text: // Copyright (c) 2011 The LevelDB Authors. All rigBTS 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_
  