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/*
* Copyright (c) 2021 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 "net/dcsctp/tx/retransmission_timeout.h"
#include "net/dcsctp/public/dcsctp_options.h"
#include "rtc_base/gunit.h"
#include "test/gmock.h"
namespace dcsctp {
namespace {
constexpr DurationMs kMaxRtt = DurationMs(8'000);
constexpr DurationMs kInitialRto = DurationMs(200);
constexpr DurationMs kMaxRto = DurationMs(800);
constexpr DurationMs kMinRto = DurationMs(120);
DcSctpOptions MakeOptions() {
DcSctpOptions options;
options.rtt_max = kMaxRtt;
options.rto_initial = kInitialRto;
options.rto_max = kMaxRto;
options.rto_min = kMinRto;
return options;
}
TEST(RetransmissionTimeoutTest, HasValidInitialRto) {
RetransmissionTimeout rto_(MakeOptions());
EXPECT_EQ(rto_.rto(), kInitialRto);
}
TEST(RetransmissionTimeoutTest, NegativeValuesDoNotAffectRTO) {
RetransmissionTimeout rto_(MakeOptions());
// Initial negative value
rto_.ObserveRTT(DurationMs(-10));
EXPECT_EQ(rto_.rto(), kInitialRto);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 372);
// Subsequent negative value
rto_.ObserveRTT(DurationMs(-10));
EXPECT_EQ(*rto_.rto(), 372);
}
TEST(RetransmissionTimeoutTest, TooLargeValuesDoNotAffectRTO) {
RetransmissionTimeout rto_(MakeOptions());
// Initial too large value
rto_.ObserveRTT(kMaxRtt + DurationMs(100));
EXPECT_EQ(rto_.rto(), kInitialRto);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 372);
// Subsequent too large value
rto_.ObserveRTT(kMaxRtt + DurationMs(100));
EXPECT_EQ(*rto_.rto(), 372);
}
TEST(RetransmissionTimeoutTest, WillNeverGoBelowMinimumRto) {
RetransmissionTimeout rto_(MakeOptions());
for (int i = 0; i < 1000; ++i) {
rto_.ObserveRTT(DurationMs(1));
}
EXPECT_GE(rto_.rto(), kMinRto);
}
TEST(RetransmissionTimeoutTest, WillNeverGoAboveMaximumRto) {
RetransmissionTimeout rto_(MakeOptions());
for (int i = 0; i < 1000; ++i) {
rto_.ObserveRTT(kMaxRtt - DurationMs(1));
// Adding jitter, which would make it RTO be well above RTT.
rto_.ObserveRTT(kMaxRtt - DurationMs(100));
}
EXPECT_LE(rto_.rto(), kMaxRto);
}
TEST(RetransmissionTimeoutTest, CalculatesRtoForStableRtt) {
RetransmissionTimeout rto_(MakeOptions());
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 372);
rto_.ObserveRTT(DurationMs(128));
EXPECT_EQ(*rto_.rto(), 314);
rto_.ObserveRTT(DurationMs(123));
EXPECT_EQ(*rto_.rto(), 268);
rto_.ObserveRTT(DurationMs(125));
EXPECT_EQ(*rto_.rto(), 233);
rto_.ObserveRTT(DurationMs(127));
EXPECT_EQ(*rto_.rto(), 208);
}
TEST(RetransmissionTimeoutTest, CalculatesRtoForUnstableRtt) {
RetransmissionTimeout rto_(MakeOptions());
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 372);
rto_.ObserveRTT(DurationMs(402));
EXPECT_EQ(*rto_.rto(), 622);
rto_.ObserveRTT(DurationMs(728));
EXPECT_EQ(*rto_.rto(), 800);
rto_.ObserveRTT(DurationMs(89));
EXPECT_EQ(*rto_.rto(), 800);
rto_.ObserveRTT(DurationMs(126));
EXPECT_EQ(*rto_.rto(), 800);
}
TEST(RetransmissionTimeoutTest, WillStabilizeAfterAWhile) {
RetransmissionTimeout rto_(MakeOptions());
rto_.ObserveRTT(DurationMs(124));
rto_.ObserveRTT(DurationMs(402));
rto_.ObserveRTT(DurationMs(728));
rto_.ObserveRTT(DurationMs(89));
rto_.ObserveRTT(DurationMs(126));
EXPECT_EQ(*rto_.rto(), 800);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 800);
rto_.ObserveRTT(DurationMs(122));
EXPECT_EQ(*rto_.rto(), 709);
rto_.ObserveRTT(DurationMs(123));
EXPECT_EQ(*rto_.rto(), 630);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 561);
rto_.ObserveRTT(DurationMs(122));
EXPECT_EQ(*rto_.rto(), 504);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 453);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 409);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 372);
rto_.ObserveRTT(DurationMs(124));
EXPECT_EQ(*rto_.rto(), 339);
}
TEST(RetransmissionTimeoutTest, WillAlwaysStayAboveRTT) {
// In simulations, it's quite common to have a very stable RTT, and having an
// RTO at the same value will cause issues as expiry timers will be scheduled
// to be expire exactly when a packet is supposed to arrive. The RTO must be
// larger than the RTT. In non-simulated environments, this is a non-issue as
// any jitter will increase the RTO.
RetransmissionTimeout rto_(MakeOptions());
for (int i = 0; i < 100; ++i) {
rto_.ObserveRTT(DurationMs(124));
}
EXPECT_GT(*rto_.rto(), 124);
}
} // namespace
} // namespace dcsctp
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