Ton

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/*
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    This file is part of TON Blockchain Library.
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    TON Blockchain Library is free software: you can redistribute it and/or modify
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    it under the terms of the GNU Lesser General Public License as published by
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    the Free Software Foundation, either version 2 of the License, or
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    (at your option) any later version.
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    TON Blockchain Library is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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    GNU Lesser General Public License for more details.
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    You should have received a copy of the GNU Lesser General Public License
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    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
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    Copyright 2017-2020 Telegram Systems LLP
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*/
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#include "SenderPackets.h"
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#include "td/utils/bits.h"
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namespace ton {
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namespace rldp2 {
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td::uint32 SenderPackets::next_seqno() const {
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  return last_seqno_ + 1;
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}
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SenderPackets::DropUpdate SenderPackets::drop_packets(const Limits &limits) {
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  while (!packets.empty()) {
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    auto &packet = packets.front();
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    if (!limits.should_drop(packet)) {
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      break;
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    }
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    mark_ack_or_lost(packet);
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    packets.pop();
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  }
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  DropUpdate update;
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  update.new_ack = total_ack_ - last_total_ack_;
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  update.new_lost = total_lost_ - last_total_lost_;
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  last_total_ack_ = total_ack_;
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  last_total_lost_ = total_lost_;
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  update.o_loss_at = std::move(last_loss_);
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  return update;
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}
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SenderPackets::Update SenderPackets::on_ack(Ack ack) {
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  ack.max_seqno = td::min(ack.max_seqno, last_seqno_);
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  ack.received_count = td::min(ack.received_count, ack.max_seqno);
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  // TODO: seqno of rldp and seqno of a packet must be completly separate seqnos
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  Update update;
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  if (received_count_ < ack.received_count) {
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    update.new_received = ack.received_count - received_count_;
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    left_ack_ += update.new_received;
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    left_ack_ = td::min(left_ack_, in_flight_count_);
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    received_count_ = ack.received_count;
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  }
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  if (max_packet_.seqno > ack.max_seqno) {
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    return update;
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  }
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  auto packet = get_packet(ack.max_seqno);
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  if (!packet) {
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    return update;
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  }
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  if (max_packet_.seqno < ack.max_seqno) {
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    update.was_max_updated = true;
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    max_packet_ = *packet;
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  }
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  for (td::uint32 i : td::BitsRange(ack.received_mask)) {
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    if (ack.max_seqno < i) {
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      break;
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    }
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    auto seqno = ack.max_seqno - i;
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    auto packet = get_packet(seqno);
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    if (!packet) {
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      break;
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    }
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    mark_ack(*packet);
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  }
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  return update;
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}
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void SenderPackets::mark_ack_or_lost(Packet &packet) {
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  if (left_ack_) {
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    mark_ack(packet);
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  } else {
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    mark_lost(packet);
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  }
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}
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void SenderPackets::mark_lost(Packet &packet) {
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  if (!packet.is_in_flight) {
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    return;
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  }
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  total_lost_++;
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  in_flight_count_--;
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  packet.is_in_flight = false;
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  last_loss_ = packet.sent_at;
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}
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void SenderPackets::mark_ack(Packet &packet) {
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  if (!packet.is_in_flight) {
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    return;
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  }
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  if (left_ack_ > 0) {
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    left_ack_--;
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  }
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  total_ack_++;
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  in_flight_count_--;
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  packet.is_in_flight = false;
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}
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SenderPackets::Packet *SenderPackets::get_packet(td::uint32 seqno) {
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  if (packets.empty()) {
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    return nullptr;
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  }
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  auto front_seqno = packets.front().seqno;
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  if (front_seqno > seqno) {
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    return nullptr;
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  }
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  td::uint32 index = seqno - front_seqno;
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  if (index >= packets.size()) {
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    return nullptr;
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  }
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  auto packet = packets.data() + index;
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  CHECK(packet->seqno == seqno);
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  return packet;
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}
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void SenderPackets::send(Packet packet) {
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  CHECK(next_seqno() == packet.seqno);
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  packets.push(packet);
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  last_seqno_++;
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  in_flight_count_ += packet.is_in_flight;
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}
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}  // namespace rldp2
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}  // namespace ton
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