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

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 1719 matching lines @@
   QuicPacketNumber packet_number = packet.packet_number;
   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE &&
       packet.encryption_level == ENCRYPTION_NONE) {
     // Drop packets that are NULL encrypted since the peer won't accept them
     // anymore.
     DVLOG(1) << ENDPOINT << "Dropping NULL encrypted packet: " << packet_number
              << " since the connection is forward secure.";
     return true;
   }
 
+  // TODO(fayang): Remove IsUnacked and HasRetransmittableFrames from
+  // QuicSentPacketManagerInterface when deprecating
+  // gfe2_reloadable_flag_quic_always_write_queued_retransmissions.
+  if (FLAGS_quic_always_write_queued_retransmissions) {
+    return false;
+  }
+
   // If a retransmission has been acked before sending, don't send it.
   // This occurs if a packet gets serialized, queued, then discarded.
   if (packet.transmission_type != NOT_RETRANSMISSION &&
       (!sent_packet_manager_->IsUnacked(packet.original_path_id,
                                         packet.original_packet_number) ||
        !sent_packet_manager_->HasRetransmittableFrames(
            packet.original_path_id, packet.original_packet_number))) {
     DVLOG(1) << ENDPOINT << "Dropping unacked packet: " << packet_number
              << " A previous transmission was acked while write blocked.";
     return true;
@@ skipping 756 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