Summary class Null safety

Similar to a Histogram, a Summary samples observations (usually things like request durations and response sizes). While it also provides a total count of observations and a sum of all observed values, it calculates configurable quantiles over a sliding time window.

Inheritance

Constructors

Summary({required String name, required String help, List<String> labelNames = const [], List<Quantile> quantiles = const [], Duration maxAge = const Duration(minutes: 10), int ageBuckets = 5, Collect<Summary>? collectCallback})
Construct a new Summary with a name, help text, optional labelNames, optional quantiles, optional maxAge and optional ageBuckets. If labelNames are provided, use labels(...) to assign label values. If no quantiles are provided the summary only has a count and sum. If not provided, maxAge defaults to 10 minutes and ageBuckets to 5. The optional collectCallback is called at the beginning of collect and allows to update the value of the summary before collecting it.

Properties

ageBuckets int
Set the number of buckets used to implement the sliding time window. If your time window is 10 minutes, and you have ageBuckets=5, buckets will be switched every 2 minutes. The value is a trade-off between resources (memory and cpu for maintaining the bucket) and how smooth the time window is moved.
final
collectCallback Collect<Summary>?
Optional callback called in collect before samples are collected.
final
count double
Access the count of elements in a summary without labels.
read-only
hashCode int
The hash code for this object.
read-onlyinherited
help String
The help text of the metric.
finalinherited
labelNames List<String>
The unmodifiable list of labelNames assigned to this metric.
finalinherited
maxAge Duration
Set the duration of the time window is, i.e. how long observations are kept before they are discarded.
final
name String
The name of the metric.
finalinherited
quantiles List<Quantile>
Quantiles to observe by the summary.
final
runtimeType Type
A representation of the runtime type of the object.
read-onlyinherited
sum double
Access the total sum of the elements in a summary without labels.
read-only
values Map
Access the value of each quantile of a summary without labels.
read-only

Methods

clear() → void
Remove all Child metrics.
inherited
collect() Future<Iterable<MetricFamilySamples>>
collect all metrics and samples that are part of this Collector.
override
collectNames() Iterable<String>
Collect all metric names, including child metrics.
override
labels(List<String> labelValues) SummaryChild
Create a Child metric and assign the labelValues. The size of the labelValues has to match the labelNames of the metric.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
inherited
observe(double v) → void
Observe a new value v and store it in the summary without labels.
observeDuration<T>(Future<T> f) Future<T>
Observe the duration of the Future f and store it in the summary without labels.
observeDurationSync<T>(T callback()) → T
Observe the duration of callback and store it in the summary without labels.
register([CollectorRegistry? registry]) → void
Register the Collector at a registry. If no registry is provided, the CollectorRegistry.defaultRegistry is used.
inherited
remove(List<String> labelValues) → void
Remove a Child metric based on it's label values.
inherited
toString() String
A string representation of this object.
inherited

Operators

operator ==(Object other) bool
The equality operator.
inherited

Constants

quantileLabel → const String
'quantile'