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// Copyright (C) 2012-2021 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#include <config.h>
#include <perfdhcp/avalanche_scen.h>
#include <boost/date_time/posix_time/posix_time.hpp>
using namespace std;
using namespace boost::posix_time;
using namespace isc;
using namespace isc::dhcp;
namespace isc {
namespace perfdhcp {
int
AvalancheScen::resendPackets(ExchangeType xchg_type) {
const StatsMgr& stats_mgr(tc_.getStatsMgr());
// get list of sent packets that potentially need to be resent
auto sent_packets_its = stats_mgr.getSentPackets(xchg_type);
auto begin_it = std::get<0>(sent_packets_its);
auto end_it = std::get<1>(sent_packets_its);
auto& retrans = retransmissions_[xchg_type];
auto& start_times = start_times_[xchg_type];
int still_left_cnt = 0;
int current_cycle_resent_cnt = 0;
for (auto it = begin_it; it != end_it; ++it) {
still_left_cnt++;
dhcp::PktPtr pkt = *it;
auto trans_id = pkt->getTransid();
// get some things from previous retransmissions
auto start_time = pkt->getTimestamp();
int current_pkt_resent_cnt = 0;
auto r_it = retrans.find(trans_id);
if (r_it != retrans.end()) {
start_time = (*start_times.find(trans_id)).second;
current_pkt_resent_cnt = (*r_it).second;
} else {
start_times[trans_id] = start_time;
}
// estimate back off time for resending this packet
int delay = (1 << current_pkt_resent_cnt); // in seconds
if (delay > 64) {
delay = 64;
}
delay *= 1000; // to miliseconds
delay += random() % 2000 - 1000; // adjust by random from -1000..1000 range
// if back-off time passed then resend
auto now = microsec_clock::universal_time();
if (now - start_time > milliseconds(delay)) {
current_cycle_resent_cnt++;
total_resent_++;
// do resend packet
if (options_.getIpVersion() == 4) {
Pkt4Ptr pkt4 = boost::dynamic_pointer_cast<Pkt4>(pkt);
socket_.send(pkt4);
} else {
Pkt6Ptr pkt6 = boost::dynamic_pointer_cast<Pkt6>(pkt);
socket_.send(pkt6);
}
// restore sending time of original packet
pkt->setTimestamp(start_time);
current_pkt_resent_cnt++;
retrans[trans_id] = current_pkt_resent_cnt;
}
}
if (current_cycle_resent_cnt > 0) {
auto now = microsec_clock::universal_time();
std::cout << now << " " << xchg_type << ": still waiting for "
<< still_left_cnt << " answers, resent " << current_cycle_resent_cnt
<< ", retrying " << retrans.size() << std::endl;
}
return still_left_cnt;
}
int
AvalancheScen::run() {
// First indicated number of DISCOVER packets eg. 4000 are sent.
// Then in a loop responses to received packets (this is
// consumeReceivedPackets()) are sent and then for every 200ms it is checked
// if responses to sent packets were received. If not packets are resent.
// This happens in resendPackets() method. For each packet it is checked
// how many times it was already resent and then back off time is calculated:
// 1, 2, 4, 8, 16, 64 (max) seconds. If estimated time has elapsed
// from previous sending then the packet is resent. Some stats are collected
// and printed during runtime. The whole procedure is stopped when
// all packets got responses.
uint32_t clients_num = options_.getClientsNum() == 0 ?
1 : options_.getClientsNum();
StatsMgr& stats_mgr(tc_.getStatsMgr());
tc_.start();
auto start = microsec_clock::universal_time();
// Initiate new DHCP packet exchanges.
tc_.sendPackets(clients_num);
auto now = microsec_clock::universal_time();
auto prev_cycle_time = now;
for (;;) {
// Pull some packets from receiver thread, process them, update some stats
// and respond to the server if needed.
tc_.consumeReceivedPackets();
usleep(100);
now = microsec_clock::universal_time();
// Wait for 200ms between subsequent check for resending.
// This time taken based on experiments. For times 10-30ms whole scenario
// time significantly grows. The same for times >200ms. The optimal times
// are between 50-200ms. \todo more research is needed.
if (now - prev_cycle_time > milliseconds(200)) { // check if 0.2s elapsed
prev_cycle_time = now;
int still_left_cnt = 0;
still_left_cnt += resendPackets(stage1_xchg_);
if (options_.getExchangeMode() == CommandOptions::DORA_SARR) {
still_left_cnt += resendPackets(stage2_xchg_);
}
if (still_left_cnt == 0) {
break;
}
}
if (tc_.interrupted()) {
break;
}
}
auto stop = microsec_clock::universal_time();
boost::posix_time::time_period duration(start, stop);
tc_.stop();
tc_.printStats();
// Print packet timestamps
if (options_.testDiags('t')) {
stats_mgr.printTimestamps();
}
// Print server id.
if (options_.testDiags('s') && tc_.serverIdReceived()) {
std::cout << "Server id: " << tc_.getServerId() << std::endl;
}
// Diagnostics flag 'e' means show exit reason.
if (options_.testDiags('e')) {
std::cout << "Interrupted" << std::endl;
}
// Print any received leases.
if (options_.testDiags('l')) {
stats_mgr.printLeases();
}
// Calculate total stats.
int total_sent_pkts = total_resent_; // This holds sent + resent packets counts.
int total_rcvd_pkts = 0; // This holds received packets count.
// Get sent and received counts for DO/SA (stage1) exchange from StatsMgr.
total_sent_pkts += tc_.getStatsMgr().getSentPacketsNum(stage1_xchg_);
total_rcvd_pkts += tc_.getStatsMgr().getRcvdPacketsNum(stage1_xchg_);
// Get sent and received counts for RA/RR (stage2) exchange from StatsMgr
// if RA/RR was not disabled.
if (options_.getExchangeMode() == CommandOptions::DORA_SARR) {
total_sent_pkts += tc_.getStatsMgr().getSentPacketsNum(stage2_xchg_);
total_rcvd_pkts += tc_.getStatsMgr().getRcvdPacketsNum(stage2_xchg_);
}
std::cout << "It took " << duration.length() << " to provision " << clients_num
<< " clients. " << std::endl
<< "Requests sent + resent: " << total_sent_pkts << std::endl
<< "Requests resent: " << total_resent_ << std::endl
<< "Responses received: " << total_rcvd_pkts << std::endl;
return (0);
}
} // namespace perfdhcp
} // namespace isc
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