Source release v3.5.0

metrics/include/distribution.h

@@ -0,0 +1,53 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// This file contains the definition of a Distribution class which computes
+// the distribution values of a series of samples.
+
+#ifndef WVCDM_METRICS_DISTRIBUTION_H_
+#define WVCDM_METRICS_DISTRIBUTION_H_
+
+#include <stdint.h>
+
+namespace wvcdm {
+namespace metrics {
+
+// The Distribution class holds statistics about a series of values that the
+// client provides via the Record method. A caller will call Record once for
+// each of the values in a series. The Distribution instance will calculate the
+// mean, count, min, max and variance of the distribution.
+//
+// Example usage:
+//   Distribution dist;
+//   dist.Record(1);
+//   dist.Record(2);
+//   dist.Mean();  // Returns 1.5.
+//   dist.Count();  // Returns 2.
+class Distribution {
+ public:
+  Distribution();
+
+  // Uses the provided sample value to update the computed statistics.
+  void Record(double value);
+
+  // Return the value for each of the stats computed about the series of
+  // values (min, max, count, etc.).
+  double Min() const { return min_; }
+  double Max() const { return max_; }
+  double Mean() const { return mean_; }
+  int64_t Count() const { return count_; }
+  double Variance() const {
+    return count_ == 0 ? 0.0 : sum_squared_deviation_ / count_;
+  }
+
+ private:
+  int64_t count_;
+  double min_;
+  double max_;
+  double mean_;
+  double sum_squared_deviation_;
+};
+
+}  // namespace metrics
+}  // namespace wvcdm
+
+#endif  // WVCDM_METRICS_DISTRIBUTION_H_