Add idle timeout into session manager

pkg/client/client.go

@@ -335,6 +335,10 @@ func (client *Client) ServerVersion() string {
 }
 
 func (client *Client) query(query string, args ...interface{}) (*Result, error) {
+	if client.db == nil {
+		return nil, nil
+	}
+
 	// Update the last usage time
 	defer func() {
 		client.lastQueryTime = time.Now().UTC()
@@ -366,7 +370,7 @@ func (client *Client) query(query string, args ...interface{}) (*Result, error)
 		result := Result{
 			Columns: []string{"Rows Affected"},
 			Rows: []Row{
-				Row{affected},
+				{affected},
 			},
 		}
 
@@ -446,6 +450,10 @@ func (c *Client) IsClosed() bool {
 	return c.closed
 }
 
+func (c *Client) LastQueryTime() time.Time {
+	return c.lastQueryTime
+}
+
 func (client *Client) IsIdle() bool {
 	mins := int(time.Since(client.lastQueryTime).Minutes())