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rocksdb/util/histogram.h

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1.6 KiB

// 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 <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 Histogram {
public:
Histogram();
void Clear();
void Add(uint64_t value);
void Add(double value);
void Merge(const Histogram& other);
std::string ToString() const;
double Median() const;
double Percentile(double p) const;
double Average() const;
double StandardDeviation() 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_