Add a rate tracker that tracks rate over a given interval split up into buckets that accumulate uni…

webrtc/base/bucketratetracker_unittest.cc

+/*
+ *  Copyright 2015 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/base/gunit.h"
+#include "webrtc/base/bucketratetracker.h"
+
+namespace rtc {
+
+class BucketRateTrackerForTest : public BucketRateTracker {
+ public:
+  BucketRateTrackerForTest() : BucketRateTracker(100u, 10u), time_(0) {}
+  virtual uint32 Time() const { return time_; }
+  void AdvanceTime(uint32 delta) { time_ += delta; }
+
+ private:
+  uint32 time_;
+};
+
+TEST(BucketRateTrackerTest, Test30FPS) {
+  BucketRateTrackerForTest tracker;
+
+  for (int i = 0; i < 300; ++i) {
+    tracker.AddSamples(1);
+    tracker.AdvanceTime(33);
+    if (i % 3 == 0) {
+      tracker.AdvanceTime(1);
+    }
+  }
+  EXPECT_EQ(30u, tracker.ComputeCurrentRate(50000u));
+}
+
+TEST(BucketRateTrackerTest, Test60FPS) {
+  BucketRateTrackerForTest tracker;
+
+  for (int i = 0; i < 300; ++i) {
+    tracker.AddSamples(1);
+    tracker.AdvanceTime(16);
+    if (i % 3 != 0) {
+      tracker.AdvanceTime(1);
+    }
+  }
+  EXPECT_EQ(60u, tracker.ComputeCurrentRate(1000u));
+}
+
+TEST(BucketRateTrackerTest, TestRateTrackerBasics) {
+  BucketRateTrackerForTest tracker;
+  EXPECT_EQ(0U, tracker.ComputeCurrentRate(1000u));
+
+  // Add a sample.
+  tracker.AddSamples(1234);
+  // Advance the clock by 100 ms.
+  tracker.AdvanceTime(100);
+  EXPECT_EQ(12340U, tracker.ComputeCurrentRate(1000u));
+
+  // Repeat.
+  tracker.AddSamples(1234);
+  tracker.AdvanceTime(100);
+  EXPECT_EQ(12340U, tracker.ComputeCurrentRate(1000u));
+
+  // Advance the clock by 800 ms, so we've elapsed a full second.
+  // units_second should now be filled in properly.
+  tracker.AdvanceTime(800);
+  EXPECT_EQ(1234U * 2, tracker.ComputeCurrentRate(1000u));
+
+  // Poll the tracker again immediately. The reported rate should stay the same.
+  EXPECT_EQ(1234U * 2, tracker.ComputeCurrentRate(1000u));
+
+  // Do nothing and advance by a second. We should drop down to zero.
+  tracker.AdvanceTime(1000);
+  EXPECT_EQ(0U, tracker.ComputeCurrentRate(1000u));
+
+  // Send a bunch of data at a constant rate for 5.5 "seconds".
+  // We should report the rate properly.
+  for (int i = 0; i < 5500; i += 100) {
+    tracker.AddSamples(9876U);
+    tracker.AdvanceTime(100);
+  }
+  EXPECT_EQ(9876U * 10, tracker.ComputeCurrentRate(1000u));
+
+  // Advance the clock by 500 ms. Since we sent nothing over this half-second,
+  // the reported rate should be reduced by half.
+  tracker.AdvanceTime(500);
+  EXPECT_EQ(9876U * 5, tracker.ComputeCurrentRate(1000u));
+}
+
+TEST(BucketRateTrackerTest, TestGetUnitSecondsAfterInitialValue) {
+  BucketRateTrackerForTest tracker;
+  tracker.AddSamples(1234);
+  tracker.AdvanceTime(1000);
+  EXPECT_EQ(1234u, tracker.ComputeCurrentRate(1000u));
+}
+
+class IntervalRateTrackerForTest : public IntervalRateTracker {
+ public:
+  IntervalRateTrackerForTest() : IntervalRateTracker(15u), time_(0) {}
+  virtual uint32 Time() const { return time_; }
+  void AdvanceTime(uint32 delta) { time_ += delta; }
+
+ private:
+  uint32 time_;
+};
+
+TEST(IntervalRateTrackerTest, Test30FPS) {
+  IntervalRateTrackerForTest tracker;
+
+  for (int i = 0; i < 30*30; ++i) {
+    tracker.AddSamples(1);
+    tracker.AdvanceTime(33);
+    if (i % 3 == 0) {
+      tracker.AdvanceTime(1);
+    }
+  }
+  EXPECT_EQ(30u, tracker.ComputeCurrentRate(1000u));
+}
+
+}  // namespace rtc