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+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_UTIL_HISTOGRAM_H_
+#define STORAGE_LEVELDB_UTIL_HISTOGRAM_H_
+
+#include <string>
+
+namespace leveldb {
+
+class Histogram {
+ public:
+ Histogram() { }
+ ~Histogram() { }
+
+ void Clear();
+ void Add(double value);
+ void Merge(const Histogram& other);
+
+ std::string ToString() const;
+
+ private:
+ double min_;
+ double max_;
+ double num_;
+ double sum_;
+ double sum_squares_;
+
+ enum { kNumBuckets = 154 };
+ static const double kBucketLimit[kNumBuckets];
+ double buckets_[kNumBuckets];
+
+ double Median() const;
+ double Percentile(double p) const;
+ double Average() const;
+ double StandardDeviation() const;
+};
+
+} // namespace leveldb
+
+#endif // STORAGE_LEVELDB_UTIL_HISTOGRAM_H_