Extend Histogram class to support custom range definitions...

base/histogram.cc

Index: base/histogram.cc
===================================================================
--- base/histogram.cc	(revision 45775)
+++ base/histogram.cc	(working copy)
@@ -180,7 +180,7 @@
 bool Histogram::ValidateBucketRanges() const {
   // Standard assertions that all bucket ranges should satisfy.
   DCHECK(ranges_.size() == bucket_count_ + 1);
-  DCHECK_EQ(0, ranges_[0]);
+  DCHECK_EQ(ranges_[0], 0);
   DCHECK(declared_min() == ranges_[1]);
   DCHECK(declared_max() == ranges_[bucket_count_ - 1]);
   DCHECK(kSampleType_MAX == ranges_[bucket_count_]);
@@ -194,10 +194,10 @@
   if (declared_max_ >= kSampleType_MAX)
     declared_max_ = kSampleType_MAX - 1;
   DCHECK(declared_min_ <= declared_max_);
-  DCHECK_LT(1u, bucket_count_);
+  DCHECK_GT(bucket_count_, 1u);
   size_t maximal_bucket_count = declared_max_ - declared_min_ + 2;
   DCHECK(bucket_count_ <= maximal_bucket_count);
-  DCHECK_EQ(0, ranges_[0]);
+  DCHECK_EQ(ranges_[0], 0);
   ranges_[bucket_count_] = kSampleType_MAX;
   InitializeBucketRange();
   DCHECK(ValidateBucketRanges());
@@ -325,7 +325,7 @@
                 histogram_name().c_str(),
                 sample_count);
   if (0 == sample_count) {
-    DCHECK_EQ(0, snapshot.sum());
+    DCHECK_EQ(snapshot.sum(), 0);
   } else {
     double average = static_cast<float>(snapshot.sum()) / sample_count;
     double variance = static_cast<float>(snapshot.square_sum())/sample_count
@@ -646,7 +646,7 @@
 
 
 void LinearHistogram::InitializeBucketRange() {
-  DCHECK_LT(0, declared_min());  // 0 is the underflow bucket here.
+  DCHECK_GT(declared_min(), 0);  // 0 is the underflow bucket here.
   double min = declared_min();
   double max = declared_max();
   size_t i;
@@ -691,6 +691,70 @@
 
 
 //------------------------------------------------------------------------------
+// CustomHistogram:
+//------------------------------------------------------------------------------
+
+scoped_refptr<Histogram> CustomHistogram::FactoryGet(
+    const std::string& name, const std::vector<int>& custom_ranges,
+    Flags flags) {
+  scoped_refptr<Histogram> histogram(NULL);
+
+  // Remove the duplicates in the custom ranges array.
+  std::vector<int> ranges = custom_ranges;
+  ranges.push_back(0);  // Ensure we have a zero value.
+  std::sort(ranges.begin(), ranges.end());
+  ranges.erase(std::unique(ranges.begin(), ranges.end()), ranges.end());
+  if (ranges.size() <= 1) {
+    DCHECK(false);
+    // Note that we pushed a 0 in above, so for defensive code....
+    ranges.push_back(1);  // Put in some data so we can index to [1].
+  }
+
+  DCHECK_LT(ranges.back(), kSampleType_MAX);
+
+  if (StatisticsRecorder::FindHistogram(name, &histogram)) {
+    DCHECK(histogram.get());
+    DCHECK_EQ(histogram->histogram_type(), CUSTOM_HISTOGRAM);
+  } else {
+    histogram = new CustomHistogram(name, ranges);
+    scoped_refptr<Histogram> registered_histogram(NULL);
+    StatisticsRecorder::FindHistogram(name, &registered_histogram);
+    if (registered_histogram.get() &&
+        registered_histogram.get() != histogram.get())
+      histogram = registered_histogram;
+  }
+
+  DCHECK_EQ(histogram->histogram_type(), CUSTOM_HISTOGRAM);
+  DCHECK(histogram->HasConstructorArguments(ranges[1], ranges.back(),
+                                            ranges.size()));
+  histogram->SetFlags(flags);
+  return histogram;
+}
+
+CustomHistogram::CustomHistogram(const std::string& name,
+    const std::vector<int>& custom_ranges)
+    : Histogram(name, custom_ranges[1], custom_ranges.back(),
+                custom_ranges.size()) {
+  DCHECK_GT(custom_ranges.size(), 1u);
+  DCHECK_EQ(custom_ranges[0], 0);
+  ranges_vector_ = &custom_ranges;
+  InitializeBucketRange();
+  ranges_vector_ = NULL;
+  DCHECK(ValidateBucketRanges());
+}
+
+void CustomHistogram::InitializeBucketRange() {
+  DCHECK(ranges_vector_->size() <= bucket_count());
+  for (size_t index = 0; index < ranges_vector_->size(); ++index) {
+    SetBucketRange(index, (*ranges_vector_)[index]);
+  }
+}
+
+double CustomHistogram::GetBucketSize(Count current, size_t i) const {
+  return 1;
+}
+
+//------------------------------------------------------------------------------
 // The next section handles global (central) support for all histograms, as well
 // as startup/teardown of this service.
 //------------------------------------------------------------------------------