Update dependencies (#886)

vendor/github.com/nlopes/slack/websocket.go

@@ -2,7 +2,6 @@ package slack
 
 import (
 	"encoding/json"
-	"errors"
 	"net/url"
 	"sync"
 	"time"
@@ -33,11 +32,10 @@ type RTM struct {
 	IncomingEvents   chan RTMEvent
 	outgoingMessages chan OutgoingMessage
 	killChannel      chan bool
-	disconnected     chan struct{} // disconnected is closed when Disconnect is invoked, regardless of connection state. Allows for ManagedConnection to not leak.
+	disconnected     chan struct{}
+	disconnectedm    *sync.Once
 	forcePing        chan bool
 	rawEvents        chan json.RawMessage
-	wasIntentional   bool
-	isConnected      bool
 
 	// UserDetails upon connection
 	info *Info
@@ -58,32 +56,30 @@ type RTM struct {
 	connParams url.Values
 }
 
+// signal that we are disconnected by closing the channel.
+// protect it with a mutex to ensure it only happens once.
+func (rtm *RTM) disconnect() {
+	rtm.disconnectedm.Do(func() {
+		close(rtm.disconnected)
+	})
+}
+
 // Disconnect and wait, blocking until a successful disconnection.
 func (rtm *RTM) Disconnect() error {
-	// avoid RTM disconnect race conditions
-	rtm.mu.Lock()
-	defer rtm.mu.Unlock()
-
-	// always push into the disconnected channel when invoked,
+	// always push into the kill channel when invoked,
 	// this lets the ManagedConnection() function properly clean up.
 	// if the buffer is full then just continue on.
 	select {
-	case rtm.disconnected <- struct{}{}:
-	default:
+	case rtm.killChannel <- true:
+		return nil
+	case <-rtm.disconnected:
+		return ErrAlreadyDisconnected
 	}
-
-	if !rtm.isConnected {
-		return errors.New("Invalid call to Disconnect - Slack API is already disconnected")
-	}
-
-	rtm.killChannel <- true
-	return nil
 }
 
 // GetInfo returns the info structure received when calling
-// "startrtm", holding all channels, groups and other metadata needed
-// to implement a full chat client. It will be non-nil after a call to
-// StartRTM().
+// "startrtm", holding metadata needed to implement a full
+// chat client. It will be non-nil after a call to StartRTM().
 func (rtm *RTM) GetInfo() *Info {
 	return rtm.info
 }