Implement a very basic MoQT simulator.
This should help us tune MoQT performance by having a simulated lab setup that lets us iterate easily.
This CL also fixes a bunch of code that spams irrelevant messages into logs when running the simulator.
PiperOrigin-RevId: 642365065
diff --git a/build/source_list.bzl b/build/source_list.bzl
index e4bfad3..bbe3b4c 100644
--- a/build/source_list.bzl
+++ b/build/source_list.bzl
@@ -1534,6 +1534,7 @@
"quic/moqt/tools/moqt_end_to_end_test.cc",
"quic/moqt/tools/moqt_ingestion_server_bin.cc",
"quic/moqt/tools/moqt_server.cc",
+ "quic/moqt/tools/moqt_simulator_bin.cc",
]
binary_http_hdrs = [
"binary_http/binary_http_message.h",
diff --git a/build/source_list.gni b/build/source_list.gni
index 60c5103..3429497 100644
--- a/build/source_list.gni
+++ b/build/source_list.gni
@@ -1538,6 +1538,7 @@
"src/quiche/quic/moqt/tools/moqt_end_to_end_test.cc",
"src/quiche/quic/moqt/tools/moqt_ingestion_server_bin.cc",
"src/quiche/quic/moqt/tools/moqt_server.cc",
+ "src/quiche/quic/moqt/tools/moqt_simulator_bin.cc",
]
binary_http_hdrs = [
"src/quiche/binary_http/binary_http_message.h",
diff --git a/build/source_list.json b/build/source_list.json
index b34b8f9..12fec03 100644
--- a/build/source_list.json
+++ b/build/source_list.json
@@ -1536,7 +1536,8 @@
"quiche/quic/moqt/tools/moqt_client.cc",
"quiche/quic/moqt/tools/moqt_end_to_end_test.cc",
"quiche/quic/moqt/tools/moqt_ingestion_server_bin.cc",
- "quiche/quic/moqt/tools/moqt_server.cc"
+ "quiche/quic/moqt/tools/moqt_server.cc",
+ "quiche/quic/moqt/tools/moqt_simulator_bin.cc"
],
"binary_http_hdrs": [
"quiche/binary_http/binary_http_message.h"
diff --git a/quiche/quic/moqt/moqt_messages.h b/quiche/quic/moqt/moqt_messages.h
index da72fea..8d68733 100644
--- a/quiche/quic/moqt/moqt_messages.h
+++ b/quiche/quic/moqt/moqt_messages.h
@@ -14,6 +14,7 @@
#include <utility>
#include <vector>
+#include "absl/strings/str_format.h"
#include "absl/strings/string_view.h"
#include "quiche/quic/core/quic_time.h"
#include "quiche/quic/core/quic_types.h"
@@ -157,6 +158,11 @@
}
template <typename H>
friend H AbslHashValue(H h, const FullSequence& m);
+
+ template <typename Sink>
+ friend void AbslStringify(Sink& sink, const FullSequence& sequence) {
+ absl::Format(&sink, "(%d; %d)", sequence.group, sequence.object);
+ }
};
template <typename H>
diff --git a/quiche/quic/moqt/moqt_session.cc b/quiche/quic/moqt/moqt_session.cc
index 06d2808..bb86c12 100644
--- a/quiche/quic/moqt/moqt_session.cc
+++ b/quiche/quic/moqt/moqt_session.cc
@@ -482,11 +482,11 @@
++failures;
continue;
}
- QUICHE_LOG(INFO) << ENDPOINT << "Sending object length " << payload.length()
- << " for " << full_track_name.track_namespace << ":"
- << full_track_name.track_name << " with sequence "
- << object.group_id << ":" << object.object_id
- << " on stream " << *stream_id;
+ QUICHE_DVLOG(1) << ENDPOINT << "Sending object length " << payload.length()
+ << " for " << full_track_name.track_namespace << ":"
+ << full_track_name.track_name << " with sequence "
+ << object.group_id << ":" << object.object_id
+ << " on stream " << *stream_id;
if (end_of_stream && !new_stream) {
subscription->RemoveStream(group_id, object_id);
}
@@ -567,7 +567,7 @@
"Received OBJECT message on control stream");
return;
}
- QUICHE_DLOG(INFO)
+ QUICHE_DVLOG(1)
<< ENDPOINT << "Received OBJECT message on stream "
<< stream_->GetStreamId() << " for subscribe_id " << message.subscribe_id
<< " for track alias " << message.track_alias << " with sequence "
diff --git a/quiche/quic/moqt/tools/moqt_simulator_bin.cc b/quiche/quic/moqt/tools/moqt_simulator_bin.cc
new file mode 100644
index 0000000..bf11d97
--- /dev/null
+++ b/quiche/quic/moqt/tools/moqt_simulator_bin.cc
@@ -0,0 +1,325 @@
+// Copyright 2024 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// moqt_simulator simulates the behavior of MoQ Transport under various network
+// conditions and application settings.
+
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <iostream>
+#include <optional>
+#include <string>
+#include <utility>
+
+#include "absl/algorithm/container.h"
+#include "absl/container/flat_hash_map.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+#include "quiche/quic/core/crypto/quic_random.h"
+#include "quiche/quic/core/quic_bandwidth.h"
+#include "quiche/quic/core/quic_clock.h"
+#include "quiche/quic/core/quic_time.h"
+#include "quiche/quic/core/quic_types.h"
+#include "quiche/quic/moqt/moqt_messages.h"
+#include "quiche/quic/moqt/moqt_outgoing_queue.h"
+#include "quiche/quic/moqt/moqt_session.h"
+#include "quiche/quic/moqt/moqt_track.h"
+#include "quiche/quic/moqt/test_tools/moqt_simulator_harness.h"
+#include "quiche/quic/test_tools/simulator/actor.h"
+#include "quiche/quic/test_tools/simulator/link.h"
+#include "quiche/quic/test_tools/simulator/simulator.h"
+#include "quiche/quic/test_tools/simulator/switch.h"
+#include "quiche/common/platform/api/quiche_command_line_flags.h"
+#include "quiche/common/platform/api/quiche_logging.h"
+#include "quiche/common/platform/api/quiche_mem_slice.h"
+#include "quiche/common/quiche_buffer_allocator.h"
+#include "quiche/common/quiche_data_reader.h"
+#include "quiche/common/quiche_data_writer.h"
+#include "quiche/common/simple_buffer_allocator.h"
+
+namespace moqt::test {
+namespace {
+
+using ::quiche::QuicheBuffer;
+using ::quiche::QuicheMemSlice;
+
+using ::quic::QuicBandwidth;
+using ::quic::QuicByteCount;
+using ::quic::QuicClock;
+using ::quic::QuicTime;
+using ::quic::QuicTimeDelta;
+
+using ::quic::simulator::Simulator;
+
+// In the simulation, the server link is supposed to be the bottleneck, so this
+// value just has to be sufficiently larger than the server link bandwidth.
+constexpr QuicBandwidth kClientLinkBandwidth =
+ QuicBandwidth::FromBitsPerSecond(10.0e6);
+constexpr MoqtVersion kMoqtVersion = MoqtVersion::kDraft04;
+
+// Track name used by the simulator.
+FullTrackName TrackName() { return FullTrackName("test", "track"); }
+
+// Parameters describing the scenario being simulated.
+struct SimulationParameters {
+ // Bottleneck bandwidth of the simulated scenario.
+ QuicBandwidth bandwidth = QuicBandwidth::FromBitsPerSecond(2.0e6);
+ // Intended RTT (as computed from propagation delay alone) between the client
+ // and the server.
+ QuicTimeDelta min_rtt = QuicTimeDelta::FromMilliseconds(20);
+ // The size of the network queue; if zero, assumed to be twice the BDP.
+ QuicByteCount network_queue_size = 0;
+ // Duration for which the simulation is run.
+ QuicTimeDelta duration = QuicTimeDelta::FromSeconds(60);
+
+ // Number of frames in an individual group.
+ int keyframe_interval = 30 * 2;
+ // Number of frames generated per second.
+ int fps = 30;
+ // The ratio by which an I-frame is bigger than a P-frame.
+ float i_to_p_ratio = 2 / 1;
+ // The target bitrate of the data being exchanged.
+ QuicBandwidth bitrate = QuicBandwidth::FromBitsPerSecond(1.0e6);
+};
+
+// Generates test objects at a constant rate. The first eight bytes of every
+// object generated is a timestamp, the rest is all zeroes. The first object in
+// the group can be made bigger than the rest, to simulate the profile of real
+// video bitstreams.
+class ObjectGenerator : public quic::simulator::Actor {
+ public:
+ ObjectGenerator(Simulator* simulator, const std::string& actor_name,
+ MoqtSession* session, FullTrackName track_name,
+ int keyframe_interval, int fps, float i_to_p_ratio,
+ QuicBandwidth bitrate)
+ : Actor(simulator, actor_name),
+ queue_(session, track_name),
+ keyframe_interval_(keyframe_interval),
+ time_between_frames_(QuicTimeDelta::FromMicroseconds(1.0e6 / fps)) {
+ int p_frame_count = keyframe_interval - 1;
+ // Compute the frame sizes as a fraction of the total group size.
+ float i_frame_fraction = i_to_p_ratio / (i_to_p_ratio + p_frame_count);
+ float p_frame_fraction = 1.0 / (i_to_p_ratio + p_frame_count);
+
+ QuicTimeDelta group_duration =
+ QuicTimeDelta::FromMicroseconds(1.0e6 * keyframe_interval / fps);
+ QuicByteCount group_byte_count = group_duration * bitrate;
+ i_frame_size_ = i_frame_fraction * group_byte_count;
+ p_frame_size_ = p_frame_fraction * group_byte_count;
+ QUICHE_CHECK_GE(i_frame_size_, 8u) << "Not enough space for a timestamp";
+ QUICHE_CHECK_GE(p_frame_size_, 8u) << "Not enough space for a timestamp";
+ }
+
+ void Act() override {
+ ++frame_number_;
+ bool i_frame = (frame_number_ % keyframe_interval_) == 0;
+ size_t size = i_frame ? i_frame_size_ : p_frame_size_;
+
+ QuicheBuffer buffer(quiche::SimpleBufferAllocator::Get(), size);
+ memset(buffer.data(), 0, buffer.size());
+ quiche::QuicheDataWriter writer(size, buffer.data());
+ bool success = writer.WriteUInt64(clock_->Now().ToDebuggingValue());
+ QUICHE_CHECK(success);
+
+ queue_.AddObject(QuicheMemSlice(std::move(buffer)), i_frame);
+ Schedule(clock_->Now() + time_between_frames_);
+ }
+
+ void Start() { Schedule(clock_->Now()); }
+ void Stop() { Unschedule(); }
+
+ MoqtOutgoingQueue& queue() { return queue_; }
+ size_t total_objects_sent() const { return frame_number_ + 1; }
+
+ private:
+ MoqtOutgoingQueue queue_;
+ int keyframe_interval_;
+ QuicTimeDelta time_between_frames_;
+ QuicByteCount i_frame_size_;
+ QuicByteCount p_frame_size_;
+ int frame_number_ = -1;
+};
+
+class ObjectReceiver : public RemoteTrack::Visitor {
+ public:
+ explicit ObjectReceiver(const QuicClock* clock) : clock_(clock) {}
+
+ void OnReply(const FullTrackName& full_track_name,
+ std::optional<absl::string_view> error_reason_phrase) override {
+ QUICHE_CHECK(full_track_name == TrackName());
+ QUICHE_CHECK(!error_reason_phrase.has_value()) << *error_reason_phrase;
+ }
+
+ void OnObjectFragment(const FullTrackName& full_track_name,
+ uint64_t group_sequence, uint64_t object_sequence,
+ uint64_t /*object_send_order*/,
+ MoqtForwardingPreference /*forwarding_preference*/,
+ absl::string_view object,
+ bool end_of_message) override {
+ QUICHE_DCHECK(full_track_name == TrackName());
+
+ // Buffer and assemble partially available objects.
+ // TODO: this logic should be factored out. Also, this should take advantage
+ // of the fact that in the current MoQT, the object size is known in
+ // advance.
+ FullSequence sequence{group_sequence, object_sequence};
+ if (!end_of_message) {
+ auto [it, unused] = partial_objects_.try_emplace(sequence);
+ it->second.append(object);
+ return;
+ }
+ auto it = partial_objects_.find(sequence);
+ if (it == partial_objects_.end()) {
+ OnFullObject(sequence, object);
+ return;
+ }
+ std::string full_object = std::move(it->second);
+ full_object.append(object);
+ partial_objects_.erase(it);
+ OnFullObject(sequence, full_object);
+ }
+
+ void OnFullObject(FullSequence sequence, absl::string_view payload) {
+ QUICHE_CHECK_GE(payload.size(), 8u);
+ quiche::QuicheDataReader reader(payload);
+ uint64_t time_us;
+ reader.ReadUInt64(&time_us);
+ QuicTime time = QuicTime::Zero() + QuicTimeDelta::FromMicroseconds(time_us);
+ QuicTimeDelta delay = clock_->Now() - time;
+ QUICHE_CHECK_GT(delay, QuicTimeDelta::Zero());
+ QUICHE_DCHECK(absl::c_all_of(reader.ReadRemainingPayload(),
+ [](char c) { return c == 0; }));
+ ++full_objects_received_;
+ }
+
+ size_t full_objects_received() const { return full_objects_received_; }
+
+ private:
+ const QuicClock* clock_ = nullptr;
+ // TODO: figure out when partial objects should be discarded.
+ absl::flat_hash_map<FullSequence, std::string> partial_objects_;
+
+ size_t full_objects_received_ = 0;
+};
+
+// Computes the size of the network queue on the switch.
+constexpr QuicByteCount AdjustedQueueSize(
+ const SimulationParameters& parameters) {
+ if (parameters.network_queue_size > 0) {
+ return parameters.network_queue_size;
+ }
+ QuicByteCount bdp = parameters.bandwidth * parameters.min_rtt;
+ return 2 * bdp;
+}
+
+// Simulates the performance of MoQT transfer under the specified network
+// conditions.
+class MoqtSimulator {
+ public:
+ explicit MoqtSimulator(const SimulationParameters& parameters)
+ : simulator_(quic::QuicRandom::GetInstance()),
+ client_endpoint_(&simulator_, "Client", "Server", kMoqtVersion),
+ server_endpoint_(&simulator_, "Server", "Client", kMoqtVersion),
+ switch_(&simulator_, "Switch", 8, AdjustedQueueSize(parameters)),
+ client_link_(&client_endpoint_, switch_.port(1), kClientLinkBandwidth,
+ parameters.min_rtt * 0.25),
+ server_link_(&server_endpoint_, switch_.port(2), parameters.bandwidth,
+ parameters.min_rtt * 0.25),
+ generator_(&simulator_, "Client generator", client_endpoint_.session(),
+ TrackName(), parameters.keyframe_interval, parameters.fps,
+ parameters.i_to_p_ratio, parameters.bitrate),
+ receiver_(simulator_.GetClock()),
+ parameters_(parameters) {}
+
+ MoqtSession* client_session() { return client_endpoint_.session(); }
+ MoqtSession* server_session() { return server_endpoint_.session(); }
+
+ std::string GetClientSessionCongestionControl() {
+ return quic::CongestionControlTypeToString(
+ client_endpoint_.quic_session()
+ ->connection()
+ ->sent_packet_manager()
+ .GetSendAlgorithm()
+ ->GetCongestionControlType());
+ }
+
+ // Runs the simulation and outputs the results to stdout.
+ void Run() {
+ // Timeout for establishing the connection.
+ constexpr QuicTimeDelta kConnectionTimeout = QuicTimeDelta::FromSeconds(1);
+
+ // Perform the QUIC and the MoQT handshake.
+ client_session()->callbacks().session_established_callback = [this] {
+ client_established_ = true;
+ };
+ server_session()->callbacks().session_established_callback = [this] {
+ server_established_ = true;
+ };
+ client_endpoint_.quic_session()->CryptoConnect();
+ simulator_.RunUntilOrTimeout(
+ [&]() { return client_established_ && server_established_; },
+ kConnectionTimeout);
+ QUICHE_CHECK(client_established_) << "Client failed to establish session";
+ QUICHE_CHECK(server_established_) << "Server failed to establish session";
+
+ // The simulation is started as follows. At t=0:
+ // (1) The server issues a subscribe request.
+ // (2) The client starts immediately generating data. At this point, the
+ // server does not yet have an active subscription, so the client has
+ // some catching up to do.
+ client_session()->AddLocalTrack(
+ TrackName(), MoqtForwardingPreference::kGroup, &generator_.queue());
+ generator_.Start();
+ server_session()->SubscribeCurrentGroup(TrackName().track_namespace,
+ TrackName().track_name, &receiver_);
+ simulator_.RunFor(parameters_.duration);
+
+ // At the end, we wait for eight RTTs until the connection settles down.
+ generator_.Stop();
+ simulator_.RunFor(QuicTimeDelta(
+ 8 * client_endpoint_.quic_session()->GetSessionStats().smoothed_rtt));
+
+ std::cout << "Ran simulation for " << parameters_.duration << std::endl;
+ std::cout << "Congestion control used : "
+ << GetClientSessionCongestionControl() << std::endl;
+ std::cout << "Objects sent: " << generator_.total_objects_sent()
+ << std::endl;
+ std::cout << "Objects received: " << receiver_.full_objects_received()
+ << std::endl;
+ }
+
+ private:
+ Simulator simulator_;
+ MoqtClientEndpoint client_endpoint_;
+ MoqtServerEndpoint server_endpoint_;
+ quic::simulator::Switch switch_;
+ quic::simulator::SymmetricLink client_link_;
+ quic::simulator::SymmetricLink server_link_;
+ ObjectGenerator generator_;
+ ObjectReceiver receiver_;
+ SimulationParameters parameters_;
+
+ bool client_established_ = false;
+ bool server_established_ = false;
+};
+
+} // namespace
+} // namespace moqt::test
+
+DEFINE_QUICHE_COMMAND_LINE_FLAG(
+ uint64_t, bandwidth,
+ moqt::test::SimulationParameters().bandwidth.ToKBitsPerSecond(),
+ "Bandwidth of the simulated link, in kilobits per second.");
+
+int main(int argc, char** argv) {
+ moqt::test::SimulationParameters parameters;
+ quiche::QuicheParseCommandLineFlags("moqt_simulator", argc, argv);
+ parameters.bandwidth = quic::QuicBandwidth::FromKBitsPerSecond(
+ quiche::GetQuicheCommandLineFlag(FLAGS_bandwidth));
+
+ moqt::test::MoqtSimulator simulator(parameters);
+ simulator.Run();
+ return 0;
+}
diff --git a/quiche/quic/test_tools/simulator/quic_endpoint_base.cc b/quiche/quic/test_tools/simulator/quic_endpoint_base.cc
index 78d285b..42d5980 100644
--- a/quiche/quic/test_tools/simulator/quic_endpoint_base.cc
+++ b/quiche/quic/test_tools/simulator/quic_endpoint_base.cc
@@ -14,6 +14,7 @@
#include "quiche/quic/core/crypto/crypto_handshake_message.h"
#include "quiche/quic/core/crypto/crypto_protocol.h"
#include "quiche/quic/core/quic_connection.h"
+#include "quiche/quic/core/quic_connection_id.h"
#include "quiche/quic/core/quic_data_writer.h"
#include "quiche/quic/platform/api/quic_test_output.h"
#include "quiche/quic/test_tools/quic_connection_peer.h"
@@ -65,7 +66,8 @@
kMaxOutgoingPacketSize * kTxQueueSize),
connection_(nullptr),
write_blocked_count_(0),
- drop_next_packet_(false) {
+ drop_next_packet_(false),
+ connection_id_generator_(kQuicDefaultConnectionIdLength) {
nic_tx_queue_.set_listener_interface(this);
}
diff --git a/quiche/quic/test_tools/simulator/quic_endpoint_base.h b/quiche/quic/test_tools/simulator/quic_endpoint_base.h
index fe753d5..336b2f9 100644
--- a/quiche/quic/test_tools/simulator/quic_endpoint_base.h
+++ b/quiche/quic/test_tools/simulator/quic_endpoint_base.h
@@ -10,12 +10,12 @@
#include "absl/container/flat_hash_map.h"
#include "quiche/quic/core/crypto/null_decrypter.h"
#include "quiche/quic/core/crypto/null_encrypter.h"
+#include "quiche/quic/core/deterministic_connection_id_generator.h"
#include "quiche/quic/core/quic_connection.h"
#include "quiche/quic/core/quic_packet_writer.h"
#include "quiche/quic/core/quic_packets.h"
#include "quiche/quic/core/quic_stream_frame_data_producer.h"
#include "quiche/quic/core/quic_trace_visitor.h"
-#include "quiche/quic/test_tools/mock_connection_id_generator.h"
#include "quiche/quic/test_tools/simple_session_notifier.h"
#include "quiche/quic/test_tools/simulator/link.h"
#include "quiche/quic/test_tools/simulator/queue.h"
@@ -131,7 +131,7 @@
std::unique_ptr<QuicTraceVisitor> trace_visitor_;
- test::MockConnectionIdGenerator connection_id_generator_;
+ DeterministicConnectionIdGenerator connection_id_generator_;
};
// Multiplexes multiple connections at the same host on the network.
