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/*
* Copyright (c) 2012 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 <algorithm>
#include "rtc_base/rate_statistics.h"
#include "test/gtest.h"
namespace {
using webrtc::RateStatistics;
const int64_t kWindowMs = 500;
class RateStatisticsTest : public ::testing::Test {
protected:
RateStatisticsTest() : stats_(kWindowMs, 8000) {}
RateStatistics stats_;
};
TEST_F(RateStatisticsTest, TestStrictMode) {
int64_t now_ms = 0;
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
const uint32_t kPacketSize = 1500u;
const uint32_t kExpectedRateBps = kPacketSize * 1000 * 8;
// Single data point is not enough for valid estimate.
stats_.Update(kPacketSize, now_ms++);
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
// Expecting 1200 kbps since the window is initially kept small and grows as
// we have more data.
stats_.Update(kPacketSize, now_ms);
EXPECT_EQ(kExpectedRateBps, *stats_.Rate(now_ms));
stats_.Reset();
// Expecting 0 after init.
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
const int kInterval = 10;
for (int i = 0; i < 100000; ++i) {
if (i % kInterval == 0)
stats_.Update(kPacketSize, now_ms);
// Approximately 1200 kbps expected. Not exact since when packets
// are removed we will jump 10 ms to the next packet.
if (i > kInterval) {
absl::optional<uint32_t> rate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(rate));
uint32_t samples = i / kInterval + 1;
uint64_t total_bits = samples * kPacketSize * 8;
uint32_t rate_bps = static_cast<uint32_t>((1000 * total_bits) / (i + 1));
EXPECT_NEAR(rate_bps, *rate, 22000u);
}
now_ms += 1;
}
now_ms += kWindowMs;
// The window is 2 seconds. If nothing has been received for that time
// the estimate should be 0.
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
}
TEST_F(RateStatisticsTest, IncreasingThenDecreasingBitrate) {
int64_t now_ms = 0;
stats_.Reset();
// Expecting 0 after init.
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
stats_.Update(1000, ++now_ms);
const uint32_t kExpectedBitrate = 8000000;
// 1000 bytes per millisecond until plateau is reached.
int prev_error = kExpectedBitrate;
absl::optional<uint32_t> bitrate;
while (++now_ms < 10000) {
stats_.Update(1000, now_ms);
bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
int error = kExpectedBitrate - *bitrate;
error = std::abs(error);
// Expect the estimation error to decrease as the window is extended.
EXPECT_LE(error, prev_error + 1);
prev_error = error;
}
// Window filled, expect to be close to 8000000.
EXPECT_EQ(kExpectedBitrate, *bitrate);
// 1000 bytes per millisecond until 10-second mark, 8000 kbps expected.
while (++now_ms < 10000) {
stats_.Update(1000, now_ms);
bitrate = stats_.Rate(now_ms);
EXPECT_EQ(kExpectedBitrate, *bitrate);
}
// Zero bytes per millisecond until 0 is reached.
while (++now_ms < 20000) {
stats_.Update(0, now_ms);
absl::optional<uint32_t> new_bitrate = stats_.Rate(now_ms);
if (static_cast<bool>(new_bitrate) && *new_bitrate != *bitrate) {
// New bitrate must be lower than previous one.
EXPECT_LT(*new_bitrate, *bitrate);
} else {
// 0 kbps expected.
EXPECT_EQ(0u, *new_bitrate);
break;
}
bitrate = new_bitrate;
}
// Zero bytes per millisecond until 20-second mark, 0 kbps expected.
while (++now_ms < 20000) {
stats_.Update(0, now_ms);
EXPECT_EQ(0u, *stats_.Rate(now_ms));
}
}
TEST_F(RateStatisticsTest, ResetAfterSilence) {
int64_t now_ms = 0;
stats_.Reset();
// Expecting 0 after init.
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
const uint32_t kExpectedBitrate = 8000000;
// 1000 bytes per millisecond until the window has been filled.
int prev_error = kExpectedBitrate;
absl::optional<uint32_t> bitrate;
while (++now_ms < 10000) {
stats_.Update(1000, now_ms);
bitrate = stats_.Rate(now_ms);
if (bitrate) {
int error = kExpectedBitrate - *bitrate;
error = std::abs(error);
// Expect the estimation error to decrease as the window is extended.
EXPECT_LE(error, prev_error + 1);
prev_error = error;
}
}
// Window filled, expect to be close to 8000000.
EXPECT_EQ(kExpectedBitrate, *bitrate);
now_ms += kWindowMs + 1;
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
stats_.Update(1000, now_ms);
++now_ms;
stats_.Update(1000, now_ms);
// We expect two samples of 1000 bytes, and that the bitrate is measured over
// 500 ms, i.e. 2 * 8 * 1000 / 0.500 = 32000.
EXPECT_EQ(32000u, *stats_.Rate(now_ms));
// Reset, add the same samples again.
stats_.Reset();
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
stats_.Update(1000, now_ms);
++now_ms;
stats_.Update(1000, now_ms);
// We expect two samples of 1000 bytes, and that the bitrate is measured over
// 2 ms (window size has been reset) i.e. 2 * 8 * 1000 / 0.002 = 8000000.
EXPECT_EQ(kExpectedBitrate, *stats_.Rate(now_ms));
}
TEST_F(RateStatisticsTest, HandlesChangingWindowSize) {
int64_t now_ms = 0;
stats_.Reset();
// Sanity test window size.
EXPECT_TRUE(stats_.SetWindowSize(kWindowMs, now_ms));
EXPECT_FALSE(stats_.SetWindowSize(kWindowMs + 1, now_ms));
EXPECT_FALSE(stats_.SetWindowSize(0, now_ms));
EXPECT_TRUE(stats_.SetWindowSize(1, now_ms));
EXPECT_TRUE(stats_.SetWindowSize(kWindowMs, now_ms));
// Fill the buffer at a rate of 1 byte / millisecond (8 kbps).
const int kBatchSize = 10;
for (int i = 0; i <= kWindowMs; i += kBatchSize)
stats_.Update(kBatchSize, now_ms += kBatchSize);
EXPECT_EQ(static_cast<uint32_t>(8000), *stats_.Rate(now_ms));
// Halve the window size, rate should stay the same.
EXPECT_TRUE(stats_.SetWindowSize(kWindowMs / 2, now_ms));
EXPECT_EQ(static_cast<uint32_t>(8000), *stats_.Rate(now_ms));
// Double the window size again, rate should stay the same. (As the window
// won't actually expand until new bit and bobs fall into it.
EXPECT_TRUE(stats_.SetWindowSize(kWindowMs, now_ms));
EXPECT_EQ(static_cast<uint32_t>(8000), *stats_.Rate(now_ms));
// Fill the now empty half with bits it twice the rate.
for (int i = 0; i < kWindowMs / 2; i += kBatchSize)
stats_.Update(kBatchSize * 2, now_ms += kBatchSize);
// Rate should have increase be 50%.
EXPECT_EQ(static_cast<uint32_t>((8000 * 3) / 2), *stats_.Rate(now_ms));
}
TEST_F(RateStatisticsTest, RespectsWindowSizeEdges) {
int64_t now_ms = 0;
stats_.Reset();
// Expecting 0 after init.
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
// One byte per ms, using one big sample.
stats_.Update(kWindowMs, now_ms);
now_ms += kWindowMs - 2;
// Shouldn't work! (Only one sample, not full window size.)
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
// Window size should be full, and the single data point should be accepted.
++now_ms;
absl::optional<uint32_t> bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
EXPECT_EQ(1000 * 8u, *bitrate);
// Add another, now we have twice the bitrate.
stats_.Update(kWindowMs, now_ms);
bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
EXPECT_EQ(2 * 1000 * 8u, *bitrate);
// Now that first sample should drop out...
now_ms += 1;
bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
EXPECT_EQ(1000 * 8u, *bitrate);
}
TEST_F(RateStatisticsTest, HandlesZeroCounts) {
int64_t now_ms = 0;
stats_.Reset();
// Expecting 0 after init.
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
stats_.Update(kWindowMs, now_ms);
now_ms += kWindowMs - 1;
stats_.Update(0, now_ms);
absl::optional<uint32_t> bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
EXPECT_EQ(1000 * 8u, *bitrate);
// Move window along so first data point falls out.
++now_ms;
bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
EXPECT_EQ(0u, *bitrate);
// Move window so last data point falls out.
now_ms += kWindowMs;
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
}
TEST_F(RateStatisticsTest, HandlesQuietPeriods) {
int64_t now_ms = 0;
stats_.Reset();
// Expecting 0 after init.
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
stats_.Update(0, now_ms);
now_ms += kWindowMs - 1;
absl::optional<uint32_t> bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
EXPECT_EQ(0u, *bitrate);
// Move window along so first data point falls out.
++now_ms;
EXPECT_FALSE(static_cast<bool>(stats_.Rate(now_ms)));
// Move window a long way out.
now_ms += 2 * kWindowMs;
stats_.Update(0, now_ms);
bitrate = stats_.Rate(now_ms);
EXPECT_TRUE(static_cast<bool>(bitrate));
EXPECT_EQ(0u, *bitrate);
}
} // namespace