bdlm_metricdescriptor

Detailed Description

Provide an attribute class to describe a metric.

Outline

• Purpose
• Classes
• Description
  • Attributes
  • Usage

Purpose

Provide an attribute class to describe a metric.

Classes

• bdlm::MetricDescriptor: descriptive information for a metric

Description

This component provides a single unconstrained attribute class, bdlm::MetricDescriptor, that is used to supply descriptive information for a metric. A descriptor is supplied to a MetricsRegistry to identify a metric, which in-turn supplies that description to a higher-level metric publication system (like BALM or GUTS) via a concrete implementation of the bdlm::MetricsAdapter protocol.

Attributes

Name                   Type         Default
------------------     -----------  -------
metricNamespace        bsl::string  [1]
metricName             bsl::string  ""
instanceNumber         Uint64       0
objectTypeName         bsl::string  ""
objectTypeAbbreviation bsl::string  ""
objectIdentifier       bsl::string  [2]

[1] k_USE_METRICS_ADAPTER_NAMESPACE_SELECTION [2] k_USE_METRICS_ADAPTER_OBJECT_ID_SELECTION

: o 'metricNamespace' - a grouping value for published metrics, which is
:   expected to be have implementation specific details from the metric
:   publishing system.  Recommended practice is to use
:   'k_USE_METRICS_ADAPTER_NAMESPACE_SELECTION' indicating concrete
:   implementations of 'MetricsAdapter' should determine an appropriate
:   value for the metrics framework it adapts (this is often a configured
:   value for an application, e.g., a service name).
:
: o 'metricName' - the name of the metric (e.g., "requestCount")
:
: o 'instanceCount' - an instance number expected to ensure that a unique
:   'MetricsDescriptor' is created for each instance of an object reporting
:   metrics.  Recommended practice is to use 'bdlm::InstanceCount' to
:   generate this value.
:
: o 'objectTypeName' - a name that uniquely identifies the type generating
:   the metric (e.g., "bdlmt.fixedthreadpool").
:
: o 'objectTypeAbbreviation' - a shortened, but still unique, version of the
:   object type name (e.g., "ftp").
:
: o 'objectIdentifier' - an application unique value for identifying a
:   metric.  Recommended practice is to use
:   'k_USE_METRICS_ADAPTER_OBJECT_ID_SELECTION' indicating concrete
:   implementations of 'MetricsAdapter' should determine an appropriate value
:   for the metrics framework it adapts (this is often a value computed from
:   the other descriptor properties).

For example, for GUTS (an internal Bloomberg metric framework) using a guta::BdlmMetricsAdapter configured with the namespace "bdlm" and object identifier prefix "svc", supplying (metricNamespace: k_USE_METRICS_ADAPTER_NAMESPACE_SELECTION, metricName: "backlog", instanceNumber: InstanceCount::value<FixedThreadPool>(), objectTypeName: "bdlmt.fixedthreadpool", objectTypeAbbreviation: "ftp", objectIdentifier: _USE_METRICS_ADAPTER_OBJECT_ID_SELECTION) would result in a metric that is within the namespace "bdlm", had the metric name "backlog.g", and the tags {"identifier":"svc.ftp.1","type":"bdlmt.fixedthreadpool"}, assuming this was the first invocation of InstanceCount::value<FixedThreadPool>(). Note that the ".g" in "backlock.g" indicates a guage metric type.

Usage

The intended use of this component is illustrated in {bdlm_metricsadapter |Usage}.