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/*
* Copyright (c) 2016 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 "modules/congestion_controller/goog_cc/delay_based_bwe.h"
#include <string>
#include "api/transport/network_types.h"
#include "modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator.h"
#include "modules/congestion_controller/goog_cc/delay_based_bwe_unittest_helper.h"
#include "system_wrappers/include/clock.h"
#include "test/gtest.h"
namespace webrtc {
namespace {
constexpr int kNumProbesCluster0 = 5;
constexpr int kNumProbesCluster1 = 8;
const PacedPacketInfo kPacingInfo0(0, kNumProbesCluster0, 2000);
const PacedPacketInfo kPacingInfo1(1, kNumProbesCluster1, 4000);
constexpr float kTargetUtilizationFraction = 0.95f;
} // namespace
TEST_F(DelayBasedBweTest, ProbeDetection) {
int64_t now_ms = clock_.TimeInMilliseconds();
// First burst sent at 8 * 1000 / 10 = 800 kbps.
for (int i = 0; i < kNumProbesCluster0; ++i) {
clock_.AdvanceTimeMilliseconds(10);
now_ms = clock_.TimeInMilliseconds();
IncomingFeedback(now_ms, now_ms, 1000, kPacingInfo0);
}
EXPECT_TRUE(bitrate_observer_.updated());
// Second burst sent at 8 * 1000 / 5 = 1600 kbps.
for (int i = 0; i < kNumProbesCluster1; ++i) {
clock_.AdvanceTimeMilliseconds(5);
now_ms = clock_.TimeInMilliseconds();
IncomingFeedback(now_ms, now_ms, 1000, kPacingInfo1);
}
EXPECT_TRUE(bitrate_observer_.updated());
EXPECT_GT(bitrate_observer_.latest_bitrate(), 1500000u);
}
TEST_F(DelayBasedBweTest, ProbeDetectionNonPacedPackets) {
int64_t now_ms = clock_.TimeInMilliseconds();
// First burst sent at 8 * 1000 / 10 = 800 kbps, but with every other packet
// not being paced which could mess things up.
for (int i = 0; i < kNumProbesCluster0; ++i) {
clock_.AdvanceTimeMilliseconds(5);
now_ms = clock_.TimeInMilliseconds();
IncomingFeedback(now_ms, now_ms, 1000, kPacingInfo0);
// Non-paced packet, arriving 5 ms after.
clock_.AdvanceTimeMilliseconds(5);
IncomingFeedback(now_ms, now_ms, 100, PacedPacketInfo());
}
EXPECT_TRUE(bitrate_observer_.updated());
EXPECT_GT(bitrate_observer_.latest_bitrate(), 800000u);
}
TEST_F(DelayBasedBweTest, ProbeDetectionFasterArrival) {
int64_t now_ms = clock_.TimeInMilliseconds();
// First burst sent at 8 * 1000 / 10 = 800 kbps.
// Arriving at 8 * 1000 / 5 = 1600 kbps.
int64_t send_time_ms = 0;
for (int i = 0; i < kNumProbesCluster0; ++i) {
clock_.AdvanceTimeMilliseconds(1);
send_time_ms += 10;
now_ms = clock_.TimeInMilliseconds();
IncomingFeedback(now_ms, send_time_ms, 1000, kPacingInfo0);
}
EXPECT_FALSE(bitrate_observer_.updated());
}
TEST_F(DelayBasedBweTest, ProbeDetectionSlowerArrival) {
int64_t now_ms = clock_.TimeInMilliseconds();
// First burst sent at 8 * 1000 / 5 = 1600 kbps.
// Arriving at 8 * 1000 / 7 = 1142 kbps.
// Since the receive rate is significantly below the send rate, we expect to
// use 95% of the estimated capacity.
int64_t send_time_ms = 0;
for (int i = 0; i < kNumProbesCluster1; ++i) {
clock_.AdvanceTimeMilliseconds(7);
send_time_ms += 5;
now_ms = clock_.TimeInMilliseconds();
IncomingFeedback(now_ms, send_time_ms, 1000, kPacingInfo1);
}
EXPECT_TRUE(bitrate_observer_.updated());
EXPECT_NEAR(bitrate_observer_.latest_bitrate(),
kTargetUtilizationFraction * 1140000u, 10000u);
}
TEST_F(DelayBasedBweTest, ProbeDetectionSlowerArrivalHighBitrate) {
int64_t now_ms = clock_.TimeInMilliseconds();
// Burst sent at 8 * 1000 / 1 = 8000 kbps.
// Arriving at 8 * 1000 / 2 = 4000 kbps.
// Since the receive rate is significantly below the send rate, we expect to
// use 95% of the estimated capacity.
int64_t send_time_ms = 0;
for (int i = 0; i < kNumProbesCluster1; ++i) {
clock_.AdvanceTimeMilliseconds(2);
send_time_ms += 1;
now_ms = clock_.TimeInMilliseconds();
IncomingFeedback(now_ms, send_time_ms, 1000, kPacingInfo1);
}
EXPECT_TRUE(bitrate_observer_.updated());
EXPECT_NEAR(bitrate_observer_.latest_bitrate(),
kTargetUtilizationFraction * 4000000u, 10000u);
}
TEST_F(DelayBasedBweTest, GetExpectedBwePeriodMs) {
auto default_interval = bitrate_estimator_->GetExpectedBwePeriod();
EXPECT_GT(default_interval.ms(), 0);
CapacityDropTestHelper(1, true, 333, 0);
auto interval = bitrate_estimator_->GetExpectedBwePeriod();
EXPECT_GT(interval.ms(), 0);
EXPECT_NE(interval.ms(), default_interval.ms());
}
TEST_F(DelayBasedBweTest, InitialBehavior) {
InitialBehaviorTestHelper(730000);
}
TEST_F(DelayBasedBweTest, RateIncreaseReordering) {
RateIncreaseReorderingTestHelper(730000);
}
TEST_F(DelayBasedBweTest, RateIncreaseRtpTimestamps) {
RateIncreaseRtpTimestampsTestHelper(622);
}
TEST_F(DelayBasedBweTest, CapacityDropOneStream) {
CapacityDropTestHelper(1, false, 300, 0);
}
TEST_F(DelayBasedBweTest, CapacityDropPosOffsetChange) {
CapacityDropTestHelper(1, false, 867, 30000);
}
TEST_F(DelayBasedBweTest, CapacityDropNegOffsetChange) {
CapacityDropTestHelper(1, false, 933, -30000);
}
TEST_F(DelayBasedBweTest, CapacityDropOneStreamWrap) {
CapacityDropTestHelper(1, true, 333, 0);
}
TEST_F(DelayBasedBweTest, TestTimestampGrouping) {
TestTimestampGroupingTestHelper();
}
TEST_F(DelayBasedBweTest, TestShortTimeoutAndWrap) {
// Simulate a client leaving and rejoining the call after 35 seconds. This
// will make abs send time wrap, so if streams aren't timed out properly
// the next 30 seconds of packets will be out of order.
TestWrappingHelper(35);
}
TEST_F(DelayBasedBweTest, TestLongTimeoutAndWrap) {
// Simulate a client leaving and rejoining the call after some multiple of
// 64 seconds later. This will cause a zero difference in abs send times due
// to the wrap, but a big difference in arrival time, if streams aren't
// properly timed out.
TestWrappingHelper(10 * 64);
}
TEST_F(DelayBasedBweTest, TestInitialOveruse) {
const DataRate kStartBitrate = DataRate::KilobitsPerSec(300);
const DataRate kInitialCapacity = DataRate::KilobitsPerSec(200);
const uint32_t kDummySsrc = 0;
// High FPS to ensure that we send a lot of packets in a short time.
const int kFps = 90;
stream_generator_->AddStream(new test::RtpStream(kFps, kStartBitrate.bps()));
stream_generator_->set_capacity_bps(kInitialCapacity.bps());
// Needed to initialize the AimdRateControl.
bitrate_estimator_->SetStartBitrate(kStartBitrate);
// Produce 30 frames (in 1/3 second) and give them to the estimator.
int64_t bitrate_bps = kStartBitrate.bps();
bool seen_overuse = false;
for (int i = 0; i < 30; ++i) {
bool overuse = GenerateAndProcessFrame(kDummySsrc, bitrate_bps);
// The purpose of this test is to ensure that we back down even if we don't
// have any acknowledged bitrate estimate yet. Hence, if the test works
// as expected, we should not have a measured bitrate yet.
EXPECT_FALSE(acknowledged_bitrate_estimator_->bitrate().has_value());
if (overuse) {
EXPECT_TRUE(bitrate_observer_.updated());
EXPECT_NEAR(bitrate_observer_.latest_bitrate(), kStartBitrate.bps() / 2,
15000);
bitrate_bps = bitrate_observer_.latest_bitrate();
seen_overuse = true;
break;
} else if (bitrate_observer_.updated()) {
bitrate_bps = bitrate_observer_.latest_bitrate();
bitrate_observer_.Reset();
}
}
EXPECT_TRUE(seen_overuse);
EXPECT_NEAR(bitrate_observer_.latest_bitrate(), kStartBitrate.bps() / 2,
15000);
}
TEST_F(DelayBasedBweTest, TestTimestampPrecisionHandling) {
// This test does some basic checks to make sure that timestamps with higher
// than millisecond precision are handled properly and do not cause any
// problems in the estimator. Specifically, previously reported in
// webrtc:14023 and described in more details there, the rounding to the
// nearest milliseconds caused discrepancy in the accumulated delay. This lead
// to false-positive overuse detection.
// Technical details of the test:
// Send times(ms): 0.000, 9.725, 20.000, 29.725, 40.000, 49.725, ...
// Recv times(ms): 0.500, 10.000, 20.500, 30.000, 40.500, 50.000, ...
// Send deltas(ms): 9.750, 10.250, 9.750, 10.250, 9.750, ...
// Recv deltas(ms): 9.500, 10.500, 9.500, 10.500, 9.500, ...
// There is no delay building up between the send times and the receive times,
// therefore this case should never lead to an overuse detection. However, if
// the time deltas were accidentally rounded to the nearest milliseconds, then
// all the send deltas would be equal to 10ms while some recv deltas would
// round up to 11ms which would lead in a false illusion of delay build up.
uint32_t last_bitrate = bitrate_observer_.latest_bitrate();
for (int i = 0; i < 1000; ++i) {
clock_.AdvanceTimeMicroseconds(500);
IncomingFeedback(clock_.CurrentTime(),
clock_.CurrentTime() - TimeDelta::Micros(500), 1000,
PacedPacketInfo());
clock_.AdvanceTimeMicroseconds(9500);
IncomingFeedback(clock_.CurrentTime(),
clock_.CurrentTime() - TimeDelta::Micros(250), 1000,
PacedPacketInfo());
clock_.AdvanceTimeMicroseconds(10000);
// The bitrate should never decrease in this test.
EXPECT_LE(last_bitrate, bitrate_observer_.latest_bitrate());
last_bitrate = bitrate_observer_.latest_bitrate();
}
}
class DelayBasedBweTestWithBackoffTimeoutExperiment : public DelayBasedBweTest {
public:
DelayBasedBweTestWithBackoffTimeoutExperiment()
: DelayBasedBweTest(
"WebRTC-BweAimdRateControlConfig/initial_backoff_interval:200ms/") {
}
};
// This test subsumes and improves DelayBasedBweTest.TestInitialOveruse above.
TEST_F(DelayBasedBweTestWithBackoffTimeoutExperiment, TestInitialOveruse) {
const DataRate kStartBitrate = DataRate::KilobitsPerSec(300);
const DataRate kInitialCapacity = DataRate::KilobitsPerSec(200);
const uint32_t kDummySsrc = 0;
// High FPS to ensure that we send a lot of packets in a short time.
const int kFps = 90;
stream_generator_->AddStream(new test::RtpStream(kFps, kStartBitrate.bps()));
stream_generator_->set_capacity_bps(kInitialCapacity.bps());
// Needed to initialize the AimdRateControl.
bitrate_estimator_->SetStartBitrate(kStartBitrate);
// Produce 30 frames (in 1/3 second) and give them to the estimator.
int64_t bitrate_bps = kStartBitrate.bps();
bool seen_overuse = false;
for (int frames = 0; frames < 30 && !seen_overuse; ++frames) {
bool overuse = GenerateAndProcessFrame(kDummySsrc, bitrate_bps);
// The purpose of this test is to ensure that we back down even if we don't
// have any acknowledged bitrate estimate yet. Hence, if the test works
// as expected, we should not have a measured bitrate yet.
EXPECT_FALSE(acknowledged_bitrate_estimator_->bitrate().has_value());
if (overuse) {
EXPECT_TRUE(bitrate_observer_.updated());
EXPECT_NEAR(bitrate_observer_.latest_bitrate(), kStartBitrate.bps() / 2,
15000);
bitrate_bps = bitrate_observer_.latest_bitrate();
seen_overuse = true;
} else if (bitrate_observer_.updated()) {
bitrate_bps = bitrate_observer_.latest_bitrate();
bitrate_observer_.Reset();
}
}
EXPECT_TRUE(seen_overuse);
// Continue generating an additional 15 frames (equivalent to 167 ms) and
// verify that we don't back down further.
for (int frames = 0; frames < 15 && seen_overuse; ++frames) {
bool overuse = GenerateAndProcessFrame(kDummySsrc, bitrate_bps);
EXPECT_FALSE(overuse);
if (bitrate_observer_.updated()) {
bitrate_bps = bitrate_observer_.latest_bitrate();
EXPECT_GE(bitrate_bps, kStartBitrate.bps() / 2 - 15000);
EXPECT_LE(bitrate_bps, kInitialCapacity.bps() + 15000);
bitrate_observer_.Reset();
}
}
}
} // namespace webrtc