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/*
* Copyright (c) 2017-2019 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 <protocols/rtc/rtc_data_path.h>
#include <stdlib.h>
#include <algorithm>
#include <cfloat>
#include <chrono>
#define MAX_ROUNDS_WITHOUT_PKTS 10 // 2sec
namespace transport {
namespace protocol {
namespace rtc {
RTCDataPath::RTCDataPath(uint32_t path_id)
: path_id_(path_id),
min_rtt(UINT_MAX),
prev_min_rtt(UINT_MAX),
min_owd(INT_MAX), // this is computed like in LEDBAT, so it is not the
// real OWD, but the measured one, that depends on the
// clock of sender and receiver. the only meaningful
// value is is the queueing delay. for this reason we
// keep both RTT (for the windowd calculation) and OWD
// (for congestion/quality control)
prev_min_owd(INT_MAX),
avg_owd(DBL_MAX),
queuing_delay(DBL_MAX),
jitter_(0.0),
last_owd_(0),
largest_recv_seq_(0),
largest_recv_seq_time_(0),
avg_inter_arrival_(DBL_MAX),
received_nacks_(false),
received_packets_(false),
rounds_without_packets_(0),
last_received_data_packet_(0),
RTT_history_(HISTORY_LEN),
OWD_history_(HISTORY_LEN){};
void RTCDataPath::insertRttSample(uint64_t rtt) {
// for the rtt we only keep track of the min one
if (rtt < min_rtt) min_rtt = rtt;
last_received_data_packet_ =
std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::steady_clock::now().time_since_epoch())
.count();
}
void RTCDataPath::insertOwdSample(int64_t owd) {
// for owd we use both min and avg
if (owd < min_owd) min_owd = owd;
if (avg_owd != DBL_MAX)
avg_owd = (avg_owd * (1 - ALPHA_RTC)) + (owd * ALPHA_RTC);
else {
avg_owd = (double)owd;
}
int64_t queueVal = owd - std::min(getMinOwd(), min_owd);
if (queuing_delay != DBL_MAX)
queuing_delay = (queuing_delay * (1 - ALPHA_RTC)) + (queueVal * ALPHA_RTC);
else {
queuing_delay = (double)queueVal;
}
// keep track of the jitter computed as for RTP (RFC 3550)
int64_t diff = std::abs(owd - last_owd_);
last_owd_ = owd;
jitter_ += (1.0 / 16.0) * ((double)diff - jitter_);
// owd is computed only for valid data packets so we count only
// this for decide if we recevie traffic or not
received_packets_ = true;
}
void RTCDataPath::computeInterArrivalGap(uint32_t segment_number) {
// got packet in sequence, compute gap
if (largest_recv_seq_ == (segment_number - 1)) {
uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::steady_clock::now().time_since_epoch())
.count();
uint64_t delta = now - largest_recv_seq_time_;
largest_recv_seq_ = segment_number;
largest_recv_seq_time_ = now;
if (avg_inter_arrival_ == DBL_MAX)
avg_inter_arrival_ = (double)delta;
else
avg_inter_arrival_ =
(avg_inter_arrival_ * (1 - ALPHA_RTC)) + (delta * ALPHA_RTC);
return;
}
// ooo packet, update the stasts if needed
if (largest_recv_seq_ <= segment_number) {
largest_recv_seq_ = segment_number;
largest_recv_seq_time_ =
std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::steady_clock::now().time_since_epoch())
.count();
}
}
void RTCDataPath::receivedNack() { received_nacks_ = true; }
double RTCDataPath::getInterArrivalGap() {
if (avg_inter_arrival_ == DBL_MAX) return 0;
return avg_inter_arrival_;
}
bool RTCDataPath::isActive() {
if (received_nacks_ && rounds_without_packets_ < MAX_ROUNDS_WITHOUT_PKTS)
return true;
return false;
}
bool RTCDataPath::pathToProducer() {
if (received_nacks_) return true;
return false;
}
void RTCDataPath::roundEnd() {
// reset min_rtt and add it to the history
if (min_rtt != UINT_MAX) {
prev_min_rtt = min_rtt;
} else {
// this may happen if we do not receive any packet
// from this path in the last round. in this case
// we use the measure from the previuos round
min_rtt = prev_min_rtt;
}
if (min_rtt == 0) min_rtt = 1;
RTT_history_.pushBack(min_rtt);
min_rtt = UINT_MAX;
// do the same for min owd
if (min_owd != INT_MAX) {
prev_min_owd = min_owd;
} else {
min_owd = prev_min_owd;
}
if (min_owd != INT_MAX) {
OWD_history_.pushBack(min_owd);
min_owd = INT_MAX;
}
if (!received_packets_)
rounds_without_packets_++;
else
rounds_without_packets_ = 0;
received_packets_ = false;
}
uint32_t RTCDataPath::getPathId() { return path_id_; }
double RTCDataPath::getQueuingDealy() { return queuing_delay; }
uint64_t RTCDataPath::getMinRtt() {
if (RTT_history_.size() != 0) return RTT_history_.begin();
return 0;
}
int64_t RTCDataPath::getMinOwd() {
if (OWD_history_.size() != 0) return OWD_history_.begin();
return 0;
}
double RTCDataPath::getJitter() { return jitter_; }
uint64_t RTCDataPath::getLastPacketTS() { return last_received_data_packet_; }
void RTCDataPath::clearRtt() { RTT_history_.clear(); }
} // end namespace rtc
} // end namespace protocol
} // end namespace transport
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