Remove parity tracking in FEC groups as part of the migration to

net/quic/quic_fec_group.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_fec_group.h"
 
 #include <limits>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 
 using base::StringPiece;
 using std::numeric_limits;
 using std::set;
 
 namespace net {
 
 namespace {
 const QuicPacketSequenceNumber kNoSequenceNumber = kuint64max;
 }  // namespace
 
 QuicFecGroup::QuicFecGroup()
     : min_protected_packet_(kNoSequenceNumber),
       max_protected_packet_(kNoSequenceNumber),
-      payload_parity_len_(0),
-      entropy_parity_(false) {
+      payload_parity_len_(0) {
 }
 
 QuicFecGroup::~QuicFecGroup() {}
 
 bool QuicFecGroup::Update(const QuicPacketHeader& header,
                           StringPiece decrypted_payload) {
   if (received_packets_.count(header.packet_sequence_number) != 0) {
     return false;
   }
   if (min_protected_packet_ != kNoSequenceNumber &&
       max_protected_packet_ != kNoSequenceNumber &&
       (header.packet_sequence_number < min_protected_packet_ ||
        header.packet_sequence_number > max_protected_packet_)) {
     DLOG(ERROR) << "FEC group does not cover received packet: "
                 << header.packet_sequence_number;
     return false;
   }
-  if (!UpdateParity(decrypted_payload, header.entropy_flag)) {
+  if (!UpdateParity(decrypted_payload)) {
     return false;
   }
   received_packets_.insert(header.packet_sequence_number);
   return true;
 }
 
 bool QuicFecGroup::UpdateFec(
     QuicPacketSequenceNumber fec_packet_sequence_number,
-    bool fec_packet_entropy,
     const QuicFecData& fec) {
   if (min_protected_packet_ != kNoSequenceNumber) {
     return false;
   }
   SequenceNumberSet::const_iterator it = received_packets_.begin();
   while (it != received_packets_.end()) {
-    if ((*it < fec.fec_group) ||
-        (*it >= fec_packet_sequence_number)) {
+    if ((*it < fec.fec_group) || (*it >= fec_packet_sequence_number)) {
       DLOG(ERROR) << "FEC group does not cover received packet: " << *it;
       return false;
     }
     ++it;
   }
-  if (!UpdateParity(fec.redundancy, fec_packet_entropy)) {
+  if (!UpdateParity(fec.redundancy)) {
     return false;
   }
   min_protected_packet_ = fec.fec_group;
   max_protected_packet_ = fec_packet_sequence_number - 1;
   return true;
 }
 
 bool QuicFecGroup::CanRevive() const {
   // We can revive if we're missing exactly 1 packet.
   return NumMissingPackets() == 1;
@@ skipping 25 matching lines @@
 
   DCHECK_LE(payload_parity_len_, decrypted_payload_len);
   if (payload_parity_len_ > decrypted_payload_len) {
     return 0;
   }
   for (size_t i = 0; i < payload_parity_len_; ++i) {
     decrypted_payload[i] = payload_parity_[i];
   }
 
   header->packet_sequence_number = missing;
-  header->entropy_flag = entropy_parity_;
+  header->entropy_flag = 0;  // Unknown entropy.
 
   received_packets_.insert(missing);
   return payload_parity_len_;
 }
 
 bool QuicFecGroup::ProtectsPacketsBefore(QuicPacketSequenceNumber num) const {
   if (max_protected_packet_ != kNoSequenceNumber) {
     return max_protected_packet_ < num;
   }
   // Since we might not yet have recevied the FEC packet, we must check
   // the packets we have received.
   return *received_packets_.begin() < num;
 }
 
-bool QuicFecGroup::UpdateParity(StringPiece payload, bool entropy) {
+bool QuicFecGroup::UpdateParity(StringPiece payload) {
   DCHECK_LE(payload.size(), kMaxPacketSize);
   if (payload.size() > kMaxPacketSize) {
     DLOG(ERROR) << "Illegal payload size: " << payload.size();
     return false;
   }
   if (payload_parity_len_ < payload.size()) {
     payload_parity_len_ = payload.size();
   }
   DCHECK_LE(payload.size(), kMaxPacketSize);
   if (received_packets_.empty() &&
       min_protected_packet_ == kNoSequenceNumber) {
     // Initialize the parity to the value of this payload
     memcpy(payload_parity_, payload.data(), payload.size());
     if (payload.size() < kMaxPacketSize) {
       // TODO(rch): expand as needed.
       memset(payload_parity_ + payload.size(), 0,
              kMaxPacketSize - payload.size());
     }
-    entropy_parity_ = entropy;
     return true;
   }
   // Update the parity by XORing in the data (padding with 0s if necessary).
   for (size_t i = 0; i < kMaxPacketSize; ++i) {
     uint8 byte = i < payload.size() ? payload[i] : 0x00;
     payload_parity_[i] ^= byte;
   }
-  // xor of boolean values.
-  entropy_parity_ = (entropy_parity_ != entropy);
   return true;
 }
 
 size_t QuicFecGroup::NumMissingPackets() const {
   if (min_protected_packet_ == kNoSequenceNumber)
     return numeric_limits<size_t>::max();
   return (max_protected_packet_ - min_protected_packet_ + 1) -
       received_packets_.size();
 }
 
 }  // namespace net