Cleanup in QUIC to merge the previous_transmissions_map in

net/quic/quic_sent_packet_manager.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_QUIC_QUIC_SENT_PACKET_MANAGER_H_
 #define NET_QUIC_QUIC_SENT_PACKET_MANAGER_H_
 
 #include <deque>
 #include <list>
 #include <map>
@@ skipping 186 matching lines @@
 
 
  private:
   friend class test::QuicConnectionPeer;
   friend class test::QuicSentPacketManagerPeer;
 
   struct TransmissionInfo {
     TransmissionInfo()
         : retransmittable_frames(NULL),
           sequence_number_length(PACKET_1BYTE_SEQUENCE_NUMBER),
-          sent_time(QuicTime::Zero()) { }
+          sent_time(QuicTime::Zero()),
+          previous_transmissions(NULL) { }
     TransmissionInfo(RetransmittableFrames* retransmittable_frames,
                      QuicSequenceNumberLength sequence_number_length)
         : retransmittable_frames(retransmittable_frames),
           sequence_number_length(sequence_number_length),
-          sent_time(QuicTime::Zero()) {
+          sent_time(QuicTime::Zero()),
+          previous_transmissions(NULL) {
     }
 
     RetransmittableFrames* retransmittable_frames;
     QuicSequenceNumberLength sequence_number_length;
     // Zero when the packet is serialized, non-zero once it's sent.
     QuicTime sent_time;
+    // Stores all previous transmissions if the packet has been retransmitted,
+    // and is NULL otherwise.
+    SequenceNumberSet* previous_transmissions;
   };
 
   typedef linked_hash_map<QuicPacketSequenceNumber,
                           TransmissionInfo> UnackedPacketMap;
   typedef linked_hash_map<QuicPacketSequenceNumber,
                           TransmissionType> PendingRetransmissionMap;
   typedef base::hash_map<QuicPacketSequenceNumber, SequenceNumberSet*>
                          PreviousTransmissionMap;
 
   // Process the incoming ack looking for newly ack'd data packets.
@@ skipping 16 matching lines @@
   // retransmissions.  Returns false if there are no retransmittable frames for
   // |sequence_number| and true if it will be retransmitted.
   bool MarkForRetransmission(QuicPacketSequenceNumber sequence_number,
                              TransmissionType transmission_type);
 
   // Returns the length of the serialized sequence number for
   // the packet |sequence_number|.
   QuicSequenceNumberLength GetSequenceNumberLength(
       QuicPacketSequenceNumber sequence_number) const;
 
-  // Returns the sequence number of the packet that |sequence_number| was
-  // most recently transmitted as.
-  QuicPacketSequenceNumber GetMostRecentTransmission(
-      QuicPacketSequenceNumber sequence_number) const;
-
   // Clears up to |num_to_clear| previous transmissions in order to make room
   // in the ack frame for new acks.
   void ClearPreviousRetransmissions(size_t num_to_clear);
 
   void CleanupPacketHistory();
 
   // Newly serialized retransmittable and fec packets are added to this map,
   // which contains owning pointers to any contained frames.  If a packet is
   // retransmitted, this map will contain entries for both the old and the new
   // packet. The old packet's retransmittable frames entry will be NULL, while
   // the new packet's entry will contain the frames to retransmit.
   // If the old packet is acked before the new packet, then the old entry will
   // be removed from the map and the new entry's retransmittable frames will be
   // set to NULL.
   UnackedPacketMap unacked_packets_;
 
   // Pending retransmissions which have not been packetized and sent yet.
   PendingRetransmissionMap pending_retransmissions_;
 
-  // Map from sequence number to set of all sequence number that this packet has
-  // been transmitted as.  If a packet has not been retransmitted, it will not
-  // have an entry in this map.  If any transmission of a packet has been acked
-  // it will not have an entry in this map.
-  PreviousTransmissionMap previous_transmissions_map_;
-
   // Tracks if the connection was created by the server.
   bool is_server_;
 
   HelperInterface* helper_;
 
   // An AckNotifier can register to be informed when ACKs have been received for
   // all packets that a given block of data was sent in. The AckNotifierManager
   // maintains the currently active notifiers.
   AckNotifierManager ack_notifier_manager_;
 
   const QuicClock* clock_;
   scoped_ptr<SendAlgorithmInterface> send_algorithm_;
   // Tracks the send time, size, and nack count of sent packets.  Packets are
   // removed after 5 seconds and they've been removed from pending_packets_.
   SendAlgorithmInterface::SentPacketsMap packet_history_map_;
   // Packets that are outstanding and have not been abandoned or lost.
   SequenceNumberSet pending_packets_;
   QuicTime::Delta rtt_sample_;  // RTT estimate from the most recent ACK.
   // Number of times the RTO timer has fired in a row without receiving an ack.
   size_t consecutive_rto_count_;
   bool using_pacing_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicSentPacketManager);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_SENT_PACKET_MANAGER_H_