Use lock-free lazy initialization for static histogram references

base/metrics/histogram_unittest.cc

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Test of Histogram class
 
 #include "base/metrics/histogram.h"
+#include "base/scoped_ptr.h"
 #include "base/time.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 namespace {
 
 class HistogramTest : public testing::Test {
 };
 
 // Check for basic syntax and use.
 TEST(HistogramTest, StartupShutdownTest) {
   // Try basic construction
-  scoped_refptr<Histogram> histogram = Histogram::FactoryGet(
-      "TestHistogram", 1, 1000, 10, Histogram::kNoFlags);
-  scoped_refptr<Histogram> histogram1 = Histogram::FactoryGet(
-      "Test1Histogram", 1, 1000, 10, Histogram::kNoFlags);
+  Histogram* histogram(Histogram::FactoryGet(
+      "TestHistogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), histogram);
+  Histogram* histogram1(Histogram::FactoryGet(
+      "Test1Histogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), histogram1);
+  EXPECT_NE(histogram, histogram1);
 
-  scoped_refptr<Histogram> linear_histogram = LinearHistogram::FactoryGet(
-      "TestLinearHistogram", 1, 1000, 10, Histogram::kNoFlags);
-  scoped_refptr<Histogram> linear_histogram1 = LinearHistogram::FactoryGet(
-      "Test1LinearHistogram", 1, 1000, 10, Histogram::kNoFlags);
+
+  Histogram* linear_histogram(LinearHistogram::FactoryGet(
+      "TestLinearHistogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), linear_histogram);
+  Histogram* linear_histogram1(LinearHistogram::FactoryGet(
+      "Test1LinearHistogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), linear_histogram1);
+  EXPECT_NE(linear_histogram, linear_histogram1);
 
   std::vector<int> custom_ranges;
   custom_ranges.push_back(1);
   custom_ranges.push_back(5);
   custom_ranges.push_back(10);
   custom_ranges.push_back(20);
   custom_ranges.push_back(30);
-  scoped_refptr<Histogram> custom_histogram = CustomHistogram::FactoryGet(
-      "TestCustomHistogram", custom_ranges, Histogram::kNoFlags);
-  scoped_refptr<Histogram> custom_histogram1 = CustomHistogram::FactoryGet(
-      "Test1CustomHistogram", custom_ranges, Histogram::kNoFlags);
+  Histogram* custom_histogram(CustomHistogram::FactoryGet(
+      "TestCustomHistogram", custom_ranges, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), custom_histogram);
+  Histogram* custom_histogram1(CustomHistogram::FactoryGet(
+      "Test1CustomHistogram", custom_ranges, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), custom_histogram1);
 
   // Use standard macros (but with fixed samples)
   HISTOGRAM_TIMES("Test2Histogram", TimeDelta::FromDays(1));
   HISTOGRAM_COUNTS("Test3Histogram", 30);
 
   DHISTOGRAM_TIMES("Test4Histogram", TimeDelta::FromDays(1));
   DHISTOGRAM_COUNTS("Test5Histogram", 30);
 
   HISTOGRAM_ENUMERATION("Test6Histogram", 129, 130);
 
@@ skipping 13 matching lines @@
 TEST(HistogramTest, RecordedStartupTest) {
   // Test a statistics recorder, by letting histograms register.
   StatisticsRecorder recorder;  // This initializes the global state.
 
   StatisticsRecorder::Histograms histograms;
   EXPECT_EQ(0U, histograms.size());
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
   EXPECT_EQ(0U, histograms.size());
 
   // Try basic construction
-  scoped_refptr<Histogram> histogram = Histogram::FactoryGet(
-      "TestHistogram", 1, 1000, 10, Histogram::kNoFlags);
+  Histogram* histogram(Histogram::FactoryGet(
+      "TestHistogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), histogram);
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
   EXPECT_EQ(1U, histograms.size());
-  scoped_refptr<Histogram> histogram1 = Histogram::FactoryGet(
-      "Test1Histogram", 1, 1000, 10, Histogram::kNoFlags);
+  Histogram* histogram1(Histogram::FactoryGet(
+      "Test1Histogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), histogram1);
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
   EXPECT_EQ(2U, histograms.size());
 
-  scoped_refptr<Histogram> linear_histogram = LinearHistogram::FactoryGet(
-      "TestLinearHistogram", 1, 1000, 10, Histogram::kNoFlags);
+  Histogram* linear_histogram(LinearHistogram::FactoryGet(
+      "TestLinearHistogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), linear_histogram);
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
   EXPECT_EQ(3U, histograms.size());
 
-  scoped_refptr<Histogram> linear_histogram1 = LinearHistogram::FactoryGet(
-      "Test1LinearHistogram", 1, 1000, 10, Histogram::kNoFlags);
+  Histogram* linear_histogram1(LinearHistogram::FactoryGet(
+      "Test1LinearHistogram", 1, 1000, 10, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), linear_histogram1);
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
   EXPECT_EQ(4U, histograms.size());
 
   std::vector<int> custom_ranges;
   custom_ranges.push_back(1);
   custom_ranges.push_back(5);
   custom_ranges.push_back(10);
   custom_ranges.push_back(20);
   custom_ranges.push_back(30);
-  scoped_refptr<Histogram> custom_histogram = CustomHistogram::FactoryGet(
-      "TestCustomHistogram", custom_ranges, Histogram::kNoFlags);
-  scoped_refptr<Histogram> custom_histogram1 = CustomHistogram::FactoryGet(
-      "TestCustomHistogram", custom_ranges, Histogram::kNoFlags);
+  Histogram* custom_histogram(CustomHistogram::FactoryGet(
+      "TestCustomHistogram", custom_ranges, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), custom_histogram);
+  Histogram* custom_histogram1(CustomHistogram::FactoryGet(
+      "TestCustomHistogram", custom_ranges, Histogram::kNoFlags));
+  EXPECT_NE(reinterpret_cast<Histogram*>(NULL), custom_histogram1);
 
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
   EXPECT_EQ(5U, histograms.size());
 
   // Use standard macros (but with fixed samples)
   HISTOGRAM_TIMES("Test2Histogram", TimeDelta::FromDays(1));
   HISTOGRAM_COUNTS("Test3Histogram", 30);
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
@@ skipping 15 matching lines @@
 #endif
 }
 
 TEST(HistogramTest, RangeTest) {
   StatisticsRecorder recorder;
   StatisticsRecorder::Histograms histograms;
 
   recorder.GetHistograms(&histograms);
   EXPECT_EQ(0U, histograms.size());
 
-  scoped_refptr<Histogram> histogram = Histogram::FactoryGet(
-      "Histogram", 1, 64, 8, Histogram::kNoFlags);  // As per header file.
+  Histogram* histogram(Histogram::FactoryGet(
+      "Histogram", 1, 64, 8, Histogram::kNoFlags));  // As per header file.
   // Check that we got a nice exponential when there was enough rooom.
   EXPECT_EQ(0, histogram->ranges(0));
   int power_of_2 = 1;
   for (int i = 1; i < 8; i++) {
     EXPECT_EQ(power_of_2, histogram->ranges(i));
     power_of_2 *= 2;
   }
   EXPECT_EQ(INT_MAX, histogram->ranges(8));
 
-  scoped_refptr<Histogram> short_histogram = Histogram::FactoryGet(
-      "Histogram Shortened", 1, 7, 8, Histogram::kNoFlags);
+  Histogram* short_histogram(Histogram::FactoryGet(
+      "Histogram Shortened", 1, 7, 8, Histogram::kNoFlags));
   // Check that when the number of buckets is short, we get a linear histogram
   // for lack of space to do otherwise.
   for (int i = 0; i < 8; i++)
     EXPECT_EQ(i, short_histogram->ranges(i));
   EXPECT_EQ(INT_MAX, short_histogram->ranges(8));
 
-  scoped_refptr<Histogram> linear_histogram = LinearHistogram::FactoryGet(
-      "Linear", 1, 7, 8, Histogram::kNoFlags);
+  Histogram* linear_histogram(LinearHistogram::FactoryGet(
+      "Linear", 1, 7, 8, Histogram::kNoFlags));
   // We also get a nice linear set of bucket ranges when we ask for it
   for (int i = 0; i < 8; i++)
     EXPECT_EQ(i, linear_histogram->ranges(i));
   EXPECT_EQ(INT_MAX, linear_histogram->ranges(8));
 
-  scoped_refptr<Histogram> linear_broad_histogram = LinearHistogram::FactoryGet(
-      "Linear widened", 2, 14, 8, Histogram::kNoFlags);
+  Histogram* linear_broad_histogram(LinearHistogram::FactoryGet(
+      "Linear widened", 2, 14, 8, Histogram::kNoFlags));
   // ...but when the list has more space, then the ranges naturally spread out.
   for (int i = 0; i < 8; i++)
     EXPECT_EQ(2 * i, linear_broad_histogram->ranges(i));
   EXPECT_EQ(INT_MAX, linear_broad_histogram->ranges(8));
 
-  scoped_refptr<Histogram> transitioning_histogram =
-      Histogram::FactoryGet("LinearAndExponential", 1, 32, 15,
-                                      Histogram::kNoFlags);
+  Histogram* transitioning_histogram(Histogram::FactoryGet(
+      "LinearAndExponential", 1, 32, 15, Histogram::kNoFlags));
   // When space is a little tight, we transition from linear to exponential.
   EXPECT_EQ(0, transitioning_histogram->ranges(0));
   EXPECT_EQ(1, transitioning_histogram->ranges(1));
   EXPECT_EQ(2, transitioning_histogram->ranges(2));
   EXPECT_EQ(3, transitioning_histogram->ranges(3));
   EXPECT_EQ(4, transitioning_histogram->ranges(4));
   EXPECT_EQ(5, transitioning_histogram->ranges(5));
   EXPECT_EQ(6, transitioning_histogram->ranges(6));
   EXPECT_EQ(7, transitioning_histogram->ranges(7));
   EXPECT_EQ(9, transitioning_histogram->ranges(8));
   EXPECT_EQ(11, transitioning_histogram->ranges(9));
   EXPECT_EQ(14, transitioning_histogram->ranges(10));
   EXPECT_EQ(17, transitioning_histogram->ranges(11));
   EXPECT_EQ(21, transitioning_histogram->ranges(12));
   EXPECT_EQ(26, transitioning_histogram->ranges(13));
   EXPECT_EQ(32, transitioning_histogram->ranges(14));
   EXPECT_EQ(INT_MAX, transitioning_histogram->ranges(15));
 
   std::vector<int> custom_ranges;
   custom_ranges.push_back(0);
   custom_ranges.push_back(9);
   custom_ranges.push_back(10);
   custom_ranges.push_back(11);
   custom_ranges.push_back(300);
-  scoped_refptr<Histogram> test_custom_histogram = CustomHistogram::FactoryGet(
-      "TestCustomRangeHistogram", custom_ranges, Histogram::kNoFlags);
+  Histogram* test_custom_histogram(CustomHistogram::FactoryGet(
+      "TestCustomRangeHistogram", custom_ranges, Histogram::kNoFlags));
 
   EXPECT_EQ(custom_ranges[0], test_custom_histogram->ranges(0));
   EXPECT_EQ(custom_ranges[1], test_custom_histogram->ranges(1));
   EXPECT_EQ(custom_ranges[2], test_custom_histogram->ranges(2));
   EXPECT_EQ(custom_ranges[3], test_custom_histogram->ranges(3));
   EXPECT_EQ(custom_ranges[4], test_custom_histogram->ranges(4));
 
   recorder.GetHistograms(&histograms);
   EXPECT_EQ(6U, histograms.size());
 }
 
 TEST(HistogramTest, CustomRangeTest) {
   StatisticsRecorder recorder;
   StatisticsRecorder::Histograms histograms;
 
   // Check that missing leading zero is handled by an auto-insertion.
   std::vector<int> custom_ranges;
   // Don't include a zero.
   custom_ranges.push_back(9);
   custom_ranges.push_back(10);
   custom_ranges.push_back(11);
-  scoped_refptr<Histogram> test_custom_histogram = CustomHistogram::FactoryGet(
-      "TestCustomRangeHistogram", custom_ranges, Histogram::kNoFlags);
+  Histogram* test_custom_histogram(CustomHistogram::FactoryGet(
+      "TestCustomRangeHistogram", custom_ranges, Histogram::kNoFlags));
 
   EXPECT_EQ(0, test_custom_histogram->ranges(0));  // Auto added
   EXPECT_EQ(custom_ranges[0], test_custom_histogram->ranges(1));
   EXPECT_EQ(custom_ranges[1], test_custom_histogram->ranges(2));
   EXPECT_EQ(custom_ranges[2], test_custom_histogram->ranges(3));
 
   // Check that unsorted data with dups is handled gracefully.
   const int kSmall = 7;
   const int kMid = 8;
   const int kBig = 9;
   custom_ranges.clear();
   custom_ranges.push_back(kBig);
   custom_ranges.push_back(kMid);
   custom_ranges.push_back(kSmall);
   custom_ranges.push_back(kSmall);
   custom_ranges.push_back(kMid);
   custom_ranges.push_back(0);  // Push an explicit zero.
   custom_ranges.push_back(kBig);
 
-  scoped_refptr<Histogram> unsorted_histogram = CustomHistogram::FactoryGet(
-      "TestCustomUnsortedDupedHistogram", custom_ranges, Histogram::kNoFlags);
+  Histogram* unsorted_histogram(CustomHistogram::FactoryGet(
+      "TestCustomUnsortedDupedHistogram", custom_ranges, Histogram::kNoFlags));
   EXPECT_EQ(0, unsorted_histogram->ranges(0));
   EXPECT_EQ(kSmall, unsorted_histogram->ranges(1));
   EXPECT_EQ(kMid, unsorted_histogram->ranges(2));
   EXPECT_EQ(kBig, unsorted_histogram->ranges(3));
 }
 
 
 // Make sure histogram handles out-of-bounds data gracefully.
 TEST(HistogramTest, BoundsTest) {
   const size_t kBucketCount = 50;
-  scoped_refptr<Histogram> histogram = Histogram::FactoryGet(
-      "Bounded", 10, 100, kBucketCount, Histogram::kNoFlags);
+  Histogram* histogram(Histogram::FactoryGet(
+      "Bounded", 10, 100, kBucketCount, Histogram::kNoFlags));
 
   // Put two samples "out of bounds" above and below.
   histogram->Add(5);
   histogram->Add(-50);
 
   histogram->Add(100);
   histogram->Add(10000);
 
   // Verify they landed in the underflow, and overflow buckets.
   Histogram::SampleSet sample;
   histogram->SnapshotSample(&sample);
   EXPECT_EQ(2, sample.counts(0));
   EXPECT_EQ(0, sample.counts(1));
   size_t array_size = histogram->bucket_count();
   EXPECT_EQ(kBucketCount, array_size);
   EXPECT_EQ(0, sample.counts(array_size - 2));
   EXPECT_EQ(2, sample.counts(array_size - 1));
 }
 
 // Check to be sure samples land as expected is "correct" buckets.
 TEST(HistogramTest, BucketPlacementTest) {
-  scoped_refptr<Histogram> histogram = Histogram::FactoryGet(
-      "Histogram", 1, 64, 8, Histogram::kNoFlags);  // As per header file.
+  Histogram* histogram(Histogram::FactoryGet(
+      "Histogram", 1, 64, 8, Histogram::kNoFlags));  // As per header file.
 
   // Check that we got a nice exponential since there was enough rooom.
   EXPECT_EQ(0, histogram->ranges(0));
   int power_of_2 = 1;
   for (int i = 1; i < 8; i++) {
     EXPECT_EQ(power_of_2, histogram->ranges(i));
     power_of_2 *= 2;
   }
   EXPECT_EQ(INT_MAX, histogram->ranges(8));
 
@@ skipping 15 matching lines @@
     EXPECT_EQ(i + 1, sample.counts(i));
 }
 
 }  // namespace
 
 //------------------------------------------------------------------------------
 // We can't be an an anonymous namespace while being friends, so we pop back
 // out to the base namespace here.  We need to be friends to corrupt the
 // internals of the histogram and/or sampleset.
 TEST(HistogramTest, CorruptSampleCounts) {
-  scoped_refptr<Histogram> histogram = Histogram::FactoryGet(
-      "Histogram", 1, 64, 8, Histogram::kNoFlags);  // As per header file.
+  Histogram* histogram(Histogram::FactoryGet(
+      "Histogram", 1, 64, 8, Histogram::kNoFlags));  // As per header file.
 
   EXPECT_EQ(0, histogram->sample_.redundant_count());
   histogram->Add(20);  // Add some samples.
   histogram->Add(40);
   EXPECT_EQ(2, histogram->sample_.redundant_count());
 
   Histogram::SampleSet snapshot;
   histogram->SnapshotSample(&snapshot);
   EXPECT_EQ(Histogram::NO_INCONSISTENCIES, 0);
   EXPECT_EQ(0, histogram->FindCorruption(snapshot));  // No default corruption.
   EXPECT_EQ(2, snapshot.redundant_count());
 
   snapshot.counts_[3] += 100;  // Sample count won't match redundant count.
   EXPECT_EQ(Histogram::COUNT_LOW_ERROR, histogram->FindCorruption(snapshot));
   snapshot.counts_[2] -= 200;
   EXPECT_EQ(Histogram::COUNT_HIGH_ERROR, histogram->FindCorruption(snapshot));
 
   // But we can't spot a corruption if it is compensated for.
   snapshot.counts_[1] += 100;
   EXPECT_EQ(0, histogram->FindCorruption(snapshot));
 }
 
 TEST(HistogramTest, CorruptBucketBounds) {
-  scoped_refptr<Histogram> histogram = Histogram::FactoryGet(
-      "Histogram", 1, 64, 8, Histogram::kNoFlags);  // As per header file.
+  Histogram* histogram(Histogram::FactoryGet(
+      "Histogram", 1, 64, 8, Histogram::kNoFlags));  // As per header file.
 
   Histogram::SampleSet snapshot;
   histogram->SnapshotSample(&snapshot);
   EXPECT_EQ(Histogram::NO_INCONSISTENCIES, 0);
   EXPECT_EQ(0, histogram->FindCorruption(snapshot));  // No default corruption.
 
   std::swap(histogram->ranges_[1], histogram->ranges_[2]);
   EXPECT_EQ(Histogram::BUCKET_ORDER_ERROR | Histogram::RANGE_CHECKSUM_ERROR,
             histogram->FindCorruption(snapshot));
 
@@ skipping 24 matching lines @@
       if (checksum & 1)
         checksum = kReversedPolynomial ^ (checksum >> 1);
       else
         checksum >>= 1;
     }
     EXPECT_EQ(Histogram::kCrcTable[i], checksum);
   }
 }
 
 }  // namespace base