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// Copyright 2015 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 <algorithm>
#include <map>
#include "base/macros.h"
#include "net/third_party/quiche/src/quic/core/congestion_control/loss_detection_interface.h"
#include "net/third_party/quiche/src/quic/core/quic_packets.h"
#include "net/third_party/quiche/src/quic/core/quic_time.h"
#include "net/third_party/quiche/src/quic/core/quic_unacked_packet_map.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
namespace quic {
// Class which can be configured to implement's TCP's approach of detecting loss
// when 3 nacks have been received for a packet or with a time threshold.
// Also implements TCP's early retransmit(RFC5827).
class QUIC_EXPORT_PRIVATE GeneralLossAlgorithm : public LossDetectionInterface {
// TCP retransmits after 3 nacks.
static const QuicPacketCount kNumberOfNacksBeforeRetransmission = 3;
explicit GeneralLossAlgorithm(LossDetectionType loss_type);
GeneralLossAlgorithm(const GeneralLossAlgorithm&) = delete;
GeneralLossAlgorithm& operator=(const GeneralLossAlgorithm&) = delete;
~GeneralLossAlgorithm() override {}
LossDetectionType GetLossDetectionType() const override;
// Switches the loss detection type to |loss_type| and resets the loss
// algorithm.
void SetLossDetectionType(LossDetectionType loss_type);
// Uses |largest_acked| and time to decide when packets are lost.
void DetectLosses(const QuicUnackedPacketMap& unacked_packets,
QuicTime time,
const RttStats& rtt_stats,
QuicPacketNumber largest_newly_acked,
const AckedPacketVector& packets_acked,
LostPacketVector* packets_lost) override;
// Returns a non-zero value when the early retransmit timer is active.
QuicTime GetLossTimeout() const override;
// Increases the loss detection threshold for time loss detection.
void SpuriousRetransmitDetected(
const QuicUnackedPacketMap& unacked_packets,
QuicTime time,
const RttStats& rtt_stats,
QuicPacketNumber spurious_retransmission) override;
void SetPacketNumberSpace(PacketNumberSpace packet_number_space);
int reordering_shift() const { return reordering_shift_; }
QuicTime loss_detection_timeout_;
// Largest sent packet when a spurious retransmit is detected.
// Prevents increasing the reordering threshold multiple times per epoch.
// TODO(ianswett): Deprecate when quic_fix_adaptive_time_loss flag is
// deprecated.
QuicPacketNumber largest_sent_on_spurious_retransmit_;
LossDetectionType loss_type_;
// Fraction of a max(SRTT, latest_rtt) to permit reordering before declaring
// loss. Fraction calculated by shifting max(SRTT, latest_rtt) to the right
// by reordering_shift.
int reordering_shift_;
// The largest newly acked from the previous call to DetectLosses.
QuicPacketNumber largest_previously_acked_;
// The least in flight packet. Loss detection should start from this. Please
// note, least_in_flight_ could be largest packet ever sent + 1.
QuicPacketNumber least_in_flight_;
// This is only used when quic_use_uber_loss_algorithm is true.
PacketNumberSpace packet_number_space_;
} // namespace quic