utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize > Class Template Reference

Table of Contents

• Public Member Functions
• Detailed Description
• Constructor & Destructor Documentation
• Percentile() [1/2]
• Percentile() [2/2]
• Member Function Documentation
• Account()
• Add()
• Count()
• GetPercentile()
• operator=()
• Reset()

Class stores M buckets of type Counter and allows easy calculation of percentiles. More...

#include <userver/utils/statistics/percentile.hpp>

Public Member Functions
	Percentile (const Percentile< M, Counter, ExtraBuckets, ExtraBucketSize > &other) noexcept
Percentile &	operator= (const Percentile &rhs) noexcept
void	Account (size_t value)
	Account for another value. Value is truncated [0..M) and added to the corresponding bucket.
size_t	GetPercentile (double percent) const
	Get X percentile - min value P in [0..M) so that total number of elements in buckets 0..P is no less than X percent.
template<class Duration = std::chrono::seconds>
void	Add (const Percentile< M, Counter, ExtraBuckets, ExtraBucketSize > &other, Duration this_epoch_duration=Duration(), Duration before_this_epoch_duration=Duration())
void	Reset ()
Counter	Count () const
	Total number of elements.

Detailed Description

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>
class utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >

Class stores M buckets of type Counter and allows easy calculation of percentiles.

Bucket X stores how many elements with value X was accounted for, for the first M buckets. Bucket X stores how many elements with values [X-ExtraBucketSize/2; X+ExtraBucketSize/2) were accounted for, for the next ExtraBuckets buckets.

Template Parameters

M	how many buckets store precise value
Counter	bucket type
ExtraBuckets	how many buckets store approximated values
ExtraBucketSize	ExtraBuckets store values with this precision

See also

GetPercentile

Account

Example: Precisely count for first 500 milliseconds of execution using uint32_t counters and leave 100 buckets for all the other values with precision of 42 milliseconds:

using Percentile =
  utils::statistics::Percentile<500, std::uint32_t, 100, 42>;
 
void Account(Percentile& perc, std::chrono::milliseconds ms) {
  perc.Account(ms.count());
}
 
formats::json::Value ExtendStatistics(
  formats::json::ValueBuilder& stats_builder, Percentile& perc) {
 
  stats_builder["timings"]["1min"] = PercentileToJson(perc).ExtractValue();
 
  return stats_builder.ExtractValue();
}

Definition at line 56 of file percentile.hpp.

Constructor & Destructor Documentation

Percentile() [1/2]

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::Percentile ( )

inline

Definition at line 58 of file percentile.hpp.

Percentile() [2/2]

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::Percentile ( const Percentile< M, Counter, ExtraBuckets, ExtraBucketSize > &  other )

inlinenoexcept

Definition at line 64 of file percentile.hpp.

Member Function Documentation

Account()

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

void utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::Account ( size_t  value )

inline

Account for another value. Value is truncated [0..M) and added to the corresponding bucket.

Definition at line 91 of file percentile.hpp.

Add()

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

template<class Duration = std::chrono::seconds>

void utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::Add ( const Percentile< M, Counter, ExtraBuckets, ExtraBucketSize > &  other, Duration  this_epoch_duration = Duration(), Duration  before_this_epoch_duration = Duration()  )

inline

Definition at line 141 of file percentile.hpp.

Count()

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

Counter utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::Count ( ) const

inline

Total number of elements.

Definition at line 167 of file percentile.hpp.

GetPercentile()

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

size_t utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::GetPercentile ( double  percent ) const

inline

Get X percentile - min value P in [0..M) so that total number of elements in buckets 0..P is no less than X percent.

Parameters

percent

- value in [0..100] - requested percentile if outside of 100, then returns last bucket that has any element in it.

Definition at line 115 of file percentile.hpp.

operator=()

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

Percentile & utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::operator= ( const Percentile< M, Counter, ExtraBuckets, ExtraBucketSize > &  rhs )

inlinenoexcept

Definition at line 69 of file percentile.hpp.

Reset()

template<size_t M, typename Counter = uint32_t, size_t ExtraBuckets = 0, size_t ExtraBucketSize = 500>

void utils::statistics::Percentile< M, Counter, ExtraBuckets, ExtraBucketSize >::Reset ( )

inline

Definition at line 159 of file percentile.hpp.

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The documentation for this class was generated from the following file:

• userver/utils/statistics/percentile.hpp