Fix: when SamplesStatsCounter is empty it's not propagated to the Histogram perf output

Bug: None
Change-Id: I5664c39ed702b8ca581d28a08900f7a7d435d6ac
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/212610
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33512}

test/testsupport/perf_test.cc

@@ -18,6 +18,7 @@
 #include <vector>
 
 #include "absl/strings/string_view.h"
+#include "api/numerics/samples_stats_counter.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/strings/string_builder.h"
 #include "rtc_base/synchronization/mutex.h"
@@ -298,6 +299,10 @@ void PrintResult(absl::string_view measurement,
   for (size_t i = 0; i < timed_samples.size(); ++i) {
     samples[i] = timed_samples[i].value;
   }
+  // If we have an empty counter, default it to 0.
+  if (samples.empty()) {
+    samples.push_back(0);
+  }
 
   GetPerfWriter().LogResultList(graph_name.str(), trace, samples, units,
                                 important, improve_direction);

test/testsupport/perf_test_histogram_writer.cc

@@ -16,6 +16,7 @@
 #include <memory>
 
 #include "absl/strings/string_view.h"
+#include "api/numerics/samples_stats_counter.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/strings/string_builder.h"
 #include "rtc_base/synchronization/mutex.h"

test/testsupport/perf_test_unittest.cc

@@ -103,6 +103,83 @@ TEST_F(PerfTest, TestGetPerfResultsHistograms) {
   EXPECT_EQ(hist2.unit().unit(), proto::MS_BEST_FIT_FORMAT);
 }
 
+TEST_F(PerfTest, TestGetPerfResultsHistogramsWithEmptyCounter) {
+  ClearPerfResults();
+  ::testing::internal::CaptureStdout();
+
+  SamplesStatsCounter empty_counter;
+  PrintResult("measurement", "_modifier", "story", empty_counter, "ms", false);
+
+  proto::HistogramSet histogram_set;
+  EXPECT_TRUE(histogram_set.ParseFromString(GetPerfResults()))
+      << "Expected valid histogram set";
+
+  ASSERT_EQ(histogram_set.histograms_size(), 1)
+      << "Should be one histogram: measurement_modifier";
+  const proto::Histogram& hist = histogram_set.histograms(0);
+
+  EXPECT_EQ(hist.name(), "measurement_modifier");
+
+  // Spot check some things in here (there's a more thorough test on the
+  // histogram writer itself).
+  EXPECT_EQ(hist.unit().unit(), proto::MS_BEST_FIT_FORMAT);
+  EXPECT_EQ(hist.sample_values_size(), 1);
+  EXPECT_EQ(hist.sample_values(0), 0);
+
+  EXPECT_EQ(hist.diagnostics().diagnostic_map().count("stories"), 1u);
+  const proto::Diagnostic& stories =
+      hist.diagnostics().diagnostic_map().at("stories");
+  ASSERT_EQ(stories.generic_set().values_size(), 1);
+  EXPECT_EQ(stories.generic_set().values(0), "\"story\"");
+
+  std::string expected = "RESULT measurement_modifier: story= {0,0} ms\n";
+  EXPECT_EQ(expected, ::testing::internal::GetCapturedStdout());
+}
+
+TEST_F(PerfTest, TestGetPerfResultsHistogramsWithStatsCounter) {
+  ClearPerfResults();
+  ::testing::internal::CaptureStdout();
+
+  SamplesStatsCounter counter;
+  counter.AddSample(1);
+  counter.AddSample(2);
+  counter.AddSample(3);
+  counter.AddSample(4);
+  counter.AddSample(5);
+  PrintResult("measurement", "_modifier", "story", counter, "ms", false);
+
+  proto::HistogramSet histogram_set;
+  EXPECT_TRUE(histogram_set.ParseFromString(GetPerfResults()))
+      << "Expected valid histogram set";
+
+  ASSERT_EQ(histogram_set.histograms_size(), 1)
+      << "Should be one histogram: measurement_modifier";
+  const proto::Histogram& hist = histogram_set.histograms(0);
+
+  EXPECT_EQ(hist.name(), "measurement_modifier");
+
+  // Spot check some things in here (there's a more thorough test on the
+  // histogram writer itself).
+  EXPECT_EQ(hist.unit().unit(), proto::MS_BEST_FIT_FORMAT);
+  EXPECT_EQ(hist.sample_values_size(), 5);
+  EXPECT_EQ(hist.sample_values(0), 1);
+  EXPECT_EQ(hist.sample_values(1), 2);
+  EXPECT_EQ(hist.sample_values(2), 3);
+  EXPECT_EQ(hist.sample_values(3), 4);
+  EXPECT_EQ(hist.sample_values(4), 5);
+
+  EXPECT_EQ(hist.diagnostics().diagnostic_map().count("stories"), 1u);
+  const proto::Diagnostic& stories =
+      hist.diagnostics().diagnostic_map().at("stories");
+  ASSERT_EQ(stories.generic_set().values_size(), 1);
+  EXPECT_EQ(stories.generic_set().values(0), "\"story\"");
+
+  // mean = 3; std = sqrt(2)
+  std::string expected =
+      "RESULT measurement_modifier: story= {3,1.4142136} ms\n";
+  EXPECT_EQ(expected, ::testing::internal::GetCapturedStdout());
+}
+
 #endif  // WEBRTC_ENABLE_PROTOBUF
 
 #if GTEST_HAS_DEATH_TEST