nil // OK
-		}
-
-		time.Sleep(i)
-	}
-	return err
-}
-
 func (c *Connection) makeMetaDataRequest(path string) ([]byte, error) {
 	req, err := http.NewRequest("GET", strings.Join([]string{c.url, path}, ""), nil)
 	if err != nil {
@@ -98,6 +84,27 @@ func NewMetadClient(backendNodes []string) (*Client, error) {
 }
 
 func (c *Client) selectConnection() error {
+	maxTime := 15 * time.Second
+	i := 1 * time.Second
+	for ; i < maxTime; i *= time.Duration(2) {
+		if conn, err := c.testConnection(); err == nil {
+			//found available conn
+			if c.current != nil {
+				atomic.StoreUint32(&c.current.errTimes, 0)
+			}
+			c.current = conn
+			break
+		}
+		time.Sleep(i)
+	}
+	if i >= maxTime {
+		return fmt.Errorf("fail to connect any backend.")
+	}
+	log.Info("Using Metad URL: " + c.current.url)
+	return nil
+}
+
+func (c *Client) testConnection() (*Connection, error) {
 	//random start
 	if c.current == nil {
 		rand.Seed(time.Now().Unix())
@@ -107,22 +114,17 @@ func (c *Client) selectConnection() error {
 	c.connections = c.connections.Next()
 	conn := c.connections.Value.(*Connection)
 	startConn := conn
-	err := conn.testConnection()
+	_, err := conn.makeMetaDataRequest("/")
 	for err != nil {
-		log.Error("Connection to [%s], error: [%s]", conn.url, err.Error())
+		log.Error("connection to [%s], error: [%v]", conn.url, err)
 		c.connections = c.connections.Next()
 		conn = c.connections.Value.(*Connection)
 		if conn == startConn {
-			return errors.New("Fail to connect any backend.")
+			break
 		}
-		err = conn.testConnection()
-	}
-	if c.current != nil {
-		atomic.StoreUint32(&c.current.errTimes, 0)
+		_, err = conn.makeMetaDataRequest("/")
 	}
-	c.current = conn
-	log.Info("Using Metad URL: " + c.current.url)
-	return nil
+	return conn, err
 }
 
 func (c *Client) GetValues(keys []string) (map[string]string, error) {