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Author image Paul Evans


Net::Prometheus::Histogram - count the distribution of numeric observations


   use Net::Prometheus;
   use Time::HiRes qw( time );

   my $client = Net::Prometheus->new;

   my $histogram = $client->new_histogram(
      name => "request_seconds",
      help => "Summary request processing time",

   sub handle_request
      my $start = time();


      $summary->observe( time() - $start );


This class provides a histogram metric - a count of the distribution of individual numerical observations into distinct buckets. These are usually reports of times. It is a subclass of Net::Prometheus::Metric.


Instances of this class are not usually constructed directly, but instead via the Net::Prometheus object that will serve it:

   $histogram = $prometheus->new_histogram( %args )

This takes the same constructor arguments as documented in Net::Prometheus::Metric, and additionally the following:

buckets => ARRAY

A reference to an ARRAY containing numerical upper bounds for the buckets.

bucket_min => NUM
bucket_max => NUM
buckets_per_decade => ARRAY[ NUM ]

Since version 0.10.

A more flexible alternative to specifying literal bucket sizes. The values given in buckets_per_decade are repeated, multiplied by various powers of 10 to generate values between bucket_min (or a default of 0.001 if not supplied) and bucket_max (or a default of 1000 if not supplied).


   @bounds = $histogram->bucket_bounds

Returns the bounding values for each of the buckets, excluding the final +Inf bucket.


   $histogram->observe( @label_values, $value )
   $histogram->observe( \%labels, $value )

   $child->observe( $value )

Increment the histogram sum by the given value, and each bucket count by 1 where the value is less than or equal to the bucket upper bound.


Paul Evans <leonerd@leonerd.org.uk>