From d529a24e2e0067efb60da1fcc5f1ab61439a9aef Mon Sep 17 00:00:00 2001
From: Daniel Cannon <daniel@danielcannon.co.uk>
Date: Sun, 22 May 2016 22:59:54 +0100
Subject: [PATCH] Changed Connect to return the reason for connections

---
 CHANGELOG.md    |  3 +++
 cluster.go      | 29 +++++++++++++++++++++++++----
 session_test.go |  2 ++
 3 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5714fc8..f5d55fe6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+### Changed
+ - Changed `Connect` to return the reason for connections failing (instead of just "no connections were made when creating the session")
+
 ### Fixed
  - Fixed queries not being retried when using `Query()`, queries are now retried if the request failed due to a bad connection.
  - Fixed `Cursor` methods panicking if using a nil cursor, please note that you should still always check if your queries return an error.
diff --git a/cluster.go b/cluster.go
index 76ae6830..b92f139e 100644
--- a/cluster.go
+++ b/cluster.go
@@ -39,8 +39,12 @@ func NewCluster(hosts []Host, opts *ConnectOpts) (*Cluster, error) {
 		opts:  opts,
 	}
 
-	//Check that hosts in the ClusterConfig is not empty
-	c.connectNodes(c.getSeeds())
+	// Attempt to connect to each host and discover any additional hosts if host
+	// discovery is enabled
+	if err := c.connectNodes(c.getSeeds()); err != nil {
+		return nil, err
+	}
+
 	if !c.IsConnected() {
 		return nil, ErrNoConnectionsStarted
 	}
@@ -206,17 +210,20 @@ func (c *Cluster) listenForNodeChanges() error {
 	return err
 }
 
-func (c *Cluster) connectNodes(hosts []Host) {
+func (c *Cluster) connectNodes(hosts []Host) error {
 	// Add existing nodes to map
 	nodeSet := map[string]*Node{}
 	for _, node := range c.GetNodes() {
 		nodeSet[node.ID] = node
 	}
 
+	var attemptErr error
+
 	// Attempt to connect to each seed host
 	for _, host := range hosts {
 		conn, err := NewConnection(host.String(), c.opts)
 		if err != nil {
+			attemptErr = err
 			Log.Warnf("Error creating connection: %s", err.Error())
 			continue
 		}
@@ -235,6 +242,7 @@ func (c *Cluster) connectNodes(hosts []Host) {
 
 			_, cursor, err := conn.Query(q)
 			if err != nil {
+				attemptErr = err
 				Log.Warnf("Error fetching cluster status: %s", err)
 				continue
 			}
@@ -242,6 +250,7 @@ func (c *Cluster) connectNodes(hosts []Host) {
 			var results []nodeStatus
 			err = cursor.All(&results)
 			if err != nil {
+				attemptErr = err
 				continue
 			}
 
@@ -256,12 +265,14 @@ func (c *Cluster) connectNodes(hosts []Host) {
 						nodeSet[node.ID] = node
 					}
 				} else {
+					attemptErr = err
 					Log.Warnf("Error connecting to node: %s", err)
 				}
 			}
 		} else {
 			svrRsp, err := conn.Server()
 			if err != nil {
+				attemptErr = err
 				Log.Warnf("Error fetching server ID: %s", err)
 				continue
 			}
@@ -273,20 +284,30 @@ func (c *Cluster) connectNodes(hosts []Host) {
 						"id":   node.ID,
 						"host": node.Host.String(),
 					}).Debug("Connected to node")
+
 					nodeSet[node.ID] = node
 				}
 			} else {
+				attemptErr = err
 				Log.Warnf("Error connecting to node: %s", err)
 			}
 		}
 	}
 
+	// If no nodes were contactable then return the last error, this does not
+	// include driver errors such as if there was an issue building the
+	// query
+	if len(nodeSet) == 0 {
+		return attemptErr
+	}
+
 	nodes := []*Node{}
 	for _, node := range nodeSet {
 		nodes = append(nodes, node)
 	}
-
 	c.setNodes(nodes)
+
+	return nil
 }
 
 func (c *Cluster) connectNodeWithStatus(s nodeStatus) (*Node, error) {
diff --git a/session_test.go b/session_test.go
index 53b27de1..01396042 100644
--- a/session_test.go
+++ b/session_test.go
@@ -85,7 +85,9 @@ func (s *RethinkSuite) TestSessionConnectError(c *test.C) {
 		Address: "nonexistanturl",
 		Timeout: time.Second,
 	})
+
 	c.Assert(err, test.NotNil)
+	c.Assert(err, test.FitsTypeOf, RQLConnectionError{})
 }
 
 func (s *RethinkSuite) TestSessionClose(c *test.C) {