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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_rs_low_rate.h>
namespace transport {
namespace protocol {
namespace rtc {
RecoveryStrategyLowRate::RecoveryStrategyLowRate(
Indexer *indexer, SendRtxCallback &&callback, asio::io_service &io_service,
interface::RtcTransportRecoveryStrategies rs_type,
interface::StrategyCallback &&external_callback)
: RecoveryStrategy(indexer, std::move(callback), io_service, false, true,
rs_type,
std::move(external_callback)), // start with fec
fec_consecutive_rounds_((MILLI_IN_A_SEC / ROUND_LEN) * 5), // 5 sec
rtx_allowed_consecutive_rounds_(0) {
initSwitchVector();
}
RecoveryStrategyLowRate::RecoveryStrategyLowRate(RecoveryStrategy &&rs)
: RecoveryStrategy(std::move(rs)),
fec_consecutive_rounds_((MILLI_IN_A_SEC / ROUND_LEN) * 5), // 5 sec
rtx_allowed_consecutive_rounds_(0) {
setRtxFec(false, true);
initSwitchVector();
}
RecoveryStrategyLowRate::~RecoveryStrategyLowRate() {}
void RecoveryStrategyLowRate::initSwitchVector() {
// TODO adjust thresholds here when new data are collected
// see resutls in
// https://confluence-eng-gpk1.cisco.com/conf/display/SPT/dailyreports
thresholds_t t1;
t1.rtt = 15; // 15ms
t1.loss_rtx_to_fec = 15; // 15%
t1.loss_fec_to_rtx = 10; // 10%
thresholds_t t2;
t2.rtt = 35; // 35ms
t2.loss_rtx_to_fec = 5; // 5%
t2.loss_fec_to_rtx = 1; // 1%
switch_vector.push_back(t1);
switch_vector.push_back(t2);
}
void RecoveryStrategyLowRate::setRecoveryParameters(bool use_rtx, bool use_fec,
uint32_t fec_to_ask) {
setRtxFec(use_rtx, use_fec);
indexer_->setNFec(fec_to_ask);
}
void RecoveryStrategyLowRate::selectRecoveryStrategy(bool in_sync) {
uint32_t fec_to_ask = computeFecPacketsToAsk();
if (fec_to_ask == 0) {
// fec is off, turn on RTX immediatly to avoid packet losses
setRecoveryParameters(true, false, 0);
fec_consecutive_rounds_ = 0;
return;
}
uint32_t loss_rate = std::round(state_->getPerSecondLossRate() * 100);
uint32_t rtt = (uint32_t)state_->getAvgRTT();
bool use_rtx = false;
for (size_t i = 0; i < switch_vector.size(); i++) {
uint32_t max_loss_rate = 0;
if (fec_on_)
max_loss_rate = switch_vector[i].loss_fec_to_rtx;
else
max_loss_rate = switch_vector[i].loss_rtx_to_fec;
if (rtt < switch_vector[i].rtt && loss_rate < max_loss_rate) {
use_rtx = true;
rtx_allowed_consecutive_rounds_++;
break;
}
}
if (!use_rtx) rtx_allowed_consecutive_rounds_ = 0;
if (use_rtx) {
if (fec_on_) {
// here we should swtich from RTX to FEC
// wait 10sec where the switch is allowed before actually switch
if (rtx_allowed_consecutive_rounds_ >=
((MILLI_IN_A_SEC / ROUND_LEN) * 10)) { // 10 sec
// use RTX
setRecoveryParameters(true, false, 0);
fec_consecutive_rounds_ = 0;
} else {
// keep using FEC (and maybe RTX)
setRecoveryParameters(true, true, fec_to_ask);
fec_consecutive_rounds_++;
}
} else {
// keep using RTX
setRecoveryParameters(true, false, 0);
fec_consecutive_rounds_ = 0;
}
} else {
// use FEC and RTX
setRecoveryParameters(true, true, fec_to_ask);
fec_consecutive_rounds_++;
}
// everytime that we anable FEC we keep also RTX on. in this way the first
// losses that are not covered by FEC are recovered using RTX. after 5 sec we
// disable fec
if (fec_consecutive_rounds_ >= ((MILLI_IN_A_SEC / ROUND_LEN) * 5)) {
// turn off RTX
setRtxFec(false);
}
}
void RecoveryStrategyLowRate::turnOnRecovery() {
recovery_on_ = 1;
// the stategy will be init in the new round function
}
void RecoveryStrategyLowRate::onNewRound(bool in_sync) {
if (!recovery_on_) {
// disable fec so that no extra packet will be sent
// for rtx we check if recovery is on in newPacketLoss
setRtxFec(true, false);
indexer_->setNFec(0);
return;
}
// XXX since this strategy will be used only for flow at low rate we do not
// consider congestion events like in other strategies
selectRecoveryStrategy(in_sync);
}
void RecoveryStrategyLowRate::newPacketLoss(uint32_t seq) {
if (rtx_on_ && recovery_on_) {
addNewRtx(seq, false);
} else {
if (!state_->isPending(seq) && !indexer_->isFec(seq)) {
addNewRtx(seq, true);
} else {
recover_with_fec_.insert(seq);
state_->onPossibleLossWithNoRtx(seq);
}
}
}
void RecoveryStrategyLowRate::receivedPacket(uint32_t seq) {
removePacketState(seq);
}
} // end namespace rtc
} // end namespace protocol
} // end namespace transport
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