fix: handle case where swarm closes before stream

When we close a connection, we set the "stream" set to nil to avoid opening new
stream. Unfortunately, this meant we wouldn't decrement the reference count on
the swarm.

swarm_conn.go

@@ -87,12 +87,10 @@ func (c *Conn) doClose() {
 	}()
 }
 
-func (c *Conn) removeStream(s *Stream) bool {
+func (c *Conn) removeStream(s *Stream) {
 	c.streams.Lock()
-	_, has := c.streams.m[s]
 	delete(c.streams.m, s)
 	c.streams.Unlock()
-	return has
 }
 
 // listens for new streams.

swarm_stream.go

@@ -22,6 +22,8 @@ type Stream struct {
 	stream mux.MuxedStream
 	conn   *Conn
 
+	closeOnce sync.Once
+
 	notifyLk sync.Mutex
 
 	protocol atomic.Value
@@ -76,15 +78,15 @@ func (s *Stream) Write(p []byte) (int, error) {
 // resources.
 func (s *Stream) Close() error {
 	err := s.stream.Close()
-	s.remove()
+	s.closeOnce.Do(s.remove)
 	return err
 }
 
 // Reset resets the stream, signaling an error on both ends and freeing all
 // associated resources.
 func (s *Stream) Reset() error {
 	err := s.stream.Reset()
-	s.remove()
+	s.closeOnce.Do(s.remove)
 	return err
 }
 
@@ -102,9 +104,7 @@ func (s *Stream) CloseRead() error {
 }
 
 func (s *Stream) remove() {
-	if !s.conn.removeStream(s) {
-		return
-	}
+	s.conn.removeStream(s)
 
 	// We *must* do this in a goroutine. This can be called during a
 	// an open notification and will block until that notification is done.

swarm_test.go

@@ -440,3 +440,20 @@ func TestNoDial(t *testing.T) {
 		t.Fatal("should have failed with ErrNoConn")
 	}
 }
+
+func TestCloseWithOpenStreams(t *testing.T) {
+	ctx := context.Background()
+	swarms := makeSwarms(ctx, t, 2)
+	connectSwarms(t, ctx, swarms)
+
+	s, err := swarms[0].NewStream(ctx, swarms[1].LocalPeer())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer s.Close()
+	// close swarm before stream.
+	err = swarms[0].Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+}