Cancel pending retransmissions which are greater than the largest newly acked packet when using the…

net/quic/quic_protocol.h

 // Copyright (c) 2012 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_PROTOCOL_H_
 #define NET_QUIC_QUIC_PROTOCOL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 1424 matching lines @@
   QuicFrames retransmittable_frames;
   EncryptionLevel encryption_level;
   QuicPacketNumberLength packet_number_length;
   QuicPacketLength bytes_sent;
   uint16_t nack_count;
   QuicTime sent_time;
   // Reason why this packet was transmitted.
   TransmissionType transmission_type;
   // In flight packets have not been abandoned or lost.
   bool in_flight;
-  // True if the packet can never be acked, so it can be removed.
+  // True if the packet can never be acked, so it can be removed.  Occurs when
+  // a packet is never sent, after it is acknowledged once, or if it's a crypto
+  // packet we never expect to receive an ack for.
   bool is_unackable;
   // True if the packet contains stream data from the crypto stream.
   bool has_crypto_handshake;
   // Non-zero if the packet needs padding if it's retransmitted.
   int num_padding_bytes;
   // Stores the packet number of the next retransmission of this packet.
   // Zero if the packet has not been retransmitted.
   QuicPacketNumber retransmission;
   // Non-empty if there is a listener for this packet.
   std::list<AckListenerWrapper> ack_listeners;
@@ skipping 35 matching lines @@
       : iov(iov), iov_count(iov_count), total_length(total_length) {}
 
   const struct iovec* iov;
   const int iov_count;
   const size_t total_length;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PROTOCOL_H_