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Metrics::Any::AdapterBUser:Contributed PerMetrics::Any::AdapterBase::Stored(3)

NAME
       "Metrics::Any::AdapterBase::Stored" - a base class for metrics adapters
       which store values

DESCRIPTION
       This base class assists in creating Metrics::Any::Adapter classes which
       store values of reported	metrics	directly. These	can then be retrieved
       later by	the containing application, or the subclass code, by using the
       "walk" method.

       This base class internally stores counter and gauge metrics as single
       scalar values directly. In order	to provide flexibility for a variety
       of use-cases, it	requires assistance from the implementing class	on how
       to store	distribution and timer metrics.	The implementing class should
       provide these methods, returning	whatever values	it wishes to implement
       them with. These	values are stored by the base class, and handed	back
       as part of the "walk" method.

       The base	class stores a value for each unique set of labels and values
       on every	metric;	the subclass does not need to handle this.

METHODS
   walk
	  $stored->walk( $code )

	     $code->( $type, $name, $labels, $value )

       Given a CODE reference, this method invokes it once per labelset	of
       every stored metric.

       For each	labelset, $type	will give the metric type (as a	string,	either
       "counter", "distribution", "gauge" or "timer"), $name gives the name it
       was registered with, $labels will be a reference	to an even-sized array
       containing label	names and values.

       For counter and gauge metrics, $value will be a numerical scalar	giving
       the current value. For distribution and timer metrics, $value will be
       whatever	the implementing class's corresponding "store_distribution" or
       "store_timer" method returns for	them.

   clear_values
	  $stored->clear_values

       Clears all of the metric	storage. Every labelset	of every metric	is
       deleted.	 The metric definitions	themselves remain.

REQUIRED METHODS
   store_distribution
   store_timer
	  $storage = $stored->store_distribution( $storage, $amount )

	  $storage = $stored->store_timer( $storage, $duration )

       The implementing	class must provide these two methods to	assist in the
       management of storage for distribution and timer	metrics.

       When a new observation for the metric is	required, the method will be
       invoked,	passing	in the currently-stored	perl value for the given
       metric and label	values,	and the	new observation. Whatever the method
       returns is stored by the	base class, to be passed in next time or used
       by the "walk" method.

       The base	class stores this value	directly and does not otherwise
       interact	with it; letting the implementing class	decide what is best.
       For example, a simple implementation may	just store every observation
       individually by pushing them into an array; so the $storage would be an
       ARRAY reference:

	  sub store_distribution
	  {
	     my	$self =	shift;
	     my	( $storage, $amount ) =	@_;

	     push @$storage, $amount;

	     return $storage;
	  }

AUTHOR
       Paul Evans <leonerd@leonerd.org.uk>

perl v5.32.1			  2021-02-Metrics::Any::AdapterBase::Stored(3)

NAME | DESCRIPTION | METHODS | REQUIRED METHODS | AUTHOR

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