Bump queue-worker and NATS

NATS moved its primary library to: github.com/nats-io/stan.go

This commit synchronises the library in the gateway to match the
queue worker.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

gateway/vendor/github.com/nats-io/nats.go/netchan.go

@@ -0,0 +1,111 @@
+// Copyright 2013-2018 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package nats
+
+import (
+	"errors"
+	"reflect"
+)
+
+// This allows the functionality for network channels by binding send and receive Go chans
+// to subjects and optionally queue groups.
+// Data will be encoded and decoded via the EncodedConn and its associated encoders.
+
+// BindSendChan binds a channel for send operations to NATS.
+func (c *EncodedConn) BindSendChan(subject string, channel interface{}) error {
+	chVal := reflect.ValueOf(channel)
+	if chVal.Kind() != reflect.Chan {
+		return ErrChanArg
+	}
+	go chPublish(c, chVal, subject)
+	return nil
+}
+
+// Publish all values that arrive on the channel until it is closed or we
+// encounter an error.
+func chPublish(c *EncodedConn, chVal reflect.Value, subject string) {
+	for {
+		val, ok := chVal.Recv()
+		if !ok {
+			// Channel has most likely been closed.
+			return
+		}
+		if e := c.Publish(subject, val.Interface()); e != nil {
+			// Do this under lock.
+			c.Conn.mu.Lock()
+			defer c.Conn.mu.Unlock()
+
+			if c.Conn.Opts.AsyncErrorCB != nil {
+				// FIXME(dlc) - Not sure this is the right thing to do.
+				// FIXME(ivan) - If the connection is not yet closed, try to schedule the callback
+				if c.Conn.isClosed() {
+					go c.Conn.Opts.AsyncErrorCB(c.Conn, nil, e)
+				} else {
+					c.Conn.ach.push(func() { c.Conn.Opts.AsyncErrorCB(c.Conn, nil, e) })
+				}
+			}
+			return
+		}
+	}
+}
+
+// BindRecvChan binds a channel for receive operations from NATS.
+func (c *EncodedConn) BindRecvChan(subject string, channel interface{}) (*Subscription, error) {
+	return c.bindRecvChan(subject, _EMPTY_, channel)
+}
+
+// BindRecvQueueChan binds a channel for queue-based receive operations from NATS.
+func (c *EncodedConn) BindRecvQueueChan(subject, queue string, channel interface{}) (*Subscription, error) {
+	return c.bindRecvChan(subject, queue, channel)
+}
+
+// Internal function to bind receive operations for a channel.
+func (c *EncodedConn) bindRecvChan(subject, queue string, channel interface{}) (*Subscription, error) {
+	chVal := reflect.ValueOf(channel)
+	if chVal.Kind() != reflect.Chan {
+		return nil, ErrChanArg
+	}
+	argType := chVal.Type().Elem()
+
+	cb := func(m *Msg) {
+		var oPtr reflect.Value
+		if argType.Kind() != reflect.Ptr {
+			oPtr = reflect.New(argType)
+		} else {
+			oPtr = reflect.New(argType.Elem())
+		}
+		if err := c.Enc.Decode(m.Subject, m.Data, oPtr.Interface()); err != nil {
+			c.Conn.err = errors.New("nats: Got an error trying to unmarshal: " + err.Error())
+			if c.Conn.Opts.AsyncErrorCB != nil {
+				c.Conn.ach.push(func() { c.Conn.Opts.AsyncErrorCB(c.Conn, m.Sub, c.Conn.err) })
+			}
+			return
+		}
+		if argType.Kind() != reflect.Ptr {
+			oPtr = reflect.Indirect(oPtr)
+		}
+		// This is a bit hacky, but in this instance we may be trying to send to a closed channel.
+		// and the user does not know when it is safe to close the channel.
+		defer func() {
+			// If we have panicked, recover and close the subscription.
+			if r := recover(); r != nil {
+				m.Sub.Unsubscribe()
+			}
+		}()
+		// Actually do the send to the channel.
+		chVal.Send(oPtr)
+	}
+
+	return c.Conn.subscribe(subject, queue, cb, nil, false)
+}