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/*
* Copyright 2018 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "test/scenario/simulated_time.h"
#include <algorithm>
#include "rtc_base/format_macros.h"
namespace webrtc {
namespace test {
namespace {
struct RawFeedbackReportPacket {
static constexpr int MAX_FEEDBACKS = 10;
struct Feedback {
int16_t seq_offset;
int32_t recv_offset_ms;
};
uint8_t count;
int64_t first_seq_num;
int64_t first_recv_time_ms;
Feedback feedbacks[MAX_FEEDBACKS - 1];
};
} // namespace
PacketStream::PacketStream(PacketStreamConfig config) : config_(config) {}
std::vector<int64_t> PacketStream::PullPackets(Timestamp at_time) {
if (next_frame_time_.IsInfinite())
next_frame_time_ = at_time;
TimeDelta frame_interval = TimeDelta::seconds(1) / config_.frame_rate;
int64_t frame_allowance = (frame_interval * target_rate_).bytes();
if (next_frame_is_keyframe_) {
frame_allowance *= config_.keyframe_multiplier;
next_frame_is_keyframe_ = false;
}
std::vector<int64_t> packets;
while (at_time >= next_frame_time_) {
next_frame_time_ += frame_interval;
int64_t frame_size = budget_ + frame_allowance;
frame_size = std::max(frame_size, config_.min_frame_size.bytes());
budget_ += frame_allowance - frame_size;
int64_t packet_budget = frame_size;
int64_t max_packet_size = config_.max_packet_size.bytes();
while (packet_budget > max_packet_size) {
packets.push_back(max_packet_size);
packet_budget -= max_packet_size;
}
packets.push_back(packet_budget);
}
for (int64_t& packet : packets)
packet += config_.packet_overhead.bytes();
return packets;
}
void PacketStream::OnTargetRateUpdate(DataRate target_rate) {
target_rate_ = std::min(target_rate, config_.max_data_rate);
}
SimpleFeedbackReportPacket FeedbackFromBuffer(
rtc::CopyOnWriteBuffer raw_buffer) {
RTC_CHECK_LE(sizeof(RawFeedbackReportPacket), raw_buffer.size());
const RawFeedbackReportPacket& raw_packet =
*reinterpret_cast<const RawFeedbackReportPacket*>(raw_buffer.cdata());
RTC_CHECK_GE(raw_packet.count, 1);
SimpleFeedbackReportPacket packet;
packet.receive_times.emplace_back(SimpleFeedbackReportPacket::ReceiveInfo{
raw_packet.first_seq_num, Timestamp::ms(raw_packet.first_recv_time_ms)});
for (int i = 1; i < raw_packet.count; ++i)
packet.receive_times.emplace_back(SimpleFeedbackReportPacket::ReceiveInfo{
raw_packet.first_seq_num + raw_packet.feedbacks[i - 1].seq_offset,
Timestamp::ms(raw_packet.first_recv_time_ms +
raw_packet.feedbacks[i - 1].recv_offset_ms)});
return packet;
}
rtc::CopyOnWriteBuffer FeedbackToBuffer(
const SimpleFeedbackReportPacket packet) {
RTC_CHECK_LE(packet.receive_times.size(),
RawFeedbackReportPacket::MAX_FEEDBACKS);
RawFeedbackReportPacket report;
report.count = packet.receive_times.size();
RTC_CHECK(!packet.receive_times.empty());
report.first_seq_num = packet.receive_times.front().sequence_number;
report.first_recv_time_ms = packet.receive_times.front().receive_time.ms();
for (int i = 1; i < report.count; ++i) {
report.feedbacks[i - 1].seq_offset = static_cast<int16_t>(
packet.receive_times[i].sequence_number - report.first_seq_num);
report.feedbacks[i - 1].recv_offset_ms = static_cast<int32_t>(
packet.receive_times[i].receive_time.ms() - report.first_recv_time_ms);
}
return rtc::CopyOnWriteBuffer(reinterpret_cast<uint8_t*>(&report),
sizeof(RawFeedbackReportPacket));
}
SimulatedSender::SimulatedSender(NetworkNode* send_node,
uint64_t send_receiver_id)
: send_node_(send_node), send_receiver_id_(send_receiver_id) {}
SimulatedSender::~SimulatedSender() {}
TransportPacketsFeedback SimulatedSender::PullFeedbackReport(
SimpleFeedbackReportPacket packet,
Timestamp at_time) {
TransportPacketsFeedback report;
report.prior_in_flight = data_in_flight_;
report.feedback_time = at_time;
for (auto& receive_info : packet.receive_times) {
// Look up sender side information for all packets up to and including each
// packet with feedback in the report.
for (; next_feedback_seq_num_ <= receive_info.sequence_number;
++next_feedback_seq_num_) {
PacketResult feedback;
if (next_feedback_seq_num_ == receive_info.sequence_number) {
feedback.receive_time = receive_info.receive_time;
} else {
// If we did not get any feedback for this packet, mark it as lost by
// setting receive time to infinity. Note that this can also happen due
// to reordering, we will newer send feedback out of order. In this case
// the packet was not really lost, but we don't have that information.
feedback.receive_time = Timestamp::PlusInfinity();
}
// Looking up send side information.
for (auto it = sent_packets_.begin(); it != sent_packets_.end(); ++it) {
if (it->sequence_number == next_feedback_seq_num_) {
feedback.sent_packet = *it;
if (feedback.receive_time.IsFinite())
sent_packets_.erase(it);
break;
}
}
data_in_flight_ -= feedback.sent_packet.size;
report.packet_feedbacks.push_back(feedback);
}
}
report.data_in_flight = data_in_flight_;
return report;
}
// Applies pacing and congetsion window based on the configuration from the
// congestion controller. This is not a complete implementation of the real
// pacer but useful for unit tests since it isn't limited to real time.
std::vector<SimulatedSender::PacketReadyToSend>
SimulatedSender::PaceAndPullSendPackets(Timestamp at_time) {
// TODO(srte): Extract the behavior of PacedSender to a threading and time
// independent component and use that here to allow a truthful simulation.
if (last_update_.IsInfinite()) {
pacing_budget_ = 0;
} else {
TimeDelta delta = at_time - last_update_;
pacing_budget_ += (delta * pacer_config_.data_rate()).bytes();
}
std::vector<PacketReadyToSend> to_send;
while (data_in_flight_ <= max_in_flight_ && pacing_budget_ >= 0 &&
!packet_queue_.empty()) {
PendingPacket pending = packet_queue_.front();
pacing_budget_ -= pending.size;
packet_queue_.pop_front();
SentPacket sent;
sent.sequence_number = next_sequence_number_++;
sent.size = DataSize::bytes(pending.size);
data_in_flight_ += sent.size;
sent.data_in_flight = data_in_flight_;
sent.pacing_info = PacedPacketInfo();
sent.send_time = at_time;
sent_packets_.push_back(sent);
rtc::CopyOnWriteBuffer packet(
std::max<size_t>(pending.size, sizeof(sent.sequence_number)));
memcpy(packet.data(), &sent.sequence_number, sizeof(sent.sequence_number));
to_send.emplace_back(PacketReadyToSend{sent, packet});
}
pacing_budget_ = std::min<int64_t>(pacing_budget_, 0);
last_update_ = at_time;
return to_send;
}
void SimulatedSender::Update(NetworkControlUpdate update) {
if (update.pacer_config)
pacer_config_ = *update.pacer_config;
if (update.congestion_window)
max_in_flight_ = *update.congestion_window;
}
SimulatedFeedback::SimulatedFeedback(SimulatedTimeClientConfig config,
uint64_t return_receiver_id,
NetworkNode* return_node)
: config_(config),
return_receiver_id_(return_receiver_id),
return_node_(return_node) {}
// Polls receiver side for a feedback report and sends it to the stream sender
// via return_node_,
bool SimulatedFeedback::TryDeliverPacket(rtc::CopyOnWriteBuffer packet,
uint64_t receiver,
Timestamp at_time) {
int64_t sequence_number;
memcpy(&sequence_number, packet.cdata(), sizeof(sequence_number));
receive_times_.insert({sequence_number, at_time});
if (last_feedback_time_.IsInfinite())
last_feedback_time_ = at_time;
if (at_time >= last_feedback_time_ + config_.feedback.interval) {
SimpleFeedbackReportPacket report;
for (; next_feedback_seq_num_ <= sequence_number;
++next_feedback_seq_num_) {
auto it = receive_times_.find(next_feedback_seq_num_);
if (it != receive_times_.end()) {
report.receive_times.emplace_back(
SimpleFeedbackReportPacket::ReceiveInfo{next_feedback_seq_num_,
it->second});
receive_times_.erase(it);
}
if (receive_times_.size() >= RawFeedbackReportPacket::MAX_FEEDBACKS) {
return_node_->TryDeliverPacket(FeedbackToBuffer(report),
return_receiver_id_, at_time);
report = SimpleFeedbackReportPacket();
}
}
if (!report.receive_times.empty())
return_node_->TryDeliverPacket(FeedbackToBuffer(report),
return_receiver_id_, at_time);
last_feedback_time_ = at_time;
}
return true;
}
SimulatedTimeClient::SimulatedTimeClient(
std::string log_filename,
SimulatedTimeClientConfig config,
std::vector<PacketStreamConfig> stream_configs,
std::vector<NetworkNode*> send_link,
std::vector<NetworkNode*> return_link,
uint64_t send_receiver_id,
uint64_t return_receiver_id,
Timestamp at_time)
: network_controller_factory_(log_filename, config.transport),
send_link_(send_link),
return_link_(return_link),
sender_(send_link.front(), send_receiver_id),
feedback_(config, return_receiver_id, return_link.front()) {
current_contraints_.at_time = at_time;
current_contraints_.starting_rate = config.transport.rates.start_rate;
current_contraints_.min_data_rate = config.transport.rates.min_rate;
current_contraints_.max_data_rate = config.transport.rates.max_rate;
NetworkControllerConfig initial_config;
initial_config.constraints = current_contraints_;
congestion_controller_ = network_controller_factory_.Create(initial_config);
for (auto& stream_config : stream_configs)
packet_streams_.emplace_back(new PacketStream(stream_config));
NetworkNode::Route(send_receiver_id, send_link, &feedback_);
NetworkNode::Route(return_receiver_id, return_link, this);
CongestionProcess(at_time);
network_controller_factory_.LogCongestionControllerStats(at_time);
if (!log_filename.empty()) {
std::string packet_log_name = log_filename + ".packets.txt";
packet_log_ = fopen(packet_log_name.c_str(), "w");
fprintf(packet_log_,
"transport_seq packet_size send_time recv_time feed_time\n");
}
}
// Pulls feedback reports from sender side based on the recieved feedback
// packet. Updates congestion controller with the resulting report.
bool SimulatedTimeClient::TryDeliverPacket(rtc::CopyOnWriteBuffer raw_buffer,
uint64_t receiver,
Timestamp at_time) {
auto report =
sender_.PullFeedbackReport(FeedbackFromBuffer(raw_buffer), at_time);
for (PacketResult& feedback : report.packet_feedbacks) {
if (packet_log_)
fprintf(packet_log_, "%" PRId64 " %" PRId64 " %.3lf %.3lf %.3lf\n",
feedback.sent_packet.sequence_number,
feedback.sent_packet.size.bytes(),
feedback.sent_packet.send_time.seconds<double>(),
feedback.receive_time.seconds<double>(),
at_time.seconds<double>());
}
Update(congestion_controller_->OnTransportPacketsFeedback(report));
return true;
}
SimulatedTimeClient::~SimulatedTimeClient() {
if (packet_log_)
fclose(packet_log_);
}
void SimulatedTimeClient::Update(NetworkControlUpdate update) {
sender_.Update(update);
if (update.target_rate) {
// TODO(srte): Implement more realistic distribution of bandwidths between
// streams. Either using BitrateAllocationStrategy directly or using
// BitrateAllocation.
double ratio_per_stream = 1.0 / packet_streams_.size();
DataRate rate_per_stream =
update.target_rate->target_rate * ratio_per_stream;
target_rate_ = update.target_rate->target_rate;
for (auto& stream : packet_streams_)
stream->OnTargetRateUpdate(rate_per_stream);
}
}
void SimulatedTimeClient::CongestionProcess(Timestamp at_time) {
ProcessInterval msg;
msg.at_time = at_time;
Update(congestion_controller_->OnProcessInterval(msg));
}
void SimulatedTimeClient::PacerProcess(Timestamp at_time) {
ProcessFrames(at_time);
for (auto to_send : sender_.PaceAndPullSendPackets(at_time)) {
sender_.send_node_->TryDeliverPacket(to_send.data,
sender_.send_receiver_id_, at_time);
Update(congestion_controller_->OnSentPacket(to_send.send_info));
}
}
void SimulatedTimeClient::ProcessFrames(Timestamp at_time) {
for (auto& stream : packet_streams_) {
for (int64_t packet_size : stream->PullPackets(at_time)) {
sender_.packet_queue_.push_back(
SimulatedSender::PendingPacket{packet_size});
}
}
}
void SimulatedTimeClient::TriggerFakeReroute(Timestamp at_time) {
NetworkRouteChange msg;
msg.at_time = at_time;
msg.constraints = current_contraints_;
msg.constraints.at_time = at_time;
Update(congestion_controller_->OnNetworkRouteChange(msg));
}
TimeDelta SimulatedTimeClient::GetNetworkControllerProcessInterval() const {
return network_controller_factory_.GetProcessInterval();
}
double SimulatedTimeClient::target_rate_kbps() const {
return target_rate_.kbps<double>();
}
} // namespace test
} // namespace webrtc