From dfa93436c24f6f9e8d9d52746b06587650d34cec Mon Sep 17 00:00:00 2001
From: David Wragg <david@wragg.org>
Date: Fri, 22 May 2015 11:26:30 +0100
Subject: [PATCH] Fix use of "break" within "select" in LocalConnection
 actorLoop

From the golang spec: 'A "break" statement terminates execution of the
innermost "for", "switch", or "select" statement within the same
function.'  But the LocalConnection actorLoop seems to assume it
skips the "select" and terminates the enclosing "for".

As a result, if something did conn.Shutdown(nil), it would not actually
shutdown the connection. It turns out this is never a problem, because
Shutdown is always called with a non-nil error, even though there is code
in a few places to handle the nil case. By cleaning that up, the dubious
"break" is eliminated.
---
 router/connection.go | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/router/connection.go b/router/connection.go
index 7e380730..2baa2233 100644
--- a/router/connection.go
+++ b/router/connection.go
@@ -196,13 +196,14 @@ func (conn *LocalConnection) SendProtocolMsg(m ProtocolMsg) {
 
 // Async
 func (conn *LocalConnection) Shutdown(err error) {
+	// err should always be a real error, even if only io.EOF
+	if err == nil {
+		panic("nil error")
+	}
+
 	// Run on its own goroutine in case the channel is backed up
 	go func() {
-		if err == nil {
-			conn.sendAction(nil)
-		} else {
-			conn.sendAction(func() error { return err })
-		}
+		conn.sendAction(func() error { return err })
 	}()
 }
 
@@ -379,9 +380,6 @@ func (conn *LocalConnection) actorLoop(actionChan <-chan ConnectionAction) (err
 	for err == nil {
 		select {
 		case action := <-actionChan:
-			if action == nil {
-				break
-			}
 			err = action()
 		case <-conn.heartbeatTCP.C:
 			err = conn.sendSimpleProtocolMsg(ProtocolHeartbeat)
@@ -398,13 +396,10 @@ func (conn *LocalConnection) actorLoop(actionChan <-chan ConnectionAction) (err
 }
 
 func (conn *LocalConnection) shutdown(err error) {
-	switch {
-	case err != nil && conn.remote == nil:
+	if conn.remote == nil {
 		log.Printf("->[%s] connection shutting down due to error during handshake: %v\n", conn.remoteTCPAddr, err)
-	case err != nil:
+	} else {
 		conn.Log("connection shutting down due to error:", err)
-	default:
-		conn.Log("connection shutting down")
 	}
 
 	if conn.TCPConn != nil {