Add implementation in metrics.h that uses atomic pointer.

webrtc/system_wrappers/source/metrics_unittest.cc

+/*
+ *  Copyright (c) 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 "testing/gtest/include/gtest/gtest.h"
+
+#include "webrtc/system_wrappers/include/metrics.h"
+#include "webrtc/test/histogram.h"
+
+namespace webrtc {
+namespace {
+const int kSample = 22;
+const std::string kName = "Name";
+
+void AddSparseSample(const std::string& name, int sample) {
+  RTC_HISTOGRAM_COUNTS_SPARSE_100(name, sample);
+}
+#if GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+void AddSample(const std::string& name, int sample) {
+  RTC_HISTOGRAM_COUNTS_100(name, sample);
+}
+#endif  // GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+}  // namespace
+
+TEST(MetricsTest, InitiallyNoSamples) {
+  test::ClearHistograms();
+  EXPECT_EQ(0, test::NumHistogramSamples(kName));
+  EXPECT_EQ(-1, test::LastHistogramSample(kName));
+}
+
+TEST(MetricsTest, RtcHistogramPercent_AddSample) {
+  test::ClearHistograms();
+  RTC_HISTOGRAM_PERCENTAGE(kName, kSample);
+  EXPECT_EQ(1, test::NumHistogramSamples(kName));
+  EXPECT_EQ(kSample, test::LastHistogramSample(kName));
+}
+
+TEST(MetricsTest, RtcHistogramEnumeration_AddSample) {
+  test::ClearHistograms();
+  RTC_HISTOGRAM_ENUMERATION(kName, kSample, kSample + 1);
+  EXPECT_EQ(1, test::NumHistogramSamples(kName));
+  EXPECT_EQ(kSample, test::LastHistogramSample(kName));
+}
+
+TEST(MetricsTest, RtcHistogramCountsSparse_AddSample) {
+  test::ClearHistograms();
+  RTC_HISTOGRAM_COUNTS_SPARSE_100(kName, kSample);
+  EXPECT_EQ(1, test::NumHistogramSamples(kName));
+  EXPECT_EQ(kSample, test::LastHistogramSample(kName));
+}
+
+TEST(MetricsTest, RtcHistogramCounts_AddSample) {
+  test::ClearHistograms();
+  RTC_HISTOGRAM_COUNTS_100(kName, kSample);
+  EXPECT_EQ(1, test::NumHistogramSamples(kName));
+  EXPECT_EQ(kSample, test::LastHistogramSample(kName));
+}
+
+TEST(MetricsTest, RtcHistogramCounts_AddMultipleSamples) {
+  test::ClearHistograms();
+  const int kNumSamples = 10;
+  for (int i = 0; i < kNumSamples; ++i) {
+    RTC_HISTOGRAM_COUNTS_100(kName, i);
+  }
+  EXPECT_EQ(kNumSamples, test::NumHistogramSamples(kName));
+  EXPECT_EQ(kNumSamples - 1, test::LastHistogramSample(kName));
+}
+
+TEST(MetricsTest, RtcHistogramSparse_NonConstantNameWorks) {
+  test::ClearHistograms();
+  AddSparseSample("Name1", kSample);
+  AddSparseSample("Name2", kSample);
+  EXPECT_EQ(1, test::NumHistogramSamples("Name1"));
+  EXPECT_EQ(1, test::NumHistogramSamples("Name2"));
+}
+
+#if GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+TEST(MetricsTest, RtcHistogram_FailsForNonConstantName) {
+  test::ClearHistograms();
+  AddSample("Name1", kSample);
+  EXPECT_DEATH(AddSample("Name2", kSample), "");
+}
+#endif  // GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+
+}  // namespace webrtc