Fix the semantics of QuicFecGroup::ProtectsPacketsBefore into IsWaitingForPacketBefore. Certain ed…

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"
@@ skipping 100 matching lines @@
     decrypted_payload[i] = payload_parity_[i];
   }
 
   header->packet_number = missing;
   header->entropy_flag = false;  // Unknown entropy.
 
   received_packets_.insert(missing);
   return payload_parity_len_;
 }
 
-bool QuicFecGroup::ProtectsPacketsBefore(QuicPacketNumber num) const {
-  if (has_received_fec_packet()) {
-    return max_protected_packet_ < num;
+bool QuicFecGroup::IsWaitingForPacketBefore(QuicPacketNumber num) const {
+  // Entire range is larger than the threshold.
+  if (min_protected_packet_ >= num) {
+    return false;
   }
-  // Since we might not yet have received the FEC packet, we must check
-  // the packets we have received.
-  return *received_packets_.begin() < num;
+
+  // Entire range is smaller than the threshold.
+  if (received_packets_.size() > 0 ? *received_packets_.rbegin() + 1 < num
+                                   : min_protected_packet_ < num) {
+    return true;
+  }
+
+  // Range spans the threshold so look for a missing packet below the threshold.
+  QuicPacketNumber target = min_protected_packet_;
+  for (QuicPacketNumber packet : received_packets_) {
+    if (target++ != packet) {
+      return true;
+    }
+    if (target >= num) {
+      return false;
+    }
+  }
+
+  // No missing packets below the threshold.
+  return false;
 }
 
 bool QuicFecGroup::UpdateParity(StringPiece payload) {
   DCHECK_GE(kMaxPacketSize, payload.size());
   if (payload.size() > kMaxPacketSize) {
     DLOG(ERROR) << "Illegal payload size: " << payload.size();
     return false;
   }
   if (payload_parity_len_ < payload.size()) {
     payload_parity_len_ = payload.size();
@@ skipping 32 matching lines @@
 
 QuicPacketCount QuicFecGroup::NumReceivedPackets() const {
   return received_packets_.size();
 }
 
 EncryptionLevel QuicFecGroup::EffectiveEncryptionLevel() const {
   return effective_encryption_level_;
 }
 
 }  // namespace net