intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 68 insertions, 0 deletions

diff --git a/library/cpp/monlib/metrics/histogram_collector_exponential.cpp b/library/cpp/monlib/metrics/histogram_collector_exponential.cpp
new file mode 100644
index 0000000000..2f8a50a5f9
--- /dev/null
+++ b/library/cpp/monlib/metrics/histogram_collector_exponential.cpp
@@ -0,0 +1,68 @@
+#include "histogram_collector.h"
+#include "atomics_array.h"
+
+#include <util/generic/algorithm.h>
+#include <util/generic/vector.h>
+#include <util/generic/yexception.h>
+#include <util/generic/ylimits.h>
+
+namespace NMonitoring {
+    ///////////////////////////////////////////////////////////////////////////
+    // TExponentialHistogramCollector
+    ///////////////////////////////////////////////////////////////////////////
+    class TExponentialHistogramCollector: public IHistogramCollector {
+    public:
+        TExponentialHistogramCollector(ui32 bucketsCount, double base, double scale)
+            : Values_(bucketsCount)
+            , Base_(base)
+            , Scale_(scale)
+            , MinValue_(scale)
+            , MaxValue_(scale * std::pow(base, bucketsCount - 2))
+            , LogOfBase_(std::log(base))
+        {
+        }
+
+        void Collect(double value, ui32 count) override {
+            ui32 index = Max<ui32>();
+            if (value <= MinValue_) {
+                index = 0;
+            } else if (value > MaxValue_) {
+                index = Values_.Size() - 1;
+            } else {
+                double logBase = std::log(value / Scale_) / LogOfBase_;
+                index = static_cast<ui32>(std::ceil(logBase));
+            }
+            Values_.Add(index, count);
+        }
+
+        void Reset() override {
+            Values_.Reset();
+        }
+
+        IHistogramSnapshotPtr Snapshot() const override {
+            return new TExponentialHistogramSnapshot(Base_, Scale_, Values_.Copy());
+        }
+
+    private:
+        TAtomicsArray Values_;
+        double Base_;
+        double Scale_;
+        TBucketBound MinValue_;
+        TBucketBound MaxValue_;
+        double LogOfBase_;
+    };
+
+    IHistogramCollectorPtr ExponentialHistogram(
+        ui32 bucketsCount, double base, double scale)
+    {
+        Y_ENSURE(bucketsCount >= 2,
+                 "exponential histogram must contain at least two buckets");
+        Y_ENSURE(bucketsCount <= HISTOGRAM_MAX_BUCKETS_COUNT,
+                 "buckets count must be <=" << HISTOGRAM_MAX_BUCKETS_COUNT
+                                            << ", but got: " << bucketsCount);
+        Y_ENSURE(base > 1.0, "base must be > 1.0, got: " << base);
+        Y_ENSURE(scale >= 1.0, "scale must be >= 1.0, got: " << scale);
+
+        return MakeHolder<TExponentialHistogramCollector>(bucketsCount, base, scale);
+    }
+}