Merge pull request #80 from khabinov/khabinov/fix-histogram-boundaries

Histogram boundary value should be inclusive

Author: jupp0r

lib/histogram.cc

@@ -17,7 +17,7 @@ void Histogram::Observe(double value) {
   auto bucket_index = static_cast<std::size_t>(std::distance(
       bucket_boundaries_.begin(),
       std::find_if(bucket_boundaries_.begin(), bucket_boundaries_.end(),
-                   [value](double boundary) { return boundary > value; })));
+                   [value](double boundary) { return boundary >= value; })));
   sum_.Increment(value);
   bucket_counts_[bucket_index].Increment();
 }

tests/histogram_test.cc

@@ -74,14 +74,16 @@ TEST_F(HistogramTest, cumulative_bucket_count) {
   Histogram histogram{{1, 2}};
   histogram.Observe(0);
   histogram.Observe(0.5);
+  histogram.Observe(1);
   histogram.Observe(1.5);
   histogram.Observe(1.5);
+  histogram.Observe(2);
   histogram.Observe(3);
   auto metric = histogram.Collect();
   ASSERT_TRUE(metric.has_histogram());
   auto h = metric.histogram();
   ASSERT_EQ(h.bucket_size(), 3);
-  EXPECT_EQ(h.bucket(0).cumulative_count(), 2);
-  EXPECT_EQ(h.bucket(1).cumulative_count(), 4);
-  EXPECT_EQ(h.bucket(2).cumulative_count(), 5);
+  EXPECT_EQ(h.bucket(0).cumulative_count(), 3);
+  EXPECT_EQ(h.bucket(1).cumulative_count(), 6);
+  EXPECT_EQ(h.bucket(2).cumulative_count(), 7);
 }