1// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file. See the AUTHORS file for names of contributors.
4
5#ifndef STORAGE_LEVELDB_UTIL_HISTOGRAM_H_
6#define STORAGE_LEVELDB_UTIL_HISTOGRAM_H_
7
8#include <string>
9
10namespace leveldb {
11
12class Histogram {
13 public:
14  Histogram() { }
15  ~Histogram() { }
16
17  void Clear();
18  void Add(double value);
19  void Merge(const Histogram& other);
20
21  std::string ToString() const;
22
23 private:
24  double min_;
25  double max_;
26  double num_;
27  double sum_;
28  double sum_squares_;
29
30  enum { kNumBuckets = 154 };
31  static const double kBucketLimit[kNumBuckets];
32  double buckets_[kNumBuckets];
33
34  double Median() const;
35  double Percentile(double p) const;
36  double Average() const;
37  double StandardDeviation() const;
38};
39
40}  // namespace leveldb
41
42#endif  // STORAGE_LEVELDB_UTIL_HISTOGRAM_H_
43