Land Recent QUIC Changes.

net/quic/quic_unacked_packet_map.h

Index: net/quic/quic_unacked_packet_map.h
diff --git a/net/quic/quic_unacked_packet_map.h b/net/quic/quic_unacked_packet_map.h
index 610639c68d865488cedf94ceff8c24f73b0261cf..02634226e9d6926592abbc46a3497bc18f22b6b9 100644
--- a/net/quic/quic_unacked_packet_map.h
+++ b/net/quic/quic_unacked_packet_map.h
@@ -10,15 +10,16 @@
 
 namespace net {
 
-// Class which tracks unacked packets, including those packets which are
-// currently pending, and the relationship between packets which
-// contain the same data (via retransmissions)
+// Class which tracks unacked packets for three purposes:
+// 1) Track retransmittable data, including multiple transmissions of frames.
+// 2) Track packets and bytes in flight for congestion control.
+// 3) Track sent time of packets to provide RTT measurements from acks.
 class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
  public:
   QuicUnackedPacketMap();
   ~QuicUnackedPacketMap();
 
-  // Adds |serialized_packet| to the map.  Does not mark it pending.
+  // Adds |serialized_packet| to the map.  Does not mark it in flight.
   void AddPacket(const SerializedPacket& serialized_packet);
 
   // Called when a packet is retransmitted with a new sequence number.
@@ -35,8 +36,8 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
   void NackPacket(QuicPacketSequenceNumber sequence_number,
                   size_t min_nacks);
 
-  // Marks |sequence_number| as no longer pending.
-  void SetNotPending(QuicPacketSequenceNumber sequence_number);
+  // Marks |sequence_number| as no longer in flight.
+  void RemoveFromInFlight(QuicPacketSequenceNumber sequence_number);
 
   // Returns true if the unacked packet |sequence_number| has retransmittable
   // frames.  This will return false if the packet has been acked, if a
@@ -57,7 +58,7 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
     return largest_sent_packet_;
   }
 
-  // Returns the sum of the bytes in all pending packets.
+  // Returns the sum of bytes from all packets in flight.
   QuicByteCount bytes_in_flight() const {
     return bytes_in_flight_;
   }
@@ -67,13 +68,13 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
   QuicPacketSequenceNumber GetLeastUnackedSentPacket() const;
 
   // Sets a packet as sent with the sent time |sent_time|.  Marks the packet
-  // as pending and tracks the |bytes_sent| if |set_pending| is true.
-  // Packets marked as pending are expected to be marked as missing when they
+  // as in flight if |set_in_flight| is true.
+  // Packets marked as in flight are expected to be marked as missing when they
   // don't arrive, indicating the need for retransmission.
   void SetSent(QuicPacketSequenceNumber sequence_number,
                QuicTime sent_time,
                QuicByteCount bytes_sent,
-               bool set_pending);
+               bool set_in_flight);
 
   // Clears up to |num_to_clear| previous transmissions in order to make room
   // in the ack frame for new acks.
@@ -87,8 +88,8 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
   const_iterator begin() const { return unacked_packets_.begin(); }
   const_iterator end() const { return unacked_packets_.end(); }
 
-  // Returns true if there are unacked packets that are pending.
-  bool HasPendingPackets() const;
+  // Returns true if there are unacked packets that are in flight.
+  bool HasInFlightPackets() const;
 
   // Returns the TransmissionInfo associated with |sequence_number|, which
   // must be unacked.
@@ -98,42 +99,35 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
   // Returns the time that the last unacked packet was sent.
   QuicTime GetLastPacketSentTime() const;
 
-  // Returns the time that the first pending packet was sent.
-  QuicTime GetFirstPendingPacketSentTime() const;
+  // Returns the time that the first in flight packet was sent.
+  QuicTime GetFirstInFlightPacketSentTime() const;
 
   // Returns the number of unacked packets.
   size_t GetNumUnackedPackets() const;
 
-  // Returns true if there are multiple packet pending.
-  bool HasMultiplePendingPackets() const;
+  // Returns true if there are multiple packets in flight.
+  bool HasMultipleInFlightPackets() const;
 
   // Returns true if there are any pending crypto packets.
   bool HasPendingCryptoPackets() const;
 
   // Removes any retransmittable frames from this transmission or an associated
-  // transmission.  It removes any nnon-pending transmissions less than or
-  // equal to |largest_observed|, and disconnects any other packets from other
-  // transmissions.
-  // TODO(ianswett): Remove largest_observed_ once the map tracks whether a
-  // transmission is useful for RTT purposes internally.
-  void RemoveRetransmittability(QuicPacketSequenceNumber sequence_number,
-                                QuicPacketSequenceNumber largest_observed_);
-
-  // Removes an entry from the unacked packet map which is not pending, has
-  // no retransmittable frames, and no associated transmissions.
-  // TODO(ianswett): Remove or make this method private once the map tracks
-  // the three reasons for tracking a packet correctly.
-  void RemoveRttOnlyPacket(QuicPacketSequenceNumber sequence_number);
-
-  // Returns true if the packet's only purpose is to measure RTT.  It must not
-  // be pending, have retransmittable frames, or be linked to transmissions
-  // with retransmittable frames.
-  static bool IsForRttOnly(const TransmissionInfo& transmission_info);
+  // transmission.  It removes now useless transmissions, and disconnects any
+  // other packets from other transmissions.
+  void RemoveRetransmittability(QuicPacketSequenceNumber sequence_number);
+
+  // Increases the largest observed.  Any packets less or equal to
+  // |largest_acked_packet| are discarded if they are only for the RTT purposes.
+  void IncreaseLargestObserved(QuicPacketSequenceNumber largest_observed);
 
  private:
   void MaybeRemoveRetransmittableFrames(TransmissionInfo* transmission_info);
 
+  // Returns true if the packet no longer has a purpose in the map.
+  bool IsPacketUseless(UnackedPacketMap::const_iterator it) const;
+
   QuicPacketSequenceNumber largest_sent_packet_;
+  QuicPacketSequenceNumber largest_observed_;
 
   // Newly serialized retransmittable and fec packets are added to this map,
   // which contains owning pointers to any contained frames.  If a packet is
@@ -146,7 +140,7 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
   UnackedPacketMap unacked_packets_;
 
   size_t bytes_in_flight_;
-  // Number of outstanding crypto handshake packets.
+  // Number of retransmittable crypto handshake packets.
   size_t pending_crypto_packet_count_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicUnackedPacketMap);