[#BloombergLP-balm-MetricSample]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/balm.adoc[balm]::MetricSample
:relfileprefix: ../../
:mrdocs:

This class provides an _in‐core_ value‐semantic representation of a sample of metric values.

== Synopsis

Declared in `<balm_metricsample.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class MetricSample;
----

== Description

The class contains a collection of addresses to (external) `MetricRecord` objects holding the values for their respective metrics (aggregated over some period of time). The metric records contained by a sample are broken into a series of groups, which are represented by `MetricSampleGroup` objects. Each group contains a sequence of records and an elapsed time value, indicating the period of time over which those records were taken. This class also provides a timestamp value, used to indicate when the sample was collected. The class provides a method, `appendGroups`, that appends a group of metric records to the sample. Arrays supplied using `appendGroups` must be valid for the productive lifetime of the `MetricSample` object or until they are removed by calling `removeAllRecords`.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balm/MetricSample/const_iterator.adoc[`const_iterator`] 
| A `const_iterator` is an alias for an iterator over the non‐modifiable sample groups contained in a `MetricSample`.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balm/MetricSample/2constructor-0f.adoc[`MetricSample`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/balm/MetricSample/2destructor.adoc[`~MetricSample`] [.small]#[destructor]#
| Destroy this metric sample.
| xref:BloombergLP/balm/MetricSample/operator_assign.adoc[`operator=`] 
| Assign to this sample the value of the specified `rhs` sample.
| xref:BloombergLP/balm/MetricSample/appendGroup-0c.adoc[`appendGroup`] 
| `appendGroup` overloads
| xref:BloombergLP/balm/MetricSample/begin.adoc[`begin`] 
| Return an iterator positioned at the beginning of the sequence of `MetricSampleGroup` objects contained by this object.
| xref:BloombergLP/balm/MetricSample/end.adoc[`end`] 
| Return an iterator positioned one past the final `MetricSampleGroup` object in the sequence of sample groups contained by this object.
| xref:BloombergLP/balm/MetricSample/numGroups.adoc[`numGroups`] 
| Return the number of record groups (i.e., `MetricSampleGroup` objects) that are contained in this object.
| xref:BloombergLP/balm/MetricSample/numRecords.adoc[`numRecords`] 
| Return the total number of records in this sample (i.e., the sum of the lengths of all the appended record groups).
| xref:BloombergLP/balm/MetricSample/print.adoc[`print`] 
| Format this object to the specified output stream.
| xref:BloombergLP/balm/MetricSample/removeAllRecords.adoc[`removeAllRecords`] 
| Remove all metric records from this sample.
| xref:BloombergLP/balm/MetricSample/sampleGroup.adoc[`sampleGroup`] 
| Return a reference to the non‐modifiable `MetricSampleGroup` object at the specified `index` in this sample.
| xref:BloombergLP/balm/MetricSample/setTimeStamp.adoc[`setTimeStamp`] 
| Set the timestamp (used to indicate when the sample was taken) to the specified `timeStamp`.
| xref:BloombergLP/balm/MetricSample/timeStamp.adoc[`timeStamp`] 
| Return a reference to the non‐modifiable timestamp for this sample.
| xref:BloombergLP/balm/MetricSample/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<MetricSample, UsesBslmaAllocator>`] 
| Declare that this type uses a `bslma` allocator.
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/balm/operator_eq-0d.adoc[BloombergLP::balm::operator==]`
| Return `true` if the specified `lhs` and `rhs` samples have the same value, and `false` otherwise.
|===

== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balm/operator_not_eq-0d.adoc[`operator!=`]
| Return `true` if the specified `lhs` and `rhs` samples do not have the same value, and `false` otherwise.
|===


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