Efficient counter implementations for Gaudi. More...

Classes
class	AccumulatorSet
	AccumulatorSet is an Accumulator that holds a set of Accumulators templated by same Arithmetic and Atomicity and increase them altogether. More...

struct	Adder
	An Adder ValueHandler operator(a, b) means a += b. More...

struct	Adder< Arithmetic, atomicity::full >
	Adder specialization in the case of atomicity full. More...

struct	Adder< Arithmetic, atomicity::none >
	Adder specialization in the case of atomicity none. More...

struct	AveragingAccumulator
	AveragingAccumulator. More...

struct	AveragingCounter
	A counter aiming at computing sum and average. More...

struct	BaseValueHandler
	Base type for all functors used as ValuesHandler. More...

struct	BaseValueHandler< Arithmetic, atomicity::full >
	BaseValueHandler specialization in the case of atomicity full. More...

struct	BaseValueHandler< Arithmetic, atomicity::none >
	BaseValueHandler specialization in the case of atomicity none. More...

struct	BinomialAccumulator
	BinomialAccumulator. More...

struct	BinomialCounter
	A counter dealing with binomial data. More...

class	Buffer
	Buffer is a non atomic Accumulator which, when it goes out-of-scope, updates the underlying thread-safe Accumulator for all previous updates in one go. More...

struct	BufferableCounter
	An empty ancester of all counters that provides a buffer method that returns a buffer on itself. More...

struct	Constant
	An functor always returning the value N. More...

struct	CountAccumulator
	CountAccumulator. More...

struct	Counter
	A basic counter counting input values. More...

struct	Extremum
	An Extremum ValueHandler, to be reused for Minimum and Maximum operator(a, b) means if (Compare(b,a)) a = b In case of full atomicity, compare_exchange_weak is used. More...

struct	Extremum< Arithmetic, atomicity::full, Compare, Initial >
	Extremum specialization in the case of atomicity full. More...

struct	Extremum< Arithmetic, atomicity::none, Compare, Initial >
	Extremum specialization in the case of atomicity none. More...

struct	FalseAccumulator
	FalseAccumulator. More...

struct	FalseTo1
	helper functor for the FalseAccumulator More...

class	GenericAccumulator
	Generic Accumulator, templated by. More...

struct	Identity
	An Identity functor. More...

struct	MaxAccumulator
	MaxAccumulator. More...

struct	MinAccumulator
	MinAccumulator. More...

struct	PrintableCounter
	An empty ancester of all counters that knows how to print themselves. More...

struct	SigmaAccumulator
	SigmaAccumulator. More...

struct	SigmaCounter
	A counter aiming at computing average and sum2 / variance / standard deviation. More...

struct	Square
	A Square functor. More...

struct	SquareAccumulator
	SquareAccumulator. More...

struct	StatCounter
	A counter aiming at computing average and sum2 / variance / standard deviation. More...

struct	SumAccumulator
	SumAccumulator. More...

struct	TrueAccumulator
	TrueAccumulator. More...

struct	TrueTo1
	helper functor for the TrueAccumulator More...

Typedefs
template<typename T , typename = int>
using	has_fetch_add_ = decltype(std::atomic< T >{}.fetch_add(0))
	type_traits for checking the presence of fetch_add in std::atomic<T> More...

template<typename T >
using	has_fetch_add = typename Gaudi::cpp17::is_detected< has_fetch_add_, T >::value_t

template<typename Arithmetic , typename Result = double>
using	fp_result_type = std::conditional_t< std::is_integral< Arithmetic >::value, Result, Arithmetic >
	type_trait for the result type of a floating point operation on the type Arithmetic More...

template<typename Arithmetic , atomicity Atomicity = atomicity::full>
using	Minimum = Extremum< Arithmetic, Atomicity, std::less< Arithmetic >, std::numeric_limits< Arithmetic >::max >
	A Minimun ValueHandler operator(a, b) means a = min(a, b) In case of full atomicity, compare_exchange_weak is used. More...

template<typename Arithmetic , atomicity Atomicity = atomicity::full>
using	Maximum = Extremum< Arithmetic, Atomicity, std::greater< Arithmetic >, std::numeric_limits< Arithmetic >::lowest >
	An Maximum ValueHandler operator(a, b) means a = max(a, b) In case of full atomicity, compare_exchange_weak is used. More...

template<typename Arithmetic , atomicity Atomicity = atomicity::full>
using	StatAccumulator = AccumulatorSet< Arithmetic, Atomicity, SigmaAccumulator, MinAccumulator, MaxAccumulator >
	StatAccumulator. More...

template<typename Arithmetic = double, atomicity Atomicity = atomicity::full>
using	SummingCounter = AveragingCounter< Arithmetic, Atomicity >

Enumerations
enum	atomicity { atomicity::none, atomicity::full }
	Defines atomicity of the accumulators. More...

Functions
std::ostream &	operator<< (std::ostream &s, const PrintableCounter &counter)
	external printout operator to a stream type More...

MsgStream &	operator<< (MsgStream &s, const PrintableCounter &counter)

template<typename Counter , typename Container , typename Fun >
void	accumulate (Counter &counter, const Container &container, Fun f=Identity{})
	A helper function for accumulating data from a container into a counter This is internally using buffers so that the original counter is only updated once. More...

Detailed Description

Efficient counter implementations for Gaudi.

A number of concepts and templated classes are defined:

Concepts

Accumulator : object accumulating some data in some way. examples : counters, sum of squares accumulator, minimum accumulator (keeps minimum of all values)
Atomicity : the atomicity of an accumulator. Can be none or full. "none" means that the accumulator is not thread safe and should only be used locally within a thread. "full" means that the accumulator is thread safe, but that you pay the price of atomics inside. Note that this price may be reduced by the usage of the Buffer class, see below.
InputTransform : a transformation to be applied to the input of an Accumulator. for example "elevation to power 2" for a sum of squares Accumulator, "identity" for a sum Accumulator or a minimum Accumulator, "constant 1" for a pure counter
OutputTransform : a transformation to be applied to the value of an Accumulator when reading it. Usually identity. You can think of square root for an RMS Accumulator (accumulating squares internally)
ValueHandler : the class handling the internal value of an Accumulator, and responsible for updating it with a new input. It defines the initial default value, the storage type used (depending on atomicity) and the actual update operation (sum, keep min or max typically).
AccumulatorSet : an Accumulator defined as a set of Accumulators with same InputType and Atomicity. Updating it means updating all Accumulators of the set with the same value. E.g. a set with Counter and Sum will be able to compute some average
Buffer : a wrapper around a thread safe Accumulator that allows to accumulate locally (in a non thread safe Accumulator) data before merging into the original one when Buffer is destructed. To be use when accumulators are updated in tight loops
Counter : a higher level object that is an Accumulator and provides extra methods, most notably a way to print itself via operator<<, a print method and a buffer method to retrieve a Buffer on top of it.

Classes and helper functions

many classes are directly linked to concepts :
- Constant, Identity, Square are InputTransforms / OutputTransforms
- BaseValueHandler : a base class for ValueHandlers Adder, Minimum and Maximum
- Adder, Extremum, Minimum, Maximum, Binomial are ValueHandlers
- GenericAccumulator : implements a generic Accumulator. See class definition for details
- AccumulatorSet binds together a set of Accumulators into a new accumulator
- Buffer implements the local buffering of an Accumulator
some classes implements the most common Accumulators :
- MaxAccumulator : keeps the max, has a max() method
- MinAccumulator : keeps the min, has a min() method
- CountAccumulator : keeps count of number of values, has a nEntries() method
- SumAccumulator : keeps the sum of all values, has a sum() method
- SquareAccumulator : keeps the sum of all values squared, has a sum2() method
- TrueAccumulator : keeps a count of the number of true values, has a nTrueEntries() method
- FalseAccumulator : keeps a count of the number of false values, has a nFalseEntries() method
- BinomialAccumulator : set of TrueAccumulator and FalseAccumulator. Has extra nEntries(), efficiency() and efficiencyErr() methods
- AveragingAccumulator : set of CountAccumulator and SumAccumulator. Has an extra mean() method
- SigmaAccumulator : set of AveragingAccumulator and SquareAccumulator. Has extra methods variance(), standard_deviation() and meanErr()
- StatAccumulator : set of SigmaAccumulator, MinAccumulator and MaxAccumulator
some classes implement the most common Counters :
- PrintableCounter is the interface to be used for abstract counters that can be printed
- BufferableCounter is the base class for counters that can be buffered. It provides a buffer method returning a Buffer on the current counter
- Counter, AveragingCounter, SigmaCounter, StatCounter, BinomialCounter : standard counters based on the corresponding accumulators
- StatEntity : a counter meant to be backward compatible with the old one and actually being a set of StatAccumulator and BinomialAccumulator. StatEntity should not be used and should be dropped when ancient code has been ported to the other counters

Notes

All Accumulators and Counters defined above are provided in their atomic and non atomic versions

Here is an example of the typical usage of these classes :

AveragingCounter<> avg;
avg += 3;
avg += 5;
avg += 6;
std::cout << avg << std::endl;
SigmaCounter<> sig;
sig += 3;
sig += 5;
sig += 6;
std::cout << sig << std::endl;
AveragingCounter<float, atomicity::full> avg2;
{
  auto buf = avg2.buffer();
  for ( int i = 0; i < 1000; i++ ) buf += i;
  // single update of original counter when buf is destroyed
}
std::cout << avg2 << std::endl;
BinomialCounter<> bin;
bin += false;
bin += true;
bin += true;
bin += false;
bin += false;
std::cout << bin << std::endl;
StatEntity se;
se += 3;
se += 5;
se += 6;
std::cout << se << std::endl;

Typedef Documentation

template<typename Arithmetic , typename Result = double>

using Gaudi::Accumulators::fp_result_type = typedef std::conditional_t<std::is_integral<Arithmetic>::value, Result, Arithmetic>

type_trait for the result type of a floating point operation on the type Arithmetic

Definition at line 194 of file Counters.h.

template<typename T >

using Gaudi::Accumulators::has_fetch_add = typedef typename Gaudi::cpp17::is_detected<has_fetch_add_, T>::value_t

Definition at line 188 of file Counters.h.

template<typename T , typename = int>

using Gaudi::Accumulators::has_fetch_add_ = typedef decltype( std::atomic<T>{}.fetch_add( 0 ) )

type_traits for checking the presence of fetch_add in std::atomic<T>

Definition at line 186 of file Counters.h.

template<typename Arithmetic , atomicity Atomicity = atomicity::full>

using Gaudi::Accumulators::Maximum = typedef Extremum<Arithmetic, Atomicity, std::greater<Arithmetic>, std::numeric_limits<Arithmetic>::lowest>

An Maximum ValueHandler operator(a, b) means a = max(a, b) In case of full atomicity, compare_exchange_weak is used.

Definition at line 333 of file Counters.h.

template<typename Arithmetic , atomicity Atomicity = atomicity::full>

using Gaudi::Accumulators::Minimum = typedef Extremum<Arithmetic, Atomicity, std::less<Arithmetic>, std::numeric_limits<Arithmetic>::max>

A Minimun ValueHandler operator(a, b) means a = min(a, b) In case of full atomicity, compare_exchange_weak is used.

Definition at line 326 of file Counters.h.

template<typename Arithmetic , atomicity Atomicity = atomicity::full>

using Gaudi::Accumulators::StatAccumulator = typedef AccumulatorSet<Arithmetic, Atomicity, SigmaAccumulator, MinAccumulator, MaxAccumulator>

StatAccumulator.

A StatAccumulator is an Accumulator able to compute an average, variance/rms and min/max

See also: Gaudi::Accumulators for detailed documentation

Definition at line 589 of file Counters.h.

template<typename Arithmetic = double, atomicity Atomicity = atomicity::full>

using Gaudi::Accumulators::SummingCounter = typedef AveragingCounter<Arithmetic, Atomicity>

Definition at line 729 of file Counters.h.

Enumeration Type Documentation

enum Gaudi::Accumulators::atomicity

strong

Defines atomicity of the accumulators.

Enumerator
none
full

Definition at line 149 of file Counters.h.

149 { none, full };

Gaudi::Accumulators::atomicity::none

Gaudi::Accumulators::atomicity::full

Function Documentation

template<typename Counter , typename Container , typename Fun >

void Gaudi::Accumulators::accumulate	(	Counter &	counter,
		const Container &	container,
		Fun	f = `Identity{}`
	)

A helper function for accumulating data from a container into a counter This is internally using buffers so that the original counter is only updated once.

Definition at line 824 of file Counters.h.

                                                                                    {} ) {
       auto b = counter.buffer();
       for ( const auto& elem : container ) b += f( elem );
     }