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// Copyright 2013 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 "base/test/simple_test_tick_clock.h"
#include "media/cast/cast_defines.h"
#include "media/cast/congestion_control/congestion_control.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace media {
namespace cast {
static const uint32 kMaxBitrateConfigured = 5000000;
static const uint32 kMinBitrateConfigured = 500000;
static const uint32 kStartBitrate = 2000000;
static const int64 kStartMillisecond = GG_INT64_C(12345678900000);
static const int64 kRttMs = 20;
static const int64 kAckRateMs = 33;
class CongestionControlTest : public ::testing::Test {
protected:
CongestionControlTest()
: congestion_control_(&testing_clock_,
kDefaultCongestionControlBackOff,
kMaxBitrateConfigured,
kMinBitrateConfigured,
kStartBitrate) {
testing_clock_.Advance(
base::TimeDelta::FromMilliseconds(kStartMillisecond));
}
// Returns the last bitrate of the run.
uint32 RunWithOneLossEventPerSecond(int fps, int rtt_ms,
int runtime_in_seconds) {
const base::TimeDelta rtt = base::TimeDelta::FromMilliseconds(rtt_ms);
const base::TimeDelta ack_rate =
base::TimeDelta::FromMilliseconds(GG_INT64_C(1000) / fps);
uint32 new_bitrate = 0;
EXPECT_FALSE(congestion_control_.OnAck(rtt, &new_bitrate));
for (int seconds = 0; seconds < runtime_in_seconds; ++seconds) {
for (int i = 1; i < fps; ++i) {
testing_clock_.Advance(ack_rate);
congestion_control_.OnAck(rtt, &new_bitrate);
}
EXPECT_TRUE(congestion_control_.OnNack(rtt, &new_bitrate));
}
return new_bitrate;
}
base::SimpleTestTickClock testing_clock_;
CongestionControl congestion_control_;
};
TEST_F(CongestionControlTest, Max) {
uint32 new_bitrate = 0;
const base::TimeDelta rtt = base::TimeDelta::FromMilliseconds(kRttMs);
const base::TimeDelta ack_rate =
base::TimeDelta::FromMilliseconds(kAckRateMs);
EXPECT_FALSE(congestion_control_.OnAck(rtt, &new_bitrate));
uint32 expected_increase_bitrate = 0;
// Expected time is 5 seconds. 500000 - 2000000 = 5 * 1500 * 8 * (1000 / 20).
for (int i = 0; i < 151; ++i) {
testing_clock_.Advance(ack_rate);
EXPECT_TRUE(congestion_control_.OnAck(rtt, &new_bitrate));
expected_increase_bitrate += 1500 * 8 * kAckRateMs / kRttMs;
EXPECT_EQ(kStartBitrate + expected_increase_bitrate, new_bitrate);
}
testing_clock_.Advance(ack_rate);
EXPECT_TRUE(congestion_control_.OnAck(rtt, &new_bitrate));
EXPECT_EQ(kMaxBitrateConfigured, new_bitrate);
}
TEST_F(CongestionControlTest, Min) {
uint32 new_bitrate = 0;
const base::TimeDelta rtt = base::TimeDelta::FromMilliseconds(kRttMs);
const base::TimeDelta ack_rate =
base::TimeDelta::FromMilliseconds(kAckRateMs);
EXPECT_FALSE(congestion_control_.OnNack(rtt, &new_bitrate));
uint32 expected_decrease_bitrate = kStartBitrate;
// Expected number is 10. 2000 * 0.875^10 <= 500.
for (int i = 0; i < 10; ++i) {
testing_clock_.Advance(ack_rate);
EXPECT_TRUE(congestion_control_.OnNack(rtt, &new_bitrate));
expected_decrease_bitrate = static_cast<uint32>(
expected_decrease_bitrate * kDefaultCongestionControlBackOff);
EXPECT_EQ(expected_decrease_bitrate, new_bitrate);
}
testing_clock_.Advance(ack_rate);
EXPECT_TRUE(congestion_control_.OnNack(rtt, &new_bitrate));
EXPECT_EQ(kMinBitrateConfigured, new_bitrate);
}
TEST_F(CongestionControlTest, Timing) {
const base::TimeDelta rtt = base::TimeDelta::FromMilliseconds(kRttMs);
const base::TimeDelta ack_rate =
base::TimeDelta::FromMilliseconds(kAckRateMs);
uint32 new_bitrate = 0;
uint32 expected_bitrate = kStartBitrate;
EXPECT_FALSE(congestion_control_.OnAck(rtt, &new_bitrate));
testing_clock_.Advance(ack_rate);
EXPECT_TRUE(congestion_control_.OnAck(rtt, &new_bitrate));
expected_bitrate += 1500 * 8 * kAckRateMs / kRttMs;
EXPECT_EQ(expected_bitrate, new_bitrate);
// We should back immediately.
EXPECT_TRUE(congestion_control_.OnNack(rtt, &new_bitrate));
expected_bitrate = static_cast<uint32>(
expected_bitrate * kDefaultCongestionControlBackOff);
EXPECT_EQ(expected_bitrate, new_bitrate);
// Less than one RTT have passed don't back again.
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(10));
EXPECT_FALSE(congestion_control_.OnNack(rtt, &new_bitrate));
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(10));
EXPECT_TRUE(congestion_control_.OnNack(rtt, &new_bitrate));
expected_bitrate = static_cast<uint32>(
expected_bitrate * kDefaultCongestionControlBackOff);
EXPECT_EQ(expected_bitrate, new_bitrate);
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(10));
EXPECT_FALSE(congestion_control_.OnAck(rtt, &new_bitrate));
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(10));
EXPECT_TRUE(congestion_control_.OnAck(rtt, &new_bitrate));
expected_bitrate += 1500 * 8 * 20 / kRttMs;
EXPECT_EQ(expected_bitrate, new_bitrate);
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(10));
EXPECT_FALSE(congestion_control_.OnAck(rtt, &new_bitrate));
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(10));
EXPECT_TRUE(congestion_control_.OnAck(rtt, &new_bitrate));
expected_bitrate += 1500 * 8 * 20 / kRttMs;
EXPECT_EQ(expected_bitrate, new_bitrate);
// Test long elapsed time (300 ms).
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(300));
EXPECT_TRUE(congestion_control_.OnAck(rtt, &new_bitrate));
expected_bitrate += 1500 * 8 * 100 / kRttMs;
EXPECT_EQ(expected_bitrate, new_bitrate);
// Test many short elapsed time (1 ms).
for (int i = 0; i < 19; ++i) {
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(1));
EXPECT_FALSE(congestion_control_.OnAck(rtt, &new_bitrate));
}
testing_clock_.Advance(base::TimeDelta::FromMilliseconds(1));
EXPECT_TRUE(congestion_control_.OnAck(rtt, &new_bitrate));
expected_bitrate += 1500 * 8 * 20 / kRttMs;
EXPECT_EQ(expected_bitrate, new_bitrate);
}
TEST_F(CongestionControlTest, Convergence24fps) {
EXPECT_GE(RunWithOneLossEventPerSecond(24, kRttMs, 100),
GG_UINT32_C(3000000));
}
TEST_F(CongestionControlTest, Convergence24fpsLongRtt) {
EXPECT_GE(RunWithOneLossEventPerSecond(24, 100, 100),
GG_UINT32_C(500000));
}
TEST_F(CongestionControlTest, Convergence60fps) {
EXPECT_GE(RunWithOneLossEventPerSecond(60, kRttMs, 100),
GG_UINT32_C(3500000));
}
TEST_F(CongestionControlTest, Convergence60fpsLongRtt) {
EXPECT_GE(RunWithOneLossEventPerSecond(60, 100, 100),
GG_UINT32_C(500000));
}
} // namespace cast
} // namespace media
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