webrtc: run onDone callback immediately on close

p2p/transport/webrtc/stream.go

@@ -95,8 +95,8 @@ type stream struct {
 	// SetReadDeadline
 	// See: https://github.com/pion/sctp/pull/290
 	controlMessageReaderEndTime time.Time
-	controlMessageReaderDone    sync.WaitGroup
 
+	onDoneOnce          sync.Once
 	onDone              func()
 	id                  uint16 // for logging purposes
 	dataChannel         *datachannel.DataChannel
@@ -118,8 +118,6 @@ func newStream(
 		dataChannel:       rwc.(*datachannel.DataChannel),
 		onDone:            onDone,
 	}
-	// released when the controlMessageReader goroutine exits
-	s.controlMessageReaderDone.Add(1)
 	s.dataChannel.SetBufferedAmountLowThreshold(bufferedAmountLowThreshold)
 	s.dataChannel.OnBufferedAmountLow(func() {
 		s.notifyWriteStateChanged()
@@ -135,7 +133,7 @@ func (s *stream) Close() error {
 	if isClosed {
 		return nil
 	}
-
+	defer s.cleanup()
 	closeWriteErr := s.CloseWrite()
 	closeReadErr := s.CloseRead()
 	if closeWriteErr != nil || closeReadErr != nil {
@@ -147,10 +145,6 @@ func (s *stream) Close() error {
 	if s.controlMessageReaderEndTime.IsZero() {
 		s.controlMessageReaderEndTime = time.Now().Add(maxFINACKWait)
 		s.setDataChannelReadDeadline(time.Now().Add(-1 * time.Hour))
-		go func() {
-			s.controlMessageReaderDone.Wait()
-			s.cleanup()
-		}()
 	}
 	s.mx.Unlock()
 	return nil
@@ -227,17 +221,10 @@ func (s *stream) spawnControlMessageReader() {
 	s.controlMessageReaderOnce.Do(func() {
 		// Spawn a goroutine to ensure that we're not holding any locks
 		go func() {
-			defer s.controlMessageReaderDone.Done()
 			// cleanup the sctp deadline timer goroutine
 			defer s.setDataChannelReadDeadline(time.Time{})
 
-			setDeadline := func() bool {
-				if s.controlMessageReaderEndTime.IsZero() || time.Now().Before(s.controlMessageReaderEndTime) {
-					s.setDataChannelReadDeadline(s.controlMessageReaderEndTime)
-					return true
-				}
-				return false
-			}
+			defer s.dataChannel.Close()
 
 			// Unblock any Read call waiting on reader.ReadMsg
 			s.setDataChannelReadDeadline(time.Now().Add(-1 * time.Hour))
@@ -256,12 +243,22 @@ func (s *stream) spawnControlMessageReader() {
 				s.processIncomingFlag(s.nextMessage.Flag)
 				s.nextMessage = nil
 			}
-			for s.closeForShutdownErr == nil &&
-				s.sendState != sendStateDataReceived && s.sendState != sendStateReset {
-				var msg pb.Message
-				if !setDeadline() {
+			var msg pb.Message
+			for {
+				// Connection closed. No need to cleanup the data channel.
+				if s.closeForShutdownErr != nil {
+					return
+				}
+				// Write half of the stream completed.
+				if s.sendState == sendStateDataReceived || s.sendState == sendStateReset {
+					return
+				}
+				// FIN_ACK wait deadling exceeded.
+				if !s.controlMessageReaderEndTime.IsZero() && time.Now().After(s.controlMessageReaderEndTime) {
 					return
 				}
+
+				s.setDataChannelReadDeadline(s.controlMessageReaderEndTime)
 				s.mx.Unlock()
 				err := s.reader.ReadMsg(&msg)
 				s.mx.Lock()
@@ -281,12 +278,9 @@ func (s *stream) spawnControlMessageReader() {
 }
 
 func (s *stream) cleanup() {
-	// Even if we close the datachannel pion keeps a reference to the datachannel around.
-	// Remove the onBufferedAmountLow callback to ensure that we at least garbage collect
-	// memory we allocated for this stream.
-	s.dataChannel.OnBufferedAmountLow(nil)
-	s.dataChannel.Close()
-	if s.onDone != nil {
-		s.onDone()
-	}
+	s.onDoneOnce.Do(func() {
+		if s.onDone != nil {
+			s.onDone()
+		}
+	})
 }

p2p/transport/webrtc/stream_test.go

@@ -11,10 +11,12 @@ import (
 
 	"github.com/libp2p/go-libp2p/p2p/transport/webrtc/pb"
 	"github.com/libp2p/go-msgio/pbio"
+	"google.golang.org/protobuf/proto"
 
 	"github.com/libp2p/go-libp2p/core/network"
 
 	"github.com/pion/datachannel"
+	"github.com/pion/sctp"
 	"github.com/pion/webrtc/v3"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -98,6 +100,44 @@ func getDetachedDataChannels(t *testing.T) (detachedChan, detachedChan) {
 	return <-answerChan, <-offerRWCChan
 }
 
+func checkDataChannelOpen(t *testing.T, dc *datachannel.DataChannel) {
+	buf := make([]byte, 0)
+	dc.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
+	for {
+		_, err := dc.Read(buf)
+		if errors.Is(err, os.ErrDeadlineExceeded) {
+			break
+		}
+		if !errors.Is(err, io.ErrShortBuffer) {
+			t.Fatal("unexpected err", err)
+		}
+	}
+}
+
+// checkDataChannelClosed checks if the datachannel has been closed.
+// It sends empty messages on the data channel to check if the channel has been closed.
+// The control message reader goroutine depends on exclusive access to datachannel.Read
+// so we have to depend on Write to determine whether the channel has been closed.
+func checkDataChannelClosed(t *testing.T, dc *datachannel.DataChannel) {
+	t.Helper()
+	emptyMsg := &pb.Message{}
+	msg, err := proto.Marshal(emptyMsg)
+	if err != nil {
+		t.Fatal("unexpected mashalling error", err)
+	}
+	for i := 0; i < 5; i++ {
+		_, err := dc.Write(msg)
+		if err != nil {
+			if errors.Is(err, sctp.ErrStreamClosed) {
+				return
+			} else {
+				t.Fatal("unexpected write err: ", err)
+			}
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+}
+
 func TestStreamSimpleReadWriteClose(t *testing.T) {
 	client, server := getDetachedDataChannels(t)
 
@@ -357,27 +397,22 @@ func TestStreamCloseAfterFINACK(t *testing.T) {
 	serverStr := newStream(server.dc, server.rwc, func() {})
 
 	go func() {
-		done <- true
 		err := clientStr.Close()
 		assert.NoError(t, err)
 	}()
-	<-done
 
 	select {
 	case <-done:
-		t.Fatalf("Close should not have completed without processing FIN_ACK")
 	case <-time.After(200 * time.Millisecond):
+		t.Fatalf("Close should signal OnDone immediately")
 	}
 
+	// Reading FIN_ACK on server should trigger data channel close on the client
 	b := make([]byte, 1)
 	_, err := serverStr.Read(b)
 	require.Error(t, err)
 	require.ErrorIs(t, err, io.EOF)
-	select {
-	case <-done:
-	case <-time.After(3 * time.Second):
-		t.Errorf("Close should have completed")
-	}
+	checkDataChannelClosed(t, client.rwc.(*datachannel.DataChannel))
 }
 
 // TestStreamFinAckAfterStopSending tests that FIN_ACK is sent even after the write half
@@ -400,8 +435,8 @@ func TestStreamFinAckAfterStopSending(t *testing.T) {
 
 	select {
 	case <-done:
-		t.Errorf("Close should not have completed without processing FIN_ACK")
 	case <-time.After(500 * time.Millisecond):
+		t.Errorf("Close should signal onDone immediately")
 	}
 
 	// serverStr has write half closed and read half open
@@ -410,11 +445,8 @@ func TestStreamFinAckAfterStopSending(t *testing.T) {
 	_, err := serverStr.Read(b)
 	require.NoError(t, err)
 	serverStr.Close() // Sends stop_sending, fin
-	select {
-	case <-done:
-	case <-time.After(5 * time.Second):
-		t.Fatalf("Close should have completed")
-	}
+	checkDataChannelClosed(t, server.rwc.(*datachannel.DataChannel))
+	checkDataChannelClosed(t, client.rwc.(*datachannel.DataChannel))
 }
 
 func TestStreamConcurrentClose(t *testing.T) {
@@ -446,26 +478,35 @@ func TestStreamConcurrentClose(t *testing.T) {
 	case <-time.After(2 * time.Second):
 		t.Fatalf("concurrent close should succeed quickly")
 	}
+
+	// Wait for FIN_ACK AND datachannel close
+	checkDataChannelClosed(t, client.rwc.(*datachannel.DataChannel))
+	checkDataChannelClosed(t, server.rwc.(*datachannel.DataChannel))
+
 }
 
 func TestStreamResetAfterClose(t *testing.T) {
-	client, _ := getDetachedDataChannels(t)
+	client, server := getDetachedDataChannels(t)
 
 	done := make(chan bool, 2)
 	clientStr := newStream(client.dc, client.rwc, func() { done <- true })
 	clientStr.Close()
 
 	select {
 	case <-done:
-		t.Fatalf("Close shouldn't run cleanup immediately")
 	case <-time.After(500 * time.Millisecond):
+		t.Fatalf("Close should run cleanup immediately")
 	}
-
+	// The server data channel should still be open
+	checkDataChannelOpen(t, server.rwc.(*datachannel.DataChannel))
 	clientStr.Reset()
+	// Reset closes the datachannels
+	checkDataChannelClosed(t, server.rwc.(*datachannel.DataChannel))
+	checkDataChannelClosed(t, client.rwc.(*datachannel.DataChannel))
 	select {
 	case <-done:
-	case <-time.After(2 * time.Second):
-		t.Fatalf("Reset should run callback immediately")
+		t.Fatalf("onDone should not be called twice")
+	case <-time.After(50 * time.Millisecond):
 	}
 }
 
@@ -478,30 +519,18 @@ func TestStreamDataChannelCloseOnFINACK(t *testing.T) {
 	clientStr.Close()
 
 	select {
-	case <-done:
-		t.Fatalf("Close shouldn't run cleanup immediately")
 	case <-time.After(500 * time.Millisecond):
+		t.Fatalf("Close should run cleanup immediately")
+	case <-done:
 	}
 
+	// sending FIN_ACK closes the datachannel
 	serverWriter := pbio.NewDelimitedWriter(server.rwc)
 	err := serverWriter.WriteMsg(&pb.Message{Flag: pb.Message_FIN_ACK.Enum()})
 	require.NoError(t, err)
-	select {
-	case <-done:
-	case <-time.After(2 * time.Second):
-		t.Fatalf("Callback should be run on reading FIN_ACK")
-	}
-	b := make([]byte, 100)
-	N := 0
-	for {
-		n, err := server.rwc.Read(b)
-		N += n
-		if err != nil {
-			require.ErrorIs(t, err, io.EOF)
-			break
-		}
-	}
-	require.Less(t, N, 10)
+
+	checkDataChannelClosed(t, server.rwc.(*datachannel.DataChannel))
+	checkDataChannelClosed(t, client.rwc.(*datachannel.DataChannel))
 }
 
 func TestStreamChunking(t *testing.T) {

p2p/transport/webrtc/stream_write.go

@@ -129,11 +129,10 @@ func (s *stream) cancelWrite() error {
 		return nil
 	}
 	s.sendState = sendStateReset
+	// Remove reference to this stream from data channel
+	s.dataChannel.OnBufferedAmountLow(nil)
 	s.notifyWriteStateChanged()
-	if err := s.writer.WriteMsg(&pb.Message{Flag: pb.Message_RESET.Enum()}); err != nil {
-		return err
-	}
-	return nil
+	return s.writer.WriteMsg(&pb.Message{Flag: pb.Message_RESET.Enum()})
 }
 
 func (s *stream) CloseWrite() error {
@@ -144,11 +143,10 @@ func (s *stream) CloseWrite() error {
 		return nil
 	}
 	s.sendState = sendStateDataSent
+	// Remove reference to this stream from data channel
+	s.dataChannel.OnBufferedAmountLow(nil)
 	s.notifyWriteStateChanged()
-	if err := s.writer.WriteMsg(&pb.Message{Flag: pb.Message_FIN.Enum()}); err != nil {
-		return err
-	}
-	return nil
+	return s.writer.WriteMsg(&pb.Message{Flag: pb.Message_FIN.Enum()})
 }
 
 func (s *stream) notifyWriteStateChanged() {