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/*
* Copyright 2022 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/network/simulated_network.h"
#include <algorithm>
#include <cstdint>
#include <map>
#include <optional>
#include <set>
#include <vector>
#include "absl/algorithm/container.h"
#include "api/test/simulated_network.h"
#include "api/units/data_rate.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "test/gmock.h"
#include "test/gtest.h"
namespace webrtc {
namespace {
using ::testing::ElementsAre;
using ::testing::MockFunction;
using ::testing::SizeIs;
PacketInFlightInfo PacketWithSize(size_t size) {
return PacketInFlightInfo(/*size=*/size, /*send_time_us=*/0, /*packet_id=*/1);
}
TEST(SimulatedNetworkTest, NextDeliveryTimeIsUnknownOnEmptyNetwork) {
SimulatedNetwork network = SimulatedNetwork({});
EXPECT_EQ(network.NextDeliveryTimeUs(), absl::nullopt);
}
TEST(SimulatedNetworkTest, EnqueueFirstPacketOnNetworkWithInfiniteCapacity) {
// A packet of 1 kB that gets enqueued on a network with infinite capacity
// should be ready to exit the network immediately.
SimulatedNetwork network = SimulatedNetwork({});
ASSERT_TRUE(network.EnqueuePacket(PacketWithSize(1'000)));
EXPECT_EQ(network.NextDeliveryTimeUs(), 0);
}
TEST(SimulatedNetworkTest, EnqueueFirstPacketOnNetworkWithLimitedCapacity) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps capacity
// should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(PacketWithSize(125)));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
}
TEST(SimulatedNetworkTest,
EnqueuePacketsButNextDeliveryIsBasedOnFirstEnqueuedPacket) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps capacity
// should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1)));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// Enqueuing another packet after 100 us doesn't change the next delivery
// time.
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/100, /*packet_id=*/2)));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// Enqueuing another packet after 2 seconds doesn't change the next delivery
// time since the first packet has not left the network yet.
ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
/*size=*/125, /*send_time_us=*/TimeDelta::Seconds(2).us(),
/*packet_id=*/3)));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
}
TEST(SimulatedNetworkTest, EnqueueFailsWhenQueueLengthIsReached) {
SimulatedNetwork network =
SimulatedNetwork({.queue_length_packets = 1,
.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1)));
// Until there is 1 packet in the queue, no other packets can be enqueued,
// the only way to make space for new packets is calling
// DequeueDeliverablePackets at a time greater than or equal to
// NextDeliveryTimeUs.
EXPECT_FALSE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125,
/*send_time_us=*/TimeDelta::Seconds(0.5).us(),
/*packet_id=*/2)));
// Even if the send_time_us is after NextDeliveryTimeUs, it is still not
// possible to enqueue a new packet since the client didn't deque any packet
// from the queue (in this case the client is introducing unbounded delay but
// the network cannot do anything about it).
EXPECT_FALSE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125,
/*send_time_us=*/TimeDelta::Seconds(2).us(),
/*packet_id=*/3)));
}
TEST(SimulatedNetworkTest, PacketOverhead) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps capacity
// should be ready to exit the network in 1 second, but since there is an
// overhead per packet of 125 bytes, it will exit the network after 2 seconds.
SimulatedNetwork network = SimulatedNetwork(
{.link_capacity = DataRate::KilobitsPerSec(1), .packet_overhead = 125});
ASSERT_TRUE(network.EnqueuePacket(PacketWithSize(125)));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(2).us());
}
TEST(SimulatedNetworkTest,
DequeueDeliverablePacketsLeavesPacketsInCapacityLink) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps capacity
// should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1)));
// Enqueue another packet of 125 bytes (this one should exit after 2 seconds).
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125,
/*send_time_us=*/TimeDelta::Seconds(1).us(),
/*packet_id=*/2)));
// The first packet will exit after 1 second, so that is the next delivery
// time.
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// After 1 seconds, we collect the delivered packets...
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(1).us());
ASSERT_EQ(delivered_packets.size(), 1ul);
EXPECT_EQ(delivered_packets[0].packet_id, 1ul);
EXPECT_EQ(delivered_packets[0].receive_time_us, TimeDelta::Seconds(1).us());
// ... And after the first enqueued packet has left the network, the next
// delivery time reflects the delivery time of the next packet.
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(2).us());
}
TEST(SimulatedNetworkTest,
DequeueDeliverablePacketsAppliesConfigChangesToCapacityLink) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps capacity
// should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
const PacketInFlightInfo packet_1 =
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1);
ASSERT_TRUE(network.EnqueuePacket(packet_1));
// Enqueue another packet of 125 bytes with send time 1 second so this should
// exit after 2 seconds.
PacketInFlightInfo packet_2 =
PacketInFlightInfo(/*size=*/125,
/*send_time_us=*/TimeDelta::Seconds(1).us(),
/*packet_id=*/2);
ASSERT_TRUE(network.EnqueuePacket(packet_2));
// The first packet will exit after 1 second, so that is the next delivery
// time.
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// Since the link capacity changes from 1 kbps to 10 kbps, packets will take
// 100 ms each to leave the network.
network.SetConfig({.link_capacity = DataRate::KilobitsPerSec(10)});
// The next delivery time doesn't change (it will be updated, if needed at
// DequeueDeliverablePackets time).
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// Getting the first enqueued packet after 100 ms.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Millis(100).us());
ASSERT_EQ(delivered_packets.size(), 1ul);
EXPECT_THAT(delivered_packets,
ElementsAre(PacketDeliveryInfo(
/*source=*/packet_1,
/*receive_time_us=*/TimeDelta::Millis(100).us())));
// Getting the second enqueued packet that cannot be delivered before its send
// time, hence it will be delivered after 1.1 seconds.
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Millis(1100).us());
delivered_packets = network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Millis(1100).us());
ASSERT_EQ(delivered_packets.size(), 1ul);
EXPECT_THAT(delivered_packets,
ElementsAre(PacketDeliveryInfo(
/*source=*/packet_2,
/*receive_time_us=*/TimeDelta::Millis(1100).us())));
}
TEST(SimulatedNetworkTest,
SetConfigUpdateNextDeliveryTimeIfLinkCapacityChange) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps capacity
// should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
MockFunction<void()> delivery_time_changed_callback;
network.RegisterDeliveryTimeChangedCallback(
delivery_time_changed_callback.AsStdFunction());
const PacketInFlightInfo packet_1 =
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1);
ASSERT_TRUE(network.EnqueuePacket(packet_1));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// Since the link capacity changes from 1 kbps to 10 kbps, packets will take
// 100 ms each to leave the network. After 500ms, half the packet should have
// gone through.
EXPECT_CALL(delivery_time_changed_callback, Call).WillOnce([&]() {
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Millis(500 + 50).us());
});
network.SetConfig({.link_capacity = DataRate::KilobitsPerSec(10)},
/*config_update_time*/ Timestamp::Millis(500));
}
TEST(SimulatedNetworkTest,
SetConfigUpdateNextDeliveryTimeIfLinkCapacityChangeFromZero) {
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::Zero()});
MockFunction<void()> delivery_time_changed_callback;
network.RegisterDeliveryTimeChangedCallback(
delivery_time_changed_callback.AsStdFunction());
const PacketInFlightInfo packet_1 =
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1);
const PacketInFlightInfo packet_2 =
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/2);
ASSERT_TRUE(network.EnqueuePacket(packet_1));
ASSERT_TRUE(network.EnqueuePacket(packet_2));
EXPECT_FALSE(network.NextDeliveryTimeUs().has_value());
// The link capacity changes from 0 kbps to 10 kbps during 10ms 1/10th of the
// packet will be transmitted. (The packet would take 100ms to go through the
// network at 10kbps.)
::testing::Sequence s;
EXPECT_CALL(delivery_time_changed_callback, Call)
.InSequence(s)
.WillOnce([&]() {
EXPECT_EQ(network.NextDeliveryTimeUs(),
TimeDelta::Millis(500 + 100).us());
});
EXPECT_CALL(delivery_time_changed_callback, Call)
.InSequence(s)
.WillOnce(
[&]() { EXPECT_FALSE(network.NextDeliveryTimeUs().has_value()); });
EXPECT_CALL(delivery_time_changed_callback, Call)
.InSequence(s)
.WillOnce([&]() {
EXPECT_EQ(network.NextDeliveryTimeUs(),
TimeDelta::Millis(610 + 90).us());
});
network.SetConfig({.link_capacity = DataRate::KilobitsPerSec(10)},
/*config_update_time*/ Timestamp::Millis(500));
network.SetConfig({.link_capacity = DataRate::Zero()},
/*config_update_time*/ Timestamp::Millis(510));
network.SetConfig({.link_capacity = DataRate::KilobitsPerSec(10)},
/*config_update_time*/ Timestamp::Millis(610));
}
TEST(SimulatedNetworkTest, SetConfigUpdateQueueDelayAfterDelivery) {
// A packet of 125 bytes that gets enqueued on a network with 1000 kbps
// capacity should be ready to exit the narrow section in 1 ms.
SimulatedNetwork network =
SimulatedNetwork({.queue_delay_ms = 1000,
.link_capacity = DataRate::KilobitsPerSec(1000)});
MockFunction<void()> delivery_time_changed_callback;
network.RegisterDeliveryTimeChangedCallback(
delivery_time_changed_callback.AsStdFunction());
EXPECT_CALL(delivery_time_changed_callback, Call).Times(0);
const PacketInFlightInfo packet_1 =
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1);
ASSERT_TRUE(network.EnqueuePacket(packet_1));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Millis(1).us());
// But no packets is actually delivered. Only moved to the delay link.
EXPECT_TRUE(network
.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Millis(1).us())
.empty());
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Millis(1000 + 1).us());
// Changing the queue time does not change the next delivery time.
network.SetConfig(
{.queue_delay_ms = 1, .link_capacity = DataRate::KilobitsPerSec(100)},
/*config_update_time*/ Timestamp::Millis(500));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Millis(1000 + 1).us());
// A new packet require NextDeliveryTimeUs to change since the capacity
// change. But does not affect the delivery time of packet_1.
const PacketInFlightInfo packet_2 = PacketInFlightInfo(
/*size=*/125, /*send_time_us=*/TimeDelta::Millis(500).us(),
/*packet_id=*/2);
ASSERT_TRUE(network.EnqueuePacket(packet_2));
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Millis(1000 + 1).us());
// At 100kbps, it will take packet 2 10ms to pass through the narrow section.
// Since delay is lower for packet_2, but reordering is not allowed, both
// packets are delivered at the same time.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Millis(1000 + 1).us());
ASSERT_THAT(delivered_packets, SizeIs(2));
EXPECT_EQ(delivered_packets[0].receive_time_us,
delivered_packets[1].receive_time_us);
}
TEST(SimulatedNetworkTest, NetworkEmptyAfterLastPacketDequeued) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps
// capacity should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(PacketWithSize(125)));
// Collecting all the delivered packets ...
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(1).us());
EXPECT_EQ(delivered_packets.size(), 1ul);
// ... leaves the network empty.
EXPECT_EQ(network.NextDeliveryTimeUs(), absl::nullopt);
}
TEST(SimulatedNetworkTest, DequeueDeliverablePacketsOnLateCall) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps
// capacity should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1)));
// Enqueue another packet of 125 bytes with send time 1 second so this
// should exit after 2 seconds.
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125,
/*send_time_us=*/TimeDelta::Seconds(1).us(),
/*packet_id=*/2)));
// Collecting delivered packets after 3 seconds will result in the delivery
// of both the enqueued packets.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(3).us());
EXPECT_EQ(delivered_packets.size(), 2ul);
}
TEST(SimulatedNetworkTest,
DequeueDeliverablePacketsOnEarlyCallReturnsNoPackets) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps
// capacity should be ready to exit the network in 1 second.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(PacketWithSize(125)));
// Collecting delivered packets after 0.5 seconds will result in the
// delivery of 0 packets.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(0.5).us());
EXPECT_EQ(delivered_packets.size(), 0ul);
// Since the first enqueued packet was supposed to exit after 1 second.
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
}
TEST(SimulatedNetworkTest, QueueDelayMsWithoutStandardDeviation) {
// A packet of 125 bytes that gets enqueued on a network with 1 kbps
// capacity should be ready to exit the network in 1 second.
SimulatedNetwork network = SimulatedNetwork(
{.queue_delay_ms = 100, .link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(PacketWithSize(125)));
// The next delivery time is still 1 second even if there are 100 ms of
// extra delay but this will be applied at DequeueDeliverablePackets time.
ASSERT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// Since all packets are delayed by 100 ms, after 1 second, no packets will
// exit the network.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(1).us());
EXPECT_EQ(delivered_packets.size(), 0ul);
// And the updated next delivery time takes into account the extra delay of
// 100 ms so the first packet in the network will be delivered after 1.1
// seconds.
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Millis(1100).us());
delivered_packets = network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Millis(1100).us());
EXPECT_EQ(delivered_packets.size(), 1ul);
}
TEST(SimulatedNetworkTest,
QueueDelayMsWithStandardDeviationAndReorderNotAllowed) {
SimulatedNetwork network =
SimulatedNetwork({.queue_delay_ms = 100,
.delay_standard_deviation_ms = 90,
.link_capacity = DataRate::KilobitsPerSec(1),
.allow_reordering = false});
// A packet of 125 bytes that gets enqueued on a network with 1 kbps
// capacity should be ready to exit the network in 1 second.
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1)));
// But 3 more packets of size 1 byte are enqueued at the same time.
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/1, /*send_time_us=*/0, /*packet_id=*/2)));
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/1, /*send_time_us=*/0, /*packet_id=*/3)));
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/1, /*send_time_us=*/0, /*packet_id=*/4)));
// After 5 seconds all of them exit the network.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(5).us());
ASSERT_EQ(delivered_packets.size(), 4ul);
// And they are still in order even if the delay was applied.
EXPECT_EQ(delivered_packets[0].packet_id, 1ul);
EXPECT_EQ(delivered_packets[1].packet_id, 2ul);
EXPECT_GE(delivered_packets[1].receive_time_us,
delivered_packets[0].receive_time_us);
EXPECT_EQ(delivered_packets[2].packet_id, 3ul);
EXPECT_GE(delivered_packets[2].receive_time_us,
delivered_packets[1].receive_time_us);
EXPECT_EQ(delivered_packets[3].packet_id, 4ul);
EXPECT_GE(delivered_packets[3].receive_time_us,
delivered_packets[2].receive_time_us);
}
TEST(SimulatedNetworkTest, QueueDelayMsWithStandardDeviationAndReorderAllowed) {
SimulatedNetwork network =
SimulatedNetwork({.queue_delay_ms = 100,
.delay_standard_deviation_ms = 90,
.link_capacity = DataRate::KilobitsPerSec(1),
.allow_reordering = true},
/*random_seed=*/1);
// A packet of 125 bytes that gets enqueued on a network with 1 kbps
// capacity should be ready to exit the network in 1 second.
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1)));
// But 3 more packets of size 1 byte are enqueued at the same time.
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/1, /*send_time_us=*/0, /*packet_id=*/2)));
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/1, /*send_time_us=*/0, /*packet_id=*/3)));
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/1, /*send_time_us=*/0, /*packet_id=*/4)));
// After 5 seconds all of them exit the network.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(5).us());
ASSERT_EQ(delivered_packets.size(), 4ul);
// And they have been reordered accorting to the applied extra delay.
EXPECT_EQ(delivered_packets[0].packet_id, 3ul);
EXPECT_EQ(delivered_packets[1].packet_id, 1ul);
EXPECT_GE(delivered_packets[1].receive_time_us,
delivered_packets[0].receive_time_us);
EXPECT_EQ(delivered_packets[2].packet_id, 2ul);
EXPECT_GE(delivered_packets[2].receive_time_us,
delivered_packets[1].receive_time_us);
EXPECT_EQ(delivered_packets[3].packet_id, 4ul);
EXPECT_GE(delivered_packets[3].receive_time_us,
delivered_packets[2].receive_time_us);
}
TEST(SimulatedNetworkTest, PacketLoss) {
// On a network with 50% probability of packet loss ...
SimulatedNetwork network =
SimulatedNetwork({.loss_percent = 50}, /*random_seed =*/1);
// Enqueueing 8 packets ...
for (int i = 0; i < 8; i++) {
ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
/*size=*/1, /*send_time_us=*/0, /*packet_id=*/i + 1)));
}
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(5).us());
EXPECT_EQ(delivered_packets.size(), 8ul);
// Results in the loss of 4 of them.
int lost_packets = 0;
for (const auto& packet : delivered_packets) {
if (packet.receive_time_us == PacketDeliveryInfo::kNotReceived) {
lost_packets++;
}
}
EXPECT_EQ(lost_packets, 4);
}
TEST(SimulatedNetworkTest, NextDeliveryTimeSetAfterLostPackets) {
// On a network with 50% probablility of packet loss ...
SimulatedNetwork network =
SimulatedNetwork({.queue_delay_ms = 10,
.link_capacity = DataRate::KilobitsPerSec(1000),
.loss_percent = 50},
/*random_seed =*/1);
// Enqueueing 8 packets at the same time. It should take 1ms to pass through
// the capacity limited section per packet, it total adding 8ms delay to the
// last packet. Since queue delay is 10ms, multiple packets will be in the
// delay queue at the same time.
for (int i = 0; i < 8; i++) {
ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
/*size=*/125, /*send_time_us=*/0, /*packet_id=*/i + 1)));
}
int64_t time_us = 0;
std::vector<PacketDeliveryInfo> delivered_packets;
// This assumes first packet is lost and last packet is delivered....
while (delivered_packets.size() != 8) {
ASSERT_TRUE(network.NextDeliveryTimeUs().has_value());
time_us = *network.NextDeliveryTimeUs();
std::vector<PacketDeliveryInfo> packets =
network.DequeueDeliverablePackets(time_us);
delivered_packets.insert(delivered_packets.end(), packets.begin(),
packets.end());
}
// Results in the loss of 4 of them.
int lost_packets = 0;
int received_packets = 0;
for (const auto& packet : delivered_packets) {
if (packet.receive_time_us == PacketDeliveryInfo::kNotReceived) {
lost_packets++;
} else {
received_packets++;
}
}
EXPECT_EQ(delivered_packets.back().receive_time_us,
Timestamp::Millis(10 + 8).us());
EXPECT_EQ(lost_packets, 4);
EXPECT_EQ(received_packets, 4);
}
TEST(SimulatedNetworkTest, PacketLossBurst) {
// On a network with 50% probability of packet loss and an average burst
// loss length of 100 ...
SimulatedNetwork network = SimulatedNetwork(
{.loss_percent = 50, .avg_burst_loss_length = 100}, /*random_seed=*/1);
// Enqueueing 20 packets ...
for (int i = 0; i < 20; i++) {
ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
/*size=*/1, /*send_time_us=*/0, /*packet_id=*/i + 1)));
}
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(5).us());
EXPECT_EQ(delivered_packets.size(), 20ul);
// Results in a burst of lost packets after the first packet lost.
// With the current random seed, the first 12 are not lost, while the
// last 8 are.
int current_packet = 0;
for (const auto& packet : delivered_packets) {
if (current_packet < 12) {
EXPECT_NE(packet.receive_time_us, PacketDeliveryInfo::kNotReceived);
current_packet++;
} else {
EXPECT_EQ(packet.receive_time_us, PacketDeliveryInfo::kNotReceived);
current_packet++;
}
}
}
TEST(SimulatedNetworkTest, PauseTransmissionUntil) {
// 3 packets of 125 bytes that gets enqueued on a network with 1 kbps
// capacity should be ready to exit the network after 1, 2 and 3 seconds
// respectively.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/1)));
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/2)));
ASSERT_TRUE(network.EnqueuePacket(
PacketInFlightInfo(/*size=*/125, /*send_time_us=*/0, /*packet_id=*/3)));
ASSERT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(1).us());
// The network gets paused for 5 seconds, which means that the first packet
// can exit after 5 seconds instead of 1 second.
network.PauseTransmissionUntil(TimeDelta::Seconds(5).us());
// No packets after 1 second.
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(1).us());
EXPECT_EQ(delivered_packets.size(), 0ul);
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(5).us());
// The first packet exits after 5 seconds.
delivered_packets = network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(5).us());
EXPECT_EQ(delivered_packets.size(), 1ul);
// After the first packet is exited, the next delivery time reflects the
// delivery time of the next packet which accounts for the network pause.
EXPECT_EQ(network.NextDeliveryTimeUs(), TimeDelta::Seconds(6).us());
// And 2 seconds after the exit of the first enqueued packet, the following
// 2 packets are also delivered.
delivered_packets = network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(7).us());
EXPECT_EQ(delivered_packets.size(), 2ul);
}
TEST(SimulatedNetworkTest, CongestedNetworkRespectsLinkCapacity) {
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
for (size_t i = 0; i < 1'000; ++i) {
ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
/*size=*/125, /*send_time_us=*/0, /*packet_id=*/i)));
}
PacketDeliveryInfo last_delivered_packet{
PacketInFlightInfo(/*size=*/0, /*send_time_us=*/0, /*packet_id=*/0), 0};
while (network.NextDeliveryTimeUs().has_value()) {
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/network.NextDeliveryTimeUs().value());
if (!delivered_packets.empty()) {
last_delivered_packet = delivered_packets.back();
}
}
// 1000 packets of 1000 bits each will take 1000 seconds to exit a 1 kpbs
// network.
EXPECT_EQ(last_delivered_packet.receive_time_us,
TimeDelta::Seconds(1000).us());
EXPECT_EQ(last_delivered_packet.packet_id, 999ul);
}
TEST(SimulatedNetworkTest, EnqueuePacketWithSubSecondNonMonotonicBehaviour) {
// On multi-core systems, different threads can experience sub-millisecond
// non monothonic behaviour when running on different cores. This test
// checks that when a non monotonic packet enqueue, the network continues to
// work and the out of order packet is sent anyway.
SimulatedNetwork network =
SimulatedNetwork({.link_capacity = DataRate::KilobitsPerSec(1)});
ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
/*size=*/125, /*send_time_us=*/TimeDelta::Seconds(1).us(),
/*packet_id=*/0)));
ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
/*size=*/125, /*send_time_us=*/TimeDelta::Seconds(1).us() - 1,
/*packet_id=*/1)));
std::vector<PacketDeliveryInfo> delivered_packets =
network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(2).us());
ASSERT_EQ(delivered_packets.size(), 1ul);
EXPECT_EQ(delivered_packets[0].packet_id, 0ul);
EXPECT_EQ(delivered_packets[0].receive_time_us, TimeDelta::Seconds(2).us());
delivered_packets = network.DequeueDeliverablePackets(
/*receive_time_us=*/TimeDelta::Seconds(3).us());
ASSERT_EQ(delivered_packets.size(), 1ul);
EXPECT_EQ(delivered_packets[0].packet_id, 1ul);
EXPECT_EQ(delivered_packets[0].receive_time_us, TimeDelta::Seconds(3).us());
}
// TODO(bugs.webrtc.org/14525): Re-enable when the DCHECK will be uncommented
// and the non-monotonic events on real time clock tests is solved/understood.
// TEST(SimulatedNetworkDeathTest, EnqueuePacketExpectMonotonicSendTime) {
// SimulatedNetwork network = SimulatedNetwork({.link_capacity =
// DataRate::KilobitsPerSec(1)});
// ASSERT_TRUE(network.EnqueuePacket(PacketInFlightInfo(
// /*size=*/125, /*send_time_us=*/2'000'000, /*packet_id=*/0)));
// EXPECT_DEATH_IF_SUPPORTED(network.EnqueuePacket(PacketInFlightInfo(
// /*size=*/125, /*send_time_us=*/900'000, /*packet_id=*/1)), "");
// }
} // namespace
} // namespace webrtc