From 3e5f43f45ae27a47c73b9cd06be789ba1eb20889 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Fri, 22 Apr 2016 17:50:04 +0700
Subject: [PATCH] calculate the Entropy byte for the highest in order received
 packet

---
 ackhandler/incoming_packet_ack_handler.go     |  8 +++--
 .../incoming_packet_ack_handler_test.go       | 34 ++++++++++++++++++-
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/ackhandler/incoming_packet_ack_handler.go b/ackhandler/incoming_packet_ack_handler.go
index 5203ed906..702d7d127 100644
--- a/ackhandler/incoming_packet_ack_handler.go
+++ b/ackhandler/incoming_packet_ack_handler.go
@@ -11,9 +11,10 @@ var ErrDuplicatePacket = errors.New("Duplicate Packet")
 
 // The AckHandler handles ACKs
 type incomingPacketAckHandler struct {
-	highestInOrderObserved protocol.PacketNumber
-	largestObserved        protocol.PacketNumber
-	packetHistory          map[protocol.PacketNumber]bool
+	highestInOrderObserved        protocol.PacketNumber
+	highestInOrderObservedEntropy EntropyAccumulator
+	largestObserved               protocol.PacketNumber
+	packetHistory                 map[protocol.PacketNumber]bool
 }
 
 // NewIncomingPacketAckHandler creates a new outgoingPacketAckHandler
@@ -37,6 +38,7 @@ func (h *incomingPacketAckHandler) ReceivedPacket(packetNumber protocol.PacketNu
 
 	if packetNumber == h.highestInOrderObserved+1 {
 		h.highestInOrderObserved = packetNumber
+		h.highestInOrderObservedEntropy.Add(packetNumber, entropyBit)
 	}
 
 	h.packetHistory[packetNumber] = true
diff --git a/ackhandler/incoming_packet_ack_handler_test.go b/ackhandler/incoming_packet_ack_handler_test.go
index 62393f7ed..a1b7057eb 100644
--- a/ackhandler/incoming_packet_ack_handler_test.go
+++ b/ackhandler/incoming_packet_ack_handler_test.go
@@ -48,7 +48,39 @@ var _ = Describe("incomingPacketAckHandler", func() {
 	})
 
 	Context("Entropy calculation", func() {
-		// It("calculates the entropy f")
+		It("calculates the entropy for continously received packets", func() {
+			entropy := EntropyAccumulator(0)
+			for i := 1; i < 100; i++ {
+				entropyBit := false
+				if i%3 == 0 || i%5 == 0 {
+					entropyBit = true
+				}
+				entropy.Add(protocol.PacketNumber(i), entropyBit)
+				err := handler.ReceivedPacket(protocol.PacketNumber(i), entropyBit)
+				Expect(err).ToNot(HaveOccurred())
+			}
+			Expect(handler.highestInOrderObservedEntropy).To(Equal(entropy))
+		})
+
+		It("calculates the entropy if there is a NACK range", func() {
+			entropy := EntropyAccumulator(0)
+			for i := 1; i < 100; i++ {
+				entropyBit := false
+				if i%3 == 0 || i%5 == 0 {
+					entropyBit = true
+				}
+
+				if i == 10 || i == 11 || i == 12 {
+					continue
+				}
+				if i < 10 {
+					entropy.Add(protocol.PacketNumber(i), entropyBit)
+				}
+				err := handler.ReceivedPacket(protocol.PacketNumber(i), entropyBit)
+				Expect(err).ToNot(HaveOccurred())
+			}
+			Expect(handler.highestInOrderObservedEntropy).To(Equal(entropy))
+		})
 	})
 
 	Context("NACK range calculation", func() {