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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.
*/
#pragma once
#include <hicn/transport/interfaces/callbacks.h>
#include <hicn/transport/utils/chrono_typedefs.h>
#include <protocols/indexer.h>
#include <protocols/rtc/rtc_rc.h>
#include <protocols/rtc/rtc_state.h>
#include <map>
#include <unordered_map>
namespace transport {
namespace protocol {
namespace rtc {
class RecoveryStrategy : public std::enable_shared_from_this<RecoveryStrategy> {
protected:
struct rtx_state_ {
uint64_t first_send_;
uint64_t next_send_;
uint32_t rtx_count_;
};
using rtxState = struct rtx_state_;
public:
using SendRtxCallback = std::function<void(uint32_t)>;
RecoveryStrategy(Indexer *indexer, SendRtxCallback &&callback,
asio::io_service &io_service, bool use_rtx, bool use_fec,
interface::StrategyCallback &&external_callback);
RecoveryStrategy(RecoveryStrategy &&rs);
virtual ~RecoveryStrategy();
void setRtxFec(std::optional<bool> rtx_on = {},
std::optional<bool> fec_on = {});
void setState(RTCState *state) { state_ = state; }
void setRateControl(RTCRateControl *rateControl) { rc_ = rateControl; }
void setFecParams(uint32_t n, uint32_t k);
bool isRtx(uint32_t seq) {
if (rtx_state_.find(seq) != rtx_state_.end()) return true;
return false;
}
bool isPossibleLossWithNoRtx(uint32_t seq) {
if (recover_with_fec_.find(seq) != recover_with_fec_.end()) return true;
return false;
}
bool wasNacked(uint32_t seq) {
if (nacked_seq_.find(seq) != nacked_seq_.end()) return true;
return false;
}
bool isRtxOn() { return rtx_on_; }
bool isFecOn() { return fec_on_; }
RTCState *getState() { return state_; }
bool lossDetected(uint32_t seq);
void notifyNewLossDetedcted(uint32_t seq);
void requestPossibleLostPacket(uint32_t seq);
void receivedFutureNack(uint32_t seq);
void clear();
virtual void turnOnRecovery() = 0;
virtual void onNewRound(bool in_sync) = 0;
virtual void newPacketLoss(uint32_t seq) = 0;
virtual void receivedPacket(uint32_t seq) = 0;
void onLostTimeout(uint32_t seq);
void incRoundId() { round_id_++; }
// utils
uint64_t getNow() {
uint64_t now = utils::SteadyTime::nowMs().count();
return now;
}
protected:
// rtx functions
void addNewRtx(uint32_t seq, bool force);
uint64_t computeNextSend(uint32_t seq, bool new_rtx);
void retransmit();
void scheduleNextRtx();
void deleteRtx(uint32_t seq);
// fec functions
uint32_t computeFecPacketsToAsk();
// common functons
void removePacketState(uint32_t seq);
bool recovery_on_;
bool rtx_on_;
bool fec_on_;
// number of RTX sent after fec turned on
// this is used to take into account jitter and out of order packets
// if we detect losses but we do not sent any RTX it means that the holes in
// the sequence are caused by the jitter
uint32_t rtx_during_fec_;
// this map keeps track of the retransmitted interest, ordered from the oldest
// to the newest one. the state contains the timer of the first send of the
// interest (from pendingIntetests_), the timer of the next send (key of the
// multimap) and the number of rtx
std::map<uint32_t, rtxState> rtx_state_;
// this map stored the rtx by timer. The key is the time at which the rtx
// should be sent, and the val is the interest seq number
std::multimap<uint64_t, uint32_t> rtx_timers_;
// lost packets that will be recovered with fec
std::unordered_set<uint32_t> recover_with_fec_;
// packet for which we recived a future nack
// in case we detect a loss for a nacked packet we send an RTX but we do not
// increase the loss counter. this is done because it may happen that the
// producer rate checkes over time and in flight interest may be satified by
// data packet after the reception of nacks
std::unordered_set<uint32_t> nacked_seq_;
// rtx vars
std::unique_ptr<asio::steady_timer> timer_;
uint64_t next_rtx_timer_;
SendRtxCallback send_rtx_callback_;
// fec vars
uint32_t n_;
uint32_t k_;
Indexer *indexer_;
RTCState *state_;
RTCRateControl *rc_;
private:
struct fec_state_ {
uint32_t fec_to_ask;
uint32_t last_update; // round id of the last update
// (wait 10 ruonds (2sec) between updates)
uint32_t consecutive_use; // consecutive ruonds where this fec was used
double avg_residual_losses;
};
void reduceFec();
uint32_t round_id_; // number of rounds
uint32_t last_fec_used_;
std::vector<fec_state_> fec_per_loss_rate_;
interface::StrategyCallback callback_;
};
} // end namespace rtc
} // end namespace protocol
} // end namespace transport
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