1 files changed, 180 insertions, 0 deletions
diff --git a/third_party/libwebrtc/net/dcsctp/tx/retransmission_timeout_test.cc b/third_party/libwebrtc/net/dcsctp/tx/retransmission_timeout_test.cc
new file mode 100644
index 0000000000..b901995e97
--- /dev/null
+++ b/third_party/libwebrtc/net/dcsctp/tx/retransmission_timeout_test.cc
@@ -0,0 +1,180 @@
+/*
+ *  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);
+constexpr DurationMs kMinRttVariance = DurationMs(220);
+
+DcSctpOptions MakeOptions() {
+  DcSctpOptions options;
+  options.rtt_max = kMaxRtt;
+  options.rto_initial = kInitialRto;
+  options.rto_max = kMaxRto;
+  options.rto_min = kMinRto;
+  options.min_rtt_variance = kMinRttVariance;
+  return options;
+}
+
+TEST(RetransmissionTimeoutTest, HasValidInitialRto) {
+  RetransmissionTimeout rto_(MakeOptions());
+  EXPECT_EQ(rto_.rto(), kInitialRto);
+}
+
+TEST(RetransmissionTimeoutTest, HasValidInitialSrtt) {
+  RetransmissionTimeout rto_(MakeOptions());
+  EXPECT_EQ(rto_.srtt(), 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(), 344);
+  rto_.ObserveRTT(DurationMs(123));
+  EXPECT_EQ(*rto_.rto(), 344);
+  rto_.ObserveRTT(DurationMs(125));
+  EXPECT_EQ(*rto_.rto(), 344);
+  rto_.ObserveRTT(DurationMs(127));
+  EXPECT_EQ(*rto_.rto(), 344);
+}
+
+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(), 710);
+  rto_.ObserveRTT(DurationMs(123));
+  EXPECT_EQ(*rto_.rto(), 631);
+  rto_.ObserveRTT(DurationMs(124));
+  EXPECT_EQ(*rto_.rto(), 562);
+  rto_.ObserveRTT(DurationMs(122));
+  EXPECT_EQ(*rto_.rto(), 505);
+  rto_.ObserveRTT(DurationMs(124));
+  EXPECT_EQ(*rto_.rto(), 454);
+  rto_.ObserveRTT(DurationMs(124));
+  EXPECT_EQ(*rto_.rto(), 410);
+  rto_.ObserveRTT(DurationMs(124));
+  EXPECT_EQ(*rto_.rto(), 372);
+  rto_.ObserveRTT(DurationMs(124));
+  EXPECT_EQ(*rto_.rto(), 367);
+}
+
+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 < 1000; ++i) {
+    rto_.ObserveRTT(DurationMs(124));
+  }
+  EXPECT_EQ(*rto_.rto(), 344);
+}
+
+TEST(RetransmissionTimeoutTest, CanSpecifySmallerMinimumRttVariance) {
+  DcSctpOptions options = MakeOptions();
+  options.min_rtt_variance = kMinRttVariance - DurationMs(100);
+  RetransmissionTimeout rto_(options);
+
+  for (int i = 0; i < 1000; ++i) {
+    rto_.ObserveRTT(DurationMs(124));
+  }
+  EXPECT_EQ(*rto_.rto(), 244);
+}
+
+TEST(RetransmissionTimeoutTest, CanSpecifyLargerMinimumRttVariance) {
+  DcSctpOptions options = MakeOptions();
+  options.min_rtt_variance = kMinRttVariance + DurationMs(100);
+  RetransmissionTimeout rto_(options);
+
+  for (int i = 0; i < 1000; ++i) {
+    rto_.ObserveRTT(DurationMs(124));
+  }
+  EXPECT_EQ(*rto_.rto(), 444);
+}
+
+}  // namespace
+}  // namespace dcsctp