Let alr dectector use a budged to detect underuse.

webrtc/modules/pacing/interval_budget_unittest.cc

Index: webrtc/modules/pacing/interval_budget_unittest.cc
diff --git a/webrtc/modules/pacing/interval_budget_unittest.cc b/webrtc/modules/pacing/interval_budget_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fe6065dac8658676bb7b5c3346b24829e63cfb93
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+++ b/webrtc/modules/pacing/interval_budget_unittest.cc
@@ -0,0 +1,119 @@
+/*
+ *  Copyright (c) 2016 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 "webrtc/modules/pacing/interval_budget.h"
+
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+
+namespace {
+constexpr int kWindowMs = 500;
+constexpr int kBitrateKbps = 100;
+constexpr bool kCanBuildUpUnderuse = true;
+constexpr bool kCanNotBuildUpUnderuse = false;
+size_t TimeToBytes(int bitrate_kbps, int time_ms) {
+  return static_cast<size_t>(bitrate_kbps * time_ms / 8);
+}
+}
+
+TEST(IntervalBudgetTest, InitailState) {
+  IntervalBudget interval_budget(kBitrateKbps);
+  EXPECT_EQ(interval_budget.budget_level_percent(), 0);
+  EXPECT_EQ(interval_budget.bytes_remaining(), 0u);
+}
+
+TEST(IntervalBudgetTest, Underuse) {
+  IntervalBudget interval_budget(kBitrateKbps);
+  int delta_time_ms = 50;
+  interval_budget.IncreaseBudget(delta_time_ms);
+  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps, delta_time_ms));
+}
+
+TEST(IntervalBudgetTest, DontUnderuseMoreThanMaxWindow) {
+  IntervalBudget interval_budget(kBitrateKbps);
+  int delta_time_ms = 1000;
+  interval_budget.IncreaseBudget(delta_time_ms);
+  EXPECT_EQ(interval_budget.budget_level_percent(), 100);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps, kWindowMs));
+}
+
+TEST(IntervalBudgetTest, DontUnderuseMoreThanMaxWindowWhenChangeBitrate) {
+  IntervalBudget interval_budget(kBitrateKbps);
+  int delta_time_ms = kWindowMs / 2;
+  interval_budget.IncreaseBudget(delta_time_ms);
+  interval_budget.set_target_rate_kbps(kBitrateKbps / 10);
+  EXPECT_EQ(interval_budget.budget_level_percent(), 100);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps / 10, kWindowMs));
+}
+
+TEST(IntervalBudgetTest, BalanceChangeOnBitrateChange) {
+  IntervalBudget interval_budget(kBitrateKbps);
+  int delta_time_ms = kWindowMs;
+  interval_budget.IncreaseBudget(delta_time_ms);
+  interval_budget.set_target_rate_kbps(kBitrateKbps * 2);
+  EXPECT_EQ(interval_budget.budget_level_percent(), 50);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps, kWindowMs));
+}
+
+TEST(IntervalBudgetTest, Overuse) {
+  IntervalBudget interval_budget(kBitrateKbps);
+  int overuse_time_ms = 50;
+  int used_bytes = TimeToBytes(kBitrateKbps, overuse_time_ms);
+  interval_budget.UseBudget(used_bytes);
+  EXPECT_EQ(interval_budget.budget_level_percent(),
+            -kWindowMs / overuse_time_ms);
+  EXPECT_EQ(interval_budget.bytes_remaining(), 0u);
+}
+
+TEST(IntervalBudgetTest, DontOveruseMoreThanMaxWindow) {
+  IntervalBudget interval_budget(kBitrateKbps);
+  int overuse_time_ms = 1000;
+  int used_bytes = TimeToBytes(kBitrateKbps, overuse_time_ms);
+  interval_budget.UseBudget(used_bytes);
+  EXPECT_EQ(interval_budget.budget_level_percent(), -100);
+  EXPECT_EQ(interval_budget.bytes_remaining(), 0u);
+}
+
+TEST(IntervalBudgetTest, CanBuildUpUnderuseWhenConfigured) {
+  IntervalBudget interval_budget(kBitrateKbps, kCanBuildUpUnderuse);
+  int delta_time_ms = 50;
+  interval_budget.IncreaseBudget(delta_time_ms);
+  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps, delta_time_ms));
+
+  interval_budget.IncreaseBudget(delta_time_ms);
+  EXPECT_EQ(interval_budget.budget_level_percent(),
+            2 * kWindowMs / delta_time_ms);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps, 2 * delta_time_ms));
+}
+
+TEST(IntervalBudgetTest, CanNotBuildUpUnderuseWhenConfigured) {
+  IntervalBudget interval_budget(kBitrateKbps, kCanNotBuildUpUnderuse);
+  int delta_time_ms = 50;
+  interval_budget.IncreaseBudget(delta_time_ms);
+  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps, delta_time_ms));
+
+  interval_budget.IncreaseBudget(delta_time_ms);
+  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_EQ(interval_budget.bytes_remaining(),
+            TimeToBytes(kBitrateKbps, delta_time_ms));
+}
+
+}  // namespace webrtc