delete receivedTimes when receiving a StopWaiting in new AckHandler

ref #239

ackhandler/received_packet_handler.go

@@ -28,7 +28,8 @@ type receivedPacketHandler struct {
 	currentAckFrame        *frames.AckFrame
 	stateChanged           bool // has an ACK for this state already been sent? Will be set to false every time a new packet arrives, and to false every time an ACK is sent
 
-	packetHistory         *receivedPacketHistory
+	packetHistory *receivedPacketHistory
+
 	receivedTimes         map[protocol.PacketNumber]time.Time
 	lowestInReceivedTimes protocol.PacketNumber
 }
@@ -72,8 +73,6 @@ func (h *receivedPacketHandler) ReceivedPacket(packetNumber protocol.PacketNumbe
 
 	h.receivedTimes[packetNumber] = time.Now()
 
-	h.garbageCollect()
-
 	if uint32(len(h.receivedTimes)) > protocol.MaxTrackedReceivedPackets {
 		return errTooManyOutstandingReceivedPackets
 	}
@@ -88,6 +87,7 @@ func (h *receivedPacketHandler) ReceivedStopWaiting(f *frames.StopWaitingFrame)
 	}
 
 	h.ignorePacketsBelow = f.LeastUnacked - 1
+	h.garbageCollectReceivedTimes()
 
 	// ignore if StopWaiting is unneeded, since all packets below have already been received
 	if h.largestInOrderObserved >= f.LeastUnacked {
@@ -99,8 +99,6 @@ func (h *receivedPacketHandler) ReceivedStopWaiting(f *frames.StopWaitingFrame)
 
 	h.packetHistory.DeleteBelow(f.LeastUnacked)
 
-	h.garbageCollect()
-
 	return nil
 }
 
@@ -136,9 +134,9 @@ func (h *receivedPacketHandler) GetAckFrame(dequeue bool) (*frames.AckFrame, err
 	return h.currentAckFrame, nil
 }
 
-func (h *receivedPacketHandler) garbageCollect() {
-	for i := h.lowestInReceivedTimes; i < h.largestInOrderObserved; i++ {
+func (h *receivedPacketHandler) garbageCollectReceivedTimes() {
+	for i := h.lowestInReceivedTimes; i <= h.ignorePacketsBelow; i++ {
 		delete(h.receivedTimes, i)
 	}
-	h.lowestInReceivedTimes = h.largestInOrderObserved
+	h.lowestInReceivedTimes = h.ignorePacketsBelow
 }

ackhandler/received_packet_handler_test.go

@@ -249,21 +249,42 @@ var _ = Describe("receivedPacketHandler", func() {
 	})
 
 	Context("Garbage Collector", func() {
-		PIt("only keeps packets with packet numbers higher than the highestInOrderObserved in packetHistory", func() {
-			handler.ReceivedPacket(1, false)
-			handler.ReceivedPacket(2, false)
-			handler.ReceivedPacket(4, false)
+		It("garbage collects receivedTimes after receiving a StopWaiting, if there are no missing packets", func() {
+			for i := 1; i <= 4; i++ {
+				err := handler.ReceivedPacket(protocol.PacketNumber(i), false)
+				Expect(err).ToNot(HaveOccurred())
+			}
+			err := handler.ReceivedStopWaiting(&frames.StopWaitingFrame{LeastUnacked: 3})
+			Expect(err).ToNot(HaveOccurred())
 			Expect(handler.receivedTimes).ToNot(HaveKey(protocol.PacketNumber(1)))
-			Expect(handler.receivedTimes).To(HaveKey(protocol.PacketNumber(2)))
+			Expect(handler.receivedTimes).ToNot(HaveKey(protocol.PacketNumber(2)))
+			Expect(handler.receivedTimes).To(HaveKey(protocol.PacketNumber(3)))
 			Expect(handler.receivedTimes).To(HaveKey(protocol.PacketNumber(4)))
 		})
 
-		It("garbage collects packetHistory after receiving a StopWaiting", func() {
-			handler.ReceivedPacket(1, false)
-			handler.ReceivedPacket(2, false)
-			handler.ReceivedPacket(4, false)
-			swf := frames.StopWaitingFrame{LeastUnacked: 4}
-			handler.ReceivedStopWaiting(&swf)
+		It("garbage collects the receivedTimes after receiving multiple StopWaitings", func() {
+			for i := 1; i <= 9; i++ {
+				err := handler.ReceivedPacket(protocol.PacketNumber(i), false)
+				Expect(err).ToNot(HaveOccurred())
+			}
+			err := handler.ReceivedStopWaiting(&frames.StopWaitingFrame{LeastUnacked: 4})
+			Expect(err).ToNot(HaveOccurred())
+			err = handler.ReceivedStopWaiting(&frames.StopWaitingFrame{LeastUnacked: 8})
+			Expect(err).ToNot(HaveOccurred())
+			Expect(handler.receivedTimes).To(HaveLen(2)) // packets 8 and 9
+			Expect(handler.receivedTimes).To(HaveKey(protocol.PacketNumber(8)))
+			Expect(handler.receivedTimes).To(HaveKey(protocol.PacketNumber(9)))
+		})
+
+		It("garbage collects receivedTimes after receiving a StopWaiting, if there are missing packets", func() {
+			err := handler.ReceivedPacket(1, false)
+			Expect(err).ToNot(HaveOccurred())
+			err = handler.ReceivedPacket(2, false)
+			Expect(err).ToNot(HaveOccurred())
+			err = handler.ReceivedPacket(4, false)
+			Expect(err).ToNot(HaveOccurred())
+			err = handler.ReceivedStopWaiting(&frames.StopWaitingFrame{LeastUnacked: 4})
+			Expect(err).ToNot(HaveOccurred())
 			Expect(handler.receivedTimes).ToNot(HaveKey(protocol.PacketNumber(1)))
 			Expect(handler.receivedTimes).ToNot(HaveKey(protocol.PacketNumber(2)))
 			Expect(handler.receivedTimes).To(HaveKey(protocol.PacketNumber(4)))