blob: bdf54c611fcc96a95140f424de56db17cf42869c [file] [log] [blame]
// Copyright 2014 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/rtt_stats.h"
#include <cmath>
#include "quic/platform/api/quic_logging.h"
#include "quic/platform/api/quic_mock_log.h"
#include "quic/platform/api/quic_test.h"
#include "quic/test_tools/quic_test_utils.h"
#include "quic/test_tools/rtt_stats_peer.h"
using testing::_;
using testing::Message;
namespace quic {
namespace test {
class RttStatsTest : public QuicTest {
protected:
RttStats rtt_stats_;
};
TEST_F(RttStatsTest, DefaultsBeforeUpdate) {
EXPECT_LT(QuicTime::Delta::Zero(), rtt_stats_.initial_rtt());
EXPECT_EQ(QuicTime::Delta::Zero(), rtt_stats_.min_rtt());
EXPECT_EQ(QuicTime::Delta::Zero(), rtt_stats_.smoothed_rtt());
}
TEST_F(RttStatsTest, SmoothedRtt) {
// Verify that ack_delay is ignored in the first measurement.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(300),
QuicTime::Delta::FromMilliseconds(100),
QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.smoothed_rtt());
// Verify that a plausible ack delay increases the max ack delay.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(400),
QuicTime::Delta::FromMilliseconds(100),
QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.smoothed_rtt());
// Verify that Smoothed RTT includes max ack delay if it's reasonable.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(350),
QuicTime::Delta::FromMilliseconds(50), QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.smoothed_rtt());
// Verify that large erroneous ack_delay does not change Smoothed RTT.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(200),
QuicTime::Delta::FromMilliseconds(300),
QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMicroseconds(287500),
rtt_stats_.smoothed_rtt());
}
TEST_F(RttStatsTest, SmoothedRttIgnoreAckDelay) {
rtt_stats_.set_ignore_max_ack_delay(true);
// Verify that ack_delay is ignored in the first measurement.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(300),
QuicTime::Delta::FromMilliseconds(100),
QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.smoothed_rtt());
// Verify that a plausible ack delay increases the max ack delay.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(300),
QuicTime::Delta::FromMilliseconds(100),
QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.smoothed_rtt());
// Verify that Smoothed RTT includes max ack delay if it's reasonable.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(300),
QuicTime::Delta::FromMilliseconds(50), QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(300), rtt_stats_.smoothed_rtt());
// Verify that large erroneous ack_delay does not change Smoothed RTT.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(200),
QuicTime::Delta::FromMilliseconds(300),
QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMicroseconds(287500),
rtt_stats_.smoothed_rtt());
}
// Ensure that the potential rounding artifacts in EWMA calculation do not cause
// the SRTT to drift too far from the exact value.
TEST_F(RttStatsTest, SmoothedRttStability) {
for (size_t time = 3; time < 20000; time++) {
RttStats stats;
for (size_t i = 0; i < 100; i++) {
stats.UpdateRtt(QuicTime::Delta::FromMicroseconds(time),
QuicTime::Delta::FromMilliseconds(0), QuicTime::Zero());
int64_t time_delta_us = stats.smoothed_rtt().ToMicroseconds() - time;
ASSERT_LE(std::abs(time_delta_us), 1);
}
}
}
TEST_F(RttStatsTest, PreviousSmoothedRtt) {
// Verify that ack_delay is corrected for in Smoothed RTT.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(200),
QuicTime::Delta::FromMilliseconds(0), QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.smoothed_rtt());
EXPECT_EQ(QuicTime::Delta::Zero(), rtt_stats_.previous_srtt());
// Ensure the previous SRTT is 200ms after a 100ms sample.
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(100),
QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(100), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMicroseconds(187500).ToMicroseconds(),
rtt_stats_.smoothed_rtt().ToMicroseconds());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.previous_srtt());
}
TEST_F(RttStatsTest, MinRtt) {
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(200),
QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.min_rtt());
rtt_stats_.UpdateRtt(
QuicTime::Delta::FromMilliseconds(10), QuicTime::Delta::Zero(),
QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(10));
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
rtt_stats_.UpdateRtt(
QuicTime::Delta::FromMilliseconds(50), QuicTime::Delta::Zero(),
QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(20));
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
rtt_stats_.UpdateRtt(
QuicTime::Delta::FromMilliseconds(50), QuicTime::Delta::Zero(),
QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(30));
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
rtt_stats_.UpdateRtt(
QuicTime::Delta::FromMilliseconds(50), QuicTime::Delta::Zero(),
QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(40));
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
// Verify that ack_delay does not go into recording of min_rtt_.
rtt_stats_.UpdateRtt(
QuicTime::Delta::FromMilliseconds(7),
QuicTime::Delta::FromMilliseconds(2),
QuicTime::Zero() + QuicTime::Delta::FromMilliseconds(50));
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(7), rtt_stats_.min_rtt());
}
TEST_F(RttStatsTest, ExpireSmoothedMetrics) {
QuicTime::Delta initial_rtt = QuicTime::Delta::FromMilliseconds(10);
rtt_stats_.UpdateRtt(initial_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_EQ(initial_rtt, rtt_stats_.min_rtt());
EXPECT_EQ(initial_rtt, rtt_stats_.smoothed_rtt());
EXPECT_EQ(0.5 * initial_rtt, rtt_stats_.mean_deviation());
// Update once with a 20ms RTT.
QuicTime::Delta doubled_rtt = 2 * initial_rtt;
rtt_stats_.UpdateRtt(doubled_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_EQ(1.125 * initial_rtt, rtt_stats_.smoothed_rtt());
// Expire the smoothed metrics, increasing smoothed rtt and mean deviation.
rtt_stats_.ExpireSmoothedMetrics();
EXPECT_EQ(doubled_rtt, rtt_stats_.smoothed_rtt());
EXPECT_EQ(0.875 * initial_rtt, rtt_stats_.mean_deviation());
// Now go back down to 5ms and expire the smoothed metrics, and ensure the
// mean deviation increases to 15ms.
QuicTime::Delta half_rtt = 0.5 * initial_rtt;
rtt_stats_.UpdateRtt(half_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_GT(doubled_rtt, rtt_stats_.smoothed_rtt());
EXPECT_LT(initial_rtt, rtt_stats_.mean_deviation());
}
TEST_F(RttStatsTest, UpdateRttWithBadSendDeltas) {
// Make sure we ignore bad RTTs.
CREATE_QUIC_MOCK_LOG(log);
QuicTime::Delta initial_rtt = QuicTime::Delta::FromMilliseconds(10);
rtt_stats_.UpdateRtt(initial_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_EQ(initial_rtt, rtt_stats_.min_rtt());
EXPECT_EQ(initial_rtt, rtt_stats_.smoothed_rtt());
std::vector<QuicTime::Delta> bad_send_deltas;
bad_send_deltas.push_back(QuicTime::Delta::Zero());
bad_send_deltas.push_back(QuicTime::Delta::Infinite());
bad_send_deltas.push_back(QuicTime::Delta::FromMicroseconds(-1000));
log.StartCapturingLogs();
for (QuicTime::Delta bad_send_delta : bad_send_deltas) {
SCOPED_TRACE(Message() << "bad_send_delta = "
<< bad_send_delta.ToMicroseconds());
if (QUIC_LOG_WARNING_IS_ON()) {
EXPECT_QUIC_LOG_CALL_CONTAINS(log, WARNING, "Ignoring");
}
rtt_stats_.UpdateRtt(bad_send_delta, QuicTime::Delta::Zero(),
QuicTime::Zero());
EXPECT_EQ(initial_rtt, rtt_stats_.min_rtt());
EXPECT_EQ(initial_rtt, rtt_stats_.smoothed_rtt());
}
}
TEST_F(RttStatsTest, ResetAfterConnectionMigrations) {
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(200),
QuicTime::Delta::FromMilliseconds(0), QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.smoothed_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.min_rtt());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(300),
QuicTime::Delta::FromMilliseconds(100),
QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.smoothed_rtt());
EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.min_rtt());
// Reset rtt stats on connection migrations.
rtt_stats_.OnConnectionMigration();
EXPECT_EQ(QuicTime::Delta::Zero(), rtt_stats_.latest_rtt());
EXPECT_EQ(QuicTime::Delta::Zero(), rtt_stats_.smoothed_rtt());
EXPECT_EQ(QuicTime::Delta::Zero(), rtt_stats_.min_rtt());
}
TEST_F(RttStatsTest, StandardDeviationCaculatorTest1) {
// All samples are the same.
rtt_stats_.EnableStandardDeviationCalculation();
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_EQ(rtt_stats_.mean_deviation(),
rtt_stats_.GetStandardOrMeanDeviation());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_EQ(QuicTime::Delta::Zero(), rtt_stats_.GetStandardOrMeanDeviation());
}
TEST_F(RttStatsTest, StandardDeviationCaculatorTest2) {
// Small variance.
rtt_stats_.EnableStandardDeviationCalculation();
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(9),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(11),
QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_LT(QuicTime::Delta::FromMicroseconds(500),
rtt_stats_.GetStandardOrMeanDeviation());
EXPECT_GT(QuicTime::Delta::FromMilliseconds(1),
rtt_stats_.GetStandardOrMeanDeviation());
}
TEST_F(RttStatsTest, StandardDeviationCaculatorTest3) {
// Some variance.
rtt_stats_.EnableStandardDeviationCalculation();
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(100),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(100),
QuicTime::Delta::Zero(), QuicTime::Zero());
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
QuicTime::Delta::Zero(), QuicTime::Zero());
EXPECT_APPROX_EQ(rtt_stats_.mean_deviation(),
rtt_stats_.GetStandardOrMeanDeviation(), 0.25f);
}
} // namespace test
} // namespace quic