Landing Recent QUIC Changes.

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>
 #include <iterator>
@@ skipping 38 matching lines @@
 const QuicPacketSequenceNumber kMaxPacketGap = 5000;
 
 // Limit the number of FEC groups to two.  If we get enough out of order packets
 // that this becomes limiting, we can revisit.
 const size_t kMaxFecGroups = 2;
 
 // Limit the number of undecryptable packets we buffer in
 // expectation of the CHLO/SHLO arriving.
 const size_t kMaxUndecryptablePackets = 10;
 
+// Maximum number of acks received before sending an ack in response.
+const size_t kMaxPacketsReceivedBeforeAckSend = 20;
+
 bool Near(QuicPacketSequenceNumber a, QuicPacketSequenceNumber b) {
   QuicPacketSequenceNumber delta = (a > b) ? a - b : b - a;
   return delta <= kMaxPacketGap;
 }
 
 // An alarm that is scheduled to send an ack if a timeout occurs.
 class AckAlarm : public QuicAlarm::Delegate {
  public:
   explicit AckAlarm(QuicConnection* connection)
       : connection_(connection) {
@@ skipping 116 matching lines @@
       peer_address_(address),
       migrating_peer_port_(0),
       last_packet_revived_(false),
       last_size_(0),
       last_decrypted_packet_level_(ENCRYPTION_NONE),
       largest_seen_packet_with_ack_(0),
       largest_seen_packet_with_stop_waiting_(0),
       pending_version_negotiation_packet_(false),
       received_packet_manager_(&stats_),
       ack_queued_(false),
+      num_packets_received_since_last_ack_sent_(0),
       stop_waiting_count_(0),
       ack_alarm_(helper->CreateAlarm(new AckAlarm(this))),
       retransmission_alarm_(helper->CreateAlarm(new RetransmissionAlarm(this))),
       send_alarm_(helper->CreateAlarm(new SendAlarm(this))),
       resume_writes_alarm_(helper->CreateAlarm(new SendAlarm(this))),
       timeout_alarm_(helper->CreateAlarm(new TimeoutAlarm(this))),
       ping_alarm_(helper->CreateAlarm(new PingAlarm(this))),
       packet_generator_(connection_id_, &framer_, random_generator_, this),
       idle_network_timeout_(
           QuicTime::Delta::FromSeconds(kDefaultInitialTimeoutSecs)),
@@ skipping 569 matching lines @@
            << last_congestion_frames_.size() << " congestions, "
            << last_stop_waiting_frames_.size() << " stop_waiting, "
            << last_rst_frames_.size() << " rsts, "
            << last_goaway_frames_.size() << " goaways, "
            << last_window_update_frames_.size() << " window updates, "
            << last_blocked_frames_.size() << " blocked, "
            << last_ping_frames_.size() << " pings, "
            << last_close_frames_.size() << " closes, "
            << "for " << last_header_.public_header.connection_id;
 
+  ++num_packets_received_since_last_ack_sent_;
+
   // Call MaybeQueueAck() before recording the received packet, since we want
   // to trigger an ack if the newly received packet was previously missing.
   MaybeQueueAck();
 
   // Record received or revived packet to populate ack info correctly before
   // processing stream frames, since the processing may result in a response
   // packet with a bundled ack.
   if (last_packet_revived_) {
     received_packet_manager_.RecordPacketRevived(
         last_header_.packet_sequence_number);
@@ skipping 113 matching lines @@
       !last_rst_frames_.empty() ||
       !last_window_update_frames_.empty() ||
       !last_blocked_frames_.empty() ||
       !last_ping_frames_.empty()) {
     return true;
   }
 
   if (!last_ack_frames_.empty() && last_ack_frames_.back().is_truncated) {
     return true;
   }
+  // Always send an ack every 20 packets in order to allow the peer to discard
+  // information from the SentPacketManager and provide an RTT measurement.
+  if (num_packets_received_since_last_ack_sent_ >=
+          kMaxPacketsReceivedBeforeAckSend) {
+    return true;
+  }
   return false;
 }
 
 void QuicConnection::UpdateStopWaitingCount() {
   if (last_ack_frames_.empty()) {
     return;
   }
 
   // If the peer is still waiting for a packet that we are no longer planning to
   // send, send an ack to raise the high water mark.
@@ skipping 344 matching lines @@
   // We should serialize handshake packets immediately to ensure that they
   // end up sent at the right encryption level.
   if (handshake == IS_HANDSHAKE) {
     return true;
   }
 
   return CanWrite(retransmittable);
 }
 
 bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) {
+  if (!connected_) {
+    return false;
+  }
+
   if (writer_->IsWriteBlocked()) {
     visitor_->OnWriteBlocked();
     return false;
   }
 
   QuicTime now = clock_->Now();
   QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(
       now, retransmittable);
   if (delay.IsInfinite()) {
     send_alarm_->Cancel();
@@ skipping 256 matching lines @@
       DLOG(ERROR) << "Unable to send ping!?";
     }
   } else {
     packet_generator_.AddControlFrame(QuicFrame(new QuicPingFrame));
   }
 }
 
 void QuicConnection::SendAck() {
   ack_alarm_->Cancel();
   stop_waiting_count_ = 0;
+  num_packets_received_since_last_ack_sent_ = 0;
   bool send_feedback = false;
 
   // Deprecating the Congestion Feedback Frame after QUIC_VERSION_22.
   if (version() <= QUIC_VERSION_22) {
     if (received_packet_manager_.GenerateCongestionFeedback(
             &outgoing_congestion_feedback_)) {
       DVLOG(1) << ENDPOINT << "Sending feedback: "
                << outgoing_congestion_feedback_;
       send_feedback = true;
     }
@@ skipping 426 matching lines @@
   }
   for (size_t i = 0; i < retransmittable_frames->frames().size(); ++i) {
     if (retransmittable_frames->frames()[i].type == CONNECTION_CLOSE_FRAME) {
       return true;
     }
   }
   return false;
 }
 
 }  // namespace net