This class gathers statistics about a given metric over time, like its average, standard deviation, and exponentially weighted moving average. More...

#include <RollingStat.h>

Public Types
typedef Core::Time::SteadyClock	Clock
	Clock used for exceptional values.
typedef Clock::time_point	TimePoint
	Time point used for exceptional values.
Public Member Functions
	RollingStat ()
	Constructor.
	~RollingStat ()
	Destructor.
double	getAverage () const
	Return mean, or 0 if no values reported.
uint64_t	getCount () const
	Return number of values reported.
double	getEWMA2 () const
	Return exponentially weighted moving average with alpha of 0.5, or 0 if no values reported.
double	getEWMA4 () const
	Return exponentially weighted moving average with alpha of 0.25, or 0 if no values reported.
uint64_t	getExceptionalCount () const
	Return total number of exceptional values reported.
uint64_t	getLast () const
	Return last value reported, or 0 if no values reported.
std::vector< std::pair < TimePoint, uint64_t > >	getLastExceptional () const
	Return up to the last 5 exceptional values reported, newest first.
uint64_t	getMin () const
	Return the smallest value reported, or 0 if no values reported.
uint64_t	getMax () const
	Return the largest value reported, or 0 if no values reported.
uint64_t	getSum () const
	Return the cumulative total of all values reported, or 0 if no values reported.
double	getStdDev () const
	Return the standard deviation of all values reported, or 0 if no values reported.
void	noteExceptional (TimePoint when, uint64_t value)
	Report an exceptional value.
void	push (uint64_t value)
	Report a value.
void	updateProtoBuf (Protocol::RollingStat &message) const
	Serialize all the stats into the given empty ProtoBuf message.
Private Attributes
uint64_t	count
double	ewma2
double	ewma4
uint64_t	exceptionalCount
uint64_t	last
std::deque< std::pair < TimePoint, uint64_t > >	lastExceptional
uint64_t	max
uint64_t	min
uint64_t	sum
uint64_t	sumSquares
	Used to calculate standard deviation.
Friends
std::ostream &	operator<< (std::ostream &os, const RollingStat &stat)
	Print all the stats.

Detailed Description

This class gathers statistics about a given metric over time, like its average, standard deviation, and exponentially weighted moving average.

This class also keeps track of the last 5 "exceptional" values, typically those that are above some pre-defined threshold.

This currently assumes your metric is a uint64_t. It could probably be abstracted out in some way, but most metrics in LogCabin seem to fit this category.

Definition at line 44 of file RollingStat.h.

Member Typedef Documentation

typedef Core::Time::SteadyClock LogCabin::Core::RollingStat::Clock

Clock used for exceptional values.

Definition at line 49 of file RollingStat.h.

typedef Clock::time_point LogCabin::Core::RollingStat::TimePoint

Time point used for exceptional values.

Definition at line 53 of file RollingStat.h.

Constructor & Destructor Documentation

LogCabin::Core::RollingStat::RollingStat ( )

Constructor.

Definition at line 25 of file RollingStat.cc.

LogCabin::Core::RollingStat::~RollingStat ( )

Destructor.

Definition at line 39 of file RollingStat.cc.

Member Function Documentation

double LogCabin::Core::RollingStat::getAverage ( ) const

Return mean, or 0 if no values reported.

Definition at line 44 of file RollingStat.cc.

uint64_t LogCabin::Core::RollingStat::getCount ( ) const

Return number of values reported.

Definition at line 52 of file RollingStat.cc.

double LogCabin::Core::RollingStat::getEWMA2 ( ) const

Return exponentially weighted moving average with alpha of 0.5, or 0 if no values reported.

Definition at line 58 of file RollingStat.cc.

double LogCabin::Core::RollingStat::getEWMA4 ( ) const

Return exponentially weighted moving average with alpha of 0.25, or 0 if no values reported.

Definition at line 64 of file RollingStat.cc.

uint64_t LogCabin::Core::RollingStat::getExceptionalCount ( ) const

Return total number of exceptional values reported.

Definition at line 70 of file RollingStat.cc.

uint64_t LogCabin::Core::RollingStat::getLast ( ) const

Return last value reported, or 0 if no values reported.

Definition at line 84 of file RollingStat.cc.

std::vector< std::pair< RollingStat::TimePoint, uint64_t > > LogCabin::Core::RollingStat::getLastExceptional ( ) const

Return up to the last 5 exceptional values reported, newest first.

Definition at line 76 of file RollingStat.cc.

uint64_t LogCabin::Core::RollingStat::getMin ( ) const

Return the smallest value reported, or 0 if no values reported.

Definition at line 90 of file RollingStat.cc.

uint64_t LogCabin::Core::RollingStat::getMax ( ) const

Return the largest value reported, or 0 if no values reported.

Definition at line 96 of file RollingStat.cc.

uint64_t LogCabin::Core::RollingStat::getSum ( ) const

Return the cumulative total of all values reported, or 0 if no values reported.

Definition at line 102 of file RollingStat.cc.

double LogCabin::Core::RollingStat::getStdDev ( ) const

Return the standard deviation of all values reported, or 0 if no values reported.

Definition at line 108 of file RollingStat.cc.

void LogCabin::Core::RollingStat::noteExceptional	(	TimePoint	when,
		uint64_t	value
	)

Report an exceptional value.

Note that this does not include a 'push'; you may want to do that separately.

Parameters:

when	The time the exceptional situation occurred (by convention, this is usually its start time).
value	The exceptional value.

Definition at line 117 of file RollingStat.cc.

void LogCabin::Core::RollingStat::push ( uint64_t value )

Report a value.

Definition at line 126 of file RollingStat.cc.

void LogCabin::Core::RollingStat::updateProtoBuf ( Protocol::RollingStat & message ) const

Serialize all the stats into the given empty ProtoBuf message.

Definition at line 154 of file RollingStat.cc.

Friends And Related Function Documentation

std::ostream& operator<<	(	std::ostream &	os,
		const RollingStat &	stat
	)		`[friend]`

Print all the stats.

Definition at line 180 of file RollingStat.cc.

Member Data Documentation

uint64_t LogCabin::Core::RollingStat::count [private]

Definition at line 143 of file RollingStat.h.

double LogCabin::Core::RollingStat::ewma2 [private]

Definition at line 144 of file RollingStat.h.

double LogCabin::Core::RollingStat::ewma4 [private]

Definition at line 145 of file RollingStat.h.

uint64_t LogCabin::Core::RollingStat::exceptionalCount [private]

Definition at line 146 of file RollingStat.h.

uint64_t LogCabin::Core::RollingStat::last [private]

Definition at line 147 of file RollingStat.h.

std::deque<std::pair<TimePoint, uint64_t> > LogCabin::Core::RollingStat::lastExceptional [private]

Definition at line 148 of file RollingStat.h.

uint64_t LogCabin::Core::RollingStat::max [private]

Definition at line 149 of file RollingStat.h.

uint64_t LogCabin::Core::RollingStat::min [private]

Definition at line 150 of file RollingStat.h.

uint64_t LogCabin::Core::RollingStat::sum [private]

Definition at line 151 of file RollingStat.h.

uint64_t LogCabin::Core::RollingStat::sumSquares [private]

Used to calculate standard deviation.

sum of x times x over all values.

Definition at line 155 of file RollingStat.h.

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

Core/RollingStat.h
Core/RollingStat.cc

Public Types

Public Member Functions