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/*
* Copyright (c) 2021 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <glog/logging.h>
#include <protocols/rtc/rtc_consts.h>
#include <protocols/rtc/rtc_ldr.h>
#include <protocols/rtc/rtc_rs_delay.h>
#include <protocols/rtc/rtc_rs_fec_only.h>
#include <protocols/rtc/rtc_rs_low_rate.h>
#include <protocols/rtc/rtc_rs_recovery_off.h>
#include <protocols/rtc/rtc_rs_rtx_only.h>
#include <protocols/rtc/rtc_state.h>
#include <algorithm>
#include <unordered_set>
namespace transport {
namespace protocol {
namespace rtc {
RTCLossDetectionAndRecovery::RTCLossDetectionAndRecovery(
Indexer *indexer, asio::io_service &io_service,
interface::RtcTransportRecoveryStrategies type,
RecoveryStrategy::SendRtxCallback &&callback,
interface::StrategyCallback &&external_callback) {
if (type == interface::RtcTransportRecoveryStrategies::RECOVERY_OFF) {
rs_ = std::make_shared<RecoveryStrategyRecoveryOff>(
indexer, std::move(callback), io_service, type,
std::move(external_callback));
} else if (type == interface::RtcTransportRecoveryStrategies::DELAY_BASED ||
type == interface::RtcTransportRecoveryStrategies::
DELAY_AND_BESTPATH ||
type == interface::RtcTransportRecoveryStrategies::
DELAY_AND_REPLICATION) {
rs_ = std::make_shared<RecoveryStrategyDelayBased>(
indexer, std::move(callback), io_service, type,
std::move(external_callback));
} else if (type == interface::RtcTransportRecoveryStrategies::FEC_ONLY ||
type == interface::RtcTransportRecoveryStrategies::
FEC_ONLY_LOW_RES_LOSSES) {
rs_ = std::make_shared<RecoveryStrategyFecOnly>(
indexer, std::move(callback), io_service, type,
std::move(external_callback));
} else if (type == interface::RtcTransportRecoveryStrategies::LOW_RATE ||
type == interface::RtcTransportRecoveryStrategies::
LOW_RATE_AND_BESTPATH ||
type == interface::RtcTransportRecoveryStrategies::
LOW_RATE_AND_REPLICATION ||
type == interface::RtcTransportRecoveryStrategies::
LOW_RATE_AND_ALL_FWD_STRATEGIES) {
rs_ = std::make_shared<RecoveryStrategyLowRate>(
indexer, std::move(callback), io_service, type,
std::move(external_callback));
} else {
// default
type = interface::RtcTransportRecoveryStrategies::RTX_ONLY;
rs_ = std::make_shared<RecoveryStrategyRtxOnly>(
indexer, std::move(callback), io_service, type,
std::move(external_callback));
}
}
RTCLossDetectionAndRecovery::~RTCLossDetectionAndRecovery() {}
void RTCLossDetectionAndRecovery::changeRecoveryStrategy(
interface::RtcTransportRecoveryStrategies type) {
if (type == rs_->getType()) return;
rs_->updateType(type);
if (type == interface::RtcTransportRecoveryStrategies::RECOVERY_OFF) {
rs_ =
std::make_shared<RecoveryStrategyRecoveryOff>(std::move(*(rs_.get())));
} else if (type == interface::RtcTransportRecoveryStrategies::DELAY_BASED ||
type == interface::RtcTransportRecoveryStrategies::
DELAY_AND_BESTPATH ||
type == interface::RtcTransportRecoveryStrategies::
DELAY_AND_REPLICATION) {
rs_ = std::make_shared<RecoveryStrategyDelayBased>(std::move(*(rs_.get())));
} else if (type == interface::RtcTransportRecoveryStrategies::FEC_ONLY ||
type == interface::RtcTransportRecoveryStrategies::
FEC_ONLY_LOW_RES_LOSSES) {
rs_ = std::make_shared<RecoveryStrategyFecOnly>(std::move(*(rs_.get())));
} else if (type == interface::RtcTransportRecoveryStrategies::LOW_RATE ||
type == interface::RtcTransportRecoveryStrategies::
LOW_RATE_AND_BESTPATH ||
type == interface::RtcTransportRecoveryStrategies::
LOW_RATE_AND_REPLICATION ||
type == interface::RtcTransportRecoveryStrategies::
LOW_RATE_AND_ALL_FWD_STRATEGIES) {
rs_ = std::make_shared<RecoveryStrategyLowRate>(std::move(*(rs_.get())));
} else {
// default
rs_ = std::make_shared<RecoveryStrategyRtxOnly>(std::move(*(rs_.get())));
}
}
void RTCLossDetectionAndRecovery::onNewRound(bool in_sync) {
rs_->incRoundId();
rs_->onNewRound(in_sync);
}
bool RTCLossDetectionAndRecovery::onTimeout(uint32_t seq, bool lost) {
if (!lost) {
return detectLoss(seq, seq + 1, false);
} else {
rs_->onLostTimeout(seq);
}
return false;
}
bool RTCLossDetectionAndRecovery::onPacketRecoveredFec(uint32_t seq) {
rs_->receivedPacket(seq);
return false;
}
bool RTCLossDetectionAndRecovery::onDataPacketReceived(
const core::ContentObject &content_object) {
uint32_t seq = content_object.getName().getSuffix();
bool is_rtx = rs_->isRtx(seq);
rs_->receivedPacket(seq);
bool ret = false;
DLOG_IF(INFO, VLOG_IS_ON(3))
<< "received data. add from "
<< rs_->getState()->getHighestSeqReceived() + 1 << " to " << seq;
if (!is_rtx)
ret = detectLoss(rs_->getState()->getHighestSeqReceived() + 1, seq, false);
rs_->getState()->updateHighestSeqReceived(seq);
return ret;
}
bool RTCLossDetectionAndRecovery::onNackPacketReceived(
const core::ContentObject &nack) {
struct nack_packet_t *nack_pkt =
(struct nack_packet_t *)nack.getPayload()->data();
uint32_t production_seq = nack_pkt->getProductionSegment();
uint32_t seq = nack.getName().getSuffix();
// received a nack. we can try to recover all data packets between the last
// received data and the production seq in the nack. this is similar to the
// recption of a probe
// e.g.: the client receives packets 10 11 12 20 where 20 is a nack
// with productionSeq = 18. this says that all the packets between 12 and 18
// may got lost and we should ask them
rs_->receivedPacket(seq);
DLOG_IF(INFO, VLOG_IS_ON(3)) << "received nack. add from "
<< rs_->getState()->getHighestSeqReceived() + 1
<< " to " << production_seq;
// if it is a future nack store it in the list set of nacked seq
if (production_seq <= seq) rs_->receivedFutureNack(seq);
// call the detectLoss function using the probe flag = true. in fact the
// losses detected using nacks are the same as the one detected using probes,
// we should not increase the loss counter
return detectLoss(rs_->getState()->getHighestSeqReceived() + 1,
production_seq, true);
}
bool RTCLossDetectionAndRecovery::onProbePacketReceived(
const core::ContentObject &probe) {
// we don't log the reception of a probe packet for the sentinel timer because
// probes are not taken into account into the sync window. we use them as
// future nacks to detect possible packets lost
uint32_t production_seq = RTCState::getProbeParams(probe).prod_seg;
DLOG_IF(INFO, VLOG_IS_ON(3)) << "received probe. add from "
<< rs_->getState()->getHighestSeqReceived() + 1
<< " to " << production_seq;
return detectLoss(rs_->getState()->getHighestSeqReceived() + 1,
production_seq, true);
}
bool RTCLossDetectionAndRecovery::detectLoss(uint32_t start, uint32_t stop,
bool recv_probe) {
if (start >= stop) return false;
// skip nacked packets
if (start <= rs_->getState()->getLastSeqNacked()) {
start = rs_->getState()->getLastSeqNacked() + 1;
}
// skip received or lost packets
if (start <= rs_->getState()->getHighestSeqReceived()) {
start = rs_->getState()->getHighestSeqReceived() + 1;
}
bool loss_detected = false;
for (uint32_t seq = start; seq < stop; seq++) {
if (rs_->getState()->getPacketState(seq) == PacketState::UNKNOWN) {
if (rs_->lossDetected(seq)) {
loss_detected = true;
if ((recv_probe || rs_->wasNacked(seq)) && !rs_->isFecOn()) {
// these losses were detected using a probe and fec is off.
// in this case most likelly the procotol is about to go out of sync
// and the packets are not really lost (e.g. increase in prod rate).
// for this reason we do not
// count the losses in the stats. Instead we do the following
// 1. send RTX for the packets in case they were really lost
// 2. return to the RTC protocol that a loss was detected using a
// probe. the protocol will switch to catch_up mode to increase the
// size of the window
rs_->requestPossibleLostPacket(seq);
} else {
// if fec is on we don't need to mask pontetial losses, so increase
// the loss rate
rs_->notifyNewLossDetedcted(seq);
}
}
}
}
return loss_detected;
}
} // namespace rtc
} // namespace protocol
} // namespace transport
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