commit 8c68845090b8ff6987866638c3891e4aacabc501
author Ilya Nikolaevskiy <ilnik@webrtc.org> Tue Sep 11 13:46:22 2018 +0200
committer Commit Bot <commit-bot@chromium.org> Wed Sep 12 08:19:37 2018 +0000
tree 2cae3b8e675a9649725be26807f9f307a1ffab6a
parent 640106e1ce35699e463fb5070f4aba2fea4beaff

Move variance calculation in SampleCounter to a new extension class

Variance calculation isn't currently used but overflow checks there may
cause unnecessary crash. Instead of completely deleting useful feature
it's now easy to disable it by choosing an appropriate Counter class.

Bug: None
Change-Id: Ifa8bbf2d023553504caa768e08e59ebccfb2fbb4
Reviewed-on: https://webrtc-review.googlesource.com/99561
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24699}

rtc_base/numerics/sample_counter_unittest.cc

diff --git a/rtc_base/numerics/sample_counter_unittest.cc b/rtc_base/numerics/sample_counter_unittest.cc
index 898f00c..4085370 100644
--- a/rtc_base/numerics/sample_counter_unittest.cc
+++ b/rtc_base/numerics/sample_counter_unittest.cc
@@ -24,7 +24,6 @@
   constexpr int kMinSamples = 1;
   SampleCounter counter;
   EXPECT_THAT(counter.Avg(kMinSamples), Eq(absl::nullopt));
-  EXPECT_THAT(counter.Avg(kMinSamples), Eq(absl::nullopt));
   EXPECT_THAT(counter.Max(), Eq(absl::nullopt));
 }
 
@@ -35,7 +34,6 @@
     counter.Add(value);
   }
   EXPECT_THAT(counter.Avg(kMinSamples), Eq(absl::nullopt));
-  EXPECT_THAT(counter.Avg(kMinSamples), Eq(absl::nullopt));
   EXPECT_THAT(counter.Max(), Eq(5));
 }
 
@@ -46,8 +44,36 @@
     counter.Add(value);
   }
   EXPECT_THAT(counter.Avg(kMinSamples), Eq(3));
-  EXPECT_THAT(counter.Variance(kMinSamples), Eq(2));
   EXPECT_THAT(counter.Max(), Eq(5));
 }
 
+TEST(SampleCounterTest, ComputesVariance) {
+  constexpr int kMinSamples = 5;
+  SampleCounterWithVariance counter;
+  for (int value : {1, 2, 3, 4, 5}) {
+    counter.Add(value);
+  }
+  EXPECT_THAT(counter.Variance(kMinSamples), Eq(2));
+}
+
+TEST(SampleCounterTest, AggregatesTwoCounters) {
+  constexpr int kMinSamples = 5;
+  SampleCounterWithVariance counter1;
+  for (int value : {1, 2, 3}) {
+    counter1.Add(value);
+  }
+  SampleCounterWithVariance counter2;
+  for (int value : {4, 5}) {
+    counter2.Add(value);
+  }
+  // Before aggregation there is not enough samples.
+  EXPECT_THAT(counter1.Avg(kMinSamples), Eq(absl::nullopt));
+  EXPECT_THAT(counter1.Variance(kMinSamples), Eq(absl::nullopt));
+  // Aggregate counter2 in counter1.
+  counter1.Add(counter2);
+  EXPECT_THAT(counter1.Avg(kMinSamples), Eq(3));
+  EXPECT_THAT(counter1.Max(), Eq(5));
+  EXPECT_THAT(counter1.Variance(kMinSamples), Eq(2));
+}
+
 }  // namespace rtc