Always send queued retransmission packets, because of write blocked socket, once the socket gets un…

net/quic/quic_unacked_packet_map.cc

 // Copyright 2014 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.
 
 #include "net/quic/quic_unacked_packet_map.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "net/quic/quic_bug_tracker.h"
 #include "net/quic/quic_connection_stats.h"
@@ skipping 72 matching lines @@
     unacked_packets_.pop_front();
     ++least_unacked_;
   }
 }
 
 void QuicUnackedPacketMap::TransferRetransmissionInfo(
     QuicPacketNumber old_packet_number,
     QuicPacketNumber new_packet_number,
     TransmissionType transmission_type,
     TransmissionInfo* info) {
-  if (old_packet_number < least_unacked_ ||
-      old_packet_number > largest_sent_packet_) {
-    QUIC_BUG << "Old TransmissionInfo no longer exists for:"
-             << old_packet_number << " least_unacked:" << least_unacked_
+  if (old_packet_number < least_unacked_) {
+    if (!FLAGS_quic_always_write_queued_retransmissions) {
+      QUIC_BUG << "Old TransmissionInfo no longer exists for:"
+               << old_packet_number << " least_unacked:" << least_unacked_;
+    }
+    // This can happen when a retransmission packet is queued because of write
+    // blocked socket, and the original packet gets acked before the
+    // retransmission gets sent.
+    return;
+  }
+  if (old_packet_number > largest_sent_packet_) {
+    QUIC_BUG << "Old TransmissionInfo never existed for :" << old_packet_number
              << " largest_sent:" << largest_sent_packet_;
     return;
   }
   DCHECK_GE(new_packet_number, least_unacked_ + unacked_packets_.size());
   DCHECK_NE(NOT_RETRANSMISSION, transmission_type);
 
   TransmissionInfo* transmission_info =
       &unacked_packets_.at(old_packet_number - least_unacked_);
   QuicFrames* frames = &transmission_info->retransmittable_frames;
   for (AckListenerWrapper& wrapper : transmission_info->ack_listeners) {
@@ skipping 236 matching lines @@
     }
   }
   return false;
 }
 
 QuicPacketNumber QuicUnackedPacketMap::GetLeastUnacked() const {
   return least_unacked_;
 }
 
 }  // namespace net