Revert of Landing Recent QUIC Changes.

net/quic/quic_sent_packet_manager.cc

Index: net/quic/quic_sent_packet_manager.cc
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index c592e133a2c99892ae72119de8fe85efd0185618..21a4fbcd84b6f16856a8ba4e21e8f2a851baee31 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -144,11 +144,8 @@
   if (serialized_packet.retransmittable_frames) {
     ack_notifier_manager_.OnSerializedPacket(serialized_packet);
   }
+
   unacked_packets_.AddPacket(serialized_packet);
-
-  if (debug_delegate_ != NULL) {
-    debug_delegate_->OnSerializedPacket(serialized_packet);
-  }
 }
 
 void QuicSentPacketManager::OnRetransmittedPacket(
@@ -197,7 +194,6 @@
   HandleAckForSentPackets(ack_frame);
   InvokeLossDetection(ack_receive_time);
   MaybeInvokeCongestionEvent(largest_observed_acked, bytes_in_flight);
-  unacked_packets_.RemoveObsoletePackets();
 
   sustained_bandwidth_recorder_.RecordEstimate(
       send_algorithm_->InRecovery(),
@@ -261,15 +257,15 @@
   // incoming_ack shows they've been seen by the peer.
   QuicTime::Delta delta_largest_observed =
       ack_frame.delta_time_largest_observed;
-  QuicPacketSequenceNumber sequence_number = unacked_packets_.GetLeastUnacked();
-  for (QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
-       it != unacked_packets_.end(); ++it, ++sequence_number) {
+  QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
+  while (it != unacked_packets_.end()) {
+    QuicPacketSequenceNumber sequence_number = it->first;
     if (sequence_number > ack_frame.largest_observed) {
       // These packets are still in flight.
       break;
     }
 
-    if (ContainsKey(ack_frame.missing_packets, sequence_number)) {
+    if (IsAwaitingPacket(ack_frame, sequence_number)) {
       // Consider it multiple nacks when there is a gap between the missing
       // packet and the largest observed, since the purpose of a nack
       // threshold is to tolerate re-ordering.  This handles both StretchAcks
@@ -281,16 +277,17 @@
         min_nacks = 1;
       }
       unacked_packets_.NackPacket(sequence_number, min_nacks);
+      ++it;
       continue;
     }
     // Packet was acked, so remove it from our unacked packet list.
     DVLOG(1) << ENDPOINT << "Got an ack for packet " << sequence_number;
     // If data is associated with the most recent transmission of this
     // packet, then inform the caller.
-    if (it->in_flight) {
-      packets_acked_[sequence_number] = *it;
-    }
-    MarkPacketHandled(sequence_number, *it, delta_largest_observed);
+    if (it->second.in_flight) {
+      packets_acked_[sequence_number] = it->second;
+    }
+    it = MarkPacketHandled(it, delta_largest_observed);
   }
 
   // Discard any retransmittable frames associated with revived packets.
@@ -308,25 +305,26 @@
 
 void QuicSentPacketManager::RetransmitUnackedPackets(
     RetransmissionType retransmission_type) {
-  QuicPacketSequenceNumber sequence_number = unacked_packets_.GetLeastUnacked();
-  for (QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
-       it != unacked_packets_.end(); ++it, ++sequence_number) {
-    const RetransmittableFrames* frames = it->retransmittable_frames;
+  QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
+  while (it != unacked_packets_.end()) {
+    const RetransmittableFrames* frames = it->second.retransmittable_frames;
     // TODO(ianswett): Consider adding a new retransmission type which removes
     // all these old packets from unacked and retransmits them as new sequence
     // numbers with no connection to the previous ones.
     if (frames != NULL && (retransmission_type == ALL_PACKETS ||
                            frames->encryption_level() == ENCRYPTION_INITIAL)) {
-      MarkForRetransmission(sequence_number, ALL_UNACKED_RETRANSMISSION);
-    }
+      MarkForRetransmission(it->first, ALL_UNACKED_RETRANSMISSION);
+    }
+    ++it;
   }
 }
 
 void QuicSentPacketManager::NeuterUnencryptedPackets() {
-  QuicPacketSequenceNumber sequence_number = unacked_packets_.GetLeastUnacked();
-  for (QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
-       it != unacked_packets_.end(); ++it, ++sequence_number) {
-    const RetransmittableFrames* frames = it->retransmittable_frames;
+  QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
+  while (it != unacked_packets_.end()) {
+    const RetransmittableFrames* frames = it->second.retransmittable_frames;
+    QuicPacketSequenceNumber sequence_number = it->first;
+    ++it;
     if (frames != NULL && frames->encryption_level() == ENCRYPTION_NONE) {
       // Once you're forward secure, no unencrypted packets will be sent, crypto
       // or otherwise. Unencrypted packets are neutered and abandoned, to ensure
@@ -334,6 +332,8 @@
       // perspective.
       pending_retransmissions_.erase(sequence_number);
       unacked_packets_.RemoveFromInFlight(sequence_number);
+      // RemoveRetransmittibility is safe because only the newest sequence
+      // number can have frames.
       unacked_packets_.RemoveRetransmittability(sequence_number);
     }
   }
@@ -358,7 +358,7 @@
 }
 
 void QuicSentPacketManager::RecordSpuriousRetransmissions(
-    const SequenceNumberList& all_transmissions,
+    const SequenceNumberSet& all_transmissions,
     QuicPacketSequenceNumber acked_sequence_number) {
   if (acked_sequence_number < first_rto_transmission_) {
     // Cancel all pending RTO transmissions and restore their in flight status.
@@ -376,9 +376,11 @@
     first_rto_transmission_ = 0;
     ++stats_->spurious_rto_count;
   }
-  for (SequenceNumberList::const_reverse_iterator it =
-           all_transmissions.rbegin();
-       it != all_transmissions.rend() && *it > acked_sequence_number; ++it) {
+  for (SequenceNumberSet::const_iterator
+           it = all_transmissions.upper_bound(acked_sequence_number),
+           end = all_transmissions.end();
+       it != end;
+       ++it) {
     const TransmissionInfo& retransmit_info =
         unacked_packets_.GetTransmissionInfo(*it);
 
@@ -436,8 +438,7 @@
   const TransmissionInfo& transmission_info =
       unacked_packets_.GetTransmissionInfo(sequence_number);
   QuicPacketSequenceNumber newest_transmission =
-      transmission_info.all_transmissions == NULL ?
-          sequence_number : *transmission_info.all_transmissions->rbegin();
+      *transmission_info.all_transmissions->rbegin();
   // This packet has been revived at the receiver. If we were going to
   // retransmit it, do not retransmit it anymore.
   pending_retransmissions_.erase(newest_transmission);
@@ -452,36 +453,53 @@
   unacked_packets_.RemoveRetransmittability(sequence_number);
 }
 
-void QuicSentPacketManager::MarkPacketHandled(
-    QuicPacketSequenceNumber sequence_number,
-    const TransmissionInfo& info,
+QuicUnackedPacketMap::const_iterator QuicSentPacketManager::MarkPacketHandled(
+    QuicUnackedPacketMap::const_iterator it,
     QuicTime::Delta delta_largest_observed) {
+  LOG_IF(DFATAL, it == unacked_packets_.end())
+      << "MarkPacketHandled must be passed a valid iterator entry.";
+  const QuicPacketSequenceNumber sequence_number = it->first;
+  const TransmissionInfo& transmission_info = it->second;
+
   QuicPacketSequenceNumber newest_transmission =
-      info.all_transmissions == NULL ?
-          sequence_number : *info.all_transmissions->rbegin();
+      *transmission_info.all_transmissions->rbegin();
   // Remove the most recent packet, if it is pending retransmission.
   pending_retransmissions_.erase(newest_transmission);
 
-  // The AckNotifierManager needs to be notified about the most recent
-  // transmission, since that's the one only one it tracks.
-  ack_notifier_manager_.OnPacketAcked(newest_transmission,
-                                      delta_largest_observed);
-  if (newest_transmission != sequence_number) {
-    RecordSpuriousRetransmissions(*info.all_transmissions, sequence_number);
-    // Remove the most recent packet from flight if it's a crypto handshake
-    // packet, since they won't be acked now that one has been processed.
-    // Other crypto handshake packets won't be in flight, only the newest
-    // transmission of a crypto packet is in flight at once.
-    // TODO(ianswett): Instead of handling all crypto packets special,
-    // only handle NULL encrypted packets in a special way.
-    if (HasCryptoHandshake(
-        unacked_packets_.GetTransmissionInfo(newest_transmission))) {
-      unacked_packets_.RemoveFromInFlight(newest_transmission);
-    }
-  }
-
+  // Notify observers about the ACKed packet.
+  {
+    // The AckNotifierManager needs to be notified about the most recent
+    // transmission, since that's the one only one it tracks.
+    ack_notifier_manager_.OnPacketAcked(newest_transmission,
+                                        delta_largest_observed);
+    if (newest_transmission != sequence_number) {
+      RecordSpuriousRetransmissions(*transmission_info.all_transmissions,
+                                    sequence_number);
+    }
+  }
+
+  // Two cases for MarkPacketHandled:
+  // 1) Handle the most recent or a crypto packet, so remove all transmissions.
+  // 2) Handle old transmission, keep all other pending transmissions,
+  //    but disassociate them from one another.
+
+  // If it's a crypto handshake packet, discard it and all retransmissions,
+  // since they won't be acked now that one has been processed.
+  // TODO(ianswett): Instead of handling all crypto packets in a special way,
+  // only handle NULL encrypted packets in a special way.
+  if (HasCryptoHandshake(
+          unacked_packets_.GetTransmissionInfo(newest_transmission))) {
+    unacked_packets_.RemoveFromInFlight(newest_transmission);
+  }
   unacked_packets_.RemoveFromInFlight(sequence_number);
   unacked_packets_.RemoveRetransmittability(sequence_number);
+
+  QuicUnackedPacketMap::const_iterator next_unacked = unacked_packets_.begin();
+  while (next_unacked != unacked_packets_.end() &&
+         next_unacked->first <= sequence_number) {
+    ++next_unacked;
+  }
+  return next_unacked;
 }
 
 bool QuicSentPacketManager::IsUnacked(
@@ -495,7 +513,7 @@
 
 QuicPacketSequenceNumber
 QuicSentPacketManager::GetLeastUnackedSentPacket() const {
-  return unacked_packets_.GetLeastUnacked();
+  return unacked_packets_.GetLeastUnackedSentPacket();
 }
 
 bool QuicSentPacketManager::OnPacketSent(
@@ -529,8 +547,7 @@
   unacked_packets_.SetSent(sequence_number, sent_time, bytes, in_flight);
 
   if (debug_delegate_ != NULL) {
-    debug_delegate_->OnSentPacket(
-        sequence_number, sent_time, bytes, transmission_type);
+    debug_delegate_->OnSentPacket(sequence_number, sent_time, bytes);
   }
 
   // Reset the retransmission timer anytime a pending packet is sent.
@@ -580,12 +597,13 @@
       min(kMaxHandshakeRetransmissionBackoffs,
           consecutive_crypto_retransmission_count_ + 1);
   bool packet_retransmitted = false;
-  QuicPacketSequenceNumber sequence_number = unacked_packets_.GetLeastUnacked();
   for (QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
-       it != unacked_packets_.end(); ++it, ++sequence_number) {
+       it != unacked_packets_.end(); ++it) {
+    QuicPacketSequenceNumber sequence_number = it->first;
+    const RetransmittableFrames* frames = it->second.retransmittable_frames;
     // Only retransmit frames which are in flight, and therefore have been sent.
-    if (!it->in_flight || it->retransmittable_frames == NULL ||
-        it->retransmittable_frames->HasCryptoHandshake() != IS_HANDSHAKE) {
+    if (!it->second.in_flight || frames == NULL ||
+        frames->HasCryptoHandshake() != IS_HANDSHAKE) {
       continue;
     }
     packet_retransmitted = true;
@@ -599,15 +617,16 @@
   if (pending_timer_transmission_count_ == 0) {
     return false;
   }
-  QuicPacketSequenceNumber sequence_number = unacked_packets_.GetLeastUnacked();
   for (QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
-       it != unacked_packets_.end(); ++it, ++sequence_number) {
+       it != unacked_packets_.end(); ++it) {
+    QuicPacketSequenceNumber sequence_number = it->first;
+    const RetransmittableFrames* frames = it->second.retransmittable_frames;
     // Only retransmit frames which are in flight, and therefore have been sent.
-    if (!it->in_flight || it->retransmittable_frames == NULL) {
+    if (!it->second.in_flight || frames == NULL) {
       continue;
     }
     if (!handshake_confirmed_) {
-      DCHECK_NE(IS_HANDSHAKE, it->retransmittable_frames->HasCryptoHandshake());
+      DCHECK_NE(IS_HANDSHAKE, frames->HasCryptoHandshake());
     }
     MarkForRetransmission(sequence_number, TLP_RETRANSMISSION);
     return true;
@@ -619,17 +638,18 @@
 
 void QuicSentPacketManager::RetransmitAllPackets() {
   DVLOG(1) << "RetransmitAllPackets() called with "
-           << unacked_packets_.GetNumUnackedPacketsDebugOnly()
-           << " unacked packets.";
+           << unacked_packets_.GetNumUnackedPackets() << " unacked packets.";
   // Request retransmission of all retransmittable packets when the RTO
   // fires, and let the congestion manager decide how many to send
   // immediately and the remaining packets will be queued.
   // Abandon any non-retransmittable packets that are sufficiently old.
   bool packets_retransmitted = false;
-  QuicPacketSequenceNumber sequence_number = unacked_packets_.GetLeastUnacked();
-  for (QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
-       it != unacked_packets_.end(); ++it, ++sequence_number) {
-    if (it->retransmittable_frames != NULL) {
+  QuicUnackedPacketMap::const_iterator it = unacked_packets_.begin();
+  while (it != unacked_packets_.end()) {
+    const RetransmittableFrames* frames = it->second.retransmittable_frames;
+    QuicPacketSequenceNumber sequence_number = it->first;
+    ++it;
+    if (frames != NULL) {
       packets_retransmitted = true;
       MarkForRetransmission(sequence_number, RTO_RETRANSMISSION);
     } else {