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// Copyright 2014 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 <deque>
#include "net/quic/quic_protocol.h"
namespace net {
class AckNotifierManager;
// Class which tracks unacked packets for three purposes:
// 1) Track retransmittable data, including multiple transmissions of frames.
// 2) Track packets and bytes in flight for congestion control.
// 3) Track sent time of packets to provide RTT measurements from acks.
class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
// Initialize an instance of UnackedPacketMap. The AckNotifierManager
// provided to the constructor will be notified whenever a packet is removed
// from the map.
explicit QuicUnackedPacketMap(AckNotifierManager* ack_notifier_manager);
// Adds |serialized_packet| to the map and marks it as sent at |sent_time|.
// Marks the packet as in flight if |set_in_flight| is true.
// Packets marked as in flight are expected to be marked as missing when they
// don't arrive, indicating the need for retransmission.
// |old_sequence_number| is the sequence number of the previous transmission,
// or 0 if there was none.
void AddSentPacket(const SerializedPacket& serialized_packet,
QuicPacketSequenceNumber old_sequence_number,
TransmissionType transmission_type,
QuicTime sent_time,
QuicByteCount bytes_sent,
bool set_in_flight);
// Returns true if the packet |sequence_number| is unacked.
bool IsUnacked(QuicPacketSequenceNumber sequence_number) const;
// Sets the nack count to the max of the current nack count and |min_nacks|.
void NackPacket(QuicPacketSequenceNumber sequence_number,
QuicPacketCount min_nacks);
// Marks |sequence_number| as no longer in flight.
void RemoveFromInFlight(QuicPacketSequenceNumber sequence_number);
// No longer retransmit data for |stream_id|.
void CancelRetransmissionsForStream(QuicStreamId stream_id);
// Returns true if the unacked packet |sequence_number| has retransmittable
// frames. This will return false if the packet has been acked, if a
// previous transmission of this packet was ACK'd, or if this packet has been
// retransmitted as with different sequence number, or if the packet never
// had any retransmittable packets in the first place.
bool HasRetransmittableFrames(QuicPacketSequenceNumber sequence_number) const;
// Returns true if there are any unacked packets.
bool HasUnackedPackets() const;
// Returns true if there are any unacked packets which have retransmittable
// frames.
bool HasUnackedRetransmittableFrames() const;
// Returns the largest sequence number that has been sent.
QuicPacketSequenceNumber largest_sent_packet() const {
return largest_sent_packet_;
// Returns the largest sequence number that has been acked.
QuicPacketSequenceNumber largest_observed() const {
return largest_observed_;
// Returns the sum of bytes from all packets in flight.
QuicByteCount bytes_in_flight() const {
return bytes_in_flight_;
// Returns the smallest sequence number of a serialized packet which has not
// been acked by the peer. If there are no unacked packets, returns 0.
QuicPacketSequenceNumber GetLeastUnacked() const;
// Clears all previous transmissions in order to make room in the ack frame
// for newly acked packets.
void ClearAllPreviousRetransmissions();
typedef std::deque<TransmissionInfo> UnackedPacketMap;
typedef UnackedPacketMap::const_iterator const_iterator;
const_iterator begin() const { return unacked_packets_.begin(); }
const_iterator end() const { return unacked_packets_.end(); }
// Returns true if there are unacked packets that are in flight.
bool HasInFlightPackets() const;
// Returns the TransmissionInfo associated with |sequence_number|, which
// must be unacked.
const TransmissionInfo& GetTransmissionInfo(
QuicPacketSequenceNumber sequence_number) const;
// Returns the time that the last unacked packet was sent.
QuicTime GetLastPacketSentTime() const;
// Returns the number of unacked packets.
size_t GetNumUnackedPacketsDebugOnly() const;
// Returns true if there are multiple packets in flight.
bool HasMultipleInFlightPackets() const;
// Returns true if there are any pending crypto packets.
bool HasPendingCryptoPackets() const;
// Removes any retransmittable frames from this transmission or an associated
// transmission. It removes now useless transmissions, and disconnects any
// other packets from other transmissions.
void RemoveRetransmittability(QuicPacketSequenceNumber sequence_number);
// Removes any other retransmissions and marks all transmissions unackable.
void RemoveAckability(TransmissionInfo* info);
// Increases the largest observed. Any packets less or equal to
// |largest_acked_packet| are discarded if they are only for the RTT purposes.
void IncreaseLargestObserved(QuicPacketSequenceNumber largest_observed);
// Remove any packets no longer needed for retransmission, congestion, or
// RTT measurement purposes.
void RemoveObsoletePackets();
// Called when a packet is retransmitted with a new sequence number.
// |old_sequence_number| will remain unacked, but will have no
// retransmittable data associated with it. Retransmittable frames will be
// transferred to |info| and all_transmissions will be populated.
void TransferRetransmissionInfo(QuicPacketSequenceNumber old_sequence_number,
QuicPacketSequenceNumber new_sequence_number,
TransmissionType transmission_type,
TransmissionInfo* info);
void MaybeRemoveRetransmittableFrames(TransmissionInfo* transmission_info);
// Returns true if packet may be useful for an RTT measurement.
bool IsPacketUsefulForMeasuringRtt(QuicPacketSequenceNumber sequence_number,
const TransmissionInfo& info) const;
// Returns true if packet may be useful for congestion control purposes.
bool IsPacketUsefulForCongestionControl(const TransmissionInfo& info) const;
// Returns true if packet may be associated with retransmittable data
// directly or through retransmissions.
bool IsPacketUsefulForRetransmittableData(const TransmissionInfo& info) const;
// Returns true if the packet no longer has a purpose in the map.
bool IsPacketUseless(QuicPacketSequenceNumber sequence_number,
const TransmissionInfo& info) const;
// Removes the packet with lowest sequence number from the map.
void PopLeastUnacked();
QuicPacketSequenceNumber largest_sent_packet_;
QuicPacketSequenceNumber largest_observed_;
// Newly serialized retransmittable and fec packets are added to this map,
// which contains owning pointers to any contained frames. If a packet is
// retransmitted, this map will contain entries for both the old and the new
// packet. The old packet's retransmittable frames entry will be nullptr,
// while the new packet's entry will contain the frames to retransmit.
// If the old packet is acked before the new packet, then the old entry will
// be removed from the map and the new entry's retransmittable frames will be
// set to nullptr.
UnackedPacketMap unacked_packets_;
// The packet at the 0th index of unacked_packets_.
QuicPacketSequenceNumber least_unacked_;
QuicByteCount bytes_in_flight_;
// Number of retransmittable crypto handshake packets.
size_t pending_crypto_packet_count_;
// Notifier manager for ACK packets. We notify it every time we abandon a
// packet.
AckNotifierManager* ack_notifier_manager_;
} // namespace net