Stop using next_packet_sequence_number_length in QuicPacketCreator. No functional change. Protect…

net/quic/quic_connection.cc

 // 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.
 
 #include "net/quic/quic_connection.h"
 
 #include <string.h>
 #include <sys/types.h>
 
 #include <algorithm>
@@ skipping 1663 matching lines @@
     if (IsRetransmittable(*packet) == HAS_RETRANSMITTABLE_DATA &&
         last_send_for_timeout_ <= time_of_last_received_packet_) {
       last_send_for_timeout_ = packet_send_time;
     }
   }
   SetPingAlarm();
   MaybeSetMtuAlarm();
   DVLOG(1) << ENDPOINT << "time we began writing last sent packet: "
            << packet_send_time.ToDebuggingValue();
 
-  // TODO(ianswett): Change the packet number length and other packet creator
-  // options by a more explicit API than setting a struct value directly,
-  // perhaps via the NetworkChangeVisitor.
-  packet_generator_.UpdateSequenceNumberLength(
-      sent_packet_manager_->GetLeastPacketAwaitedByPeer(packet->path_id),
-      sent_packet_manager_->EstimateMaxPacketsInFlight(max_packet_length()));
+  if (!FLAGS_quic_simple_packet_number_length) {
+    // TODO(ianswett): Change the packet number length and other packet creator
+    // options by a more explicit API than setting a struct value directly,
+    // perhaps via the NetworkChangeVisitor.
+    packet_generator_.UpdateSequenceNumberLength(
+        sent_packet_manager_->GetLeastPacketAwaitedByPeer(packet->path_id),
+        sent_packet_manager_->EstimateMaxPacketsInFlight(max_packet_length()));
+  }
 
   bool reset_retransmission_alarm = sent_packet_manager_->OnPacketSent(
       packet, packet->original_path_id, packet->original_packet_number,
       packet_send_time, packet->transmission_type, IsRetransmittable(*packet));
 
   if (reset_retransmission_alarm || !retransmission_alarm_->IsSet()) {
     SetRetransmissionAlarm();
   }
 
+  if (FLAGS_quic_simple_packet_number_length) {
+    // The packet number length must be updated after OnPacketSent, because it
+    // may change the packet number length in packet.
+    packet_generator_.UpdateSequenceNumberLength(
+        sent_packet_manager_->GetLeastPacketAwaitedByPeer(packet->path_id),
+        sent_packet_manager_->EstimateMaxPacketsInFlight(max_packet_length()));
+  }
+
   stats_.bytes_sent += result.bytes_written;
   ++stats_.packets_sent;
   if (packet->transmission_type != NOT_RETRANSMISSION) {
     stats_.bytes_retransmitted += result.bytes_written;
     ++stats_.packets_retransmitted;
   }
 
   if (result.status == WRITE_STATUS_ERROR) {
     OnWriteError(result.error_code);
     DLOG(ERROR) << ENDPOINT << "failed writing " << encrypted_length
@@ skipping 792 matching lines @@
 // the sender and a signaling mechanism -- if the sender uses a
 // different MinRTO, we may get spurious retransmissions. May not have
 // any benefits, but if the delayed ack becomes a significant source
 // of (likely, tail) latency, then consider such a mechanism.
 const QuicTime::Delta QuicConnection::DelayedAckTime() {
   return QuicTime::Delta::FromMilliseconds(
       min(kMaxDelayedAckTimeMs, kMinRetransmissionTimeMs / 2));
 }
 
 }  // namespace net