Home | History | Annotate | Download | only in quic 
      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 //
      5 // Manages the packet entropy calculation for both sent and received packets
      6 // for a connection.
      7 
      8 #ifndef NET_QUIC_QUIC_RECEIVED_PACKET_MANAGER_H_
      9 #define NET_QUIC_QUIC_RECEIVED_PACKET_MANAGER_H_
     10 
     11 #include "net/quic/quic_framer.h"
     12 #include "net/quic/quic_protocol.h"
     13 
     14 namespace net {
     15 
     16 namespace test {
     17 class QuicReceivedPacketManagerPeer;
     18 }  // namespace test
     19 
     20 // Records all received packets by a connection and tracks their entropy.
     21 // Also calculates the correct entropy for the framer when it truncates an ack
     22 // frame being serialized.
     23 class NET_EXPORT_PRIVATE QuicReceivedPacketManager :
     24     public QuicReceivedEntropyHashCalculatorInterface {
     25  public:
     26   QuicReceivedPacketManager();
     27   virtual ~QuicReceivedPacketManager();
     28 
     29   // Updates the internal state concerning which packets have been acked.
     30   void RecordPacketReceived(const QuicPacketHeader& header,
     31                             QuicTime receipt_time);
     32 
     33   // Checks if we're still waiting for the packet with |sequence_number|.
     34   bool IsAwaitingPacket(QuicPacketSequenceNumber sequence_number);
     35 
     36   // Update the |received_info| for an outgoing ack.
     37   void UpdateReceivedPacketInfo(ReceivedPacketInfo* received_info,
     38                                 QuicTime approximate_now);
     39 
     40   // QuicReceivedEntropyHashCalculatorInterface
     41   // Called by QuicFramer, when the outgoing ack gets truncated, to recalculate
     42   // the received entropy hash for the truncated ack frame.
     43   virtual QuicPacketEntropyHash EntropyHash(
     44       QuicPacketSequenceNumber sequence_number) const OVERRIDE;
     45 
     46   // These two are called by OnAckFrame.
     47   //
     48   // Updates internal state based on |incoming_ack.received_info|.
     49   void UpdatePacketInformationReceivedByPeer(const QuicAckFrame& incoming_ack);
     50   // Updates internal state based on |incoming_ack.sent_info|.
     51   void UpdatePacketInformationSentByPeer(const QuicAckFrame& incoming_ack);
     52 
     53   QuicPacketSequenceNumber peer_largest_observed_packet() {
     54     return peer_largest_observed_packet_;
     55   }
     56 
     57   QuicPacketSequenceNumber least_packet_awaited_by_peer() {
     58     return least_packet_awaited_by_peer_;
     59   }
     60 
     61   QuicPacketSequenceNumber peer_least_packet_awaiting_ack() {
     62     return peer_least_packet_awaiting_ack_;
     63   }
     64 
     65  private:
     66   friend class test::QuicReceivedPacketManagerPeer;
     67 
     68   typedef std::map<QuicPacketSequenceNumber,
     69                    QuicPacketEntropyHash> ReceivedEntropyMap;
     70 
     71   // Record the received entropy hash against |sequence_number|.
     72   void RecordPacketEntropyHash(QuicPacketSequenceNumber sequence_number,
     73                                QuicPacketEntropyHash entropy_hash);
     74 
     75   // Recalculate the entropy hash and clears old packet entropies,
     76   // now that the sender sent us the |entropy_hash| for packets up to,
     77   // but not including, |peer_least_unacked|.
     78   void RecalculateEntropyHash(QuicPacketSequenceNumber peer_least_unacked,
     79                               QuicPacketEntropyHash entropy_hash);
     80 
     81   // Deletes all missing packets before least unacked. The connection won't
     82   // process any packets with sequence number before |least_unacked| that it
     83   // received after this call. Returns true if there were missing packets before
     84   // |least_unacked| unacked, false otherwise.
     85   bool DontWaitForPacketsBefore(QuicPacketSequenceNumber least_unacked);
     86 
     87   // TODO(satyamshekhar): Can be optimized using an interval set like data
     88   // structure.
     89   // Map of received sequence numbers to their corresponding entropy.
     90   // Every received packet has an entry, and packets without the entropy bit set
     91   // have an entropy value of 0.
     92   // TODO(ianswett): When the entropy flag is off, the entropy should not be 0.
     93   ReceivedEntropyMap packets_entropy_;
     94 
     95   // Cumulative hash of entropy of all received packets.
     96   QuicPacketEntropyHash packets_entropy_hash_;
     97 
     98   // The largest sequence number cleared by RecalculateEntropyHash.
     99   // Received entropy cannot be calculated for numbers less than it.
    100   QuicPacketSequenceNumber largest_sequence_number_;
    101 
    102 
    103   // Track some peer state so we can do less bookkeeping.
    104   // Largest sequence number that the peer has observed. Mostly received,
    105   // missing in case of truncated acks.
    106   QuicPacketSequenceNumber peer_largest_observed_packet_;
    107   // Least sequence number which the peer is still waiting for.
    108   QuicPacketSequenceNumber least_packet_awaited_by_peer_;
    109   // Least sequence number of the the packet sent by the peer for which it
    110   // hasn't received an ack.
    111   QuicPacketSequenceNumber peer_least_packet_awaiting_ack_;
    112 
    113   // Received packet information used to produce acks.
    114   ReceivedPacketInfo received_info_;
    115 
    116   // The time we received the largest_observed sequence number, or zero if
    117   // no sequence numbers have been received since UpdateReceivedPacketInfo.
    118   // Needed for calculating delta_time_largest_observed.
    119   QuicTime time_largest_observed_;
    120 };
    121 
    122 }  // namespace net
    123 
    124 #endif  // NET_QUIC_QUIC_RECEIVED_PACKET_MANAGER_H_
    125