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// Copyright (c) 2016 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.
#include "quic/core/congestion_control/windowed_filter.h"
#include "quic/core/congestion_control/rtt_stats.h"
#include "quic/core/quic_bandwidth.h"
#include "quic/core/quic_packets.h"
#include "quic/platform/api/quic_logging.h"
#include "quic/platform/api/quic_test.h"
namespace quic {
namespace test {
class WindowedFilterTest : public QuicTest {
public:
// Set the window to 99ms, so 25ms is more than a quarter rtt.
WindowedFilterTest()
: windowed_min_rtt_(QuicTime::Delta::FromMilliseconds(99),
QuicTime::Delta::Zero(),
QuicTime::Zero()),
windowed_max_bw_(QuicTime::Delta::FromMilliseconds(99),
QuicBandwidth::Zero(),
QuicTime::Zero()) {}
// Sets up windowed_min_rtt_ to have the following values:
// Best = 20ms, recorded at 25ms
// Second best = 40ms, recorded at 75ms
// Third best = 50ms, recorded at 100ms
void InitializeMinFilter() {
QuicTime now = QuicTime::Zero();
QuicTime::Delta rtt_sample = QuicTime::Delta::FromMilliseconds(10);
for (int i = 0; i < 5; ++i) {
windowed_min_rtt_.Update(rtt_sample, now);
QUIC_VLOG(1) << "i: " << i << " sample: " << rtt_sample.ToMilliseconds()
<< " mins: "
<< " " << windowed_min_rtt_.GetBest().ToMilliseconds() << " "
<< windowed_min_rtt_.GetSecondBest().ToMilliseconds() << " "
<< windowed_min_rtt_.GetThirdBest().ToMilliseconds();
now = now + QuicTime::Delta::FromMilliseconds(25);
rtt_sample = rtt_sample + QuicTime::Delta::FromMilliseconds(10);
}
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(20),
windowed_min_rtt_.GetBest());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(40),
windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(50),
windowed_min_rtt_.GetThirdBest());
}
// Sets up windowed_max_bw_ to have the following values:
// Best = 900 bps, recorded at 25ms
// Second best = 700 bps, recorded at 75ms
// Third best = 600 bps, recorded at 100ms
void InitializeMaxFilter() {
QuicTime now = QuicTime::Zero();
QuicBandwidth bw_sample = QuicBandwidth::FromBitsPerSecond(1000);
for (int i = 0; i < 5; ++i) {
windowed_max_bw_.Update(bw_sample, now);
QUIC_VLOG(1) << "i: " << i << " sample: " << bw_sample.ToBitsPerSecond()
<< " maxs: "
<< " " << windowed_max_bw_.GetBest().ToBitsPerSecond() << " "
<< windowed_max_bw_.GetSecondBest().ToBitsPerSecond() << " "
<< windowed_max_bw_.GetThirdBest().ToBitsPerSecond();
now = now + QuicTime::Delta::FromMilliseconds(25);
bw_sample = bw_sample - QuicBandwidth::FromBitsPerSecond(100);
}
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(900),
windowed_max_bw_.GetBest());
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(700),
windowed_max_bw_.GetSecondBest());
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(600),
windowed_max_bw_.GetThirdBest());
}
protected:
WindowedFilter<QuicTime::Delta,
MinFilter<QuicTime::Delta>,
QuicTime,
QuicTime::Delta>
windowed_min_rtt_;
WindowedFilter<QuicBandwidth,
MaxFilter<QuicBandwidth>,
QuicTime,
QuicTime::Delta>
windowed_max_bw_;
};
namespace {
// Test helper function: updates the filter with a lot of small values in order
// to ensure that it is not susceptible to noise.
void UpdateWithIrrelevantSamples(
WindowedFilter<uint64_t, MaxFilter<uint64_t>, uint64_t, uint64_t>* filter,
uint64_t max_value,
uint64_t time) {
for (uint64_t i = 0; i < 1000; i++) {
filter->Update(i % max_value, time);
}
}
} // namespace
TEST_F(WindowedFilterTest, UninitializedEstimates) {
EXPECT_EQ(QuicTime::Delta::Zero(), windowed_min_rtt_.GetBest());
EXPECT_EQ(QuicTime::Delta::Zero(), windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(QuicTime::Delta::Zero(), windowed_min_rtt_.GetThirdBest());
EXPECT_EQ(QuicBandwidth::Zero(), windowed_max_bw_.GetBest());
EXPECT_EQ(QuicBandwidth::Zero(), windowed_max_bw_.GetSecondBest());
EXPECT_EQ(QuicBandwidth::Zero(), windowed_max_bw_.GetThirdBest());
}
TEST_F(WindowedFilterTest, MonotonicallyIncreasingMin) {
QuicTime now = QuicTime::Zero();
QuicTime::Delta rtt_sample = QuicTime::Delta::FromMilliseconds(10);
windowed_min_rtt_.Update(rtt_sample, now);
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), windowed_min_rtt_.GetBest());
// Gradually increase the rtt samples and ensure the windowed min rtt starts
// rising.
for (int i = 0; i < 6; ++i) {
now = now + QuicTime::Delta::FromMilliseconds(25);
rtt_sample = rtt_sample + QuicTime::Delta::FromMilliseconds(10);
windowed_min_rtt_.Update(rtt_sample, now);
QUIC_VLOG(1) << "i: " << i << " sample: " << rtt_sample.ToMilliseconds()
<< " mins: "
<< " " << windowed_min_rtt_.GetBest().ToMilliseconds() << " "
<< windowed_min_rtt_.GetSecondBest().ToMilliseconds() << " "
<< windowed_min_rtt_.GetThirdBest().ToMilliseconds();
if (i < 3) {
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10),
windowed_min_rtt_.GetBest());
} else if (i == 3) {
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(20),
windowed_min_rtt_.GetBest());
} else if (i < 6) {
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(40),
windowed_min_rtt_.GetBest());
}
}
}
TEST_F(WindowedFilterTest, MonotonicallyDecreasingMax) {
QuicTime now = QuicTime::Zero();
QuicBandwidth bw_sample = QuicBandwidth::FromBitsPerSecond(1000);
windowed_max_bw_.Update(bw_sample, now);
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(1000), windowed_max_bw_.GetBest());
// Gradually decrease the bw samples and ensure the windowed max bw starts
// decreasing.
for (int i = 0; i < 6; ++i) {
now = now + QuicTime::Delta::FromMilliseconds(25);
bw_sample = bw_sample - QuicBandwidth::FromBitsPerSecond(100);
windowed_max_bw_.Update(bw_sample, now);
QUIC_VLOG(1) << "i: " << i << " sample: " << bw_sample.ToBitsPerSecond()
<< " maxs: "
<< " " << windowed_max_bw_.GetBest().ToBitsPerSecond() << " "
<< windowed_max_bw_.GetSecondBest().ToBitsPerSecond() << " "
<< windowed_max_bw_.GetThirdBest().ToBitsPerSecond();
if (i < 3) {
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(1000),
windowed_max_bw_.GetBest());
} else if (i == 3) {
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(900),
windowed_max_bw_.GetBest());
} else if (i < 6) {
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(700),
windowed_max_bw_.GetBest());
}
}
}
TEST_F(WindowedFilterTest, SampleChangesThirdBestMin) {
InitializeMinFilter();
// RTT sample lower than the third-choice min-rtt sets that, but nothing else.
QuicTime::Delta rtt_sample =
windowed_min_rtt_.GetThirdBest() - QuicTime::Delta::FromMilliseconds(5);
// This assert is necessary to avoid triggering -Wstrict-overflow
// See crbug/616957
ASSERT_GT(windowed_min_rtt_.GetThirdBest(),
QuicTime::Delta::FromMilliseconds(5));
// Latest sample was recorded at 100ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(101);
windowed_min_rtt_.Update(rtt_sample, now);
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetThirdBest());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(40),
windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(20), windowed_min_rtt_.GetBest());
}
TEST_F(WindowedFilterTest, SampleChangesThirdBestMax) {
InitializeMaxFilter();
// BW sample higher than the third-choice max sets that, but nothing else.
QuicBandwidth bw_sample =
windowed_max_bw_.GetThirdBest() + QuicBandwidth::FromBitsPerSecond(50);
// Latest sample was recorded at 100ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(101);
windowed_max_bw_.Update(bw_sample, now);
EXPECT_EQ(bw_sample, windowed_max_bw_.GetThirdBest());
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(700),
windowed_max_bw_.GetSecondBest());
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(900), windowed_max_bw_.GetBest());
}
TEST_F(WindowedFilterTest, SampleChangesSecondBestMin) {
InitializeMinFilter();
// RTT sample lower than the second-choice min sets that and also
// the third-choice min.
QuicTime::Delta rtt_sample =
windowed_min_rtt_.GetSecondBest() - QuicTime::Delta::FromMilliseconds(5);
// This assert is necessary to avoid triggering -Wstrict-overflow
// See crbug/616957
ASSERT_GT(windowed_min_rtt_.GetSecondBest(),
QuicTime::Delta::FromMilliseconds(5));
// Latest sample was recorded at 100ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(101);
windowed_min_rtt_.Update(rtt_sample, now);
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetThirdBest());
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(20), windowed_min_rtt_.GetBest());
}
TEST_F(WindowedFilterTest, SampleChangesSecondBestMax) {
InitializeMaxFilter();
// BW sample higher than the second-choice max sets that and also
// the third-choice max.
QuicBandwidth bw_sample =
windowed_max_bw_.GetSecondBest() + QuicBandwidth::FromBitsPerSecond(50);
// Latest sample was recorded at 100ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(101);
windowed_max_bw_.Update(bw_sample, now);
EXPECT_EQ(bw_sample, windowed_max_bw_.GetThirdBest());
EXPECT_EQ(bw_sample, windowed_max_bw_.GetSecondBest());
EXPECT_EQ(QuicBandwidth::FromBitsPerSecond(900), windowed_max_bw_.GetBest());
}
TEST_F(WindowedFilterTest, SampleChangesAllMins) {
InitializeMinFilter();
// RTT sample lower than the first-choice min-rtt sets that and also
// the second and third-choice mins.
QuicTime::Delta rtt_sample =
windowed_min_rtt_.GetBest() - QuicTime::Delta::FromMilliseconds(5);
// This assert is necessary to avoid triggering -Wstrict-overflow
// See crbug/616957
ASSERT_GT(windowed_min_rtt_.GetBest(), QuicTime::Delta::FromMilliseconds(5));
// Latest sample was recorded at 100ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(101);
windowed_min_rtt_.Update(rtt_sample, now);
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetThirdBest());
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetBest());
}
TEST_F(WindowedFilterTest, SampleChangesAllMaxs) {
InitializeMaxFilter();
// BW sample higher than the first-choice max sets that and also
// the second and third-choice maxs.
QuicBandwidth bw_sample =
windowed_max_bw_.GetBest() + QuicBandwidth::FromBitsPerSecond(50);
// Latest sample was recorded at 100ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(101);
windowed_max_bw_.Update(bw_sample, now);
EXPECT_EQ(bw_sample, windowed_max_bw_.GetThirdBest());
EXPECT_EQ(bw_sample, windowed_max_bw_.GetSecondBest());
EXPECT_EQ(bw_sample, windowed_max_bw_.GetBest());
}
TEST_F(WindowedFilterTest, ExpireBestMin) {
InitializeMinFilter();
QuicTime::Delta old_third_best = windowed_min_rtt_.GetThirdBest();
QuicTime::Delta old_second_best = windowed_min_rtt_.GetSecondBest();
QuicTime::Delta rtt_sample =
old_third_best + QuicTime::Delta::FromMilliseconds(5);
// Best min sample was recorded at 25ms, so expiry time is 124ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(125);
windowed_min_rtt_.Update(rtt_sample, now);
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetThirdBest());
EXPECT_EQ(old_third_best, windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(old_second_best, windowed_min_rtt_.GetBest());
}
TEST_F(WindowedFilterTest, ExpireBestMax) {
InitializeMaxFilter();
QuicBandwidth old_third_best = windowed_max_bw_.GetThirdBest();
QuicBandwidth old_second_best = windowed_max_bw_.GetSecondBest();
QuicBandwidth bw_sample =
old_third_best - QuicBandwidth::FromBitsPerSecond(50);
// Best max sample was recorded at 25ms, so expiry time is 124ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(125);
windowed_max_bw_.Update(bw_sample, now);
EXPECT_EQ(bw_sample, windowed_max_bw_.GetThirdBest());
EXPECT_EQ(old_third_best, windowed_max_bw_.GetSecondBest());
EXPECT_EQ(old_second_best, windowed_max_bw_.GetBest());
}
TEST_F(WindowedFilterTest, ExpireSecondBestMin) {
InitializeMinFilter();
QuicTime::Delta old_third_best = windowed_min_rtt_.GetThirdBest();
QuicTime::Delta rtt_sample =
old_third_best + QuicTime::Delta::FromMilliseconds(5);
// Second best min sample was recorded at 75ms, so expiry time is 174ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(175);
windowed_min_rtt_.Update(rtt_sample, now);
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetThirdBest());
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(old_third_best, windowed_min_rtt_.GetBest());
}
TEST_F(WindowedFilterTest, ExpireSecondBestMax) {
InitializeMaxFilter();
QuicBandwidth old_third_best = windowed_max_bw_.GetThirdBest();
QuicBandwidth bw_sample =
old_third_best - QuicBandwidth::FromBitsPerSecond(50);
// Second best max sample was recorded at 75ms, so expiry time is 174ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(175);
windowed_max_bw_.Update(bw_sample, now);
EXPECT_EQ(bw_sample, windowed_max_bw_.GetThirdBest());
EXPECT_EQ(bw_sample, windowed_max_bw_.GetSecondBest());
EXPECT_EQ(old_third_best, windowed_max_bw_.GetBest());
}
TEST_F(WindowedFilterTest, ExpireAllMins) {
InitializeMinFilter();
QuicTime::Delta rtt_sample =
windowed_min_rtt_.GetThirdBest() + QuicTime::Delta::FromMilliseconds(5);
// This assert is necessary to avoid triggering -Wstrict-overflow
// See crbug/616957
ASSERT_LT(windowed_min_rtt_.GetThirdBest(),
QuicTime::Delta::Infinite() - QuicTime::Delta::FromMilliseconds(5));
// Third best min sample was recorded at 100ms, so expiry time is 199ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(200);
windowed_min_rtt_.Update(rtt_sample, now);
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetThirdBest());
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetSecondBest());
EXPECT_EQ(rtt_sample, windowed_min_rtt_.GetBest());
}
TEST_F(WindowedFilterTest, ExpireAllMaxs) {
InitializeMaxFilter();
QuicBandwidth bw_sample =
windowed_max_bw_.GetThirdBest() - QuicBandwidth::FromBitsPerSecond(50);
// Third best max sample was recorded at 100ms, so expiry time is 199ms.
QuicTime now = QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(200);
windowed_max_bw_.Update(bw_sample, now);
EXPECT_EQ(bw_sample, windowed_max_bw_.GetThirdBest());
EXPECT_EQ(bw_sample, windowed_max_bw_.GetSecondBest());
EXPECT_EQ(bw_sample, windowed_max_bw_.GetBest());
}
// Test the windowed filter where the time used is an exact counter instead of a
// timestamp. This is useful if, for example, the time is measured in round
// trips.
TEST_F(WindowedFilterTest, ExpireCounterBasedMax) {
// Create a window which starts at t = 0 and expires after two cycles.
WindowedFilter<uint64_t, MaxFilter<uint64_t>, uint64_t, uint64_t> max_filter(
2, 0, 0);
const uint64_t kBest = 50000;
// Insert 50000 at t = 1.
max_filter.Update(50000, 1);
EXPECT_EQ(kBest, max_filter.GetBest());
UpdateWithIrrelevantSamples(&max_filter, 20, 1);
EXPECT_EQ(kBest, max_filter.GetBest());
// Insert 40000 at t = 2. Nothing is expected to expire.
max_filter.Update(40000, 2);
EXPECT_EQ(kBest, max_filter.GetBest());
UpdateWithIrrelevantSamples(&max_filter, 20, 2);
EXPECT_EQ(kBest, max_filter.GetBest());
// Insert 30000 at t = 3. Nothing is expected to expire yet.
max_filter.Update(30000, 3);
EXPECT_EQ(kBest, max_filter.GetBest());
UpdateWithIrrelevantSamples(&max_filter, 20, 3);
EXPECT_EQ(kBest, max_filter.GetBest());
QUIC_VLOG(0) << max_filter.GetSecondBest();
QUIC_VLOG(0) << max_filter.GetThirdBest();
// Insert 20000 at t = 4. 50000 at t = 1 expires, so 40000 becomes the new
// maximum.
const uint64_t kNewBest = 40000;
max_filter.Update(20000, 4);
EXPECT_EQ(kNewBest, max_filter.GetBest());
UpdateWithIrrelevantSamples(&max_filter, 20, 4);
EXPECT_EQ(kNewBest, max_filter.GetBest());
}
} // namespace test
} // namespace quic