prom::NullAdapter Class Reference

A backend that records nothing. More...

#include <null_adapter.hpp>

Inheritance diagram for prom::NullAdapter:

Collaboration diagram for prom::NullAdapter:

Public Member Functions
	NullAdapter ()
std::string_view	backend_name () const noexcept override
	Stable identifier of the backend (e.g. "null", "prometheus-cpp").
MetricHandle	register_metric (const MetricMeta &meta) noexcept override
	Register a metric family.
MetricHandle	resolve (const MetricHandle &, const Labels &dynamic) noexcept override
	Resolve the labeled child of family for the given dynamic labels, creating it on first request.
void	inc (const MetricHandle &, const double amount) noexcept override
	Increase the series behind handle by amount (counter/gauge).
void	dec (const MetricHandle &, const double amount) noexcept override
	Decrease the series behind handle by amount (gauge).
void	set (const MetricHandle &, const double value) noexcept override
	Set the series behind handle to value (gauge/untyped).
void	observe (const MetricHandle &, const double value) noexcept override
	Record an observation against handle (histogram/summary).
void	set_info (const MetricHandle &, const std::span< const Label > labels) noexcept override
	Replace the label set carried by an info metric.
void	set_state (const MetricHandle &, std::string_view state, bool active) noexcept override
	Set the boolean value of one member of a state set.
void	set_unit (const MetricHandle &, const Unit &unit) noexcept override
	Late unit inference hook.
Public Member Functions inherited from prom::Adapter
	Adapter ()=default
	Adapter (const Adapter &)=delete
Adapter &	operator= (const Adapter &)=delete
	Adapter (Adapter &&)=delete
Adapter &	operator= (Adapter &&)=delete
virtual	~Adapter ()=default

Detailed Description

A backend that records nothing.

Registration and resolution log at debug and hand back a single shared inert MetricState; mutations log at trace. Logging is null-guarded so construction before any logger setup is safe.

Constructor & Destructor Documentation

NullAdapter()

prom::NullAdapter::NullAdapter ( )

inline

Member Function Documentation

backend_name()

std::string_view prom::NullAdapter::backend_name ( ) const

inlineoverridevirtualnoexcept

Stable identifier of the backend (e.g. "null", "prometheus-cpp").

Implements prom::Adapter.

dec()

void prom::NullAdapter::dec ( const MetricHandle &  handle, const double  amount  )

inlineoverridevirtualnoexcept

Decrease the series behind handle by amount (gauge).

Implements prom::Adapter.

inc()

void prom::NullAdapter::inc ( const MetricHandle &  handle, const double  amount  )

inlineoverridevirtualnoexcept

Increase the series behind handle by amount (counter/gauge).

Implements prom::Adapter.

observe()

void prom::NullAdapter::observe ( const MetricHandle &  handle, const double  value  )

inlineoverridevirtualnoexcept

Record an observation against handle (histogram/summary).

Implements prom::Adapter.

register_metric()

MetricHandle prom::NullAdapter::register_metric ( const MetricMeta &  meta )

inlineoverridevirtualnoexcept

Register a metric family.

Must return a non-null handle even on failure (fall back to an inert handle) so callers never have to null-check.

Implements prom::Adapter.

resolve()

MetricHandle prom::NullAdapter::resolve ( const MetricHandle &  family, const Labels &  dynamic  )

inlineoverridevirtualnoexcept

Resolve the labeled child of family for the given dynamic labels, creating it on first request.

The backend owns the child cache. Must return a non-null handle.

Implements prom::Adapter.

set()

void prom::NullAdapter::set ( const MetricHandle &  handle, const double  value  )

inlineoverridevirtualnoexcept

Set the series behind handle to value (gauge/untyped).

Implements prom::Adapter.

set_info()

void prom::NullAdapter::set_info ( const MetricHandle &  handle, const std::span< const Label >  labels  )

inlineoverridevirtualnoexcept

Replace the label set carried by an info metric.

Implements prom::Adapter.

set_state()

void prom::NullAdapter::set_state ( const MetricHandle &  handle, std::string_view  state, bool  active  )

inlineoverridevirtualnoexcept

Set the boolean value of one member of a state set.

Implements prom::Adapter.

set_unit()

void prom::NullAdapter::set_unit ( const MetricHandle &  , const Unit &    )

inlineoverridevirtualnoexcept

Late unit inference hook.

Called when a metric that declared no unit latches the unit of its first dimensional observation. Optional — backends that cannot rename a registered series may ignore it.

Reimplemented from prom::Adapter.

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

• include/prom/null_adapter.hpp