Extend Histogram class to support custom range definitions

Some users have a small sparsely separated enumerated list
of plausible samples which don't fit well into a default
(log space) histogarm, or a consistently spaced (LinearHistogram).

This implementation does not yet support renderer histograms of this
sort, but it at least unblocks the dependent bug that needs support
for these sparse histograms in the browser.

The bulk of this patch was written by Raman Tenetti, in CL 1706012.

BUG=40953
r=eroman
Review URL: http://codereview.chromium.org/1737017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@45998 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 90 insertions, 5 deletions

diff --git a/base/histogram_unittest.cc b/base/histogram_unittest.cc
index f702a2e..56c733b 100644
--- a/base/histogram_unittest.cc
+++ b/base/histogram_unittest.cc
@@ -29,6 +29,17 @@ TEST(HistogramTest, StartupShutdownTest) {
   scoped_refptr<Histogram> linear_histogram1 = LinearHistogram::FactoryGet(
       "Test1LinearHistogram", 1, 1000, 10, Histogram::kNoFlags);
 
+  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);
+
   // Use standard macros (but with fixed samples)
   HISTOGRAM_TIMES("Test2Histogram", TimeDelta::FromDays(1));
   HISTOGRAM_COUNTS("Test3Histogram", 30);
@@ -74,32 +85,51 @@ TEST(HistogramTest, RecordedStartupTest) {
 
   scoped_refptr<Histogram> linear_histogram = LinearHistogram::FactoryGet(
       "TestLinearHistogram", 1, 1000, 10, Histogram::kNoFlags);
+  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);
   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);
+
+  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
-  EXPECT_EQ(6U, histograms.size());
+  EXPECT_EQ(7U, histograms.size());
 
   HISTOGRAM_ENUMERATION("TestEnumerationHistogram", 20, 200);
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
-  EXPECT_EQ(7U, histograms.size());
+  EXPECT_EQ(8U, histograms.size());
 
   DHISTOGRAM_TIMES("Test4Histogram", TimeDelta::FromDays(1));
   DHISTOGRAM_COUNTS("Test5Histogram", 30);
   histograms.clear();
   StatisticsRecorder::GetHistograms(&histograms);  // Load up lists
 #ifndef NDEBUG
-  EXPECT_EQ(9U, histograms.size());
+  EXPECT_EQ(10U, histograms.size());
 #else
-  EXPECT_EQ(7U, histograms.size());
+  EXPECT_EQ(8U, histograms.size());
 #endif
 }
 
@@ -164,10 +194,65 @@ TEST(HistogramTest, RangeTest) {
   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);
+
+  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(5U, histograms.size());
+  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);
+
+  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);
+  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;