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

This class defines a thread‐aware mechanism for registering metrics and metric categories.

== Synopsis

Declared in `<balm_metricregistry.h>`

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

== Description

A metric is uniquely identified by its name and category, and the metric registry provides a mapping from those identifying properties to a `balm::MetricId`. A `balm::MetricRegistry` object also provides a mapping from a category name to the address of a non‐modifiable `balm::Category` object.

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balm/MetricRegistry/2constructor.adoc[`MetricRegistry`]         [.small]#[constructor]#
| Create an empty metric registry.
| xref:BloombergLP/balm/MetricRegistry/2destructor.adoc[`~MetricRegistry`] [.small]#[destructor]#
| Destroy this metric registry.
| xref:BloombergLP/balm/MetricRegistry/addCategory.adoc[`addCategory`] 
| Add `category` to this registry unless it is already registered.
| xref:BloombergLP/balm/MetricRegistry/addId.adoc[`addId`] 
| Add a metric id for `category` and `name` if not already registered.
| xref:BloombergLP/balm/MetricRegistry/createUserDataKey.adoc[`createUserDataKey`] 
| Return a new unique key for associating user data with metrics.
| xref:BloombergLP/balm/MetricRegistry/findCategory.adoc[`findCategory`] 
| Find the registered category named `category`.
| xref:BloombergLP/balm/MetricRegistry/findId.adoc[`findId`] 
| Find the metric id for `category` and `name` in this registry.
| xref:BloombergLP/balm/MetricRegistry/getAllCategories.adoc[`getAllCategories`] 
| Append to the specified `categories` the addresses of all the categories registered by this `balm::MetricRegistry` object.
| xref:BloombergLP/balm/MetricRegistry/getCategory.adoc[`getCategory`] 
| Return the category for `category`, registering it if needed.
| xref:BloombergLP/balm/MetricRegistry/getId.adoc[`getId`] 
| Return a metric id for `category` and `name`, registering if needed.
| xref:BloombergLP/balm/MetricRegistry/numCategories.adoc[`numCategories`] 
| Return the number of categories in this registry.
| xref:BloombergLP/balm/MetricRegistry/numMetrics.adoc[`numMetrics`] 
| Return the number of metrics in this registry.
| xref:BloombergLP/balm/MetricRegistry/print.adoc[`print`] 
| Format this object to the specified output `stream`.
| xref:BloombergLP/balm/MetricRegistry/registerCategoryHolder.adoc[`registerCategoryHolder`] 
| Register `holder` with `category` in this registry.
| xref:BloombergLP/balm/MetricRegistry/setAllCategoriesEnabled.adoc[`setAllCategoriesEnabled`] 
| Set the enabled state of all categories to `value`.
| xref:BloombergLP/balm/MetricRegistry/setCategoryEnabled.adoc[`setCategoryEnabled`] 
| Set whether `category` is enabled to `value`.
| xref:BloombergLP/balm/MetricRegistry/setFormat.adoc[`setFormat`] 
| Set the format for `metricId` to `format`.
| xref:BloombergLP/balm/MetricRegistry/setPreferredPublicationType.adoc[`setPreferredPublicationType`] 
| Set the preferred publication type of `metric` to `type`.
| xref:BloombergLP/balm/MetricRegistry/setUserData-0b.adoc[`setUserData`] 
| `setUserData` overloads
| xref:BloombergLP/balm/MetricRegistry/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<MetricRegistry, UsesBslmaAllocator>`] 
| Declare that this type uses a `bslma` allocator.
|===



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