rocksdb/util/histogram.h
Abhishek Kona fe10200ddc Introduce histogram in statistics.h
Summary:
* Introduce is histogram in statistics.h
* stop watch to measure time.
* introduce two timers as a poc.
Replaced NULL with nullptr to fight some lint errors
Should be useful for google.

Test Plan:
ran db_bench and check stats.
make all check

Reviewers: dhruba, heyongqiang

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8637
2013-02-20 10:43:32 -08:00

80 lines
1.8 KiB
C++

// 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 "leveldb/statistics.h"
#include <cassert>
#include <string>
#include <vector>
#include <map>
namespace leveldb {
class HistogramBucketMapper {
public:
HistogramBucketMapper();
// converts a value to the bucket index.
const size_t IndexForValue(const uint64_t value) const;
// number of buckets required.
const size_t BucketCount() const {
return bucketValues_.size();
}
uint64_t LastValue() const {
return maxBucketValue_;
}
uint64_t FirstValue() const {
return minBucketValue_;
}
uint64_t BucketLimit(const uint64_t bucketNumber) const {
assert(bucketNumber < BucketCount());
return bucketValues_[bucketNumber];
}
private:
const std::vector<uint64_t> bucketValues_;
const uint64_t maxBucketValue_;
const uint64_t minBucketValue_;
std::map<uint64_t, uint64_t> valueIndexMap_;
};
class HistogramImpl {
public:
HistogramImpl();
virtual ~HistogramImpl() {}
virtual void Clear();
virtual void Add(uint64_t value);
virtual void Add(double value);
void Merge(const HistogramImpl& other);
virtual std::string ToString() const;
virtual double Median() const;
virtual double Percentile(double p) const;
virtual double Average() const;
virtual double StandardDeviation() const;
virtual void Data(HistogramData * const data) const;
private:
double min_;
double max_;
double num_;
double sum_;
double sum_squares_;
std::vector<uint64_t> buckets_;
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_UTIL_HISTOGRAM_H_