optimize window update generation, reducing profiler footprint by 8%

flowcontrol/flow_control_manager.go

@@ -106,25 +106,15 @@ func (f *flowControlManager) AddBytesRead(streamID protocol.StreamID, n protocol
 	return nil
 }
 
-// streamID must not be 0 here
+func (f *flowControlManager) GetWindowUpdates() (res []WindowUpdate) {
-func (f *flowControlManager) MaybeTriggerStreamWindowUpdate(streamID protocol.StreamID) (bool, protocol.ByteCount, error) {
 	f.mutex.Lock()
 	defer f.mutex.Unlock()
-
+	for id, fc := range f.streamFlowController {
-	streamFlowController, err := f.getFlowController(streamID)
+		if necessary, offset := fc.MaybeTriggerWindowUpdate(); necessary {
-	if err != nil {
+			res = append(res, WindowUpdate{StreamID: id, Offset: offset})
-		return false, 0, err
 		}
-
+	}
-	doIt, offset := streamFlowController.MaybeTriggerWindowUpdate()
+	return res
-	return doIt, offset, nil
-}
-
-func (f *flowControlManager) MaybeTriggerConnectionWindowUpdate() (bool, protocol.ByteCount) {
-	f.mutex.Lock()
-	defer f.mutex.Unlock()
-
-	return f.streamFlowController[0].MaybeTriggerWindowUpdate()
 }
 
 // streamID must not be 0 here

flowcontrol/flow_control_manager_test.go

@@ -95,10 +95,10 @@ var _ = Describe("Flow Control Manager", func() {
 				Expect(err).ToNot(HaveOccurred())
 				err = fcm.AddBytesRead(4, 0x100-0x10)
 				Expect(err).ToNot(HaveOccurred())
-				doIt, offset, err := fcm.MaybeTriggerStreamWindowUpdate(4)
+				updates := fcm.GetWindowUpdates()
-				Expect(err).ToNot(HaveOccurred())
+				Expect(updates).To(HaveLen(1))
-				Expect(doIt).To(BeTrue())
+				Expect(updates[0].StreamID).To(Equal(protocol.StreamID(4)))
-				Expect(offset).ToNot(Equal(protocol.ByteCount(0x100)))
+				Expect(updates[0].Offset).To(Equal(protocol.ByteCount(0x1f0)))
 			})
 
 			It("gets connection level window updates", func() {
@@ -110,10 +110,15 @@ var _ = Describe("Flow Control Manager", func() {
 				Expect(err).ToNot(HaveOccurred())
 				err = fcm.AddBytesRead(6, 0x100-0x10)
 				Expect(err).ToNot(HaveOccurred())
-				doIt, offset := fcm.MaybeTriggerConnectionWindowUpdate()
+				updates := fcm.GetWindowUpdates()
-				Expect(err).ToNot(HaveOccurred())
+				Expect(updates).To(HaveLen(3))
-				Expect(doIt).To(BeTrue())
+				if updates[0].StreamID == 0 {
-				Expect(offset).ToNot(Equal(protocol.ByteCount(0x200)))
+					Expect(updates[0].Offset).ToNot(Equal(protocol.ByteCount(0x200)))
+				} else if updates[1].StreamID == 0 {
+					Expect(updates[1].Offset).ToNot(Equal(protocol.ByteCount(0x200)))
+				} else {
+					Expect(updates[2].Offset).ToNot(Equal(protocol.ByteCount(0x200)))
+				}
 			})
 		})
 	})

flowcontrol/interface.go

@@ -2,6 +2,12 @@ package flowcontrol
 
 import "github.com/lucas-clemente/quic-go/protocol"
 
+// WindowUpdate provides the data for WindowUpdateFrames.
+type WindowUpdate struct {
+	StreamID protocol.StreamID
+	Offset   protocol.ByteCount
+}
+
 // A FlowControlManager manages the flow control
 type FlowControlManager interface {
 	NewStream(streamID protocol.StreamID, contributesToConnectionFlow bool)
@@ -9,8 +15,7 @@ type FlowControlManager interface {
 	// methods needed for receiving data
 	UpdateHighestReceived(streamID protocol.StreamID, byteOffset protocol.ByteCount) error
 	AddBytesRead(streamID protocol.StreamID, n protocol.ByteCount) error
-	MaybeTriggerStreamWindowUpdate(streamID protocol.StreamID) (bool, protocol.ByteCount, error)
+	GetWindowUpdates() []WindowUpdate
-	MaybeTriggerConnectionWindowUpdate() (bool, protocol.ByteCount)
 	// methods needed for sending data
 	AddBytesSent(streamID protocol.StreamID, n protocol.ByteCount) error
 	SendWindowSize(streamID protocol.StreamID) (protocol.ByteCount, error)

session.go

@@ -659,25 +659,11 @@ func (s *Session) tryDecryptingQueuedPackets() {
 }
 
 func (s *Session) getWindowUpdateFrames() ([]*frames.WindowUpdateFrame, error) {
-	var res []*frames.WindowUpdateFrame
+	updates := s.flowControlManager.GetWindowUpdates()
-
+	res := make([]*frames.WindowUpdateFrame, len(updates))
-	s.streamsMap.Iterate(func(str *stream) (bool, error) {
+	for i, u := range updates {
-		id := str.StreamID()
+		res[i] = &frames.WindowUpdateFrame{StreamID: u.StreamID, ByteOffset: u.Offset}
-		doUpdate, offset, err := s.flowControlManager.MaybeTriggerStreamWindowUpdate(id)
-		if err != nil {
-			return false, err
 	}
-		if doUpdate {
-			res = append(res, &frames.WindowUpdateFrame{StreamID: id, ByteOffset: offset})
-		}
-		return true, nil
-	})
-
-	doUpdate, offset := s.flowControlManager.MaybeTriggerConnectionWindowUpdate()
-	if doUpdate {
-		res = append(res, &frames.WindowUpdateFrame{StreamID: 0, ByteOffset: offset})
-	}
-
 	return res, nil
 }
 

stream_test.go

@@ -44,12 +44,14 @@ func (m *mockFlowControlHandler) RemoveStream(streamID protocol.StreamID) {
 	delete(m.sendWindowSizes, streamID)
 }
 
-func (m *mockFlowControlHandler) MaybeTriggerStreamWindowUpdate(streamID protocol.StreamID) (bool, protocol.ByteCount, error) {
+func (m *mockFlowControlHandler) GetWindowUpdates() (res []flowcontrol.WindowUpdate) {
-	return m.triggerStreamWindowUpdate, 0x1337, nil
+	if m.triggerStreamWindowUpdate {
-}
+		res = append(res, flowcontrol.WindowUpdate{StreamID: 42, Offset: 0x1337})
-
+	}
-func (m *mockFlowControlHandler) MaybeTriggerConnectionWindowUpdate() (bool, protocol.ByteCount) {
+	if m.triggerConnectionWindowUpdate {
-	return m.triggerConnectionWindowUpdate, 0x1337
+		res = append(res, flowcontrol.WindowUpdate{StreamID: 0, Offset: 0x1337})
+	}
+	return res
 }
 
 func (m *mockFlowControlHandler) AddBytesRead(streamID protocol.StreamID, n protocol.ByteCount) error {