NewMultiRegistry creates a new standardRegistry that wraps multiple Registries.

NewVoidRegistry is a noop implementation of metrics.Registry.

RegisterDatadog registers the metrics pusher if this didn't happen yet and creates a datadog Registry instance.

RegisterPrometheus registers all Prometheus metrics.

RegisterStatsd registers the metrics pusher if this didn't happen yet and creates a statsd Registry instance.

StopDatadog stops internal datadogTicker which controls the pushing of metrics to DD Agent and resets it to `nil`.

StopStatsd stops internal statsdTicker which controls the pushing of metrics to StatsD Agent and resets it to `nil`.

Registry has to implemented by any system that wants to monitor and expose metrics.