Retry control connection setup if getting of peers fails

This could help with long startup times in case of issues
when fetching peer host info.

control.go

@@ -244,9 +244,9 @@ func (c *controlConn) discoverProtocol(hosts []*HostInfo) (int, error) {
 	return 0, err
 }
 
-func (c *controlConn) connect(hosts []*HostInfo) error {
+func (c *controlConn) connect(hosts []*HostInfo) (newHosts []*HostInfo, partitionerName string, errOut error) {
 	if len(hosts) == 0 {
-		return errors.New("control: no endpoints specified")
+		return hosts, "", errors.New("control: no endpoints specified")
 	}
 
 	// shuffle endpoints so not all drivers will connect to the same initial
@@ -264,31 +264,59 @@ func (c *controlConn) connect(hosts []*HostInfo) error {
 			c.session.logger.Printf("gocql: unable to dial control conn %v:%v: %v\n", host.ConnectAddress(), host.Port(), err)
 			continue
 		}
-		err = c.setupConn(conn)
+
+		newHosts, partitionerName, err = c.connectSetupConn(conn, hosts)
 		if err == nil {
 			break
 		}
-		c.session.logger.Printf("gocql: unable setup control conn %v:%v: %v\n", host.ConnectAddress(), host.Port(), err)
+		err = fmt.Errorf("%v:%v: %v", host.ConnectAddress(), host.Port(), err)
+		c.session.logger.Printf("gocql: unable setup control conn %v\n", err)
 		conn.Close()
 		conn = nil
 	}
 	if conn == nil {
-		return fmt.Errorf("unable to connect to initial hosts: %v", err)
+		return hosts, "", fmt.Errorf("unable to connect to initial hosts: %v", err)
 	}
 
 	// we could fetch the initial ring here and update initial host data. So that
 	// when we return from here we have a ring topology ready to go.
 
 	go c.heartBeat()
 
-	return nil
+	return newHosts, partitionerName, nil
 }
 
 type connHost struct {
 	conn *Conn
 	host *HostInfo
 }
 
+func (c *controlConn) connectSetupConn(conn *Conn, hosts []*HostInfo,
+) (newHosts []*HostInfo, partitionerName string, errOut error) {
+	err := c.setupConn(conn)
+	if err != nil {
+		return hosts, "", err
+	}
+
+	if c.session.cfg.DisableInitialHostLookup {
+		return hosts, "", nil
+	}
+
+	allHosts, partitionerName, err := c.session.hostSource.GetHosts()
+	if err != nil {
+		return hosts, "", err
+	}
+	c.session.policy.SetPartitioner(partitionerName)
+	filteredHosts := make([]*HostInfo, 0, len(allHosts))
+	for _, host := range allHosts {
+		if !c.session.cfg.filterHost(host) {
+			filteredHosts = append(filteredHosts, host)
+		}
+	}
+
+	return filteredHosts, partitionerName, nil
+}
+
 func (c *controlConn) setupConn(conn *Conn) error {
 	// we need up-to-date host info for the filterHost call below
 	iter := conn.querySystemLocal(context.TODO())
@@ -322,6 +350,7 @@ func (c *controlConn) setupConn(conn *Conn) error {
 		// TODO(martin-sucha): Trigger pool refill for all hosts, like in reconnectDownedHosts?
 		go c.session.startPoolFill(host)
 	}
+
 	return nil
 }